# Fusion power

(Redirected from Fusion reactor)

Fusion power is a proposed form of power generation that would generate electricity by using heat from nuclear fusion reactions. In a fusion process, two lighter atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices designed to harness this energy are known as fusion reactors.

The Joint European Torus (JET) magnetic fusion experiment in 1991

Fusion processes require fuel and a confined environment with sufficient temperature, pressure, and confinement time to create a plasma in which fusion can occur. The combination of these figures that results in a power-producing system is known as the Lawson criterion. In stars, the most common fuel is hydrogen, and gravity provides extremely long confinement times that reach the conditions needed for fusion energy production. Proposed fusion reactors generally use heavy hydrogen isotopes such as deuterium and tritium (and especially a mixture of the two), which react more easily than protium (the most common hydrogen isotope), to allow them to reach the Lawson criterion requirements with less extreme conditions. Most designs aim to heat their fuel to around 100 million degrees, which presents a major challenge in producing a successful design.

As a source of power, nuclear fusion is expected to have many advantages over fission. These include reduced radioactivity in operation and little high-level nuclear waste, ample fuel supplies, and increased safety. However, the necessary combination of temperature, pressure, and duration has proven to be difficult to produce in a practical and economical manner. Research into fusion reactors began in the 1940s, but to date, no design has produced more fusion power output than the electrical power input.[1] A second issue that affects common reactions is managing neutrons that are released during the reaction, which over time degrade many common materials used within the reaction chamber.

Fusion researchers have investigated various confinement concepts. The early emphasis was on three main systems: z-pinch, stellarator, and magnetic mirror. The current leading designs are the tokamak and inertial confinement (ICF) by laser. Both designs are under research at very large scales, most notably the ITER tokamak in France, and the National Ignition Facility (NIF) laser in the United States. Researchers are also studying other designs that may offer cheaper approaches. Among these alternatives, there is increasing interest in magnetized target fusion and inertial electrostatic confinement, and new variations of the stellarator.

## Background

The Sun, like other stars, is a natural fusion reactor, where stellar nucleosynthesis transforms lighter elements into heavier elements with the release of energy.

Binding energy for different atomic nuclei. Iron-56 has the highest, making it the most stable. Nuclei to the left are likely to release energy when they fuse (fusion); those to the far right are likely to be unstable and release energy when they split (fission).

### Mechanism

Fusion reactions occur when two or more atomic nuclei come close enough for long enough that the nuclear force pulling them together exceeds the electrostatic force pushing them apart, fusing them into heavier nuclei. For nuclei heavier than iron-56, the reaction is endothermic, requiring an input of energy.[2] The heavy nuclei bigger than iron have many more protons resulting in a greater repulsive force. For nuclei lighter than iron-56, the reaction is exothermic, releasing energy when they fuse. Since hydrogen has a single proton in its nucleus, it requires the least effort to attain fusion, and yields the most net energy output. Also since it has one electron, hydrogen is the easiest fuel to fully ionize.

The strong force acts only over short distances (at most one femtometre, the diameter of one proton or neutron), while the repulsive electrostatic force between nuclei acts over longer distances. In order to undergo fusion, the fuel atoms need to be given enough kinetic energy to approach each other closely enough for the strong force to overcome the electrostatic repulsion. The amount of kinetic energy needed to bring the fuel atoms close enough is known as the "Coulomb barrier". Ways of providing this energy include speeding up atoms in a particle accelerator, or heating them to high temperatures.

Once an atom is heated above its ionization energy, its electrons are stripped away, leaving just the bare nucleus. This process is known as ionization, and the resulting nucleus is known as an ion. The result is a hot cloud of ions and free electrons formerly attached to them known as plasma. Because the charges are separated, plasmas are electrically conductive and magnetically controllable. Many fusion devices take advantage of this to confine the particles as they are heated.

### Cross section

The fusion reaction rate increases rapidly with temperature until it maximizes and then gradually drops off. The deuterium-tritium fusion rate peaks at a lower temperature (about 70 keV, or 800 million kelvin) and at a higher value than other reactions commonly considered for fusion energy.

A reaction's cross section, denoted σ, measures the probability that a fusion reaction will happen. This depends on the relative velocity of the two nuclei. Higher relative velocities generally increase the probability, but the probability begins to decrease again at very high energies.[3]

In a plasma, particle velocity can be characterized using a probability distribution. If the plasma is thermalized, the distribution looks like a Gaussian curve, or Maxwell–Boltzmann distribution. In this case, it is useful to use the average particle cross section over the velocity distribution. This is entered into the volumetric fusion rate:[4]

${\displaystyle P_{\text{fusion}}=n_{A}n_{B}\langle \sigma v_{A,B}\rangle E_{\text{fusion}}}$

where:

• ${\displaystyle P_{\text{fusion}}}$  is the energy made by fusion, per time and volume
• n is the number density of species A or B, of the particles in the volume
• ${\displaystyle \langle \sigma v_{A,B}\rangle }$  is the cross section of that reaction, average over all the velocities of the two species v
• ${\displaystyle E_{\text{fusion}}}$  is the energy released by that fusion reaction.

### Lawson criterion

The Lawson criterion shows how energy output varies with temperature, density, speed of collision for any given fuel. This equation was central to John Lawson's analysis of fusion working with a hot plasma. Lawson assumed an energy balance, shown below.[4]

${\displaystyle P_{\text{out}}=\eta _{\text{capture}}\left(P_{\text{fusion}}-P_{\text{conduction}}-P_{\text{radiation}}\right)}$

where:

• ${\displaystyle P_{\text{out}}}$  is the net power from fusion
• ${\displaystyle \eta _{\text{capture}}}$  is the efficiency of capturing the output of the fusion
• ${\displaystyle P_{\text{fusion}}}$  is the rate of energy generated by the fusion reactions
• ${\displaystyle P_{\text{conduction}}}$  is the conduction losses as energetic mass leaves the plasma
• ${\displaystyle P_{\text{radiation}}}$  is the radiation losses as energy leaves as light.

Plasma clouds lose energy through conduction and radiation.[4] Conduction occurs when ions, electrons, or neutrals impact other substances, typically a surface of the device, and transfer a portion of their kinetic energy to the other atoms. Radiation is energy that leaves the cloud as light. Radiation increases with temperature. Fusion power technologies must overcome these losses.

### Triple product: density, temperature, time

The Lawson criterion argues that a machine holding a thermalized and quasi-neutral plasma has to generate enough energy to overcome its energy losses. The amount of energy released in a given volume is a function of the temperature, and thus the reaction rate on a per-particle basis, the density of particles within that volume, and finally the confinement time, the length of time that energy stays within the volume.[4][5] This is known as the "triple product": the plasma density, temperature, and confinement time.[6]

In magnetic confinement, the density is low, on the order of a "good vacuum". For instance, in the ITER device the fuel density is about 10 x 1019, which is about one-millionth atmospheric density.[7] This means that the temperature and/or confinement time must increase. Fusion-relevant temperatures have been achieved using a variety of heating methods that were developed in the early 1970s. In modern machines, as of 2019, the major remaining issue was the confinement time. Plasmas in strong magnetic fields are subject to a number of inherent instabilities, which must be suppressed to reach useful durations. One way to do this is to simply make the reactor volume larger, which reduces the rate of leakage due to classical diffusion. This is why ITER is so large.

In contrast, inertial confinement systems approach useful triple product values via higher density, and have short confinement intervals. In NIF, the initial frozen hydrogen fuel load has a density less than water that is increased to about 100 times the density of lead. In these conditions, the rate of fusion is so high that the fuel fuses in the microseconds it takes for the heat generated by the reactions to blow the fuel apart. Although NIF is also large, this is a function of its "driver" design, not inherent to the fusion process.

### Energy capture

Multiple approaches have been proposed to capture the energy that fusion produces. The simplest is to heat a fluid. The commonly targeted D-T reaction releases much of its energy as fast-moving neutrons. Electrically neutral, the neutron is unaffected by the confinement scheme. In most designs, it is captured in a thick "blanket" of lithium surrounding the reactor core. When struck by a high-energy neutron, the blanket heats up. It is then actively cooled with a working fluid that drives a turbine to produce power.

Another design proposed to use the neutrons to breed fission fuel in a blanket of nuclear waste, a concept known as a fission-fusion hybrid. In these systems, the power output is enhanced by the fission events, and power is extracted using systems like those in conventional fission reactors.[8]

Designs that use other fuels, notably the proton-boron aneutronic fusion reaction, release much more of their energy in the form of charged particles. In these cases, power extraction systems based on the movement of these charges are possible. Direct energy conversion was developed at Lawrence Livermore National Laboratory (LLNL) in the 1980s as a method to maintain a voltage directly using fusion reaction products. This has demonstrated energy capture efficiency of 48 percent.[9]

## Methods

### Plasma behavior

Plasma is an ionized gas that conducts electricity.[10] In bulk, it is modeled using magnetohydrodynamics, which is a combination of the Navier–Stokes equations governing fluids and Maxwell's equations governing how magnetic and electric fields behave.[11] Fusion exploits several plasma properties, including:

• Self-organizing plasma conducts electric and magnetic fields. Its motions generate fields that can in turn contain it.[12]
• Diamagnetic plasma can generate its own internal magnetic field. This can reject an externally applied magnetic field, making it diamagnetic.[13]
• Magnetic mirrors can reflect plasma when it moves from a low to high density field.[14]:24

#### Neural networks

A deep reinforcement learning system has been used to control a tokomak-based reactor. The AI was able to manipulate the magnetic coils to manage the plasma. The system was able to continuously adjust the system to maintain appropriate behavior (more complex than step-based systems). In 2014, Google began working with California-based fusion company TAE Technologies to control the Joint European Torus (JET) to predict plasma behavior.[15] DeepMind has also developed a control scheme with JET.

### Magnetic confinement

• Tokamak: the most well-developed and well-funded approach. This method drives hot plasma around in a magnetically confined torus, with an internal current. When completed, ITER will become the world's largest tokamak. As of September 2018 an estimated 226 experimental tokamaks were either planned, decommissioned or operating (50) worldwide.[16]
• Spherical tokamak: also known as spherical torus. A variation on the tokamak with a spherical shape.
• Stellarator: Twisted rings of hot plasma. The stellarator attempts to create a natural twisted plasma path, using external magnets. Stellarators were developed by Lyman Spitzer in 1950 and evolved into four designs: Torsatron, Heliotron, Heliac and Helias. One example is Wendelstein 7-X, a German device. It is the world's largest stellarator.[17]
• Internal rings: Stellarators create a twisted plasma using external magnets, while tokamaks do so using a current induced in the plasma. Several classes of designs provide this twist using conductors inside the plasma. Early calculations showed that collisions between the plasma and the supports for the conductors would remove energy faster than fusion reactions could replace it. Modern variations, including the Levitated Dipole Experiment (LDX), use a solid superconducting torus that is magnetically levitated inside the reactor chamber.[18]
• Magnetic mirror: Developed by Richard F. Post and teams at LLNL in the 1960s.[19] Magnetic mirrors reflect plasma back and forth in a line. Variations included the Tandem Mirror, magnetic bottle and the biconic cusp.[20] A series of mirror machines were built by the US government in the 1970s and 1980s, principally at LLNL.[21] However, calculations in the 1970s estimated it was unlikely these would ever be commercially useful.
• Bumpy torus: A number of magnetic mirrors are arranged end-to-end in a toroidal ring. Any fuel ions that leak out of one are confined in a neighboring mirror, permitting the plasma pressure to be raised arbitrarily high without loss. An experimental facility, the ELMO Bumpy Torus or EBT was built and tested at Oak Ridge National Laboratory (ORNL) in the 1970s.
• Field-reversed configuration: This device traps plasma in a self-organized quasi-stable structure; where the particle motion makes an internal magnetic field which then traps itself.[22]
• Spheromak: Similar to a field-reversed configuration, a semi-stable plasma structure made by using the plasmas' self-generated magnetic field. A spheromak has both toroidal and poloidal fields, while a field-reversed configuration has no toroidal field.[23]
• Reversed field pinch: Here the plasma moves inside a ring. It has an internal magnetic field. Moving out from the center of this ring, the magnetic field reverses direction.

### Inertial confinement

Plot of NIF results from 2012 to 2021
• Indirect drive: Lasers heat a structure known as a Hohlraum that becomes so hot it begins to radiate x-ray light. These x-rays heat a fuel pellet, causing it to collapse inward to compress the fuel. The largest system using this method is the National Ignition Facility, followed closely by Laser Mégajoule.[24]
• Direct drive: Lasers directly heat the fuel pellet. Notable direct drive experiments have been conducted at the Laboratory for Laser Energetics (LLE) and the GEKKO XII facilities. Good implosions require fuel pellets with close to a perfect shape in order to generate a symmetrical inward shock wave that produces the high-density plasma.
• Fast ignition: This method uses two laser blasts. The first blast compresses the fusion fuel, while the second ignites it. As of 2019 this technique had lost favor for energy production.[25]
• Magneto-inertial fusion or Magnetized Liner Inertial Fusion: This combines a laser pulse with a magnetic pinch. The pinch community refers to it as magnetized liner inertial fusion while the ICF community refers to it as magneto-inertial fusion.[26]
• Ion Beams: Ion beams replace laser beams to heat the fuel.[27] The main difference is that the beam has momentum due to mass, whereas lasers do not. As of 2019 it appears unlikely that ion beams can be sufficiently focused spatially and in time.
• Z-machine: Sends an electrical current through thin tungsten wires, heating them sufficiently to generate x-rays. Like the indirect drive approach, these x-rays then compress a fuel capsule.

### Magnetic or electric pinches

• Z-Pinch: A current travels in the z-direction through the plasma. The current generates a magnetic field that compresses the plasma. Pinches were the first method for man-made controlled fusion.[28][29] The z-pinch has inherent instabilities that limit its compression and heating to values too low for practical fusion. The largest such machine, the UK's ZETA, was the last major experiment of the sort. The problems in z-pinch led to the tokamak design. The dense plasma focus is a possibly superior variation.
• Theta-Pinch: A current circles around the outside of a plasma column, in the theta direction. This induces a magnetic field running down the center of the plasma, as opposed to around it. The early theta-pinch device Scylla was the first to conclusively demonstrate fusion, but later work demonstrated it had inherent limits that made it uninteresting for power production.
• Sheared Flow Stabilized Z-Pinch: Research at the University of Washington under Uri Shumlak investigated the use of sheared-flow stabilization to smooth out the instabilities of Z-pinch reactors. This involves accelerating neutral gas along the axis of the pinch. Experimental machines included the FuZE and Zap Flow Z-Pinch experimental reactors.[30] In 2017, British technology investor and entrepreneur Benj Conway, together with physicists Brian Nelson and Uri Shumlak, co-founded Zap Energy to attempt to commercialize the technology for power production.[31][32][33]
• Screw Pinch: This method combines a theta and z-pinch for improved stabilization.[34]

### Inertial electrostatic confinement

• Fusor: An electric field heats ions to fusion conditions. The machine typically uses two spherical cages, a cathode inside the anode, inside a vacuum. These machines are not considered a viable approach to net power because of their high conduction and radiation losses.[35] They are simple enough to build that amateurs have fused atoms using them.[36]
• Polywell: Attempts to combine magnetic confinement with electrostatic fields, to avoid the conduction losses generated by the cage.[37]

### Other

• Magnetized target fusion: Confines hot plasma using a magnetic field and squeezes it using inertia. Examples include LANL FRX-L machine,[38] General Fusion (piston compression with liquid metal liner), HyperJet Fusion (plasma jet compression with plasma liner).[39][40]
• Uncontrolled: Fusion has been initiated by man, using uncontrolled fission explosions to stimulate fusion. Early proposals for fusion power included using bombs to initiate reactions. See Project PACER.
• Beam fusion: A beam of high energy particles fired at another beam or target can initiate fusion. This was used in the 1970s and 1980s to study the cross sections of fusion reactions.[3] However beam systems cannot be used for power because keeping a beam coherent takes more energy than comes from fusion.
• Muon-catalyzed fusion: This approach replaces electrons in diatomic molecules of isotopes of hydrogen with muons - more massive particles with the same electric charge. Their greater mass compresses the nuclei enough such that the strong interaction can cause fusion.[41] As of 2007 producing muons required more energy than can be obtained from muon-catalyzed fusion.[42]

## Common tools

Many approaches, equipment, and mechanisms are employed across multiple projects to address fusion heating, measurement, and power production.[43]

### Heating

• Electrostatic heating: an electric field can do work on charged ions or electrons, heating them.[44]
• Neutral beam injection: hydrogen is ionized and accelerated by an electric field to form a charged beam that is shone through a source of neutral hydrogen gas towards the plasma which itself is ionized and contained by a magnetic field. Some of the intermediate hydrogen gas is accelerated towards the plasma by collisions with the charged beam while remaining neutral: this neutral beam is thus unaffected by the magnetic field and so reaches the plasma. Once inside the plasma the neutral beam transmits energy to the plasma by collisions which ionize it and allow it to be contained by the magnetic field, thereby both heating and refueling the reactor in one operation. The remainder of the charged beam is diverted by magnetic fields onto cooled beam dumps.[45]
• Radio frequency heating: a radio wave causes the plasma to oscillate (i.e., microwave oven). This is also known as electron cyclotron resonance heating, using for example gyrotrons, or dielectric heating.[46]
• Magnetic reconnection: when plasma gets dense, its electromagnetic properties can change, which can lead to magnetic reconnection. Reconnection helps fusion because it instantly dumps energy into a plasma, heating it quickly. Up to 45% of the magnetic field energy can heat the ions.[47][48]
• Magnetic oscillations: varying electrical currents can be supplied to magnetic coils that heat plasma confined within a magnetic wall.[49]
• Antiproton annihilation: antiprotons injected into a mass of fusion fuel can induce thermonuclear reactions. This possibility as a method of spacecraft propulsion, known as antimatter-catalyzed nuclear pulse propulsion, was investigated at Pennsylvania State University in connection with the proposed AIMStar project.[citation needed]

### Measurement

The diagnostics of a fusion scientific reactor are extremely complex and varied.[50] The diagnostics required for a fusion power reactor will be various but less complicated than those of a scientific reactor as by the time of commercialization, many real-time feedback and control diagnostics will have been perfected. However, the operating environment of a commercial fusion reactor will be harsher for diagnostic systems than in a scientific reactor because continuous operations may involve higher plasma temperatures and higher levels of neutron irradiation. In many proposed approaches, commercialization will require the additional ability to measure and separate diverter gases, for example helium and impurities, and to monitor fuel breeding, for instance the state of a tritium breeding liquid lithium liner.[51] The following are some basic techniques.

• Flux loop: a loop of wire is inserted into the magnetic field. As the field passes through the loop, a current is made. The current measures the total magnetic flux through that loop. This has been used on the National Compact Stellarator Experiment,[52] the polywell,[53] and the LDX machines. A Langmuir probe, a metal object placed in a plasma, can be employed. A potential is applied to it, giving it a voltage against the surrounding plasma. The metal collects charged particles, drawing a current. As the voltage changes, the current changes. This makes an IV Curve. The IV-curve can be used to determine the local plasma density, potential and temperature.[54]
• Thomson scattering: 'Light scatters' from plasma can be used to reconstruct plasma behavior, including density and temperature. It is common in Inertial confinement fusion,[55] Tokamaks,[56] and fusors. In ICF systems, firing a second beam into a gold foil adjacent to the target makes x-rays that traverse the plasma. In tokamaks, this can be done using mirrors and detectors to reflect light.
• Neutron detectors: Several types of neutron detectors can record the rate at which neutrons are produced.[57][58]
• X-ray detectors Visible, IR, UV, and X-rays are emitted anytime a particle changes velocity.[59] If the reason is deflection by a magnetic field, the radiation is cyclotron radiation at low speeds and synchrotron radiation at high speeds. If the reason is deflection by another particle, plasma radiates X-rays, known as Bremsstrahlung radiation.[60]

### Power production

Neutron blankets absorb neutrons, which heats the blanket. Power can be extracted from the blanket in various ways:

• Steam turbines can be driven by heat transferred into a working fluid that turns into steam, driving electric generators.[61]
• Neutron blankets: These neutrons can regenerate spent fission fuel.[62] Tritium can be produced using a breeder blanket of liquid lithium or a helium cooled pebble bed made of lithium-bearing ceramic pebbles.[63]
• Direct conversion: The kinetic energy of a particle can be converted into voltage.[19] It was first suggested by Richard F. Post in conjunction with magnetic mirrors, in the late 1960s. It has been proposed for Field-Reversed Configurations as well as Dense Plasma Focus devices. The process converts a large fraction of the random energy of the fusion products into directed motion. The particles are then collected on electrodes at various large electrical potentials. This method has demonstrated an experimental efficiency of 48 percent.[64]

### Confinement

Parameter space occupied by inertial fusion energy and magnetic fusion energy devices as of the mid-1990s. The regime allowing thermonuclear ignition with high gain lies near the upper right corner of the plot.

Confinement refers to all the conditions necessary to keep a plasma dense and hot long enough to undergo fusion. General principles:

• Equilibrium: The forces acting on the plasma must be balanced. One exception is inertial confinement, where the fusion must occur faster than the dispersal time.
• Stability: The plasma must be constructed so that disturbances will not lead to the plasma dispersing.
• Transport or conduction: The loss of material must be sufficiently slow.[4] The plasma carries energy off with it, so rapid loss of material will disrupt fusion. Material can be lost by transport into different regions or conduction through a solid or liquid.

To produce self-sustaining fusion, part of the energy released by the reaction must be used to heat new reactants and maintain the conditions for fusion.

#### Unconfined

The first human-made, large-scale fusion reaction was the test of the hydrogen bomb, Ivy Mike, in 1952.

#### Magnetic confinement

##### Magnetic Mirror

Magnetic mirror effect. If a particle follows the field line and enters a region of higher field strength, the particles can be reflected. Several devices apply this effect. The most famous was the magnetic mirror machines, a series of devices built at LLNL from the 1960s to the 1980s.[65] Other examples include magnetic bottles and Biconic cusp.[66] Because the mirror machines were straight, they had some advantages over ring-shaped designs. The mirrors were easier to construct and maintain and direct conversion energy capture was easier to implement.[9] Poor confinement led this approach to be abandoned, except in the polywell design.[67]

##### Magnetic Loops

Magnetic loops bend the field lines back on themselves, either in circles or more commonly in nested toroidal surfaces. The most highly developed systems of this type are the tokamak, the stellarator, and the reversed field pinch. Compact toroids, especially the field-reversed configuration and the spheromak, attempt to combine the advantages of toroidal magnetic surfaces with those of a simply connected (non-toroidal) machine, resulting in a mechanically simpler and smaller confinement area.

#### Inertial confinement

Inertial confinement is the use of rapid implosion to heat and confine plasma. A shell surrounding the fuel is imploded using a direct laser blast (direct drive), a secondary x-ray blast (indirect drive), or heavy beams. The fuel must be compressed to about 30 times solid density with energetic beams. Direct drive can in principle be efficient, but insufficient uniformity has prevented success.[68]:19-20 Indirect drive uses beams to heat a shell, driving the shell to radiate x-rays, which then implode the pellet. The beams are commonly laser beams, but ion and electron beams have been investigated.[68]:182-193

##### Electrostatic confinement

Electrostatic confinement fusion devices use electrostatic fields. The best known is the fusor. This device has a cathode inside an anode wire cage. Positive ions fly towards the negative inner cage, and are heated by the electric field in the process. If they miss the inner cage they can collide and fuse. Ions typically hit the cathode, however, creating prohibitory high conduction losses. Fusion rates in fusors are low because of competing physical effects, such as energy loss in the form of light radiation.[69] Designs have been proposed to avoid the problems associated with the cage, by generating the field using a non-neutral cloud. These include a plasma oscillating device,[70] a magnetically shielded-grid,[71] a penning trap, the polywell,[72] and the F1 cathode driver concept.[73]

## Fuels

The fuels considered for fusion power have all been light elements like the isotopes of hydrogen—protium, deuterium, and tritium.[3] The deuterium and helium-3 reaction requires helium-3, an isotope of helium so scarce on Earth that it would have to be mined extraterrestrially or produced by other nuclear reactions. Ultimately, researchers hope to adopt the protium/boron-11 reaction, because it does not directly produce neutrons, although side reactions can.[74]

### Deuterium/tritium

Diagram of the D-T reaction

The easiest nuclear reaction, at the lowest energy, is D+T:

2
1
D
+ 3
1
T
4
2
He
(3.5 MeV) + 1
0
n
(14.1 MeV)

This reaction is common in research, industrial and military applications, usually as a neutron source. Deuterium is a naturally occurring isotope of hydrogen and is commonly available. The large mass ratio of the hydrogen isotopes makes their separation easy compared to the uranium enrichment process. Tritium is a natural isotope of hydrogen, but because it has a short half-life of 12.32 years, it is hard to find, store, produce, and is expensive. Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from lithium using one of the following reactions:

1
0
n
+ 6
3
Li
3
1
T
+ 4
2
He
1
0
n
+ 7
3
Li
3
1
T
+ 4
2
He
+ 1
0
n

The reactant neutron is supplied by the D-T fusion reaction shown above, and the one that has the greatest energy yield. The reaction with 6Li is exothermic, providing a small energy gain for the reactor. The reaction with 7Li is endothermic, but does not consume the neutron. Neutron multiplication reactions are required to replace the neutrons lost to absorption by other elements. Leading candidate neutron multiplication materials are beryllium and lead, but the 7Li reaction helps to keep the neutron population high. Natural lithium is mainly 7Li, which has a low tritium production cross section compared to 6Li so most reactor designs use breeder blankets with enriched 6Li.

Drawbacks commonly attributed to D-T fusion power include:

• The supply of neutrons results in neutron activation of the reactor materials.[75]:242
• 80% of the resultant energy is carried off by neutrons, which limits the use of direct energy conversion.[76]
• It requires the radioisotope tritium. Tritium may leak from reactors. Some estimates suggest that this would represent a substantial environmental radioactivity release.[77]

The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of fission power reactors, posing problems for material design. After a series of D-T tests at JET, the vacuum vessel was sufficiently radioactive that it required remote handling for the year following the tests.[78]

In a production setting, the neutrons would react with lithium in the breeder blanket composed of lithium ceramic pebbles or liquid lithium, yielding tritium. The energy of the neutrons ends up in the lithium, which would then be transferred to drive electrical production. The lithium blanket protects the outer portions of the reactor from the neutron flux. Newer designs, the advanced tokamak in particular, use lithium inside the reactor core as a design element. The plasma interacts directly with the lithium, preventing a problem known as "recycling". The advantage of this design was demonstrated in the Lithium Tokamak Experiment.

### Deuterium

Deuterium fusion cross section (in square meters) at different ion collision energies.

Fusing two deuterium nuclei is the second easiest fusion reaction. The reaction has two branches that occur with nearly equal probability:

 D + D → T + 1H D + D → 3He + n

This reaction is also common in research. The optimum energy to initiate this reaction is 15 keV, only slightly higher than that for the D-T reaction. The first branch produces tritium, so that a D-D reactor is not tritium-free, even though it does not require an input of tritium or lithium. Unless the tritons are quickly removed, most of the tritium produced is burned in the reactor, which reduces the handling of tritium, with the disadvantage of producing more, and higher-energy, neutrons. The neutron from the second branch of the D-D reaction has an energy of only 2.45 MeV (0.393 pJ), while the neutron from the D-T reaction has an energy of 14.1 MeV (2.26 pJ), resulting in greater isotope production and material damage. When the tritons are removed quickly while allowing the 3He to react, the fuel cycle is called "tritium suppressed fusion".[79] The removed tritium decays to 3He with a 12.5 year half life. By recycling the 3He decay into the reactor, the fusion reactor does not require materials resistant to fast neutrons.

Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons would be only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from lithium resources and a somewhat softer neutron spectrum. The disadvantage of D-D compared to D-T is that the energy confinement time (at a given pressure) must be 30 times longer and the power produced (at a given pressure and volume) is 68 times less.[citation needed]

Assuming complete removal of tritium and 3He recycling, only 6% of the fusion energy is carried by neutrons. The tritium-suppressed D-D fusion requires an energy confinement that is 10 times longer compared to D-T and double the plasma temperature.[80]

### Deuterium, helium-3

A second-generation approach to controlled fusion power involves combining helium-3 (3He) and deuterium (2H):

 D + 3He → 4He + 1H

This reaction produces 4He and a high-energy proton. As with the p-11B aneutronic fusion fuel cycle, most of the reaction energy is released as charged particles, reducing activation of the reactor housing and potentially allowing more efficient energy harvesting (via any of several pathways).[81] In practice, D-D side reactions produce a significant number of neutrons, leaving p-11B as the preferred cycle for aneutronic fusion.[81]

### Proton, boron-11

Both material science problems and non proliferation concerns are greatly diminished by aneutronic fusion. Theoretically, the most reactive aneutronic fuel is 3He. However, obtaining reasonable quantities of 3He implies large scale extraterrestrial mining on the moon or in the atmosphere of Uranus or Saturn. Therefore, the most promising candidate fuel for such fusion is fusing the readily available protium (i.e. a proton) and boron. Their fusion releases no neutrons, but produces energetic charged alpha (helium) particles whose energy can directly be converted to electrical power:

p + 11B → 3 4He

Side reactions are likely to yield neutrons that carry only about 0.1% of the power,[82]:177-182 which means that neutron scattering is not used for energy transfer and material activation is reduced several thousand-fold. The optimum temperature for this reaction of 123 keV[83] is nearly ten times higher than that for pure hydrogen reactions, and energy confinement must be 500 times better than that required for the D-T reaction. In addition, the power density is 2500 times lower than for D-T, although per unit mass of fuel, this is still considerably higher than for fission reactors.

Because the confinement properties of the tokamak and laser pellet fusion are marginal, most proposals for aneutronic fusion are based on radically different confinement concepts, such as the Polywell and the Dense Plasma Focus. In 2013, a research team led by Christine Labaune at École Polytechnique, reported a new fusion rate record for proton-boron fusion, with an estimated 80 million fusion reactions during a 1.5 nanosecond laser fire, 100x previous experiments.[84][85]

## Material selection

Structural material stability is a critical issue.[86][87] Materials that can survive the high temperatures and neutron bombardment experienced in a fusion reactor are considered key to success.[88][86] The principal issues are the conditions generated by the plasma, neutron degradation of wall surfaces, and the related issue of plasma-wall surface conditions.[89][90] Reducing hydrogen permeability is seen as crucial to hydrogen recycling[91] and control of the tritium inventory.[92] Materials with the lowest bulk hydrogen solubility and diffusivity provide the optimal candidates for stable barriers. A few pure metals, including tungsten and beryllium, and compounds such as carbides, dense oxides, and nitrides have been investigated. Research has highlighted that coating techniques for preparing well-adhered and perfect barriers are of equivalent importance. The most attractive techniques are those in which an ad-layer is formed by oxidation alone. Alternative methods utilize specific gas environments with strong magnetic and electric fields. Assessment of barrier performance represents an additional challenge. Classical coated membranes gas permeation continues to be the most reliable method to determine hydrogen permeation barrier (HPB) efficiency.[92] In 2021, in response to increasing numbers of designs for fusion power reactors for 2040, the United Kingdom Atomic Energy Authority published the UK Fusion Materials Roadmap 2021-2040, focusing on five priority areas, with a focus on tokamak family reactors:

• Novel materials to minimize the amount of activation in the structure of the fusion power plant;
• Compounds that can be used within the power plant to optimise breeding of tritium fuel to sustain the fusion process;
• Magnets and insulators that are resistant to irradiation from fusion reactions – especially under cryogenic conditions;
• Structural materials able to retain their strength under neutron bombardment at high operating temperatures (over 550 degrees C);
• Engineering assurance for fusion materials – providing irradiated sample data and modelled predictions such that plant designers, operators and regulators have confidence that materials are suitable for use in future commercial power stations.

### Superconducting materials

SuperOx was able to produce over 186 miles of YBCO in 9 months for use in fusion reactor magnet, dramatically surpassing the companies previous production targets.

In a plasma that is embedded in a magnetic field (known as a magnetized plasma) the fusion rate scales as the magnetic field strength to the 4th power. For this reason, many fusion companies that rely on magnetic fields to control their plasma are trying to develop high temperature superconducting devices. In 2021, SuperOx, a Russian and Japanese company, developed a new manufacturing process for making superconducting YBCO wire for fusion reactors. This new wire was shown to conduct between 700 and 2000 Amps per square millimeter. The company was able to produce 186 miles of wire in 9 months.[93]

### Containment considerations

Even on smaller production scales, the containment apparatus is blasted with matter and energy. Designs for plasma containment must consider:

Depending on the approach, these effects may be higher or lower than fission reactors.[94] One estimate put the radiation at 100 times that of a typical pressurized water reactor.[citation needed] Depending on the approach, other considerations such as electrical conductivity, magnetic permeability, and mechanical strength matter. Materials must also not end up as long-lived radioactive waste.[86]

### Plasma-wall surface conditions

For long term use, each atom in the wall is expected to be hit by a neutron and displaced about 100 times before the material is replaced. High-energy neutrons produce hydrogen and helium via nuclear reactions that tend to form bubbles at grain boundaries and result in swelling, blistering or embrittlement.[94]

### Selection of materials

Low-Z materials, such as graphite or beryllium are generally preferred to high-Z materials, usually tungsten with molybdenum as a second choice.[92] Liquid metals (lithium, gallium, tin) have been proposed, e.g., by injection of 1–5 mm thick streams flowing at 10 m/s on solid substrates.[citation needed]

Graphite features a gross erosion rate due to physical and chemical sputtering amounting to many meters per year, requiring redeposition of the sputtered material. The redeposition site generally does not exactly match the sputter site, allowing net erosion that may be prohibitive. An even larger problem is that tritium is redeposited with the redeposited graphite. The tritium inventory in the wall and dust could build up to many kilograms, representing a waste of resources and a radiological hazard in case of an accident. Graphite found favor as material for short-lived experiments, but appears unlikely to become the primary plasma-facing material (PFM) in a commercial reactor.[86]

Tungsten's sputtering rate is orders of magnitude smaller than carbon's, and tritium is much less incorporated into redeposited tungsten. However, tungsten plasma impurities are much more damaging than carbon impurities, and self-sputtering can be high, requiring the plasma in contact with the tungsten not be too hot (a few tens of eV rather than hundreds of eV). Tungsten also has issues around eddy currents and melting in off-normal events, as well as some radiological issues.[86]

## Safety and the environment

### Accident potential

Fusion reactors are not subject to catastrophic meltdown.[95] It requires precise and controlled temperature, pressure and magnetic field parameters to produce net energy, and any damage or loss of required control would rapidly quench the reaction.[96] Fusion reactors operate with seconds or even microseconds worth of fuel at any moment. Without active refueling, the reactions immediately quench.[95]

The same constraints prevent runaway reactions. Although the plasma is expected to have a volume of 1,000 m3 (35,000 cu ft) or more, the plasma typically contains only a few grams of fuel.[95] By comparison, a fission reactor is typically loaded with enough fuel for months or years, and no additional fuel is necessary to continue the reaction. This large fuel supply is what offers the possibility of a meltdown.[97]

In magnetic containment, strong fields develop in coils that are mechanically held in place by the reactor structure. Failure of this structure could release this tension and allow the magnet to "explode" outward. The severity of this event would be similar to other industrial accidents or an MRI machine quench/explosion, and could be effectively contained within a containment building similar to those used in fission reactors.

In laser-driven inertial containment the larger size of the reaction chamber reduces the stress on materials. Although failure of the reaction chamber is possible, stopping fuel delivery prevents catastrophic failure.[98]

Most reactor designs rely on liquid hydrogen as a coolant and to convert stray neutrons into tritium, which is fed back into the reactor as fuel. Hydrogen is flammable, and it is possible that hydrogen stored on-site could ignite. In this case, the tritium fraction of the hydrogen would enter the atmosphere, posing a radiation risk. Calculations suggest that about 1 kilogram (2.2 lb) of tritium and other radioactive gases in a typical power station would be present. The amount is small enough that it would dilute to legally acceptable limits by the time they reached the station's perimeter fence.[99]

The likelihood of small industrial accidents, including the local release of radioactivity and injury to staff, are estimated to be minor compared to fission. They would include accidental releases of lithium or tritium or mishandling of radioactive reactor components.[98]

### Magnet quench

A magnet quench is an abnormal termination of magnet operation that occurs when part of the superconducting coil exits the superconducting state (becomes normal). This can occur because the field inside the magnet is too large, the rate of change of field is too large (causing eddy currents and resultant heating in the copper support matrix), or a combination of the two.

More rarely a magnet defect can cause a quench. When this happens, that particular spot is subject to rapid Joule heating from the current, which raises the temperature of the surrounding regions. This pushes those regions into the normal state as well, which leads to more heating in a chain reaction. The entire magnet rapidly becomes normal over several seconds, depending on the size of the superconducting coil. This is accompanied by a loud bang as the energy in the magnetic field is converted to heat, and the cryogenic fluid boils away. The abrupt decrease of current can result in kilovolt inductive voltage spikes and arcing. Permanent damage to the magnet is rare, but components can be damaged by localized heating, high voltages, or large mechanical forces.

In practice, magnets usually have safety devices to stop or limit the current when a quench is detected. If a large magnet undergoes a quench, the inert vapor formed by the evaporating cryogenic fluid can present a significant asphyxiation hazard to operators by displacing breathable air.

A large section of the superconducting magnets in CERN's Large Hadron Collider unexpectedly quenched during start-up operations in 2008, destroying multiple magnets.[100] In order to prevent a recurrence, the LHC's superconducting magnets are equipped with fast-ramping heaters that are activated when a quench event is detected. The dipole bending magnets are connected in series. Each power circuit includes 154 individual magnets, and should a quench event occur, the entire combined stored energy of these magnets must be dumped at once. This energy is transferred into massive blocks of metal that heat up to several hundred degrees Celsius—because of resistive heating—in seconds. A magnet quench is a "fairly routine event" during the operation of a particle accelerator.[101]

### Effluents

The natural product of the fusion reaction is a small amount of helium, which is harmless to life. Hazardous tritium is difficult to retain completely. During normal operation, tritium is continually released.[98]

Although tritium is volatile and biologically active, the health risk posed by a release is much lower than that of most radioactive contaminants, because of tritium's short half-life (12.32 years) and very low decay energy (~14.95 keV), and because it does not bioaccumulate (it cycles out of the body as water, with a biological half-life of 7 to 14 days).[102] ITER incorporates total containment facilities for tritium.[103]

The choice of materials is less constrained than in conventional fission, where many materials are required for their specific neutron cross-sections. Fusion reactors can be designed using "low activation", materials that do not easily become radioactive. Vanadium, for example, becomes much less radioactive than stainless steel.[108] Carbon fiber materials are also low-activation, and are strong and light, and are promising for laser-inertial reactors where a magnetic field is not required.[109]

### Nuclear proliferation

Fusion's overlap with nuclear weapons is limited. A huge amount of tritium could be produced by a fusion power station; tritium is used in the trigger of hydrogen bombs and in modern boosted fission weapons, but it can be produced in other ways. The energetic neutrons from a fusion reactor could be used to breed weapons-grade plutonium or uranium for an atomic bomb (for example by transmutation of 238
U
to 239Pu, or 232
Th
to 233
U
).

A study conducted in 2011 assessed three scenarios:[110]

• Small-scale fusion station: As a result of much higher power consumption, heat dissipation and a more recognizable design compared to enrichment gas centrifuges, this choice would be much easier to detect and therefore implausible.[110]
• Commercial facility: The production potential is significant. But no fertile or fissile substances necessary for the production of weapon-usable materials needs to be present at a civil fusion system at all. If not shielded, detection of these materials can be done by their characteristic gamma radiation. The underlying redesign could be detected by regular design information verification. In the (technically more feasible) case of solid breeder blanket modules, it would be necessary for incoming components to be inspected for the presence of fertile material,[110] otherwise plutonium for several weapons could be produced each year.[111]
• Prioritizing weapon-grade material regardless of secrecy: The fastest way to produce weapon-usable material was seen in modifying a civil fusion power station. No weapons-compatible material is required during civil use. Even without the need for covert action, such a modification would take about 2 months to start production and at least an additional week to generate a significant amount. This was considered to be enough time to detect a military use and to react with diplomatic or military means. To stop the production, a military destruction of parts of the facility while leaving out the reactor would be sufficient.[110]

Another study concluded "...large fusion reactors – even if not designed for fissile material breeding – could easily produce several hundred kg Pu per year with high weapon quality and very low source material requirements." It was emphasized that the implementation of features for intrinsic proliferation resistance might only be possible at an early phase of research and development.[111] The theoretical and computational tools needed for hydrogen bomb design are closely related to those needed for inertial confinement fusion, but have very little in common with magnetic confinement fusion.

### Fuel reserves

Fusion power commonly proposes the use of deuterium as fuel and many current designs also use lithium. Assuming a fusion energy output equal to the 1995 global power output of about 100 EJ/yr (= 1 × 1020 J/yr) and that this does not increase in the future, which is unlikely, then known current lithium reserves would last 3000 years. Lithium from sea water would last 60 million years, however, and a more complicated fusion process using only deuterium would have fuel for 150 billion years.[112] To put this in context, 150 billion years is close to 30 times the remaining lifespan of the sun,[113] and more than 10 times the estimated age of the universe.

## Economics

The EU spent almost €10 billion through the 1990s.[114] ITER represents an investment of over twenty billion dollars, and possibly tens of billions more, including in kind contributions.[115][116] Under the European Union's Sixth Framework Programme, nuclear fusion research received €750 million (in addition to ITER funding), compared with €810 million for sustainable energy research,[117] putting research into fusion power well ahead of that of any single rival technology. The United States Department of Energy has allocated $US367M–$US671M every year since 2010, peaking in 2020,[118] with plans to reduce investment to $US425M in its FY2021 Budget Request.[119] About a quarter of this budget is directed to support ITER. The size of the investments and time lines results mean that fusion research has almost exclusively been publicly funded. However, in recent years, the promise of commercializing a paradigm-changing low carbon energy source has attracted a raft of companies and investors.[120] Over two dozen start-up companies attracted over one billion dollars from roughly 2000 to 2020, mainly from 2015, and a further three billion in funding and milestone related commitments in 2021,[121][122] with investors including Jeff Bezos, Peter Thiel and Bill Gates, as well as institutional investors including Legal & General, and energy companies including Equinor, Eni, Chevron,[123] and the Chinese ENN Group.[124][125][126] Recently, private fusion companies have attracted investment in the billions of dollars. For example, in 2021, Commonwealth Fusion Systems (CFS) obtained$1.8 billion in scale-up funding, and Helion Energy obtained a half-billion dollars with an additional $1.7 billion contingent on meeting milestones.[127] Scenarios developed in the 2000s and early 2010s discussed the effects of the commercialization of fusion power on the future of human civilization.[128] Using nuclear fission as a guide, these saw ITER and later DEMO as bringing online the first commercial reactors around 2050 and a rapid expansion after mid-century.[128] Some scenarios emphasized 'fusion nuclear science facilities' as a step beyond ITER.[129][130] However, the economic obstacles to tokamak-based fusion power remain immense, requiring investment to fund prototype tokamak reactors[131] and development of new supply chains.[132] Tokamak designs appear to be labour-intensive,[133] while the commercialization risk of alternatives like inertial fusion energy is high due to the lack of government resources.[134] Scenarios since 2010 note computing and material science advances enabling multi-phase national or cost-sharing 'Fusion Pilot Plants' (FPPs) along various technology pathways,[135][130][136][137][138][139] such as the UK Spherical Tokamak for Energy Production, within the 2030-2040 time frame.[140][141][142] Notably, in June 2021, General Fusion announced it would accept the UK government's offer to host the world's first substantial public-private partnership fusion demonstration plant, at Culham Centre for Fusion Energy.[143] The plant will be constructed from 2022 to 2025 and is intended to lead the way for commercial pilot plants in the late 2025s. The plant will be 70% of full scale and is expected to attain a stable plasma of 150 million degrees.[144] In the United States, cost-sharing public-private partnership FPPs appear likely.[145] Compact reactor technology based on such demonstration plants may enable commercialization via a fleet approach from the 2030s[146] if early markets can be located.[142] The widespread adoption of non-nuclear renewable energy has transformed the energy landscape. Such renewables are projected to supply 74% of global energy by 2050.[147] The steady fall of renewable energy prices challenges the economic competitiveness of fusion power.[148] Levelized cost of energy (LCOE) for various sources of energy including wind, solar and nuclear energy. Some economists suggest fusion power is unlikely to match other renewable energy costs.[148] Fusion plants are expected to face large start up and capital costs. Moreover, operation and maintenance are likely to be costly.[148] While the costs of the CFETR are not well known, an EU DEMO fusion concept was projected to feature a levelized cost of energy (LCOE) of$121/MWh.[149]

Furthermore, economists suggest that fusion energy cost increases by $16.5/ MWh for every$1 billion increase in the price of fusion technology.[148] This high Levelized cost of energy is largely a result of construction costs.[148]

## Geopolitics

Given the potential of fusion to transform the world's energy industry and mitigate climate change,[161][162] fusion science has traditionally been seen as an integral part of peace-building science diplomacy.[163][103] However, technological developments[164] and private sector involvement has raised concerns over intellectual property, regulatory administration, global leadership;[161] equity, and potential weaponization.[126][165] These challenge ITER's peace-building role and led to calls for a global commission.[165][166] Fusion power significantly contributing to climate change by 2050 seems unlikely without substantial breakthroughs and a space race mentality emerging,[136][167] but a contribution by 2100 appears possible, with the extent depending on the type and particularly cost of technology pathways.[168][169]

Developments from late 2020 onwards have led to talk of a "new space race" with multiple entrants, pitting the US against China[40] and the UK's STEP FPP.[170][171] On 24 September, the United States House of Representatives approved a research and commercialization program. The Fusion Energy Research section incorporated a milestone-based, cost-sharing, public-private partnership program modeled on NASA's COTS program, which launched the commercial space industry.[123] In February 2021, the National Academies published Bringing Fusion to the U.S. Grid, recommending a market-driven, cost-sharing plant for 2035–2040,[172][173][174] and the launch of the Congressional Bipartisan Fusion Caucus followed.[175]

In December 2020, an independent expert panel reviewed EUROfusion's design and R&D work on DEMO, and EUROfusion confirmed it was proceeding with its Roadmap to Fusion Energy, beginning the conceptual design of DEMO in partnership with the European fusion community, suggesting an EU-backed machine had entered the race.[176]

Fusion power promised to provide more energy for a given weight of fuel than any fuel-consuming energy source currently in use.[177] The fuel (primarily deuterium) exists abundantly in the ocean: about 1 in 6500 hydrogen atoms in seawater is deuterium.[178] Although this is only about 0.015%, seawater is plentiful and easy to access, implying that fusion could supply the world's energy needs for millions of years.[179][180]

First generation fusion plants are expected to use the deuterium-tritium fuel cycle. This will require the use of lithium for breeding of the tritium. It is not known for how long global lithium supplies will suffice to supply this need as well as those of the battery and metallurgical industries. It is expected that second generation plants will move on to the more formidable deuterium-deuterium reaction. The deuterium-helium-3 reaction is also of interest, but the light helium isotope is practically non-existent on Earth. It is thought to exist in useful quantities in the lunar regolith, and is abundant in the atmospheres of the gas giant planets.

Fusion power could be used for so-called 'deep space' propulsion within the solar system[181][182] and for interstellar space exploration where solar energy is not available, including via antimatter-fusion hybrid drives.[183][184]

## History

The history of fusion power began early in the 20th century as an inquiry into how stars powered themselves and expanded to incorporate a broad inquiry into the nature of matter and energy, while potential applications expanded to include warfare, rocket propulsion, and energy production. Unfortunately, generating electricity from fusion has been forecast to be 30 years in the future for the last 50 years and may still be that far off.[185]

The history is a convoluted mixture of investigations into nuclear physics and a parallel exploration of engineering challenges ranging from identifying appropriate materials and fuels, to improving heating and confinement techniques.

The first man-made device to achieve ignition was the detonation of this fusion device, codenamed Ivy Mike.

Early photo of plasma inside a pinch machine (Imperial College 1950–1951)

The quest for fusion power has proceeded along multiple trajectories since the outset. Trajectories such as pinch designs fell away as they confronted obstacles that have yet to be surmounted. The survivors include magnetic confinement approaches such as tokamak and stellarator, along with ICF devices approaches such as laser and electrostatic confinement.

The first successful man-made fusion device was the boosted fission weapon tested in 1951 in the Greenhouse Item test. The first true fusion weapon was 1952's Ivy Mike, and the first practical example was 1954's Castle Bravo.

### Early projects

#### Stellarator

The stellarator was the first candidate, preceding the better-known tokamak. It was pioneered by Lyman Spitzer. While fusion did not immediately transpire, the effort led to the creation of the Princeton Plasma Physics Laboratory.[186][187]

The first experiment to achieve controlled thermonuclear fusion was accomplished using Scylla I at LANL in 1958.[29] Scylla I was a θ-pinch machine, with a cylinder full of deuterium.[28][29]

#### Tokamak

The concept of the tokamak originated in 1950–1951 from I.E. Tamm and A.D. Sakharov in the Soviet Union. The tokamak essentially combined a low-power pinch device with a low-power stellarator.[163]

A.D. Sakharov's group constructed the first tokamaks, achieving the first quasistationary fusion reaction.[188]:90

#### Inertial confinement

Laser fusion was suggested in 1962 by scientists at Lawrence Livermore National Laboratory (LLNL), shortly after the invention of the laser in 1960. Inertial confinement fusion (using lasers) research began as early as 1965.

Shiva laser, 1977, the largest ICF laser system built in the seventies
The Tandem Mirror Experiment (TMX) in 1979

Several laser systems were built at LLNL. These included the Argus, the Cyclops, the Janus, the long path, the Shiva laser, and the Nova.[189]

Laser advances included frequency-tripling crystals that transformed infrared laser beams into ultraviolet beams and "chirping", which changed a single wavelength into a full spectrum that could be amplified and then reconstituted into one frequency.[190] Laser research ate money as well, consuming over one billion dollars in the 1980s.[191]

#### Evolution

Over time the "advanced tokamak" concept emerged, which included non-circular plasma, internal diverters and limiters, superconducting magnets, and operation in the so-called "H-mode" island of increased stability.[192] The compact tokamak, with the magnets on the inside of the vacuum chamber.[193][194]

Magnetic mirrors suffered from end losses, requiring high power, complex magnetic designs, such as the baseball coil pictured here.
The Novette target chamber (metal sphere with diagnostic devices protruding radially), which was reused from the Shiva project and two newly built laser chains visible in background.
Inertial confinement fusion implosion on the Nova laser during the 1980s was a key driver of fusion development.

#### 1980s

The Tore Supra, JET, T-15, and JT-60 tokamaks were built in the 1980s.[195][196] In 1984, Martin Peng of ORNL proposed the spherical tokamak with a much smaller radius.[197] It used a single large conductor in the center, with magnets as half-rings off of this conductor. The aspect ratio fell to as low as 1.2.[198]:B247[199]:225 Peng's advocacy caught the interest of Derek Robinson, who built the Small Tight Aspect Ratio Tokamak, (START).[198]

### 1990s

In 1991, the Preliminary Tritium Experiment at the Joint European Torus achieved the world's first controlled release of fusion power.[200]

In 1996, Tore Supra created a plasma for two minutes with a current of almost 1 million amperes, totaling 280 MJ of injected and extracted energy.[201]

In 1997, JET produced a peak of 16.1 MW of fusion power (65% of heat to plasma,[202]) with fusion power of over 10 MW sustained for over 0.5 sec.[203]

### 2000s

The Mega Ampere Spherical Tokamak became operational in the UK in 1999

"Fast ignition"[204][205] saved power and moved ICF into the race for energy production.

In 2006 China's EAST test reactor was completed.[206] It was the first tokamak to use superconducting magnets to generate both toroidal and poloidal fields.

In March 2009, the laser-driven ICF NIF became operational.[207]

In the 2000s privately backed fusion companies entered the race, including Tri Alpha Energy,[208] General Fusion,[209][210] and Tokamak Energy.[211]

### 2010s

The preamplifiers of the National Ignition Facility. In 2012, the NIF achieved a 500-terawatt shot.

The Wendelstein7X under construction

Example of a stellarator design: A coil system (blue) surrounds plasma (yellow). A magnetic field line is highlighted in green on the yellow plasma surface.

Private and public research accelerated in the 2010s. General Fusion developed plasma injector technology and Tri Alpha Energy tested its C-2U device.[212] The French Laser Mégajoule began operation. NIF achieved net energy gain[213] in 2013, as defined in the very limited sense as the hot spot at the core of the collapsed target, rather than the whole target.[214]

In 2014, Phoenix Nuclear Labs sold a high-yield neutron generator that could sustain 5×1011 deuterium fusion reactions per second over a 24-hour period.[215]

In 2015, MIT announced a tokamak it named the ARC fusion reactor, using rare-earth barium-copper oxide (REBCO) superconducting tapes to produce high-magnetic field coils that it claimed could produce comparable magnetic field strength in a smaller configuration than other designs.[216] In October, researchers at the Max Planck Institute of Plasma Physics completed building the largest stellarator to date, the Wendelstein 7-X. It soon produced helium and hydrogen plasmas lasting up to 30 minutes.[217]

In 2017 Helion Energy's fifth-generation plasma machine went into operation.[218] The UK's Tokamak Energy's ST40 generated "first plasma".[219] The next year, Eni announced a $50 million investment in Commonwealth Fusion Systems, to attempt to commercialize MIT's ARC technology.[220][221][222][223] ### 2020s In January 2021, SuperOx announced the commercialization of a new superconducting wire with more than 700 A/mm2 current capability.[224] TAE Technologies announced results for its Norman device, holding a temperature of about 60 million °C (108 million °F) for 30 milliseconds, 8 and 10 times higher, respectively, than the company's previous devices.[225] In October, Oxford-based First Light Fusion revealed its projectile fusion project, which fires an aluminum disc at a fusion target, accelerated by a 9 mega-amp electrical pulse, reaching speeds of 20 kilometres per second (12 mi/s). The resulting fusion generates neutrons whose energy is captured as heat.[226] On November 8, in an invited talk to the 63rd Annual Meeting of the APS Division of Plasma Physics,[227] the National Ignition Facility claimed[228] to have triggered fusion ignition in the laboratory on August 8, 2021, for the first time in the 60+ year history of the ICF program.[229][230] The shot yielded 1.3 Megajoules of fusion energy, an over 8X improvement on tests done in spring of 2021.[228] NIF estimates that 230 kilo-joules of energy reached the fuel capsule, which resulted in an almost 6-fold energy output from the capsule.[228] A researcher from Imperial College London stated that the majority of the field agreed that ignition had been demonstrated.[228] Researchers at NIF has since been trying to replicate the August result, so far without success.[231] In November 2021, Helion Energy reported receiving$0.5 billion in Series E funding for its seventh-generation Polaris device, designed to demonstrate net electricity production, with an additional $1.7 billion of commitments tied to specific milestones,[232] while Commonwealth Fusion Systems raised an additional$1.8 billion in Series B funding to construct and operate its SPARC reactor, the single largest investment in any private fusion company.[233]

In April 2022, First Light announced that their hypersonic projectile fusion prototype had produced neutrons compatible with fusion. Their technique electromagnetically fires projectiles at Mach 19 at a caged fuel pellet. The deuterium fuel is compressed at Mach 204, reaching pressure levels 100 terapascals.[234]

## Records

Records
Domain Year Record Device Notes
Plasma temperature 2012 1.8 billion kelvin Focus-Fusion 1[235][236]
Fusion power 1997 16 MW JET[237]
Tokamak fusion energy 2022 59 MJ JET[238] More overall energy than the 1997 record but less power as focus was on sustained length
ICF fusion energy 2021 1.3 MJ National Ignition Facility[239]
Plasma pressure 2016 2.05 atmospheres Alcator C-Mod[240]
Lawson criterion 2013 1.53×1021 keV.s.m−3 JT-60 .[241][242]
Fusion energy gain factor Q 1997 0.69 Joint European Torus (JET) 16 MW of power compared to the 23 MW of plasma heating.[237]
Confinement time (field reversed configuration) 2016 300 ms Princeton Field Reversed Configuration[243] Fusion was not observed.
Confinement time (stellarator) 2019 100 s Wendelstein 7-X[244][245]
Confinement time (tokamak) 2022 17 minutes EAST[246]
Confinement time x temperature (tokamak) 2021 12×109 EAST[247]
Beta 1998 0.4 Small Tight Aspect Ratio Tokamak[248]
Temperature (compact spherical tokamak) 2022 100M Tokamak Energy[249]
Temperature x time (tokamak) 2021 100M x 30 seconds KSTAR[250]

## References

1. ^ "Nuclear Fusion : WNA". world-nuclear.org. November 2015. Archived from the original on 2015-07-19. Retrieved 2015-07-26.
2. ^ "Fission and fusion can yield energy". Hyperphysics.phy-astr.gsu.edu. Retrieved 2014-10-30.
3. ^ a b c Miley, G.H.; Towner, H.; Ivich, N. (June 17, 1974). Fusion cross sections and reactivities (Technical Report). doi:10.2172/4014032. OSTI 4014032 – via Osti.gov.
4. Lawson, J D (December 1, 1956). "Some Criteria for a Power Producing Thermonuclear Reactor". Proceedings of the Physical Society. Section B. IOP Publishing. 70 (1): 6–10. doi:10.1088/0370-1301/70/1/303. ISSN 0370-1301.
5. ^ "Lawson's three criteria". EFDA. February 25, 2013. Archived from the original on 2014-09-11. Retrieved 2014-08-24.
6. ^ "Triple product". EFDA. June 20, 2014. Archived from the original on 2014-09-11. Retrieved 2014-08-24.
7. ^ Chiocchio, Stefano. "ITER and the International ITER and the International Scientific Collaboration" (PDF).
8. ^ "Laser Inertial Fusion Energy". Life.llnl.gov. Archived from the original on 2014-09-15. Retrieved 2014-08-24.
9. ^ a b Barr, W. L.; Moir, R. W.; Hamilton, G. W. (1982). "Experimental results from a beam direct converter at 100 kV". Journal of Fusion Energy. Springer Science and Business Media LLC. 2 (2): 131–143. Bibcode:1982JFuE....2..131B. doi:10.1007/bf01054580. ISSN 0164-0313. S2CID 120604056.
10. ^ Fitzpatrick, Richard (August 2014). Plasma physics: an introduction. Boca Raton. ISBN 978-1-4665-9426-5. OCLC 900866248.
11. ^ Alfvén, H (1942). "Existence of electromagnetic-hydrodynamic waves". Nature. 150 (3805): 405–406. Bibcode:1942Natur.150..405A. doi:10.1038/150405d0. S2CID 4072220.
12. ^ Tuszewski, M. (1988). "Field reversed configurations". Nuclear Fusion (Submitted manuscript). 28 (11): 2033–2092. doi:10.1088/0029-5515/28/11/008.
13. ^ Sijoy, C.D.; Chaturvedi, Shashank (2012). "An Eulerian MHD model for the analysis of magnetic flux compression by expanding diamagnetic fusion plasma sphere". Fusion Engineering and Design. 87 (2): 104–117. doi:10.1016/j.fusengdes.2011.10.012. ISSN 0920-3796.
14. ^ Post, R.F. (1958). United Nations International Conference on the Peaceful Uses of Atomic Energy (ed.). Proceedings of the second United Nations International Conference on the Peaceful Uses of Atomic Energy held in Geneva 1 September - 13 September 1958. Vol. 32, Vol. 32. Geneva: United Nations. OCLC 643589395.
15. ^ Katwala, Amit (February 16, 2022). "DeepMind Has Trained an AI to Control Nuclear Fusion". Wired. ISSN 1059-1028. Retrieved 2022-02-17.
16. ^ "All-the-Worlds-Tokamaks". www.tokamak.info. Retrieved 2020-10-11.
17. ^ "The first plasma: the Wendelstein 7-X fusion device is now in operation". www.ipp.mpg.de. Retrieved 2020-10-11.
18. ^ Chandler, David. "MIT tests unique approach to fusion power". MIT News | Massachusetts Institute of Technology. Retrieved 2020-10-11.
19. ^ a b Post, R. F. (January 1, 1970), "Mirror systems: fuel cycles, loss reduction and energy recovery", Nuclear fusion reactors, Conference Proceedings, Thomas Telford Publishing, pp. 99–111, doi:10.1680/nfr.44661, ISBN 978-0-7277-4466-1, retrieved 2020-10-11
20. ^ Berowitz, J.; Grad, H.; Rubin, H. (1958). Proceedings of the second United Nations International Conference on the Peaceful Uses of Atomic Energy. Vol. 31, Vol. 31. Geneva: United Nations. OCLC 840480538.
21. ^ Bagryansky, P. A.; Shalashov, A. G.; Gospodchikov, E. D.; Lizunov, A. A.; Maximov, V. V.; Prikhodko, V. V.; Soldatkina, E. I.; Solomakhin, A. L.; Yakovlev, D. V. (May 18, 2015). "Threefold Increase of the Bulk Electron Temperature of Plasma Discharges in a Magnetic Mirror Device". Physical Review Letters. 114 (20): 205001. arXiv:1411.6288. Bibcode:2015PhRvL.114t5001B. doi:10.1103/physrevlett.114.205001. ISSN 0031-9007. PMID 26047233. S2CID 118484958.
22. ^ Freidberg, Jeffrey P. (February 8, 2007). Plasma Physics and Fusion Energy. Cambridge University Press. ISBN 978-0-521-85107-7.
23. ^ Dolan, Thomas J., ed. (2013). Magnetic Fusion Technology. Lecture Notes in Energy Lne. Lecture Notes in Energy. Vol. 19. London: Springer London. pp. 30–40. doi:10.1007/978-1-4471-5556-0. ISBN 978-1-4471-5555-3. ISSN 2195-1284.
24. ^ Nuckolls, John; Wood, Lowell; Thiessen, Albert; Zimmerman, George (1972). "Laser Compression of Matter to Super-High Densities: Thermonuclear (CTR) Applications". Nature. 239 (5368): 139–142. Bibcode:1972Natur.239..139N. doi:10.1038/239139a0. S2CID 45684425.
25. ^ TURRELL, ARTHUR (2021). HOW TO BUILD A STAR: the science of nuclear fusion and the quest to harness its power. Place of publication not identified: WEIDENFELD & NICOLSON. ISBN 978-1-4746-1159-6. OCLC 1048447399.
26. ^ Thio, Y C F (April 1, 2008). "Status of the US program in magneto-inertial fusion". Journal of Physics: Conference Series. IOP Publishing. 112 (4): 042084. Bibcode:2008JPhCS.112d2084T. doi:10.1088/1742-6596/112/4/042084. ISSN 1742-6596.
27. ^ Sharp, W. M.; et al. (2011). Inertial Fusion Driven by Intense Heavy-Ion Beams (PDF). Proceedings of 2011 Particle Accelerator Conference. New York, NY, USA. p. 1386. Archived from the original (PDF) on 2017-11-26. Retrieved 2019-08-03.
28. ^ a b Seife, Charles (2008). Sun in a bottle : the strange history of fusion and the science of wishful thinking. New York: Viking. ISBN 978-0-670-02033-1. OCLC 213765956.
29. ^ a b c Phillips, James (1983). "Magnetic Fusion". Los Alamos Science: 64–67. Archived from the original on 2016-12-23. Retrieved 2013-04-04.
30. ^ "Flow Z-Pinch Experiments". Aeronautics and Astronautics. November 7, 2014. Retrieved 2020-10-11.
31. ^ "Zap Energy". Zap Energy. Archived from the original on 2020-02-13. Retrieved 2020-02-13.
32. ^ "Board of Directors". ZAP ENERGY. Retrieved 2020-09-08.
33. ^ "Chevron announces investment in nuclear fusion start-up Zap Energy". Power Technology | Energy News and Market Analysis. August 13, 2020. Retrieved 2020-09-08.
34. ^ Srivastava, Krishna M.; Vyas, D. N. (1982). "Non-linear analysis of the stability of the Screw Pinch". Astrophysics and Space Science. Springer Nature. 86 (1): 71–89. Bibcode:1982Ap&SS..86...71S. doi:10.1007/bf00651831. ISSN 0004-640X. S2CID 121575638.
35. ^ Rider, Todd H. (1995). "A general critique of inertial-electrostatic confinement fusion systems". Physics of Plasmas. AIP Publishing. 2 (6): 1853–1872. Bibcode:1995PhPl....2.1853R. doi:10.1063/1.871273. hdl:1721.1/29869. ISSN 1070-664X.
36. ^ Clynes, Tom (February 14, 2012). "The Boy Who Played With Fusion". Popular Science. Retrieved 2019-08-03.
37. ^ US patent 5,160,695, Robert W. Bussard, "Method and apparatus for creating and controlling nuclear fusion reactions", issued 1992-11-03
38. ^ Taccetti, J. M.; Intrator, T. P.; Wurden, G. A.; Zhang, S. Y.; Aragonez, R.; Assmus, P. N.; Bass, C. M.; Carey, C.; deVries, S. A.; Fienup, W. J.; Furno, I. (September 25, 2003). "FRX-L: A field-reversed configuration plasma injector for magnetized target fusion". Review of Scientific Instruments. 74 (10): 4314–4323. Bibcode:2003RScI...74.4314T. doi:10.1063/1.1606534. ISSN 0034-6748.
39. ^ Hsu, S. C.; Awe, T. J.; Brockington, S.; Case, A.; Cassibry, J. T.; Kagan, G.; Messer, S. J.; Stanic, M.; Tang, X.; Welch, D. R.; Witherspoon, F. D. (2012). "Spherically Imploding Plasma Liners as a Standoff Driver for Magnetoinertial Fusion". IEEE Transactions on Plasma Science. 40 (5): 1287–1298. Bibcode:2012ITPS...40.1287H. doi:10.1109/TPS.2012.2186829. ISSN 1939-9375. S2CID 32998378.
40. ^ a b Clynes, Tom (2020). "5 Big ideas for fusion power: Startups, universities, and major companies are vying to commercialize a nuclear fusion reactor". IEEE Spectrum. 57 (2): 30–37. doi:10.1109/MSPEC.2020.8976899. ISSN 0018-9235. S2CID 211059641.
41. ^
42. ^ Nagamine, K (2007). Introductory muon science. Cambridge: Cambridge University Press. ISBN 978-0-521-03820-1. OCLC 124025585.
43. ^ "Plasma Physics". Government Reports Announcements. 72: 194. 1972.
44. ^ Miley, George H. (2013). Inertial electrostatic confinement (IEC) fusion : fundamentals and applications. Murali, S. Krupakar. Dordrecht: Springer. ISBN 978-1-4614-9338-9. OCLC 878605320.
45. ^ Kunkel, W.B. (1981). "Neutral-beam injection". In Teller, E. (ed.). Fusion. Lawrence Livermore National Laboratory. ISBN 9780126852417.
46. ^ Erckmann, V; Gasparino, U (December 1, 1994). "Electron cyclotron resonance heating and current drive in toroidal fusion plasmas". Plasma Physics and Controlled Fusion. 36 (12): 1869–1962. Bibcode:1994PPCF...36.1869E. doi:10.1088/0741-3335/36/12/001. ISSN 0741-3335.
47. ^ Ono, Y.; Tanabe, H.; Yamada, T.; Gi, K.; Watanabe, T.; Ii, T.; Gryaznevich, M.; Scannell, R.; Conway, N.; Crowley, B.; Michael, C. (May 1, 2015). "High power heating of magnetic reconnection in merging tokamak experiments". Physics of Plasmas. 22 (5): 055708. Bibcode:2015PhPl...22e5708O. doi:10.1063/1.4920944. hdl:1885/28549. ISSN 1070-664X.
48. ^ Yamada, M.; Chen, L.-J.; Yoo, J.; Wang, S.; Fox, W.; Jara-Almonte, J.; Ji, H.; Daughton, W.; Le, A.; Burch, J.; Giles, B. (December 6, 2018). "The two-fluid dynamics and energetics of the asymmetric magnetic reconnection in laboratory and space plasmas". Nature Communications. 9 (1): 5223. Bibcode:2018NatCo...9.5223Y. doi:10.1038/s41467-018-07680-2. ISSN 2041-1723. PMC 6283883. PMID 30523290.
49. ^ McGuire, Thomas. Heating Plasma for Fusion Power Using Magnetic Field Oscillations. Baker Botts LLP, assignee. Issued: 4/2/14, Patent 14/243,447. N.d. Print.
50. ^ "Towards a fusion reactor", Nuclear Fusion, IOP Publishing Ltd, 2002, doi:10.1887/0750307056/b888c9, ISBN 0750307056, retrieved 2021-12-12
51. ^ Pearson, Richard J; Takeda, Shutaro (2020), "Review of approaches to fusion energy", Commercialising Fusion Energy, IOP Publishing, doi:10.1088/978-0-7503-2719-0ch2, ISBN 978-0-7503-2719-0, S2CID 234561187, retrieved 2021-12-12
52. ^ Labik, George; Brown, Tom; Johnson, Dave; Pomphrey, Neil; Stratton, Brentley; Viola, Michael; Zarnstorff, Michael; Duco, Mike; Edwards, John; Cole, Mike; Lazarus, Ed (2007). "National Compact Stellarator Experiment Vacuum Vessel External Flux Loops Design and Installation". 2007 IEEE 22nd Symposium on Fusion Engineering: 1–3. doi:10.1109/FUSION.2007.4337935. ISBN 978-1-4244-1193-1. S2CID 9298179.
53. ^ Park, Jaeyoung; Krall, Nicholas A.; Sieck, Paul E.; Offermann, Dustin T.; Skillicorn, Michael; Sanchez, Andrew; Davis, Kevin; Alderson, Eric; Lapenta, Giovanni (June 1, 2014). "High Energy Electron Confinement in a Magnetic Cusp Configuration". Physical Review X. 5 (2): 021024. arXiv:1406.0133. Bibcode:2015PhRvX...5b1024P. doi:10.1103/PhysRevX.5.021024. S2CID 118478508.
54. ^ Mott-Smith, H. M.; Langmuir, Irving (September 1, 1926). "The Theory of Collectors in Gaseous Discharges". Physical Review. American Physical Society (APS). 28 (4): 727–763. Bibcode:1926PhRv...28..727M. doi:10.1103/physrev.28.727. ISSN 0031-899X.
55. ^ Esarey, Eric; Ride, Sally K.; Sprangle, Phillip (September 1, 1993). "Nonlinear Thomson scattering of intense laser pulses from beams and plasmas". Physical Review E. American Physical Society (APS). 48 (4): 3003–3021. Bibcode:1993PhRvE..48.3003E. doi:10.1103/physreve.48.3003. ISSN 1063-651X. PMID 9960936.
56. ^ Kantor, M Yu; Donné, A J H; Jaspers, R; van der Meiden, H J (February 26, 2009). "Thomson scattering system on the TEXTOR tokamak using a multi-pass laser beam configuration". Plasma Physics and Controlled Fusion. 51 (5): 055002. Bibcode:2009PPCF...51e5002K. doi:10.1088/0741-3335/51/5/055002. ISSN 0741-3335.
57. ^ Tsoulfanidis, Nicholas (1995). Measurement and detection of radiation. Library Genesis. Washington, DC : Taylor & Francis. ISBN 978-1-56032-317-4.
58. ^ Knoll, Glenn F. (2010). Radiation detection and measurement (4th ed.). Hoboken, NJ: John Wiley. ISBN 978-0-470-13148-0. OCLC 612350364.
59. ^ Larmor, Joseph (January 1, 1897). "IX. A dynamical theory of the electric and luminiferous medium.— Part III. relations with material media". Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character. 190: 205–300. Bibcode:1897RSPTA.190..205L. doi:10.1098/rsta.1897.0020.
60. ^ Stott PE, Gorini G, Prandoni P, Sindoni E, eds. (1998). Diagnostics for experimental thermonuclear fusion reactors 2. New York: Springer. ISBN 978-1-4615-5353-3. OCLC 828735433.
61. ^ Ishiyama, Shintaro; Muto, Yasushi; Kato, Yasuyoshi; Nishio, Satoshi; Hayashi, Takumi; Nomoto, Yasunobu (March 1, 2008). "Study of steam, helium and supercritical CO2 turbine power generations in prototype fusion power reactor". Progress in Nuclear Energy. Innovative Nuclear Energy Systems for Sustainable Development of the World. Proceedings of the Second COE-INES International Symposium, INES-2, November 26–30, 2006, Yokohama, Japan. 50 (2): 325–332. doi:10.1016/j.pnucene.2007.11.078. ISSN 0149-1970.
62. ^ T. Anklam; A. J. Simon; S. Powers; W. R. Meier (December 2, 2010). "LIFE: The Case for Early Commercialization of Fusion Energy" (PDF). Livermore, LLNL-JRNL-463536. Archived from the original (PDF) on 2015-09-04. Retrieved 2014-10-30.
63. ^ Hanaor, D.A.H.; Kolb, M.H.H.; Gan, Y.; Kamlah, M.; Knitter, R. (2014). "Solution based synthesis of mixed-phase materials in the Li2TiO3-Li4SiO4 system". Journal of Nuclear Materials. 456: 151–161. arXiv:1410.7128. Bibcode:2015JNuM..456..151H. doi:10.1016/j.jnucmat.2014.09.028. S2CID 94426898.
64. ^ Barr, William L.; Moir, Ralph W. (January 1, 1983). "Test Results on Plasma Direct Converters". Nuclear Technology - Fusion. 3 (1): 98–111. doi:10.13182/FST83-A20820. ISSN 0272-3921.
65. ^ Booth, William (October 9, 1987). "Fusion's $372-Million Mothball". Science. 238 (4824): 152–155. Bibcode:1987Sci...238..152B. doi:10.1126/science.238.4824.152. PMID 17800453. 66. ^ GRAD, HAROLD (2016). Containment in cusped plasma systems (classic reprint). Place of publication not identified: FORGOTTEN Books. ISBN 978-1-333-47703-5. OCLC 980257709. 67. ^ Lee, Chris (June 22, 2015). "Magnetic mirror holds promise for fusion". Ars Technica. Retrieved 2020-10-11. 68. ^ a b Pfalzner, Susanne. (2006). An introduction to inertial confinement fusion. New York: Taylor & Francis/CRC Press. ISBN 1-4200-1184-7. OCLC 72564680. 69. ^ Thorson, Timothy A. (1996). Ion flow and fusion reactivity characterization of a spherically convergent ion focus. University of Wisconsin, Madison. 70. ^ Barnes, D. C.; Nebel, R. A. (July 1998). "Stable, thermal equilibrium, large-amplitude, spherical plasma oscillations in electrostatic confinement devices". Physics of Plasmas. 5 (7): 2498–2503. Bibcode:1998PhPl....5.2498B. doi:10.1063/1.872933. ISSN 1070-664X. 71. ^ Hedditch, John; Bowden-Reid, Richard; Khachan, Joe (October 2015). "Fusion in a magnetically-shielded-grid inertial electrostatic confinement device". Physics of Plasmas. 22 (10): 102705. arXiv:1510.01788. doi:10.1063/1.4933213. ISSN 1070-664X. 72. ^ Carr, M.; Khachan, J. (2013). "A biased probe analysis of potential well formation in an electron only, low beta Polywell magnetic field". Physics of Plasmas. 20 (5): 052504. Bibcode:2013PhPl...20e2504C. doi:10.1063/1.4804279. 73. ^ Sieckand, Paul; Volberg, Randall (2017). Fusion One Corporation (PDF). Fusion One Corporation. 74. ^ Atzeni, Stefano; Meyer-ter-Vehn, Jürgen (June 3, 2004). The Physics of Inertial Fusion: BeamPlasma Interaction, Hydrodynamics, Hot Dense Matter. OUP Oxford. pp. 12–13. ISBN 978-0-19-152405-9. 75. ^ Velarde, Guillermo; Martínez-Val, José María; Ronen, Yigal (1993). Nuclear fusion by inertial confinement: a comprehensive treatise. Boca Raton; Ann Arbor; London: CRC Press. ISBN 978-0-8493-6926-1. OCLC 468393053. 76. ^ Iiyoshi, A; H. Momota; O Motojima; et al. (October 1993). "Innovative Energy Production in Fusion Reactors". National Institute for Fusion Science NIFS: 2–3. Bibcode:1993iepf.rept.....I. Archived from the original on 2015-09-04. Retrieved 2012-02-14. 77. ^ "Nuclear Fusion : WNA - World Nuclear Association". www.world-nuclear.org. Retrieved 2020-10-11. 78. ^ Rolfe, A. C. (1999). "Remote Handling JET Experience" (PDF). Nuclear Energy. 38 (5): 6. ISSN 0140-4067. Retrieved 2012-04-10. 79. ^ Sawan, M.E; Zinkle, S.J; Sheffield, J (2002). "Impact of tritium removal and He-3 recycling on structure damage parameters in a D–D fusion system". Fusion Engineering and Design. 61–62: 561–567. doi:10.1016/s0920-3796(02)00104-7. ISSN 0920-3796. 80. ^ J. Kesner, D. Garnier, A. Hansen, M. Mauel, and L. Bromberg, Nucl Fusion 2004; 44, 193 81. ^ a b Nevins, W. M. (March 1, 1998). "A Review of Confinement Requirements for Advanced Fuels". Journal of Fusion Energy. 17 (1): 25–32. Bibcode:1998JFuE...17...25N. doi:10.1023/A:1022513215080. ISSN 1572-9591. S2CID 118229833. 82. ^ von Möllendorff, Ulrich; Goel, Balbir, eds. (1989). Emerging nuclear energy systems 1989: proceedings of the Fifth International Conference on Emerging Nuclear Energy Systems, Karlsruhe, F.R. Germany, July 3-6, 1989. Singapore: World Scientific. ISBN 981-02-0010-2. OCLC 20693180. 83. ^ Feldbacher, Rainer; Heindler, Manfred (1988). "Basic cross section data for aneutronic reactor". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 271 (1): 55–64. Bibcode:1988NIMPA.271...55F. doi:10.1016/0168-9002(88)91125-4. ISSN 0168-9002. 84. ^ "Nuclear Fusion: Laser-Beam Experiment Yields Exciting Results". LiveScience.com. October 8, 2013. 85. ^ "Record proton-boron fusion rate achieved - FuseNet". www.fusenet.eu. Archived from the original on 2014-12-02. Retrieved 2014-11-26. 86. Roberts, J. T. Adrian. (1981). Structural Materials in Nuclear Power Systems. Boston, MA: Springer US. ISBN 978-1-4684-7196-0. OCLC 853261260. 87. ^ "Roadmap highlights materials route to fusion". The Engineer. September 9, 2021. Retrieved 2021-09-17. 88. ^ Klueh, R.L. "Metals in the nuclear-fusion environment". Materials Engineering. 99: 39–42. 89. ^ Založnik, Anže (2016). Interaction of atomic hydrogen with materials used for plasma-facing wall in fusion devices: doctoral thesis (Thesis). Ljubljana: [A. Založnik]. OCLC 958140759. 90. ^ McCracken, G.M (1997). "Plasma surface interactions in controlled fusion devices". Nuclear Fusion. 37 (3): 427–429. doi:10.1088/0029-5515/37/3/413. ISSN 0029-5515. 91. ^ Mioduszewski, Peter (2000), "Hydrogen Recycling and Wall Equilibration In Fusion Devices", Hydrogen Recycling at Plasma Facing Materials, Dordrecht: Springer Netherlands, pp. 195–201, doi:10.1007/978-94-011-4331-8_23, ISBN 978-0-7923-6630-0, retrieved 2020-10-13 92. ^ a b c Nemanič, Vincenc (2019). "Hydrogen permeation barriers: Basic requirements, materials selection, deposition methods, and quality evaluation". Nuclear Materials and Energy. 19: 451–457. doi:10.1016/j.nme.2019.04.001. ISSN 2352-1791. 93. ^ Molodyk, A., et al. "Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion." Scientific reports 11.1 (2021): 1-11. 94. ^ a b "Thermal response of nanostructured tungsten"Shin Kajita, et al., January 2014, Nucl. Fusion 54 (2014) 033005 (10pp) 95. ^ a b c McCracken, Garry; Stott, Peter (June 8, 2012). Fusion: The Energy of the Universe. Academic Press. pp. 198–199. ISBN 978-0-12-384656-3. Retrieved 2012-08-18. 96. ^ Dulon, Krista (2012). "Who is afraid of ITER?". iter.org. Archived from the original on 2012-11-30. Retrieved 2012-08-18. 97. ^ Angelo, Joseph A. (November 30, 2004). Nuclear Technology. Greenwood Publishing Group. p. 474. ISBN 978-1-57356-336-9. Retrieved 2012-08-18. 98. ^ a b c Brunelli, B.; Knoepfel, Heinz, eds. (1990). Safety, environmental impact, and economic prospects of nuclear fusion. New York: Plenum Press. ISBN 978-1-4613-0619-1. OCLC 555791436. 99. ^ a b T. Hamacher; A.M. Bradshaw (October 2001). "Fusion as a Future Power Source: Recent Achievements and Prospects" (PDF). World Energy Council. Archived from the original (PDF) on 2004-05-06. 100. ^ 101. ^ Peterson, Tom. "Explain it in 60 seconds: Magnet Quench". Symmetry Magazine. Fermilab/SLAC. Retrieved 2013-02-15. 102. ^ Petrangeli, Gianni (January 1, 2006). Nuclear Safety. Butterworth-Heinemann. p. 430. ISBN 978-0-7506-6723-4. 103. ^ a b Claessens, Michel (October 17, 2019). ITER: the giant fusion reactor : bringing a sun to Earth. Cham. ISBN 978-3-030-27581-5. OCLC 1124925935. 104. ^ Harms, A. A.; Schoepf, Klaus F.; Kingdon, David Ross (2000). Principles of Fusion Energy: An Introduction to Fusion Energy for Students of Science and Engineering. World Scientific. ISBN 978-981-238-033-3. 105. ^ Carayannis, Elias G.; Draper, John; Iftimie, Ion A. (2020). "Nuclear Fusion Diffusion: Theory, Policy, Practice, and Politics Perspectives". IEEE Transactions on Engineering Management: 1–15. doi:10.1109/TEM.2020.2982101. ISSN 1558-0040. S2CID 219001461. 106. ^ Markandya, Anil; Wilkinson, Paul (2007). "Electricity generation and health". The Lancet. 370 (9591): 979–990. doi:10.1016/S0140-6736(07)61253-7. PMID 17876910. S2CID 25504602. Retrieved 2018-02-21. 107. ^ Nicholas, T. E. G.; Davis, T. P.; Federici, F.; Leland, J.; Patel, B. S.; Vincent, C.; Ward, S. H. (February 1, 2021). "Re-examining the role of nuclear fusion in a renewables-based energy mix". Energy Policy. 149: 112043. arXiv:2101.05727. doi:10.1016/j.enpol.2020.112043. ISSN 0301-4215. S2CID 230570595. 108. ^ Cheng, E.T.; Muroga, Takeo (2001). "Reuse of Vanadium Alloys in Power Reactors". Fusion Technology. 39 (2P2): 981–985. doi:10.13182/fst01-a11963369. ISSN 0748-1896. S2CID 124455585. 109. ^ Streckert, H. H.; Schultz, K. R.; Sager, G. T.; Kantncr, R. D. (December 1, 1996). "Conceptual Design of Low Activation Target Chamber and Components for the National Ignition Facility". Fusion Technology. 30 (3P2A): 448–451. doi:10.13182/FST96-A11962981. ISSN 0748-1896. 110. ^ a b c d R. J. Goldston, A. Glaser, A. F. Ross: "Proliferation Risks of Fusion Energy: Clandestine Production, Covert Production, and Breakout";9th IAEA Technical Meeting on Fusion Power Plant Safety (accessible at no cost, 2013) and Glaser, A.; Goldston, R. J. (2012). "Proliferation risks of magnetic fusion energy: Clandestine production, covert production and breakout". Nuclear Fusion. 52 (4). 043004. Bibcode:2012NucFu..52d3004G. doi:10.1088/0029-5515/52/4/043004. 111. ^ a b Englert, Matthias; Franceschini, Giorgio; Liebert, Wolfgang (2011). Strong Neutron Sources - How to cope with weapon material production capabilities of fusion and spallation neutron sources? (PDF). 7th INMM/Esarda Workshop, Aix-en-Provence. Archived from the original (PDF) on 2014-02-24. 112. ^ "Energy for Future Centuries" (PDF). Archived from the original (PDF) on 2011-07-27. Retrieved 2013-06-22. 113. ^ Eric Christian; et al. "Cosmicopia". NASA. Archived from the original on 2011-11-06. Retrieved 2009-03-20. 114. ^ Fusion For Energy. "Fusion For Energy - Bringing the power of the sun to earth". f4e.europa.eu. Archived from the original on 2019-11-29. Retrieved 2020-07-17. 115. ^ "ITER governing council pushes schedule back five years and trims budget". Physics Today. 2016. doi:10.1063/pt.5.029905. ISSN 1945-0699. 116. ^ "ITER disputes DOE's cost estimate of fusion project". Physics Today. 2018. doi:10.1063/PT.6.2.20180416a. 117. ^ "The Sixth Framework Programme in brief" (PDF). ec.europa.eu. Retrieved 2014-10-30. 118. ^ Margraf, Rachel. "A Brief History of U.S. Funding of Fusion Energy". Retrieved 2021-07-21. 119. ^ DOE/CF-0167 - Department of Energy FY 2021 Congressional Budget Request, Budget in Brief, February 2020. https://www.energy.gov/sites/default/files/2020/02/f72/doe-fy2021-budget-in-brief_0.pdf 120. ^ editor., Nuttall, William J. (December 22, 2020). Commercialising fusion energy : how small businesses are transforming big science. ISBN 978-0-7503-2717-6. OCLC 1230513895. {{cite book}}: |last= has generic name (help) 121. ^ Fusion Energy Sciences Advisory Committee (2021). Powering the Future: Fusion & Plasmas (PDF). Washington: Department of Energy Fusion Energy Sciences. pp. ii. 122. ^ Helman, Christopher. "Fueled By Billionaire Dollars, Nuclear Fusion Enters A New Age". Forbes. Retrieved 2022-01-14. 123. ^ a b c Windridge, Melanie. "The New Space Race Is Fusion Energy". Forbes. Retrieved 2020-10-10. 124. ^ Pearson, Richard J; Takeda, Shutaro (2020), "Review of approaches to fusion energy", Commercialising Fusion Energy, IOP Publishing, doi:10.1088/978-0-7503-2719-0ch2, ISBN 978-0-7503-2719-0, S2CID 234561187, retrieved 2021-12-13 125. ^ Pearson, Richard J; Nuttall, William J (2020), "Pioneers of commercial fusion", Commercialising Fusion Energy, IOP Publishing, doi:10.1088/978-0-7503-2719-0ch7, ISBN 978-0-7503-2719-0, S2CID 234528929, retrieved 2021-12-13 126. ^ a b Carayannis, Elias G.; Draper, John; Iftimie, Ion A. (2020). "Nuclear Fusion Diffusion: Theory, Policy, Practice, and Politics Perspectives". IEEE Transactions on Engineering Management: 1–15. doi:10.1109/TEM.2020.2982101. ISSN 0018-9391. S2CID 219001461. 127. ^ a b "White House Sets Sights on Commercial Fusion Energy". www.aip.org. Retrieved 2022-05-03. 128. ^ a b Sing Lee; Sor Heoh Saw. "Nuclear Fusion Energy-Mankind's Giant Step Forward" (PDF). HPlasmafocus.net. Retrieved 2014-10-30. 129. ^ Kessel, C. E.; Blanchard, J. P.; Davis, A.; El-Guebaly, L.; Ghoniem, N.; Humrickhouse, P. W.; Malang, S.; Merrill, B. J.; Morley, N. B.; Neilson, G. H.; Rensink, M. E. (September 1, 2015). "The Fusion Nuclear Science Facility, the Critical Step in the Pathway to Fusion Energy". Fusion Science and Technology. 68 (2): 225–236. doi:10.13182/FST14-953. ISSN 1536-1055. OSTI 1811772. S2CID 117842168. 130. ^ a b Menard, J.E.; Brown, T.; El-Guebaly, L.; Boyer, M.; Canik, J.; Colling, B.; Raman, R.; Wang, Z.; Zhai, Y.; Buxton, P.; Covele, B. (October 1, 2016). "Fusion nuclear science facilities and pilot plants based on the spherical tokamak". Nuclear Fusion. 56 (10): 106023. Bibcode:2016NucFu..56j6023M. doi:10.1088/0029-5515/56/10/106023. ISSN 0029-5515. 131. ^ Cardozo, N. J. Lopes (February 4, 2019). "Economic aspects of the deployment of fusion energy: the valley of death and the innovation cycle". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 377 (2141): 20170444. Bibcode:2019RSPTA.37770444C. doi:10.1098/rsta.2017.0444. ISSN 1364-503X. PMID 30967058. S2CID 106411210. 132. ^ Surrey, E. (February 4, 2019). "Engineering challenges for accelerated fusion demonstrators". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 377 (2141): 20170442. Bibcode:2019RSPTA.37770442S. doi:10.1098/rsta.2017.0442. ISSN 1364-503X. PMC 6365852. PMID 30967054. 133. ^ Banacloche, Santacruz; Gamarra, Ana R.; Lechon, Yolanda; Bustreo, Chiara (October 15, 2020). "Socioeconomic and environmental impacts of bringing the sun to earth: A sustainability analysis of a fusion power plant deployment". Energy. 209: 118460. doi:10.1016/j.energy.2020.118460. ISSN 0360-5442. S2CID 224952718. 134. ^ Koepke, M. E. (January 25, 2021). "Factors influencing the commercialization of inertial fusion energy". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 379 (2189): 20200020. Bibcode:2021RSPTA.37900020K. doi:10.1098/rsta.2020.0020. ISSN 1364-503X. PMC 7741007. PMID 33280558. 135. ^ Menard, J.E.; Bromberg, L.; Brown, T.; Burgess, T.; Dix, D.; El-Guebaly, L.; Gerrity, T.; Goldston, R.J.; Hawryluk, R.J.; Kastner, R.; Kessel, C. (October 1, 2011). "Prospects for pilot plants based on the tokamak, spherical tokamak and stellarator". Nuclear Fusion. 51 (10): 103014. Bibcode:2011NucFu..51j3014M. doi:10.1088/0029-5515/51/10/103014. ISSN 0029-5515. 136. ^ a b HIWATARI, Ryoji; GOTO, Takuya (March 19, 2019). "Assessment on Tokamak Fusion Power Plant to Contribute to Global Climate Stabilization in the Framework of Paris Agreement". Plasma and Fusion Research. 14: 1305047. Bibcode:2019PFR....1405047H. doi:10.1585/pfr.14.1305047. ISSN 1880-6821. 137. ^ National Academies of Sciences, Engineering, and Medicine (U.S.). Committee on a Strategic Plan for U.S. Burning Plasma Research. Final report of the Committee on a Strategic Plan for U.S. Burning Plasma Research. Washington, DC. ISBN 978-0-309-48744-3. OCLC 1104084761. 138. ^ A Community Plan for Fusion Energy and Discovery Plasma Sciences. Washington, DC: American Physical Society Division of Plasma Physics Community Planning Process. 2020. 139. ^ "US Plasma Science Strategic Planning Reaches Pivotal Phase". www.aip.org. April 7, 2020. Retrieved 2020-10-08. 140. ^ Asmundssom, Jon; Wade, Will. "Nuclear Fusion Could Rescue the Planet from Climate Catastrophe". Bloomberg. Retrieved 2020-09-21. 141. ^ Michaels, Daniel (February 6, 2020). "Fusion Startups Step In to Realize Decades-Old Clean Power Dream". The Wall Street Journal. ISSN 0099-9660. Retrieved 2020-10-08. 142. ^ a b c d Handley, Malcolm C.; Slesinski, Daniel; Hsu, Scott C. (July 10, 2021). "Potential Early Markets for Fusion Energy". Journal of Fusion Energy. 40 (2): 18. arXiv:2101.09150. doi:10.1007/s10894-021-00306-4. ISSN 0164-0313. S2CID 231693147. 143. ^ Ball, Philip (November 17, 2021). "The chase for fusion energy". Nature. 599 (7885): 352–366. doi:10.1038/d41586-021-03401-w. PMID 34789909. S2CID 244346561. 144. ^ "A Historic Decision: To Demonstrate Practical Fusion at Culham". General Fusion. June 16, 2021. Retrieved 2021-06-18. 145. ^ Holland, Andrew (July 15, 2021). "Congress Would Fund Fusion Cost-Share Program in Committee-Passed Appropriations Bill". Fusion Industry Assn. Retrieved 2021-07-16. 146. ^ Spangher, Lucas; Vitter, J. Scott; Umstattd, Ryan (2019). "Characterizing fusion market entry via an agent-based power plant fleet model". Energy Strategy Reviews. 26: 100404. doi:10.1016/j.esr.2019.100404. ISSN 2211-467X. 147. ^ "Global Energy Perspectives 2019". Energy Insights- Mckinsey.{{cite web}}: CS1 maint: url-status (link) 148. Nicholas, T. E. G.; Davis, T. P.; Federici, F.; Leland, J. E.; Patel, B. S.; Vincent, C.; Ward, S. H. (February 2021). "Re-examining the Role of Nuclear Fusion in a Renewables-Based Energy Mix". Energy Policy. 149: 112043. arXiv:2101.05727. doi:10.1016/j.enpol.2020.112043. S2CID 230570595. 149. ^ Entler, Slavomir; Horacek, Jan; Dlouhy, Tomas; Dostal, Vaclav (June 1, 2018). "Approximation of the economy of fusion energy". Energy. 152: 489–497. doi:10.1016/j.energy.2018.03.130. ISSN 0360-5442. 150. ^ "Levelized Cost of Energy and Levelized Cost of Storage 2019". Lazard.com. Retrieved 2021-06-01. 151. ^ Holland, Andrew (November 13, 2020). "Political and commercial prospects for inertial fusion energy". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 378 (2184): 20200008. Bibcode:2020RSPTA.37800008H. doi:10.1098/rsta.2020.0008. PMID 33040662. S2CID 222277887. 152. ^ a b "Safety in Fusion". www.iaea.org. May 28, 2021. Retrieved 2021-06-01. 153. ^ Slesinski, Daniel (January 28, 2021). "NRC Hosts Virtual Public Meeting on Developing Options for a Regulatory Framework for Fusion Energy". Fusion Industry Assn. Retrieved 2021-02-14. 154. ^ Slesinski, Daniel (March 30, 2021). "NRC Hosts Second Virtual Public Meeting on Developing a Regulatory Framework for Fusion Energy". Fusion Industry Assn. Retrieved 2021-04-10. 155. ^ Holland, Andrew (January 5, 2021). "Fusion Legislation Signed into Law". Fusion Industry Assn. Retrieved 2021-02-14. 156. ^ Windridge, Melanie. "U.K Serious About Fusion: New Report On Regulation Recommends Proportionate, Agile Approach". Forbes. Retrieved 2021-06-03. 157. ^ Holland, Andrew (June 1, 2021). "UK Regulatory Horizons Council Issues Report on Fusion Energy Regulation". Fusion Industry Assn. Retrieved 2021-06-21. 158. ^ Department for Business, Energy, & Industrial Strategy (2021). Towards Fusion Energy: The UK Government's Fusion Strategy (PDF). London: UK Government.{{cite book}}: CS1 maint: multiple names: authors list (link) 159. ^ "Government sets out vision for UK's rollout of commercial fusion energy". GOV.UK. Retrieved 2021-10-15. 160. ^ "UK government publishes fusion strategy - Nuclear Engineering International". www.neimagazine.com. Retrieved 2021-10-15. 161. ^ a b Holland, Andrew. "Fusion energy needs smart federal government regulation". The Washington Times. Retrieved 2020-10-10. 162. ^ Turrell, Arthur (August 28, 2021). "The race to give nuclear fusion a role in the climate emergency". the Guardian. Retrieved 2022-02-15. 163. ^ a b Clery, Daniel. (July 29, 2014). A piece of the sun : the quest for fusion energy. New York. ISBN 978-1-4683-1041-2. OCLC 1128270426. 164. ^ "Will China beat the world to nuclear fusion and clean energy?". BBC News. April 18, 2018. Retrieved 2020-10-12. 165. ^ a b Carayannis, Elias G.; Draper, John; Bhaneja, Balwant (October 2, 2020). "Towards Fusion Energy in the Industry 5.0 and Society 5.0 Context: Call for a Global Commission for Urgent Action on Fusion Energy". Journal of the Knowledge Economy. 12 (4): 1891–1904. doi:10.1007/s13132-020-00695-5. ISSN 1868-7873. S2CID 222109349. 166. ^ Carayannis, Elias G.; Draper, John (April 22, 2021). "The place of peace in the ITER machine assembly launch: Thematic analysis of the political speeches in the world's largest science diplomacy experiment". Peace and Conflict: Journal of Peace Psychology. 27 (4): 665–668. doi:10.1037/pac0000559. ISSN 1532-7949. S2CID 235552703. 167. ^ Gi, Keii; Sano, Fuminori; Akimoto, Keigo; Hiwatari, Ryoji; Tobita, Kenji (2020). "Potential contribution of fusion power generation to low-carbon development under the Paris Agreement and associated uncertainties". Energy Strategy Reviews. 27: 100432. doi:10.1016/j.esr.2019.100432. 168. ^ Nicholas, T.E.G.; Davis, T.P.; Federici, F.; Leland, J.; Patel, B.S.; Vincent, C.; Ward, S.H. (2021). "Re-examining the role of nuclear fusion in a renewables-based energy mix". Energy Policy. 149: 112043. arXiv:2101.05727. doi:10.1016/j.enpol.2020.112043. ISSN 0301-4215. S2CID 230570595. 169. ^ Carayannis, Elias; Draper, John; Crumpton, Charles (2022). "Reviewing fusion energy to address climate change by 2050". Journal of Energy and Development. 47 (1). 170. ^ "National Academies calls for a fusion pilot plant". Bulletin of the Atomic Scientists. April 14, 2021. Retrieved 2021-04-15. 171. ^ "US must make an infrastructure investment in fusion energy". Washington Examiner. July 13, 2021. Retrieved 2021-07-16. 172. ^ "An aggressive market-driven model for US fusion power development". MIT News | Massachusetts Institute of Technology. Retrieved 2021-02-26. 173. ^ Cho, Adrian (February 19, 2021). "Road map to U.S. fusion power plant comes into clearer focus—sort of". Science. Retrieved 2021-03-06. 174. ^ Kramer, David (March 10, 2021). "Academies urge public–private effort to build a pilot fusion-power plant". Physics Today. doi:10.1063/PT.6.2.20210310a. S2CID 243296520. 175. ^ aaleman19 (February 19, 2021). "FIA Congratulates Congressional Bipartisan Fusion Caucus". Fusion Industry Assn. Retrieved 2021-02-26. 176. ^ Vries, Gieljan de. "Expert panel approves next DEMO design phase". www.euro-fusion.org. Retrieved 2021-02-16. 177. ^ Robert F. Heeter; et al. "Conventional Fusion FAQ Section 2/11 (Energy) Part 2/5 (Environmental)". Fused.web.llnl.gov. Archived from the original on 2001-03-03. Retrieved 2014-10-30. 178. ^ Frank J. Stadermann. "Relative Abundances of Stable Isotopes". Laboratory for Space Sciences, Washington University in St. Louis. Archived from the original on 2011-07-20. 179. ^ J. Ongena; G. Van Oost. "Energy for Future Centuries" (PDF). Laboratorium voor Plasmafysica– Laboratoire de Physique des Plasmas Koninklijke Militaire School– École Royale Militaire; Laboratorium voor Natuurkunde, Universiteit Gent. pp. Section III.B. and Table VI. Archived from the original (PDF) on 2011-07-27. 180. ^ EPS Executive Committee. "The importance of European fusion energy research". The European Physical Society. Archived from the original on 2008-10-08. 181. ^ "Space propulsion | Have fusion, will travel". ITER. Retrieved 2021-06-21. 182. ^ Holland, Andrew (June 15, 2021). "Funding for Fusion for Space Propulsion". Fusion Industry Assn. Retrieved 2021-06-21. 183. ^ Schulze, Norman R; United States; National Aeronautics and Space Administration; Scientific and Technical Information Program (1991). Fusion energy for space missions in the 21st century. Washington, DC; Springfield, Va.: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program ; [For sale by the National Technical Information Service [distributor. OCLC 27134218. 184. ^ "Princiiples of Fusion Energy Utilization in Space Propulsion", Fusion Energy in Space Propulsion, Progress in Astronautics and Aeronautics, American Institute of Aeronautics and Astronautics, pp. 1–46, January 1, 1995, doi:10.2514/5.9781600866357.0001.0046, ISBN 978-1-56347-184-1, retrieved 2020-10-11 185. ^ Scharping, Nathaniel (March 23, 2016). "Why Nuclear Fusion Is Always 30 Years Away". Discover Magazine. Retrieved 2021-06-15.{{cite web}}: CS1 maint: url-status (link) 186. ^ Stix, T. H. (1998). "Highlights in early stellarator research at Princeton". Helical System Research. 187. ^ Johnson, John L. (November 16, 2001). The Evolution of Stellarator Theory at Princeton (Technical report). doi:10.2172/792587. OSTI 792587. 188. ^ Irvine, Maxwell (2014). Nuclear power: a very short introduction. Oxford: Oxford University Press. ISBN 978-0-19-958497-0. OCLC 920881367. 189. ^ Key, M.H. (1985). "Highlights of laser fusion related research by United Kingdom universities using the SERC Central Laser Facility at the Rutherford Appleton Laboratory". Nuclear Fusion. 25 (9): 1351–1353. doi:10.1088/0029-5515/25/9/063. 190. ^ Verlarde, G.; Carpintero–Santamaría, Natividad, eds. (2007). Inertial confinement nuclear fusion : a historical approach by its pioneers. London: Foxwell & Davies (UK). ISBN 978-1-905868-10-0. OCLC 153575814. 191. ^ Matthew McKinzie; Christopher E. Paine (2000). "When peer review fails : The Roots of the National Ignition Facility (NIF) Debacle". National Resources Defense Council. Retrieved 2014-10-30. 192. ^ Kusama, Y. (2002), Stott, Peter E.; Wootton, Alan; Gorini, Giuseppe; Sindoni, Elio (eds.), "Requirements for Diagnostics in Controlling Advanced Tokamak Modes", Advanced Diagnostics for Magnetic and Inertial Fusion, Boston, MA: Springer US, pp. 31–38, doi:10.1007/978-1-4419-8696-2_5, ISBN 978-1-4419-8696-2 193. ^ Menard, J. E. (February 4, 2019). "Compact steady-state tokamak performance dependence on magnet and core physics limits". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 377 (2141): 20170440. Bibcode:2019RSPTA.37770440M. doi:10.1098/rsta.2017.0440. ISSN 1364-503X. PMC 6365855. PMID 30967044. 194. ^ Kaw, P.K (1999). "Steady state operation of tokamaks". Nuclear Fusion. 39 (11): 1605–1607. doi:10.1088/0029-5515/39/11/411. ISSN 0029-5515. 195. ^ "Tore Supra". Archived from the original on 2012-11-15. Retrieved 2016-02-03. 196. ^ Smirnov, V.P. (December 30, 2009). "Tokamak foundation in USSR/Russia 1950–1990". Nuclear Fusion. 50 (1): 014003. doi:10.1088/0029-5515/50/1/014003. ISSN 0029-5515. 197. ^ Y-K Martin Peng, "Spherical Torus, Compact Fusion at Low Yield"., ORNL/FEDC-87/7 (December 1984) 198. ^ a b Sykes, Alan (1997). "High β produced by neutral beam injection in the START (Small Tight Aspect Ratio Tokamak) spherical tokamak". Physics of Plasmas. 4 (5): 1665–1671. Bibcode:1997PhPl....4.1665S. doi:10.1063/1.872271. ISSN 1070-664X. 199. ^ Braams, C. M.; Stott, P. E. (2002). Nuclear fusion: half a century of magnetic confinement fusion research. ISBN 978-0-367-80151-9. OCLC 1107880260. 200. ^ Jarvis, O. N (June 16, 2006). "Neutron measurements from the preliminary tritium experiment at JET (invited)". Review of Scientific Instruments. 63 (10): 4511–4516. doi:10.1063/1.1143707. 201. ^ Garin, Pascal (October 2001). "Actively cooled plasma facing components in Tore Supra". Fusion Engineering and Design. 56–57: 117–123. doi:10.1016/s0920-3796(01)00242-3. ISSN 0920-3796. 202. ^ 203. ^ Claessens, Michel (2020). ITER: The Giant Fusion Reactor. doi:10.1007/978-3-030-27581-5. ISBN 978-3-030-27580-8. S2CID 243590344. 204. ^ Atzeni, Stefano (2004). The physics of inertial fusion : beam plasma interaction, hydrodynamics, hot dense matter. Meyer-ter-Vehn, Jürgen. Oxford: Clarendon Press. ISBN 978-0-19-856264-1. OCLC 56645784. 205. ^ Pfalzner, Susanne (March 2, 2006). An Introduction to Inertial Confinement Fusion. CRC Press. doi:10.1201/9781420011845. ISBN 978-0-429-14815-6. 206. ^ "People's Daily Online -- China to build world's first "artificial sun" experimental device". en.people.cn. Retrieved 2020-10-10. 207. ^ What is NIF? Archived July 31, 2017, at the Wayback Machine, Lawrence Livermore National Laboratory. 208. ^ Kanellos, Michael. "Hollywood, Silicon Valley and Russia Join Forces on Nuclear Fusion". Forbes. Retrieved 2017-08-21. 209. ^ Frochtzwajg, Jonathan. "The secretive, billionaire-backed plans to harness fusion". BBC. Retrieved 2017-08-21. 210. ^ Clery, Daniel (July 25, 2014). "Fusion's restless pioneers". Science. 345 (6195): 370–375. Bibcode:2014Sci...345..370C. doi:10.1126/science.345.6195.370. ISSN 0036-8075. PMID 25061186. 211. ^ Gray, Richard. "The British reality TV star building a fusion reactor". Retrieved 2017-08-21. 212. ^ Clery, Daniel (April 28, 2017). "Private fusion machines aim to beat massive global effort". Science. 356 (6336): 360–361. Bibcode:2017Sci...356..360C. doi:10.1126/science.356.6336.360. ISSN 0036-8075. PMID 28450588. S2CID 206621512. 213. ^ SPIE Europe Ltd. "PW 2012: fusion laser on track for 2012 burn". Optics.org. Retrieved 2013-06-22. 214. ^ "Nuclear fusion milestone passed at US lab". BBC News. Retrieved 2014-10-30. 215. ^ "The Alectryon High Yield Neutron Generator". Phoenix Nuclear Labs. 2013. 216. ^ Chandler, David L. (August 10, 2015). "A small, modular, efficient fusion plant". MIT News. MIT News Office. 217. ^ Max Planck Institute for Experimental Physics (February 3, 2016). "Wendelstein 7-X fusion device produces its first hydrogen plasma". www.ipp.mpg.de. Retrieved 2021-06-15.{{cite web}}: CS1 maint: url-status (link) 218. ^ Wang, Brian (August 1, 2018). "Nuclear Fusion Updated project reviews". www.nextbigfuture.com. Retrieved 2018-08-03. 219. ^ MacDonald, Fiona. "The UK Just Switched on an Ambitious Fusion Reactor - And It Works". ScienceAlert. Retrieved 2019-07-03. 220. ^ "Italy's Eni defies sceptics, may up stake in nuclear fusion project". Reuters. April 13, 2018. 221. ^ "MIT Aims to Harness Fusion Power Within 15 years". April 3, 2018. 222. ^ "MIT Aims To Bring Nuclear Fusion To The Market In 10 Years". March 9, 2018. 223. ^ 224. ^ Molodyk, A.; Samoilenkov, S.; Markelov, A.; Degtyarenko, P.; Lee, S.; Petrykin, V.; Gaifullin, M.; Mankevich, A.; Vavilov, A.; Sorbom, B.; Cheng, J.; Garberg, S.; Kesler, L.; Hartwig, Z.; Gavrilkin, S.; Tsvetkov, A.; Okada, T.; Awaji, S.; Abraimov, D.; Francis, A.; Bradford, G.; Larbalestier, D.; Senatore, C.; Bonura, M.; Pantoja, A. E.; Wimbush, S. C.; Strickland, N. M.; Vasiliev, A. (January 22, 2021). "Development and large volume production of extremely high current density YBa 2 Cu 3 O 7 superconducting wires for fusion". Scientific Reports. 11 (1): 2084. doi:10.1038/s41598-021-81559-z. PMC 7822827. PMID 33483553. 225. ^ Clery, Daniel (April 8, 2021). "With 'smoke ring' technology, fusion startup marks steady progress". Science | AAAS. Retrieved 2021-04-11.{{cite web}}: CS1 maint: url-status (link) 226. ^ Morris, Ben (September 30, 2021). "Clean energy from the fastest moving objects on earth". BBC News. Retrieved 2021-12-09. 227. ^ "Session AR01: Review: Creating A Burning Plasma on the National Ignition Facility". 66 (13). {{cite journal}}: Cite journal requires |journal= (help) 228. ^ a b c d Wright, Katherine (November 30, 2021). "Ignition First in a Fusion Reaction". Physics. 14: 168. Bibcode:2021PhyOJ..14..168W. doi:10.1103/Physics.14.168. S2CID 244829710. 229. ^ 230. ^ 231. ^ Aut, Kramer David Author (December 3, 2021). "Lawrence Livermore's latest attempts at ignition fall short". Physics Today. 2021 (2): 1203a. doi:10.1063/PT.6.2.20211203a. S2CID 244935714. {{cite journal}}: |first1= has generic name (help) 232. ^ Conca, James. "Helion Energy Raises$500 Million On The Fusion Power Of Stars". Forbes. Retrieved 2021-12-19.
233. ^ Journal, Jennifer Hiller | Photographs by Tony Luong for The Wall Street (December 1, 2021). "WSJ News Exclusive | Nuclear-Fusion Startup Lands \$1.8 Billion as Investors Chase Star Power". Wall Street Journal. ISSN 0099-9660. Retrieved 2021-12-17.
234. ^ Blain, Loz (April 6, 2022). "Oxford spinoff demonstrates world-first hypersonic "projectile fusion"". New Atlas. Retrieved 2022-04-06.
235. ^ Lerner, Eric J.; S. Krupakar Murali; Derek Shannon; Aaron M. Blake; Fred Van Roessel (March 23, 2012). "Fusion reactions from >150 keV ions in a dense plasma focus plasmoid". Physics of Plasmas. 19 (3): 032704. Bibcode:2012PhPl...19c2704L. doi:10.1063/1.3694746. S2CID 120207711.
236. ^ Halper, Mark (March 28, 2012). "Fusion breakthrough". Smart PLanet. Retrieved 2012-04-01.
237. ^ a b "JET". Culham Centre Fusion Energy. Archived from the original on 2016-07-07. Retrieved 2016-06-26.
238. ^ "Fusion energy record demonstrates powerplant future". Culham Centre for Fusion Energy. February 7, 2022. Retrieved 2022-02-09.
239. ^
240. ^ "New record for fusion". MIT News | Massachusetts Institute of Technology. Retrieved 2020-10-11.
241. ^
242. ^ "Measuring Progress in Fusion Energy: The Triple Product". www.fusionenergybase.com. Archived from the original on 2020-10-01. Retrieved 2020-10-10.
243. ^ Cohen, Sam, and B. Berlinger. "Long-pulse Operation of the PFRC-2 Device." The Joint US-Japan Compact Torus. Wisconsin, Madison. 22 Aug. 2016. Lecture.
244. ^ "Successful second round of experiments with Wendelstein 7-X". www.ipp.mpg.de. Retrieved 2019-03-22.
245. ^ Lavars, Nick (November 26, 2018). "Wendelstein 7-X fusion reactor keeps its cool en route to record-breaking results". newatlas.com. Retrieved 2018-12-01.
246. ^ Magazine, Smithsonian; Gamillo, Elizabeth. "China's Artificial Sun Just Broke a Record for Longest Sustained Nuclear Fusion". Smithsonian Magazine.
247. ^
248. ^ Alan Sykes, "The Development of the Spherical Tokamak" Archived July 22, 2011, at the Wayback Machine, ICPP, Fukuoka September 2008
249. ^ Szondy, David (March 13, 2022). "Tokamak Energy achieves temperature threshold for commercial fusion". New Atlas. Retrieved 2022-03-15.
250. ^ Lavars, Nick (November 24, 2021). "KSTAR fusion reactor sets record with 30-second plasma confinement". New Atlas. Retrieved 2022-03-15.