User:Interguru/Trisops1

The Trisops project produces toroidal (doughnut-shaped) force-free stable plasma structures which confine a hot plasma with self-generated magnetic and velocity fields in order to sustain a controlled nuclear fusion reaction.

Unlike the Tokamak the confinement fields are self generated and do not require an elaborate confinement structure with magnetic coils.

The stable structures are produced with opposite rotation by two conical θ pinch guns, located at the ends of a TBD length of pipe. They are confined with a constant magnetic guide field . At the center of the apparatus, they collide, repelling each other, they stop where they are adiabaticly compressed by rapidly increasing the constant field.

Force Free Plasma Vortices

Force free plasma vortices are already in their lowest energy state. Having no free energy to drive instabilites, they are stable. The follow the following equations.

${\begin{aligned}{\vec {\nabla }}\times {\vec {B}}=\alpha {\vec {B}}\\{\vec {v}}=\pm \beta {\vec {B}}\end{aligned}}$ The first equation describes a lorentz force-free fluid: the ${\vec {j}}\times {\vec {B}}$ forces are everywhere zero. For a laboratory plasma α is a constant and β is a scalar function of spacial coordinates.

The structures are a torus, with the current being totally toroidal the core of the torus and totally poloidal at the surface of the torus. This is similar to the field configuration of a Tokomac, except there are no cumbersome massive external magnetic windings needed.

Note that, unlike most plasma structures, the lorentz force and the Magnus force , $\rho {\vec {\nabla }}\times {\vec {v}}$, play equal roles. $\rho$ is the mass density.

The Trisops Project

Dr. Daniel Wells, while working on Stellarator at the Princeton Plasma Physics Laboratory in the 1960s conceived of colliding and then compressing stable force free plasma toroids to produce conditions needed for thermonuclear fusion. The name, Trispos, is an acronym for Thermonuclear Reactor In Support of Project Sherwood. He later moved to the University of Miami where he set set up the Trisops machine, supported by the National Science Foundation and Florida Power and Light.

The project continued until 1978 when the NSF discontinued the grant and the Department of Energy did not pick up the support.

The Trisops Machine

Schematic diagram of Trisops machine used for creation and secondary compression of plasma vortex structures. Machine length is about 2m

The Trisops machine consists of DC mirror coils producing a 500G guide field, two conical θ-pinch guns which produced to contra-rotating plasma vortices inside a pyrex vacuum chamber. The vortices went towards each other. On collision, repelling each other, stood still. At this time the compression coils produced a 35kG field with a quarter-cycle rise time of 10 μsec.

Results

The compressed rings retained their structure for 5 μsec, with a density of 2 x 10¹⁷ cm^-3, an ion temperature of 5kev, an electron temperature of 300ev. A cutoff of funds prevented further measurements to resolve the discrepancy between the above figures, and the plasma electron-ion temperature equilibration time of 1 μsec.

Followup

The project lost funding in 1978. The machine was disassembled and remained at the University of Miami until 1997. At that time, the machine was moved to Lanham Md and reassembled for the CMTX project ( see reference ). The current status of the project and the machine are unknown.

References

• D. R. Wells, J. Davidson, L. G. Phadke, J. G. Hirschberg, P. E. Ziajka, and J. Tunstall "High-temperature, high-density plasma production by vortex-ring compression ". Phys. Rev. Lett. 41, 166 (1978).

• [http://www.rsiprinceton.com/pubs/APS%20DPP97.pdf CMTX Project, Nov. 1997