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Trisops was an experimental machine for the study of magnetic confinement of plasmas with the ultimate goal of producing fusion power. The configuration was a variation of a compact toroid, a toroidal (doughnut-shaped) structure of plasma and magnetic fields with no coils penetrating the center. It lost funding in its original form in 1978.

The configuration was produced by combining two individual toroids produced by two conical θ pinch guns, located at either end of a length of Pyrex pipe with a constant magnetic guide field. The toroidal currents in the toroids were in opposite directions, so that they repelled each other. After coming to an equilibrium, they were adiabatically compressed by increasing the external field.

Force Free Plasma Vortices

Force free plasma vortices have uniform magnetic helicity and therefore are stable against many instabilities. Typically, the current decays faster in the colder regions until the gradient in helicity is large enough to allow a turbulent redistribution of the current.

Force free vortices follow the following equations.

\( \begin{align} \vec{\nabla} \times \vec{B} = \alpha\vec{B} \\ \vec{v} = \pm\beta\vec{B} \end{align} \)

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 spatial coordinates.

The magnetic flux surfaces are toroidal, with the current being totally toroidal at the core of the torus and totally poloidal at the surface of the torus. This is similar to the field configuration of a tokamak, except that the field-producing coils are simpler and do not penetrate the plasma torus.

Note that, unlike most plasma structures, the Lorentz force and the Magnus force, \( \rho\vec{\nabla} \times \vec{v} \), play equivalent roles. \( \rho \) is the mass density.
The Trisops Project

Dr. Daniel Wells, while working on the 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, Trisops, is an acronym for Thermonuclear Reactor In Support of Project Sherwood. He later moved to the University of Miami where he 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

The fourth and final version of the Trisops machine consisted of DC mirror coils producing a 0.5 T guide field, two conical θ-pinch guns which produced two counter-rotating plasma vortices inside a pyrex vacuum chamber. The vortices approached each other, collided, repelled each other, and finally came to rest. At that time the compression coils produced a 3.5 T field with a quarter-cycle rise time of 10 μs.

Results

The compressed rings retained their structure for 5 μs, with a density of 2 x 1017 cm−3, an ion temperature of 5 keV, an electron temperature of 300 eV. 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 μs. 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

Wells, D. R.; Davidson, J.; Phadke, L. G.; Hirschberg, J. G.; Ziajka, P. E.; Tunstall, J. (1978-07-17). "High-Temperature, High-Density Plasma Production by Vortex-Ring Compression". Physical Review Letters. American Physical Society (APS). 41 (3): 166–170. Bibcode:1978PhRvL..41..166W. doi:10.1103/physrevlett.41.166. ISSN 0031-9007.
CMTX Project, Nov. 1997

Fusion power, processes and devices
Core topics

Nuclear fusion
Timeline List of experiments Nuclear power Nuclear reactor Atomic nucleus Fusion energy gain factor Lawson criterion Magnetohydrodynamics Neutron Plasma

Processes,
methods
Confinement
type
Gravitational

Alpha process Triple-alpha process CNO cycle Fusor Helium flash Nova
remnants Proton-proton chain Carbon-burning Lithium burning Neon-burning Oxygen-burning Silicon-burning R-process S-process

Magnetic

Dense plasma focus Field-reversed configuration Levitated dipole Magnetic mirror
Bumpy torus Reversed field pinch Spheromak Stellarator Tokamak
Spherical Z-pinch

Inertial

Bubble (acoustic) Laser-driven Magnetized Liner Inertial Fusion

Electrostatic

Fusor Polywell

Other forms

Colliding beam Magnetized target Migma Muon-catalyzed Pyroelectric

Devices, experiments
Magnetic confinement
Tokamak
International

ITER DEMO PROTO

Americas

Canada STOR-M United States Alcator C-Mod ARC
SPARC DIII-D Electric Tokamak LTX NSTX
PLT TFTR Pegasus Brazil ETE Mexico Novillo [es]

Asia,
Oceania

China CFETR EAST
HT-7 SUNIST India ADITYA SST-1 Japan JT-60 QUEST [ja] Pakistan GLAST South Korea KSTAR

Europe

European Union JET Czech Republic COMPASS GOLEM [cs] France TFR WEST Germany ASDEX Upgrade TEXTOR Italy FTU IGNITOR Portugal ISTTOK Russia T-15 Switzerland TCV United Kingdom MAST-U START STEP

Stellarator
Americas

United States CNT CTH HIDRA HSX Model C NCSX Costa Rica SCR-1

Asia,
Oceania

Australia H-1NF Japan Heliotron J LHD

Europe

Germany WEGA Wendelstein 7-AS Wendelstein 7-X Spain TJ-II Ukraine Uragan-2M
Uragan-3M [uk]

RFP

Italy RFX United States MST

Magnetized target

Canada SPECTOR United States LINUS FRX-L – FRCHX Fusion Engine

Other

Russia GDT United States Astron LDX Lockheed Martin CFR MFTF
TMX Perhapsatron PFRC Riggatron SSPX United Kingdom Sceptre Trisops ZETA

Inertial confinement
Laser
Americas

United States Argus Cyclops Janus LIFE Long path NIF Nike Nova OMEGA Shiva

Asia

Japan GEKKO XII

Europe

European Union HiPER Czech Republic Asterix IV (PALS) France LMJ LULI2000 Russia ISKRA United Kingdom Vulcan

Non-laser

United States PACER Z machine

Applications

Thermonuclear weapon
Pure fusion weapon

International Fusion Materials Irradiation Facility ITER Neutral Beam Test Facility

Physics Encyclopedia

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