Trisops
Encyclopedia
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.
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.
The first equation describes a Lorentz force
-free fluid: the
forces are everywhere zero. For a laboratory plasma α is a constant and β is a scalar function of spacial 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
,
,
play equivalent roles.
is the mass density.
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 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.
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 μsec.
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.
Magnetic confinement fusion
Magnetic confinement fusion is an approach to generating fusion power that uses magnetic fields to confine the hot fusion fuel in the form of a plasma. Magnetic confinement is one of two major branches of fusion energy research, the other being inertial confinement fusion. The magnetic approach is...
of plasmas
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
with the ultimate goal of producing fusion power
Fusion power
Fusion power is the power generated by nuclear fusion processes. In fusion reactions two light atomic nuclei fuse together to form a heavier nucleus . In doing so they release a comparatively large amount of energy arising from the binding energy due to the strong nuclear force which is manifested...
. The configuration was a variation of a compact toroid, a toroidal
Torus
In geometry, a torus is a surface of revolution generated by revolving a circle in three dimensional space about an axis coplanar with the circle...
(doughnut
Doughnut
A doughnut or donut is a fried dough food and is popular in many countries and prepared in various forms as a sweet snack that can be homemade or purchased in bakeries, supermarkets, food stalls, and franchised specialty outlets...
-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
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
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
Adiabatic process
In thermodynamics, an adiabatic process or an isocaloric process is a thermodynamic process in which the net heat transfer to or from the working fluid is zero. Such a process can occur if the container of the system has thermally-insulated walls or the process happens in an extremely short time,...
compressed by increasing the external field.
Force Free Plasma Vortices
Force free plasma vortices have uniform magnetic helicityMagnetic helicity
In plasma physics, magnetic helicity is the extent to which a magnetic field "wraps around itself". It is a generalization of the topological concept of linking number to the differential quantities required to describe the magnetic field...
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.
The first equation describes a Lorentz force
Lorentz force
In physics, the Lorentz force is the force on a point charge due to electromagnetic fields. It is given by the following equation in terms of the electric and magnetic fields:...
-free fluid: the
forces are everywhere zero. For a laboratory plasma α is a constant and β is a scalar function of spacial coordinates.The magnetic flux surfaces are toroidal, with the current being totally toroidal
Toroidal and poloidal
The earliest use of these terms cited by the Oxford English Dictionary is by Walter M. Elsasser in the context of the generation of the Earth's magnetic field by currents in the core, with "toroidal" being parallel to lines of latitude and "poloidal" being in the direction of the magnetic field...
at the core of the torus and totally poloidal
Toroidal and poloidal
The earliest use of these terms cited by the Oxford English Dictionary is by Walter M. Elsasser in the context of the generation of the Earth's magnetic field by currents in the core, with "toroidal" being parallel to lines of latitude and "poloidal" being in the direction of the magnetic field...
at the surface of the torus. This is similar to the field configuration of a tokamak
Tokamak
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...
, except that the field-producing coils are simpler and do not penetrate the plasma torus.
Note that, unlike most plasma structures, the Lorentz force
Lorentz force
In physics, the Lorentz force is the force on a point charge due to electromagnetic fields. It is given by the following equation in terms of the electric and magnetic fields:...
and the Magnus force
Magnus effect
The Magnus effect is the phenomenon whereby a spinning object flying in a fluid creates a whirlpool of fluid around itself, and experiences a force perpendicular to the line of motion...
,
,play equivalent roles.
is the mass density.The Trisops Project
Dr. Daniel Wells, while working on the StellaratorStellarator
A stellarator is a device used to confine a hot plasma with magnetic fields in order to sustain a controlled nuclear fusion reaction. It is one of the earliest controlled fusion devices, first invented by Lyman Spitzer in 1950 and built the next year at what later became the Princeton Plasma...
at the Princeton Plasma Physics Laboratory
Princeton Plasma Physics Laboratory
Princeton Plasma Physics Laboratory is a United States Department of Energy national laboratory for plasma physics and nuclear fusion science located on Princeton University's Forrestal Campus in Plainsboro Township, New Jersey. Its primary mission is research into and development of fusion as an...
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
Project Sherwood
Project Sherwood was the codename for a United States program in controlled nuclear fusion. It was funded under the Atoms for Peace initiative during the administration of President Dwight D. Eisenhower...
. He later moved to the University of Miami
University of Miami
The University of Miami is a private, non-sectarian university founded in 1925 with its main campus in Coral Gables, Florida, a medical campus in Miami city proper at Civic Center, and an oceanographic research facility on Virginia Key., the university currently enrolls 15,629 students in 12...
where he set set up the Trisops machine, supported by the National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
and Florida Power and Light.
The project continued until 1978 when the NSF discontinued the grant and the Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
did not pick up the support.
The Trisops Machine
The Trisops machine consisted of DC mirror coils producing a 0.5 TTesla (unit)
The tesla is the SI derived unit of magnetic field B . One tesla is equal to one weber per square meter, and it was defined in 1960 in honour of the inventor, physicist, and electrical engineer Nikola Tesla...
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 μsec.
Results
The compressed rings retained their structure for 5 μsec, 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 μsec.Followup
The project lost funding in 1978. The machine was disassembled and remained at the University of MiamiUniversity of Miami
The University of Miami is a private, non-sectarian university founded in 1925 with its main campus in Coral Gables, Florida, a medical campus in Miami city proper at Civic Center, and an oceanographic research facility on Virginia Key., the university currently enrolls 15,629 students in 12...
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.