Patent Number: 042644135
Section: claims

1. In a method for producing and confining a toroidal plasma having a cross-section elongated in the direction of the major toroidal axis, comprising the steps of pulsing electrical current around the poloidal circumference of a plasma confinement zone and initially producing a sharp-boundaried, toroidal, theta-pinch plasma having plasma current flow substantially limited to a current sheath at the surface of the toroidal plasma to generate a toroidal magnetic field component which is substantially absent from the plasma interiorly of the current sheath whereby an electromagnetic confining force is exerted on the plasma from the plasma surface, and  subsequently relaxing said current sheath of the plasma while maintaining the plasma in a toroidal magnetic field to provide a toroidal diffuse-pinch plasma in which the plasma current is distributed over the cross-section of the plasma to generate a diffuse poloidal magnetic field component distributed throughout the plasma,  the improvement comprising the steps of  providing said diffuse-pinch plasma with a doublet or higher multiplet magnetic confinement configuration having one or more internal separatrices, and providing said initially formed, sharp-boundaried plasma with a current sheath having a contour corresponding to a flux surface of said doublet or higher multiplet diffuse pinch configuration.  means for producing a toroidal, sharp-boundaried theta-pinch plasma in a toroidal plasma confinement zone having a current sheath at the outside surface of the plasma, and  means for relaxing the current sheath of the sharp-boundaried plasma while maintaining a toroidal magnetic field in the plasma confinement zone to produce a toroidal diffuse-pinch plasma with a poloidal magnetic field distributed throughout the plasma, the improvement comprising  means for providing said diffuse plasma with a doublet or higher multiplet magnetic confinement configuration having one or more internal separatrices, and means for shaping the current sheath of said initially formed sharp-boundaried plasma to conform to a flux surface of said doublet or higher multiplet magnetic confinement configuration. 2. A method in accordance with claim 1 wherein said plasma is a plasma selected from the group consisting of hydrogen plasmas, deuterium plasmas, tritium plasmas, and mixtures thereof. 3. A method in accordance with claim 1 wherein the plasma has an elongation ratio of at least three, and wherein a higher multiplet magnetic confinement configuration is employed having more than two internal separatrices. 4. A method in accordance with claim 1 wherein said doublet or multiplet configuration is provided through the use of a toroidal conducting shell surrounding said plasma confinement zone and having a doublet or higher multiplet contour. 5. A method in accordance with claim 1 wherein said doublet or multiplet magnetic confinement configuration is provided at least in part by conducting current through field shaping coils oriented parallel to the minor toroidal axis to provide a magnetic field component which combines with the toroidal and poloidal plasma field components to provide a doublet or higher multiplet field. 6. In an apparatus for producing and maintaining a toroidal plasma having a cross-section elongated in the direction of the major toroidal axis, comprising, 7. Apparatus in accordance with claim 6 wherein said doublet or higher multiplet magnetic confinement means comprises a conducting shell having a doublet or higher multiplet flux surface contour, and wherein said current sheath shaping means comprises said conducting shell and means for pulsing electrical current around said shell. 8. Apparatus in accordance with claim 6 wherein said doublet or higher multiplet magnetic confinement means comprises magnetic field generating coils oriented parallel to the minor toroidal axis, and means for selectively energizing said coils to provide a magnetic field in said confinement zone having one or more internal separatrices. 9. Apparatus in accordance with claim 6 further comprising toroidal field generating coils encircling the minor toroidal axis and electrical current supply means for said coils to control the .beta. ratio of the confined plasma.