Double layer field shaping systems for toroidal plasmas

Claim 1

Apparatus for generation and confinement of a toroidal plasma of noncircular cross section having major and minor toroidal axes, with the plasma being elongated in the direction of the major toroidal axis, comprising means for providing a toroidal magnetic field for plasma confinement in a plasma confinement zone, means for providing a toroidal current in the plasma for generation of a poloidal magnetic field, a field shaping coil system for shaping the plasma cross section to stabilize the plasma and axisymmetrically with respect to the major toroidal axis to elongate the plasma in a direction along the major toroidal axis comprising an inner stabilizing coil system having a coil layer comprising a plurality of inner S coil elements aligned to conduct in a direction generally along the direction of the minor toroidal axis and disposed adjacent to and surrounding the plasma confinement zone with a physical contour generally corresponding to the desired elongated outer contour of the plasma, and an outer field shaping coil system having a coil layer comprising a plurality of outer coil elements aligned to conduct in a direction generally along the direction of the minor toroidal axis and being separated from the disposed exteriorly of the inner coil layer the electrical currents I S of said inner coil elements and the electrical currents I F of said outer coil elements being related in each of the coil elements as follows: ##EQU6## where I S j is the current in the jth S coil element, I F j is the current in the jth F coil element, I F j is the current in the jth F coil element for which all S coil electrical currents are zero, M SF ij is the mutual inductance between the ith S coil element and the jth F coil element, and M SS ij is the mutual inductance between the ith S coil element and the jth S coil element and, programming means for controlling the currents in the F coil elements of said outer coil layer to minimize the currents I S j in the S coil elements of the inner coil layer during plasma generation and confinement.