Fusion Science and Technology / Volume 4 / Number 2P2 / September 1983 / Pages 519-523
Plasma Engineering / dx.doi.org/10.13182/FST83-A22916
Methods of improving single particle confinement in the vacuum magnetic field of an ELMO Bumpy Torus (EBT) reactor have heretofore focused on enhancement of the effective magnetic aspect ratio through the addition of relatively low current supplementary coils to the basic EBT configuration of toroidally linked circular mirror coils. This method of aspect ratio enhancement is reviewed and compared to the use of noncircular, D-shaped mirror coils. A critical parameter in this evaluation is the required radial thickness δ of the blanket-shield assembly in the coil throat. Results indicate that D-coils represent an attractive alternative to the supplementary coil configurations if future neutronics calculations show that δ 1.1–1.2 m gives adequate neutron shielding and acceptable minimal breeding ratio under the coils. D-coils are shown to be extremely effective in symmetrizing mod-B in the midplane, thereby giving good trapped particle confinement, hot electron ring centering, and reactor volume utilization. In addition, magnetics systems with D-coils are significantly less complicated, with easier assembly, maintenance, and access, than configurations in which there are two supplementary coils per sector.