Compact torsatron reactors

Low-aspect-ratio torsatron configurations could lead to compact stellarator reactors with R0 = 8 to 11 m, roughly one-half to one-third the size of more conventional stellarator reactor designs. Minimum-sized torsatron reactors are found using various assumptions. Their size is relatively insensitive to the choice of the conductor parameters and depends mostly on geometrical constraints. The smallest size is obtained by eliminating the tritium breeding blanket under the helical winding on the inboard side and by reducing the radial depth of the superconducting coil. In this article engineering design issues and reactor performance are examined for three examples to illustrate the feasibility of this approach for compact torsatron reactors and for a medium-sized copper coil torsatron ignition experiment