Stellarator pro and con

The recent cancellation of the National Compact Stellarator Experiment (NCSX; Physics Today, July 2008, page 25 ) calls to mind the fact that exactly 40 years ago the amazing Russian T-3 tokamak results burst upon the world and blindsided the US stellarator program. The ensuing shutdown of stellarator work at the Princeton Plasma Physics Laboratory and the rapid adoption of tokamaks at PPPL and other US laboratories were arguably the most important episodes in the US magnetic fusion program.

Successively more powerful tokamaks with ever more impressive performance came on line. Nevertheless, new stellarator projects were eventually funded by the US Department of Energy (DOE) at fusion labs in Tennessee, Wisconsin, and elsewhere, with at best lackluster results and usually far worse. As suggested by your article, stellarators are more complicated magnetic confinement devices than tokamaks, and thereby have always appealed to theoreticians who possess complicated minds and access to supercomputers, but nature is indifferent to both.

Having learned nothing from decades of tokamak progress and continued stellarator debacles, in the mid-1990s the directorate at PPPL and its counterpart at DOE reversed the 1968–69 revolution: They decided to shut down the flagship US tokamak fusion test reactor and replace it with a stellarator of unimaginable complexity, the recently aborted NCSX. Those foolish decisions have served only to expedite the ongoing demise of the US magnetic fusion program. Now, with the well-deserved termination of the NCSX project, perhaps limited resources can be refocused on the tokamak family as the only proven approach to magnetic fusion energy.