MONTE-CARLO EVALUATION OF NEOCLASSICAL TRANSPORT IN TORSATRONS WITH DIFFERENT HELICAL WINDING LAWS

Neoclassical transport in realistic torsatron magnetic fields of reactor size is estimated by use of the Monte Carlo simulation technique. The configurations examined differ in the winding law which describes their helical conductors — a difference which has been predicted analytically to yield differing transport levels. This effect is confirmed not only in the 1/ν regime, for which the analytic calculations were originally done, but also at much lower collision frequencies. For the torsatrons examined, the overall transport rates differ by a factor of 1.5-3. It is noted that the configuration with the more favourable transport characteristics bears some similarity to an advanced stellarator. © 1990 IOP Publishing Ltd.