Monte Carlo studies of transport in stellarators

Transport is studied in toroidal geometry by integrating the guiding‐center equations in magnetic coordinates and simulating collisions with a Monte Carlo collision operator. The effects of the ambipolar electric field on diffusion losses are determined for model magnetic fields and the correct magnetic field of the Advanced Toroidal Facility (ATF‐1) stellarator. Comparisons are made of the computed diffusion coefficients and the theoretically predicted values.