Study of collisionless high-energy charged particle losses for stellarators in presence of resonant perturbations of the magnetic field

Using a numerical code based on guiding centre drift equations, collisionless high energy particle losses, and in particular alpha-particle losses, are studied for a number of stellarator configurations in the presence of magnetic islands caused by resonant perturbations of magnetic surfaces. Standard stellarator configurations, as well as an optimized quasi-helically symmetric stellarator, are used in this study. It is found that the role of islands in collisionless alpha-particle losses is practically negligible for standard stellarators, however, for optimized stellarators, islands can have a negative impact.