Stability of bootstrap current driven magnetic islands in stellarators.

摘要

The stability of magnetic island producing perturbations due to fluctuations in the bootstrap current in stellarator configuration is examined. The stability criterion depends on the sign of the derivative of the rotational transform, the pressure gradient and the direction of the equilibrium bootstrap current which is determined by the structure of (parallel)B(parallel). It is found that quasi-helically symmetric stellarator configurations with p(prime)/(tau)(prime) < 0 are unstable to the formation of bootstrap current driven magnetic islands. The stability of conventional stellarator configurations depends upon the field structure.