Non-resonant island divertor for stellarators

The shape parameters in the optimized Hamiltonian for field lines in nonresonant stellarator divertor control the magnetic topology. It is found that a nonresonant island divertor for stellarators can be designed with appropriate choice of these parameters. The field lines are lost to the walls in the magnetic turnstiles escaping through the holes in cantori. The probability function for the escape determines the scaling of full confinement time, the loss time, and the decay of confinement for field lines. These can be estimated by giving the field lines an artificial radial velocity. Results of our study of the nonresonant nonaxisymmetric island divertor for stellarator will be presented. Non-axisymmetric divertors have greater scope for control than axisymmetric divertors.