Drift island motion in helical plasma and its use for ash removal and high-energy ion injection

The 'drift island motion concept' is studied for a helical plasma for the purpose of ash removal and the injection of high-energy ions with large parallel velocity. The possibility of ash removal and the injection of the high energy ions in the helical device is shown. The control in time of the helical field amplitude and the magnetic field perturbations are used. Externally induced magnetic perturbations produced by the additional coil system for the 'island divertor', for example, are mentioned here. The island structures with n/m=1/1 and n/m=1/2 are used, where m and n are the 'wave' numbers of the magnetic perturbation. The variation of the helical field in time means that the magnetic configuration can be changed slowly during a plasma shot. (author)