PIC-MC code for the transport of plasma particles and surface produced negative ions across a magnetic field

摘要

For heating and current drive at ITER high power negative ion sources are required. The reference RF source is based on the tandem concept in which a hot plasma is generated and then cooled by means of a magnetic filter field. The complex interplay of the physical processes involved in the functionality of this filter is not fully understood yet. A 1d3v PIC-MC code is applied to the transport of charged particles across a magnetic filter using the actual plasma parameters. The electrons are magnetized and can not transverse the field directly. The plasma transport is mainly due to elastic collisions while inelastic collisions play an additional role for the reduction of the electron temperature. A positive shift of the potential is observed which slows down the protons and thus ensures quasi-neutrality. The plasma density is significantly decreased by the filter, having a strong influence on the space charge limited emission of surface produced negative ions.