Influence of different magnetic configurations on plasma parameters in SPIDER device

Abstract

The ITER fusion reactor will be heated by fast neutral beams generated by accelerating and neutralizing negative ions, produced in a RF inductively-coupled plasma which expands through a region featuring a magnetic filter. During the current shut down of the SPIDER device (until 2023) some modifications of the device have been planned to improve the system performance. These modifications are based on the experience gained during operation of SPIDER in previous years and include, among others, the addition of further sets of permanent magnets in the expansion chamber of the plasma source and around the RF drivers. The purpose of these modifications is to improve plasma confinement, and thus increase its density and homogeneity. The present paper reports the results of numerical studies of the plasma parameters in SPIDER source with different types of modifications of SPIDER device including new permanent magnets configurations. Analysis are done by means of the numerical code FSFS2D in which a self-consistent two-dimensional fluid description of the source is implemented. In order to partially account for the 3D flow pattern within our 2D model, simulations are run in two different layouts, in the vertical plane with the magnetic filter being perpendicular to the integration domain and in the horizontal plane with the filter field in the integration surface. Simulation results indicate, that the permanent magnets around the RF driver tends to increase the plasma density in the driver.