Characterization of negative ion beam extracted from a negative ion source with a particle-in-cell model

Production of a high negative ion current requires the use of cesium in devices used for fusion applications and heavy ion accelerators. The cesium can be desposited in the entire surface of ion source as in Neutral Beam Injection (NBI) system for the ITER fusion reactor¹, or deposited only on the grid surface in the accelerator applications². The role of the cesium is to reduce the surface work function on the grid allowing an increase of negative ions production under heavy species surface impacts.