Upgrade of accelerator of high current ion source for EAST neutral beam injector

A 4 MW high current ion source was developed for Experimental Advanced Superconducting Tokamak (EAST) neutral beam injector. In order to optimize the beam performance of high current ion source, the plasma grid of accelerator is replaced from circular cross section grid to diamond cross section grid. A new high current ion source with modified diamond plasma grid was designed and tested on the test bed. The results shows that, the mean arc efficiency is increased from 0.47 A/kW to 0.52 A/kW, and the divergence angle decreased from 1.8° to 1.4° with optimum beam perveance of 2.75 μperv and 2.3 μperv, respectively. The ion source with modified plasma grid can improve the performance of ion source effectively.