Speaker
Description
A negative ion beam source of 200 keV / 0.5 A has been under development at National Fusion Research Institute (NFRI). Recently, a Cs dispenser was equipped to feed the Cs to enhance the source performance. To see the Cs seeding effect, preliminary short-pulse beam extraction experiments were carried out with 50 keV accelerator prior to the installation of 200 keV accelerator. It was confirmed that the performance of Cs dispenser was maintained for more than 2 hours and the beam currents were increased by about 2 times. The co-extracted electron currents were drastically decreased. It is necessary to find optimum operational conditions such as the current waveform of Cs dispenser to control the Cs feeding rate and particularly the plasma grid (PG) temperature which is the main factor for the deposition rate or the thickness of Cs on the PG surface.
