Hydrogen negative ion beam acceleration in a multiaperture five-stage electrostatic accelerator

To develop a high power negative ion source/accelerator for 1 MeV class neu tral beam injector, hydrogen negative ion beam acceleration has been studie d using a five-stage, multiaperture electrostatic accelerator. After condit ioning each accelerator stage, the negative ions are accelerated to 1 MeV s uccessfully with a drain current of 25 mA for 1 s. Cs was introduced into t he ion source to produce higher current density. The highenst acceleration current density of 15 mA/cm(2) was successfully accelerated up to an energy of 700 keV for 1 s, keeping the optimum perveance. The total acceleration current of 200 mA was extracted from nine central apertures 14 mm diameter each. A preliminary measurement of the heat load in the accelerator showed that the direct interception of the beam for the first grid and the third g rid was negligibly small. The highest heat load was 4.5% of the input power at the second grid. (C) 2000 American Institute of Physics. [S0034-6748(00 )51102-2].