Development of negative ion beam accelerators for high power neutral beam systems

A 500 keV negative ion source for JT-60U and a 1 MeV ion source for ITER are being developed at JAERI. A beam acceleration test of the JT-60U negative ion source that is designed to produce a 500 keV, 22 A D beam for 10 s, has started. The ion source consists of a cesium seeded volume negative ion generator and a three-stage multi-aperture accelerator. Up to now, a D ion beam of 410 keV, 6.1 A, 0.2 s, 2.5 MW was accelerated. This is the world record of deuterium negative ion beam current and negative ion beam power. On the other hand, to demonstrate negative ion acceleration up to an energy of 1 MeV for ITER, we constructed a five-stage electrostatic accelerator and a 1 MV/1A test facility called “MeV Test Facility (MTF)”. The accelerator was conditioned up to a high voltage of 760 kV without beam. The H ion beam was successfully accelerated up to the energy of 700 keV with a drain current of 230 mA for 1 s