First Experiments with the Negative Ion Source NIO1

Neutral Beam Injectors (NBI) [typical injector MITICA (Megavolt ITer Injector Concept Advancement) specification are 1 MV 1280 beamlets total MV, beamlets, 55 Aof D- beam] , which need to be strongly optimized in the perspective of DEMO reactor, request a thorough understanding of the negative ion source used and of the multi-beamlet optics. A relatively compact RF ion source, named NIO1 (Negative Ion Optimization 1), with 9 beam apertures for a total H- current of 130 mA, 60kV acceleration voltage, was installed at Consorzio RFX, including a high voltage deck and a X-ray shield, to provide a test bench for source optimizations in the framework of the accompanying activities in support to the ITER NBI test facility. NIO1 operation has started in July 2014, at zero extraction voltage. Plasma is heated with a tunable 2 MHz (rf) radiofrequency. NIO1 status and plasma experiments both with air and with hydrogen as filling gas are described, up to a 1.7 kW rf power. Transition to inductively coupled plasma is reported in the case of air and briefly summarized for hydrogen.