A first characterization of NIO1 particle beam by means of a diagnostic calorimeter

Powerful neutral beam injectors (NBI) are required as heating and current drive systems for tokamaks like ITER. The developement of negative ion sources and accelerators (40A; 1MeV D - beam) in particular, is a crucial point and many issues still require a better understanding. In this framework, the experiment NIO1 (9 beamlets of 15 mA H- each, 60 kV) operated at Consorzio RFX has started operation in 2014 [1]. Both its RF negative ion source (up to 2.5kW) and its beamline are equipped with many diagnostics Error! Reference source not found.. For the early tests on the extraction system, oxygen has been used as well as hydrogen due to its higher electronegativity, which allows reaching currents large enough to test also the beam diagnostics even without caesium injection. In particular a 1D-CFC tile is used as a calorimeter to determine the beam power deposition by observing the rear surface of the tile with an IR camera; the same design is applied as for STRIKE [3], one of the diagnostics of SPIDER, the ITER-like ion source prototype [4], whose facility is currently under construction at Consorzio RFX. From this diagnostic it is possible to assess also the beam divergence and thus the beam optics. The present contribution describes the characterization of NIO1 particle beam by means of temperature and current measurements with different source and acceleration parameters.