First direct comparison of whole beam and single beamlet divergences in a negative ion source with simultaneous BES and CFC tile calorimetry measurements

Neutral beam injection (NBI) systems are required for heating and current drive in the next generation fusion experiment ITER, strict requirements placed on beamlet core divergence (<7 mrad) transmission into tokamak. The measurement of single is challenging due to multi-beamlet nature negative ion sources that such systems; diagnostic compatible with large high power beams can only provide spatially averaged measurements, leading mixing signals within results. To improve understanding this effect, a direct comparison has been made between by combination both Beam Emission Spectroscopy (BES) 1D carbon fiber composite tile calorimetry, joint campaign IPP Consorzio RFX. measurements performed so far at BATMAN Upgrade Test Facility have led two major First, an excellent agreement found divergences from diagnostics, showing results these be compared beamlets. Second, contribution deflection, caused alternating magnetic field extract grid, as measured using BES quantified up factor 3 increase when value. This demonstrates further investigation needed how information affects simulation experiment, which will step.