Negative ion beam characterisation in BATMAN bymini-STRIKE: Improved design and newmeasurements

The ITER project requires additional heating provided by two injectors of neutral beams resulting from the neutralisation of accelerated negative ions. To study and optimise negative ion production, the SPIDER test facility (particle energy 100keV; beam current 50A) is under construction in Padova, with the aim of testing beam characteristics and to verify the source proper operation. The SPIDER beam will be characterised by the instrumented calorimeter STRIKE, whosemain components are one-directional carbon fibre carbon composite tiles. Some prototype tiles have been employed in 2012 as a small-scale version (mini-STRIKE) of the entire system to investigate the features of the beam from BATMAN at IPP-Garching. As the BATMAN beamlets are superposed at themeasurement position, about 1m from the grounded grid, an actively cooled coppermask is located in front of the tiles; holes in themask create an artificial beamlet structure. Recently themini-STRIKE has been updated, taking into account the results obtained in the first campaign. In particular the spatial resolution of the system has been improved by increasing the number of the coppermask holes. Moreover a custommeasurement system has been realized for the thermocouple signals and employed in BATMAN in view of its use in SPIDER. The present contribution gives a description of the new design of the system as well as of the thermocouplemeasurements system and its field test. A new series ofmeasurements has been carried out in BATMAN. The BATMAN beam characterisation in different experimental conditions is presented.