Beam calorimetry at the large negative ion source test facility ELISE: Experimental setup and latest results

Highlights: • ELISE is the first step in the European roadmap for the development of the ITER NBI. • Several beam diagnostic tools have been installed, the latest results are presented. • A gaussian fit procedure has been implemented to characterize the large ion beam. • Average beamlet group inhomogeneity is maximum 13%, close to the ITER target of 10%. • Beam divergence measured by calorimeter agrees with the BES measurements within 30%. - Abstract: The test facility ELISE is the first step within the European roadmap for the development of the ITER NBI system. ELISE is equipped with a 1 × 0.9 m² radio frequency negative ion source (half the ITER source size) and an ITER-like 3-grid extraction system which can extract an H⁻ or D⁻ beam for 10 s every 3 min (limited by available power supplies) with a total acceleration voltage of up to 60 kV. In the beam line of ELISE several beam diagnostic tools have been installed with the aim to evaluate beam intensity, divergence and uniformity. A copper diagnostic calorimeter gives the possibility to measure the beam power density profile with high resolution. The measurements are performed by an IR micro-bolometer camera and 48 thermocouples embedded in the calorimeter. A gaussian fit procedure has been implemented in order to characterize the large negative ion beam produced by ELISE. The latest results obtained from the beam calorimetry at ELISE show that the average beamlet group inhomogeneity is maximum 13%. The measured beam divergence agrees with the one measured by beam emission spectroscopy within 30%.