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

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 1×0.9m2 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 10s every 3min (limited by available power supplies) with a total acceleration voltage of up to 60kV. 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%.