Laser photo-detachment measurements in the ECR driven H-negative ion source PROMETHEUS I

Large interest is presently devoted to the development of high-power negative ion sources applicable to the International Thermonuclear Experimental Reactor (ITER) project. Hydrogen negative ions H^- are efficiently used to generate neutral beams for heating magnetically confined fusion plasmas [1]. Despite the large scale of ITER project, dedicated bench-scale experiments try to optimize the different sources acting on the elementary processes at the basis of the production of negative ions [2]. Understanding the negative ion formation mechanisms requires diagnostic techniques which can determine the absolute density of the hydrogen negative ions in the bulk plasma of these sources [3]. Photo-detachment is possibly the most convenient method towards this direction [3,4].