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It has been previously reported that the addition of argon to a hydrogen plasma in an RF driven ion source can substantially increase (up to a factor 4) the extracted and accelerated negative ion (H-) current). The Kamaboko III ion source operates at the pressure and plasma density close to those anticipated in the ion source proposed for the ITER neutral beam injectors. Measurements have been made of the plasma density; electron temperature and the negative ion yield as a function of the argon-seeding rate. The plasma parameters are determined with a fast spatially scanning Langmuir probe system. The effect on the H- yield is determined from the effect on the current extracted and accelerated from the source. Data will be presented for source filling pressures between 0.1 and 0.5 Pa of hydrogen and additions of argon from 0 to 30%, and a discharge power of 38 kW. All these data are collected in pure volume non-caesiated discharges. Some increase in the extracted H- yield is measured for small percentage additions of argon, (0�20%), but only at the highest H2 pressure used, 0.5 Pa.

Additional information

Authors: BOILSON D ET AL, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR)
Bibliographic Reference: An article published in: Fusion Engineering and Design, Volumes 66-68, September 2003, Pages 609-614 (22nd Symposium on Fusion Technology)
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