ENHANCEMENT OF H- VOLUME PRODUCTION IN DOUBLE PLASMA DISCHARGE

The production of hydrogen negative ions H- in a pure volume source ha s been studied. In our double plasma negative ion source, both energy and density of fast electrons are well controlled. Using this source, enhancement of H- production has been achieved. The extracted H- curre nt in the double plasma operation is higher than that in the single pl asma operation when observed under the same discharge power. Measureme nts of plasma parameters in the source and in the extractor regions ha ve been carried out for both cases. Enhancement of H- production is ac hieved by optimizing plasma parameters for a so-called two-step proces s of H- volume production.