Abstract
The production of hydrogen negative ions H- in a pure volume source has 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- current in the double plasma operation is higher than that in the single plasma operation when observed under the same discharge power. Measurements of plasma parameters in the source and in the extractor regions have been carried out for both cases. Enhancement of H- production is achieved by optimizing plasma parameters for a so-called two-step process of H- volume production.
