EXPERIMENTS ON THE MULTIAMPERE NEGATIVE-ION SOURCE IN NATIONAL-INSTITUTE-FOR-FUSION-SCIENCE

The multiampere negative hydrogen ion source has been developed in National Institute for Fusion Science (NIFS). The ion source is a volume-production type multicusp one with an extraction area of 25 x 25 cm2. It is found that high density negative hydrogen ions of more than 1 x 10(12) cm-3 are produced in the center of the arc chamber with a double magnetic filter configuration. A supply of a small amount of cesium vapor into the arc chamber has greatly enhanced the H- ion current and reduced the operation pressure. The H- ion current of 3.3 A has been extracted from a Cs-seeded plasma at the pressure of 0.9 Pa.