Contribution of atomic hydrogen flux on H~- ion beam extracted from a negative hydrogen ion source

摘要

A change in negative hydrogen (H~-) ion current extracted from a cesiated H~- ion source was observed by injecting an amplitude modulated hydrogen atomic beam. A 2.45 GHz microwave power excited hydrogen plasma for injecting atoms to the plasma grid of a multicusp H~- ion source. Under a cesium-free condition, the atom injection increased the extracted H~- ion current by nearly 50 %. The extracted H~- ion current reached 2.5 times the initial value when a small amount of cesium was introduced to the ion source. The microwave plasma injection to the cesiated ion source decreased the extracted H~- ion current by 13 %. The poor H~- ion production by the atom injection can be attributed to a low temperature of the hydrogen atoms produced by the microwave plasma source.