Some Physical Differences between Sheet Plasma and Multicusp Plasma as Volume Produced H- or D- Ion Sources

摘要

The H- ion volume production by means of a sheet plasma, the extracted H- ion current increases towards the outside across the magnetic field. This fact means that H- ions are produced outside of the sheet plasma, and is in contrast with the act that H- ions in the multicusp plasma are produced almost in the center region without magnetic field. Furthermore, in the optimum condition for extracting H- ions from the sheet plasma, the potential of the first extraction electrode is biased more negatively than that of the discharge anode or the plasma potential, while, in the optimum condition for the multicusp plasma, it is biased more positively. These physical differences between the two plasmas are related with confinement regions of electrons and ambipolar diffusions of plasma without magnetic field or across magnetic field.