Experiments on a reflex‐type sheet plasma negative‐ion source
ABSTRACT Negative hydrogen ions are extracted from a reflex‐type sheet plasma. Electron density and temperature profiles are measured with changing the filling gas pressure, and they are optimized to the H- production at the optimum gas pressure. The optimum gas pressure is 5 mTorr for the discharge current I d =2 A. As the discharge current I d increases, H- current increases linearly corresponding to the density increase in the center region, but saturates above I d =40 A. The maximum extracted H- current density of 4 mA/cm2 is obtained at I d =100 A.