NEGATIVE HYDROGEN-IONS PRODUCED BY ELECTRON-TEMPERATURE CONTROL IN ANRF PLASMA

The formation of negative hydrogen ions is investigated in a pure hydr ogen RF plasma using a grid-method for electron temperature control. U sing the grid method we produce both high and low electron temperature plasmas in the separated regions in the chamber, in which the electro n temperature in the downstream region is controlled by the grid poten tial. The production rate of negative ions depends strongly on the gri d potential. We observe efficient negative hydrogen ion production in the downstream region when the grid is negatively biased in the hydrog en pressure range of 2-5 m Torr.