Efficient negative ion production in rf plasmas using a mesh grid bias method.

Using a grid bias method for plasma parameter control, volume production of hydrogen negative ions H(-) is studied in pure hydrogen rf plasmas. Relationship between the extracted H(-) ion currents and plasma parameters is discussed. It is confirmed that both high and low electron temperature T(e) plasmas are produced in the separated regions when the grid is negatively biased. In addition, with changing grid potential V(g), values of n(e) increase while T(e) decrease in their values. The negative ion production depends strongly on the grid potential and related plasma conditions.