Characteristics of the RE Negative Ion Source Using a Mesh Grid Bias Method

Using a mesh 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. Both high and low electron temperature T, 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. It is also confirmed that grid bias method is more effective than the so-called magnetic filter method to optimize plasma parameters for H- production. Production of deuterium negative ions D- is also studied briefly.