Surface production of H− ions by hyperthermal hydrogen atoms

Hyperthermal atomic hydrogen of energy in the range of 1–10 eV has been produced by electron impact dissociation in a cw 2.45 GHz microwave electron cyclotron resonance (ECR) discharge using a Lisitano-Coil. The flux and the energy of the hydrogen atoms have been measured by negative surface ionization of the atoms backscattered from pure and cesiated metal surfaces. A hyperthermal atomic hydrogen flux density equivalent to more than 0.5 A/cm2 and a temperature of about 5 eV has been produced for 420 W discharge power under cw condition. These hydrogen atoms can be directed onto an external converter located outside the discharge. This opens up new possibilities for H− ion source design.