Numerical studies on volume production of negative ions in hydrogen plasmas

In order to study the mechanism of H - production due to volume processes and the dependence of H - production on plasma parameters, a comprehensive model is presented. The model considers important processes for the production of both H - and positive ions. A set of particle balance equations in a steady-state hydrogen plasma are solved simultaneously. The calculated results have confirmed that H - ions are generated by dissociative attachment to highly vibrational excited hydrogen molecules (vibrational level nu "=5-10) and these molecules are produced by electrons with energies in excess of 30 eV.