Effect of Argon Addition on H⁻ Ion Yield in Penning Discharge With Metal Hydride Cathode in Dc Regime

The influence of argon addition to the hydrogen plasma in a Penning discharge with a metal hydride cathode on H– ion generation is investigated experimentally. It was shown that argon addition weakly impacts on the H– ion yield in contrast to the previous results due to the localization of efficient H– production area within a narrow layer near the metal hydride cathode surface, so the rest of H– ions formed in the plasma volume largely ineffective in contributing to the extracted current. Experiments also showed slight expansion of the electron distribution function towards higher energies in case of argon injection along with the suppression of low-energy electrons.