The effect of the addition of noble gases on H- production in a dc filament discharge in hydrogen

The effect of the addition of helium, neon, argon and xenon on the production of negative hydrogen ions in a magnetically confined de filament discharge has been investigated. The addition of helium and neon produces effects not significantly different from an equivalent increase in the hydrogen pressure. The addition of argon and low fractions of xenon produces significant increases in the negative-ion density for hydrogen pressures close to 1 mTorr. The addition of argon and xenon, by increasing the electron density and decreasing the electron temperature, achieves conditions closer to optimum for negative-ion production. The largest enhancement occurs with argon and it is suggested that a resonant energy exchange between excited argon atoms and hydrogen molecules is a contributing factor.