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 producti on of negative hydrogen ions in a magnetically confined de filament dischar ge has been investigated. The addition of helium and neon produces effects not significantly different from an equivalent increase in the hydrogen pre ssure. The addition of argon and low fractions of xenon produces significan t increases in the negative-ion density for hydrogen pressures close to 1 m Torr. The addition of argon and xenon, by increasing the electron density a nd decreasing the electron temperature, achieves conditions closer to optim um for negative-ion production. The largest enhancement occurs with argon a nd it is suggested that a resonant energy exchange between excited argon at oms and hydrogen molecules is a contributing factor.