Negative Helium Ions

Negative helium ions have been produced with an ion source previously used for negative hydrogen ion production. Positive helium ions pass through a charge-exchange tube filled with hydrogen gas and the resulting negative ions are magnetically analyzed. The momentum spectrum indicates peak yields of negative helium ions in excess of 3.5×${10}^{-9\mathrm{}}$ ampere under the conditions of this experiment. The yield of negative helium ions as a function of converter gas density suggests a possible mechanism for the creation of the negative helium ion.