Production ofHe+Ions by Mutual Collisions between Metastable Helium Atoms

The time dependence of the ${\mathrm{He}}^{+}$ ion density has been studied during the decay period of plasmas produced in helium and helium containing 5 × ${10}^{-3\mathrm{}}$% neon. The results show that during the early afterglow period the time dependence of the ${\mathrm{He}}^{+}$ density is determined by the ${\mathrm{He}}^{+}$ loss processes, while during the late afterglow period this time dependence may be governed by ${\mathrm{He}}^{+}$ production due to mutual collisions between triplet metastable helium atoms. The experimental conditions for observing the influence of the ${\mathrm{He}}^{+}$ production process on its decay rate are discussed.