Effect of metastable states on the evolution of a pulsed discharge in helium

The evolution of pulsed discharges in helium has been studied in a tube 0.2 m long and 0.3 m in diameter over the pressure range 0.1--1.0 torr and over the discharge-current range 0.05--0.40 A. The time evolution of the electron energy distribution, the electric field, and the density of metastable helium atoms has been found. The temperature dependence of the diffusion coefficient of metastable He atoms in the 23S state has been found. The shape of the discharge current pulse and that of the emission pulse depend on the pulse repetition frequency. This is attributed to the effect which the metastable helium atoms remaining after a pulse have on the evolution of the discharge in the following pulse