Effect of Penning ionisation on an electron swarm in Ar/Ne mixtures: Boltzmann equation analysis

The steady-state electron swarm parameters in Ar/Ne mixtures are analysed using a Boltzmann equation in which the influence of generation of secondary electrons through Penning ionisation in a discharge is taken properly into consideration. The ratios of the Townsend first ionisation coefficient to the electric field strength, alpha /E, calculated using the present equation for E/N values from 1.7 to 565 Td in neon with various admixtures of argon (ratio of the Ar to total concentrations from 10-6 to 10-1) agree well with the experimental values of Kruithof and Penning. It is found that generation of Penning electrons in an electron swarm lowers the mean electron energy appreciably, but influences the drift velocity very little. The values and shape of the effective excitation cross section of the metastable neon, which plays an important role in the determination of the amount of Penning electrons, are discussed.

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