No abstract

A previously developed three-term expansion method has been extended to study the electron swarm in argon in the energy range of the Ramsauer-Townsend minimum. The swarm parameters of electrons have been computed at temperatures of 89.6, 293 and 1000K in the range 1*10-21

The theoretical analysis of the energy distribution function of electrons in weakly ionised gases is developed in a relatively high E/N by using the three-term approximation of the distribution function in the Boltzmann equation. The continuity equation of the electron swarm with an anisotropic distribution function is also derived. The present analysis is applied to the steady-state electron swarm in neon: the energy distribution functions and the swarm parameters are computed numerically over a range of E/N from 141.3 to 1130 Td. Also the distribution functions are solved from the usual two-term Lorentz approximation. The range of the validity of the Lorentz approximation is investigated by the comparison between both results.

High-speed time-resolved Schlieren photographs are taken between impulse voltage application and breakdown in transformer oil using an image convertor camera at various applied voltages and framing speeds. Needle-to-plate electrodes are used and the oil is under vacuum. The pre-breakdown disturbance accompanied by shock waves emanates from the needle electrode for both polarities of the needle point. The disturbance from the negative point propagates step by step like a lightning discharge in air, while that from the positive point moves radially and reaches the plate electrode in one step. The pre-breakdown disturbance seems to be a gaseous phase which is generated in the liquid.

The authors describe a spectroscopic technique to investigate the transport processes of electrons and the quenching processes of excited metastable molecules under the condition of non-self-sustained Townsend discharges. The technique is applied to pure N2, and N2 including NO as an impurity at E/N=282.5 Td and currents less than 10-9 A. The quenching factor of N2(A3 Sigma u+) metastable by NO, defined by (1-(density of N2(A3 Sigma u+) in N2 with NO)/(density of N2(A3 Sigma u+) in pure N2)), is measured as a function of total gas density from the emission spectrum both of the second positive bands of N2 and of the gamma system of NO. The spatial profile of N2(A3 Sigma u+) is also monitored and estimated by the emission of the gamma system. It will be noted that half of the N2(A3 Sigma u+) metastables are deactivated with only 20 PPM of NO at N=1.94*1017 cm-3 in the low pressure ionisation growth chamber. The results give a quantitative explanation for the rapid decrease of the secondary ionisation coefficient in N2 in the presence of small amounts of the impurity. Also the radiative lifetime and the self-quenching rate coefficient are estimated in the present experimental conditions.