A self-sustained volume discharge in vibrationally excited strongly electronegative gases

Abstract

This paper reports on the first experimental investigations into the physics of a self-sustained volume discharge (SSVD) in strongly electronegative gases on their vibrational excitation by irradiation of TEA CO2 laser. Examined are pure SF6, mixtures of SF6 with He, Ne and C2H6, and pure C2HCl3. In these gases, the discharge voltage and current oscillograms have been obtained for different delays between the laser and voltage applications, and on varying the laser fluences over a wide range. The observed effects of increasing the burning voltage and decreasing the discharge current in a CO2 laser-irradiated SSVD are treated in terms of enhanced electron attachment due to electron capture by vibrationally excited molecules of SF6 and C2HCl3. For the first time the effect of radically affecting a spatial electric current distribution over the discharge gap in strongly electronegative gases by irradiation of a specially profiled CO2 laser beam is found. Starting from this finding, the possibility of performing laser-controlled SSVD spatial structures in SF6 and SF6-based mixtures has been experimentally demonstrated. The problem of stability of a laser-irradiated SSVD in strongly electronegative gases is also touched upon.