Controlling the characteristics of a repetitive volume discharge in CFC-12 and its mixtures with argon

Abstract

The parameters of a repetitive volume discharge in CF2Cl2 (CFC-12) and its mixtures with argon at pressures of P(CF2Cl2)≤0.4 kPa and P(Ar)≤1.2 kPa are studied. The discharge was ignited in an electrode system consisting of a spherical anode and a plane cathode by applying a dc voltage Uch≤1 kV to the anode. The electrical and optical characteristics of a volume discharge (such as the current-voltage characteristics; the plasma emission spectra; and the waveforms of the discharge voltage, the discharge current, and the total intensity of plasma emission) are investigated. It is found that, by shunting the discharge gap with a pulsed capacitor with a capacitance of C0≤3.5 nF, it is possible to control the amplitude and duration of the discharge current pulses, as well as the characteristics of the pulsed plasma emission. The increase in the capacitance C0 from 20 to 3500 pF leads to a significant increase in the amplitude and duration of the discharge current pulses, whereas the pulse repetition rate decreases from 70 to 3 kHz. The glow discharge exists in the form of a domain with a height of up to 3 cm and diameter of 0.5–3.0 cm. The results obtained can be used to design an untriggered repetitive germicidal lamp emitting in the Cl2(257/200 nm) and ArCl (175 nm) molecular bands and to develop plasmachemical methods for depositing amorphous fluorocarbon and chlorocarbon films.