Calculations on the effect of supply frequency on the positive column of a low-pressure Hg-Ar AC discharge

Abstract

Results of a theoretical study of the positive column of a Hg-Ar discharge sustained by an AC current with a sinusoidal waveform (pAr=3 Torr, pHg=6×10−3 Torr, R=1·8 cm, Ieff=0·4-0·55 A) show a decrease in efficiency for UV emission with increasing supply frequency f for f<500 Hz, and an increase in efficiency for f>500 Hz. The efficiency can be slightly higher than the DC efficiency for a properly chosen frequency (fgreater, similar10 kHz). A comparison with experimental results, available in the literature for comparable discharges, is made, indicating a qualitative agreement. In addition, the temporal behaviour of a number of plasma quantities is presented for various supply frequencies.