Low-Pressure Glow Discharge in a Xenon/Chlorine Mixture

The spatial, electrical, and optical characteristics of a transverse glow discharge and a volume discharge with a spherical anode and plane cathode in low-pressure Xe/Cl[sub 2] mixtures are studied. It is shown that the transverse glow discharge in mixtures with a low chlorine content occupies most of the interelectrode gap and exists in the form of strata. As the total pressure (P >= 300 Pa) and the partial chlorine pressure (P(Cl[sub 2]) >= 80 Pa) increase, a solitary plasma domain with a volume of 1–2 cm[sup 3] forms in the discharge gap. It acts as a selective source of UV radiation in the XeCl(D–X) 236-nm, Cl[sub 2](D[sup ʹ]–A[sup ʹ]) 257-nm, and XeCl(B–X) 308-nm bands. In certain Xe/Cl[sub 2] mixtures, plasma selfoscillations in the frequency range 1–100 kHz are observed. The current of a low-pressure volume discharge with a spherical anode and plane cathode and the emission from it have both a dc and an ac component. The pressure and composition of the working mixture, as well as the average current of the volume discharge are optimized to attain the maximum emission intensity of the XeCl(D, B–X) bands. Low-pressure volume discharges in xenon/chlorine mixtures can be used as active media in low-pressure large-aperture planar or cylindrical excimer–halogen lamps emitting modulated or repetitive pulsed UV radiation.