Parametric study of the vacuum ultraviolet emission and electrical characteristics of a He–Xe microdischarge

Abstract

Vacuum ultraviolet emission and electrical characteristics of a simple discharge configuration consisting of two planar cylindrical electrodes operated with a dc voltage have been measured over a wide range of He/Xe mixtures and discharge pressures. Breakdown characteristics are consistent with those found in the literature, however current–voltage characteristics and the inferred discharge resistivity suggest the presence of a complex process controlling electron emission at the cathode. Ultraviolet vacuum emission maps of atomic and molecular xenon at 147, 150, and 173 nm, respectively, have been measured as a function of pressure, from 60 to 500 Torr, and gas mixture, from pure Xe to 5% Xe in He. The calibrated ratios of each emission map help to visualize the zones of strongest ultraviolet emission over a wide range of operating conditions. One-dimensional simulations of the breakdown voltage and current discharge have been performed using the commercially available discharge-modeling package SIGLO. Good agreement with experimental results is found in the case of pure helium and xenon, however, in the case of pure xenon, the gas temperature was adjusted (elevated) in order to reproduce the measured current–voltage characteristics. Modeling of the electron number density distribution indicates that the discharge is principally composed of a thick ion sheath near the cathode.

Mechanism for anomalously high voltages in high-pressure dc microdischarge mixtures of He, Ne, and Xe

“…A striking feature in the experiments is that the minimum in the discharge voltage is about the same for all mixed gas compositions studied, and equal to that measured for the pure Xe case. It is also clear that for scaled current densities above 10 -2 mA•cm -2 •Torr -2 the discharge voltages are higher than for pure xenon or pure helium, as we had seen previously 8,9 . We would expect the discharge voltage for He/Xe mixtures to be in between those of the pure Xe and pure He cases.…”

“…Our research aims at isolating these reactions from affects associated with complex geometries and/or non-steady fields by carrying out experiments in direct-current microdischarges of planar geometries. In recent papers 8,9 , we have presented results on the vacuum ultraviolet emission and the electrical characteristics of these planar dc microdischarges. We noted that for the range of current density studied (abnormal glow regime) the discharge voltages in mixtures of helium and xenon were surprisingly higher than in either pure xenon or pure helium, when the xenon fraction exceeded about 10%.…”

Plasma display panels: physics, recent developments and key issues

“…Increasing the xenon content leads to an increase of the VUV production efficiency, but also to an increase of the breakdown voltage [68]. Systematic and accurate measurements of the Paschen curves [69,70] under well controlled conditions (i.e. uniform electric field, well characterized MgO layer) in a wide range of rare gas, PDP mixtures, would be very useful and are still missing.…”

Modeling of microdischarge devices: Pyramidal structures

“…The height coordinate begins at the vertex of the MD cavity and is normalized by pressure (p o ϭ600 Torr). Contour labels have units of 10 13 cm Ϫ3 and the peak electron density is noted in each frame. pd scaling qualitatively holds based on similar morphology and peak density.…”

“…Early variants of MDs were constructed with the intent to operate as miniature hollow cathodes by reducing the cathode diameter while increasing the pressure to maintain the same pd as conventional low pressure hollow cathode devices. 10 Observations of optical emission spectra showed that when pd decreased into the 1-10 Torr cm range, the devices transitioned from operating similar to a Townsend discharge dominated by emission from neutral atoms to a mode resembling a hollow cathode discharge in which emission from high lying ion transitions was prominent. 1 Employing techniques developed for microelectronics and microelectromechanical systems fabrication, MD structures have been investigated.…”