The Role of the Field Emission Effect in the Breakdown Mechanism of Direct‐Current Helium Discharges in Micrometer Gaps

Abstract

This paper contains results of experimental studies of the direct current breakdown voltage curves and voltampere characteristics of discharges generated in a system consisting of two plane-parallel tungsten and molybdenum electrodes at separations from 100 μm to 1 μm. The measurements were performed in the pressure range from 22.5 Torr to 738 Torr. The results are presented in the form of Paschen curves. Based on the measured breakdown voltage curves, the effective yields have been estimated in the case of different cathode materials. Differences between them are attributed to the influence of the work function of the cathode material on the current-voltage characteristics due to field emission effect in small gaps and high pressures. At low-pressures, however, vaporation of impurities from the electrodes material becomes significant. The present paper delivers new data on DC breakdown under these experimental conditions and conditions on the validity of the Paschen law in helium and provides better insight into the role of the field emission and the electrode materials on the breakdown voltage.

Extended scaling and Paschen law for micro-sized radiofrequency plasma breakdown

“…There has been considerable research on the gas breakdown mechanism and validity of the Paschen law for a wide range of driving frequencies [11][12][13][14] and gap distances [15,16]. Such fundamental research is essential because understanding of the breakdown process at different conditions is useful not only for development of efficient plasma source devices but also for controlling the plasma parameters in individual applications.…”

Analysis of gas discharge characteristics across micro-gap under different pressures

“…They attributed the deviation of the breakdown voltage curve under micro-gap from the traditional Paschen curve to the field emission which was caused by the strong field strength. 18) Semnani et al realized the quantification of each discharge mechanism in the discharge process by numerical simulation under different gas environments. They estimated the contribution ratio of the three discharge mechanisms to the prebreakdown current and concluded that the gas discharge breakdown under small electrode gaps was dominated by field emission.…”