On physical processes in an ‘open’ discharge

Abstract

This paper reviews the key features of the ‘open’ photoelectric discharge (FED) used for the high-efficiency generation of electron beams (EBs) in medium-pressure gases and for subnanosecond switching of high-voltage pulses. The energy efficiency of EB generation in both FEDs and anomalous discharges is measured, and conditions for the predominance of photoemission are formulated. It is concluded that the FED is a long-known phenomenon and that the arguments put forward in Usp. Fiz. Nauk 188 1354 (2018) [Physics–Uspekhi 61 1234 (12) (2018)] against its existence are based on simplified discharge models and poorly performed experiments and make use of other authors' results of no direct relevance to the ‘open’ discharge.

Operating characteristics of open discharge-based plasma switches with helium, nitrogen and oxygen

“…It can be seen from the figure that in pure helium the IVC have a complex, non-monotonic N-shaped character (in the I(U) coordinates, curve 1), similar to those obtained earlier in [17]. An increase in voltage is initially accompanied by an increase in current.…”

“…The crosssection of the ionization of helium by fast helium atoms and ions is very small [25], and they do not cause appreciable ionization of the gas in the discharge gap. At voltage U ≈ 1.5 kV, corresponding to E/N ≈ 4 × 10 3 Td, the quantity and energy of runaway electrons becomes sufficient for electron beam formation [17], which causes generation by various mechanisms of VUV radiation of operating medium in the discharge gap and drift space [16], appearance of photocurrent and new increase of current.…”

“…In earlier works, high purity (99.999%) helium was used as the working medium. In [17] it was shown that molecular gases-oxygen O 2 and nitrogen N 2 , having high electron emission coefficient under the bombardment by fast molecules can also be used for electron beam generation in open discharge. The use of atmospheric gases O 2 and N 2 as a working medium, firstly, reduces the requirements for the technical and technology performance of kivotrons and reduces their cost.…”

Investigation of the characteristics and mechanism of subnanosecond switching of a new type of plasma switches. I. Devices with counter-propagating electron beams—kivotrons

“…To better understand the operation of the OD-based switches described below, we consider the difference between CVCs behavior for pure noble gases and contaminated gases, which were studied in [14] for OD and in [47] for AD. A part of these results is given below in addition to the studies presented in this paper.…”

“…Separately attainable parameters of pulses for such devices are as follows: voltage amplitude up to 100 kV, voltage switching time as short as 100 ps, PRF more than 100 kHz and efficiency up to 90%-95%. The implementation of such switches became possible due to a new approach to the processes of electron emission from cold cathodes in a gas discharge and the use of the electron runaway phenomenon in strong electric fields in special gas discharge conditions, called open discharge (OD) [14]. Also, construction of such type of the switches makes it possible to enhance possibilities of plasma parameters control.…”