Generation and radiation of ultra-wideband electromagnetic pulses with high stability and effective potential

Pulsed discharges in high-pressure gases are of considerable interest as sources of nonequilibrium plasma for various technological applications: pollution control, pumping of laser media, plasma-assisted combustion, etc. Recently, attention has been attracted to the use of subnanosecond voltage fronts, producing diffuse discharges with radii of several millimeters. Such plasma structures, similar to pulsed glow discharges, are of special interest for applications due to quasi-uniformity of plasma parameters in relatively large gas volumes. This review presents the results of experimental and computational study of subnanosecond diffuse discharge formation. A description of generators of short high-voltage pulses with subnanosecond fronts and of discharge setups is given. Diagnostic methods for the measurement of various discharge parameters with high temporal and spatial resolution are described. Obtained experimental data on plasma properties for a wide range of governing factors are discussed. A review of various theoretical approaches used for computational study of the dynamics and structure of fast ionization waves is given; the applicability of conventional fluid streamer models for simulation of subnanosecond ionization waves is discussed. Calculated spatial-temporal profiles of plasma parameters during streamer propagation are presented. The efficiency of subnanosecond discharges for the production of reactive species is evaluated. On the basis of the comparison of simulation results and experimental data the effects of various factors (voltage rise time, polarity, etc.) on discharge characteristics are revealed. The major physical phenomena governing the properties of subnanosecond breakdown are analyzed.

Section: Experimental Setupsmentioning

confidence: 99%

Subnanosecond breakdown in high-pressure gases

Naidis

Тарасенко

Babaeva

et al. 2018

“…But in the subnanosecond range, you can also get completely unique effects. For example, using shorter pulses to generate electromagnetic radiation allows to perform ultra-wideband radiolocation [15]. Subnanosecond electron beams and x-ray radiation are unique tools for studying the physics of the interaction of radiation with matter, when the pulse action time becomes comparable and even less than the characteristic times of some transition processes in gases and solids [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the switching characteristics of high-pressure subnanosecond gas dischargers with the purpose of a sharp increasing of the breakdown voltages and the switching speed

Ivanov¹

2022

The paper analyzes the data obtained in the subnanosecond time range on the times (t br) and speeds (V br) of switching of hydrogen diode dischargers. These data were obtained in a wide range of hydrogen pressures (p) and the degree of the discharge gap overvoltage (the length of the cathode-anode gap d) in a uniform electric field. It is shown that the reduced strength of the average electric field E br/p in the discharge gap at the moment of the beginning of the breakdown significantly decreases when the gas pressure increases from 5 atm to 50 atm. An increase in pressure from 50 atm to 60 atm leads to a sharp (by 40–135%, depending on the d) increase in the pulse breakdown voltage (U br) and an increase in E br/p. In proportion to the growth of E br/p the switching speed V br of the discharge gas gap increases. The observed effect is explained by the change in the discharge initiation mechanisms. The limitation of U br and V br in the hydrogen pressure range from 5 atm to 50 atm occurs as a result of gas ionization by runaway electrons and the subsequent development of a multi-avalanche discharge in the volume of the discharge gap. With a further increase in pressure, the discharge develops according to the streamer type. To design ultrafast gas dischargers of the subnanosecond range intended for switching high voltages, it is necessary to select an appropriate range of working gas pressures in order to ensure the development of a streamer-type discharge.

“…From the practical standpoint, these investigations are motivated by the need of creating ultrafast switches [28,29] and pulsed sources of electron, plasma, or x-ray beams [30][31][32]. It is also important to increase the breakdown strength of high-voltage gas feeder paths and shock-excited antenna systems [33]. In all of these studies, a special place is given to the phenomenon of electron runaway appearing at the breakdown delay stage [5,34].…”

Section: Introductionmentioning

confidence: 99%

Mechanism and dynamics of picosecond radial breakdown of a gas-filled coaxial line

Зубарев¹,

Kozhevnikov²,

Kozyrev³

et al. 2020

High-voltage picosecond breakdown of an atmospheric-pressure air-filled coaxial line in the radial electric field of a propagating transverse electromagnetic wave has been studied both experimentally and theoretically. On the one hand, we demonstrate that gas preionization by runaway electrons (RAEs) plays a decisive role in the breakdown development process: the breakdown delay time drastically increases in the absence of RAEs. On the other hand, it is established that, for sufficiently short pulses, the radial gap switching process does not have enough time to develop even in a situation where the RAE flow is effectively generated. Fundamental limitations on the breakdown strength of gas coaxial feeders imposed by this effect are discussed.