Supershort electron beam from air filled diode at atmospheric pressure

Abstract

The properties of an electron beam~e-beam! formed in air under atmospheric pressure are reported. The nanosecond generators RADAN-303~two devices! and RADAN-220, producing nanosecond voltage pulses with amplitude of up to 400 kV and subnanosecond rise time were used in the experiments. It was shown for the first time that the duration of e-beam current of gas diode behind the foil does not exceed 0.1 ns. The maximum amplitude of current of a supershort avalanche electron beam~SAEB! behind the foil was ;400 A. The data on the influence of various parameters on e-beam current amplitude measured behind the foil were obtained. An electron beam with energy less than 60 keV and powerful X-ray radiation were formed in discharge gap simultaneously with SAEB.

Reconstruction of electron beam energy spectra for vacuum and gas diodes

“…Now, the most divergent spectral measurement data are those for supershort avalanche electron beams (SAEBs) produced in point-to-plane gaps in atmospheric pressure air. According to our studies, the spectrum of a SAEB generated in atmospheric pressure air can sometimes reveal two to three groups of electrons differing in energy (Bakhst et al, 2008a;2009;Tarasenko, 2011;Tarasenko et al, 2005;2008;2011;2013). Electrons of the first (low-energy) group have kinetic energies T 1 < eU m /3; those of the second (main) group have energies eU m /3 < T 2 < eU m ; and electrons of the third group, which are termed electrons with "anomalous" energy (Babich & Loiko, 1985), have energies T 3 > eU m .…”

Modification of the near-surface layers of a copper foil under the action of a volume gas discharge in air at atmospheric pressure

“…The beam energy spectrum in a diode used in the present study contained electrons with energies from 40 to 180 keV. It should be noted that electrons with the energies below 40 keV cannot be detected by the method employed in [9,12], although calculations [13,14] show that a considerable fraction of particles with such energies must be formed in the discharge plasma. The samples of copper foil were irradiated in a periodic pulse regime at a pulse repetition rate of 1 Hz.…”

“…For electrons with energies above 70 keV and a current pulse width (FWHM) of ~0.1 ns (which corresponded to the given collector resolution), the current pulse amplitude was ~10 A. The electron energy distribution measured in an analogous diode filled with air at atmospheric pressure was reported elsewhere [9,12]. The beam energy spectrum in a diode used in the present study contained electrons with energies from 40 to 180 keV.…”

“…It should be noted that, while the conditions of UAEB-induced volume discharge formation admit broad variation of the voltage pulse duration and amplitude and the cathode design [6,[8][9][10][11][12][13][14], the generation of a runaway electron beam requires the optimization of a number of parameters [9]. The present study was not aimed at studying the surface modification of copper under the conditions of runaway electron beam formation with maximum amplitude.…”

“…Another feature of volume discharges in inhomogeneous electric fields, which are initiated by ultrashort avalanche electron beams (UAEBs), is the possibility of reaching high levels of specific power (up to 800 MW/cm 3 [8]) deposited in the discharge. In such regimes, runaway electron beams emitted from the discharge plasma are characterized by the beam current amplitudes reaching tens and hundreds of amperes (behind the foil), while the current pulse duration (defined as the pulse full width at half maximum, FWHM) does not exceed 100 ps [9]. Such discharges in inert gases are also accompanied by high-intensity vacuum ultraviolet (VUV) emission [10].…”