Specifics of the focused electron beam transport in the forevacuum range of pressure

Abstract

We have investigated electron beam transport at an elevated forevacuum pressure of tens of Pascals of helium. The continuous electron beam (6–14 keV, 300 mA) is generated by a forevacuum-pressure plasma-cathode electron source utilizing a hollow-cathode discharge. A beam-plasma discharge is generated in the beam transport zone, which is characterized by increased plasma density in the region of the most intense beam-plasma interaction. We find that the location and distribution of the beam-plasma discharge depend on the electron beam energy and current density. Under certain conditions, we observe that the beam plasma is stratified, with a periodic variation of plasma density and luminosity along the direction of electron beam propagation.

Powerful electron beam transport from a plasma–cathode electron source at forevacuum pressure

“…Increasing the electron beam current to I e = 120-150 mA changes the character of the plasma glow: there appear along the beam trajectory separate bright glowing regions, resembling the strata of a glow discharge. We have observed these plasma formations previously, as reported [13]. The most probable cause of these formations is development of a beam instability which ignites a beam-plasma discharge (figure 2(b)) [13].…”

“…We have observed these plasma formations previously, as reported [13]. The most probable cause of these formations is development of a beam instability which ignites a beam-plasma discharge (figure 2(b)) [13]. In the case of a beam-plasma discharge, in addition to pair interactions, a collective interaction between the electron beam and the plasma system manifests itself.…”

“…The measured collector temperature for this case was about 400 • C. An obvious reason for this temperature decrease occurring at higher initial beam power is the energy lost by beam electrons from build-up of plasma oscillations and from beam expansion due to interaction with plasma. For the case of lower beam power, which we have studied and reported on earlier [13], the effect of bulk plasma ignition is weaker and no bright plasma glow is observed.…”

Electron-Beam Synthesis of Dielectric Coatings Using Forevacuum Plasma Electron Sources (Review)

“…As noted by the authors in [119], the observed alternation of dark The observed phenomenon resembles strata, i.e., static or movable fringes of uneven luminosity alternating with dark bands in the positive column of a low-pressure gas discharge [120,121]. As noted by the authors in [119], the observed alternation of dark and bright bands, similar to strata, exists in a very narrow interval of the beam current and electron energy and may be related to the emergence of beam instability.…”

“…The increase in the concentration is accompanied by an enhanced plasma glow [118]. Paper [119] presents the measurements of the parameters of the beam plasma generated during the propagation of a focused electron beam with an energy of up to 15 keV and a beam current of up to 300 mA in a helium atmosphere at a pressure of up to 50 Pa. The schematic diagram of the setup and the distribution of plasma concentration is shown in Figure 15.…”