Pulsed plasma electron sources

Abstract

There is a continuous interest in research of electron sources which can be used for generation of uniform electron beams produced at E≤105 V/cm and duration ≤10−5 s. In this review, several types of plasma electron sources will be considered, namely, passive (metal ceramic, velvet and carbon fiber with and without CsI coating, and multicapillary and multislot cathodes) and active (ferroelectric and hollow anodes) plasma sources. The operation of passive sources is governed by the formation of flashover plasma whose parameters depend on the amplitude and rise time of the accelerating electric field. In the case of ferroelectric and hollow-anode plasma sources the plasma parameters are controlled by the driving pulse and discharge current, respectively. Using different time- and space-resolved electrical, optical, spectroscopical, Thomson scattering and x-ray diagnostics, the parameters of the plasma and generated electron beam were characterized.

Electron-beam accelerator for pumping of a Xe2 lamp

“…The electron beam is usually generated from an explosive emission cold cathode and extracted into a lasing gas through a thin metallic foil. Detailed investigation of several types of passive and active cathodes (metal ceramic, velvet, carbon fiber, multicapillary and multislot cathodes, and active ferroelectric and hollow anodes plasma sources) was reported by Krasik et al (2009). The cathodes are typically driven by pulsed power generators of 500-700 kV voltage and of hundreds of kiloamperes, with pulse duration up to 1 μs.…”

High-current diode with ferroelectric plasma source-assisted hollow anode

“…The main advantages of this source are an almost unlimited lifetime, possible operation in dc mode, low-background pressure, radial current density uniformity of the extracted electron beam, operational simplicity, and compactness. 4,10 Moreover, the fact that the cathode plasma ͑i.e., the HA discharge plasma͒ is formed prior to the application of the accelerating pulse allows one to avoid time delay in the beginning of the generation of the electron beam with respect to the accelerating pulse. Using nondisturbing spectroscopic, 11 Thompson scattering, 12 and laser induced fluorescence techniques, 13 time-and space-resolved parameters of this plasma were studied in detail and it was shown that the FPS continuously generates the plasma during the HA discharge without additional energy consumption.…”

“…[1][2][3][4] In general, several types of electron guns that operate with different types of cathodes ͑thermionic, field emission, explosive emission, and hollow cathode/anode cathodes͒ can be used to generate this type of electron beam. However, thermionic and field emission cathodes require high and pure vacuum conditions and an extremely large electric field ͑E Ͼ 10 7 V / cm͒ in order to extract electron beams with a significant ͑Ͼ1 A/ cm 2 ͒ current density when a field emission cathode is used.…”

Numerical study on rectangular microhollow cathode discharge

“…1,2 The cathode can be built in different shapes, typically a pair of plane parallel plates or a cylindrical cavity, while the anode is placed at the ends of the cathode. In appropriate conditions, the negative glows from facing cathode surfaces overlap, and some energetic electrons may "oscillate" between the opposing cathodes.…”