High Current Electron Beam Source Research Articles

Development of high performance, high-current pulsed electron beam sources

As a core part, the performance of a high-current electron beam source is inevitably essential for high-power sources and accelerators. The attractive features are high-electric field vacuum interface, high quality high current density electron emission, and high peak thermal load collector, which are compatible with high repetition rate operations. This paper presents an optimized ceramic insulation structure with hold-off voltage pulse of 600 kV, 100 ns, and 5 Hz. Mechanisms and surface improvements are developed. Large-scale, well-aligned SiC nano-wires as high-current, pulsed electron beam emitters are explored. They show an superior advantage on cathode lifetime and emission quality. In addition the thermal control and cooling methods for a repetitively operated high current collector are gathered, and the specially designed device can work stably with a heat flux of 1012 W/m2. These efforts make solid contributions to the HPM sources for practical use.

Generation of Low-Energy High-Current Electron Beams in Plasma-Anode Electron Guns

This paper is a review of studies on the generation of low-energy high-current electron beams in electron guns with a plasma anode and an explosive-emission cathode. The problems related to the initiation of explosive electron emission under plasma and the formation and transport of high-current electron beams in plasma-filled systems are discussed consecutively. Considerable attention is given to the nonstationary effects that occur in the space charge layers of plasma. Emphasis is also placed on the problem of providing a uniform energy density distribution over the beam cross section, which is of critical importance in using electron beams of this type for surface treatment of materials. Examples of facilities based on low-energy high-current electron beam sources are presented and their applications in materials science and practice are discussed.

强流电子束源阴极等离子体的粒子模拟

强流电子束源阴极等离子体的粒子模拟

Robust, easily shaped, and epoxy-free carbon-fiber-aluminum cathodes for generating high-current electron beams

This paper presents the construction of carbon-fiber-aluminum (CFA) cathode by squeezing casting and its applications for generating high-current electron beams to drive high-power microwave sources. The fabrication process avoided using epoxy, a volatile deteriorating the vacuum system. These cathodes had a higher hardness than conventional aluminum, facilitating machining. After surface treatment, carbon fibers became the dominator determining emission property. A multineedle CFA cathode was utilized in a triode virtual cathode oscillator (vircator), powered by a approximately 450 kV, approximately 400 ns pulse. It was found that 300-400 MW, approximately 250 ns microwave was radiated at a dominant frequency of 2.6 GHz. Further, this cathode can endure high-current-density emission without detectable degradation in performance as the pulse shot proceeded, showing the robust nature of carbon fibers as explosive emitters. Overall, this new class of cold cathodes offers a potential prospect of developing high-current electron beam sources.

Propagation of individual plasma spots on cathode surface by high-current discharge process

In this Letter, plasma distribution on a carbon-fiber–aluminum (CFA) cathode powered by a ∼450 kV, ∼350 ns, ∼ 50 Ω HV pulse generator is investigated by time-and-space-resolved electrical and optical diagnostics. A quasi stationary behavior of cathode plasma expansion into the vacuum gap was observed during the main pulse. The cathode plasma distribution is characterized by individual plasma spots. It was shown by optical and X-ray measurements that the uniformity of the extracted electron beam is satisfactory in spite of the individual plasma spots. A mechanism for this phenomenon is suggested. Relativistic electron beams, with the current densities up to 340 A/cm 2, were obtained. This class of CFA cathode may offer the promising prospect of high-current electron beam sources.

A Wide-Aperture, Low-Energy, and High-Current Electron Beam Source with a Plasma Anode Based on a Reflective Discharge

A source of low-energy (10–30 keV) high-current (up to 30-kA) electron beams efficiently and stably operating under conditions of oil-free vacuum has been developed. It is based on an electron gun with an explosive-emission cathode and a plasma anode, which is formed using a high-current reflective discharge. An external guide magnetic field ensures both discharge initiation and maintenance and beam transport. The source, the results of tests of it, and the experience of its operation are described. Methods for reducing the flow of erosion products ejected from the walls of the vacuum chamber to the processed target are proposed. The source is used in physical and technological studies of the modification of properties of surface material layers and for surface processing of articles.