The author presents a bibliography covering the field of electrical discharges in vacuum, comprising both electrical breakdown in vacuum and vacuum arcs. A brief section lists some review papers which would be helpful to the novice in this field. The bulk of the presentation consists of bibliographic listings arranged by year of publication and alphabetically by author within each year. An author index refers one to all papers authored or coauthored by a particular person. >

Electrical discharges in vacuum: 1980-90

The results of experiments on the generation of high-power microsecond electron beams in an electron beam source with an explosive-emission cathode, a plasma anode, and output of an electron beam through a foil window into the atmosphere are presented. The beam is formed and transported in the presence of a longitudinal magnetic field. The power source is a Marx generator with matched loads and with a rectangular waveform of the output voltage pulse. At an accelerating voltage of 200–220 kV, in an electron beam source, the electron beams with a current of up to 2.5–3 kA, a cross section of 100–200 cm 2 , and a duration of 5 µs are obtained without ignition of the arc discharge in the interelectrode gap. The possibility to realize operation modes of an electron beam source without beam rotation is demonstrated. The energy released on the beam collector with a receiving surface area of 74 cm 2 , located in the electron source behind the anode, is up to ~ 600–700 J/pulse. The beam energy extracted outside of the foil is registered with calorimeters and equals to ~ 250–270 J/pulse.

Application of a Plasma Anode in the Electron Beam Source with an Explosive Emission Cathode and Electron Beam Output into the Atmosphere

Conduction and breakdown in vacuum

Intense electron beams with pulse duration on the level of microseconds have been utilized in a number of areas, including the production of free electron laser, material surface modification, and high-energy-density physics research. The high-voltage pulse forming technology based on metal oxide varistors (MOVs) has been verified to be an effective way to produce quasi-square pulses in recent years. In this article, a high-energy-density Marx generator with output waveform modified by a flat-top compensation LC filtering branch and a low inductance MOV folding structure was designed and tested to generate microsecond pulses. Experimental results show that a quasi-square pulse with a voltage amplitude of more than 500 kV and a pulsewidth of $1~\mu \text{s}$ was obtained on a dummy load of $50~\Omega $ . Further experimental research was carried out using a magnetically insulated coaxial diode (MICD) electron beam diode, and as a result, a relativistic electron beam with an energy of 550 keV, a current of 8.3 kA, a rise time of less than 40 ns, and a flat-top of about 600 ns was produced. The Marx generator with a modified waveform has the advantages of simple design, compact construction, and high-quality flat-top, which is a good platform for the generation of intense microsecond electron beams.

The Generation of Intense-Relativistic-Microsecond Electron Beams From a High-Energy-Density Marx Generator With Waveform Modification

Optical studies of metal ceramic cathode demonstrated that the intensity of plasma light emission of the surface of the MC plate before the current maximum was below the sensitivity threshold of the 18ELU photoelectric intensifier, despite the presence of plasma sufficient for the significant magnitude of the amplitude (up to 500 A) and growth rate of the beam current (up to 20 A/ns). This confirms that the feature of the plasma occurring on the surface of the MC plate is a large emission surface at low density, the light emission of which cannot be recorded by the photoelectric intensifier, except in cases of significant current growth and current density at small anode–cathode distances and with a trimmed MC plate. Measurements of the plasma light emission spectrum of the MC cathode showed that emission plasma is generated during discharge, both from stainless steel particles and from the ceramic base material, with traces of strongly ionized ions presumably visible. This confirms the significant impact of processes occurring precisely in the gap around the metal particles on the MC cathode operation. Studies using an electron-optical converter showed that the separation of plasma from the surface of the MC plate occurs at a rate of more than 2.5 cm/ μ s. It is shown that the amplitude of the pre-pulse for various high voltage pulse shaping circuits of accelerators was impact on kinetics of plasma formation and light emission on the MC cathode.

Optical studies of metal ceramic cathode

Microdischarges on the surface of a dielectric in a vacuum

A new high-power source of electrons with plasma anode for producing high-current microsecond electron beams with electron energy up to 400 keV has been developed, manufactured, and put in operation. To increase the cross section and pulse current duration of the beam, a multipoint explosive emission cathode is used in the electron beam source, and the beam is formed in an applied external guiding magnetic field. The Marx generator with vacuum insulation is used as a high-voltage source. Electron beams with electron energy up to 300–400 keV, current of 5–15 kA, duration of 1.5–3 μs, energy up to 4 kJ, and cross section up to 150 cm2 have been produced. The operating modes of the electron beam source are realized in which the applied voltage is influenced weakly on the current. The possibility of source application for melting of metal surfaces is demonstrated.

Microsecond Electron Beam Source with Electron Energy Up to 400 Kev and Plasma Anode

Experiments have been carried out to obtain high-power microsecond electron beams with high energy using an electron beam source with an explosive emission cathode and a plasma anode. The beam was formed and transported in a longitudinal magnetic field. The voltage source was the Marx generator with stages based on artificial long lines with matched loads connected to them. The possibility of realization of operation modes of the electron beam source with quasi-constant values of the accelerating voltage and current without highcurrent arc discharge formation in the interelectrode gap is demonstrated. Electron beams with circular and rectangular cross sections of ~100–200 cm2 with current up to 1–1.5 kA and duration of 5 μs were obtained at a quasi-constant accelerating voltage of 200 kV. The rotation of the beam around its axis was recorded. The possibility of electron beam extraction through a foil window into the atmosphere has been tested.

Obtaining of High-Power Electron Beams in a Plasma Anode Source Powered by the Marx Generator with Matched Loads

The interaction of the plasma formed at emission centers of an electron source using explosive electron emission with the cathode surface is studied. It is found that the plasma flux does not flow around obstacles located in its path and is effectively deionized upon incidence on the wall.

Interaction of cathode plasma with the cathode surface in an electron source with explosive electron emission

The approximation of electron motion along electric field force lines is used to calculate current in diodes with knife-edge and point emitters. The diode current is limited by space charge, with each current tube considered as a diode element with electrodes in the form of coaxial cylinders or concentric spheres. The effect of the cathode cavity in which the emitter is installed upon current magnitude is considered by limiting beam dimensions at the anode.

É. N. Abdullin

Papers

Microdischarges on the surface of a dielectric in a vacuum

Microsecond Electron Beam Source with Electron Energy Up to 400 Kev and Plasma Anode

Obtaining of High-Power Electron Beams in a Plasma Anode Source Powered by the Marx Generator with Matched Loads

Interaction of cathode plasma with the cathode surface in an electron source with explosive electron emission

Approximate calculation of current in a diode with an explosive emission cathode