Physics of Plasmas · 1999 · 71 citations · 10 references
Natural SciencesElectrical EngineeringPhysicsElectromagneticsPlasma PhysicsRadiation PhysicsElectron Beam PhysicsPlasma FundamentalsPlasma SourcesArc DischargesBeam Current DensityBeam Pulse DurationCurrent DensityHollow Cathode DischargesHollow CathodesPlasma CathodesPulsed Electron Beams
Plasma cathode electron guns are attractive because they can produce high‑current, broad or focused beams in pulsed or steady‑state modes and, lacking a thermionic cathode, they offer long lifetime and reliable operation even in aggressive gas environments. This review surveys recent experimental research and development of plasma cathode electron guns, highlighting novel upgrades and applications across technology fields. Different plasma discharge systems—vacuum arcs, constricted gaseous arcs, hollow cathode glows, and Penning or magnetron crossed‑E×B discharges—are employed to meet specific beam parameter requirements. Plasma cathode electron guns can deliver transverse dimensions from fractions of a millimeter to about a meter, currents from microamperes to kiloamperes, current densities up to ~100 A/cm², pulse durations from nanoseconds to DC, and electron energies from several keV to hundreds of keV, enabling applications such as electron beam melting, welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, and microwave generation.
The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.
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