Cumulation of High-Current Electron Beams: Theory and Experiment

Abstract

A drastic cumulation of current density caused by electrostatic repulsion in relativistic vacuum diodes with ring-type cathodes is described theoretically and confirmed experimentally. The distinctive feature of the suggested cumulation mechanism over the conventional one, which relies on focusing a high-current beam by its own magnetic field, is a very low energy spread of electrons in the region of maximal current density that stems from a laminar flow profile of the charged-particle beam.

Electrostatic cumulation of high-current electron beams for terahertz sources

“…For this reason, in further experiments we placed 70 µm-thick aluminium foil in front of the dosimetry film to decrease the absorbed dose (see Fig. 3) [7]. This enables us to cut off the flows of both the cathode plasma and the weakly-relativistic electrons produced at the voltage pulse decay.…”

“…As a result, the accelerated motion of electrons toward the anode comes alongside the radial motion to the cathode's symmetry axis. As a result, the high-current beam density increases multifold on the axis as compared to the average current density in the cathode-anode gap [7,8]. spot on the anode at the moment corresponding to the maximum accelerating voltage is as large as 10 A/mm2, being 5 times greater than the average current density of the high-current diode.…”

“…To obtain information about electron beam parameters, we use a nanosecond pulse-periodic electron accelerator with a compact SF6-insulated high-voltage generator providing pulsed voltage up to 400 kV in 30 Ohm resistive load with a full width at half maximum of 130 ns and rise time of 30 ns [7]. To obtain full-sized imprints of electron beams, we use a radiochromic dosimetry film placed 3 mm behind the anode mesh made of stainless steel (the geometrical transparency of the mesh is 0.77); the cathode-anode gap is 20 mm.…”

“…This paper considers one more alternative for highcurrent electron beam cumulation, namely electrostatic cumulation [7,8]. Occurring in a relativistic vacuum diode with a ring-type cathode, this mechanism doesn't suffer from particle energy spread [8].…”

Исследование Параметров Самосфокусированного Электронного Пучка, Выведенного За Анод Вакуумного Диода

“…Стимулом проведения таких исследований является общенаучный интерес к двум проблемам: необходимости изучения поведения конденсированных сред при высоких плотностях энергии и получению новых данных о физической природе таких явлений, как филаментация и самофокусировка электронных пучков в диодах со взрывоэмиссионным катодом, механизмы формирования которых окончательно не установлены. Отсутствие последовательной теории явлений филаментации и самофокусировки электронных пучков в вакуумных и газовых диодах сильноточных электронных ускорителей с различными параметрами стимулировало проведение экспериментальных работ, основанных на различных модельных представлениях [1,4,[6][7][8][9][10][11].…”