Electron beam generation with variable current amplitude during its pulse in a source with a grid plasma cathode

Abstract

In electron sources with grid plasma cathodes, the boundary of the emission plasma is stabilized by a fine-structured grid, the cell size of which is comparable to the size of the Langmuir layer. The correct choice of the cell size of the emission grid allows to stabilize of the emission plasma boundary, reaching a wide range of the parameters adjustment of the generated electron beam with a weak dependence of these parameters on each other. Since the beam current amplitude is most often controlled by a proportional change of the discharge current in the plasma cathode, which allows to change the emission plasma concentration, this paper is investigated the possibility of generating the electron beam having variable amplitude by predicting the change in the discharge current amplitude during its pulse. The described advantage of plasma cathodes makes it possible to obtain electron beams with both a falling and a rising current amplitude of the beam during its pulse. The obtained regimes of electron beam generation open up new possibilities for using this source for both scientific and technological purposes.

Динамическое Управление Мощностью Мегаваттного Электронного Пучка Субмиллисекудной Длительности В Источнике С Плазменным Катодом

“…С учетом данной особенности источников с плазменным катодом в работе [14] были проведены теоретические оценки, подтверждающие возможность генерации электронного пучка миллисекундной длительности, мощность которого можно контролируемо изменять в течение импульса. Проведенные оценки позволили создать источник электропитания плазменного катода [15] и экспериментально продемонстрировать, что путем динамического изменения тока разряда, а следовательно, и концентрации эмиссионной плазмы [7] возможно осуществлять пропорциональное динамическое изменение тока пучка непосредственно во время импульса. Целью настоящей работы является демонстрация возможности динамического управления мощностью пучка мегаваттного уровня в течение импульса субмиллисекундной длительности.…”

“…Как и в [15], в настоящей работе использовался источник электронов " СОЛО" с сетчатым плазменным катодом и плазменным анодом с открытой плазменной границей [16], входящий в перечень уникальных установок России в составе комплекса " УНИКУУМ". Важно отметить, что средняя за импульс плотность энергии электронного пучка во всех трех случаях была специально подобрана одинаковой и составляла 25 J/cm 2 , что было экспериментально измерено с помощью калориметра, подробно описанного в [17].…”

Dynamic Power Control of a Submillisecond Pulsed Megawatt Electron Beam in a Source with a Plasma Cathode

“…In view of these properties of beam sources with a plasma cathode, we have performed simulations [14] and obtained theoretical estimates that confirmed the possibility of generating pulsed beams of millisecond duration with controlled power variation during the pulse. Using these estimations, we have recently created a source of power supply for a plasma cathode [15] and experimentally demonstrated that, by means of dynamic variation of the discharge current and, hence, the concentration of emissive plasma [7], it is possible to provide proportional dynamic variation of pulsed electron beam current during the pulse.…”

“…The present work was aimed at demonstrating the possibility of dynamic power control of a submillisecond pulsed electron beam during its pulse. The experiments were performed using electron beam source of the "SOLO" [15] type with a grid plasma cathode and plasma anode with an open plasma boundary [16]. This electron source is a unique facility developed in Russia and is part of the UNIKUUM complex.…”

“…The new scheme of power supply to a plasma cathode (described in more detail elsewhere [15]) generates an arc discharge current that is amplitude-modulated during a submillisecond pulse, which provides variation of the emission plasma concentration on the same time scale. It is important to note that this scheme also provides an interval within several dozen microseconds between discharge current pulses, which can also be necessary during the irradiation of inorganic material surfaces for controlled modification of their structure and phase state.…”