An experimental and theoretical study is carried out to control the distribution of electron beam current density in a SOLO source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the emission plasma boundary. It has been shown experimentally and numerically that using a control electrode in the form of a disk (disks) in the plasma cathode and a leading magnetic field, it is possible to change the distribution of the emission current density and, accordingly, the energy density of the electron beam on the collector. Theoretical study using the envelope method, “particle-in-cells” method and drift-diffusion models shows good agreement with experiment.

In a source with a plasma grid cathode based on a low-pressure arc with layer stabilization of the emission plasma boundary, a method of combined control of the electron beam current during a submillisecond pulse of its generation has been developed. A diagram of power supplies and their connection to the electrodes of the electron source is presented, as well as oscillograms demonstrating the possibility of an extended range of control of the power of the electron beam by changing the concentration of the emission plasma by adjusting the discharge current, with a simultaneous change in the width of the ion layer at the surface of the emission grid due to grid control when applying a potential bias to an additional grid electrode. Expanding the power range of the generated beam opens up new opportunities for the use of electron sources of this class for both scientific and industrial purposes.

We described the methods of combined hardening of the surface of samples made of die steel grade 3Kh2V8F. To this end, the samples were exposed to thermal-chemical treatment—boroaluminizing, and the resulting diffusion layer was modified by the method of pulse beam treatment using an electron source with a plasma cathode. The study aims to investigate local structural-phase transformations of the boride diffusion layers due to high-speed heating by a millisecond duration electron beam. The diffusion layer structures after boroaluminizing and subsequent pulse beam treatment were compared. In addition, microhardness and surface topography were studied, and the phase state of the diffusion layer was assessed before and after electron beam treatment.

The article presents the study of the effect of pulsed electron beam treatment on the surface roughness of samples made of titanium alloy VT-6, obtained by two methods: mechanical processing and additive manufacturing. It has been established that electron beam treatment allows reducing the roughness of titanium alloys in both cases, which can be extremely important for polishing small-sized products, particularly those with low mechanical strength or unique microrelief surface.

Using the example of an electron source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the cathode/emission plasma boundary and an open anode/beam plasma boundary, a mechanism is described for increasing the electrical strength of a high-voltage accelerating gap by introducing a series negative current feedback (NCF) in the accelerating interval, which makes it possible to level out uncontrolled bursts of the beam current during its pulse. The introduction of NCF is achieved by using a special electrode in the space of the plasma emitter connected through a resistance to the anode of the arc discharge, and the main task of which is to intercept accelerated ions penetrating into the emitter from the high-voltage accelerating gap, due to which the current of electron emission from the arc discharge plasma decreases by a value proportional to the ion current in the accelerating gap. Since most sources and accelerators of electrons with plasma cathodes based on discharges of various types have a similar principle of operation, the use of this method will not only expand the limiting parameters of the generated electron beams, but also increase the stability of the operation of such electron sources, and, accordingly, beam irradiation of various materials and products.

On the example of an electron source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the cathode/emission plasma boundary and an open anode/beam plasma boundary, a new method of electron beam formation is described, in which an additional auxiliary arc discharge is ignited in the anode region of the source. Initiation of the discharge was carried out by the electron beam, and the discharge itself was supported by an additional power source, which represented a low-impedance artificial forming line included in the collector circuit. The dependence of the current in the accelerating gap on the current flowing in the collector circuit was obtained in the absence of the arc discharge current of the plasma cathode.

The paper proposes and experimentally demonstrates a method for estimating the coefficient of electron extraction from a plasma emitter based on a low-pressure arc discharge with layered/grid stabilization of the emission plasma boundary. The method is based on the exclusion of the emission current from the total current in the accelerating gap by "sharp" switching off the arc discharge current. The condition for the applicability of the method is an insignificant change in the concentration of the anode plasma during the cutoff of the discharge current pulse. The preliminary data obtained testify in favor of a change in the electron extraction coefficient by up to 20% during a discharge current pulse with a duration of 150 μs.

A niobium film on an AISI 5135 steel substrate was exposed to submillisecond pulsed electron-beam irradiation with controlled energy modulation within a pulse to increase the film–substrate adhesion. This modulated irradiation made it possible to dope the steel-surface layer with Nb through film dissolution in the layer, for which optimum irradiation conditions were chosen from experiments and a mathematical simulation. The irradiated system was tested for surface hardness and wear, and its surface structure and elemental composition were analyzed. The results demonstrate that the microhardness of the irradiated system is much higher and that its wear rate is much lower compared to the initial state.

В работе проводится экспериментальное и теоретическое исследование управления распределением электронного пучка в источнике «СОЛО».Показано, что с помощью управляющего электрода в форме диска (дисков) в плазменном катоде и ведущего магнитного поля можно изменять распределение плотности энергии электронного пучка на коллекторе.Теоретическое исследование с применением метода огибающей, метода крупных частиц и дрейфово-диффузионной моделей показывает хорошее согласие с экспериментом.

В данной работе были исследованы методы комбинированного упрочнения поверхности образцов из штамповой стали 3Х2В8Ф.Для этого был использован процесс химико-термической обработки -бороалитирование, а также последующая модификация полученного диффузионного слоя с помощью импульсного элек тронно-пучковой обработки (ИЭПО) с использованием источника электронов с плазменным катодом.Целью работы было исследование локальной структурно-фазовой трансформации боридных диффузионных слоев за счет скоростного нагрева электронным пучком миллисекундной длительности.В ходе исследования был про веден сравнительный анализ строения диффузионного слоя после бороалитирования и последующей модифи кации слоя ЭПО.Помимо этого

The article presents results of studying the dynamics of a submillisecond low-pressure arc discharge in an electron source with a grid plasma emitter and a plasma anode, as well as the formation of an electron beam generated by it in a guiding magnetic field. Measurements of the currents to the electrodes of the plasma emitter discharge system and to additional probes installed in it demonstrated the spatial rearrangement of the discharge with subsequent achievement of a quasi-steady shape of the current density distribution on the emission electrode. Analysis of the current oscillograms at the end of the discharge current pulse made it possible to estimate the contribution of the electron emission current from the plasma emitter to the total current in the accelerating gap in the mode when the measured beam current is equal to or exceeds the discharge current. The factors responsible for reducing the spatial inhomogeneity of the beam current density are determined, and recommendations are given for improving its uniformity.

Разработан метод комбинированного управления током электронного пучка в течение субмиллисекундного импульса его генерации в источнике с плазменным сеточным катодом на основе дуги низкого давления со слоевой стабилизацией границы эмиссионной плазмы.Приведены схема источников электропитания и их под ключение к электродам источника электронов, а также осциллограммы, демонстрирующие возможность управ ления мощностью электронного пучка как с помощью изменения концентрации эмиссионной плазмы, достига емой регулировкой тока разряда, так и с помощью изменения ширины ионного слоя у поверхности эмиссион ной сетки (сеточным управлением -с помощью введенного

Using the example of an electron source with a plasma cathode based on a low-pressure arc discharge with grid stabilization of the cathode/emission plasma boundary and an open anode/beam plasma boundary, a mechanism is described for increasing the electrical strength of a high-voltage accelerating gap by introducing a series negative current feedback (NCF) in the accelerating interval, which makes it possible to level out uncontrolled bursts of the beam current during its pulse. The introduction of NCF is achieved by using a special electrode in the space of the plasma emitter connected through a resistance to the anode of the arc discharge, and the main task of which is to intercept accelerated ions penetrating into the emitter from the high-voltage accelerating gap, due to which the current of electron emission from the arc discharge plasma decreases by a value proportional to the ion current in the accelerating gap. Since most sources and accelerators of electrons with plasma cathodes based on discharges of various types have a similar principle of operation, the use of this method will not only expand the limiting parameters of the generated electron beams, but also increase the stability of the operation of such electron sources, and, accordingly, beam irradiation of various materials and products.

Methods for controlling the electron beam power in a source based on a low-pressure arc discharge with layer stabilization of the emission plasma boundary are described. The control is carried out by the method of amplitude and latitude modulation within the duration of the submillisecond beam current pulse with a time resolution of 10 μs. Two ways to control the power of the electron beam are implemented: the first one is based on changing the concentration of the emission plasma by modulating the arc discharge current and the second method uses grid control (the mode of operation of the plasma triode) at the constant discharge current. Simplified diagrams of the power supply sources of the discharge and intergrid control voltage, typical oscillograms of the main currents of the discharge system, a graph of a quick-acting power change, and a control characteristic of a plasma triode are presented.

This work is a continuation of study [1] devoted to the effect of a submillisecond pulsed electron beam on the surface of hypereutectic silumin (AlSi20). Experiments are performed using a SOLO electron source with a plasma cathode in which the generated pulse power can be controllably changed during the pulse, which allows control of the energy-input rate to the target surface. The application of such a unique electron source enables consideration of the effect of maintaining the surface temperature of the irradiated sample (at a level close to the silumin melting point) at a pulse duration of less than 1 ms on modification of the properties of this surface. An increase in the time of maintaining the sample-surface temperature is shown to improve its microhardness and wear resistance. The modified layer has a cell structure similar to that formed during high-speed crystallization. The modified-layer depth reaches 60 μm.

In this article, the experimental and theoretical data are presented which demonstrate the possibility of controlling the specimen surface temperature during irradiation with a submillisecond electron beam produced by a plasma-cathode electron source. The specimen surface temperature is controlled by modulating the beam current via appropriate short-time variations in the emission plasma parameters. The temperature ripple factor, measuring less than 5% in our experiments, is defined as the product of the specimen surface temperature and the discretization degree of the beam current and its pulse duration. The efficiency of the method of temperature control is confirmed by numerical simulations. The proposed method opens the way to new applications of plasma-cathode electron sources in science and technology.

This work represents the investigations for decreasing acceleration gap breakdown probability of plasma source of electrons SOLO, with grid stabilization of the boundaries of the arc cathode plasma. We increased the distance to the treated target, bent the transportation channel of the electron beam, created additional plasma in the anode space, and increased the beam front. The effect of the above measures on the breakdown probability when the target is exposed of a low-energy electron beam with a power density of up to 0.5 MW/cm 2 with a diameter of 2.5 cm was investigated separately. Beam deflection is most effective at relatively long pulse durations of 150 μs and accelerating voltage of 20 kV, rather than a lower one. It was possible to double the maximum power for the same beam transport length applied to a low-melting target. Preionization in the anode proved to be effective for relatively short beams of 15 μs duration.

We describe a method for dynamic power control of a submillisecond pulsed electron beam in a “SOLO” type source with plasma cathode. The beam power is controlled by dynamic variation of the beam current amplitude with the corresponding low-inertia change in the concentration of emissive plasma. This method can be used to generate submillisecond electron beams of variable power (up to 10 MW at a maximum variation rate not exceeding 0.5 W/μs)—in particular, for the processing of various metallic materials with modification of their functional properties by controlled beam energy supply to the material surface.

The article presents the results of studies devoted to the study of the energy density distribution in the amplitude-modulated regime of electron beam generation. It is shown that in the first ≈ 50 μs of the duration of the beam current pulse, its spatial rearrangement occurs, due to the development of the arc discharge current. Thus, the rearrangement of the arc current, which develops from the axis of the system, leads to an axial diving of the emission current density and the beam current density on the target. With the development of the arc current, the energy density on the target on the axis of the system decreases and after ≈ 50 μs takes on a steady-state value, which can change only as a result of a change in the conditions for generating an electron beam or the transition to a modulated regime of electron beam generation. It has been experimentally shown using calorimetric measurements that the shape of the electron beam current pulse with its amplitude modulation with a pulse duration of more than 100 μs has little effect on the distribution of the beam energy density in the target region.