Влияние анодной и катодной плазмы на работу электронного диода со взрывоэмиссионным катодом

The results of modeling and experimental investigation of the formation of anode and cathode plasmas in a vacuum diode with an explosive-emission cathode during the generation of a pulsed electron beam with a current density of 0.3-0.4 kA/cm^2 and an accelerating voltage of 300-500 kV are presented. It is shown that the concentration of the anode plasma does not exceed 10^10 cm^-3 and it does not significantly contribute to the operation of the diode. However, the complete desorption of molecules from the working surface of the explosive-emission cathode and the high efficiency of shock ionization of atoms ensure the formation of a cathode gas plasma with a concentration of 10^16 cm^-3. It is found that the charge of the explosive-emission plasma layer is significantly less than the charge of the electron beam and the main source of electrons is not an explosive-emission plasma, but a cathode gas plasma. In this case, the electron current is limited by the concentration of the cathode plasma. The use of a cathode with a developed surface (a cathode with a carbon fabric coating) allows increasing the total charge of the electron beam by more than 1.5 times without changing the cathode diameter and the anode-cathode gap.

Measurement of the electron beam energy in a source with a plasma anode and the beam extraction into the atmosphere through a foil window

Measurements of the energy of an electron beam in an electron beam source with an explosive-emission cathode, a plasma anode and a foil window, providing the extraction of an electron beam with a cross-section of (100–200) cm2 into the atmosphere, have been performed. The high voltage source was a Marx generator based long lines with matched loads. The energy values were calculated from the results of measurements of the temperature of a beam collector placed in vacuum using thermistors and an infrared imager. At an accelerating voltage of ~ 200 kV, a current of (1–2) kA, and an electron beam duration of 5 μs, the maximum values of the energy released in the collector with a cross section of 74 cm2 were (650–850) J/pulse. A decrease in the current and energy of the beam was recorded approximately by a factor of two after passing through an AMG-2n aluminum-magnesium foil with a thickness of 30 μm. The use of infrared imager for recording the beam structure in the plane of the output window in air has been tested.

Токовые характеристики сильноточной электронной пушки с многоканальным инициированием взрывной эмиссии пробоем по поверхности диэлектрика

Current characteristics of a plasma-filled, high-current electron gun with a new cathode assembly which can be named as a controlled explosive-emission cathode have been investigated. Multi-gap initiation of explosive emission is performed with the use of parallel operated, resistively decoupled arc plasma sources which electrodes and tube ceramic isolators are built-in to the explosive-emission cathode. The initiation of explosive emission was performed using 69 operating in parallel arc plasma sources whose electrodes and tubular ceramic insulators are inserted to the disk explosive-emission cathode. Experiments have demonstrated operability of high-current electron gun with a new cathode assembly at accelerating voltage up to 30 kV and its good emissivity (average in area current density) which was approximately 1.4–2.4 times higher than an emissivity of traditional electron gun with plasma anode and multi-wire copper cathode.

Катодный узел сильноточной электронной пушки с многоканальным инициированием эмиссии пробоем по поверхности диэлектрика

A new scheme of the cathode assembly of a high-current electron gun is presented. Initiation of explosive emission is performed with the help of sixty nine simultaneously operating spark gaps which electrodes and tube ceramic isolators are inserted into a disc explosive-emission cathode. The operability and high emissivity of the cathode assembly which exceeds by 1.5‒1.7 times the value inherent in traditional scheme of an electron gun with plasma anode and copper-braid explosive-emission cathode has been demonstrated.

Характеристики сильноточной электронной пушки с плазменным анодом на основе гибридного разряда

In the paper, the results of the study of space structure and temporal dynamics of a hybrid discharge matching a high-current reflective discharge with vacuum arcs initiated by surface dielectric flashover at the discharge supplying voltages up to 9 kV and working gas (argon) pressures of 0.1 – 1 mTorr are presented. The possibility of the formation of plasma anode with the density increased at the periphery including the use of an auxiliary screen has been demonstrated. The measurements of energy density distribution of a low-energy, high-current electron beam formed in an electron gun with explosive-emission cathode and plasma anode based on this hybrid discharge are also presented. The results obtained are comparable with those achieved with the use of magnetic field concentrators. Since the use of concentrators is not always possible, so the suggested method of the beam uniformity improvement looks promising.