RU2100916C1 - Plasma accelerator - Google Patents

Abstract

FIELD: charge-particles accelerators, in particular, processing metal surfaces with high-power plasma flows, generation of heavy-power pulses of corpuscles. SUBSTANCE: device has electrodes which are connected to heavy- voltage power supply, igniting gas-discharge gap and coaxial acceleration channel. Electrodes of accelerator are designed as two hollow coaxial cylinders which are mounted with space between their ends which is used for ignition of discharge. Accelerating channel is shaped by electrodes and coaxial neutral conducting wire. EFFECT: increased output power of discharge, increased output plasma velocity, increased stability of operations. 1 dwg

Description

 The invention relates to plasma technology, and more particularly to devices for accelerating charged particles, and can be used, first of all, for processing high-energy plasma flows of metal surfaces in order to increase their characteristics such as surface cleanliness, microhardness, wear resistance, corrosion resistance, heat resistance , fatigue strength, etc. and also for the generation of powerful pulses of photon and corpuscular radiation.

 Known devices in which pulsed high-current gas discharges are used to accelerate a plasma, for example, a plasma accelerator [1] They consist of two coaxial electrodes connected to a high-voltage source of electrical energy and fixed from one end to the insulator. The discharge is initiated after applying high voltage to the electrodes along the surface of this insulator. The resulting plasma is accelerated by electrodynamic forces along the electrodes.

 Also known is a plasma accelerator [2] which contains coaxially mounted electrodes made in the form of two hollow cylinders and a central electrode (conductor) placed along the axis of symmetry of the accelerator. The electrodes are separated by insulators and connected to a high voltage source of electrical energy. The coaxial accelerator channel of the plasma accelerator contains a gas-discharge plasma initiation system (first stage) and an electromagnetic plasma acceleration system (second stage) and a plasma electromagnetic acceleration system (second stage).

 When high voltage is applied to the electrodes of the first stage, a gas breakdown occurs on the surface of the insulator and a current-plasma shell (TPO) is formed. After applying a high voltage to the electrodes of the second stage of the SST under the influence of electrodynamic forces arising from the interaction of the current flowing through the plasma layer with its own magnetic field, it begins to accelerate towards the open end of the channel, pushing and ionizing the working gas.

 The voltage at the electrodes during acceleration of the SST is determined by the impedance of the discharge system and increases as the SEC speed increases, therefore, to achieve high plasma velocities and reproducibility of the result from cycle to cycle, it is necessary to ensure a sufficiently high energy strength of the interelectrode gap behind the accelerated plasma.

 However, due to large heat fluxes on the surface of the insulator in the initial phase of the discharge and the inertia of the thermal processes, after the SST leaves the initial part of the accelerating channel, a significant amount of vapor of the material of the insulator with adsorbed working gas enters the interelectrode volume. Ionized by the radiation of an accelerated SST, this medium becomes electrically conductive and, thus, conditions are created for the formation of shunt current channels (leakage currents), which reduce the interelectrode potential difference. In addition, at the junction of the insulator with the internal coaxial electrode, where there is a large gradient of the electric field, secondary breakdowns that violate the acceleration regime of the main SST are initiated.

 The present invention aims to eliminate this drawback and, thus, to increase the integrated discharge power, plasma output speed and stability of the accelerator.

 To this end, the plasma accelerator electrodes are made in the form of two hollow coaxial cylinders located with a gap between their ends, which serves to initiate a gas discharge, and the accelerator channel filled with the working gas is formed by electrodes and a coaxially located electrically neutral conductor mounted on an insulator. Due to the fact that the initial breakdown of the gas does not occur on the surface of the insulator, the electric strength of the interelectrode gap at the TPO acceleration phase is significantly higher than in the known plasma accelerator, which is manifested in a decrease in leakage currents and the probability of secondary breakdowns.

 The drawing schematically shows the proposed plasma accelerator.

 Cylindrical coaxial electrodes 1, the ends of which are located with a certain gap relative to each other, are connected to a high voltage source including a capacitor bank 2 and a controllable spark gap 3. The inner conductor 4 is located along the axis of the system and overlaps the length of the gap between the electrodes. The reverse current lead 5 is made in the form of a series of pins located symmetrically relative to the axis of the system, to which a second electrode is attached using the flange 6. The first electrode, the inner conductor and the return conductor are mounted on the dielectric plate 7, which is a fragment of the vacuum chamber 8. The holes 9 in the dielectric plate serve to supply the working gas.

 The volume of the accelerating channel is limited by electrodes 1, conductor 4, and plate 7. After filling it with working gas, a high voltage is applied to electrode 1 by means of spark gap 3, which causes a gas breakdown in the interelectrode gap. As a result, a ring TPO is formed, which, under the action of electromagnetic forces, is compressed to the axis of the system in the same way as it happens in the well-known Z-pinch. Subsequently, the interelectrode gap becomes non-conductive due to the presence of crossed electric and magnetic fields in it, in which the residual plasma can drift only in the direction perpendicular to both the electric and magnetic fields, that is, to the axis of the system. Current along the inner conductor 4 begins to flow only after the TPO that is compressed to the axis reaches its surface. In this case, the initial SST is split and two SPS closing the electric circuit are formed, in which the currents are directed radially and opposite to each other. Accordingly, the electromagnetic forces acting on each of the SST are also oppositely directed. As a result, one SST accelerates toward the open end of the channel, as in the known plasma accelerator, and the other moves toward the end closed by the plate 7, and the other moves toward the end closed by the plate 7, performing a passive function of the conducting element of the current circuit.

Sources of information
1. Marshall I.Phys. Fluids, 1960, v. 3, N.1, p. 134.

 2. Grishin S. D. et al. Plasma accelerators. M. Engineering, 1983. p. 121, fig. 5.4 (prototype).

Claims (1)

 A plasma accelerator containing coaxially mounted electrodes made in the form of two hollow cylinders and connected to a high-voltage source of electric energy, a central conductor, forming together with the electrodes a coaxial accelerator channel with an initiating gas-discharge gap, characterized in that the electrodes are sequentially arranged along a central electrically insulated conductor with the gap between their ends, which serves as the initiating gas-discharge gap.