Abstract
An electric discharge is implemented in a gas at the end of a non-conducting cylinder between the central electrode coaxial with the cylinder and the ring electrode located on the cylinder surface near the cylinder end. The cylinder axis coincides with the axis of a magnetic coil winded on the lateral cylinder surface. The shape of the gas discharge and distribution of thermal emission centers on the surface of the ring electrode when varying the discharge current and the magnetic induction are investigated. In addition, the dynamics of the gas discharge in a solenoidal magnetic field at the outlet of a supersonic conical nozzle is also investigated. In this case, the discharge is ignited between the nozzle sidewall and a rod located along the nozzle axis. I. Introduction Within the cycle of the works conducted at the Ioffe Institute when tackling the problem of magnetohydrodynamic control of a supersonic flow as an object under study we employed a model with an electromagnetic facility in a supersonic nitrogen flow. This model is a sharp 60° cone mated with a cylinder of 34 mm in diameter at the surface of which a solenoid is located. One of the ends of the solenoid is connected with a metal ring electrode located at the model surface at the place of conjugation of the cone with the cylinder. The other solenoid end is connected to one of the terminals of an external pulsed voltage source. The other source terminal is connected with the central electrode shaping the cone vertex. In the gap between the central and ring electrodes an electric discharge is ignited which is sustained by the external voltage source. Thus, the gas discharge was implemented in the solenoidal magnetic field near the conical surface of the model. In work [1] an appreciable dependence of the dynamics of such a discharge on the polarity of connection of the electromagnetic facility to the voltage source was detected, in particular, when changing the connection polarity the frequency of rotation of the discharge changed by two times. To elucidate the reasons for such a dependence an experimental setup was designed and constructed and additional investigations were conducted [2] that showed that the discharge motion is governed by the dynamics of the cathode spot over the surface of the ring electrode and by action of the ponderomotive force. Interference between these two physical processes may lead to various effects, for example, to redistribution of the heat load over the model surface, which is noted by the authors of [2]. The present work is devoted to the further study of possibilities of employment of magnetohydrodynamic effects in gasdynamic experiments, in particular, to investigation into dynamics of the gas discharge in the soleniadal magnetic field under the conditions when an appreciable influence is exerted by physical processes at the electrode surface. First of all we keep in mind so-called anomalous motion of the cathode spot which consists in capability of the cathode spot to move in a solenoidal magnetic field in the direction opposite to the action of the ponderomotive force [3-5]. II. Experimental setup
Published Version
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