Oscillations of the Hall current in a Hall thruster with an anode layer

Abstract

Burning of an intense discharge in crossed electrical and magnetic fields in a Hall electrojet engine (Hall thruster) is considered. An engine of this type is an azimuthally symmetric device in which the discharge burns in an annular channel between the poles of the magnetic circuit. The anode is usually made in the form of a cavity through which the working gas is supplied (thruster with anode layer, TAL) or in the form of a planar ring mounted in a dielectric channel in a weak magnetic field (stationary plasma thruster, SPT), and the role of the cathode is played by the plasma surrounding the engine. The electrons trapped in the magnetic field between the poles of the magnetic circuit oscillate in the electric field between the anodic and cathodic regions of the discharge, forming the Hall current closed in the azimuthal direction. It is known from practice that discharge of this type is always nonstationary and the main self-sustained oscillations are excited on the atomic time-of-flight frequency (“accelerative” regime). In addition, there exists a region of parameters in which the self-sustained oscillations become stochastic and the discharge current increases sharply (“stochastic” regime). This work is devoted to the induction measurements of the oscillations of the Hall current arising in various regimes of operation.