Plasma-Sheath Instability in Hall Thrusters Due to Periodic Modulation of the Energy of Secondary Electrons in Cyclotron Motion

Raitses, D. Sydorenko and A. Smolyakov I. Kaganovich and Y.

Princeton University. Plasma Physics Laboratory.

关键词: Thrusters Hall Thrusters;    Magnetic Fields;    70 Plasma Physics And Fusion Technology;    Modulation;    Cyclotrons;   

RP-ID  :  PPPL-4310
RP-ID  :  DE-ACO2-76CHO3073
RP-ID  :  959391

美国|英语

来源: UNT Digital Library

【 摘 要 】

Particle-in-cell simulation of Hall thruster plasmas reveals a plasma-sheath instability manifesting itself as a rearrangement of the plasma sheath near the thruster channel walls accompanied by a sudden change of many discharge parameters. The instability develops when the sheath current as a function of the sheath voltage is in the negative conductivity regime. The major part of the sheath current is produced by beams of secondary electrons counter-streaming between the walls. The negative conductivity is the result of nonlinear dependence of beam-induced secondary electron emission on the plasma potential. The intensity of such emission is defined by the beam energy. The energy of the beam in crossed axial electric and radial magnetic fields is a quasi-periodical function of the phase of cyclotron rotation, which depends on the radial profile of the potential and the thruster channel width. There is a discrete set of stability intervals determined by the final phase of the cyclotron rotation of secondary electrons. As a result, a small variation of the thruster channel width may result in abrupt changes of plasma parameters if the plasma state jumps from one stability interval to another.