Spontaneous oscillations in a Hall thruster

Low frequency oscillations in a stationary plasma thruster (SPT) have been studied using optical diagnostics and numerical models. The regime of low f requency, large amplitude current oscillations has been especially investig ated. The current oscillations are associated with strong oscillations of t he light emitted by the plasma in that region. A quasi-neutral hybrid model of the plasma can reproduce these plasma oscillations and suggests that th ey are due to an ionization instability in the exhaust region associated wi th the depletion of neutral atoms by electron impact ionization.