Mathematical modeling of low frequency oscillations of stationary plasma thruster

Summary form only given. The origin of the oscillations in the range 1-100 kHz which have been observed during the working of a stationary plasma thruster has not been well understood until now. Our purpose is first to clarify the nature of these oscillations and second to propose a new explanation using the concept of current instabilities proposed by Buneman. To reach this objective, a spectral study of the linear instabilities has been performed with a stationary quasi-neutral hybrid model. These computations show unambiguously a relationship between the nonlinear oscillations appearing in the transient simulation and the amplitude of the eigenvalues. Then, a simplified model has been derived which highlights the balance between the electric field and the ion current that is responsible for these oscillations. This study suggests controlling the current oscillation amplitude by modifying the magnetic field profile inside the SPT channel.