Characterization of high frequency oscillations in a small Hall-type thruster

The linear theory for plasma stability in a Hall-type thruster shows that high frequency oscillations are generated inside the thruster. These oscillations generate waves propagating along the channel. The frequencies depend on the value of different discharge parameters and the direction of propagation depends on the studied region. Here, two approaches will be proposed according to the value of the radial magnetic field and the sign of its gradient. An experimental detection performed outside the channel shows agreement between the models and the experiments. These waves appear as being "quasilongitudinal'' inside the channel and azimuthal outside the channel. (C) 1999 American Institute of Physics. [S1070-664X(99)00101-9].