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

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