Identification of plasma fluctuations and energy flow in hall thruster

In order to increase the thrust to power ratio in the Hall thruster,decrease in power consumption is a good strategy, and for this,suppression of electron transport toward the anode is crucial. Electron transport can be suppressed by increasing the magnetic field strength in the acceleration channel up to critical magnetic field strength. A sudden increase in electron transport across the magnetic field beyond critical value, however, can shift the system from the classical electron diffusion regime to anomalous electron diffusion. A wide variety of theories has been developed to describe anomalous electron transport in Hall thrusters, but the problem remains unresolved. As a first step to understanding anomalous electron transport, the nature of instabilities observed in Hall thrusters and the relationship between anomalous transport and these oscillations should be investigated. Therefore, we observed plasma instabilities inside the acceleration channel of a Hall thruster using a 76 GHz microwave interferometer, which is a non-intrusive measurement technique and it offers wide bandwidth up to a few MHz. The electron number densities in four different azimuthal position were measured. The phase difference is almost constant, about zero in the 10 kHz range oscillation. However, the 100 kHz oscillation, on the other hand, the phase difference in the 100 kHz range is not constant, this result shows that the 100 kHz range oscillation is not propagatinin the azimuthal direction.