The problem of the anomalous electron transport in crossed electric and magnetic fields in Hall plasma thrusters is investigated. Two mechanisms of turbulent transport are considered: a gradient-drift mechanism and a resistive one. A strong connection between these mechanisms and the corresponding instabilities is established. Our analysis shows that the gradient-drift transport prevails over the resistive one in the most turbulent domain of the channel. The gradient-drift transport organizes plasma in such a way to minimize the increment of the corresponding instability. This allows one to avoid explicit calculations of the fluctuation intensity while modeling transport phenomena. The modification of the dispersion relation for the gradient-drift instability, offered by Frias et al. (Phys. Plasmas, 19 (2012) 072112) to account for the current-free (vacuum) nature of a two-dimensional magnetic field, is discussed.

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According to present knowledge, countless numerical simulations of the discharge plasma in Hall thrusters were conducted. However, on the one hand, adequate two-dimensional (2D) models require a lot of time to carry out numerical research of the breathing mode oscillations or the discharge structure. On the other hand, existing one-dimensional (1D) models are usually too simplistic and do not take into consideration such important phenomena as neutral-wall collisions, magnetic field induced by Hall current and double, secondary, and stepwise ionizations together. In this paper a one-dimensional with three-dimensional velocity space (1D3V) hybrid-PIC model is presented. The model is able to incorporate all the phenomena mentioned above. A new method of neutral-wall collisions simulation in described space was developed and validated. Simulation results obtained for KM-88 and KM-60 thrusters are in a good agreement with experimental data. The Bohm collision coefficient was the same for both thrusters. Neutral-wall collisions, doubly charged ions, and induced magnetic field were proved to stabilize the breathing mode oscillations in a Hall thruster under some circumstances.

Hall-effect thrusters (HETs) are widely used for modern near-earth spacecraft propulsion and are vital for future deep-space missions. Methods of modeling HETs are developing rapidly. However, such methods are not yet precise enough and cannot reliably predict the parameters of a newly designed thruster, mostly due to the enormous computational cost of a HET plasma simulation. Another approach is to use scaling techniques based on available experimental