Theoretical and experimental studies of large scale modes in Hall thrusters and methods of their control
Romadanov, Ivan 1986-
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Partially-magnetized plasmas with magnetized electrons and weakly-magnetized ions in crossed electric and magnetic fields are common in the nature and industrial devices, such as magnetrons, MHD generators, electric propulsion (ion/Hall thrusters, helicon thrusters), and Penning discharges. Such plasmas are usually in a strongly non-equilibrium state, exhibiting a variety of turbulent fluctuations. These fluctuations are responsible for anomalous transport phenomena and large-scale plasma structures. This study investigates one of the most known and pervasive examples: rotating spokes and breathing modes, in Hall thrusters. Breathing mode is an m=0 mode (where m is the azimuthal mode number), propagating in the axial direction, and leading to strong oscillations of the discharge current, up to 100 % in amplitude. Spoke is an m=1,2,… mode, rotating in an azimuthal direction and is thought to be responsible for a large part of the anomalous current in a system. These large-scale perturbations can critically affect the performance of Hall thrusters, but the exact nature of these modes is unknown. Both types of oscillations are believed to be induced and strongly affected by the equilibrium electron current due to ExB drift, plasma density gradients, and ionization. This thesis is devoted to theoretical and experimental studies of spoke and breathing mode mechanisms, their coupling, and methods of their control.
DegreeDoctor of Philosophy (Ph.D.)
DepartmentPhysics and Engineering Physics
CommitteeKoustov, Alexandre; Xiao, Chijin; Bradley, Michael; Kasap, Safa
Copyright DateJanuary 2019