Influence of size scaling and plasma-wall interaction on features of hall thruster microturbulence

Summary form only given. Turbulence at length scales on the order of the electron Debye length has been shown to be a possible contributor to anomalous electron transport in the Hall thruster. Simulations¹ and coherent Thomson scattering experiments² have identified an azimuthal instability of megahertz frequency and millimeter wavelength which is associated with increased electron current.Recent observations show that the instability is present in a range of thrusters, ranging in power from a few hundred watts to a few kilowatts. The mode amplitude, however, appears to depend on features such as the ratio of channel width to thruster diameter. Radial-azimuthal PIC simulations have also recently demonstrated the strong coupling between the instability and secondary electron emission from the walls3. The contribution of secondary electron emission to the electron current is influenced partly by plasma heating induced by the instability. Experimental investigations performed with highand low-emission wall materials reveal that the emission characteristics influence the fluctuation amplitude and localization of the instability. This work discusses recent results from experiments and PIC simulations showing the influence of such size scaling and wall interaction effects on observed microturbulence characteristics.