2D Particle-in-cell simulations of the electron-cyclotron instability and associated anomalous transport in Hall-effect thrusters
Résumé
In this work we study the electron-cyclotron instability in Hall-effect thrusters (HETs) using a 2D electrostatic particle-in-cell (PIC) simulation. The simulation is configured with a Cartesian coordinate system where the magnetic field, *B0*, is aligned along the x-axis (*radial direction*, including absorbing walls), a constant applied electric field, *E0*, along the z-axis (perpendicular to the simulation plane), and the ExB direction along the y-axis (*Theta direction*, which uses periodic boundaries). Although electron transport can be well described by classical electron-neutral collision theory for low plasma densities, at sufficiently high densities (typical of those measured in HETs), a strong instability can be observed that enhances the electron mobility, even in the absence of electron-neutral collisions. The instatbility generates high frequency (of the order of MHz) and short wavelength (of the order of mm) fluctuations in both the electric field and charged particle densities, and we investigate the correlation between these fluctuations and the role they play in anomalous electron transport; work which compliments previous 1D simulations. Wall effects on the instability are studied here in the case where the plasma is self-consistently heated by the instability. Since the instability does not reach saturation in an infinitely long 2D system, saturation is achieved through the implementation of a finite axial length that models convection in the *E0* direction (i.e. perpendicular to the simulation plane).