2D Particle-In-Cell simulations of the electron-cyclotron instability and associated anomalous transport in Hall-Effect Thrusters.*

This work studies the electron-cyclotron instability in Hall-Effect Thrusters (HETs) using a 2D Particle-In-Cell (PIC) simulation. The simulation is configured with a Cartesian coordinate system where a magnetic field, B$_{\mathrm{\mathbf{0}}}$, is aligned along the X-axis (radial direction, including absorbing walls), a constant electric field, E$_{\mathrm{\mathbf{0}}}$, along the Z-axis (axial direction, perpendicular to simulation plane), and the E$_{\mathrm{\mathbf{0}}}$xB$_{\mathrm{\mathbf{0}}}$ direction along the Y-axis (O direction, with periodic boundaries). Although for low plasma densities classical electron-neutral collisions theory describes well electron transport, at sufficiently high densities (as measured in HETs) a strong instability can be observed that enhances the electron mobility, even in the absence of collisions. The instability generates high frequency (\textasciitilde MHz) and short wavelength (\textasciitilde mm) fluctuations in both the electric field and charged particle densities. We investigate the correlation between these fluctuations and their role with anomalous electron transport; complementing previous 1D simulations. Plasma is self-consistently heated by the instability, but since the latter does not reach saturation in an infinitely long 2D system, saturation is achieved through implementation of a finite axial length that models convection in E$_{\mathrm{\mathbf{0}}}$ direction.