Azimuthal micro-instability inside a wall-less hall thruster

Summary form only given. In a Hall Thruster (HT), a discharge is ignited inside an annular ceramic chamber between an anode situated at the rear of the device and an electron-emitting hollow cathode downstream of the channel. Xenon gas propellant is injected through the anode plane. A magnetic field is created using internal and external coils to achieve a quasi-radial magnetic field profile. A discharge voltage applied between the anode and the cathode is responsible for the acceleration of the ions and the engine thrust. Nevertheless, a fraction of the energetic ions bombards the ceramic walls, resulting in erosion that reduces the thruster lifetime¹.An alternative architecture has recently been tested for a low power HT. In this new configuration, the anode is now a ring very close to the channel exhaust. Magnetic coils have been replaced by permanent magnets. This new HT configuration has been named the Wall-Less HT (WLHT) because ionization and acceleration occur outside the channel2. Because in such a configuration the plasma-wall interactions are strongly reduced, the WLHT may offer the opportunity of an increased lifetime with performance levels similar to those of a conventional HT. We have developed fully Particle-In-Cell (PIC) Monte Carlo Collisions (MCC) model of the WLHT. The two-dimensional PIC MCC model describes the azimuthal and axial directions3. A hybrid parallel programming technique that combines OpenMP and MPI on 16 processors is employed to shorten computation time to a few days. Simulations reveal the presence of a micro-instability that participates to the cross-B field electron transport.