Effect of magnetic field lines on plasma uniformity for an axial ring cusp hybrid discharge chamber using improved 3D hybrid PIC/MCC method

This paper investigates the influence of magnetic field lines and the effects of electron emission positions, particularly annular emission, on the plasma uniformity of an Axial Ring Cusp Hybrid (ARCH) discharge chamber integrated with a hollow cathode, using an improved three-dimensional (3D) hybrid Particle-In-Cell/Monte Carlo Collision (PIC/MCC) numerical model. The model uses an enhanced Immersed Finite Element (IFE) method to calculate the plasma distribution with the sheath taken into account. The results show that in ARCH thrusters, as the emission position approaches the screen grid, the mean primary electron density decreases, and the uniformity near the exit plane deteriorates; therefore, it is essential to minimize contact between the hollow cathode and the plasma to maintain optimal performance. In the simulated six types of magnetic field distribution, with the increase of the arch height of the arch magnetic field line, the mean primary electron density in the discharge chamber increases and decreases rapidly with the increase of the arch angle after the arch height reaches the peak. It is found that there is an optimal magnetic field when the arch height is the same as the height of the discharge chamber and the arch angle is between 56.3 ∘ and 63.4 ∘ . In addition, the annular emission in discharge performance are explored, and it is revealed that avoiding the axial center emission of primary electrons significantly improves the plasma uniformity near the exit plane.