Optimization of Hall thruster magnetic field topography
The improvement of the performance and component lifetime of a closed drift Hall thruster, as well as a decrease of plume divergence and plasma-spacecraft interaction is a goal of many research efforts at the University of Michigan. A three-dimensional magnetostatic code, Magnet 6 by Infolytica, was utilized in an effort to ascertain possible improvements to the Plasmadynamics and Electric Propulsion Laboratory 5 kW class P5 Hall thruster. The magnetic field topography was measured for the P5 thruster at a 1.6 kW operating condition where the coil currents were 2 A for the outer coils and 3 A for the inner coil. The measurements were then compared to the field topography predicted from the 3D code to verify the accuracy of the simulation. Next, several variations of the magnetic field circuit for the P5, which included coil size, pole piece shape and position, and operating currents were investigated using the 3D magnetic field code. The simulations focused on strengthening the radial magnetic field while decreasing the axial field and lessening the magnetic fringe effects at the exit plane to decrease divergence of the plasma plume. Modifications to the P5 thruster were made to experimentally verify the results of the numerical simulations. The magnetic field topography, plume divergence, and the performance characteristics of the thruster were determined and compared to existing data taken before the magnetic field was optimized.
