Numerical Simulation of HiPEP Ion Optics

The ffx code was used to investigate the lifetime and propellant throughput capability of the High Power Electric Propulsion (HiPEP) thruster ion optics as part of NASA’s Project Prometheus. Erosion predictions are presented as a function of beamlet current, accel grid voltage, and propellant utilization efficiency. These predictions were then compared to the lifetime goals of the thruster, and for nominal operating conditions, the ffx code indicates that the HiPEP thruster will have propellant throughput capability of 100 kg/kW and lifetimes in excess of 135 khrs. In addition to lifetime assessment, a detailed study was completed where grid design parameters were varied in a systematic manner to determine their effects on beamlet current limitations and electron backstreaming margins. The parameters that were varied included the net and total accelerating voltage, grid spacing, aperture center-to-center distance, accel grid thickness, screen grid thickness, discharge voltage, and accel grid aperture diameter.