Abstract
The JIEDI (JAXA's Ion Engine Development Initiative) tool was developed to assess the ion acceleration grid erosion of an ion thruster. The validation and the sensitivity analysis of the input parameters of the JIEDI tool are conducted in this paper. We compare the simulation results of the JIEDI tool and show that it successfully reproduces the full lifetime test of the μ10 prototype model. Through sensitivity analysis, we found that the sticking factor (the ratio of sputtered materials sticking onto a grid surface to sputtered materials hitting the grid surface) is the most sensitive input parameter when estimating the accelerator grid erosion and electron backstreaming time. The accelerator grid mass loss was 189% larger for a sticking factor of 0 compared to that determined for a sticking factor of 0.78. For the worst case scenario of grid erosion (without re-deposition (sticking factor = 0)), the uncertainty in the neutral mass flow rate through the grid holes is important when estimating the accelerator grid erosion. A 25% change in the neutral mass flow rate caused by a 6% change in the propellant utilization efficiency, corresponds to about a 20% change in the accelerator grid mass loss as well as the increasing rate of minimum potential on the axis. In contrast to the accelerator grid erosion, the uncertainties in the discharge voltage and grid gap (that affect the trajectory of the mainstream ions), are important when estimating decelerator grid erosion. A 40% change in the discharge voltage corresponds to about a 90% change in the decelerator grid mass loss.
