A modified version of the generalized performance model developed by Lafleur is used to interpret the low thrust performance measured for the CubeSat Ambipolar Thruster (CAT) in a previously reported thruster configuration. For partially magnetized ions the detachment criterion proposed by Lafleur, where detachment occurs when the local ion gyroradius equals the local plasma radius, is replaced with the turning point detachment criterion proposed by Little. The results from the original Lafleur model and the modified model are compared to indirect thrust measurements, and the plasma thrust predicted by the modified model matches the experimental data within errorbars. The modified model is used to investigate the change in performance due to variations in the design parameters and the operating conditions of the thruster. From this analysis the electron temperature is determined to be a critical parameter, and that at electron temperatures of ≤ 3 eV marginal improvement of ≤ 2% in performance over cold gas operation is obtained. The primary mechanisms to control the electron temperature are shown to be the source aspect ratio (R_s/L_s) and the propellant mass flow rate. To a lesser degree the detachment ion Mach number is shown to have an impact on the performance. The model also shows that the relatively low CAT thrust performance is due to a small aspect ratio of ~ 0.12 and a nominal operating mass flow rate that is an order of magnitude too high to get good performance (≥ 500μN). To improve the performance of CAT it is suggested that the aspect ratio be changed to ~ 1 and the operating propellant flow rate reduced to ~ 25% of the current nominal flow rate. A discussion on how to maximize performance of generalized magnetic nozzle thrusters is included.
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