Study and modeling of propellant ablation in coaxial ablative pulsed plasma thrusters

The influence of the main design parameters on the ablated mass bit (the mass ablated from the propellant in each discharge) of a coaxial ablative pulsed plasma thruster is analyzed in this paper. The analysis results show that the main influencing factor of the ablated mass bit in coaxial ablative pulsed plasma thrusters is the ablation energy from the arc. When the ablation energy is given, the shape and size of the propellant surface mainly affect the distribution of the ablated mass but have less influence on the ablated mass bit. Based on the analysis, a simple model that can be used to estimate the ablated mass bit of the coaxial ablative pulsed plasma thruster is established. To evaluate and complete the new model, a coaxial ablative pulsed plasma thruster is operated and tested under 10 different working conditions. The experimental results show that the ratio of the ablated mass bit to the absolute value integrals of the product of the electrode voltage and discharge current is approximately 0.38–0.49 μg/J. When the ratio is set to 0.44 μg/J, the maximum and average errors of the new model are 15.7% and 7.6%, respectively, for ablated mass bits under these 10 working conditions. The concept of the ablation direction is proposed in this paper. The experimental and simulation results show that the ablation direction has a great influence on the propellant surface profile change in coaxial ablative pulsed plasma thrusters, which also affects their performance and reliability.