Evaluation of Thrust Characteristics of 2 cm Class SF-MPD Thruster with Quasi-Steady-State Operation

Abstract

In order to understand the characteristics of the Self-field MPD thruster with a discharge chamber diameter of 2cm, a ground experiment system was constructed and the thrust characteristics were obtained. For the power supply system, a capacitor bank using an electric double-layer capacitor and IGBTs was adopted, and it was confirmed that rectangular discharge current pulses could be output at arbitrary times. In the operation check of the experimental system, the discharge current, discharge voltage, and ion saturation current remained constant during 2ms, confirming the quasi-steady operation of the small MPD thruster for 2ms. Thrust measurement experiments were conducted using argon as the propellant, and a thrust force of 0.9N was confirmed at a maximum discharge current of 2.2kA. The measured thrust was proportional to the square of the discharge current. Therefore, it was confirmed that electromagnetic acceleration was dominant. As the highest propulsive characteristics, a specific impulse of 1800s and a propulsive efficiency of 2.3% were confirmed.