Solid propellant pulsed plasma thruster driven by magnetic pulse compression circuit

摘要

In this study, a SPPT (Solid Propellant Pulsed Plasma Thruster) driven by a MPC (Magnetic Pulse Compression) pulse generator is presented. Electromagnetic SPPT is well-known and is one of the most simple structures for electric propulsion: it is very lightweight and reliable and its thrust force can be easily controlled by the pulse discharge characteristics. In this type of system propellants are supplied from ablation of the solid propellant by surface discharge; therefore, it is difficult to regulate the propellant supply and ensure efficient use. This causes low performance of PPT. To achieve efficient utilization of the propellant, a MPC pulse generator was used as the power source of the SPPT. The magnetic switch which was used in the MPC has a magnetic saturation characteristic. When the magnetic switch is unsaturated, discharge current is restricted by the high inductance of the magnetic switch, and propellants are fed and excited by surface discharge. Later, when the magnetic switch is saturated, high current flows through the plasma and it is accelerated by the Lorentz force. Here, a high di/dt converted the mechanism to acceleration, quickly. It was contributed to reduce the Late-Time Vaporization by low rising temperature. Also, the main discharge was formed including pre-spread plasma and it accelerates the plasma efficiently. The pulse discharge of the MPC also composes the igniter which does not require an external power supply. A co-axial electrode type MPC-SPPT was designed and operated to demonstrate the system. The igniter was put as the center electrode and driven with a MPC pulse discharge. The 18 J MPC with a thruster body has a 41.6 nF energy storage capacitor and less than 80 nH of parasitic inductance. The peak discharge current is 15 kA, and the thrust performances were evaluated by a thrust target. From experimental results the advantages and capabilities of a MPC-SPPT system are discussed.