Pulsed plasma thruster

Pulsed plasma thrusters or pulsed magneto- plasma- dynamic thrusters (English Pulsed Plasma Thruster, PPT), in German-speaking countries as a non-stationary magneto- plasma- dynamic drives ( IMPD ) is known, belong to the electric space propulsion and rail control are installed satellite mostly used for position and. Due to their function they belong to the group of electromagnetic actuators.

PPT were first used in 1964 on the Soviet space probe Zond 2 successfully and can thus be regarded as the oldest electric space propulsion in space. Since then, they have been used several times for satellite missions, especially in the U.S., but also in Japan and China.

Construction

An IMPD engine consists of four major components:

In the past, both parallel and coaxial electrode configurations were examined. In both cases the fuel supplied between the electrodes. For most developments PTFE is used, but alternative fuels such as Water are investigated.

Principle of operation

The capacitor used will charge to an operating voltage (up to several kV). This mixture is ignited by igniter. Here, the resonant circuit consisting of capacitor closed, electrodes and fuel and it forms an arc discharge along the surface of the fuel. Due to the high discharge current of several kA part of the fuel is ablated, dissociated and ionized. In this case, charge carriers are formed between the electrodes. The time varying discharge current generates a strong magnetic field. Through interaction of this field with the charge carriers leads to an acceleration by the Lorentz force. The charge carriers are thus accelerated from the electrode gap, and generate thrust. The thereby achieved speeds of the carriers are in the range of several 10 km / s Since the energy of the capacitor is limited, the vibration sound in the circuit quickly, so that after some 10-20 microseconds collapse of the arc and of the push pulse has ended. Typical pulses are reached in some 100 μNs.

Technical realizations

PPT among others in Germany studied at the Institute of Space Systems ( IRS) at the University of Stuttgart and developed. There should serve two missions as technology demonstrators for electrical space propulsion systems as part of the Stuttgart small satellite program - Satellite Perseus and Lunar Mission BW1.

Research and development of PPT world focuses mainly on Russia, the U.S., Europe, Japan and China, but also developments in South Korea, Argentina, Iran and Turkey were observed. In addition to Zond 2 PPT were used successfully on several other satellite missions.