Micro Pulsed Plasma Thrusters
Pulsed Plasma Thrusters (PPT) are an electromagnetic propulsion device. They use the electrical energy of a capacitor to form a high current arc discharge across a solid propellant surface (typically Teflon). The energy of the arc ablates the surface of the propellant creating an ionized gas. This ionized gas is accelerated out of the channel at high velocities through electromagnetic forces creating thrust. The electromagnetic force is called the Lorentz force, which describes the interaction between the current vector and the self induced magnetic field vector of the arc discharge. A PPT is a pulsed device that is capable of very precise impulse bits. This capability allows for low jitter precision maneuvers of small satellites that can not be match by traditional ACS systems.
Busek began commercial development of a micro version of a PPT in 2002 based on technology originally developed at AFRL. A 3-axis version of the MicroPPT (μPPT) will be flying on the US Air Force Academy’s FalconSat-3 mission in 2006 under the acronym MPACS. MPACS stands for Micro Propulsion Attitude Control System. Four clusters of MPACS thrusters will be flown for propulsive ACS demonstration. Each cluster is a stand-alone unit containing all necessary electronics, requiring only power and commands from the spacecraft.
Download the MicroPPT Sheet (4 MB PDF).
MPACS Performance
Discharge Energy: 1.96 Joules
Impulse Bit (avg): 80 μN-sec
Specific Impulse (avg): 827 sec
Propellant Consumption: 19.7 μg/pulse
Efficiency (avg): 16 %
Specific Thrust (avg): 40.8 μN/W
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