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236 MEMS and Microstructures in Aerospace Applications

FIGURE 11.3 Erosion pattern of coaxial m-PPT. (Source: University of Illinois.)

TABLE 11.1
Performance Characteristics for Micro-PPT

500 sec
I sp
I-bit (if pulsed) 15 mN sec
Rep. rate (if pulsed) 2 Hz
Power 10 W
Thrust >30 mN
Thrust or power 10 mN/W
Impulse or prop. 5 Ns/g
Feed mechan. No
Current system mass 600 g
(include PPU, valve, tank, etc.)

11.2.2 VACUUM ARC THRUSTER
The need for a low-mass propulsion system motivated the development of the
vacuum arc thruster. 17–21 This device is essentially a pulsed plasma thruster that
uses conductive cathode materials as propellant. It requires an energy storage PPU
that takes 5–24 V from the bus and converts it into an adequate power pulse for the
thruster. It is a system well suited to provide small impulse bits ( 1 mN sec) at high
specific impulse, I sp (1000 to 3000 sec). Applications include positioning and drag-
makeup for small spacecraft that are power- and mass-limited satellites.

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