Inductive energy storage driven vacuum arc thruster

A new type of vacuum arc thruster in combination with an innovative power processing unit (PPU) has been developed that promises to be a high efficiency (similar to15%), low mass (similar to100 g) propulsion system for micro- and nanosatellites. This thruster accelerates a plasma that consists almost exclusively of ions of the cathode material and has been operated with a wide variety of cathodes. The streaming velocity of the plasma exhaust varies with cathode material, from a low of 11 km/s for Ti up to 30 km/s for Al, with a corresponding range of specific impulse from 1100 s for Ta to 3000 s for Al. Initiation of the arc requires only a few hundred volts due to an innovative "triggerless" approach in which a conductive layer between the cathode and the anode produces the initial charge carriers needed for plasma production. The initial starting voltage spike as well as the energy to operate the vacuum arc are generated by a low mass (<300 g) inductive energy storage PPU which is controlled using +5 V level signals. The thrust-to-power ratio has been estimated to reach up to approximate to 20,mu N/W. The vacuum arc thruster was tested at the Jet Propulsion Laboratory using W as cathode material. Experimental results are within 65% of the estimated values. (C) 2002 American Institute of Physics.