ARC-JET THRUSTOR FOR SPACE PROPULSION

Abstract : The arc-jet thrustor represents an engine for potential space applications requiring a specific impulse in the range from 1000 to 2000 seconds. As such it was originally thought that missions for the engine would fit somewhere between those suitable for the high thrust chemical and the very low thrustion propulsion systems. The considerable effort expended to develop the arc thrustor has resulted in operation in the power range from 1 to 200 kilowatts, at specific impulse levels between 1000 and 2000 seconds, and for continuous running as long as 500 hours with overall efficiency up to 55 percent. Progress has been made on many of the early operating problems such as electrode-erosion, nozzle-cooling, and propellant-feed systems. In addition, theories have been advanced to explain, at least partially, the electric-arc operation In substance then, the thermal arc-jet thrustor is now fairly well developed. Because of several factors unrelated to impulse and efficiency levels, however, the mission application of the arc thrustor is somewhat doubtful at the present time. These factors, for the larger arc-jet thrustor, include biological shielding, hardware availability, excessive electric generator weight, and reliability, for example.