2. Government Accession No. 4. Title and Subtitle 30-kW Ammonia Arc jet Te,:hnology

report summazizes the technical results of a 30-kW class ammonia-propellant arcjet technology proglam that extended over 3 1/2 years. Evaluation of previous arcjet thruster perfor_mnce, including materials analysis of used thruster components, led to the design of arL arcjet with improved performance and thermal characteristics. Tests of the new engine demonstrated that engine performance is relatively insensitive to cathode tip geometry. Other data suggested a maximum sustainable arc length for a given thruster configuration, beyond which the arc may reconfigure in a destructive manner. A flow controller calibration error was identified. This error caused previously reported values of specific impulse and thrust efficiency to be 20-percent higher than the real wLlues. Corrected arcjet performance data are given in the report Duration tests of 413 and 252 hours, and several tests i00 hours in duration, were performed. The cathode tip erosion rate increased with increasing arc current. Elimi-nation of power source ripple did not affect cathode tip whisker growth. Results of arcjet modeling, diagnostic development and mission analyses are also discussed. The 30-kW ammonia arcjet _y now be considered ready for development for a flight demon