Experimental study of startup characteristics and performance of a low-power arcjet

A radiation-cooled low-power arcjet thruster is tested in order to study the startup characteristics andperformance with nitrogen and ammonia mixtures as the propellant in a vacuum with chamber pressures lower than 5 Pa. In the ignition tests, two different starter circuits, i.e., high-frequency and high-voltage pulse ignition techniques, are used to initiate the discharge. The results of the ignition tests show that arc current, electrode temperature, inlet pressure, and mole fraction of ammonia in the propellant have significant effects on arcjet startup characteristics. Experimental studies are also carried out to reveal the effects of different molar mixing ratios of nitrogen/ammonia mixtures on arcjet thruster performance. It is found that the important performance parameters of arcjet such as thrust, specific impulse, and thrust efficiency increase with an increased amount of ammonia in the propellant. The molar mixing ratio of the nitrogen/ammonia mixtures has significant effects on arcjet currentvoltage characteristics.