Operating Characteristics of Low Power Arcjets for Space Propulsion

This paper描述exploratory development of a low power arcjet for space propulsion such asnorth-south station keeping for geosynchronous satellites. Three kinds of arcjets （water cooled）arcjet,two-dimensional visible arcjet and radiation cooled arcjet) has been design and tested with n_2h_2 and mixture of n_2 + h_2 simulating hydrazine decomposion products at power levels from 0.5 to3kw . The focus of The present research effort is to develop a stable arcjet thruster with highthrust performance at the low mass flow rate and low discharge current level. In the tests ofarcjets,following results were obtained.(1) the large amount of electrode erosion occurs at theA double pulse trigger method是proposed as A softer starting procedure.(2) The preferredoperating conditions and thrust performance are as follows: Propellant n_2 + 2h_2 (mixed gas)；arc current 16a；mass flow rate 30mg /s；total thrust 145 mN；specific impulse 494 sec；thrust efficiency 31.2% .(3) heat input to The cathode is high as 8% of The input power and这是removed by regenerative cooling of the propellant. In additionthe arc efficiency is 85% .(4) From the calculation，the frozen flow loss is 40- 50% of the input power. the preferred opening angle of the nozzle seemsto be about 40 from the standpoint of the arc stability and thrust performance

This paper describes exploratory development of a low-power arcjet for space propulsion such as north-south station keeping for geosynchronous satellites. Three kinds of arcjets ( water cooled arcjet, two-dimensional visible arcjet and radiation cooled arcjet) has been designed and tested with N_2, H_2 and mixture of N_2+H_2 simulating hydrazine decomposion products at power levels from 0.5 to 3kW. The focus of the present research effort is to develop a stable arcjet thruster with high thrust performance at the low mass flow rate and low discharge current level. In the tests of arcjets, the following results were obtained.(1) The large amount of electrode erosion occurs at the start-up. A double pulse trigger method is proposed as a softer starting procedure.(2) The preferred operating conditions and thrust performance are as follows: Propellant N_2+2H_2, ( mixed gas ); arc current 16 A; mass flow rate 30 mg/s; total thrust 145 mN; specific impulse 494 sec; thrust efficiency 31.2 %.(3) The heat input to the cathode is as high as 8 % of the input power and is removed by regenerative cooling of the propellant. In addition, the arc efficiency is 85 % .(4) From the calculation, the frozen flow loss is 40-50 % of the input power. The preferred opening angle of the nozzle seems to be about 40゜ from the standpoint of the arc stability and thrust performance.