Abstract
Microfabrication of a 3 x 3 micro-plasmajet array with ultra-violet lasers and their thrust performance tests were conducted for nozzle elements with exit height of 0.5 mm and length of 0.5 mm. Stable discharge and operational conditions were confirmed for the 3 x 3 micro-plasmajet array thruster. To evaluate thrust characteristics of the arrayed plasmajet, thrust characteristics of the thruster were compared with those of the micro-single-nozzle plasmajet. It was shown that the thrust and specific impulse of the micro-plasmajet array were higher than those of the micro-single-nozzle plasmajet due to the multi-jet effect. The typical values of the thrust, specific impulse and thrust efficiency averaged per nozzle element of the microplasmajet array thruster operated at 6.2 W with 1.46 mg/sec of nitrogen gas propellant mass flow per nozzle element were 1.13 mN, 79 sec, and 24%, respectively. In addition, observation of the micro-nozzle discharges was conducted. To improve thrust performances and to achieve uniform discharges over all electrode elements, a new thruster with extended nozzle structure for which each electrode element was electrically isolated from nearby elements was developed. The typical values of the thrust and specific impulse of the multi-nozzle array thruster with 36 nozzle elements operated with 11 mg/sec of nitrogen gas propellant mass flow were 6 mN and 60 sec, respectively.
