HEAT LOSS REDUCTION AND PERFORMANCE IMPROVEMENT OF A DC ARCJET

本研究的目的是通过光学测量系统测量电弧柱到电极的热损失通量和等离子体的电子温度，研究直流电弧式引弧发动机的热损失机理，以改善直流引弧发动机的推进性能。为了测量弧柱电子温度分布，设计并制作了一种高分辨率光学测量系统，该系统采用了过去实验中使用的单色仪与新型的CCD相机相耦合的方法。结果表明，通过合理选择推进剂流量、放电电压和喷嘴形状等操作参数和几何设计参数，可以通过降低喷嘴喉部弧柱的电子温度和导热系数来降低流向阳极喷嘴的热损失通量。

The purpose of this research work is to investigate heat loss mechanisms in a DC arcjet by measuring heat loss flux from arc column to electrodes and electron temperature of the plasma with an optical measurement system and to improve thruster performance of the arcjet.Using an segmented anode nozzle of the arcjet, heat loss distributions at the anode surface were investigated by measuring the temperature rise of cooling waters. To measure electron temperature distributions of the arc column, a high-resolution optical measurement system was designed and fabricated with a new CCD camera coupled with a monochrometer which had been used in the past experiment. With these experimental devices, we could obtain the above distributions and the relationship between the heat loss flux and electron temperature.As a result, it was found that the heat loss flux to the anode nozzle can be reduced by lowering electron temperature and thermal conductivity of the arc column at the nozzle throat with a proper choice of operating and geometric design parameters such as propellant flow rate, discharge voltage, and nozzle shape.