微波在液体火箭发动机真空羽流中的衰减

为研究液体火箭发动机真空羽流对微波的衰减作用，以某双组元液体火箭发动机为对象，使用热力计算程序对燃烧室内的电子数密度进行了计算，使用冻 结假设和有限化学反应速率假设两种情况对喷管内带电粒子的电离和再结合过程进行了模拟，并对羽流中带电粒子数密度和5~30GHz微波穿过羽流的衰减量进行了估算.研究结果显示:该发动机燃烧室和喷管出口的电子数密度量级分别为 1013~1014cm-3和1010~1011cm-3，K，Na等碱金属为主要电子释放剂，Cl-，OH-等基团为主要电子吸收剂；低频微波在羽流中衰减更严重，5GHz微波的衰减可达4.5dB；微波斜穿羽流的衰减通常大于横穿情况. 

Microwave attenuation in vacuum plume of the liquid-propellant rocket engine

The microwave attenuation in the vacuum plume of the liquid-propellant rocket engine was studied. Based on a sample of the bipropellant engine, the electron number densities in the chamber was calculated using a thermodynamic calculation code. The ionization and recombination processes in the nozzle were simulated under the assumption of frozen components or limited reaction rate. The electron number densities in the plume and the microwave attenuation of 5－30GHz were estimated. It is shown that the number densities are within the range of 1013-1014cm-3 and 1010-1011cm-3, respectively, for the chamber and the exit of the nozzle. The alkali metals, K and Na, are main contributors of electrons while Cl- and OH- are main electron absorber. The attenuation is more serious for the microwave of lower frequency and oblique path, as high as 4.5dB in case of 5 GHz.