外加磁场微波等离子体喷流对平面电磁波衰减的实验研究

Experimental study on the effect of applied magnetic field on plane wave attenuation by microwave plasma plume

采用空间透射波测量方法,实验研究透波密闭石英玻璃容器内等离子体喷流对垂直和水平极化电磁波的衰减,在有和无外加磁场条件下分析实验参数对等离子吸波效应的影响,分析等离子体的吸波机理.实验结果表明在非磁和本实验条件下,平面电磁波在等离子体中的衰减机理为碰撞吸收;在有磁和本实验条件下,平面电磁波在磁等离子体中的衰减机理同样为碰撞吸收,但是外加磁场的存在有限地改善了等离子体的吸波效应.为了使磁等离子体最有效地吸收电磁波,应该提高磁场感应强度,把高频混杂频率提高到测试微波频率范围内,或降低微波测试频率至本实验中的高混杂频率附近.

The effect of applied magnetic field on the plane wave attenuation by microwave plasma plume inside a closed and evacuated quartz vessel is studied though spatially propagating wave method. The objective is to analyze how the operating parameters affect the wave attenuation in plasma and to find the mechanism which controls the interaction between plasma and plane wave. The experimental results show that under the present experimenal condition and in the cases without and with applied field, collisions are the reason leading to plane wave attenuation in the plasma. Plasma resonance absorption and upper hybrid resonant absorption mechanisms can not be found. To increase the plane wave attenuation in magnetized plasma, magnetic flux density should be set to make the wave test frequency and upper hybrid frequency identical.