ICP反应室或ICP质谱仪不同,ICP在用于衰减微波时,其腔体采用全密封石英结构,同时缺少静电屏蔽、金属衬底和磁场约束等条件,研究其内部电子密度等参数的分布对于等离子体局部隐身技术具有重要意义.利用光谱分析法,对两种典型ICP源(螺旋型和盘香型)在密闭石英立方体腔内H模式下稳定放电的电子密度分布展开了对比试验研究.使用Ar离子谱中476.45 nm谱线相对光谱强度变化研究了不同型ICP源的E—H模式跳变和功率耦合效率,通过非H谱线(Ar)的Stark展宽法,诊断了两种源的天线垂直平面上的二维电子密度分布.实验发现ICP在H模下的电子密度分布受交变磁场产生的趋肤电流影响较大,趋肤深度随着放电功率的增大而减小,同时主等离子体区域体积缩小、电子密度增加,在天线的垂直面上,螺旋型源ICP电子密度呈中心轴对称型分布,盘香型源ICP呈双峰型分布.功率耦合效率受源天线形状及其容性耦合效应影响较大,光谱相对强度显示螺旋型源的功率耦合效率低于盘香型源.通过该实验方法,可以在石英立方腔体内得到最高电子密度范围为1.4×1017～2.5×1017 m-3的螺旋型ICP源和范围1.8×1017～3.0×1017 m-3的盘香型ICP源.

In the present paper,the spectrum analytic method was used to comparatively study the ICP electron density distribution through two typical ICP sources(spiral-type and planar-type) in closed quartz chamber.The E-H mode transition of inductively coupled plasma and power coupling efficiency were researched through the change in the relative intensity of argon ion spectral line(476.45 nm).Electron density distribution on the antennas-vertical plane of different ICP source was calculated through non-hydrogen-like Stark broadening of spectral line method.The test results show that the ICP electronic density distribution in H-mode discharge is significantly impacted by skin current of alternating magnetic field.The skin depth decreases with the increase in discharge power.Meanwhile,the bulk of the main plasma narrows and electron density increases.On the vertical plane of the antenna,electron density distribution presents center-symmetry by spiral-ICP source and bimodal by planar-ICP source.The power coupling efficiency is directly affected by source antenna shape and capacitive coupling effect.The relative intensity of the argon spectrum shows that the power coupling efficiency of spiral-type source is lower than that of planar-type source.The proposed experimental method provides a way to obtain a plasma source in closed quartz cube chamber with the highest electron density ranging from 1.4×1017 to 2.5×1017 m-3(spiral-ICP source) and 1.8×1017 to 3.0×1017 m-3(planar-ICP source).