低气压闭式等离子体放电实验及光谱诊断

闭式等离子体可以克服等离子体隐身技术在开放环境中等离子体难以维持及能耗过大的问题。针对等离子体隐身应用，设计了一种封闭式的等离子体发生装置，选用微秒脉冲电源，以氩气为工质气体，在低气压环境下进行了放电实验。采用发射光谱法，测量了密闭腔体内部厚度方向上的Ar谱线强度，并将碰撞-辐射模型用于分析等离子体参数的分布规律。当放电参数确定时，给定电子温度和电子密度，可通过碰撞-辐射模型计算得到2p能级上的布居分布比值，将其与从光谱数据中得到的布居分布比值进行比较，当差异值最小时，即可确定相应的等离子体参数。通过对电子温度在1～5 eV范围内的2p9和2p1能级布居分布比值进行计算，分析了碰撞-辐射模型计算可能存在的误差。实验结果表明，在厚度方向上，封闭式腔体中的等离子体电子密度达到1011 cm-3量级且呈一定的梯度分布，但变化幅度不大，其分布情况有利于等离子体隐身技术的应用。

Experimental Study on Closed Plasma Discharging under Low Pressure and Spectroscopic Diagnosis

Closed plasma can overcome difficulties of maintaining plasma and excessive energy consumption in open environment. For plasma stealth technology, a closed plasma generator was designed. Using microsecond pulse generator and argon as working gas, discharge experiments were carried out under low pressure environment. The emission spectrum of Ar at different position in discharge chamber was measured. By using collisional-radiative modal(CRM), the distribution of plasma parameters was studied. At a given electron temperature and density with specified discharge parameters, corresponding population distribution could be obtained by CRM. By comparing the line ratio of argon 2p levels acquired from CRM with the line ratio from spectrum measured, the plasma parameters were confirmed after obtaining the minimum difference value. Using the line ratio of argon 2p9 to 2p1 from CRM while the range of electron density was 1~5 eV, the calculating error was analyzed. The results reveal that, the electron density of the closed plasma reaches a magnitude of 1011 cm-3 and shows a gradient distribution with small variational amplitude, and the distribution is beneficial to the application of plasma stealth.