电弧等离子体折射率的理论计算

THEORETIC CALCULATION OF ARC PLASMA REFRACTIVE INDEX

从等离子体物理方程出发,推导出了折射率与电弧等离子体各种组分和温度之间的关系,并以氩电弧等离子体为例进行了实际的数值计算。这一关系的确立,为基于折射率效应的激光干涉法电弧等离子体诊断技术提供了理论基础,因此可以采用单波长激光干涉法(包括全息法)同时确定电弧等离子体的各种组分和温度,从而避免了采用双波长法时的缺点,这对发展电弧等离子体诊断及其加工技术有重要意义。计算结果表明,在波长给定时折射率是原子密度和电子密度的单值函数;温度小于6 000 K时,电子对折射率几乎没有什么影响,当温度高于17 000 K后,折射率则完全由电子决定。

According to plasma physical equations, the equation between the refractive index and the each components and temperature of arc plasma is deduced. Taking argon arc plasma as example, the refractive index has been calculated in varying temperature. The equation built provided a theoretic foundation for the diagnosing arc plasma by laser interferometry based refractive index effect. In this way, we can determine the arc plasma each of components and temperature through single-wavelength laser interferometry (included laser holographic interferometry) at the meantime, which can avoid many disadvantages of dual-wavelength method. The diagnosing arc plasma by single-wavelength laser interferometry plays an important role in developing technologies of arc plasma diagnosis and processing. The calculative result shows that refractive index is monotropic function of atomic density and electron density if wavelength is given; when temperature less than 6 000 K, electron has no effect on refractive index; When temperature more than 17 000 K, refractive index is completely determined by electron.