THEORETIC CALCULATION OF ARC PLASMA

 REFRACTIVE INDEX

Xue haitao  li huan  li junyue 

(Faculty of Materials Science and Engineening, tianjin university, Tianjin 300072)

liu jinhe

(Faculty of Materials Science and Engineening, northwestern polytechnical university, Xi’an 710072)

Abstract: 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.

Key words: Plasma diagnostic  Refractive index  Single-wavelength  Laser interferometry.

CLC No: TG403  O539

国家自然科学基金(59975068)和天津市自然科学基金(993602911)资助项目. Received 20030507, received in revised form 20040312