Measurement of sheath electric field in electronegative plasm as by laser-induced fluorescence-dip spectroscopy

该项目的目的是开发一种用于测量等离子体电场的灵敏诊断技术。该方法是一种激光斯塔克光谱法。采用激光诱导荧光光谱法对氩离子进行了电场测量，包括对电负性等离子体的测量。我们测量了氩高里德伯态在定义电场中的斯塔克光谱，并通过比较等离子体中观察到的光谱与定义电场中观察到的参考光谱来确定等离子体中的电场。我们实现了3V/cm的灵敏检测限，这是世界上最高的灵敏度。我们在电感耦合等离子体源中进行了电场测量。我们测量了插入等离子体中的金属电极前鞘层区域的电场分布。由于灵敏的检测限，我们成功地测量了鞘前区域的电场，在那里我们观察到均匀的电场，由于微电场。我们在Ar/SF_6电负性等离子体中重复了电场测量。首次发现了负电性等离子体鞘层电场具有多级结构。

The purpose of this project is the development of a sensitive diagnostic technique for measuring electric fields in plasmas. The method is a kind of laser Stark spectroscopy. We adopted laser-induced fluorescence-dip spectroscopy to argon, in order to carry out the electric field measurement in various plasmas including electronegative plasmas. We measured Stark spectra of argon high Rydberg states in well-defined electric fields, and the electric fields in plasmas were determined by comparing the spectra observed in plasmas with the reference spectra observed in well-defined electric fields. We achieved sensitive detection limit of 3 V/cm, which is the champion sensitivity in the world. We carried out the electric field measurement in an inductively-coupled plasma source. We measured the distribution of electric field in the sheath region in front of a metal electrode inserted in the plasma. Owing to the sensitive detection limit, we succeeded in measuring the electric field in the presheath region, where we observed uniform electric field due to the inicrofield. We repeated the electric field measurement in Ar/SF_6 electronegative plasmas. We have found for the first time that the sheath electric field of electronegative plasmas has multistage structure.