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敏感的诊断技术，用于测量等离子体中的电场。该方法是一种激光斯塔克光谱法。我们采用激光诱导荧光浸谱法对氩气进行了包括电负性等离子体在内的各种等离子体中的电场测量。我们在明确的电场中测量了氩气高里德堡态的Stark光谱，并将等离子体中观测到的光谱与明确的电场中观测到的参考光谱进行了比较，确定了等离子体中的电场。灵敏度检测限达到3v /cm，灵敏度世界第一。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的金属电极前鞘层区域的电场分布。由于敏感的检测极限，我们成功地测量了鞘前区域的电场，由于显微场的作用，我们观察到均匀的电场。我们在Ar/SF_6电负性等离子体中重复了电场测量。首次发现电负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.