プラズマ中の電界のレーザー分光法による新しい計測法に関する研究

概要

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In recent years， laser spectroscopic methods using laser-induced fluorescence（LIF）techniques resulting from a collisional redistribution of the excited atom population have been developed to measure the electric field in glow discharges． This reliance on collisions means that it is difficult to measure electric fields in low pressure discharges， in which this collisional redistribution is very inefficient． However， many plasma processing applications require low gas pressure， and so measurement methods that can be applied in low pressure discharges are desirable． In this paper， we report the results of two related studies aimed at improving the applicability of electric field measuring techniques． In the first study， the factors that influence the detection limits for electric field measurements are discussed， and the limits for schemes based on hydrogen and helium are presented． In the second study， we propose a new LIF method， in which the limit set by the pressure mentioned above is avoided by using a two-step excitation scheme． This new scheme， which we call two-step laser induced fluorescence （TSLIF）， uses two tunable lasers to excite separate transitions in argon atoms． Fluorescence is detected from a directly excited level and so collisions are not necessary． We present preliminarily experimental results using this TSLIF scheme．
九州大学の論文
1999-12-30