プラズマ計測におけるレーザートムソン散乱スペクトルの微弱光観測の極限的性能

概要

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The ultimate detection limit of laser Thomson scattering for plasma diagnostics is discussed, in terms of the signal-to-noise ratio (SNR) for the detected photon numbers against various possible noise sources. First, the general expression of SNR is given, and detailed discussions are made for Thomson scattering intensities against noises caused by Rayleigh scattering and the stray light, based on measured slit functions. Possible means of improving the obtained detection limit are discussed, and it was found that the refinement of spectrometers would be the clue for achieving the detection limit in electron density of the order of 10^15 m^-3, typical of an RF (ratio-frequency) capacitively-coupled plasma. A further discussion is made for a possibility of performing a Thomson scattering experiment on discharges realized in a plasma display panel. Following the above findings, it looks feasible to carry out the experiment even for this plasma having a relatively modest electron density of 10^18m^-3 but extremely small scattering volume (0.1*0.1*0.3mm^3).
九州大学の論文
1999-09-30