Giudicotti L, Pasqualotto R, Fassina A
Consorzio RFX, Corso Stati Uniti, 4, 35127 Padova, Italy.
Department of Industrial Engineering, Padova University, Via Gradenigo 6/a, 35131 Padova, Italy.
Rev Sci Instrum. 2014 Nov;85(11):11D823. doi: 10.1063/1.4890409.
In the multipoint Thomson scattering (TS) system of the RFX-MOD experiment the signals from a few spatial positions can be observed simultaneously under two different scattering angles. In addition the detection system uses optical multiplexing by signal delays in fiber optic cables of different length so that the two sets of TS signals can be observed by the same polychromator. Owing to the dependence of the TS spectrum on the scattering angle, it was then possible to implement self-calibrating TS measurements in which the electron temperature Te, the electron density ne and the relative calibration coefficients of spectral channels sensitivity Ci were simultaneously determined by a suitable analysis of the two sets of TS data collected at the two angles. The analysis has shown that, in spite of the small difference in the spectra obtained at the two angles, reliable values of the relative calibration coefficients can be determined by the analysis of good S/N dual‑angle spectra recorded in a few tens of plasma shots. This analysis suggests that in RFX-MOD the calibration of the entire set of TS polychromators by means of the similar, dual-laser (Nd:YAG/Nd:YLF) TS technique, should be feasible.
在RFX-MOD实验的多点汤姆逊散射（TS）系统中，可以在两个不同的散射角度下同时观测来自几个空间位置的信号。此外，检测系统通过不同长度的光纤电缆中的信号延迟来使用光学复用，以便同一多色仪可以观测两组TS信号。由于TS光谱对散射角的依赖性，因此可以实施自校准TS测量，其中通过对在两个角度收集的两组TS数据进行适当分析，同时确定电子温度Te、电子密度ne以及光谱通道灵敏度Ci的相对校准系数。分析表明，尽管在两个角度获得的光谱差异很小，但通过对几十次等离子体放电中记录的良好信噪比双角度光谱进行分析，可以确定相对校准系数的可靠值。该分析表明，在RFX-MOD中，借助类似的双激光（Nd:YAG/Nd:YLF）TS技术对整个TS多色仪组进行校准应该是可行的。
