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 neand the relative calibration coefficients of spectral channels sensitivity Ciwere 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. © 2014 Euratom.
All Science Journal Classification (ASJC) codes
Giudicotti, L., Pasqualotto, R., & Fassina, A. (2014). Dual-angle, self-calibrating Thomson scattering measurements in RFX-MOD. Review of Scientific Instruments, 85(11), -. [11D823]. https://doi.org/10.1063/1.4890409