Electron temperature profiles are routinely measured on FTU tokamak from second harmonic Electron Cyclotron Emission in the extraordinary polarization. Spatial resolution of the diagnostic is 2 cm; time resolution achieved for the whole ECE spectrum by a fast scanning Fourier Transform Spectrometer is 5 ms, while about 1 μs is obtained at twelve radial locations simultaneously by means of a twelve channel grating polichromator.
P. Buratti, P. Buratti,
"ECE diagnostics on the Frascati Tokamak upgrade", Proc. SPIE 1576, 16th International Conference on Infrared and Millimeter Waves, 15765J (1 October 1991); doi: 10.1117/12.2297912; https://doi.org/10.1117/12.2297912