Electron Cyclotron Emission diagnostics

Electron Cyclotron Emission (ECE) diagnostic makes use of the electromagnetic radiation exiting the plasma to measure its electron temperature. It is one of the most successful diagnostics for plasma temperature and a good example of passive measurement, i.e. not using any external probe. The radial dependance of the magnetic field in a tokamak is B(R)=B₀R₀/R where R is the major radius and subscript 0 denotes the values at tokamak center. B is then higher towards tokamak center (small R) or High Field Side (HFS) and lower at larger R or Low Field Side (LFS). Combining this dependance with eq. (2), the measurement of ECE spectrum intensity I(ω) provides spatially resolved temperature measurements (T_e profile).

Rotating mirrors Michelson interferometer for the FTU ECE diagnostic — Rotating mirrors Michelson interferometer for ECE diagnostic on FTU (1989-2019)

Four-channel rotating mirrors Michelson interferometer for the JET KK5 ECE diagnostic — 4-channels rotating mirrors Michelson interferometer for JET ECE diagnostic (KK5). (2005-2023)