Study on Differences of ECE and High-Resolution Thomson Scattering temperature measurements in DT (Deuterium-Tritium) plasmas on JET

In Deuterium Plasmas differences were detected in JET between electron temperature measurements (Te) made by Electron Cyclotron Emission - Te_ECE - and Thomson Scattering diagnostics systems (Te_TS) [1]. Similar behaviour was found in TFTR [2]. Plasmas heated by ECRH (Electron Cyclotron Heating) in Deuterium on FTU showed T_ECE < T_TS for 8 KeV ≤ Te ≤ 14 keV [3]. These differences can be due to the non-Maxwellian nature of the Electron velocity Distribution Function (EDF) [5,6]. The radiation temperature (Trad) measured by ECE is equal to the Te only for a Maxwellian plasma: being Trad dependent on the derivative of the EDF with respect to perpendicular velocity [5]. This paper describes differences of Te measured by ECE (ECE_MP, Martin-Puplett interferometer) and High-Resolution Thomson Scattering (HRTS) diagnostic. HRTS gives independent information on these differences, having shorter space resolution (2 cm), and faster repetition rate (20 Hz) on a different line of sight (16 cm from the magnetic centre): HRTS measurements confirm the trends observed using LIDAR TS [4,5]. Comparison between HRTS and ECE radiometer measurements is also reported (see sec.3).