Electron cyclotron emission imaging (ECEI) is widely utilized for measuring temperature perturbations in tokamaks. ECEI measurements are typically processed by normalizing fluctuations relative to the mean time-period signal. However, measuring phenomena with low temperature disturbance proves challenging and requires calibration to obtain static or low-disturbance magnetohydrodynamic (MHD) phenomena. This paper employs the hypothesis of temperature flattening during sawtooth collapse, along with two-dimensional rotation matching with GS displacement and a linear extrapolation method, to perform relative calibration of the ECEI channel. This paper reconstructed a two-dimensional image of the relative calibrated electron temperature and subsequently analyze the experimental phenomenon.

Electron cyclotron emission imaging (ECEI);,Sawtooth;,Relative calibration.