MEPhIST-0 Tokamak Microwave Interferometer with Frequency Sweeping

The design of the MEPhIST-0 tokamak microwave interferometer and its system of data acquisition and processing are described. Examples of the time evolution of the linear electron density in MEPhIST-0 discharges are presented. The use of a phasemeter based on AD8302 detectors and digital post-processing of interferometer signals is compared. The beam refraction in the MEPhIST-0 chamber has been calculated. The possibility of plasma probing with a microwave interferometer for single- and two-pass configurations has been evaluated. It is shown that the transition to single-pass plasma probing allows the upper limit of the measured density to be significantly expanded (up to n0 = 3 × 1019 m−3).