Development of signal analysis method for the motional Stark effect diagnostic on EAST

摘要

A pilot single-channel Motional Stark Effect (MSE) diagnostic has been developed on EAST since 2015. The dual photo-elastic modulators (PEM) were employed to encode the polarization angle into a time-varying signal. The pitch angle was related to the ratio of modulation amplitude at the second harmonic frequency. A digital harmonic analyzer (DHA) technique was developed for extracting the second harmonic amplitude. The results were validated with a hardware phase lock-in amplifier, and is also consistent with the software dual phase-locking algorithm.