Vibration analysis of the Thomson Scattering diagnostics optical transmission system on EAST tokamak

Abstract

A series of vibration source from the EAST tokamak complicated experimental environment would result in the laser path misalignment and the collected scattered laser signal attenuation, which leads to a measurement error of the Thomson Scattering (TS) diagnostics system. Two methods have been designed for the vibration analysis of the TS diagnostics optical transmission system, a passive one and an active one. The optical transmission system contains of a double deck optical table with 4 reflectors and a photon collection system. The vibration analysis includes 4 points of reflectors along the laser path, 1 point of the photon collection system, and the ground of EAST experimental hall. The passive method used a vibration spectrum analyzer and 7 vertical speed sensors measuring the standard deviation of the vibration noise, which refers to the virtual value of vibration, and a data analysis system. The active method used a hammer to simulate the vibration source of the experimental hall ground, and 15 accelerometers to measure the three-dimensional vibration spectrum of 5 points along the optical transmission system. The vibration isolation efficiency (IE) of the optical transmission system has been presented, and the vibration asynchrony of the 5 points also has been observed. The results of two methods are comparatively studied, and the active one is considered to be more credible.