The Experimental Research On TV Thomson Scattering Diagnostic System For EAST

The electron temperature and density of the plasma are two of the very important basic parameters in fusion research,and their precise measurements with high temporal and spatial resolution plays an irreplaceable role in the steady state operation of the Tokamak with high parameters and the frontier physical problems research of the pedestal region.To improve the temporal and spatial resolution,and accuracy of the electron temperature and density measurement at the EAST edge region,the feasibility of TV Thomson scattering（TVTS）diagnosis system is firstly carried out based on the principle of the diagnosis.And then based on the research of the high energy and frequency laser source system,high efficient optical collection system,spectral detection system with high spectral resolution,a TVTS diagnostic system with high temporal,spatial and spectral resolution has been developed in this paper,and the performance of this system is tested.The main details are as follows:（1）The feasibility analysis of the developed EAST TVTS diagnostic system is carried out based on the TVTS diagnosis,and the feasibility of the system is verified theoretically.The parameters of the optical system are determined to maximize the collected scattering signal.And then based on the determined parameters and achievable experimental conditions,the effective and noise counts of the detector are analyzed and calculated,and the feasibility of the TVTS system is verified.（2）A high energy and frequency laser system is developed for EAST TVTS diagnostic system to ensure that enough scattered photons are generated in the measurement region.By designing the laser from four parts:fundamental frequency module,frequency multiplication module,water-cooling module and power module,a high energy and frequency light source with stable output of 1064 nm and 532 nm is developed.By planning,monitoring and controling of the laser path,the laser can accurately cross the edge plasma according the set path.（3）An efficient optical collection system is developed for EAST TVTS diagnostic system to ensure that enough scattered photons are collected.Based on the principle of maximizing the collected scattered photons and minimizing the transmission loss,the optical collection lenses with aspherical mirror and coaxial antitelesephoto structure is designed which can effectively realize the collection of scattered photons in a large entrance pupil and field of view.Meanwhile,the stable mounting rack and 2d adjustable fiber holder are designed to achieve the accurate alignment of optical fiber and collected photons.（4）A spectral dection system with high spectral resolution is developed for EAST TVTS diagnostic system to realize the spectroscopic detection of weak scattering signals.Based on the analysis of detector system,grating,performance requirements,theoretical parameters and lens group structure,a Littrow structure spectrometer system equipped with reflective plane grating is designed,so that the spectrometer system has a spectral resolution of not less than 5 nm when the entrance slit is 1.5 mm,which enables the system to analyze the scattering spectra at electron temperature as low as 20 eV.Based on the structural improvement of optical and mechanical inside the spectrometer,and the construction of an optical switch system outside the spectrometer,the rejection ratio of stray light at 532 nm is as low as 10^-6,and the scattering signal with high signal-to-noise ratio is obtained.（5）The test of the developed EAST TVTS diagnostic system is carried out,and the feasibility of the system is verified practically.A timing control system combining hardware and software is developed.By setting the timing control system and the data acquisition system,the system can get high signal-to-noise ratio scattering signals with complete discharge information.Based on the above designed system parameters,calibration coefficients of the spectral dection system and SELDEN model,the measurement data of the designed TVTS system are analyzed,and the feasibility of the system is verified.