| Spectroscopy diagnostic is the main method to study the behavior of ions in fusion plasma.In recent years,with the increasing concern about of Tokamak plasma turbulence and MHD research,the rapid changes of ion behavior(ion temperature,rotation speed and impurity radiation,etc.)in the corresponding process have attracted more and more attention.Therefore,the demand for high-speed spectroscopy diagnostic is becoming more and more urgent.Based on the UF-CXRS diagnostic system of the EAST,in this paper,the design method of each part in the photodetection system is analyzed systematically,and a photoelectric detection system with a time resolution of microseconds is designed.A high-resolution photodetection system is designed in this paper for the UF-CXRS diagnostic system on the EAST.Based on the estimation of the photon flux entering the detector,the photomultiplier tube was selected as the detector after comparing the working characteristics of various detectors.The mathematical model is used to describe the relationship between the photomultiplier output signal,noise and photon flux.The working characteristics of the transimpedance circuit and the output noise are analyzed in detail.The transimpedance circuit is combined with the voltage amplifying circuit,the active filter circuit and the frequency compensation circuit to form three signal processing circuit schemes.After simulation analysis and experimental testing,the circuit scheme combining the transimpedance circuit and the active filter circuit weakens the high frequency noise and ensures that the output signal has a good signal to noise ratio.After testing,the detection system has a time resolution of 2.5μs and a photon flux lower limit of 10~7ph/s,which satisfies the spectroscopic system requirements.The photodetection system is applied to the spectral diagnostic system of the J-TEXT,which improves the time resolution of the system,and effectively observes the MHD activity in the plasma by monitoring the CV radiation. |
PDF Full Text Request