A fringe jump counting method for the phase measurement in the HCN laser interferometer on EAST and its FPGA-based implementation  

作　　者：姚远 杨曜 提昂 宋扬 张家敏 王琰 张耀 刘海庆 揭银先 Yuan YAO;Yao YANG;Ang TI;Yang SONG;Jiamin ZHANG;Yan WANG;Yao ZHANG;Haiqing LIU;Yinxian JIE(Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,People’s Republic of China;Anhui Electrical Engineering Professional Technique College,Hefei 230022,People’s Republic of China;Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,People’s Republic of China)

机构地区：[1]Institute of Plasma Physics,Chinese Academy of Sciences,Hefei 230031,People’s Republic of China [2]Anhui Electrical Engineering Professional Technique College,Hefei 230022,People’s Republic of China [3]Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,People’s Republic of China

出　　处：《Plasma Science and Technology》2024年第4期156-161,共6页等离子体科学和技术（英文版）

基　　金：funded and supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228);the HFIPS Director’s Fund(No.YZJJKX202301);Anhui Provincial Major Science and Technology Project(No.2023z020004);Task JB22001 from the Anhui Provincial Department of Economic and Information Technology。

摘　　要：Electron density in fusion plasma is usually diagnosed using laser-aided interferometers. The phase difference signal obtained after phase demodulation is wrapped, which is also called a fringe jump. A method has been developed to unwrap the phase difference signal in real time using FPGA, specifically designed to handle fringe jumps in the hydrogen cyanide(HCN) laser interferometer on the EAST superconducting tokamak. This method is designed for a phase demodulator using the fast Fourier transform(FFT) method at the front end. The method is better adapted for hardware implementation compared to complex mathematical analysis algorithms, such as field programmable gate array(FPGA). It has been applied to process the phase measurement results of the HCN laser interferometer on EAST in real time. Electron density results show good confidence in the fringe jump unwrapping method. Further possible application in other laser interferometers, such as the POlarimeter-INTerferometer(POINT)system on EAST tokamak is also discussed.

关 键 词：electron density laser-aided interferometer fringe jump unwrapping FPGA EAST 

分 类 号：TL631.24[核科学技术—核技术及应用] TN791[电子电信—电路与系统]