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  • IF =1.193

  • ISSN 1009-0630

  • e-ISSN 2058-6272

  • CN 34-1187/TL

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Content of The 3rd Chinese laser and microwave aided plasma diagnostics workshop in our journal
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Quasi-3D electron cyclotron emission imaging on J-TEXT
Zhenling ZHAO (赵朕领)1, Yilun ZHU (朱逸伦)1, Li TONG (仝丽)1, et al.
Plasma Sci. Technol.    2017, 19(9): 094001; doi: 10.1088/2058-6272/aa750d
Abstract190)      PDF (830KB)(431)      

Electron cyclotron emission imaging (ECEI) can provide measurements of 2D electron temperature fuctuation with high temporal and spatial resolution in magnetic fusion plasma devices. Two ECEI systems located in different toroidal ports with 67.5 degree separation have been implemented on J-TEXT to study the 3D structure of magnetohydrodynamic (MHD) instabilities. Each system consists of 12 (vertical) × 16 (horizontal) = 192 channels and the image of the 2nd harmonic X-mode electron cyclotron emission can be captured continuously in the core plasma region. The feld curvature adjustment lens concept is developed to control the imaging plane for receiving optics of the ECEI systems. Field curvature of the image can be controlled to match the emission layer. Consequently, a quasi-3D image of the MHD instability in the core of the plasma has been achieved.

Optimization of the optical system for electron cyclotron emission imaging diagnostics on the HL-2A tokamak
Min JIANG (蒋敏)1,3, Zhongbing SHI (石中兵)1 and Yilun ZHU (朱逸伦)2
Plasma Sci. Technol.    2017, 19(8): 084001; doi: 10.1088/2058-6272/aa62f7
Abstract189)      PDF (1493KB)(483)      

The optical system of the electron cyclotron emission imaging diagnostics on the HL-2A tokamak has been optimized in both the narrow zoom pattern and the wide zoom pattern. The two main features of the improved optical system are (1) larger coverage of the measurement region in the plasma and (2) a flatter imaging surface. The new optics has good focal characteristics over the whole plasma cross section. The curvature of the field of the image surface (ΔR between the core channel and the edge channel) is within 5.3 cm in the narrow zoom pattern and 6.7 cm in the wide zoom pattern after optimization, whereas the values with the present optics were 23 cm in the narrow zoom pattern and 15 cm in the wide zoom pattern. The optics will be fabricated, tested and
installed on the HL-2A tokamak before the next experimental campaign.

An accurate automated technique for quasi-optics measurement of the microwave diagnostics for fusion plasma
Jianqiang HU (胡健强), Ahdi LIU (刘阿娣), Chu ZHOU (周楚), Xiaohui ZHANG (张小辉), Mingyuan WANG (王明远), Jin ZHANG (张津), Xi FENG (冯喜), Hong LI (李弘), Jinlin XIE (谢锦林), Wandong LIU (刘万东) and Changxuan YU (俞昌旋)
Plasma Sci. Technol.    2017, 19(8): 084002; doi: 10.1088/2058-6272/aa6794
Abstract206)      PDF (3766KB)(624)      

A new integrated technique for fast and accurate measurement of the quasi-optics, especially for the microwave/millimeter wave diagnostic systems of fusion plasma, has been developed. Using the LabVIEW-based comprehensive scanning system, we can realize not only automatic but also fast and accurate measurement, which will help to eliminate the effects of temperature drift and standing wave/multi-reflection. With the Matlab-based asymmetric two-dimensional Gaussian fitting method, all the desired parameters of the microwave beam can be obtained. This technique can be used in the design and testing of microwave diagnostic systems such as reflectometers and the electron cyclotron emission imaging diagnostic systems of the Experimental Advanced Superconducting Tokamak.

Development of an HCN dual laser for the interferometer on EAST
Gen LI (李根)1, Xuechao WEI (魏学朝)2, Haiqing LIU (刘海庆)2, Junjie SHEN (申俊杰)1, Yinxian JIE (揭银先)2, Hui LIAN (连辉)2,
Plasma Sci. Technol.    2017, 19(8): 084003; doi: 10.1088/2058-6272/aa667b
Abstract176)      PDF (1993KB)(521)      

A two-color continuous wave (CW) discharge-pumped far-infrared (FIR) hydrogen cyanide (HCN) laser was developed as the source of an interferometer for measuring the line-averaged electron density in the Experimental Advanced Superconducting Tokamak (EAST). The output power of the dual laser system was about 120mW from each laser on the 337 μm (0.89 THz) line. The polarization of each output beam was fixed using thin tungsten filaments and oscillated
in the EH11 mode. Different megahertz intermediate frequencies (IF) and a slight frequency offset (∼1 MHz) were generated in this system to replace the traditional rotating grating with ∼10 kHz IF, and this can improve the time resolution of the interferometer significantly. The experimental result showed that different IF signals were obtained by successfully adjusting the cavity length. In particular, the beat frequency was captured at ∼1.3 MHz by a Schottky mixer when the length of the resonant cavities was changed by 5 μm by an automatic adjustment system. In order to study the character of IF, a long time record of the IF signal was carried out, and the IF signal could be stabilized for a few minutes in the range of 2 MHz to 3 MHz. A realtime IF stability control system was initially designed for long pulse discharge experiments on the EAST. The ∼MHz frequency response and good phase sensitivity of the dual laser HCN interferometer will allow the system to track fast density profiles and resolve fast MHD events, such as tearing/neoclassical tearing, disruptions, etc.

A digital wide range neutron flux measuring system for HL-2A
Chen YUAN (袁晨)1,2, Jun WU (吴军)1,2 and Zejie YIN (阴泽杰)1,2
Plasma Sci. Technol.    2017, 19(8): 084004; doi: 10.1088/2058-6272/aa6bf1
Abstract183)      PDF (1618KB)(396)      

To achieve wide-range, high-integration, and real-time performance on the neutron flux measurement on the HL-2A tokamak, a digital neutron flux measuring (DNFM) system based on the peripheral component interconnection (PCI) eXtension for Instrumentation express (PXIe) bus was designed. This system comprises a charge-sensitive preamplifier and a field programmable gate array (FPGA)-based main electronics plug-in. The DNFM totally covers source-range and intermediate-range neutron flux measurements, and increases system integration by a large margin through joining the pulse-counting mode and Campbell mode. Meanwhile, the neutron flux estimation method based on pulse piling proportions is able to choose and switch measuring modes in accordance with current
flux, and this ensures the accuracy of measurements when the neutron flux changes suddenly. It has been demonstrated by simulated signals that the DNFM enhances the full-scale measuring range up to 1.9×108 cm−2 s−1, with relative error below 6.1%. The DNFM has been verified to provide a high temporal sensitivity at 10ms time intervals on a single fission chamber on HL-2A.

An intelligent remote control system for ECEI on EAST
Dongxu CHEN (陈东旭), Yilun ZHU (朱逸伦), Zhenling ZHAO (赵朕领), Chengming QU (渠承明), Wang LIAO (廖望), Jinlin XIE (谢锦林) and Wandong LIU (刘万东)
Plasma Sci. Technol.    2017, 19(8): 084005; doi: 10.1088/2058-6272/aa6e4a
Abstract165)      PDF (1542KB)(458)      

An intelligent remote control system based on a power distribution unit (PDU) and Arduino has been designed for the electron cyclotron emission imaging (ECEI) system on Experimental Advanced Superconducting Tokamak (EAST). This intelligent system has three major functions: ECEI system reboot, measurement region adjustment and signal amplitude optimization. The observation region of ECEI can be modified for different physics proposals by remotely tuning
the optical and electronics systems. Via the remote adjustment of the attenuation level, the ECEI intermediate frequency signal amplitude can be efficiently optimized. The remote control system provides a feasible and reliable solution for the improvement of signal quality and the efficiency of the ECEI diagnostic system, which is also valuable for other diagnostic systems.