Li Xiaoliang, Chen Ran, Xu Guosheng, Domier Calvin, Liu Xianzi, Zhang Yiwei, Zhou Tianfu, Zhu Yilun, Yu Guanying, Qiu Shasha, Yu Hai, Luhmann Neville C
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China.
University of California Davis, Davis, California 95616, USA.
Rev Sci Instrum. 2024 Jul 1;95(7). doi: 10.1063/5.0215730.
Microwave reflectometry is an invaluable diagnostic tool for measuring electron density profiles in large fusion devices. Density fluctuations near the plasma cutoff layer, particularly those that are time-varying on the timescale of the reflectometry measurement, can result in distortions in phase and/or amplitude of the reflected waveform, which present challenges to the accuracy of the reconstructed profile. The ultra-short pulse reflectometry (USPR) technique eliminates the time-varying issue in that reflectometry data are collected on a nanosecond timescale, essentially freezing the fluctuations in place. An X-mode dedicated 32-channel USPR system has been developed and installed on the EAST, covering the operation frequency range from 52 to 92 GHz. This system enables high-resolution density profile measurements in the plasma pedestal and scrape-off layer, with resolutions reaching 5 mm and 1 μs, respectively. Laboratory testing of the system performance has been conducted, demonstrating the potential of the USPR technique to provide accurate and high-temporal-resolution density profiles in challenging plasma environments.
微波反射测量法是用于测量大型聚变装置中电子密度分布的一种极为重要的诊断工具。等离子体截止层附近的密度涨落，尤其是那些在反射测量时间尺度上随时间变化的涨落，会导致反射波形的相位和/或幅度发生畸变，这给重建分布的准确性带来了挑战。超短脉冲反射测量法（USPR）技术消除了随时间变化的问题，因为反射测量数据是在纳秒时间尺度上收集的，基本上将涨落冻结在了原地。已开发出一种X模专用32通道USPR系统并安装在了EAST上，覆盖52至92吉赫兹的工作频率范围。该系统能够在等离子体基座和刮离层中进行高分辨率密度分布测量，分辨率分别达到5毫米和1微秒。已对该系统性能进行了实验室测试，证明了USPR技术在具有挑战性的等离子体环境中提供准确且高时间分辨率密度分布的潜力。
