HL-2M 装置扫频 ECE 测量系统研制

为了测量 HL-2M 装置中的电子温度剖面分布，研制了一套扫频电子回旋辐射(SECE)系统。该系统 能够测量装置中心纵场大小在 1.4~2.2T 时的等离子体电子温度。采用扫频外差接收的方式，径向空间分辨达到 2.5cm，时间分辨达到 1ms。接收机前端的准光学系统采用两级金属反射镜的配置，系统能够接收的最小极向光 斑的直径为 1.5cm（波数 k_θ<4.2rad·cm^-1）。系统的频带范围覆盖 33~110GHz，采用 VCO 作为本振源，双边带混频 输出中频信号。后端首次采用高性能对数检波器解调中频，能直接对-70dBm 的微弱信号进行检测，输入-输出工 作区间的动态范围达到 45dB 以上。在实验期间，成功测量到了等离子体中电子逃逸以及回旋辐射产生的信号。

Development of a sweeping-frequency ECE diagnostic on HL-2M tokamak

In order to measure the electron temperature profile on HL-2M, a sweeping frequency electron  cyclotron emission (SECE) system is developed. The system can measure electron temperature of plasma with the  center toroidal field of 1.4~2.2T. The radial spatial resolution is 2.5cm and the temporal resolution is 1ms by using  the method of frequency-swept heterodyne radiometer technique. The quasi-optical system at the front of the  receiver is equipped with two-stage metal mirrors. The minimum diameter of a poloidal spot that the system can  receive is 1.5cm (wave number k_θ<4.2rad·cm^-1) The system covers 33~110GHz bandwidth with 3 voltage  controlled oscillators (VCO) used as the source of local oscillators (LO), and the intermediate frequency (IF)  signal is output by mixing in double sidebands. The backend uses high-performance logarithm detector to  demodulate IF signal for the first time, which can detect the weak signal of -70dBm. The dynamic range of the  input power reaches 45 dB. During HL-2M experiments, the signals generated by runaway electrons and electron  cyclotron emission (ECE) in plasma were measured successfully.