A novel multi-channel quadrature Doppler backward scattering reflectometer on the HL-2A tokamak

A novel 16-channel fixed frequencyDoppler backward scattering (DBS)reflectometer system has been developed on the HL-2A tokamak. This system is based on the filter-based feedback loopmicrowave source (FFLMS) technique, which has lower phase noise and lower power variation compared with present tunable frequency generation and comb frequency array generation techniques [J. C. Hillesheimet al. Rev. Sci. Instrum.80, 083507 (2009) and W. A. Peebleset al. Rev. Sci. Instrum.81, 10D902 (2010)]. The 16-channel DBS system is comprised of four × four-frequencymicrowave transmitters and direct quadrature demodulation receivers. The working frequencies are 17-24 GHz and 31-38 GHz with the frequency interval of 1 GHz. They are designed tomeasure the localized intermediate wave-number (k⊥ρ∼ 1–2,k⊥∼ 2–9 cm−1) densityfluctuations and the poloidal rotation velocity profile ofturbulence. The details of the system design and laboratory tests are presented. Preliminary results ofDoppler spectrameasured by the multi-channel DBSreflectometer systems are obtained. The plasma rotation andturbulence distribution during supersonic molecular beam injection are analyzed.

Source: Review of Scientific Instruments - November 7, 2016 Category: Physics Authors: Zhongbing Shi, Wulu Zhong, Min Jiang, Zengchen Yang, Boyu Zhang, Peiwan Shi, Wei Chen, Jie Wen, Chengyuan Chen, Bingzhong Fu, Zetian Liu, Xuantong Ding, Qingwei Yang and Xuru Duan Source Type: research