title: Far-forward collective scattering measurements by FIR polarimeter-interferometer on J-TEXT tokamak.
abstract: The multi-channel three-wave polarimeter-interferometer system on J-TEXT tokamak has been exploited to measure far-forward collective scattering from electron density fluctuations. The diagnostic utilizes far infrared lasers operated at 432 μm with 17-channel vertical chords (3 cm chord spacing), covering the entire cross section of plasma. Scattering laser power is measured using a high-sensitivity Schottky planar diode mixer which can also detect polarimetric and interferometric phase simultaneously. The system provides a line-integrated measurement of density fluctuations with maximum measurable wave number: k⊥max≤ 2 cm-1and time response up to 350 kHz. Feasibility of the diagnostic has been tested, showing higher sensitivity to detect fluctuation than interferometric measurement. Capability of providing spatial-resolved information of fluctuation has also been demonstrated in preliminary experimental applications.
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: P
authors.initials: P
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: L
authors.initials: L
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: Y N
authors.initials: YN
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
authors.forename: G
authors.initials: G
authors.lastname: Zhuang