Quasi-optical electron cyclotron emission imaging diagnostic advancements on the J-TEXT tokamak

• Published in: Fusion engineering and design 2020-06, Vol.155, p.111636, Article 111636
• Main Authors: Xie, X.L., Zhou, J., Zhu, Y., Pan, X.M., Zhou, H., Yu, G., Luhmann, N.C., Zhuang, G., Yang, Z.J.
• Format: Article
• Language: English
• Subjects: Antenna arrays; Cyclotrons; Diagnostic systems; Electron cyclotron emission imaging diagnostics; Emission; Imaging; Insertion loss; Local oscillator optics system; Major optics system; Mixers; Optics; Remote control; Subsystems; Tokamak; Tokamak devices
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2020.111636

•The upgraded major imaging optics is designed to work in both 16 and 24 vertical channels configurations.•The radial focus position of each array is able to move from LFS edge to HFS edge independently without affecting the image plane shapes.•Two LO optics systems are demonstrated enough coupling efficiency to drive all mixers on antenna arrays according to the laboratory test. The new quasi-optical electron cyclotron emission imaging (ECEI) diagnostic system on the J-TEXT tokamak has been developed and characterized. The quasi-optical system consists of two subsystems: the major imaging optics system for plasma imaging and the local oscillator (LO) optics system to drive the mixers in the antenna array. For the updated demands, some modifications and adaptations are accomplished on the major imaging optics. The vertical zoom ratio, focus capability, and field curvature have been measured on the J-TEXT facility, with good matching with the simulation results. For the various experimental requirements on J-TEXT, the remote control system is adopted for the major imaging optics. As for LO optics systems, spherical LO optics and hyperbolic LO optics have demonstrated high performance. Uniform power deposition has been optimized to drive all mixers and minimize insertion loss.