title: Improved spatial calibration for the CXRS system on EAST.
abstract: A Charge eXchange Recombination Spectroscopy (CXRS) diagnostic system has been developed to measure profiles of ion temperature and rotation since 2014 on EAST. Several techniques have been developed to improve the spatial calibration of the CXRS diagnostic. The sightline location was obtained by measuring the coordinates of three points on each sightline using an articulated flexible coordinate measuring arm when the vessel was accessible. After vacuum pumping, the effect of pressure change in the vacuum vessel was evaluated by observing the movement of the light spot from back-illuminated sightlines on the first wall using the newly developed articulated inspection arm. In addition, the rotation of the periscope after vacuum pumping was derived by using the Doppler shift of neutral beam emission spectra without magnetic field. Combining these techniques, improved spatial calibration was implemented to provide a complete and accurate description of the EAST CXRS system. Due to the effects of the change of air pressure, a ∼0.4° periscope rotation, yielding a ∼20 mm movement of the major radius of observation positions to the lower field side, was derived. Results of Zeeman splitting of neutral beam emission spectra with magnetic field also showed good agreement with the calibration results.
authors.affiliation: School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China.
authors.forename: X H
authors.initials: XH
authors.lastname: Yin
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Y Y
authors.initials: YY
authors.lastname: Li
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: J
authors.initials: J
authors.lastname: Fu
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: D
authors.initials: D
authors.lastname: Jiang
authors.affiliation: School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China.
authors.forename: S Y
authors.initials: SY
authors.lastname: Feng
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Gu
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: B
authors.initials: B
authors.lastname: Lyu
authors.affiliation: School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Shi
authors.affiliation: School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, China.
authors.forename: M Y
authors.initials: MY
authors.lastname: Ye
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China.
authors.forename: B N
authors.initials: BN
authors.lastname: Wan