title: Compact ECEI system with in-vessel reflective optics for WEST.
abstract: An electron cyclotron emission imaging (ECEI) diagnostic system for WEST (W Environment for Steady state Tokamak) is under development to study the MHD instabilities affected by tungsten impurities. The system will provide 2-D Tefluctuation images (width × height = ∼18 cm × ∼ 34 cm at low field side and ∼13 cm × ∼ 39 cm at high field side) from a poloidal cross section with high spatial (≤1.7 cm) and temporal (≤2 μs) resolutions. While the key concept and electronic structure are similar to that of prior ECEI systems on other tokamak devices such as KSTAR, DIII-D, or ASDEX-U, part of the imaging optics have to be placed inside the vacuum vessel in order to resolve issues on limited installation space and longer beam path to the detector position. The in-vessel optics consisting of two large curvature-radius mirrors are expected to withstand the extreme heating on long-pulse operation scenario (∼1000 s). The out-vessel optical housing is constructed as compact as possible to remove easily from the installation site in case of necessity. Commissioning of the system is scheduled on the second experimental WEST campaign end of 2017.
authors.affiliation: Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea.
authors.forename: Y B
authors.initials: YB
authors.lastname: Nam
authors.affiliation: Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea.
authors.forename: H K
authors.initials: HK
authors.lastname: Park
authors.affiliation: Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea.
authors.forename: W
authors.initials: W
authors.lastname: Lee
authors.affiliation: Department of Physics, Pohang University of Science and Technology, Pohang 37673, South Korea.
authors.forename: G S
authors.initials: GS
authors.lastname: Yun
authors.affiliation: Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea.
authors.forename: M
authors.initials: M
authors.lastname: Kim
authors.affiliation: CEA, IRFM, F-13108 Saint Paul lez Durance, France.
authors.forename: R
authors.initials: R
authors.lastname: Sabot
authors.affiliation: CEA, IRFM, F-13108 Saint Paul lez Durance, France.
authors.forename: D
authors.initials: D
authors.lastname: Elbeze
authors.affiliation: CEA, IRFM, F-13108 Saint Paul lez Durance, France.
authors.forename: P
authors.initials: P
authors.lastname: Lotte
authors.affiliation: CEA, IRFM, F-13108 Saint Paul lez Durance, France.
authors.forename: J
authors.initials: J
authors.lastname: Shen