Compact ECEI system with in-vessel reflective optics for WEST

An electron cyclotron emissionimaging (ECEI)diagnosticsystem for WEST (W Environment for Steady stateTokamak) is under development to study theMHD instabilities affected bytungsten impurities. Thesystem will provide 2-D Te fluctuationimages (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 highspatial ( ≤1.7 cm) and temporal (≤2 μs) resolutions. While the key concept and electronic structure are similar to that of prior ECEIsystems on othertokamak devices such as KSTAR, DIII-D, or ASDEX-U, part of theimaging 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-radiusmirrors 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 thesystem is scheduled on the second experimental WEST campaign end of 2017.
Source: Review of Scientific Instruments - Category: Physics Authors: Source Type: research