Fluctuation BES measurements with the ITER core CXRS prototype spectrometer

• Published in: Fusion engineering and design Vol. 88; no. 6-8; pp. 1386 - 1389
• Main Authors: Pokol, G.I., Zoletnik, S., Dunai, D., Marchuk, O., Baross, T., Erdei, G., Grunda, G., Kiss, I.G., Kovacsik, A., v.Hellermann, M., Lischtschenko, O., Biel, W., Jaspers, R.J.E., Durkut, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2013
• Subjects: Beam emission; Bundling; Channels; CXRS; Detectors; Diagnostic systems; Fluctuation; ITER; MHD; Prototypes; Simulation; Spectrometers; TEXTOR; Validation; Validation; Beam emission; Fluctuation; MHD; CXRS; ITER; TEXTOR
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2013.02.171

•We integrated a fluctuation beam emission measurement into the ITER CXRS prototype spectrometer.•The fluctuation BES measurement provided data at TEXTOR that agree well with the simulation based on the Simulation Of Spectra package.•The same simulation method has been used to evaluate the feasibility of a fluctuation BES measurement on the ITER DNB using the CXRS periscopes.
The ITER core CXRS diagnostic system collects the light emitted from the interaction of the diagnostic neutral beam with the core plasma and guides it via a mirror labyrinth through the upper port plug #3 towards a fiber bundle, which then transmits the light into a set of spectrometers for spectral analysis. In order to test the accessibility of the special parameter range required for the ITER measurement, a prototype spectrometer was built and operated successfully at the TEXTOR tokamak. In addition to the He/Be, C/Ne and H/D/T regular spectral channels, a fluctuation beam emission spectroscopy (BES) system has been integrated to measure core MHD activity, and validate corresponding ITER simulation results. The fluctuation system can be operated as an alternative to the spectral BES measurement, and has 8 spatial channels sampled at 2MHz. In this paper, we present details of the fluctuation BES system and its interface to the ITER prototype spectrometer along with simulation and measurement results at TEXTOR. We show that the measurement fully confirms the simulation results on achievable photon current at the detector and on the signal to noise ratio.