(IT/P1-26) Review of Beam Aided Diagnostics for ITER

M.G. von Hellermann1), R. Jaspers1), W. Biel2), O. Neubauer2), N. Hawkes3), Y. Kaschuck4), V. Serov4), S. Tugarinov4), D. Thomas5), W. Vliegenthart6
 
1) FOM Institute for Plasma Physics Rijnhuizen, Nieuwegein, Netherlands
1 FOM-Institute for Plasma Physics Rijnhuizen*, Association EURATOM, Netherlands, www.rijnh.nl; 2 Institut für Plasmaphysik*, Forschungszentrum Jülich, Association EURATOM-FZJ, Germany, www.fz-juelich.de/ipp; 3UKAEA Culham Laboratory Euratom Association, Abingdon UK; 4TRINITI Troitsk, RF; 5General Atomics, San Diego, USA, 6TNO Science & Industries, Delft, NL, * Partners in the Trilateral Euregio Cluster

Abstract.  A reassessment of the proposed package of beam aided diagnostic systems for ITER has led to a number of new developments. As a result of a joint development effort and comprehensive optimisation studies (c.f. [M. Von Hellermann, ``Active Charge Exchange Spectroscopy (CXRS) and Beam Emission Spectroscopy (BES+MSE) with Diagnostic Neutral Beam (DNB)” (EFDA contract: 01.649, 2003; not publicly available, contact: mgvh@rijnh.nl)]) two separate CXRS (Charge Exchange Recombination Spectroscopy) and BES (Beam Emission Spectroscopy ) systems both based on a dedicated Diagnostic Neutral Beam (H0, 100 keV/amu, 22 A) injected radially into the plasma have been proposed: A `Core CXRS’ system (EU) which covers dominantly the inner half of the confined plasma, and an ‘Edge CXRS’ system (RF) which ensures a high radial resolution in the outer half of the plasma. The Core system utilises an upper port periscope, and two periscopes located in an equatorial port are envisaged for the Edge CX system. The equatorial port is shared with a dedicated MSE (Motional Stark Effect) system for the measurement of magnetic field pitch angles making use of the Heating Neutral Beams. A complementary MSE approach is proposed for the exploitation of intensity line ratios as measured by the BES data from upper and equatorial ports. The optical layouts of the two systems have been recently reviewed and alignment and instrumentation schemes were developed. A comprehensive multi-parameter spectral modelling effort based on an ITER reference scenario ( ne(0) = 1020m-3, Te(0) = Ti(0) = 20 keV, B = 5.2 T, Zeff = 1.6) the actual observation geometry, and modelling of atomic processes, has enabled an update of expected performances in terms of measurement accuracies, time and spatial resolution. The key message is that the measurement of radially resolved profiles of ion temperature, plasma rotation and ion densities, including that of the helium ash, appear to be feasible and, moreover, Signal-To-Noise numbers well above 10 are expected for the main part of the confined plasma, that is for 0.2 < r/a < 1 for the Upper port and 0.4 < r/a < 1 for the E-port. Pitch angle measurement based on line ratios in the MSE multiplet spectrum are predicted with error margins below 10% and total magnetic field values deduced from line separations with error of less than 1% for the region 0.2 < r/a < 1.

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