Kiel 2011 – scientific programme

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P: Fachverband Plasmaphysik

P 21: Diagnostik / Plasma-Wand-Wechselwirkung

P 21.7: Talk

Thursday, March 31, 2011, 12:40–12:55, HS C

Determination of edge radial electric fields via charge exchange recombination spectroscopy (CXRS) at ASDEX Upgrade — •E. Viezzer, T. Pütterich, R. Dux, R. M. McDermott, and the ASDEX Upgrade Team — Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany

A new edge CXRS diagnostic, which utilizes one of the neutral heating beams, has been installed in the ASDEX Upgrade tokamak. The system provides highly resolved radial profiles (∼5mm) of impurity ion temperature, density and poloidal rotation, which are determined directly from the observed spectra, i.e. from the Doppler width, the Doppler shift and the line intensity. From these profiles, in conjunction with the data from a second edge CXRS diagnostic, which provides toroidal plasma rotation, the edge radial electric field (E_r) can be determined. E_r can be calculated using the radial force balance which relates E_r with ∇p/n as well as with both poloidal and toroidal rotation. It is widely accepted that E×B velocity shear is fundamental for suppressing edge turbulence thus, aiding the formation of the edge transport barriers and enabling the L-H transition. However, the origin and development of E_r is still an open issue. The E_r profile is determined in type-I ELMy H-mode discharges using CX measurements of several different fully ionized impurity ions. This provides a consistency check and validates the new CX system as all analyses must arrive at the same E_r profile regardless of the impurity species used. In addition, the effect of the recently installed resonant magnetic perturbation coils on the E_r profile is investigated.