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  • Core density fluctuations observed on Tore Supra by Doppler back-scattering: perpendicular velocity modification in high power ICRH experiments

Abstract

Backscattering of a microwave beam close to the cut-off allows for measurement of density fluctuations n(k) at a specified wave-number, selected by the scattering geometry k = -2k(i), where k(i) is the beam wave-number at the reflection layer. On the system installed on Tore Supra, both the scattering wave-number k? and the scattering localisation r/a can be changed during the shot for probing .5 < r/a < .95 and 2 < k < 15 cm{-1}, owing to the steppable probing frequency and the motorised antenna. The perpendicular fluctuation velocity in the laboratory frame is obtained from the Doppler shift of the frequency spectrum Delta = kv. It is dominated by the plasma E(r) x B velocity. In the core, the latter is mainly due to the projection of the toroidal velocity, as this is shown by comparison with measurements by charge exchange recombination spectroscopy. In the set of analysed Tore Supra ohmic and ICRH plasmas, the observed rotation is consistent with a poloidal velocity in the electron diamagnetic direction and/or a toroidal velocity in the counter current direction. Strong modification of velocity profiles and turbulence level are observed together with improved confinement in experiments with ICRH heating at high power and high concentration of minority ions. Preliminary results on associated wave number spectra will also be shown.

Additional information

Authors: HENNEQUIN P, Laboratoire de Physique et Technologie des Plasmas, CNRS, Ecole Polytechnique, Palaiseau (FR);HONORÉ C, Laboratoire de Physique et Technologie des Plasmas, CNRS, Ecole Polytechnique, Palaiseau (FR);TRUC A, Laboratoire de Physique et Technologie des Plasmas, CNRS, Ecole Polytechnique, Palaiseau (FR);QUÉMÉNEUR A, Laboratoire de Physique et Technologie des Plasmas, CNRS, Ecole Polytechnique, Palaiseau (FR);FENZI-BONIZEC C, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);BOURDELLE C, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);GARBET X, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR);HOANG G T, Département de Recherches sur la Fusion Contrôlée, Association Euratom-CEA sur la Fusion, CEA Cadarache, Saint-Paul-lez-Durance (FR)
Bibliographic Reference: An oral paper given at: 7th International Reflectometry Workshop for Fusion Plasma Diagnostics Organised by: Max-Planck-Institut für Plasmaphysik, Garching (DE) Held at: Max-Planck-Institut für Plasmaphysik, Garching (DE)
Availability: Available from Association EURATOM-CEA, Département de Recherches sur la Fusion Contrôlée, CEA Cadarache, F-13108 St Paul-Lez-Durance, France Tel: (+33) 4 42 25 70 01; Fax: (+33) 4 42 25 64 21 E-mail: dirdrfc@drfc.cad.cea.fr
Record Number: 200518337 / Last updated on: 2005-09-26
Category: PUBLICATION
Original language: en
Available languages: en