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          Institute: MPI für Plasmaphysik     Collection: Articles, Books, Inbooks     Display Documents

ID: 55969.0, MPI für Plasmaphysik / Articles, Books, Inbooks
Measurement of the plasma radial electric field by the motional Stark effect diagnostic on JET plasmas
Authors:Reyes Cortes, S.; Hawkes, N. C.; Lotte, P.; Fenzi, C.; Stratton, B. C.; Hobirk, J.; De Angelis, R.; Orsitto, F.; Varandas, C. A. F.
Date of Publication (YYYY-MM-DD):2003
Title of Journal:Review of Scientific Instruments
Journal Abbrev.:Rev. Sci. Instrum.
Issue / Number:9
Start Page:1596
End Page:1600
Copyright:Copyright © 2003 American Institute of Physics
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The radial electric field gradient or the E×B flow shear has been pointed out as the underlying mechanism for turbulence suppression, responsible for an internal transport barrier formation in advanced tokamak scenarios. A comprehensive study on these subjects requires a direct measurement of the plasma radial electric field Er. The poloidal component of the magnetic field is assessed by the motional Stark effect (MSE) polarimeter, which is currently a standard diagnostic in fusion devices, allowing a local and nonperturbative measurement of the magnetic pitch angle. A precise measure to the state of polarization of the Stark components gives the information on the direction of the magnetic field. Due to the particular orientation of the Lorentz component, that is nearly perpendicular to Er, the MSE diagnostic is very sensitive to the plasma intrinsic radial electric field. This article describes a technique to measure Er involving the change of the polarization angle of the MSE emission, by using two beam injectors at different energies, firing sequentially. Experimental results for the low Er case, i.e., with very little plasma rotation, showing the ability of the MSE to perform this measurement, will be presented. This is the first time that evidence of a direct measurement of the plasma Er is reported from the Joint European Torus.
Free Keywords:Tokamak devices; plasma diagnostics; polarisation; electric field measurement; Stark effect; plasma turbulence; plasma transport processes
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Plasmaphysik/Tokamak Scenario Development (E1)
External Affiliations:Departamento de Física, Associação EURATOM/IST, Universidade da Beira Interior, 6200 Covilhã, Portugal; Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB, United Kingdom; Association Euratom/CEA, CEA-Cadarache, F-13108 St. Paul les Durance, France; Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543; Association Euratom-ENEA sulla Fusione, CRE Frascati, Roma, Italy; Associação EURATOM/IST, Centro de Fusão Nuclear, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; EFDA-JET, Culham Science Centre, OX14 3EA, United Kingdom
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