title: Synergy of electron-cyclotron and lower-hybrid current drive in steady-state plasmas.
abstract: Improvement (up to a factor of approximately 4) of the electron-cyclotron (EC) current drive efficiency in plasmas sustained by lower-hybrid (LH) current drive has been demonstrated in stationary conditions on the Tore Supra tokamak. This was made possible by feedback controlled discharges at zero loop voltage, constant plasma current, and constant density. This effect, predicted by kinetic theory, results from a favorable interplay of the velocity space diffusions induced by the two waves: the EC wave pulling low-energy electrons out of the Maxwellian bulk, and the LH wave driving them to high parallel velocities.
authors.affiliation: Association Euratom-CEA, CEA/DSM/DRFC, CEA/Cadarache, 13108 St. Paul-lez-Durance, France.
authors.forename: G
authors.initials: G
authors.lastname: Giruzzi
authors.forename: J F
authors.initials: JF
authors.lastname: Artaud
authors.forename: R J
authors.initials: RJ
authors.lastname: Dumont
authors.forename: F
authors.initials: F
authors.lastname: Imbeaux
authors.forename: P
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authors.lastname: Bibet
authors.forename: G
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authors.lastname: Berger-By
authors.forename: F
authors.initials: F
authors.lastname: Bouquey
authors.forename: J
authors.initials: J
authors.lastname: Clary
authors.forename: C
authors.initials: C
authors.lastname: Darbos
authors.forename: A
authors.initials: A
authors.lastname: Ekedahl
authors.forename: G T
authors.initials: GT
authors.lastname: Hoang
authors.forename: M
authors.initials: M
authors.lastname: Lennholm
authors.forename: P
authors.initials: P
authors.lastname: Maget
authors.forename: R
authors.initials: R
authors.lastname: Magne
authors.forename: J L
authors.initials: JL
authors.lastname: Ségui
authors.forename: A
authors.initials: A
authors.lastname: Bruschi
authors.forename: G
authors.initials: G
authors.lastname: Granucci