Henderson, M. A.Alberti, S.Angioni, C.Arnoux, G.Behn, R.Blanchard, P.Bosshard, P.Camenen, Y.Coda, S.Condrea, I.Goodman, T. P.Hofmann, F.Hogge, J.-Ph.Karpushov, A.Manini, A.Martynov, An.Moret, J.-M.Nikkola, P.Nelson-Melby, E.Pochelon, A.Porte, L.Sauter, O.Ahmed, S. M.Andrèbe, Y.Appert, K.Chavan, R.Degeling, A.Duval, B. P.Etienne, P.Fasel, D.Fasoli, A.Favez, J.-Y.Furno, I.Horacek, J.Isoz, P.Joye, B.Klimanov, I.Lavanchy, P.Lister, J. B.Llobet, X.Magnin, J.-C.Marlétaz, B.Marmillod, P.Martin, Y.Mayor, J.-M.Mylnar, J.Paris, P. J.Perez, A.Peysson, Y.Pitts, R. A.Raju, D.Reimerdes, H.Scarabosio, A.Scavino, E.Seo, S. H.Siravo, U.Sushkov, A.Tonetti, G.Tran, M. Q.Weisen, H.Wischmeier, M.Zabolotsky, A.Yhuang, G.2008-04-182008-04-182008-04-18200310.1063/1.15621672-s2.0-0038025409https://infoscience.epfl.ch/handle/20.500.14299/23321WOS:000182450200036In noninductively driven discharges, 0.9 MW second harmonic (X2) off-axis co-electron cyclotron current drive deposition is combined with 0.45 MW X2 central heating to create an electron internal transport barrier (eITB) in steady plasma conditions resulting in a 1.6-fold increase of the confinement time (tau(Ee)) over ITER-98L-mode scaling. The eITB is associated with a reversed shear current profile enhanced by a large bootstrap current fraction (up to 80%) and is sustained for up to 10 current redistribution times. A linear dependence of the confinement improvement on the product of the global shear reversal factor (q(0)/q(min)) and the reversed shear volume (rho(q-min)(2)) is shown. In other discharges heated with X2 the sawteeth are destabilized (respectively stabilized) when heating just inside (respectively outside) the q=1 surface. Control of the sawteeth may allow the avoidance of neoclassical tearing modes that can be seeded by the sawtooth instability. Results on H-mode and highly elongated plasmas using the newly completed third harmonic (X3) system and achieving up to 100% absorption are also discussed, along with comparison of experimental results with the TORAY-GA ray tracing code [K. Matsuda, IEEE Trans. Plasma Sci. PS-17, 6 (1989); R. H. Cohen, Phys. Fluids 30, 2442 (1987)]. (C) 2003 American Institute of Physics.ITERtext::journal::journal article::research article