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Recent results from the electron cyclotron heated plasmas in Tokamak à Configuration Variable (TCV)

2003; American Institute of Physics; Volume: 10; Issue: 5 Linguagem: Inglês

10.1063/1.1562167

1527-2419

M. Henderson, S. Alberti, C. Angioni, G. Arnoux, R. Behn, P. Blanchard, P. Bosshard, Y. Camenen, S. Coda, I. Condrea, T. Goodman, F. Hofmann, J.-P. Hogge, A. Karpushov, A. Manini, An. Martynov, J.M. Moret, P. Nikkola, E. Nelson-Melby, A. Pochelon, L. Porte, O. Sauter, S. M. Ahmed, Y. Andrèbe, K. Appert, R. Chavan, A. W. Degeling, B.P. Duval, P. Étienne, D. Fasel, A. Fasoli, J.-Y. Favez, I. Furno, J. Horáček, P.-F. Isoz, B. Joye, I. Klimanov, P. Lavanchy, J.B. Lister, X. Llobet, J.-C. Magnin, B. Marlétaz, Ph. Marmillod, Yves Martin, J.-M. Mayor, J. Mylnar, P. Paris, A. Pérez, Y. Peysson, R.A. Pitts, D. Raju, H. Reimerdes, A. Scarabosio, Edgar Scavino, Seong-Heon Seo, U. Siravo, A. V. Sushkov, G. Tonetti, Quang Tran Minh, H. Weisen, M. Wischmeier, A. Zabolotsky, G. Yhuang,

Laser-Plasma Interactions and Diagnostics

In 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 (τEe) 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 (q0/qmin) and the reversed shear volume (ρq-min2) 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)].