1. Lower Hybrid Current Drive in Tore Supra and Jet
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Moreau, D., Gormezano, C., Agarici, G., Agostini, E., Ane, J. M., Auge, N., Balme, S., Basiuk, V., Bareyt, B., Bayetti, P., Beaumont, B., Becherer, R., Becoulet, A., Benkadda, M., Bergerby, G., Bessette, D., Bibet, P., Bizarro, J. P., Bonmardion, G., Bonnel, P., Bottereau, J. M., Bottiglioni, F., Brugnetti, R., Bruneau, J. L., Buravand, Y., Capes, H., Capitain, J. J., Chappuis, P., Chatain, D., Chatelier, A., Chatelier, M., Ciazynski, D., Cordier, J. J., Coston, J. F., Coulon, J. P., Couturier, B., Crenn, J. P., Deck, C., Degentile, B., Demarthe, H., Demichelis, C., Deschamps, P., Devynck, P., Doceul, L., Dougnac, M., Drawin, H. W., Dubois, M., Duchateau, J. L., Dupas, L., Edery, D., Elbeze, D., Evans, T., Fall, T., Farjon, J. L., Fidone, I., Fois, M., Foster, C. A., Fumelli, M., Gagey, B., Garbet, X., Gauthier, E., Geraud, A., Gervais, F., Gendrih, P., Gil, C., Giruzzi, G., Goniche, M., Gravier, R., Gravil, B., Gregoire, M., Gresillon, D., Grisolia, C., Grosman, A., Guilhem, D., Guillerminet, B., Hennequin, P., Hennion, F., Hertout, P., Hess, W. R., Hesse, M., Hoang, G. T., Horton, L., Hubbard, A., Hutter, T., Idmtal, J., Jacquot, C., Jager, B., Javon, C., Jequier, F., Joffrin, E., Johner, J., Journeaux, J. Y., Joyer, P., Kuus, H., Lafon, D., Lasalle, J., Laurent, L., Laviron, C., Leclert, G., Lecoustey, P., Leloup, C., Libeyre, P., Lipa, M., Litaudon, X., Loarer, T., Lotte, P., Magaud, P., Magne, R., Martin, G., Martinez, A., Maschke, E. K., Mattioli, M., Mayaux, G., Mioduszewski, P., Misguich, J., Moniergarbet, P., Morera, J. P., Moret, J. M., Moulin, B., Moulin, D., Mourguesmillot, F., Moustier, M., Nguyen, F., Olivain, J., Ouvrierbuffet, P., Pamela, J., Panzarella, A., Parlange, F., Pastor, G., Patris, R., Paume, M., Pecquet, A. L., Pegourie, B., Peysson, Y., Piat, D., Picchiottino, J. M., Pierre, J., Platz, P., Portafaix, C., Poutchy, F., Prou, M., Quemeneur, A., Rax, J. M., Rey, G., Riband, P., Rigaud, D., Rodriguez, L., Rothan, B., Roubin, J. P., Roussel, P., Saha, S. K., Samaille, F., Samain, A., Saoutic, B., Schlosser, J., Seigneur, A., Segui, J. L., Shepard, T., Soler, K., Stirling, W., Tachon, J., Talvard, M., Tonon, G., Torossian, A., Truc, A., Turck, B., Uckan, T., Vallet, J. C., Vanhoutte, D., Weisse, J., and Zou, X. L.
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JET - Abstract
Recent Lower Hybrid Current Drive (LHCD) experiments in TORE SUPRA and JET are reported. Large multijunction launchers have allowed the coupling of 5 MW to the plasma for several seconds with a maximum of 3.8 kw/cm2. Measurements of the scattering matrices of the antennae show good agreement with theory. The current drive efficiency in TORE SUPRA is about 0.2 x 10(20) Am-2/W with LH power alone and reaches 0.4 x 10(20) Am-2/W in JET thanks to a high volume-averaged electron temperature (1.9 keV) and also to a synergy between Lower Hybrid and Fast Magnetosonic Waves. At N(e)BAR = 1.5 x 10(19) m-3 in TORE SUPRA, sawteeth are suppressed and m = 1 MHD oscillations the frequency of which clearly depends on the amount of LH power are observed on soft x-rays, and also on non-thermal ECE. In JET ICRH produced sawtooth-free periods are extended by the application of LHCD (2.9 s. with 4 MW ICRH) and current profile broadening has been clearly observed consistent with off-axis fast electron populations. LH power modulation experiments performed in TORE SUPRA at N(e)BAR = 4 x 10(19) m-3 show a delayed central electron heating despite the off-axis creation of suprathermal electrons, thus ruling out the possibility of a direct heating through central wave absorption. A possible explanation in terms of anomlous fast electron transport and classical slowing down would yield a diffusion coefficient of the order of 10 m2/s for the fast electrons. Other interpretations such as an anomalous heat pinch or a central confinement enhancement cannot be excluded. Finally, successful pellet fuelling of a partially LH driven plasma was obtained in TORE SUPRA, 28 successive pellets allowing the density to rise to N(e)BAR = 4 x 10(19) m-3. This could be achieved by switching the LH power off for 90 ms before each pellet injection, i.e. without modifying significantly the current density profile.