1,721,827 research outputs found
EFD-P(13)16 Nonlinear Stabilization of Tokamak Microturbulence by Fast Ions
No full textJ. Citrin, F. Jenko, P. Mantica, D. Told, C. Bourdelle, J. Garcia, J.W. Haverkort, G.M.D. Hogeweij, T. Johnson, M.J. Pueschel and JET EFDA contributors Nonlinear electromagnetic stabilization by suprathermal pressure gradients found in specific regimes is shown to be a key factor in reducing tokamak microturbulence, augmenting significantly the thermal pressure electromagnetic stabilization. Based on nonlinear gyrokinetic simulations investigating a set of ion heat transport experiments on the JET tokamak, described by Mantica et al, this result explains the experimentally observed improved ion core confinement and stiffness reduction. These findings are expected to improve the extrapolation of advanced tokamak scenarios to reactor relevant regimes.Preprint of Paper to be submitted for publication in Physical Review Letter
Application of the RTP transport model to the JET tokamak
No full textThe peculiarities of the electron temperature profile under dominant on- and off-axis heating in RTF were successfully described by a 'shell model.' This model features electron transport barriers that are associated with simple rational values of the safety factor (G.M.D. Hogeweij et al., Nuc. Fusion 38, 1881 (1998)). This model is now tested against JET data. To this end, the model is incorporated in the JETTO code, which is used to simulate JET Optimized shear discharges with pronounced electron transport barriers. It is found that the model is successful in reproducing the time and location of barrier formation, as well as the subsequent evolution of barrier location and strength. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:3829.715695((01)01) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Almost-classical Lie algebras. I
No full textAbstractLet g be the Lie algebra of a semi-simple algebraic group G over an algebraically closed field k of characteristic p>0. In the first part of this paper we study the structure of g, and focus on the deviations from the characteristic 0 case. In the second part we determine, for almost-simple G, the automorphism group of g
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