S.E. Sharapov B. Alper H.L. Berk D.N. Borba B.N. Breizman C.D. Challis I.G.J. Classen E.M. Edlund J. Eriksson A. Fasoli E.D. Fredrickson Et Al
Remarkable progress has been made in diagnosing energetic particle instabilities on present-day machines and in establishing a theoretical framework for describing them. This overview describes the much improved diagnostics of Alfven instabilities and modelling tools developed world-wide, and discusses progress in interpreting the observed phenomen…
PublishedS.E. Sharapov
A general introduction is given to ideal magnetohydrodynamic (MHD) waves, using linear perturbations of ideal MHD equations. Subsequently the shear Alfvén waves are shown to form a discrete spectrum of Global Alfvén Eigenmodes in current-carrying cylindrical plasmas and Toroidal Alfvén Eigenmodes in toroidal plasmas. A comparison between theory …
PublishedM.A. Van Zeeland W.W. Heidbrink R.K. Fisher M. García Muñoz, G.J. Kramer D.C. Pace R.B. White S. Aekaeslompolo M.E. Austin J.E. Boom I.G.J. Classen S. Da Graça B. Geiger M. Gorelenkova N. N. Gorelenkov A. W. Hyatt N. Luhmann M. Maraschek G. R. McKee R. A. Moyer C. M. Muscatello R. Nazikian H. Park S. Sharapov W. Suttrop G. Tardini B. J. Tobias Y. B. Zhu DIII-D and ASDEX Upgrade Teams
Neutral beam injection into reversed magnetic shear DIII-D and ASDEX Upgrade plasmas produces a variety of Alfvénic activity including toroidicity-induced Alfvén eigenmodes and reversed shear Alfvén eigenmodes (RSAEs). These modes are studied during the discharge current ramp phase when incomplete current penetration results in a high central sa…
PublishedS.E. Sharapov
Instabilities of Alfvén Eigenmodes (AEs) are often excited by a super-Alfvénic population of fast ions accelerated with ion cyclotron resonance heating (ICRH) or produced by neutral beam injection (NBI) in present-day tokamaks. In view of the next-step burning plasma experiments with super-Alfvénic alpha-particles, the experimental data on AE in…
PublishedM. K.Lilley B.N.Breizman S.E.Sharapov
A fully nonlinear model is developed for the bump-on-tail instability including the effects of dynamical friction drag and velocity space diffusion on the energetic particles driving the wave. The results show that drag provides a destabilizing effect on the nonlinear evolution of waves. Specifically, in the early nonlinear phase of the instability…
PublishedM. K. Lilley B. N. Breizman S. E. Sharapov
The nonlinear evolution of waves excited by the resonant interaction with energetic particles, just above the instability threshold, is shown to depend on the type of relaxation process that restores the unstable distribution function. When dynamical friction dominates over diffusion in the phase space region surrounding the wave-particle resonance…
PublishedS. E. Sharapov L.-G. Eriksson A. Fasoli G. Gorini J. Källne V. G. Kiptily A. A. Korotkov A. Murari S. D. Pinches D. S. Testa P. R. Thomas
Studies establishing key phenomena and developing diagnostics for energetic particle physics, which are essential for the next step burning plasma experiments such as the International Thermonuclear Experimental Reactor (ITER), have been performed at the Joint European Torus (JET). Experiments have demonstrated clear selfheating of deuterium-tritiu…
PublishedM. K. Lilley S. E. Sharapov
A discrete spectrum of compressional Alfvén eigenmodes and ion-ion hybrid eigenmodes is found to exist above the tritium ion cyclotron frequency in the deuterium-tritium D-T plasma of a spherical tokamak power plant STPP [H. R. Wilson and et al. , 19th IAEA Fusion Energy Conference IAEA, Lyon, France, (2002), No. FT/1-4]. An equilibrium magnetic w…
Published