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…
PublishedG. J. Kramer R. Nazikian B. Alper M. De Baar H. L. Berk G.-Y. Fu N. N. Gorelenkov G. Mckee S. D. Pinches T. L. Rhodes S. E. Sharapov W. M. Solomon M. A. Van Zeeland JET EFDA Contributors
Reversed shear Alfvén eigenmodes RSAE that were observed in the Joint European Torus (JET) [P. H. Rebut and B. E. Keen, Fusion Technol. 11 , 13 (1987)] and DIII-D [J. L. Luxon, Nucl. Fusion 42 , 614 (2002)] are studied with the ideal magnetohydrodynamic code NOVA-K C. [Z. Cheng, Phys. Rep. 211 , 1 (1992)]. It was found that the frequency behavior …
PublishedB. N. Breizman H. L. Berk M. S. Pekker S. D. Pinches S. E. Sharapov
Plasma configurations with shear reversal are prone to the excitation of unusual Alfven eigenmodes by energetic particles. These modes exhibit a quasiperiodic pattern of predominantly upward frequency sweeping ( Alfven cascades ) as the safety factor q changes in time. This work presents a theory that employs two complementary mechanisms for establ…
PublishedS. E. Sharapov B. Alper H. L. Berk D. N. Borba B. N. Breizman et al.
Experiments designed for generating internal transport barriers in the plasmas of the Joint European Torus [JET, P. H. Rebut et al. , Proceedings of the 10th International Conference, Plasma Physics and Controlled Nuclear Fusion, London ~ International Atomic Energy Agency, Vienna, (1985), Vol. I, p. 11 ] reveal cascades of Alfven perturbations wit…
PublishedH. L. Berk D. N. Borba B. N. Breizman S. D. Pinches S. E. Sharapov
Alfvén spectra in a reversed-shear tokamak plasma with a population of energetic ions exhibit a quasiperiodic pattern of primarily upward frequency sweeping (Alfvén cascade). Presented here is an explanation for such asymmetric sweeping behavior which involves finding a new energetic particle mode localized around the point of zero magnetic shear…
Published