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2006
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 …
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2006
Present day tokamaks are capable of generating toroidal flows approaching the ion sound speed. Such toroidal rotation is known to have a stabilising effect on resistive wall modes[1]. Here the effects of plasma rotation and diamagnetic drifts on the n = 1 internal kink mode and high n ballooning modes are presented with specific comparison to exper…
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2005
Alfven eigenmodes (AEs) are studied to assess their stability in high density reactor relevant regimes. Stable AEs are excited with active magnetohydrodynamics antennas in the range of the expected AE frequency. Toroidal Alfven eigenmode (TAE) damping rates have been observed in diverted and limited Ohmic plasmas. Energetic particle modes or TAEs h…
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2005
Self-consistent simulations of the International Thermonuclear Experimental Reactor (ITER) [R.Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)] have been carried out using the JETTO-integrated modeling code in which theory-motivated models are used for the H-mode pedestal and for the stability conditions that le…
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2004
A microwave interferometry technique is applied for the first time for detecting a discrete spectrum of Alfvén cascade (AC) eigenmodes excited with fast ions in reversed magnetic shear plasmas of the Joint European Torus. The interferometry measurements of plasma density perturbations associated with ACs show an unprecedented frequency and time re…
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2004
Experimental evidence is presented for the existence of the theoretically predicted odd toroidicity induced Alfve?n eigenmode (TAE) from the simultaneous appearance of odd and even TAEs in a normal shear discharge of the joint European torus. The modes are observed in low central magnetic shear plasmas created by injecting lower hybrid current driv…
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2004
The effects of nonresonating hot ions on the spectrum of magnetohydrodynamic (MHD) waves and instabilities in tokamaks are studied in the limit when the width of the hot ion drift orbits is much larger than the radial scale length of the MHD perturbations. Due to the large magnetic drift velocities the hot ions cannot contribute to the MHD perturb…
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2003
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…
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2002
Experiments on the JET tokamak show that the wave-induced pinch in the presence of toroidally asymmetric waves can provide a tool for controlling the profile of ion-cyclotron-resonant 3 He ions. Direct evidence for the wave-induced pinch has been obtained from the measured -ray emission profiles. Concurrent differences in the excitation of Alfve?n …
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2002
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…
Showing 61 - 70 of 74 UKAEA Paper Results