D. A. Mossessian P. Snyder A. Hubbard J. W. Hughes M. Greenwald et al.
For steady state high-confinement-mode (H-mode) operation, a relaxation mechanism is required to limit build-up of the edge gradient and impurity content. Alcator C-Mod [Hutchinson et al., Phys. Plasmas 1, 1511 (1994)] sees two such mechanisms—EDA (enhanced D-alpha H mode) and grassy ELMs (edge localized modes) , but not large type I ELMs. In EDA…
PublishedP. Helander D. J.Ward
It is shown that electron-positron pair production is expected to occur in post-disruption plasmas in large tokamaks, including JET and JT-60U, where up to about 10 14 positrons may be created in collisions between multi-MeV runaway electrons and thermal particles. If the loop voltage is large enough, they are accelerated and form a beam of long-li…
PublishedG. Manfredi C. M. Roach
The generation of zonal flows and their interplay with drift wave turbulence is studied numerically using a model based on the Hasegawa–Mima equation, with an electron response depending only on the fluctuating part of the electrostatic potential. In regimes dominated by the diamagnetic velocity, large-amplitude nonlinear oscillations are observe…
PublishedX. Garbet L. Garzotti P. Mantica H. Nordman M. Valovic H.Weisen C. Angioni
Particle transport in magnetized plasmas is investigated with a fluid model of drift wave turbulence. An analytical calculation shows that magnetic field curvature and thermodiffusion drive an anomalous pinch. The curvature driven pinch velocity is consistent with the prediction of turbulence equipartition theory. The thermodiffusion flux is found …
PublishedValeria T. G. Riccardo Philip L. Andrew Alan Sandford Kaye Peter Noll
In view of the modification to the Joint European Torus (JET) plasma facing components foreseen for the 2004 shutdown, the disruption design criteria for invessel components have been updated building on the operational experience with divertor plasmas gained since the early 1990s. In fast disruptions the largest contribution to the electromechanic…
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…
PublishedC. Hidalgo B. Goncálves C. Silva M. A. Pedrosa K. Erents M. Hron G. F. Matthews
The dynamical coupling between turbulent transport and parallel flows has been investigated in the plasma boundary region of the Joint European Torus tokamak. Experimental results show that there is a dynamical relationship between transport and parallel flows. As the size of transport events increases, parallel flows also increase. These results s…
PublishedPanos J Karditsas Neil P Taylor
As part of the European Power Plant Conceptual Study, two different divertor designs were proposed, based on previous work on HETS (High Efficiency Thermal Shield) performed at FZK and ENEA. The coolant is helium gas at pressures in the range 10-14 MPa and the inlet temperatures are in the range of 500-800 o C. The geometrical complexity of the des…
PublishedGhassan Y. Antar Glenn Counsell Yang Yu Brian Labombard Pascal Devynck
The nature of intermittency, long observed in magnetic fusion devices, was revisited lately [G. Antar et al. , Phys. Rev. Lett. 87 , 065001 (2001)]. It was shown that intermittency is caused by large-scale events with high radial velocity reaching about 1/10th of the sound speed. These type of structures were named ‘‘avaloids.’’ In the pres…
PublishedJ. B. Taylor
Ripples in the confining field may exert a torque on a rotating plasma. Time reversal symmetry implies that this torque should vanish for an ideal plasma. However, even in an apparently ideal plasma, singularities can give rise to a nonzero torque. This torque is evaluated for a simple configuration. Although the primary force is magnetic, an essen…
Published