J. Greenhough S.C. Chapman S. Chaty R.O. Dendy G. Rowlands
Whilst direct observations of internal transport in accretion disks are not yet possible, measurement of the energy emitted from accreting astrophysical systems can provide useful information on the physical mechanisms at work. Here we examine the unbroken multi-year time variation of the total X-ray flux from three sources: Cygnus X-1, the microqu…
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…
PublishedP. B. Snyder H. R. Wilson J. R. Ferron L. L. Lao A. W. Leonard et al.
A model based on magnetohydrodynamic (MHD) stability of the tokamak plasma edge region is presented, which describes characteristics of edge localized modes (ELMs) and the pedestal. The model emphasizes the dual role played by large bootstrap currents driven by the sharp pressure gradients in the pedestal region. Pedestal currents reduce the edge m…
PublishedR. J. Akers J. W. Ahn L. C. Appel E. R. Arends K. B. Axon et al.
Spontaneous transitions from the low ‘‘L-mode’’ to high ‘‘H-mode’’ of tokamak plasma confinement, first observed during neutral beam heating experiments on ASDEX, are now routinely achieved in many tokamak experiments. The H-mode regime is attractive as it offers the possibility of enhanced confinement, and thus a route towards a mo…
PublishedL. C. Ingesson D. J. Wilson
Aperture, pin-hole and collimator detection systems are often used in plasma diagnostics, for example, in soft x-ray detection and bolometer systems. In this article the simultaneous optimization of viewing-beam overlap and light yield is considered in multi-channel aperture and collimator systems for two-dimensional (2D)tomography. This article br…
PublishedCanh N. Nguyen Glenn Bateman Arnold H. Kritz Robert Akers Calum Byrom et al.
Integrated predictive modeling simulations are carried out using the BALDUR transport code [Singer et al. , Comput. Phys. Commun. 49 , 275 (1982)] for high confinement mode (H-mode) and low confinement mode (L-mode) discharges in the Mega-Amp Spherical Tokamak (MAST) [Sykes et al. , Phys. Plasmas 8 , 2101 (2001)]. Simulation results, obtained using…
PublishedA. K. Ram A. Bers C. N. Lashmore-Davies
In previous publications [A. K. Ram and S. D. Schultz, Phys. Plasmas 7 , 4084 (2000) ; A. Bers, A. K. Ram, and S. D. Schultz, in Proceedings of the Second Europhysics Topical Conference on RF Heating and Current Drive of Fusion Devices , edited by J. Jacquinot, G. Van Oost, and R. R. Weynants (European Physical Society, Petit-Lancy, 1998), Vol. 22A…
PublishedS. V. Annibaldi G. Manfredi R. O. Dendy
The transport of test particle ensembles moving in turbulent electrostatic fields governed by the Hasegawa–Mima equation is investigated. It ranges from subdiffusive to ballistic, depending on the size (in terms of thermal ion Larmor radii) of the domain considered, and on the magnitude of the background density gradient. In addition to the elect…
PublishedR. J. Akers G. F. Counsell A. Sykes L. C. Appel E. R. Arends C. Byrom P. G. Carolan N. J. Conway G. Cunningham A. Dnestrovskij Yu.N. Dnestrovskij A. R. Field S. J. Fielding M. Gryaznevich P. Helander A. Kirk S. Korsholm R. Martin H. Meye
H -mode plasmas have been achieved on the MAST spherical tokamak at input power considerably higher than predicted by conventional threshold scalings. Following L - H transition, a clear improvement in energy confinement is obtained, exceeding recent international scalings even at densities approaching the Greenwald density limit. Transition is acc…
Published