P. Helander T. Fülöp M. Lisak
It is shown that poloidally asymmetric particle transport or fueling in a tokamak generally produces an electric current parallel to the magnetic field, in particular if the transport or fueling is up-down asymmetric. For instance, a current arises in the edge region if most particle transport across the last closed flux surface occurs in the midpl…
PublishedD. Nguyen-Manh A. P. Horsfield S. L. Dudarev
We present an investigation of systematic trends for the self-interstitial atom SIA defect behavior in body-centered cubic bcc transition metals using density-functional calculations. In all the nonmagnetic bcc metals the most stable SIA defect configuration has the 111 symmetry. Metals in group 5B of the periodic table V, Nb, Ta have significantly…
PublishedC. G. Gimblett R. J. Hastie P. Helander
Edge-localized modes (ELMs) are cyclic disturbances in the outer region of tokamak plasmas that are influential in determining present and future tokamak performance. In this Letter, we outline an approach to modeling ELMs in which we envisage toroidal peeling modes initiating a Taylor relaxation [Phys. Rev. Lett. 33 , 1139 (1974)] of a tokamak out…
PublishedD. A. Murdick X. W. Zhou H. N. G. Wadley D. Nguyen-Manh R. Drautz D. G. Pettifor
An analytic, bond-order potential BOP is proposed and parametrized for the gallium arsenide system. The potential addresses primary and secondary bonding and the valence-dependent character of heteroatomic bonding, and it can be combined with an electron counting potential to address the distribution of electrons on the GaAs surface. The potential …
PublishedP. Mantica D. Van Eester X. Garbet F. Imbeaux L. Laborde M. Mantsinen A. Marinoni D. Mazon D. Moreau N. Hawkes E. Joffrin V. Kiptily S. Pinches A. Salmi S. Sharapov A. Thyagaraja I. Voitsekhovitch P. De Vries K.-D. Zastrow
The first electron temperature modulation experiments in plasmas characterized by strong and longlasting electron and ion internal transport barriers (ITB) have been performed in JET using ion cyclotron resonance heating in mode conversion scheme. The ITB is shown to be a well localized narrow layer with low heat diffusivity, characterized by subcr…
PublishedJ. A. Merrifield T. D. Arber S. C. Chapman R. O. Dendy
Understanding the phenomenology captured in direct numerical simulation (DNS) of magnetohydrodynamic (MHD) turbulence rests upon models and assumptions concerning the scaling of field variables and dissipation. Here compressible MHD turbulence is simulated in two spatial dimensions by solving the isothermal equations of resistive MHD on a periodic …
PublishedB. Goncalves C. Hidalgo M. A. Pedrosa R. O. Orozco E. Sanchez C. Silva
Radial profiles of the parallel-radial Reynolds stress component, proportional to the cross correlation between parallel and radial fluctuating velocities, have been measured in the plasma boundary region of the TJ-II stellarator. Experimental results show the existence of significant parallel turbulent forces at plasma densities above the threshol…
PublishedS. Newton P. Helander
It is widely believed that transport barriers in tokamak plasmas are caused by radial electric-field shear, which is governed by angular momentum transport. Turbulence is suppressed in the barrier, and ion thermal transport is comparable to the neoclassical prediction, but experimentally angular momentum transport has remained anomalous. With this …
PublishedA. Kirk B. Koch R. Scannell H. R. Wilson G. Counsell J. Dowling A. Herrmann
Edge-localized modes (ELMs) are repetitive instabilities that occur in the outer region of tokamak plasmas. This Letter provides new information on and the implications of the evolution of the filament structures observed during ELMs in the MAST tokamak. The filaments exist for the time over which particles are being released into the scrape off la…
PublishedM. F. F. Nave H. R. Koslowski S. Coda J. Graves M. Brix R. Buttery C. Challis C. Giroud M. Stamp P. De Vries Jet-Feda Contributors
During a recent reversed toroidal field (B T) campaign at the Joint European Torus (JET), experiments were performed to investigate the effect on sawteeth of neutral beam injection (NBI)-driven toroidal plasma rotation counter to the direction of the toroidal plasma current and B T . A power scan at constant density has permitted analytical continu…
Published