N. C. Woolsey Y. Abou Ali R. G. Evans R. A. D. Grundy S. J. Pestehe et al.
The VULCAN [C. N. Danson et al. , Opt. Commun. 103 , 392 (1993)] laser at the UK Central Laser Facility is being used for laboratory-based simulations of collisionless shocks. By ensuring that key dimensionless parameters in the experiments have values similar to those of supernova remnants (SNRs), the hydrodynamics and magnetic field of the experi…
PublishedG. T. A. Huysmans T. C. Hender N. C. Hawkes X. Litaudon
A region of zero current density in the plasma center has been observed in the advanced tokamak scenarios with off-axis lower-hybrid current drive in the JET and JT-60U tokamak experiments. Significantly, the central current density does not become negative, although this is expected based on conventional current diffusion. In this paper, it is sho…
PublishedJ. W. Connor F. L. Waelbroeck H. R. Wilson
The polarization current plays an important role in the evolution of magnetic islands with a width comparable to the characteristic ion orbit width. Understanding the evolution of such small magnetic islands is important for two reasons: (1) to investigate the threshold mechanisms for growth of large-scale islands (e.g., neoclassical tearing modes)…
PublishedK. G. McClements M. E. Dieckmann A. Ynnerman S. C. Chapman R. O. Dendy
The surfatron offers the possibility of particle acceleration to arbitrarily high energies, given a sufficiently large system. Surfatron acceleration of electrons by waves excited by ions reflected from supernova remnant (SNR) shocks is investigated using particle simulations. It is shown that surfatron and stochastic acceleration could provide a s…
PublishedT. Fülöp P. Helander
In conventional neoclassical theory, the density and temperature gradients are not allowed to be as steep as frequently observed in the tokamak edge. In this paper the theory of neoclassical transport in a collisional, impure plasma is extended to allow for steeper profiles than normally assumed. The dynamics of highly charged impurity ions then be…
PublishedS. Günter A. Gude M. Maraschek S. Sesnic H. Zohm Asdex Upgrade Team D. F. Howell
High confinement [with H 1 , ITERH- 98 y, 2 ] at b N 2.3 has been found in ASDEX Upgrade discharges with existing m, n 3, 2 neoclassical tearing modes (NTMs). The reason for the high confinement at high b N values is a transition of the NTMs into the so-called frequently interrupted regime. In this regime, the NTM growth is frequently interrupted b…
PublishedJ. B. Taylor J. W. Connor C. G. Gimblett H. R. Wilson R. J. Hastie
The resistive wall mode ~ RWM ! poses a threat to many plasma confinement devices. The continuous rotation of the wall relative to the plasma makes it appear perfectly conducting, because of the skin effect, but this is ineffective if the perturbation locks to the wall. This raises the question of whether a nonuniformly rotating wall is more effect…
PublishedR. J. La Haye R. J. Buttery S. Guenter G. T. A. Huysmans M. Maraschek et al.
The islands from tearing modes driven unstable and sustained by the helically perturbed neoclassical bootstrap current often provide the practical limit to long-pulse, high confinement tokamak operation. The destabilization of such ‘‘metastable’’ plasmas depends on a ‘‘seed’’ island exceeding a threshold. A database from similar reg…
PublishedS. L. Dudarev
The origin of the effect of inhomogeneous swelling observed near grain boundaries in irradiated materials is examined taking into account both nucleation and diffusional growth of cavities, and the interaction of cavities with mobile interstitial clusters produced in collision cascades. The model shows the formation of a characteristic profile of i…
Published