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2003
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…
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2001
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…
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2000
The edge-localized, high-confinement mode regime is of interest for future Tokamak reactors since high performance has been sustained for long durations. Experiments in the Joint European Tokamak [M. Keilhacker et al. , Nuclear Fusion 39 , 209 (1999)] have studied this regime using scans with the toroidal field and plasma current varied together in…
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1999
There is increasing evidence that the Earth’s magnetosphere, like other macroscopic confined plasma systems (magnetic fusion plasmas, astrophysical accretion discs), displays sandpile-type phenomenology so that energy dissipation is by means of avalanches which do not have an intrinsic scale. This may in turn imply that these systems evolve via s…
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1995
To gain insight into divertor operation, similarity techniques are employed to investigate whether model systems of equations plus boundary conditions admit scaling transformations that lead to useful divertor scaling laws. These can be used to perform similarity experiments or more fully exploit large computer simulations. Fluid plasma models of t…
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1995
An Eulerian code that solves the gyrokinetic Vlasov equation in slab geometry is presented. It takes into account the E X B and polarization drifts in the plane perpendicular to the magnetic field, and kinetic effects in the parallel direction. The finite Larmor radius is modelled by a convolution operator. The relation is established between this …
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1994
An interferometer with compensation for vibration and large scale mechanical movements has been designed and built to measure the line integral electron density along three different lines of sight through the JET divertor plasma. Overcoming the effects of a long transmission path, having an estimated 65 dB loss, requires oversized waveguide transm…
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1991
The purpose of this paper is to investigate the possible relationships between transport properties such as thermal diffusivity and resistivity on the one hand, and the magnetic properties such as q profile and toroidal flux change on the other, in tokamaks that exist under macroscopically quasistationary conditions. It is experimentally well estab…
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1990
The set of semicollisional layer equations derived by Fitzpatrick [Phys. Fluids B 1, 2381 (1989)] is used to investigate the effect of trapped particles on the linear stability of long wavelength resistive modes in a large-aspect-ratio tokamak. At 0( 1) shear, destabilization by trapped particles is found to significantly modify previous cylindrica…
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