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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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1999
It has been suggested [Kleva and Guzdar, Phys. Plasmas 6 , 116 (1999)] that reconnecting ballooning modes in which electron inertia replaces resistivity in a nonideal magnetohydrodynamic Ohm’s law can have substantial growth rates in the low collisionality regime. Numerical calculation, albeit necessarily at unrealistically large values of the co…
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1999
The possibility of stabilizing ideal magnetohydrodynamical (MHD) instabilities by resistive walls and slow plasma rotation (rotation frequencies comparable to resistive tearing growth rates) was proposed recently by Finn [Phys. Plasmas 2 , 3782 (1995)] on the basis of cylindrical theory. In the present paper we analyze toroidal effects (pressure gr…
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1999
The peeling mode restricts access to the second stability region of the ideal ballooning mode at the tokamak plasma edge. Using a two-dimensional, high toroidal mode number eigenmode code employing a model tokamak equilibrium, it is shown that a window to second stability exists for a sufficiently deep magnetic well. The different mode structures o…
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1999
The electron cyclotron emission ~ECE! diagnostic system is installed on the large helical device ~LHD!. The system includes the following instruments: a heterodyne radiometer, a Michelson spectrometer, and a grating polychromator. A 63.5 mm corrugated waveguide system is fully utilized. Large collection optics and notch filters at the frequency of …
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1999
An empirical procedure, ‘‘LINT,’’ for relating emission line intensities of intrinsic impurity ions to their elemental contributions to the total, bolometric, radiation loss and the volume-averaged effective ion charge, Zeff , has been developed and applied to limiter plasmas in the JET tokamak. In this article we discuss extensions to the …
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1999
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1999
The polarimeter system for ITER features 10 viewing chords covering almost the full poloidal cross section of the plasma in a fan-like arrangement. The 10 laser beams all enter the plasma via 150 mm diam penetrations through the diagnostic plug at the low-field side. Small retroreflectors at the high-field side mirror the laser beams back towards t…
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1999
A simple one-dimensional sandpile model is constructed which possesses exact analytical solvability while displaying both scale-free behavior and fractal properties. The sandpile grows by avalanching on all scales, yet its shape and energy content are described by a simple, continuous (but nowhere differentiable) analytical formula. The avalanche e…
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1999
The ideal magnetohydrodynamic (MHD) stability of the tokamak edge is analyzed, with particular emphasis on radially localized instabilities; it is proposed that these are responsible for edge pressure gradient limits and edge localized modes (ELMS). Data and stability calculations from DIII-D [to appear in Proceedings of the 16th International Conf…
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