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1996
Crystal and synthetic multilayer diffractors, deployed either as flat Bragg reflectors, or curved, as in the Johann configuration, are used to study the spectrum of COMPASS-D and other tokamaks in the wavelength region of 1–100 A. In this article, we concentrate on the measurement of absolute photon fluxes and the derivation of volume emissivitie…
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1996
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1996
Test-particle transport arising from E 3 B motion in a turbulent plasma is investigated numerically. The electrostatic field is determined by solving the Hasegawa-Mima model for two-dimensional drift turbulence. In the linear regime the particles experience stochastic diffusion, but in the fully nonlinear, strongly turbulent regime the diffusion ra…
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1996
Edge plasmas, such as the tokamak scrape-off layer, exist as a consequence of a balance between cross-field diffusion and parallel losses. The former is usually anomalous, and is widely thought to be driven by strong electrostatic turbulence. It is shown that the anomalous diffusion affects the parallel ion transport by giving rise to a new type of…
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1996
In a fusion plasma ion cyclotron heating may be applied to a plasma in a regime where there is a population of ions whose Larmor radius is not small compared to the perpendicular wavelength. In this case the equations describing the propagation and absorption of the wave are integro-differential, describing the non-local response of the plasma to t…
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1996
The propagation of the ion hybrid wave in a deuteriumtritium plasma and in the presence of a small population of fusion alphaparticles is analysed. A non-thermal distribution of alpha-particles is considered which is relevant to their distribution before they have slowed down. Non-thermal distributions are also relevant to large excursion orbit alp…
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1996
The fast wave approximation, extended to include the effects of electron dissipation, is used to calculate the power mode converted to the ion hybrid (Bernstein) wave in the vicinity of the ion hybrid resonance. The power absorbed from the fast wave by ion cyclotron damping and by electron Landau and transit time damping (including cross terms) is …
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1995
A theory for the existence of noninteracting small-scale, "drift" magnetic islands in a high temperature tokamak plasma is presented. This situation contrasts with that discussed by Rebut and Hugon [Plasma Phys. Controlled Fusion 33, 1085 (1991)] which involves a background "sea" of magnetic turbulence caused by island overlap. The islands are driv…
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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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1995
A kinetic theory for magnetic islands in a low collision frequency tokamak plasma is presented. Self-consistent equations for the islands’ width, w , and propagation frequency, w , are derived. These include contributions from the perturbed bootstrap current and the toroidally enhanced ion polarization drift. The bootstrap current is ind…
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