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2005
The interpretation of EBW emission from spherical tokamaks is nontrivial. We report on a 3D simulation model of this process that incorporates Gaussian beams for the antenna, a full wave solution of EBW-X and EBW-X-O conversions using adaptive finite elements, and EBW ray tracing to determine the radiative temperature. This model is then used to in…
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2004
An investigation is presented of the effect of an error field on the growth of a resistive wall mode (RWM). This issue is of importance to many toroidal confinement devices, but particularly to the proposed International Thermonuclear Experimental Reactor (ITER) [ITER Physics Basis, Nucl. Fusion 39 , 2175 (1999)], where if advanced tokamak performa…
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2003
Ripples in the confining field may exert a torque on a rotating plasma. Time reversal symmetry implies that this torque should vanish for an ideal plasma. However, even in an apparently ideal plasma, singularities can give rise to a nonzero torque. This torque is evaluated for a simple configuration. Although the primary force is magnetic, an essen…
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2003
The existing regulatory framework in France provides a full and coherent licensing basis to permit ITER to be build and operated at Cadarache. The specific sitting studies including the submission of the first step of licensing documentation for ITER offers an early assessment of fusion power plants. The regulatory procedure begins with the release…
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2003
As part of the European Power Plant Conceptual Study, two different divertor designs were proposed, based on previous work on HETS (High Efficiency Thermal Shield) performed at FZK and ENEA. The coolant is helium gas at pressures in the range 10-14 MPa and the inlet temperatures are in the range of 500-800 o C. The geometrical complexity of the des…
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2002
Spontaneous acceleration of ions to suprathermal energies is observed during magnetic reconnection in the Mega-Ampere Spherical Tokamak (MAST). A high-energy tail is observed in the iondistribution function following each internal reconnection event in Ohmic discharges. This phenomenon is explained in terms of runaway ion acceleration in the electr…
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2001
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…
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2000
The finite resistivity of the wall that surrounds any toroidal plasma confinement device can lead to a branch of instabilities known as the resistive wall mode (RWM). Theory indicates that the RWM is potentially activated whenever the plasma equilibrium is unstable with the wall placed at infinity. In particular, advanced tokamak power plant design…
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2000
A model is developed to analyze the stabilization of the resistive wall mode (RWM) by plasma rotation. Central to the model is a cylindrical plasma that is ideal magnetohydrodynamic unstable in the absence of a wall, and possesses an internal resonance [J. M. Finn, Phys. Plasmas 2 , 198 (1995)]. This system is then a qualitative model for the actua…
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2000
Relaxation is the result of turbulence in a plasma that behaves essentially as an ideal conducting fluid, but has a small resistivity and viscosity. These small effects are locally enhanced by the turbulence and lead to reconnection of magnetic field lines. This destroys an infinity of topological constraints, leaving only the total magnetic helici…
Showing 101 - 110 of 123 UKAEA Paper Results