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2004
A microwave interferometry technique is applied for the first time for detecting a discrete spectrum of Alfvén cascade (AC) eigenmodes excited with fast ions in reversed magnetic shear plasmas of the Joint European Torus. The interferometry measurements of plasma density perturbations associated with ACs show an unprecedented frequency and time re…
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2004
Gyrokinetic microstability analyses, with and without electromagnetic effects, are presented for a spherical tokamak plasma equilibrium closely resembling that from a high confinement mode ( H mode ) discharge in the mega-ampere spherical tokamak ( MAST ) [ A. Sykes et al. , Nucl. Fusion 41 , 1423 ( 2001 )] . Electrostatic ion temperature gradient …
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2004
Previous observations that suggest a substantial role for nondiffusive energy transport in tokamaks subjected to off-axis electron cyclotron heating (ECH) are compared to the output from a sandpile model. The observations considered include local and global aspects of temperature profile evolution in the DIII-D [for example, C. C. Petty and T. C. L…
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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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2004
Direct numerical simulations of electron dynamics in externally driven electrostatic waves have been carried out using a relativistic two-fluid one-dimensional Vlasov–Poisson code. When the driver wave has sufficiently large amplitude, ion density holes ( cavitons ) form. The interaction between these cavitons and other incoming Langmuir waves gi…
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2004
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2004
The time evolution of edge localized modes ( ELMs ) in the Joint European Torus tokamak [ P. H. Rebut and et al. , Nucl. Fusion 25 , 1011 ( 1985 )] is investigated using the JETTO predictive modeling code [ M. Erba and et al. , Plasma Phys. Controlled Fusion 39 , 261 ( 1997 )] . It is found that both pressure-driven ballooning and current-driven pe…
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2004
The effects of nonresonating hot ions on the spectrum of magnetohydrodynamic (MHD) waves and instabilities in tokamaks are studied in the limit when the width of the hot ion drift orbits is much larger than the radial scale length of the MHD perturbations. Due to the large magnetic drift velocities the hot ions cannot contribute to the MHD perturb…
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2004
The identification of preacceleration mechanisms for cosmic ray ions in supernova remnant shocks is an important problem in astrophysics. Recent particle-in-cell ( PIC ) shock simulations have shown that inclusion of the full electron kinetics yields non-time-stationary solutions, in contrast to previous hybrid ( kinetic ions, fluid electrons ) sim…
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2004
A tokamak’s economic performance is strongly affected by the plasma pressure that it may sustain, which in turn is limited by the maximum pressure gradients that may be supported. Ballooning modes are typically driven unstable by increasing the pressure gradient, and because they can radially extend across many rational surfaces, they can serious…
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