A. G. Peeters

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This contribution presents theoretical results on the transport of light and heavy impurities, as well as of energetic α particles, produced by the background electrostatic plasma turbulence. Linear and nonlinear simulations with three gyrokinetic codes, GS2, GYRO, and the recently developed GKW, are performed in concert with analytical derivations, in(More)
In this Letter, the influence of the "Coriolis drift" on small scale instabilities in toroidal plasmas is shown to generate a toroidal momentum pinch velocity. Such a pinch results because the Coriolis drift generates a coupling between the density and temperature perturbations on the one hand and the perturbed parallel flow velocity on the other. A simple(More)
The symmetry of a physical system strongly impacts on its properties. In toroidal plasmas, the symmetry along a magnetic field line usually constrains the radial flux of parallel momentum to zero in the absence of background flows. By breaking the up-down symmetry of the toroidal currents, this constraint can be relaxed. The parallel asymmetry in the(More)
Experiments were carried out in the JET tokamak to determine the critical ion temperature inverse gradient length (R/LTi=R|nablaTi|/Ti) for the onset of ion temperature gradient modes and the stiffness of Ti profiles with respect to deviations from the critical value. Threshold and stiffness have been compared with linear and nonlinear predictions of the(More)
The first experimental evidence of parallel momentum transport generated by the up-down asymmetry of a toroidal plasma is reported. The experiments, conducted in the Tokamak à Configuration Variable, were motivated by the recent theoretical discovery of ion-scale turbulent momentum transport induced by an up-down asymmetry in the magnetic equilibrium. The(More)
A study was carried out in the southern part of Switzerland (Canton Ticino) in 1990-1993 to determine the spectrum of cutaneous sensitivity to a large amount of pollens and several perennial allergens (50), using skin prick tests in a sample of 503 consecutive patients suffering from hay fever. The Canton Ticino is a very specific geographical and botanical(More)
Trapped electron modes are one of the candidates to explain turbulence driven electron heat transport observed in tokamaks. This instability has two characteristics: a threshold in normalized gradient and stabilization by collisions. Experiments using modulated electron cyclotron heating in the ASDEX Upgrade tokamak demonstrate explicitly the existence of(More)
In the theoretical description of the neoclassical tearing mode it is usually assumed that the ion banana width w(b) is much smaller than the island width W. This assumption is questionable at least for the island size at the mode onset. We show that a significant fraction of the (ion) bootstrap current survives inside the island when w(b) is comparable to(More)
Monte Carlo ion simulation based on neoclassical radial current balance in a divertor tokamak gives a stationary sheared E 3 B flow. The neoclassical radial electric field Er shows no bifurcation in contrast with earlier orbit loss models, but the shear in Er reaches values at which a transition to enhanced confinement has been observed. Also, MHD(More)