Results 191 to 200 of about 892 (228)

Neoclassical Transport Properties of Tokamak Plasmas

Fusion Science and Technology, 2004
The classical transport theory is strictly valid for a plasma in a homogeneous and stationary magnetic field. In the '60, experiments have shown that this theory does not apply as a local theory of transport in Tokamaks. It was shown that global geometric characteristics of the confining elements have a strong influence on the transport.
openaire   +6 more sources

Thermodynamics of neoclassical and turbulent transport

Plasma Physics and Controlled Fusion, 2012
A variational principle based on the calculation of the entropy production rate is derived, which covers particle, momentum and heat transport. This principle is used to define proper thermodynamical forces and fluxes. When turbulent parallel wavenumbers are small, and fluctuations are ballooned, it is found that the forces are the gradients of density,
Garbet X., Abiteboul J., Strugarek A., Sarazin Y., Dif-Pradalier G., Ghendrih P., Grandgirard V., Bourdelle C., Latu G., Smolyakov A.   +9 more
openaire   +1 more source

Neoclassical ripple transport in tokamaks

Nuclear Fusion, 1982
The usual ripple transport calculations lead to a ν−1 scaling of the transport coefficients with collision frequency ν. The paper extends and clarifies this scaling by taking into account the fact that the dominant contributions to transport come from particles in the high-energy tail of the distribution function.
K.C. Shaing, J.D. Callen
openaire   +1 more source

Bifurcated neoclassical particle transport

Physics of Plasmas, 1998
The theory of neoclassical transport in an impure, toroidal plasma is extended to allow for steeper pressure and temperature gradients than are usually considered. It is found that the ion particle flux is a nonmonotonic function of these gradients for plasma parameters typical of the tokamak edge.
openaire   +1 more source

Monte-Carlo simulation of neoclassical transport in stellarators

Nuclear Fusion, 1984
Neoclassical transport coefficients are computed by Monte-Carlo simulation over a wide range of mean free paths in the approximation of small-gyroradius, mono-energetic-particle distribution, and vanishing electric field for several stellarator fields. Pfirsch-Schluter, plateau, and ripple transport coefficients are obtained. The transport coefficients
Dommaschk, W., Lotz, W., Nuehrenberg, J.
openaire   +2 more sources

Nonlinear neoclassical transport in toroidal edge plasmas

Physics of Plasmas, 2001
In conventional neoclassical theory, the density and temperature gradients are not allowed to be as steep as frequently observed in the tokamak edge. In this paper the theory of neoclassical transport in a collisional, impure plasma is extended to allow for steeper profiles than normally assumed.
T. Fülöp, P. Helander
openaire   +1 more source

Neoclassical transport in the presence of fluctuations

Nuclear Fusion, 1992
The usual argument for automatic ambipolarity of neoclassical particle fluxes in a tokamak is based on the averaged toroidal momentum equation. It does not apply when fluctuations are present, because they also contribute to the momentum. The finite Larmor radius pressure tensor produced by electrostatic fluctuations makes a small contribution to the ...
openaire   +1 more source

Neoclassical transport in the presence of radiofrequency fields

Nuclear Fusion, 1989
The neoclassical fluxes induced by a radiofrequency field are calculated using the gyrokinetic equations. In general, the fluxes consist of a convective part and a diffusive part. The convective part is non-vanishing when the heating is asymmetric with respect to the magnetic field.
S.C. Chiu, V.S. Chan
openaire   +1 more source

Non-ambipolar neoclassical transport

Nuclear Fusion, 1995
The usual demonstration that neoclassical transport is automatically ambipolar, and independent of the radial electric field (Er), is shown to be valid only in an equilibrium axisymmetric plasma in which there is no other source or damping of toroidal momentum.
openaire   +1 more source

Neoclassical Transportation in the ELMO Bumpy Torus

Physical Review Letters, 1978
In the ELMO bumpy torus, neoclassical transport coefficients depend critically on the ambipolar electric field. These coefficients, calculated for arbitrary radial electric fields, are applied in a one-dimensional radial-transport calculation which, for the first time, treats the electric field self-consistently.
E. F. Jaeger, D. A. Spong, C. L. Hedrick
openaire   +1 more source