ON THE MOTION OF CHARGED PARTICLES IN NON-STANDARD TOKAMAK MAGNETIC FIELD

In this paper we analyze the motion of charged particles in a non-standard magnetic field that is of a Clebsch type representation where a magnetic perturbation is considered. The safety factor of ASDEX-Upgrade is used. Some aspects of the solutions of the guiding center system of equations are featured

A Double-Blind, Placebo-Controlled Pilot Study to Evaluate the Effect of Calcium Fructoborate on Systemic Inflammation and Dyslipidemia Markers for Middle-Aged People with Primary Osteoarthritis

The objective of this pilot study was to determine whether 15 days of dietary supplementation with calcium fructoborate could acutely modulate inflammatory and lipid blood markers in individuals diagnosed with primary osteoarthritis. During 2 weeks, a placebo-controlled, randomized, double-blind study was conducted on 116 subjects that were initially recruited. Seventy-two subjects started the study, being divided into four groups, and only 60 completed the study as designed. The aim was to compare the effects of calcium fructoborate to placebo on subjects diagnosed with knee primary osteoarthritis. The obtained outcomes were inflammation biomarkers (C-reactive protein, fibrinogen, and erythrocyte sedimentation rate) and lipid markers (triglycerides, total cholesterol, LDL cholesterol, and HDL cholesterol). No serious adverse events were reported. The calcium fructoborate showed beneficial effect on the inflammatory markers for all groups subjected to the treatment when compared with the placebo group and slight changes in the lipid metabolism. This study suggests that short-term (2 weeks) calcium fructoborate supplementation in patients with osteoarthritis symptoms has a favorable prognosis on inflammation diseases

Influence of magnetic shear ans stochastic electrostatic

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On revisited models of L-H transition for tokamak plasmas

Models corresponding to L/H transition in tokamak plasmas are revisited. Values for the thickness of the meso-phase and for the range of the control parameter in the bifurcation region are obtained. We shown that in the collisional case the double hysteresis is absent when the control parameter is positive and there are critical values of the effective frequency and electron diffusivity for the existence of a simple bifurcation. The influence of the impurity flux on the radial electric field bifurcation and the time behaviour of the later on the basis of a tangent hyperbolic time-dependent ion temperature were also studied.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

ExB diffusion in a 2-Dimensional electrostatic potential and sheared magnetic field: Direct particle simulations

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Electron diffusion in a sheared unperturbed magnetic field and an electrostatic stochastic field

The electron diffusion induced by a two-dimensional electrostatic turbulence, in a sheared slab approximation of the toroidal magnetic geometry, is studied firstly using the decorrelation trajectory method (DCT), secondly by direct numerical simulation. The former semi-analytical method allows us to go beyond the Corrsin approximation, thus allowing for a non-classical analysis of the particle trapping phenomenon. The DCT results are compared to the transport properties of the electrons obtained by numerical simulations assuming an isotropic spectrum of electrostatic drift type turbulence that is Gaussian for small wavevectors and power-law k-3 for large wavevectors. The 'radial' and the 'poloidal' running and asymptotic diffusion coefficients of thermal electrons are obtained for physically relevant parameter values. The existence of enhanced diffusion in the poloidal direction is observed in the presence of magnetic shear. The agreement between the semi-analytical method and the purely numerical method is pointed out. © 2006 The Royal Swedish Academy of Sciences.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Influence of magnetic shear and stochastic electrostatic field on the electron diffusion

The electron diffusion induced by a two-dimensional electrostatic turbulence, in a sheared slab approximation of the toroidal magnetic geometry, is studied by direct numerical simulation. The transport properties of the electrons are obtained by numerical simulations assuming an isotropic spectrum of electrostatic drift type turbulence that is Gaussian for small wave-vectors and power-law k-3 for large wave-vectors. The 'radial' and the 'poloidal' running and asymptotic diffusion coefficients of electrons are obtained for physically relevant parameter values and the existence of an enhanced diffusion in the poloidal direction is observed in the presence of magnetic shear.SCOPUS: cp.jinfo:eu-repo/semantics/publishe

Anisotropic electrostatic turbulence and zonal flow generation

In this paper we analyse the running and asymptotic diffusion coefficients of a plasma in the case of zonal flow generation by an anisotropic stochastic electrostatic potential. Both the weak and relatively strong turbulence regimes were analysed. The analysis of the diffusion coefficients in wave vector space provides an illustration of the fragmentation of drift wave structures in the radial direction and the generation of long-wavelength structures in the poloidal direction that are identified as zonal flows. We have shown that the fragmentation of drift wave structures is strongly influenced by the anisotropy parameter, the electrostatic Kubo number and by the initial values of the wave vector. © 2005 IOP Publishing Ltd.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Role of stochastic anisotropy and shear on magnetic field lines diffusion

Anisotropy in the magnetic fluctuation spectrum (stochastic anisotropy) and magnetic shear induce variations of global averaged quantities such as the running and the asymptotic diffusion tensors that can be investigated using a semi-analytical method. The study considers ranges for the anisotropy parameter, magnetic Kubo number and shear parameter leading to contrasting dynamical behaviors. In particular, the trapping of the stochastic magnetic field lines is analyzed. An asymptotic 'poloidal' velocity larger for stronger anisotropy is obtained for the wandering of the magnetic field lines for different values of the parameters. © 2007 IOP Publishing Ltd.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Characterization of zonal flow generation in weak electrostatic turbulence

The influence of the diamagnetic Kubo number, which is proportional to the diamagnetic drift velocity, on the zonal flow generation by an anisotropic stochastic electrostatic potential is considered from a semi-analytic point of view. The analysis is performed in the weak turbulence limit and as an analytical tool the decorrelation trajectory method is used. It is shown that the fragmentation of the drift wave structures (a signature of the zonal flow generation) is influenced not only by the anisotropy parameter and the electrostatic Kubo number as expected, but also by the diamagnetic Kubo number. Global Lagrangian averages of characteristic quantities are calculated and interpreted. © 2008 The Royal Swedish Academy of Sciences.SCOPUS: ar.jinfo:eu-repo/semantics/publishe