Collision Simulation in plasma Sheath Using the Monte Carlo Technic

In this work we studied the collisions in the sheath and their influence on the energy transferred to the cathode by Monte carlo simulation .The comparison between results obtained by Monte Carlo simulation and those obtained by simulation of Runge Kutta is carried out. We stadied too the influence of the collision on the erosion of the cathode, and we give a technique to calculate the energy of vaporisation.In this work we studied the collisions in the sheath and their influence on the energy transferred to the cathode by Monte carlo simulation .The comparison between results obtained by Monte Carlo simulation and those obtained by simulation of Runge Kutta is carried out. We stadied too the influence of the collision on the erosion of the cathode, and we give a technique to calculate the energy of vaporisation

Contribution of particles and magnetic field lines diffusion toAnomalous transport in tokamak

Research into anomalous transport is aimed at two different sources: turbulent fluctuations in either the electric or the magnetic field. In each case a model has been developed describing the influence of fluctuating field on particles transport. The dynamic of particles guiding centers in a configuration of electric and magnetic turbulence is studied in four dimensional equations of motion. An Hamiltonian description shows that the particles trajectories are described by action angle variables system. It has been demonstrated that the island topology appears at positions near resonant surface if there are the small perturbations. Localized chaotic regions appear while increasing the perturbation and spread up to a fully stochastic situation. The standard definition coefficient D uses the limit of the mean square excursion; an expression of D useful to describe transport in a finite region can be obtained from the exit times τ i of particles. In the present paper, we compute the numerical diffusion coefficient in the case of electric and magnetic turbulence, the comparison with quasi-linear theory is made for the two cases. This study indicates that electric fluctuations might be the dominant source of anomalous transport for the particles at low parallel velocity, whereas magnetic fluctuations effact particles transport at great parallel velocity. The D/D ql ratio converges to one for the case where numerical diffusion coefficient coincides well with the quasi-linear diffusion coefficient.Research into anomalous transport is aimed at two different sources: turbulent fluctuations in either the electric or the magnetic field. In each case a model has been developed describing the influence of fluctuating field on particles transport. The dynamic of particles guiding centers in a configuration of electric and magnetic turbulence is studied in four dimensional equations of motion. An Hamiltonian description shows that the particles trajectories are described by action angle variables system. It has been demonstrated that the island topology appears at positions near resonant surface if there are the small perturbations. Localized chaotic regions appear while increasing the perturbation and spread up to a fully stochastic situation. The standard definition coefficient D uses the limit of the mean square excursion; an expression of D useful to describe transport in a finite region can be obtained from the exit times τ i of particles. In the present paper, we compute the numerical diffusion coefficient in the case of electric and magnetic turbulence, the comparison with quasi-linear theory is made for the two cases. This study indicates that electric fluctuations might be the dominant source of anomalous transport for the particles at low parallel velocity, whereas magnetic fluctuations effact particles transport at great parallel velocity. The D/D ql ratio converges to one for the case where numerical diffusion coefficient coincides well with the quasi-linear diffusion coefficient

THE INFLUENCES OF MAGNETIC SHEAR ON THE IMPROVEMENT OF THE QUALITY OF CONFINEMENT IN THE PLASMA OF TOKAMAK

In this paper we have studied the influence of reversed shear on the improvement of the confinement’s quality in the plasma of tokamak and especially in reducing the anomalous transport. For that, we have used a special model for the drift wave fields. Comparison between particles trajectories for normal and reversed shear is carried out in 2D and 3D presentation. Also, the diffusion coefficient of particles for the two cases, normal and negative shear, is evaluated.In this paper we have studied the influence of reversed shear on the improvement of the confinement’s quality in the plasma of tokamak and especially in reducing the anomalous transport. For that, we have used a special model for the drift wave fields. Comparison between particles trajectories for normal and reversed shear is carried out in 2D and 3D presentation. Also, the diffusion coefficient of particles for the two cases, normal and negative shear, is evaluated

Uporaba magnetskog smika za poboljšanje zadržavanja plazme u tokomaku

We investigate the influence of reversed shear on the improvement of the confinement\u27s quality in the plasma of a tokamak, specifically in reducing the anomalous transport. We use a special model for the drift wave fields. Comparison between the particle trajectories for normal and reversed shear is carried out in 2D and 3D presentation. The diffusion coefficient of particles and the radial electric field for the two cases, normal and negative shear, have been evaluated.Proučavamo utjecaj obrnutog smika za poboljšanje zadržavanja plazme u tokomaku, posebice za smanjenje anomalnog prijenosa. Primijenili smo poseban model za posmična valna polja. Usporedbu putanja čestica za normalan i obrnuti posmik načinili smo u 2D i 3D prostoru. Također smo odredili difuzijske koeficijente za čestice i radijalno električno polje za dva slučaja, normalan i obrnuti posmik

Diffusion of stochastic magnetic field lines in a confined plasma using the generalized mapping

The evolution of stochastic magnetic field lines has been studied numerically. Also, we have studied the transition from partial stochasticity to global stochasticity of magnetic field lines. We have developed the analytical calculations of diffusion coefficient of magnetic field lines through magnetic surfaces using the Fourier paths technique. The magnetic field lines are described by the generalized mapping. A comparison between our analytical and numerical calculations has been done.The evolution of stochastic magnetic field lines has been studied numerically. Also, we have studied the transition from partial stochasticity to global stochasticity of magnetic field lines. We have developed the analytical calculations of diffusion coefficient of magnetic field lines through magnetic surfaces using the Fourier paths technique. The magnetic field lines are described by the generalized mapping. A comparison between our analytical and numerical calculations has been done

Uporaba magnetskog smika za poboljšanje zadržavanja plazme u tokomaku

We investigate the influence of reversed shear on the improvement of the confinement\u27s quality in the plasma of a tokamak, specifically in reducing the anomalous transport. We use a special model for the drift wave fields. Comparison between the particle trajectories for normal and reversed shear is carried out in 2D and 3D presentation. The diffusion coefficient of particles and the radial electric field for the two cases, normal and negative shear, have been evaluated.Proučavamo utjecaj obrnutog smika za poboljšanje zadržavanja plazme u tokomaku, posebice za smanjenje anomalnog prijenosa. Primijenili smo poseban model za posmična valna polja. Usporedbu putanja čestica za normalan i obrnuti posmik načinili smo u 2D i 3D prostoru. Također smo odredili difuzijske koeficijente za čestice i radijalno električno polje za dva slučaja, normalan i obrnuti posmik

Modelling of Collision in the Plasma Sheath and the Cathode Erosion of Electrical Arc

In order to improve many industrial applications of the plasma sheath and the cathode erosion of electrical arc, the prime objective of this paper is to treat the modelling and simulation of the effects of ions collisionality on the plasma sheath and to determine the collisional dependence of the sheath width and the ion impact energy on the wall using the Runge-Kutta Routrine on the presence or the absence of the term source in the continuity equation . Then , to explain the dependence of the measured erosion rate of the cathode by considering the cathode spot heat balance equation coupled with equation obtained from the sheath and taking into account the physical phenomena such as ion and electron fluxes, radiation, thermal conductivity and evaporation.In order to improve many industrial applications of the plasma sheath and the cathode erosion of electrical arc, the prime objective of this paper is to treat the modelling and simulation of the effects of ions collisionality on the plasma sheath and to determine the collisional dependence of the sheath width and the ion impact energy on the wall using the Runge-Kutta Routrine on the presence or the absence of the term source in the continuity equation . Then , to explain the dependence of the measured erosion rate of the cathode by considering the cathode spot heat balance equation coupled with equation obtained from the sheath and taking into account the physical phenomena such as ion and electron fluxes, radiation, thermal conductivity and evaporation

The influence of magnetic reversed shear in the improvement of quality of confinement in the plasma of Tokamak: Comparison between TEXTOR & ITER

The reversed magnetic shear is the most important factor in the studies of the plasmas of tokamak. In this paper we focus our research, at first stage, on the control of the improved confinement regimes by studying the influence of reversed shear on its quality in the plasma of tokamak and especially in reducing the anomalous transport in TEXT and ITER, then we study the influence of perturbation’s modes in the particles diffusion. In the whole simulations, a comparison between results obtained using ITER and TEXT parameters is carried out.The reversed magnetic shear is the most important factor in the studies of the plasmas of tokamak. In this paper we focus our research, at first stage, on the control of the improved confinement regimes by studying the influence of reversed shear on its quality in the plasma of tokamak and especially in reducing the anomalous transport in TEXT and ITER, then we study the influence of perturbation’s modes in the particles diffusion. In the whole simulations, a comparison between results obtained using ITER and TEXT parameters is carried out

Modelling and simulation of dusty plasma sheath

The aim of this paper is to study the behaviour of sheath structure in dusty plasma with collisions, and simulation of the effects collisionality on the plasma sheath using the Runge-Kutta routine. Exact numerical solutions of the model are used to determine the collisional dependence of the sheath width and the ion impact energy at the wall.The aim of this paper is to study the behaviour of sheath structure in dusty plasma with collisions, and simulation of the effects collisionality on the plasma sheath using the Runge-Kutta routine. Exact numerical solutions of the model are used to determine the collisional dependence of the sheath width and the ion impact energy at the wall