Contribution of reversed shear in reducing the anomalous transport

Abstract

In this paper we have studied the contribution of reversed shear in reducing the anomalous transport in tokamak using the analytical and simulations approaches We have used a special model for the drift wave fields. Comparison between particles trajectories for normal and negative shear is carried out. The diffusion coefficient of particles for the two cases normal and reversed shear is evaluated.

Transport barriers with magnetic shear in a tokamak

“…We have used the ITER Tokamak parameters [14], and we simulate the parameters below. We observe that the trajectories have the same shape as we obtained before in our results for the TEXT tokamak [1,[3][4][5][6][7][8][9][10] but for the highest values of the potential, because for the smaller values, we could not observe any difference between the two profiles of the safety factor.…”

“…In order to introduce the effects of reversed magnetic shear and the radial electric field, we define the system of equations of the global mapping as follows [1][2][3][4][5][6][7][8][9][10][11][12].…”

“…To evaluate the plasma particle diffusion [1,[3][4][5][6][7][8][9][10] through the magnetic surfaces within the tokamak reactors, we simulated the particulate diffusion coefficients in two cases. We used the classic formula…”

“…In this paper, we reproduce the entire mapping results [1][2][3][4][5][6][7][8][9][10] using the ITER parameters and we study the influence of the perturbation modes on the diffusion coefficient. We make a comparison between the results obtained using ITER and TEXT parameters.…”

Influence of the electric and magnetic shears on tokamak transport

“…Moreover, symplectic drift wave maps in the vicinity of given radial position and safety factor have been derived from these models [15,18] to numerically investigate the transport dependence on shear spatial profiles. Thus, for these maps, the transport reduction, caused by the combined effects of radial electric field shear and both monotonic and reversed shear magnetic q profiles, has been investigated [16,19,20]. However, applications of the proposed models to investigate global transport in tokamaks and the escape of particles to the walls still remain to be explored by numerical integration of the equations of motion.…”