학술논문

Tokamak equilibria with incompressible flow parallel to the magnetic field and pressure anisotropy.
Document Type
Article
Source
AIP Advances. Jun2021, Vol. 11 Issue 6, p1-11. 11p.
Subject
*PLASMA flow
*MAGNETIC fields
*MACH number
*ANISOTROPY
*EQUILIBRIUM
*INCOMPRESSIBLE flow
Language
ISSN
2158-3226
Abstract
It is believed that plasma rotation can affect transitions to the advanced confinement regimes in tokamaks. In addition, in order to achieve fusion temperatures, modern tokamaks rely on auxiliary heating methods. These methods generate pressure anisotropy in the plasma. For incompressible rotation with pressure anisotropy, the equilibrium is governed by a generalized Grad–Shafranov (GGS) equation and a decoupled Bernoulli-type equation for the effective pressure, p ̄ = ( p ∥ + p ⊥ ) / 2 , where p∥ (p⊥) is the pressure tensor element parallel (perpendicular) to the magnetic field. In the case of plasma rotation parallel to the magnetic field, the GGS equation can be transformed to one equation identical in form with the GS equation. In this study, by making use of the aforementioned property of the GGS equation for parallel plasma rotation, we have constructed ITER-like numerical equilibria by extending HELENA, an equilibrium fixed-boundary solver, and examined the impact of rotation and anisotropy on certain equilibrium quantities. The main conclusions are that the addition of pressure anisotropy to rotation allows the profile shaping of the equilibrium quantities to much more extent compared to the isotropic case, thus favoring the confinement, and allows extension of the parametric space of the Mach number corresponding to higher values. Furthermore, the impact of pressure anisotropy on the equilibrium quantities is stronger than that of the rotation for most of the quantities examined in view of respective experimental values. For the pressure components, the impact of the pressure anisotropy is the same, regardless of whether the power is deposited parallel or perpendicular to the magnetic surfaces, thus implying that there is no preferable heating direction, while for the current density, the heating parallel to the magnetic surfaces seems to be beneficial for the current gradient-driven instabilities. [ABSTRACT FROM AUTHOR]