Influence of rotation on axisymmetric plasma equilibria: double-null DTT scenario

TL;DR

This paper analytically explores how toroidal plasma rotation affects equilibrium properties in tokamaks, focusing on double-null scenarios relevant for the DTT experiment, revealing rotation-induced variations in plasma parameters.

Contribution

It introduces analytical solutions to the rotating Grad-Shafranov equation using polynomial and Bessel function representations, enabling detailed modeling of plasma equilibria with rotation.

Findings

Rotation enhances poloidal beta in plasma equilibria.

Double-null configurations are compatible with various plasma velocities.

Analytical models accurately reproduce DTT-like plasma boundaries.

Abstract

We study the dependence of some relevant tokamak equilibrium quantities on the toroidal plasma rotation. The Grad-Shafranov equation generalised to the rotating case is analytically solved employing two different representations for the homogenous solution. Using an expression in terms of polynomials, we describe the separatrix shape by a few geometrical parameters, reproducing different plasma scenarios such as double-null and inverse triangularity. In this setting, the introduction of toroidal rotation corresponds to variations on relevant plasma quantities, most notably an enhancement of the poloidal beta. Using a more general expression in terms of Bessel functions, we reconstruct the full plasma boundary of the double-null configuration proposed for the upcoming DTT experiment, demonstrating how said configuration is compatible with different values of the plasma velocity.