Radial transport of toroidal angular momentum in tokamaks

TL;DR

This paper derives comprehensive second-order gyrokinetic equations to accurately compute the radial flux of toroidal angular momentum in tokamaks, crucial for understanding intrinsic rotation profiles.

Contribution

It presents the first complete set of second-order equations for turbulent distribution functions and electrostatic potential in tokamaks without simplifying assumptions about magnetic field ratios.

Findings

Provides explicit $O(psilon^2)$ equations for turbulence components.

Enables precise calculation of angular momentum transport.

Applicable to any tokamak configuration.

Abstract

The radial flux of toroidal angular momentum is needed to determine tokamak intrinsic rotation profiles. Its computation requires knowledge of the gyrokinetic distribution functions and turbulent electrostatic potential to second-order in $\epsilon = \rho/L$, where $\rho$ is the ion Larmor radius and $L$ is the variation length of the magnetic field. In this article, a complete set of equations to calculate the radial transport of toroidal angular momentum in any tokamak is presented. In particular, the $O(\epsilon^2)$ equations for the turbulent components of the distribution functions and electrostatic potential are given for the first time without assuming that the poloidal magnetic field over the magnetic field strength is small.