# Turbulent Contributions to Ohm's Law in Axisymmetric Magnetized Plasmas

## TL;DR

This paper investigates how magnetic turbulence influences current density in axisymmetric plasmas, revealing that turbulence can significantly contribute to plasma current and power generation, comparable to neoclassical effects.

## Contribution

It introduces a turbulent extension of Ohm's law incorporating anomalous resistivity and bootstrap-like effects, providing new insights into plasma current dynamics.

## Key findings

- Turbulence can generate 20-25% of the current compared to neoclassical bootstrap.
- Turbulent bootstrap effect and anomalous resistivity significantly impact power and current.
- Hyper-resistivity is crucial for maintaining current profiles in fully bootstrapped tokamaks.

## Abstract

The effect of magnetic turbulence in shaping the current density in axisymmetric magnetized plasma is analyzed using a turbulent extension of Ohm's law derived from the self-consistent action-angle transport theory. Besides the well-known hyper-resistive (helicity-conserving) contribution, the generalized Ohm's law contains an anomalous resistivity term, and a turbulent bootstrap-like term proportional to the current density derivative. The numerical solution of the equation for equilibrium and turbulence profiles characteristic of conventional and advanced scenarios shows that, trough "turbulent bootstrap" effect and anomalous resistivity turbulence can generate power and parallel current which are a sizable portion (about 20-25%) of the corresponding effects associated with the neoclassical bootstrap effect. The degree of alignment of the turbulence peak and the pressure gradient plays an important role in defining the steady-state regime. In fully bootstrapped tokamak, the hyper-resistivity is essential in overcoming the intrinsic limitation of the hollow current profile.