Comment on Nuclear Fusion 66, 016012 (2026) and arXiv:2508.03561 by Richard Fitzpatrick, A Simple Model of Current Ramp-Up and Ramp-Down in Tokamaks

TL;DR

This paper critiques a recent Nuclear Fusion article, identifying fundamental errors in its physics model of magnetic flux evolution in tokamaks and clarifying misrepresentations of prior work.

Contribution

It provides a detailed correction of the flawed physics assumptions in Fitzpatrick's model and clarifies the accurate understanding of magnetic flux dynamics in tokamaks.

Findings

Identifies fundamental errors in Fitzpatrick's physics model.

Clarifies the correct physics of poloidal magnetic flux evolution.

Highlights misrepresentations of prior work in the criticized article.

Abstract

The article Nuclear Fusion \textbf{66}, 016012 (2026) by Richard Fitzpatrick is based on fundamental errors in the physics of the evolution of the poloidal magnetic flux in tokamaks. This paper was inspired by an article $\big<$arxiv.org/abs/2507.05456$\big>$ by Allen Boozer, which was posted on arXiv in various versions. The September 9, 2025 version was submitted to the Physics of Plasmas and flatly rejected until the issues raised in the Nuclear Fusion paper had been addressed. Not only did the Nuclear Fusion paper make a number of fundamental errors in science, it also misrepresented the views clearly stated in the arXiv article and even more explicitly in email exchanges that were repeatedly cited as ``private communication."