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arXiv · 2609.33500

A Rapid Integrated Tokamak Modelling Approach for Coupled Profile and Equilibrium Evolution

Ruohan Zhang·Huasheng Xie·Feng Wang·Zheng-Xiong Wang
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Abstract

During plasma heating and current ramps the thermal and magnetic states of a tokamak evolve on different timescales. We present a rapid integrated tokamak modelling approach, which couples a variational fixed-boundary Grad--Shafranov equilibrium to sparse particle and energy flux matching and to weak-form current diffusion. An ITER-like pure-deuterium scenario is examined: a current ramp from 10 to 15~MA over 20~s, a 20~s flat-top and a 20~s ramp-down to 14~MA, under 80~MW of electron-cyclotron heating applied at the start. The toroidal current density at the pedestal top more than doubles during the ramp-up and then decreases during the flat-top as current redistributes inward. Thermal stored energy rises from 185.52 to 252.70~MJ and approaches its final value within the first few seconds. An independent calculation with the Fusion Synthesis Engine (FUSE) gives a stored-energy difference of 0.02\% at 60~s, whereas the largest profile differences occur in the core current density. Halving the coupling interval changes stored energy by at most 0.006\% at the selected radial resolution. The 60~s pulse, advanced through 600 coupling intervals of 0.1~s, takes 8.62~s on an Apple M4 Pro, which is at least two orders of magnitude faster than conventional integrated tokamak modelling solvers.

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Ruohan Zhang, Huasheng Xie, Feng Wang, Zheng-Xiong Wang. 2026-09-27. A Rapid Integrated Tokamak Modelling Approach for Coupled Profile and Equilibrium Evolution. https://arxiv.org/abs/2609.33500

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