VEQ: A Fast Parametric Solver for Tokamak Equilibrium Modeling
Researchers have developed VEQPy, a compact parametric framework called Veloce EQuilibrium (VEQ) that rapidly solves fixed-boundary tokamak equilibria using a Grad-Shafranov solver with flexible source profiles. The tool accepts six different input routes for plasma parameters and achieves solve times ranging from 1.6 to 19 milliseconds depending on configuration complexity. This advance enables repeated low-latency equilibrium queries useful for tokamak modeling workflows, though pointwise diagnostics are needed to identify cases requiring higher-fidelity solutions.
VEQPy implements an axisymmetric fixed-boundary Grad-Shafranov solver designed for efficient tokamak equilibrium calculations in repeated-query scenarios. The framework uses MXH-type flux-surface harmonics and shifted-Chebyshev coefficients to represent radial profiles and source closures, accepting six different input routes that specify pressure-gradient, toroidal-field-function, poloidal-flux-gradient, enclosed toroidal current, current-density, and safety-factor information. Testing across three representative cases—a D-shaped tokamak, an H-mode plasma, and an X-point diverted configuration—demonstrated shape errors of 1.4e-3 to 1.9e-3 (normalized to minor radius) with solve times of 1.6 to 19 milliseconds. Diagnostic analysis revealed that the solver primarily improves interior force balance with enriched representations, while near-boundary contributions remain the dominant error source. The authors recommend retaining pointwise diagnostics to identify cases needing boundary refinement or higher-fidelity solves, positioning VEQ as a practical tool for rapid equilibrium-geometry queries in tokamak design and analysis workflows.
What's missing
The study does not discuss computational memory requirements, scalability to three-dimensional equilibria, or comparison with other existing fast equilibrium solvers in the literature. Additionally, the paper does not address applicability to alternative fusion concepts beyond tokamaks or validation against experimental tokamak data.
What different sources said
- arXiv physicsCenter
VEQ: a fast parametric Grad--Shafranov solver for fixed-boundary tokamak equilibria with flexible source profiles
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