Plasma Position Constrained Free-Boundary MHD Equilibrium in Tokamaks using pyIPREQ

TL;DR

pyIPREQ is a new MHD equilibrium code for Tokamaks that incorporates plasma position constraints, vertical stability considerations, and supports limiter boundary specifications, enhancing modeling accuracy and diagnostic integration.

Contribution

The paper introduces pyIPREQ, a novel free-boundary MHD equilibrium code that supports prescribed magnetic axis positions and addresses vertical instabilities, extending previous frameworks like PEST and IPREQ.

Findings

Successfully benchmarked against existing codes and results.

Demonstrated applications on ADITYA-U and SST-1 Tokamaks.

Enabled equilibrium predictions using diagnostic magnetic axis data.

Abstract

A free-boundary, axisymmetric magnetohydrodynamic (MHD) equilibrium code, pyIPREQ, has been developed for Tokamak plasmas using finite difference and Green's function approach. The code builds upon the foundational frameworks of the PEST and IPREQ codes, introducing several enhancements and new capabilities. Notably, pyIPREQ supports the specification of limiter boundaries and enables the computation of key physical quantities. The code has also been extended to compute equilibria constrained by a prescribed magnetic axis position, which is particularly useful when such information can be inferred from the diagnostics data. In addition, pyIPREQ includes functionality to address vertical instabilities, a requirement for accurately modeling elongated plasma configurations. Benchmarking has been carried out against published results and the original IPREQ code. Applications are demonstrated for ADITYA-U Tokamak experiments, where magnetic axis measurements are available, and predictions are also made for SST-1 and ADITYA-U Tokamaks under various operational scenarios.