Description
Ion cyclotron resonance frequency (ICRF) heating is an important auxiliary-heating method for stellarators, but full-wave modeling is challenging because the magnetic equilibrium, plasma boundary, antenna and surrounding conducting structures are intrinsically three-dimensional. We present an experiment-informed workflow for ICRF modeling in Wendelstein 7-X (W7-X) using the Petra-M finite-element framework.
The W7-X antenna and vacuum-vessel geometry are incorporated in a tetrahedral computational model containing vacuum, cold-plasma core and lower-density edge regions. Magnetic-field components are reconstructed from VMEC equilibria, rescaled to the experimental field and interpolated onto a regular three-dimensional grid. Core electron-density profiles are fitted to Thomson-scattering measurements and mapped to flux surfaces. An ICRH-side reflectometer fit supplies the edge profile, while an Alkali-beam fit represents the magnetic-island contribution. Experimental RF boundary conditions are estimated by comparing active-reflection-coefficient measurements with a Petra-M four-port S-matrix terminated by trial matching capacitances.
The workflow is applied to two discharges: H–(³He) minority heating with dipole phasing, and an H–(³He)–⁴He three-ion scenario with single strap monopole phasing.
Preliminary full-wave solutions show three-dimensional RF electric-field structure in the antenna and plasma region for both cases. Quantitative antenna-loading comparisons, convergence studies, absorption calculations and experimental validation remain to be completed. The present work establishes the integrated W7-X modeling workflow and identifies the numerical and experimental checks required before drawing conclusions about heating efficiency or power deposition.