Implications of a two-fluid heat diffusion model for RF condensation effects in magnetic islands

TY - JOUR

T1 - Implications of a two-fluid heat diffusion model for RF condensation effects in magnetic islands

AU - Hartigan-O'Connor, E. J.

AU - Nies, R.

AU - Reiman, A. H.

N1 - Publisher Copyright: © 2026 Author(s).

PY - 2026/5/1

Y1 - 2026/5/1

N2 - Theoretical calculations have predicted an “RF condensation” effect through which the temperature perturbation and current drive may be nonlinearly enhanced in electron cyclotron (EC) heated magnetic islands. Previously, two-fluid effects had been neglected in the OCCAMI code used to model RF condensation. For realistic experimental conditions, we show that two-fluid effects in an EC heated plasma may have a major impact on RF condensation. Less collisional plasmas, where electron and ion temperatures are decoupled, exhibit an enhanced linear temperature perturbation in the island, and an even stronger nonlinear enhancement of the perturbed temperature. This can occur even when nonlinear effects are small in the single-fluid limit. We also calculate corresponding hysteresis effects. Finally, we demonstrate that other physical effects, including the rotation of the magnetic island and the Gaussian spread of the beam from a gyrotron, can significantly decrease the predicted observable RF condensation effect.

AB - Theoretical calculations have predicted an “RF condensation” effect through which the temperature perturbation and current drive may be nonlinearly enhanced in electron cyclotron (EC) heated magnetic islands. Previously, two-fluid effects had been neglected in the OCCAMI code used to model RF condensation. For realistic experimental conditions, we show that two-fluid effects in an EC heated plasma may have a major impact on RF condensation. Less collisional plasmas, where electron and ion temperatures are decoupled, exhibit an enhanced linear temperature perturbation in the island, and an even stronger nonlinear enhancement of the perturbed temperature. This can occur even when nonlinear effects are small in the single-fluid limit. We also calculate corresponding hysteresis effects. Finally, we demonstrate that other physical effects, including the rotation of the magnetic island and the Gaussian spread of the beam from a gyrotron, can significantly decrease the predicted observable RF condensation effect.

UR - https://www.scopus.com/pages/publications/105038925298

UR - https://www.scopus.com/pages/publications/105038925298#tab=citedBy

U2 - 10.1063/5.0323269

DO - 10.1063/5.0323269

M3 - Article

SN - 1070-664X

VL - 33

JO - Physics of Plasmas

JF - Physics of Plasmas

IS - 5

M1 - 052507

ER -