Abstract Details
Abstracts
Author: François Waelbroeck
Requested Type: Poster
Submitted: 2026-03-20 13:42:53
Co-authors: M. S. Cancino and J. J. Martinell
Contact Info:
Univ. Texas at Austin
Speedway and Dean Keaton
Austin, TX 78712
USA
Abstract Text:
Thin magnetic islands are of interest in several contexts including Micro Tearing Modes (MTM), seed islands for Neoclassical Tearing Modes (NTM), edge stabilization by shielded Resonant Magnetic Perturbations (RMP), and Error Field Correction (EFC). In an inhomogeneous plasma, islands excite drift-acoustic waves that propagate away from the separatrix like a wake. [1,2] For thin islands (w<rs) and weak shear, the wake carries away momentum that it redeposits at an absorption point where om=k//cs. Here rs is the ion-sound Larmor radius, om is the island frequency in the plasma frame, k// is the parallel wavevector and cs is the sound speed. The balance between radiative and viscous drags determines the relative velocity of the island with respect to the plasma and thereby (i) the magnitude and sign of the polarization current and (ii) the extent of profile flattening and the resulting modification to the bootstrap current. These two effects play a dominant role in determining the island size. This poster will present an analytic model for the radiation drag and discuss its implications.
[1] Hypersonic drift-tearing magnetic islands in tokamak plasmas, R. Fitzpatrick and F. L. Waelbroeck, Phys. Plasmas 14, 122502 (2007). https://dx.doi.org/10.1063/1.2811928
[2] Drag exerted by drift-acoustic radiation on a magnetic island, M. S. Cancino-Escobar, J. J. Martinell, and F. L. Waelbroeck, Phys. Plasmas 31, 072501 (2024) https://doi.org/10.1063/5.0200902
Characterization: 4.0
Comments: