Abstract Details
Abstracts
Author: Jacobo Varela Rodriguez
Requested Type: Consider for Invited
Submitted: 2026-03-01 19:10:34
Co-authors: J. Varela, J. Garcia, S. Mazzi, Y. Kazakov, Ž. Štancar, M. Baruzzo, J. Ongena, D. Spong, L. Garcia, Y. Ghai, B. Breizman, S.E. Sharapov, D. Zarzoso, M. Poradzinski, JET contributors and EUROfusion Tokamak Exploitation team
Contact Info:
IFS UT-Austin
2515 Speedway
Austin, TX 78712
Estados Unidos
Abstract Text:
Fuel dilution at the core of a fusion reactor linked to large concentrations of He ash is a major concern for its performance. Present study is dedicated to analyze He ash removal induced by fish-bones for a reactor like configuration, a JET D-T discharge. On that aim, nonlinear simulations are performed using the code FAR3d considering two different scenarios with respect to the fish-bone saturation: soft MHD limit (smooth and local saturation) and hard MHD limit (plasma collapse and bursting activity). Fish-bones are destabilized by trapped Hydrogen accelerated to MeV energies by the ion cyclotron resonance heating (IRCH). The simulations indicate Fish-bones saturation in the soft MHD limit may not be able to induce enough He ash outwards transport to avoid the fuel dilution, at least for the configuration analyzed. On the other hand, Fish-bones saturation in the hard MHD limit may be capable to reduce the fuel dilution in the core, but causing an accumulation at the middle plasma region because no net He ash net are observed. This is explain by the mode width, located between the magnetic axis and r/a = 0.25. Simulations in the hard MHD limit also show a partial plasma collapse at the inner plasma induced by the fish-bone overlapping with 2/2-3/3 overtones, leading to a ballistic transport of the trapped H and a quasi-ballistic for the He ash. After the collapse, secondary n=4 to 6 AE / EPM are destabilized in the inner-middle plasma region, causing the diffusive-like transport of trapped Hydrogen and He ash. The simulations also indicate the generation of intense shear flows that may constrain He ash flows, connected to a reduction of the turbulent transport. The analysis also shows a critical density gradient behavior with respect to the trapped Hydrogen EP density profile but not for the He ash, leading to a large enhancement of the trapped Hydrogen transport as the amplitude of the fish-bone increases although smaller for the He ash.
Characterization: 1.0
Comments: