Professor Felix Parra Diaz: Publications

Validating and optimizing mismatch tolerance of Doppler backscattering measurements with the beam model (invited)

Review of Scientific Instruments AIP Publishing 93:10 (2022) 103536

Authors:

VH Hall-Chen, J Damba, FI Parra, QT Pratt, CA Michael, S Peng, TL Rhodes, NA Crocker, JC Hillesheim, R Hong, S Ni, WA Peebles, CE Png, J Ruiz Ruiz

Finite orbit width effects in large aspect ratio stellarators

Journal of Plasma Physics Cambridge University Press (CUP) 88:5 (2022) 905880507

Authors:

Vincent d'Herbemont, Felix I Parra, Iván Calvo, José Luis Velasco

Beam model of Doppler backscattering

Plasma Physics and Controlled Fusion IOP Publishing 64:9 (2022) 095002

Authors:

Valerian H Hall-Chen, Felix I Parra, Jon C Hillesheim

The power threshold of H-mode access in mixed hydrogen–tritium and pure tritium plasmas at JET with ITER-like wall

Nuclear Fusion IOP Publishing 62:8 (2022) 086005

Authors:

G Birkenmeier, ER Solano, E Lerche, D Taylor, D Gallart, MJ Mantsinen, E Delabie, IS Carvalho, P Carvalho, E Pawelec, JC Hillesheim, F Parra Diaz, C Silva, S Aleiferis, J Bernardo, A Boboc, D Douai, E Litherland-Smith, R Henriques, KK Kirov, CF Maggi, J Mailloux, M Maslov, FG Rimini, SA Silburn, P Sirén, H Weisen, JET Contributors

Gyrokinetic electrostatic turbulence close to marginality in the Wendelstein 7-X stellarator

Physical Review E American Physical Society 106 (2022) L013202

Authors:

Alessandro Zocco, Linda Podavini, José Manuel Garcìa-Regaña, Michael Barnes, Felix I Parra, A Mishchenko, Per Helander

Abstract:

The transition from strong (fluidlike) to nearly marginal (Floquet-type) regimes of ion-temperature-gradient (ITG) driven turbulence is studied in the stellarator Wendelstein 7-X by means of numerical simulations. Close to marginality, extended (along magnetic field lines) linearly unstable modes are dominant, even in the presence of kinetic electrons, and provide a drive that results in finite turbulent transport. A total suppression of turbulence above the linear stability threshold of the ITG modes, commonly present in tokamaks and known as the “Dimits shift,” is not observed. We show that this is mostly due to the peculiar radial structure of marginal turbulence, which is more localized than in the fluid case and therefore less likely to be stabilized by shearing flows.

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