Electromagnetic turbulence suppression by energetic particle driven modes. (17th September 2019)

• Record Type: Journal Article
• Authors: Di Siena, A.; Görler, T.; Poli, E.; Navarro, A. Bañón; Biancalani, A.; Jenko, F.
• Is Part Of: Nuclear fusion. Volume 59:Number 12(2019:Dec.)
• Publication Date: 2019-09-17
• Subjects: energetic particles -- plasma turbulence -- nonlinear mode coupling -- marginally stable modes; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ab4088
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: In recent years, a strong reduction of plasma turbulence in the presence of energetic particles has been reported in a number of magnetic confinement experiments and corresponding gyrokinetic simulations. While highly relevant to performance predictions for burning plasmas, an explanation for this primarily nonlinear effect has so far remained elusive. A thorough analysis finds that linearly marginally stable energetic particle driven modes are excited nonlinearly, depleting the energy content of the turbulence and acting as an additional catalyst for energy transfer to zonal modes (the dominant turbulence saturation channel). Respective signatures are found in a number of simulations for different JET and ASDEX Upgrade discharges with reduced transport levels attributed to energetic ion effects.