Kinetic Turbulence in Astrophysical Plasmas: Waves and/or Structures?
Chen, Christopher H.K.
KAUST DepartmentFluid and Plasma Simulation Group (FPS)
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Permanent link to this recordhttp://hdl.handle.net/10754/632544
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AbstractThe question of the relative importance of coherent structures and waves has for a long time attracted a great deal of interest in astrophysical plasma turbulence research, with a more recent focus on kinetic scale dynamics. Here we utilize high-resolution observational and simulation data to investigate the nature of waves and structures emerging in a weakly collisional, turbulent kinetic plasma. Observational results are based on in situ solar wind measurements from the Cluster and Magnetospheric Multiscale (MMS) spacecraft, and the simulation results are obtained from an externally driven, three-dimensional fully kinetic simulation. Using a set of novel diagnostic measures, we show that both the large-amplitude structures and the lower-amplitude background fluctuations preserve linear features of kinetic Alfv´en waves to order unity. This quantitative evidence suggests that the kinetic turbulence cannot be described as a mixture of mutually exclusive waves and structures but may instead be pictured as an ensemble of localized, anisotropic wave packets or “eddies” of varying amplitudes, which preserve certain linear wave properties during their nonlinear evolution.
CitationGrošelj, D., Chen, C. H. K., Mallet, A., Samtaney, R., Schneider, K., & Jenko, F. (2019). Kinetic Turbulence in Astrophysical Plasmas: Waves and/or Structures? Physical Review X, 9(3). doi:10.1103/physrevx.9.031037
SponsorsWe gratefully acknowledge helpful conversations with D. Told, A. BaÃ±n Navarro, J. M. TenBarge, S. S. Cerri, B. D. G. Chandran, and A. A. Schekochihin. D. G. thanks in particular N. F. Loureiro for the fruitful exchange of ideas related to this work and for his assistance with obtaining the computing resources, and F. Tsung, V. Decyk, and W. Mori for discussions on particle-in-cell methods and simulations with the osiris code. C. H. K. C. was supported by a Science and Technology Facilities Council (STFC) Ernest Rutherford Fellowship No. ST/N003748/2, and A. M. by National Science Foundation (NSF) Grant No. AGS-1624501. K. S. acknowledges support by the French Research Federation for Fusion Studies carried out within the framework of the European Fusion Development Agreement (EFDA). The Cray XC40, Shaheen, at the King Abdullah University of Science and Technology (KAUST) in Thuwal, Saudi Arabia, was utilized for all the simulations reported. The authors would like to acknowledge the OSIRIS Consortium, consisting of UCLA and IST (Lisbon, Portugal) for the use of osiris 3.0 and for providing access to the osiris 3.0 framework.
PublisherAmerican Physical Society (APS)
JournalPhysical Review X