Collaborative Research: Multi-scale Dynamics of Kinetic Turbulence in Weakly Collisional, High-Beta Plasmas
The transport of energy and momentum and the heating of plasma particles by waves and turbulence are key ingredients in many problems at the frontiers of heliospheric and astrophysics research. This includes the heating and acceleration of the solar wind; the observational appearance of black-hole accretion flows on event-horizon scales; and the properties of the hot, diffuse plasmas that fill dark-matter halos. This work addressed the physics of plasma waves and turbulence in weakly collisional, weakly magnetized (high-beta) plasmas. In this regime, deviations from local thermodynamic equilibrium (i.e., pressure anisotropies) and the instabilities they excite can dramatically change the properties of waves and turbulence from those predicted by fluid (i.e., magnetohydrodynamic) and linear kinetic theories. Through a combination of analytic theory and first-principles kinetic simulations, we have shown that: (1) ion-acoustic waves of sufficient amplitude drive pressure anisotropies large enough to trigger kinetic Larmor-scale instabilities, which in turn interrupt the otherwise strong collisionless damping such waves suffer; (2) pressure anisotropies generated by fluctuating magnetic fields in strong Alfvénic turbulence produce a viscous scale comparable to the driving scale and a cascade with significant non-local interactions; (3) strong Alfvénic turbulence in an expanding high-beta plasma self-organizes to maintain critical balance, even as kinetic Larmor-scale instabilities regulate the plasma viscosity and reduce the elasticity of magnetic-field lines; (4) imbalanced Alfvénic turbulence leads to a "helicity barrier" that ultimately triggers the cyclotron heating of ions, in a manner consistent with spacecraft measurements taken in the solar wind; and (5) relativistic synchrotron-radiating plasmas develop kinetically unstable pressure anisotropy, which changes the nature of their cooling in a way that can couple the thermodynamics of ions and electrons.
- Research Organization:
- Princeton Univ., NJ (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- DOE Contract Number:
- SC0019047; SC0019046
- OSTI ID:
- 1909989
- Report Number(s):
- DE-SC0019047; TRN: US2313661
- Resource Relation:
- Related Information: M. W. Kunz, J. Squire, A. A. Schekochihin, E. Quataert, "Self-sustaining sound in collisionless, high-beta plasma", Journal of Plasma Physics 86, 905860603 (2020). DOI: 10.1017/S0022377820001312A. F. A. Bott, L. Arzamasskiy, M. W. Kunz, E. Quataert, J. Squire, "Adaptive critical balance and firehose instability in an expanding, turbulent, collisionless plasma", The Astrophysical Journal Letters 922, L35 (2021). DOI: 10.3847/2041-8213/ac37c2J. Squire, R. Meyrand, M. W. Kunz, L. Arzamasskiy, A. A. Schekochihin, E. Quataert, "High-frequency heating of the solar wind triggered by low-frequency turbulence", Nature Astronomy 6, 715 (2022). DOI: 10.1038/s41550-022-01624-zV. Zhdankin, M. W. Kunz, D. A. Uzdensky, "Synchrotron firehose instability", The Astrophysical Journal, in press (2023). arXiv:2210.16891L. Arzamasskiy, M. W. Kunz, J. Squire, E. Quataert, "Kinetic turbulence in collisionless high-beta plasmas", Physical Review X, in press (2023). arXiv:2207.05189S. Majeski, M. W. Kunz, J. Squire, "Microphysically modified magnetosonic modes in collisionless, high-beta plasmas", submitted to Journal of Plasma Physics (2023).A. F. A. Bott, M. W. Kunz, E. Quataert, L. Arzamasskiy, J. Squire, "Thermodynamics and collisionality in firehose-susceptible high-beta plasmas", in preparation (2023).
- Country of Publication:
- United States
- Language:
- English
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