Journal article
The velocity-space signature of transit-time damping
Journal of plasma physics, Vol.90(4), 535900401
09/24/2024
DOI: 10.1017/S0022377824000667
Appears in UI Libraries Support Open Access
Abstract
Transit-time damping (TTD) is a process in which the magnetic mirror force – induced by the parallel gradient of magnetic field strength – interacts with resonant plasma particles in a time-varying magnetic field, leading to the collisionless damping of electromagnetic waves and the resulting energization of those particles through the perpendicular component of the electric field, $E_\perp$. In this study, we utilize the recently developed field–particle correlation technique to analyse gyrokinetic simulation data. This method enables the identification of the velocity-space structure of the TTD energy transfer rate between waves and particles during the damping of plasma turbulence. Our analysis reveals a unique bipolar pattern of energy transfer in the velocity-space characteristic of TTD. By identifying this pattern, we provide clear evidence of TTD's significant role in the damping of strong plasma turbulence. Additionally, we compare the TTD signature with that of Landau damping (LD). Although they both produce a bipolar pattern of phase-space energy density loss and gain about the parallel resonant velocity of the Alfvénic waves, they are mediated by different forces and exhibit different behaviours as the perpendicular velocity $v_\perp \to 0$. We also explore how the dominant damping mechanism varies with ion plasma beta $\beta _i$, showing that TTD dominates over LD for $\beta _i > 1$. This work deepens our understanding of the role of TTD in the damping of weakly collisional plasma turbulence and paves the way to seek the signature of TTD using in situ spacecraft observations of turbulence in space plasmas.
Details
- Title: Subtitle
- The velocity-space signature of transit-time damping
- Creators
- Rui Huang - 1Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USAGregory G. Howes - 1Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USAAndrew J. McCubbin - Johns Hopkins University
- Resource Type
- Journal article
- Publication Details
- Journal of plasma physics, Vol.90(4), 535900401
- DOI
- 10.1017/S0022377824000667
- ISSN
- 0022-3778
- eISSN
- 1469-7807
- Publisher
- Cambridge University Press
- Number of pages
- 39
- Grant note
- NASA: 80NSSC18K0643, 80NSSC18K1217, 80NSSC18K1371 NSF: AGS-1842561
Supported by NASA grants 80NSSC18K0643, 80NSSC18K1217 and 80NSSC18K1371 and NSF grant AGS-1842561.
- Comment
- Part of: Fundamental Problems of Plasma Astrophysics
- Language
- English
- Date published
- 09/24/2024
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984719236902771
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