The Velocity-Space Signature of Transit-Time Damping

Rui Huang; Gregory G Howes; Andrew J McCubbin

doi:10.48550/arxiv.2401.16697

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The Velocity-Space Signature of Transit-Time Damping

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The Velocity-Space Signature of Transit-Time Damping

Rui Huang, Gregory G Howes and Andrew J McCubbin

arXiv.org

Cornell University

01/30/2024

DOI: 10.48550/arxiv.2401.16697

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Preprint (Author's original)This preprint has not been evaluated by subject experts through peer review. Preprints may undergo extensive changes and/or become peer-reviewed journal articles. 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, leading to the collisionless damping of electromagnetic waves and the resulting energization of those particles through the perpendicular component of the electric field, E⊥. In this study, we utilize the recently developed field-particle correlation technique to analyze 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 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 \Alfvenic waves, they are mediated by different forces and exhibit different behaviors as v⊥→0. We also explore how the dominant damping mechanism varies with ion plasma beta βi, showing that TTD dominates over LD for βi>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.

Physics - Plasma Physics

Details

Title: Subtitle: The Velocity-Space Signature of Transit-Time Damping
Creators: Rui Huang
Gregory G Howes
Andrew J McCubbin
Resource Type: Preprint
Publication Details: arXiv.org
DOI: 10.48550/arxiv.2401.16697
eISSN: 2331-8422
Publisher: Cornell University; Ithaca, New York
Language: English
Date posted: 01/30/2024
Academic Unit: Physics and Astronomy
Record Identifier: 9984554855402771

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