Formation of Rolling‐Pin Distribution of Suprathermal Electrons Behind Dipolarization Fronts. Issue 1 (10th January 2022)

• Record Type: Journal Article
• Authors: Fu, W. D.; Fu, H. S.; Cao, J. B.; Yu, Y.; Chen, Z. Z.; Xu, Y.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 1(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-01-10
• Subjects: rolling‐pin distribution -- suprathermal electrons -- dipolarization fronts (DFs); Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1029/2021JA029642
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: The rolling‐pin distribution of suprathermal electrons, exhibiting electron pitch angles primarily at 0°, 90°, and 180°, receives attention in both observations and simulations recently. However, its formation mechanism has rarely been studied. In this work, we report an observation of such distribution with two substructures behind the dipolarization front (DF) and reveal that only Fermi mechanism is contributory to suprathermal electron acceleration. We present a new explanation for its formation. The Fermi mechanism accelerates parallel and antiparallel suprathermal electrons, the spatially varying magnetic bottles control the emergence of perpendicular electrons, and electrons whose pitch angle around 45° and 135° drift away in the middle magnetotail. Under the combination of these mechanisms, the rolling‐pin distribution with two substructures is formed behind DFs. This formation mechanism is useful to understand the electron dynamics behind DFs. Key Points: A rolling‐pin distribution exhibited two substructures behind the dipolarization front Only suprathermal electrons in parallel and antiparallel directions were accelerated Fermi acceleration, magnetic mirror effect and magnetic gradient/curvature drift contribute to the formation of such distribution jointly