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UID:seminar-12735@staging.epss.ucla.edu
DTSTAMP:20260405T163302Z
DTSTART:20251205T033000Z
DTEND:20251205T043000Z
SUMMARY:How Alfvén Waves Drive Meso-Scale Structures in the Magnetosphere-Ionosphere System?
LOCATION:3853 Slichter Hall
DESCRIPTION:Date: 2025-12-05 00:00:00

Time: 3:30 - 4:30pm

Location: 3853 Slichter Hall

Presented By:
Sheng Tian

Abstract:
Alfvén waves\, named after the Nobel laureate Hannes Alfvén\, are a fundamental mode in magnetized plasmas. It has long been established that they play a key role in the energy circulation of the magnetosphere-ionosphere (M–I) coupling system. However\, their dissipation on meso- and small-scales is much less well understood. Here\, we examine how Alfvén waves drive several common meso-scale structures\, including the auroral arcs\, auroral beads\, and the magnetospheric cusp. We find that Alfvén waves\, although being the common energy source\, are dissipated differently among these structures. In the auroral arcs\, Alfvén waves power a quasi-static parallel electric field that accelerates ions away from and electrons toward the ionosphere. In the auroral beads\, electrons are accelerated directly by the wave’s own parallel electric field. In the cusp\, Alfvén waves significantly energize the outflowing ions\, presumably through perpendicular heating. These distinct energy conversion processes we have unveiled are important in understanding the meso-scale M–I coupling on Earth and other planets. Our results also raise important questions for future studies: How are these Alfvén waves generated? What additional dissipation mechanisms may be operating? Why are Alfvén waves dissipated differently\, and what are the controlling factors?
URL:https://staging.epss.ucla.edu/how-alfven-waves-drive-meso-scale-structures-in-the-magnetosphere-ionosphere-system/
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