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PRODID:UW-Madison-Physics-Events
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SEQUENCE:2
UID:UW-Physics-Event-6691
DTSTART:20211004T170000Z
DURATION:PT1H0M0S
DTSTAMP:20260414T192159Z
LAST-MODIFIED:20210926T212359Z
LOCATION:2241 Chamberlin Hall
SUMMARY:The onset of magnetic reconnection in collisional and collisio
 nless plasmas\, Plasma Physics (Physics/ECE/NE 922) Seminar\, Nuno Lou
 reiro (MIT)
DESCRIPTION:Magnetic reconnection events are transient phenomena: a re
 latively quiescent plasma suddenly transitions to a reconnecting state
  where large amounts of magnetic energy are released. This sharp trans
 ition is known as the onset of magnetic reconnection. Analytical and n
 umerical studies of reconnection often focus on assumed post-onset con
 figurations and plasma parameters\, by-passing not only the onset tran
 sition\, but also the question of how such configurations came to be  
 — and\, perhaps more pertinently\, of whether they are even physical
 ly realizable. For example\, we now know that large-scale Sweet-Parker
 -like current sheets cannot form dynamically because they are subject 
 to the super-Alfvénic plasmoid instability. Similar issues arise in c
 ollisionless plasmas\, where the natural evolution of a given system l
 eading to the formation of current sheets can trigger a variety of ins
 tabilities before such sheets reach electron scales. These notions imp
 ly that the onset of reconnection can be obtained by following the cur
 rent sheet formation process and its transition from a stable to an un
 stable system. Moreover\, I will argue that\, because instabilities ar
 e inevitably triggered during the current sheet formation process\, th
 e (nonlinear) reconnection stage cannot be trivially decoupled from th
 e current sheet formation stage\; for example\, the parameters charact
 erizing the reconnection event may depend critically on the formation 
 process and the instabilities that arise then. I will illustrate these
  issues both in the MHD and the kinetic regimes.
URL:https://www.physics.wisc.edu/events/?id=6691
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