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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:1
UID:UW-Physics-Event-9477
DTSTART:20251105T170000Z
DTEND:20251105T190000Z
DTSTAMP:20260413T083906Z
LAST-MODIFIED:20251022T205550Z
LOCATION:Chamberlin 5310
SUMMARY:Laboratory Investigation of Collisionless Kinetic Effects and 
 3D Topological Triggers for Magnetic Reconnection\, Thesis Defense\, P
 aul Gradney
DESCRIPTION:Magnetic reconnection is a fundamental plasma process resp
 onsible for the rapid conversion of magnetic energy into particle ener
 gy. This process occurs ubiquitously in astrophysical\, space\, and la
 boratory plasmas\, including solar flares\, Earth's magnetosphere\, an
 d fusion devices. Despite its importance\, key questions remain\, incl
 uding how reconnection dynamics are modified in the collisionless kine
 tic regime\, and what mechanisms trigger fast reconnection in three-di
 mensional (3D) systems as they transition from stable or quasi-stable 
 magnetic configurations to configurations that enable rapid energy rel
 ease.<br>
\n<br>
\nThis thesis presents experimental studies of collis
 ionless magnetic reconnection using the Terrestrial Reconnection EXper
 iment (TREX) at the Wisconsin Plasma Physics Laboratory (WiPPL). To mi
 nimize collisional effects and access the kinetic regime relevant to s
 pace plasmas\, a reconnection Drive Cylinder was developed. This syste
 m increases both the effective system size and the driving rate of rec
 onnection\, enabling TREX to reach a regime where electron dynamics ar
 e dominated by kinetic rather than collisional processes. Technical de
 tails of the Drive Cylinder design\, including its coil configuration 
 and magnetic field shaping\, are presented along with measurements of 
 its performance.<br>
\n<br>
\nUsing the 3-coil TREX configuration\, th
 e dynamics of 3D reconnection were investigated in a laboratory-genera
 ted mini-magnetosphere. Observations demonstrate that the explosive on
 set of reconnection can be triggered by a bifurcation of the magnetic 
 topological structure. In particular\, the rapid approach and crossing
  of separatrix surfaces led to the bifurcation of magnetic null points
 \, restructuring of separator lines\, and a marked increase in the rec
 onnection electric field along the separator. These results provide ex
 perimental evidence that geometric reconfiguration of a 3D magnetic to
 pology can initiate the onset of fast reconnection. The findings have 
 broad implications for understanding space weather\, astrophysical exp
 losions\, and relaxation events in magnetically confined laboratory pl
 asmas.
URL:https://www.physics.wisc.edu/events/?id=9477
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