BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:4
UID:UW-Physics-Event-8498
DTSTART:20240920T203000Z
DTEND:20240920T213000Z
DTSTAMP:20260415T034241Z
LAST-MODIFIED:20240916T140941Z
LOCATION:Chamberlin 2241
SUMMARY:Exploring Magnetic Reconnection With Phase Space Measurements\
 , Physics Department Colloquium\, Earl Scime\, West Virginia Universit
 y
DESCRIPTION:One of the “Grand Challenges” of plasma physics is to 
 understand the processes whereby energy stored in the magnetic fields 
 of a plasma is converted into kinetic energy of the ions and electrons
  in the plasma. We see that this energy conversion happens in stars\, 
 in planetary magnetospheres\, and in fusion plasmas. Over the past few
  decades\, there has been considerable progress in developing theoreti
 cal models of magnetic reconnection\, the process responsible for the 
 energy conversion. Measurements from spacecraft and in laboratory expe
 riments have also contributed to our understanding of magnetic reconne
 ction in collisional and collisionless plasmas. Recently\, a variant o
 f magnetic reconnection in which ions do not participate and the physi
 cs is dominated by electron dynamics has been identified in space meas
 urements – “electron-only reconnection.” I will review the exper
 imental evidence for electron-only reconnection in space and the state
  of our computational and theoretical understanding of this process. I
  will also describe recent studies of electron-only reconnection in th
 e PHAse Space MApping (PHASMA) experiment at West Virginia University.
  In PHASMA\, two magnetic flux ropes are driven together to initiate t
 he reconnection process and advanced\, non-perturbative diagnostics pr
 ovide direct measurements of the electron and ion velocity distributio
 n functions at the kinetic scale (at scales smaller than the gyro moti
 on of the charged particles around the magnetic field). We find that\,
  consistent with theoretical predictions\, the majority of incoming ma
 gnetic energy appears as electron thermal energy and that Ohmic proces
 ses are unlikely to be responsible for the measured increase in electr
 on enthalpy. The electron velocity distribution function measurements 
 include non-Maxwellian features\, including beams that jet out from th
 e X-point in both outflow directions. We observe that the electron bea
 m speed scales with the local electron Alfvén speed and that the spat
 ial distribution of the electron heating matches theoretical predictio
 ns. Measurements of the three-dimensional electron velocity distributi
 on function (a unique capability of the PHASMA facility) confirm that 
 the most likely mechanism for the electron heating is the parallel ele
 ctric field created in the reconnection process.
URL:https://www.physics.wisc.edu/events/?id=8498
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