BEGIN:VCALENDAR
VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-4997
DTSTART:20190225T180500Z
DURATION:PT1H0M0S
DTSTAMP:20260419T084843Z
LAST-MODIFIED:20190117T212302Z
LOCATION:2241 Chamberlin Hall
SUMMARY:Quantifying heating by magnetic pumping through in situ spacec
 raft observations\, Plasma Physics (Physics/ECE/NE 922) Seminar\, Emil
 y Lichko \, UW Madison
DESCRIPTION:Superthermal electrons and ions in power-law tails are obs
 erved throughout the universe in a variety of astrophysical systems\, 
 but how these particles are energized is an open question. It is well 
 known that plasma can be heated by waves\, but most theories of partic
 le energization are based on wave-particle resonances which are only e
 ffective at particle velocities near the phase velocity of the wave\, 
 v ~ ω/k. Starting from the drift kinetic equation\, we have derived a
  magnetic pumping model\, similar to the magnetic pumping well-known i
 n fusion research\, where particles are heated by the largest scale tu
 rbulent fluctuations. We have shown that this is a complementary heati
 ng mechanism to the turbulent cascade in the solar wind\, effective up
  to v ≤ ω/k\, which results in power-law distributions like those o
 bserved in the solar wind [1]. However\, compressional Alfvénic turbu
 lence has the ability to magnetically trap superthermal particles. Mag
 netic trapping renders magnetic pumping an effective Fermi heating pro
 cess for particles with v >> ω/k\, and produces superthermal power-la
 w distributions. To test this\, we used satellite observations of the 
 strong\, compressional magnetic fluctuations near the Earth's bow shoc
 k from the Magnetospheric MultiScale (MMS) mission and found strong ag
 reement with our model. Given the ubiquity of such fluctuations in dif
 ferent astrophysical systems\, this mechanism has the potential to be 
 transformative to our understanding of how the most energetic particle
 s in the universe are generated.
\n[1] E. Lichko\, J. Egedal\, W. Daug
 hton\, and J. Kasper. Astrophys. J. Lett. 2\, 850 (2017)
URL:https://www.physics.wisc.edu/events/?id=4997
END:VEVENT
END:VCALENDAR