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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-8198
DTSTART:20230213T180000Z
DURATION:PT1H0M0S
DTSTAMP:20260414T055039Z
LAST-MODIFIED:20230209T160319Z
LOCATION:2241 Chamberlin Hall
SUMMARY:Multiscale Nature of Turbulence in Space Plasmas \, Plasma Phy
 sics (Physics/ECE/NE 922) Seminar\, Yan Yang\, University of Delaware
DESCRIPTION:Turbulence enters into space plasmas in many guises. The c
 omplexity and variability of the behavior of plasma turbulence are in 
 large part due to the involvement of dynamics at many scales\, ranging
  from macroscopic fluid to sub-electron scales. Based on what plasma p
 roperties we are interested in studying\, be they dominant at small or
  large scales\, plasma can be treated as tractable models in various l
 imits\, such as the kinetic theory and magnetohydrodynamic (MHD) theor
 y. Turbulence flows are characterized by the nonlinear transfer of ene
 rgy and other quantities across a huge range of scales. Observed turbu
 lence in space is expected to involve cross-scale energy transfer and 
 subsequent dissipation and heating. Space plasmas are frequently taken
  to be weakly collisional or collisionless. Therefore\, an explicit fo
 rm of viscous dissipation as in collisional (e.g.\, MHD) cases cannot 
 be easily defined. A variety of approaches have attempted to character
 ize specific mechanisms (e.g.\, magnetic reconnection\, wave-particle 
 interaction\, and turbulent-driven intermittency) and to quantify the 
 dissipation. However\, the community has not come to a consensus solut
 ion applicable to all systems. In this talk I will first give an overv
 iew of some basic properties for turbulence. Then I will briefly revie
 w turbulence theory application in space plasmas. I will discuss in de
 tail how to disentangle multiscale properties\, how plasma dynamics br
 idges multiple scales\, what new ingredients are introduced in cross-s
 cale transfer as models progress from fluid to kinetic\, and how to id
 entify key steps in energy transfer and estimate energy dissipation ra
 te in weakly collisional plasmas. These also motivate several unresolv
 ed issues that may be addressed by future studies. Where feasible\, ex
 amples are given from MHD\, Particle in Cell\, and hybrid Vlasov-Maxwe
 ll simulations\, and from Magnetospheric Multiscale (MMS) observations
 . 
URL:https://www.physics.wisc.edu/events/?id=8198
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