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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:1
UID:UW-Physics-Event-8449
DTSTART:20231009T170000Z
DTEND:20231009T181500Z
DTSTAMP:20260414T013404Z
LAST-MODIFIED:20231003T182147Z
LOCATION:1610 Engineering Hall
SUMMARY:“Some Recent Developments of Compressible MHD Turbulence wit
 h Applications to Space and Astrophysical Plasmas”  \, Plasma Physic
 s (Physics/ECE/NE 922) Seminar\, Hui Li\, Los Alamos National Laborato
 ry
DESCRIPTION:<br>
\nin collaboration with K. Yuen\, S. Du (LANL)\; Z. G
 an\, X. Fu (NMC)\, H. Yan (DESY)<br>
\n <br>
\nRecent Parker Solar Pro
 be (PSP) measurements of the near-Sun solar wind have provided in-situ
  measurements of compressible magnetized turbulence. Understanding the
 ir properties has led us to examine several physical processes includi
 ng the temporal properties of compressible MHD turbulence\, scalings o
 f density fluctuations and the magnetic energy dissipation via compres
 sible effects in reconnecting regions. Specifically\, through 4D FFT a
 nalysis (temporal plus 3D spatial) of compressible MHD turbulence\, mo
 st fluctuations are found to have very low frequencies with finite wav
 enumbers and they do not follow the dispersion surfaces of linearized 
 MHD waves. We propose a broadened Lorentzian model in frequency depend
 ence and find quite good agreement between the theory and simulations 
 (Yuen et al. 2023). One implication of this understanding is the re-ex
 amination of the mechanisms responsible for density fluctuations in co
 mpressible turbulence\, along with the properties observed by PSP (Fu 
 et al. 2023).  In addition\, we present simulations of 3D reconnection
  to demonstrate that the compressible processes give rise to an additi
 onal phase that produces even more overall magnetic energy conversion 
 than that by the initial relaxation of magnetic curvature (Du et al. 2
 022). These processes could play a role in the continued heating of th
 e background plasma such as solar wind and magnetized outflows.
URL:https://www.physics.wisc.edu/events/?id=8449
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