[IGPP Everyone] SPACE PHYSICS SEMINAR - Fall Quarter - Friday October 9, 2020 - 3:30pm - UCLA Zoom

[Marjorie Sowmendran]

SPACE PHYSICS SEMINAR 



ZOOM LINK PROVIDED BELOW 








https://ucla.zoom.us/j/93382900867?pwd=TlVQRmZyVEJFa0FCZWlRMU0yREtjUT09 







Date/Time: October 9, 2020/ 03:30 PM Pacific Time (US and Canada) 







SPACE PHYSICS SEMINAR 

DEPARTMENT OF EARTH, PLANETARY, AND SPACE SCIENCES 

DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCES 

UNIVERSITY OF CALIFORNIA, LOS ANGELES 



Turbulence and switchbacks in the solar wind: theory and observations 




Anna Tenerani, 


Dept. of Physics, U. of Texas, Austin 





Alfvénic fluctuations represent the dominant contributions to turbulent fluctuations in the solar wind, especially, but not limited to, the fastest streams with velocity of the order of 600-700 km/s. Alfvénic fluctuations can contribute to solar wind heating and acceleration via wave pressure and turbulent heating. Observations show that such fluctuations are characterized by a nearly constant magnetic field amplitude, a condition which remains largely to be understood and that may be an indication of how fluctuations evolve and relax in the expanding solar wind. Interestingly, measurements from Parker Solar Probe have shown the ubiquitous and persistent presence of the so-called switchbacks. These are magnetic field lines which are strongly perturbed to the point that they produce local inversions of the radial magnetic field. The corresponding signature of switchbacks in the velocity field is that of local enhancements in the radial speed (or jets) that display the typical velocity-magnetic field correlation that characterizes Alfvén waves propagating away from the Sun . After reviewing the main properties of Alfvénic fluctuations and switchbacks in the solar wind, we will address how their stability and nonlinear evolution is affected by nonlinearities and kinetic effects in different plasma beta regimes. Emphasis will be given to the onset and evolution of parametric instabilities and to the impact of kinetic effects on their saturated nonlinear state. 


Friday, October 9, 2020 

3:30 - 5:00 PM 



In-Charge: Marco Velli 









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