Department of Climate and Space Sciences and Engineering in the College of Engineering at the University of Michigan

CLaSP Seminar Series - Professor Stuart Bale

Date: January 12, 2017
Time: 3:30 pm - 4:30 pm
Location: Space Research Building Auditorium, Room 2246

Professor Stuart Bale, Director of the UC Berkeley Space Sciences Laboratory, will give a special seminar. 

Titile: "Alfven Wave Amplitude Limits in the Solar Wind"

Abstract: Shear-Alfven waves are the signature eigenmode of magnetized plasmas and 
are ubiquitous and fundamental in space and astrophysical plasmas.  Alfvenic 
processes are thought to play a fundamental role in particle acceleration, auroral 
processes, and magnetized  turbulent cascades amongst many other processes.
Recent theoretical work has uncovered a stringent nonlinear limit on the 
amplitude of linearly polarized shear-Alfven waves in high-beta collisionless plasmas.  

This limit is associated with a self-excited firehose instability.  We use 10 years 
of Wind spacecraft data to demonstrate the existence of this effect, and also show a 
low beta threshold that may be associated with parametric instability.  Finally, 
I will extrapolate these results to the inner heliosphere and discuss future 
measurements with Solar Probe Plus.