[Everyone] Plasma Seminar TODAY 1pm: The Origin of Kinetic Turbulence in the Solar Wind (H. Che, NASA GSFC)

[Emmanuel V. Masongsong]

FYI, see below.  The BAPSF facility is in the UCLA Rehab building behind lot 32, near Kinross/Veteran Ave.  
There is also a P&A plasma seminar this Friday 1pm, see bottom of the email.

----- Forwarded Message -----
From: "Seth E Dorfman" <sethd at physics.ucla.edu>
Subject: Plasma Seminar TODAY: The Origin of Kinetic Turbulence in the Solar Wind

Dear all,

We have a plasma seminar TODAY Wednesday, May 21st at 1PM in the BAPSF 
auditorium (15-17 Rehab Building).  Pizza is at 12:30PM in the small 
conference room next door.  Our speaker is Dr. Haihong Che of NASA 
Goddard Space Flight Center, and her title and abstract are as follows:

"The Origin of Kinetic Turbulence in the Solar Wind"

Wind and outflow phenomena are common in astrophysical environments, 
such as in stars, supernovae, neutron stars as well as in normal 
galaxies and AGNs. The Sun provides the best laboratory to study 
important physical process in wind, such as turbulent transport and 
heating. Solar wind is the neutral charged plasma that escaped from 
solar corona and travels in space with velocity at hundreds of 
kilometers per second. Solar wind not only carries momentum but also 
advects fluctuations from the corona. The magnetic fluctuations in solar 
wind caused by solar activity such as solar flares can influence the 
environment of the Earth through interactions between magnetosphere and 
solar wind. Observations of magnetic fluctuations in the solar wind show 
that the power spectra of low frequency magnetic fluctuations on large 
scale approximately follow the Kolmogorov scaling law. However, a 
power-law spectra break at a high frequency appears to correspond to ion 
inertial length, a kinetic scale where ions demagnetize and decouple 
from electrons. These observations disfavor the long-held belief that 
the magnetic fluctuations on small kinetic scales come from the energy 
cascade of large scale Alfvenic turbulence, which predicts the frequency 
breakpoint should occur on scales that correspond to ion gyro-radius. On 
kinetic scales, wave-particle interactions dominate and lead to particle 
acceleration and heating, MHD theory becomes insufficient and a full 
kinetic treatment is required. What physical processes drive kinetic 
turbulence has been a puzzle for decades. In this talk, I will introduce 
a new idea for the origin of kinetic turbulence —that the kinetic 
turbulence and electron heating of solar wind originate from the inner 
corona. The idea is based on observations of nanoflares and accelerated 
electron beams from hundreds of eV to hundreds of keV in the corona. 
With particle-in-cell simulations, we found that the relative drift 
between nano-flare accelerated electron beams and the background core 
electron population drives a strong two-stream instability. The 
nonlinear evolution of the two-stream instability produces 
electromagnetic Weibel-like instability and give rise to kinetic 
Alfvenic wave and whistler wave turbulence through wave-wave 
interactions and forward and inverse energy cascades. At the same time, 
strong electron heating and Langmuir waves are produced. This model not 
only naturally produces the power spectra of kinetic turbulence and the 
relevant observations, but also simultaneously produces the electron 
heating in the solar wind. The generation of Langmuir waves can produce 
type III micro-radio bursts that resemble the well-studied type III 
bursts observed in solar flares.

http://www.pa.ucla.edu/sites/default/files/plasma_Che52114_flyer.pdf


___________________________________________________
FRIDAY MAY 23rd 1pm

"Turbulent processes in laboratory and natural plasmas: Connecting the dots"


Just a reminder: we have a plasma seminar this Friday, May 23rd at 1PM
in Room 4-330 of the Physics & Astronomy Building (PAB).  Pizza is at
12:30PM on the 4th floor of PAB.  Our speaker is Dr. Frank Jenko of the
Max Planck Institute for Plasma Physics, and his title and abstract are
as follows:

"Turbulent processes in laboratory and natural plasmas: Connecting the dots"

It is widely recognized that turbulence is an important and exciting
frontier topic of both basic and applied plasma physics - as well as of
many neighboring fields of science. Numerous aspects of this
paradigmatic example of nonlinear multiscale dynamics remain to be
better understood.

Meanwhile, for both laboratory and natural plasmas, an impressive
combination of new experimental and observational data, new theoretical
concepts, and new computational capabilities (on the brink of the
exascale era!) have and will become available. Thus, we are facing a
unique window of opportunity to push the boundaries of our grasp of
plasma turbulence.

In this context, a main goal is to further unravel its crucial role in
phenomena like cross-field transport of mass, momentum, and heat,
particle acceleration and propagation, plasma heating, magnetic
reconnection, or dynamo action. I will describe recent advances and
future challenges in this vibrant area of research, focusing on novel
insights into the redistribution and dissipation of energy in turbulent
plasmas at kinetic scales.

http://www.pa.ucla.edu/sites/default/files/plasma_Jenko52314_flyer.pdf