Science / Technology - Colloquium
Monday, November 24, 2008
4:00 PM-5:00 PM
Olin Hall
223
The study of Magnetohydrodynamic (MHD) linear stability with line-tying
has been the subject of intense research in the solar physics community
for several decades, in an attempt to understand the dynamics of solar
flares and the related mechanisms of energy release (see the review paper
[1]). Moreover, recent experiments on two cylindrical devices [2-3] have
brought even further interest on this subject. It is important to notice,
however, that applications to solar physics or to laboratory experiments
span a wide range of values of the Lundquist number S (proportional to the
inverse of plasma resistivity), S>10^10 in the solar corona while S~50 for
the experiments. In this presentation, I will therefore analyze the effect of plasma resistivity on line-tied modes in cylindrical geometry and discuss the
existence of tearing modes in line-tied plasmas [4]. Tearing modes occur in a plasma due to plasma resistivity. They are commonly associated to boundary layers and have growth rates proportional to a fractional power of plasma resistivity. Whether they can exist in a line-tied plasma has been matter of debate for a long time. I will show that the physics of line-tying prevents the existence of tearing modes and the only resistive unstable modes left in the plasma have a (much smaller) growth rate proportional to plasma resistivity.
Cost: FREE
Sponsored by: WPI Physics Department, Dr. Izabela Stroe
Suggested Audiences: College
E-mail:
izabela@wpi.edu
Phone: 508-831-5249
Last Modified: November 21, 2008 at 1:41 PM
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