[Triumf-seminars] TRIUMF Special Seminar, Tue 2010-05-04 at 14:00

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Date/Time: Tue 2010-05-04 at 14:00  

Location: Auditorium  

Speaker: Dr. Antoine Cerfon - Hausser Fellowship finalist (MIT)  

Title: 'Are fusion plasmas compressible? (and why do we care)'  

Abstract: Dr. Cerfon is a candidate for the TRIUMF Otto Ha"usser Fellowship.

'One of the most promising approaches to controlled nuclear fusion is to use
magnetic fields to confine the hot nuclear fuel in the plasma state. This has
led to impressive achievements over the past fifty years, but there are
technical difficulties that must be resolved for fusion energy to become a
practical reality. In particular, it is crucial to find ways to prevent the
violent, macroscopic plasma instabilities which can lead to major disruptions
and damage the fusion reactor.

The most commonly used model to understand the macroscopic behavior of plasmas
is Ideal MagnetoHydroDynamics (Ideal MHD), which describes the plasma as a
magnetized, compressible fluid. In this model, plasma compressibility
stabilizes some macroscopic modes, and several fusion reactors are designed to
rely explicitly on this type of stabilization. The problem is that Ideal MHD
assumes the plasma is highly collisional, whereas fusion grade plasmas are at
such high temperatures they are essentially collisionless. It is therefore
crucial to reevaluate the compressibility stabilization result using more
reliable models in the regime of fusion interest.

In this talk, I will introduce three new models for collisionless plasmas: one
fluid model and two kinetic models. Using energy variational principles,  I
will analyse plasma compressibility in these three models and compare with
Ideal MHD. The outcome is surprising: wave-particle resonances, only accounted
for in kinetic models, actually cancel the apparent compressibility
stabilization. In other words, fusion grade plasmas are inherently
incompressible! I conclude by discussing how this new result may affect the
design of future fusion reactors.'
  

Dr. Cerfon and Dr. Crawford are the two finalists for the TRIUMF Otto Hausser Fellowship.