Inertial Confinement Fusion

1
National Undergraduate Fellowship Program
in Plasma Physics and Fusion Engineering Plasma
Astrophysics Michael Brown Swarthmore
College June 2007 Outline Brief plasma review
(B-fields and MHD) Two important
paradigms Astrophysical objects (solar flares to
galactic jets) Astrophysical processes (dynamos,
reconnection and pulsars)
2
Astrophysical Plasma Review

• Magnetic fields
• related to electric fields by Lorentz
  transformation
• Q why are there large scale B-fields but no
  large scale E-fields in the universe?
• A ...there are lots of electric monopoles
  around to short out electric fields
• B-fields are associated with currents but do
  currents cause B-fields are vice-versa?
• exert forces on currents ForceJxB
• contain energy

3
Astrophysical Plasma Review
equations of MHD
Newton II
Ohms Law
Maxwells eqs
induction eq. (curl of Ohm)
4
Astrophysical Plasma Review
ramifications of MHD
5
Astrophysical Plasma Review

• Frozen-in Flux
• high conductivity Coulomb collisionality drops
  with T (so ? T-3/2)
• universe is an excellent conductor of electricity
  almost everywhere
• frozen-in flux
• assume perfectly conducting magnetofluid
• no electric field in a perfect conductor
• if field lines move with respect to fluid then
  an electric field is induced
• therefore fields move with the fluid!

6
Poynting Vector
7
Simple 2D Reconnection Theory (Sweet/Parker)
8
Reconnection Rate
where Rm is based on the Alfven velocity in the
bulk magnetofluid and on the largest scale of the
system L. Malf is a dimensionless measure of the
reconnection rate or the rate at which magnetic
field lines are annihilated or the direct
electric field. More sophisticated models
Petschek, 1964 and Vasyliunas, 1975 predict a
faster reconnection rate and a smaller ration of
uout/uin. It appears, however that a bound
exists