On the heat flux in collisional plasmas

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On the heat flux in collisional plasmas
Filippo Pantellini (LESIA)
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What is a collision ?
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Force acting on the proton in a uniform stream of
electrons
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Just truncate the integral
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Close encounter strong deflection is inevitable
Distant encounter with screening particles
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Characterization of a plasmas using the coupling
parameter or the Coulomb logarithm
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Plasmas in space and laboratory
R.D Petrasso, 1990
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The distribution function
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The general equation of motion
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Equation for the collisionless case
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Equation for the collisional case (1)
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(2)
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(No Transcript)
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Example of weakly coupled plasma the solar
atmosphere
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Example of a moderately coupled plasma the
solar convection zone
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Setup for a numerical heat flux experiment
Beck Pantellini, 2007
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Electron heat flux in steep temperature
gradient Maxwellian boundaries (A. Beck 2007)
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Conclusions

• Plasmas are not always collisionless
• Plasmas are not always weakly coupled (e.g.
  Solar convective zone)
• Many-body simulations are the only way to
  explore moderately coupled plasmas
• The heat flux may sometimes be close to the
  classical (Spitzer), even in steep temperature
  gradients and in moderately coupled plasmas.
• Point I did miss during preparation of this
  slide.

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The End