[Mesa-users] The plasma interaction parameter

[Ana Brito]

Hi Evan,

So, gam it's the ionic parameter! Thank you!
I attached a new figure where I took into account the factor zbar^(5/3).
The two lines are much closer now but there is still a difference.

Best regards,

Ana

On Mon, Nov 23, 2020 at 9:46 PM Evan Bauer <evan.bauer.astro at gmail.com>
wrote:

> Hi Ana,
>
> The quantity "gam" in the profile output is the plasma interaction
> parameter for ions rather than electrons, so it differs from \Gamma_e by a
> factor of approximately zbar^(5/3). Does that explain the difference that
> you're seeing?
>
> Cheers,
> Evan
>
> > On Nov 23, 2020, at 3:23 PM, Ana Brito via Mesa-users <
> mesa-users at lists.mesastar.org> wrote:
> >
> > Dear MESA users,
> >
> > I have a question about the plasma interaction parameter.
> >
> > This parameter can be computed using using the expression:
> >
> > \Gamma_e = \frac{e^2}{d k_B T}
> > where
> > d = ( \frac{3}{4 \pi n_e} )^{1/3}.
> > (e is the electron charge, k_B the Boltzmann constant, T the temperature)
> > The electron density, n_e, can be obtained from ye (the electron to
> baryon ratio), one of the profile columns options:
> > n_e = ye*rho*AV.
> > Here, rho is the density, and AV the Avogadro number.
> >
> > In the figure attached I represented this \Gamma_e with a black line for
> a 1 solar mass main-sequence stellar model. Later I noticed that the plasma
> interaction parameter is itself a profile output option. The \Gamma_e
> obtained directly from the profile output is represented in the same figure
> with a blue line. These two lines do not match. There is a difference
> between them that I don't know how to explain. Maybe I'm doing something
> wrong with the electron density.
> > My question is: what could be the cause of this difference between black
> and blue lines?
> >
> > I am also sending attached the inlist used under MESA v12115.
> >
> > Thank you very much!
> >
> > Best regards,
> >
> > Ana
> >
> <inlist_solarmass1><starting1.mod><Gamma_e.png>_______________________________________________
> > mesa-users at lists.mesastar.org
> > https://lists.mesastar.org/mailman/listinfo/mesa-users
> >
>
>
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