Talk:Plasma parameters

Other plasma parameters

I would suggest adding Lundquist number and Magnetic Reynolds number --Samoojas (talk) 19:49, 1 July 2011 (UTC)

Would we also be able to add the strong coupling constant (not yet an article for it that I can find, but it is defined as the ratio of energy due to the electric field to thermal energy. NJHartley (talk) 13:44, 19 July 2012 (UTC)

Electron gyrofrequency

I think the "c" in the gyrofrequency shouldn't be there. But I don't know much about plasma physics. Someone please, confirm. — Preceding unsigned comment added by 129.123.154.253 (talk) 01:36, 24 March 2014 (UTC)

It's there because the formula is in gaussian units and not SI ones. I think they ought to be converted, unless someone knows a good reason not to. --Ipatrol (talk) 20:39, 17 February 2019 (UTC)

The formula for ion gyroradius appears to have a constant error.

The formula for this is off by 10,000, which looks like a flipped sign on the exponent of the constant up front (should be 1.02*10^-2), and/or it was checked in B units of Gauss rather than Tesla as I believe it should, under (coincidentally) Gaussian CGS units. I have not checked the rest of the page for the same error.

   r_i = v_{Ti}/\omega_{ci} = 1.02\times10^2\,\mu^{1/2}Z^{-1}T_i^{1/2}B^{-1}\,\mbox{cm}  — Preceding unsigned comment added by Pjwitham (talk • contribs) 17:17, 27 August 2014 (UTC) 

Conditions for Plasma

I would suggest adding a section with the conditions necessary for a plasma to be achieved. For example:

– Debye Length must me smaller than any typical length of the system, otherwise significant charge separations could arise and the plasma becomes dominated by some boundary effects

– Debye length must be statistically valid => there should be enough particles in a Debye Sphere: $N=n(4/3)\pi \lambda _{D}^{3}\gg 1$ (where n is the average density of particles)

And some other relations. Heitorpb (talk) 17:06, 17 October 2015 (UTC)

All these conditions are required for a plasma to be called "ideal" in one sense or another. They can be violated. E.g., the condition for a large number of particles in the Debye sphere is violated – sometimes very strongly – in so called strongly coupled plasmas. The Plasma (physics) article discusses it at some length. Evgeny (talk) 22:01, 19 January 2022 (UTC)

Merger proposal with Electron temperature

Considering that the Electron temperature article needs some help, and that the electron temperature is one of the most fundamental plasma parameters, maybe it could appear as a subsection in this plasma parameter article instead? -- AquaDTRS (talk) 23:55, 4 September 2018 (UTC)

  Y Merger complete. Klbrain (talk) 11:25, 4 January 2020 (UTC)

Electron temperature is not a plasma parameter; it's a plasma property - like e.g., electron density or ion charge. One may argue about linguistic differences, but the meaning of "plasma parameter" in this article is quite definite, and temperature doesn't belong here. The main Plasma (physics) article has a dedicated "Temperature" section and a discussion about non-thermal plasmas. I suggest to remove the section here. If there is a content that is worth keeping (though I don't see any), it should be moved over there. Evgeny (talk) 21:54, 19 January 2022 (UTC)

Conversion to SI units

Most (or all?) of the formulas for the plasma parameters on this page have just been copied from the NRL plasma formulary. First of all, I think this should be mentioned more prominently, not just in the references section. Moreover, the cgs unit system used in the NRL formulary is outdated and should really no longer be used in physics articles. Many non-expert readers will not be familiar with conversion of units from the SI system to cgs. A non-expert might also not realize that electromagnetic quantities such as charge or magnetic induction not only have different values but also different dimensions in SI vs cgs unit systems. I would therefore suggest to convert all formulas to SI units except for the plasma temperature, which in plasma physics usually is expressed by its corresponding thermal energy in units of eV instead of k T (T in Kelvin, k the Boltzmann factor).

Density in particles per cubic centimeter is still quite common in heliophysics and astrophysics, as is ion mass in AMU not kilograms or grams. Because of that and for consistency with other Wikipedia articles, I think including equations in both SI and cgs would be preferable to converting everything to SI. Fcrary (talk) 22:28, 11 October 2020 (UTC)

electron plasma frequency factor seems to be wrong

electron plasma frequency const factor is given as 5.64e4 . Using the Si units of electron mass, charge etc, one arrives at 5.64e2 * n_e^(1/2) 185.82.160.26 (talk) 15:17, 18 August 2023 (UTC)

Note the first sentence: "All quantities are in Gaussian (cgs) units except energy and temperature which are in electronvolts." In particular, the density is in $\mathrm {cm} ^{-3}$. Evgeny (talk) 08:57, 20 August 2023 (UTC)

The presence of vacuum permittivity $\varepsilon _{0}$ in the equation is misleading. Vacuum permittivity in CGS is $1/4\pi$ (dimensionless), so the CGS equation for the electron plasma frequency should read

$\omega _{pe}=\left({\frac {4\pi n_{e}e^{2}}{m_{e}}}\right)^{\frac {1}{2}}.$

This is the exact expression given by the NRL Formulary cited in the article, and I have changed the equation in the article to reflect this. CoronalMassAffection (talk) 19:12, 21 August 2023 (UTC)