Talk:Plasma scaling

General
In the section Cosmic application what does this sentence refer to: The consequence of this is that charged particles moving in very highly magnetised space plasmas, are somewhat different to what is seen in the laboratory

I think this refers to magnetic fields in space being significantly greater than that which can be reproduced in the laboratory. --Iantresman 10:59, 21 December 2005 (UTC)

In the section Dimensionless parameters in tokamaks what are these parameters: The remaining (dimensional) parameters can be taken to be n, T, B, and R.

I find the subject of this article highly interesting, but it is badly written; I hope someone would improve it to the point of a stand-alone encyclopedia article. --DelftUser 19:34, 14 December 2005 (UTC)

Dimensinos of parameters...
In base dimensions the parameters are:

Particle density n: has dimension 1/length3

The temperature T: has dimension thermodynamic_temperature

The magnetic field B: has dimension mass/(electric_current*time2)


 * β ~ nTB-2

There is no way that β has dimension 1. --DelftUser 19:07, 20 December 2005 (UTC)


 * The above expression only gives the scaling. In SI units the full expression is
 * $$\beta = \frac{nk_BT}{B^2/2\mu_0}$$.
 * To sort out the dimensions, remember that
 * $$\nabla\times B/\mu_0 = \frac{\partial D}{\partial t} + j$$,
 * so B/&mu; has dimensions of charge/length/time, and
 * $$m\frac{dv}{dt} = qv\times B$$,
 * so B has dimensions of mass/charge/time (in agreement with your expression). Together this gives for B2/2&mu;0 dimensions of mass/length/time2. Since kBT is an energy (mass*length2/time2), nkBT also has dimensions of mass/length/time2. Therefore &beta; is dimensionless. --Art Carlson 08:56, 21 December 2005 (UTC)


 * Thanks. Is there an article in Wikipedia where β, and the other dimensionless parameters, are defined? If not could you consider adding the definitions to the article. --DelftUser 18:35, 21 December 2005 (UTC)


 * Plasma (physics) --Art Carlson 20:42, 21 December 2005 (UTC)

refs for section Dimensionless parameters in tokamaks
I'm afraid I wrote most of that section, but it has been some time and I couldn't say anymore where my info came from. I think most of it can probably be found in Application of dimensionless parameter scaling techniques to the design and interpretation of magnetic fusion experiments, but that is not light reading. Art Carlson (talk) 15:58, 25 May 2012 (UTC)
 * thanks for the quick answer ! A 88 pages review paper isn't indeed a light reading ! Do you confirm that the 3 dimensionless parameters in the paper are the 3 first of table 3 (p12), and that they are good reason to ommit the 2 next (q and M) in the following discussions? (the last 4 seem obvious to me).
 * Do you also confirm that the discussions about varying ρ∗ is closely linked to the section 3.3 ρ∗ scaling experiments (p17 of the paper) ? Frédéric Grosshans (talk) 16:36, 25 May 2012 (UTC


 * Well, considering that paper was published in 2008, and the section 'Dimensionless parameters in tokamaks' was created some time in 2005, I'm going to go ahead and go out on a limb here and say that no, the information in that section did not come from that paper. -- DrBurningBunny (talk) 02:33, 7 November 2020 (UTC)

Question concerning "A commonly used similarity transformation"
In the section "A commonly used similarity transformation", it would help to have a motivating sentence before the long chain of deductions starts.

For example, can the reader assume that the basic rescaling is a rescaling of length, given by the ratio x, then view the others as flowing from that? 89.217.22.3 (talk) 09:21, 8 November 2014 (UTC)

Question concerning "Limitations"
The objection in this section seems to be so strong that it makes it look not like a scaling, but a mistake.

A scaling transformation should take solutions to solutions. Is this really possible if the ionization ratio changes? Or are all plasma scaling transformations only approximate?

(But only in the sense that the linear function x is approximately constant...) 89.217.22.3 (talk) 09:27, 8 November 2014 (UTC)

Why is this plasma scaling not part of plasma
Why is this plasma scaling not part of plasma (physics) ? It should be clearer in the intro. Needs a hatnote, or convert to a disambiguation ? It looks like a non standard use of the term "plasma scaling" - as in scaling laws in tokamak design. - Rod57 (talk) 12:19, 28 June 2022 (UTC)