Limitations

While these similarity transformations capture some basic properties of plasmas, not all plasma phenomena scale in this way. Consider, for example, the degree of ionization, which is dimensionless and thus would ideally remain unchanged when the system is scaled. The number of charged particles per unit volume is proportional to the current density, which scales as x^-2, whereas the number of neutral particles per unit volume scales as x^-1 in this transformation, so the degree of ionization does not remain unchanged but scales as x^-1.

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The first thing to notice is that many cosmic phenomena cannot be reproduced in the laboratory because the necessary magnetic field strength is beyond the technological limits. Of the phenomena listed, only the ionosphere and the exosphere can be scaled to laboratory size. Another problem is the ionization fraction. When the size is varied over many orders of magnitude, the assumption of a partially ionized plasma may be violated in the simulation. A final observation is that the plasma densities needed in the laboratory are sizeable, up to 10¹⁶ cm^-3 for the ionosphere, compared to the atmospheric density of about 10¹⁹ particles per cm³. In other words, the laboratory analogy of a low density space plasma is not a “vacuum chamber”, but laboratory plasma with a pressure, when the higher temperature is taken into consideration, which can approach atmospheric pressure.

The citations of which seem to range from 1941 to 1966. Surely such an exciting field has seen more recent activity?

… it is well known that electromagnetic phenomenon is scale independent up to 14 orders of magnitude and, in fact, no limit to electromagnetism’s scalability has been identified.
See the link below and please scroll down to the bottom of the page to note the peer-reviewed published papers supporting plasma’s scalability.
plasma-universe.com/index.php/Plasma_scaling

That article was plagiarized verbatim from Plasma Scaling — Wikipedia (click on my name for the link), and stopping short of “Dimensionless parameters in tokamaks”.

Sit down, again. I’ll get back to you later, after I’ve listend to more serious stuff

I was talking about neutral hydrogen… the hydrogen is not neutral in stars…. (just to make that clear to some other folks…)

But, you are right about the other thing: Photons are the transmitters of the em-interaction. I wonder, why those guys never talk about this one