- #1

- 793

- 17

I was wondering of those who might write papers in this field.

What is the convention of units in plasma physics papers, and is this often all screwed around and you have to already understand it to understand it?

I'll give you an example, because I am looking at this paper to understand thermalisation times-

https://descanso.jpl.nasa.gov/SciTechBook/series1/Goebel_AppF_Electron.pdf

In the opening line it says-

Spitzer derived an expression for the slowing-down time of test particles (primary electrons in our case) with a velocity

*v*= root[2

*Vp/m]*, where

*eVp*is the test particle energy....

So what units is that in? If it is cgs units, then is 'e' in MeV, yet the rest of the article references eV? Or maybe it is Rybergs? Or is it statcoulombs? None of those seem to work, MeV is the only unit that works for v in cm/s and Vp in eVs?

What am I missing here?

There is another paper I can link to later that also says it is cgs units, but if you feed in all the numbers in cgs and compare with the graph it shows in the paper, the axes are out by 3 OOM.

I get the impression, please do disabuse me of this idea, that much of plasma physics is 'theoretical' and the equations become sufficiently abstract that they lose all their constants and it is not possible to really know what system of units the equations represent, unless you already understand it.

Would I be overstating the case that any equation involving physical quantities should clearly state what units of measurement those physical variables use?

It is OK in most fields of physics of course, but when it comes to electricity and magnetism that plasma physics papers rel