Thickness of 'shell' in momentum space in a plasma?

[Sven Andersson]

Let's say we have a plasma of protons or deuterons and electrons; how thick is the 'shell' that the nuclei form in momentum space compared to the 'shell' formed by D2 or H2 in a gas, at room temperature? Will the distribution of momentum be more spread out or more compact, so to speak, in a plasma compared to a gas?

 

[mfb]

To have a hydrogen plasma at room temperature in thermodynamic equilibrium it has to be extremely thin.
The distribution of kinetic energies will be the same, so the nuclei/atoms will have very similar momenta. The electrons have a much lower momentum for the same energy as they are lighter.