# Plasma energy

1. Nov 17, 2007

### Heimdall

Hi,

Let's consider a plasma of 3 distinct populations : 1 cold proton population of 0.2 density, 1 hot proton population of 0.8 density, and one electron population.

I have $$T_i=T_e$$ and I set the velocity of my cold population to 0. I expected that te energy of my hot proton population to be equal to the energy of my electron population, but in fact the electrons are always a bit mor energetic than my protons.

Am I right, should I expect the energies to be equal ?

2. Nov 17, 2007

### Staff: Mentor

Having distinct cold and hot populations of protons would be rather impossible - there is usually continuous distribution. The electrons would rapidly equilibrate to the proton temperatures since the electrons are much lighter and the coulomb forces are considerable. The electrons temperatures are approximately those of the protons for those reasons, and perhaps slightly cooler since electrons lose energy more readily due to brehmsstrahlung, and if magnetically confined, cyclotron radiation.

Only with external heating (e.g. RF) would electrons be hotter - but only while the external heating is applied.