# How is energy shared in plasma between particles and photons?

1. Jun 24, 2011

### Spinnor

Suppose I had some plasma in box with walls that allowed nothing thru, photons, plasma, energy. Now heat the plasma and maintain some temperature T (ignore the difficulty in heating the plasma with the above walls, just assume you can). An approximation to this might be some small region of the sun at temperature T and nearly in equilibrium?

I assume at constant T there is an equilibrium where just as many photons are absorbed as are emitted?

How will the total kinetic energy in the plasma compare to the total energy in photons?

Thanks for any help!

2. Jun 25, 2011

### Spinnor

At equilibrium the kinetic energy in the plasma at given T goes as the density of the plasma while the energy density of the photons just depends on the temperature T?

Thanks for any help!

3. Jun 26, 2011

### ardie

by restricting heat transfer between the object and the universe, the total energy inside the object is constant. heating the system can have 2 possibilities.
1 - adding more photons to the system
2 - redistributing the system such that the enthropy increases
there will be some well defined temperature T at which the total number absorbed and emitted are equal, and thats the thermal equilibrium of the system. it will depend only on the temperature of the system.
the complete description of the particles is then a function of the enrthropy, the temperature and the number of particles in the plasma.