Equilibrum or non-equilibrum plasma?

[Moreno]

Is plasma heated to 2000-3000 C and composed of H+ and OH- ions equilibrium or non equilibrium plasma?

[John Cuthber]

Non equilibrium

Why do you ask?

[Moreno]

8 hours ago, John Cuthber said:

Non equilibrium

Why do you ask?

Why exactly? I'm interested in MHD generators. How we define equilibrium or non-equilibrium plasma?

[John Cuthber]

At only 3000 degrees the water wouldn't be fully dissociated. Even if it were, there would be other products- notably the neutral H2 and O2 molecules, and their ions and radicals like OH.

Having only 2 products would be a very odd state of affairs; the equilibrium would be different.

Do you understand this sort of thing?

https://en.wikipedia.org/wiki/Chemical_equilibrium

https://en.wikipedia.org/wiki/Anisothermal_plasma

[Moreno]

On ‎11‎/‎18‎/‎2017 at 5:22 PM, John Cuthber said:

At only 3000 degrees the water wouldn't be fully dissociated. Even if it were, there would be other products- notably the neutral H2 and O2 molecules, and their ions and radicals like OH.

Having only 2 products would be a very odd state of affairs; the equilibrium would be different.

Do you understand this sort of thing?

https://en.wikipedia.org/wiki/Chemical_equilibrium

https://en.wikipedia.org/wiki/Anisothermal_plasma

Usually, it is claimed that An Anisothermal plasma has very hot electrons and much "cooler" ions. 

Quote

Examples of anisothermal plasmas can be found among low-pressure plasmas that are excited by high frequency electric fields, see frequency classification of plasmas. They generally exhibit hot electrons that are powered by the alternating electric field, and a neutral and ion component, which is significantly colder due the low efficiency of the energy transfer between light electrons and heavy neutrals and ions.

https://en.wikipedia.org/wiki/Anisothermal_plasma

Quote

In non-equilibrium plasma, the heavy particle temperature is much lower than the electron temperature.

https://www.comsol.com/blogs/thermodynamic-equilibrium-of-plasmas/

However, I'm not sure if 2000-3000 C dissociated water has many free electrons. We need to have much higher temperatures (more than 10.000 C) to ionize water. But dissociated water consists of H+ and OH- ions, mostly. Is there too large difference between H+ and OH- ion temperatures to talk about non-equilibrium plasma?

 

Edited November 20, 2017 by Moreno

[John Cuthber]

A plasma composed of just H+ and OH- ions would be a very weird plasma. 

It's a very long way from any equilibrium.

 

[Moreno]

48 minutes ago, John Cuthber said:

A plasma composed of just H+ and OH- ions would be a very weird plasma. 

It's a very long way from any equilibrium.

 

Why?