Is there plasma that doesn't radiate visible light? I think the

Varon

Is there plasma that doesn't radiate visible light? I think the electrons falling back to the nucleus radiate visible photons. But what if the plasma only has particles that are not atoms?

rsr_life

Particles that are "not atoms"? Could you give us an example of what you have in mind?

Drakkith

I think he means that the particles in a plasma aren't bound into atoms, so do they radiate light. I believe they will emit various wavelengths of light due to accelerations of electrically charged particles. But i'm not sure.

Varon

Yes.. particles in plasma that aren't bound to atoms... what if they are not charged.. then they won't radiate? Or do all plasma contain charged particles?

Drakkith

You will not have a plasma on earth that isn't made up of charged particles. The only place that could would be inside massive objects such as stars. And even then not really, as a free neutron has a half life of 15 minutes.

Varon

What are examples of plasmas that only contain electrons? Since there is no nucleus to make it fall to lower state, then no photons would be radiated, right? Then this plasma is totally invisible to visible spectrum?

ZapperZ

Er... an atomic transition is NOT the only way to create light. A charge particle being accelerated is another example. What do you think synchrotron light sources are? Or what about free electron lasers? You pass bunches of electrons through something that causes it to wiggle up and down, and viola! You get light!

Zz.

Varon

i see. what plasma sources have both nucleus and electrons in the plasma and what plasma sources have pure ions only? Any site with a list of them?

ZapperZ

Your fluorescent lamps.

The ion beam at RHIC, ion beam milling equipment, etc.. etc.

Zz.

sophiecentaur

I thought that a plasma was defined as having net neutral charge.

ZapperZ

I don't think that's a necessary criteria, is it?

If it is, then asking for "ion beam plasma" would be an oxymoron, which probably won't surprise me.

Zz.

Dotini

Does solar wind radiate visible light? How about a household air ionizer?

Respectfully,
Steve

sophiecentaur

I wouldn't normally just quote Wikkers but they, and a few other more raggedy sites, seem to reckon that a plasma is overall neutrally charged.

It wouldn't be the first oxymoron I'd come across!

Varon

Wiki entry on Plasma stated:

"Definition of a plasma

Plasma is loosely described as an electrically neutral medium of positive and negative particles (i.e. the overall charge of a plasma is roughly zero)."

Is this true?

So overall charge is roughly zero for plasma composed of atoms? And for those composed only of ions.. it's negative charge? Is this correct? So how do each of them (neutral and charged) behave? What is the major (dramatic) difference between them aside from charge?

sophiecentaur

How can you conclude that a plasma can consist of only Ions if you are quoting an article saying a plasma is neutral?

Varon

Zapper mentions about ion plasma beam.. which I assumed is negative charged since it is composed of electrons

sophiecentaur

You are assuming Zapper is correct?