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Varon
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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 said:Particles that are "not atoms"? Could you give us an example of what you have in mind?
Varon said: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?
Varon said: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?
Varon said:i see. what plasma sources have both nucleus and electrons in the plasma
and what plasma sources have pure ions only?
ZapperZ said:Your fluorescent lamps.
The ion beam at RHIC, ion beam milling equipment, etc.. etc.
Zz.
sophiecentaur said:I thought that a plasma was defined as having net neutral charge.
Varon said: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?
ZapperZ said: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.
sophiecentaur said:You are assuming Zapper is correct?
Varon said:Zapper mentions about ion plasma beam.. which I assumed is negative charged since it is composed of electrons
ZapperZ said:Er... "ion beam" is composed of ions, not electrons.
You asked for a "plasma" consisting only of ions, and I gave you an ion beam. This may or may not be a valid example of a "plasma". That's why if a plasma is a net neutral gas, I said that asking for an "ion plasma" is an oxymoron.
Zz.
Varon said:Oh. I thought an electron is an ion. Anyway, wiki says:
"An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative".
Can plasma can be composed of positive or negative ions?
sophiecentaur said:Has anyone mentioned that only positive ions could exist in a plasma because the temperature will mean that passing electrons cannot get captured by an atom. Their energy will be too high.
Varon said:In my earlier message. I asked if plasma can contain ions only (at that time I thought ions are electrons) so I didn't get the answer I seek. So let me ask again, can plasma be composed of electrons only? What if you get a group of electrons and heat them... won't they be plasma?
Drakkith said:Honestly, does it really matter what its CALLED?
sophiecentaur said:Did you not read the definition of a plasma? If you did then did you not get the bit about electrical neutrality? If a plasma is neutral then don't you need both positive and negative charges in there?
How did you intend to get the electrons to all stay together without some positive ions around to stop them drifting off?
Varon said:Ok. I just heard some theorize that dark matter is composed of plasma and wondering what kind of unconvensional particles it may contain that don't react electromagnetically... or too subtle to be detected... they reported about magnetic field that exist right in the middle of nowhere in deep outer space... and wondered if they came from the dark matter plasma..
Drakkith said:Well, remember that like charges repel, so any "plasma" that doesn't consist of equal amounts of charges (ions and electrons) will fling itself apart.
Varon said:Check this out:
http://arxiv.org/abs/0810.5126
Can you try to refute the article?
"We raise the prospect of interesting new plasma effects in dark matter dynamics, which remain to be explored. "
ZapperZ said:This is a meaningless reference. You are using something that is still a "research front" (dark matter) as "evidence".
You shouldn't be trolling such papers when you are having problems with understanding basic physics.
Zz.
Varon said:The reason I started this thread is to understand plasma better in order I can scrutinize the paper myself. So I may share the paper as well.
Anyway. What I learn here is the plasma should always have positive and negative charge. Now that part of the paper makes sense.. that dark matter can only be plasma if there is dark radiation made up of positive and negative charge too. So you guys are helpful in this realization. Thanks.