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Originally Posted by lyndonashmore
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Originally Posted by papageno
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Originally Posted by lyndonashmore
I think we have covered everything on this point now, so how do free electrons with random thermal motion generate 'density waves?"
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The same way they do it in a metal.
The electrons cannot leave the volume occupied by the plasma.
If they try, a net positive charge arises, and they are pulled back. |
Plasma clouds in IG space are huge. 99.9% of all space? How could an electron 'try to leave it"? |
Is the density uniform?
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Originally Posted by lyndonashmore
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Originally Posted by papageno
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Originally Posted by lyndonashmore
I say it is because the individual electrons perform SHM and there is a phase lag between them so we get the 'density waves'.
What do you say?
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You are wrong.
The electrons do not oscillate about an equilibrium point. They fly around in the plasma.
If they were oscillating about a point, they would be bound to it (like in an atom), and there would not be a plasma.
Do you remember the analogy with sound?
The air molecules have Brownian motion, yet we can have oscillations in the pressure, on length-scales much large than the average distance between the molecules. |
They don't oscillate about 'a point' but their shm is superimposed on their random thermal motion.
You have yet to explain anything. To be honest this is basically hand waving. |
Because hand-waving is enough to show that you do not understand basic physics.
How do the electrons oscillate, if they are zipping around?
What makes them oscillate?
By the way, you still have not shown your full calculations about... anything.
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Originally Posted by lyndonashmore
How, by looking at the individual electrons, do we get density waves in plasma? That is, if you don't agree with 'my' version.
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At length-scales much larger than the average distance between particles, one sees a density of charges, not single charge carriers.
The density is nearly unifrom, because of the relatively high speed and random motion of the electrons.
An electromagnetic wave with a wavelength comparable to these length-scales, does not interact with one electron at a time, but with a high number of electrons at the same time.
We get density waves in plasma, as we can get sound in air.