Plasma Temperature

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
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Squidhat
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Plasma Temperature

Post by Squidhat »

Has anyone actually measured the temperature of D plasma in our tiny vacuum chambers?
It can't be that hot if it can travel down plastic vacuum tubing into a pump. Just a question.
Dustinit
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Re: Plasma Temperature

Post by Dustinit »

Its not really practical to measure the temperature.
An atom at a billion degrees C comes into contact with your theoretical thermocouple
with zero conducted heat loss and with one billion atoms and transfers all its thermal energy to the thermocouple and its temperature rises by one degree.

Same goes for your plastic tubing, the thermal mass and heat transport of the tubing
exceeds the deposited energy several billion times over so you will feel no heat.

Putting a beam onto the plastic is a different matter due to the quantity of particles but will still be orders of magnitude lower in temperature than the particles themselves.

Its more convenient to refer to electron volts than temperature anyway but you can convert one to the other if it makes you feel better.
Just multply Ev by 11604.505 to give the temperature in Kelvin
Ie fusor accelerating voltage 15Kv * 11604.505 = 170 million kelvin
Dustin
Chris Trent
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Re: Plasma Temperature

Post by Chris Trent »

It's been measured in a variety of ways, most commonly by measuring the potential between the grids, which translates directly into the acceleration imparted to the particles crossing between them. (Electron Volts can be translated directly into temperature, Google Boltzman constant or check Wikipedia. http://en.wikipedia.org/wiki/Boltzmann_constant)

I also seem to remember folks having fun measuring with the doppler effect as well.


As far as not melting the plastic, it's simply a matter of density. Despite being incredibly hot, a near vacuum just can't transfer much energy.

Think in terms of an oven. You can open an oven and stick in your hand for a moment without burning it. The air s plenty hot enough, but fortunately for you, the air in the oven doesn't do a terribly good job of transmitting heat so you're fairly safe. I wouldn't try grabbing one of the racks though (Ouch).

Here's some much more in depth reading on the subject:
viewtopic.php?f=14&t=6350#p42810


(Tip, The search function here is your friend. Just about every common question has been covered in an FAQ.)
Dan Tibbets
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Re: Plasma Temperature

Post by Dan Tibbets »

Drifting off topic, but the Alfen waves mentioned in the linked thread... Is this the basis of POPS, Has POPS been demonstrated in an experment, or is it all theoretical? And, is an order of magnitude increase in fusion reasonable (eg- 10 million neutrons per second increased to 100 million neutrons per second)?


Dan Tibbets
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Richard Hull
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Re: Plasma Temperature

Post by Richard Hull »

For our purposes and IECF goals, plasma and plasma heating is bad and undesireable. It is energy wasted, since we are not looking to do classic thermonuclear fusion. Ion temperature is the thing that is important only in that it speaks to fusion ready energy of ion particles in velocity space and not in a plasma.

Talking plasma and its temperature around us is a discussion about unrecoverable losses within the system.

Ideally, (something we will never have), we want no plasma at all, just a stream of high speed deuterons impinging on each other, free of electrons. In our dreams, of course.

Richard Hull

P.S. The term unrecoverable loss is perhaps not strictly true. We could use a heat exchange to capture 100% of plasma losses in theory, but as we tried to convert it to some other, more useful energy, (electricity), then there would be losses in the extreme. Let us say that for the fusor, plasma is a non-productive waste of input energy, for the most part, and why the fusor will never do even moderately significant fusion when compared to its input energy demands. It's a loser just like all the other methods of the past or present........But, it is fun and very easy fusion for the dollar spent. RH
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Chris Trent
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Re: Plasma Temperature

Post by Chris Trent »

Alfen waves are unrelated to POPS.

I haven't taken a look at that in a while, but I seem to recall that POPS was simulation backed by experimental data.

They didn't come anywhere close to order of magnitude differences, but explored a novel theory and new technique. It might lead somewhere else. Who really knows.

Probably ought to start a new thread if you want to continue this.
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