Plasma "Pump"

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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jst
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Plasma "Pump"

Post by jst »

Well Gents: I have a problem. I'm considering the issue of "exhaust" from a fusor. The question is one of how to exhaust the plasma from the fusor, presumable out thru a vacuum system.

Any leads on how to manipulate plasmas? Looking for basic "transport" techniques here.
Roberto Ferrari
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Re: Plasma "Pump"

Post by Roberto Ferrari »

Joe,
Plasma is mostly confined between the grids. As soon as it leaves the ionizing zone you get neutral atoms and molecules.
Then the vacuum pumps takes care of those molecules without problems.
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jst
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Re: Plasma "Pump"

Post by jst »

Fine, but I was more interested in leads to plasma manipulation techniques of the variety that allow transport. I'm thinking that would give a certain degree of control to the vacuum.
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Richard Hull
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Re: Plasma "Pump"

Post by Richard Hull »

plasma is plasma.... and by its very nature you must transport it along 100% energetic lines in a manner that will maintain ionization, thus oozing and loosing energy at a prodigious rate every millimeter of its travel. It is not something that can shoot through a vacuum system or pipes, per se, and arrive at point "B", hot and ready for duty. Stearing it and moving it is easy with electrostatic and magnetic fields but the energy losses are horrific. It is why there is no power fusion to this day.

Richard Hull
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
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Re: Plasma "Pump"

Post by John_Poleto »

What if one was to use a movement feedthough in a vacuum, that would move the inner grid iteslf from point A to B? OF course, then you would have to insulate the grid from the manipulator, and have a wire leading to the grid from a feedthough, and the wire would need to be able to sutain ion bombardment...:-/ But still, would that idea somewhat fit what you were thinking about Joe?
-John
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Re: Plasma "Pump"

Post by Hector »

If you are going to exhaust the plasma from a fusor, then once it leaves the electrostatic confinement well, you will need a magnetic nozzle to transport the electrically charge plasma.

There is a variant of an IEC that can create a plasma jet, but again, once it’s out of the electrostatic well, you need magnetic confinement and that is neither simple nor cheap.

Keep in mind that an IEC plasma is not in thermal equilibrium, but that will quickly change once you send it down a magnetic exhaust.

Hector
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Re: Plasma "Pump"

Post by apollo »

John's way would work, and Richard said that "It must be transported along 100% energized lines" which would include physically moving the grid.
Joe, I think you might be a little confused. You do not want to move the plasma in an IEC type device. If you stop applying power, the plasma will very simply disappear. It is just like an arc (because an arc is a plasma); an arc stops once the transformer's power is shut off. It does not stay there, and it does not need to be moved.
As far as manipulating the vacuum, this is called glow cleaning. You can reach much lower pressures than the base pressure of your pump by glow cleaning. You simply have a relatively low voltage plasma, and try to get it to suck as much current as possible, making a very hot plasma, which will bake the insides of your chamber, removing anything that outgasses. This includes fingerprints, water vapor, etc.
Hope this helps.
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Re: Plasma "Pump"

Post by Andrew Seltzman »

On the vacuum side, what if you were to direct an ion beam emanating from the central grid into the vacuum port of your chamber. That probably would increase vacuum.

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jst
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Re: Plasma "Pump"

Post by jst »

Well, the comments here bring up a few issues. As per Richard, as soon as a plasma leaves a energizing area, it cools to a gas... which is non conductive and can be vented via conventional vacuum technology. This is an option.

As per Liam, Hector, et.al. the problem is seen as an issue of using the energizing features ( and control grids etc. ) to launch the plasma at a vacuum port. But I think Richard's point dictates that the "means of conveyance" must necessarily be energized to maintain the plasma.

The "glow cleaning" tactic is nice, but I'm looking at a more critical issue... namely what do I do with the exhaust from a fusion reaction. Since it will be a high energy plasma, my options appear to be to condense same near a vacuum port, or design some form of "plasma conduit" and probably a variant of a "mass spectrometer" to differentiate fuel from fusion products.

Has anybody ever actually done a "plasma conduit" in anything other than a fluorescent tube?
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Re: Plasma "Pump"

Post by John_Poleto »

Joe,
I think the problem here is that no one quite understands what you want to do. As far as i know, i may be wrong, i don't think there is any exhaust from the fusor itself, as all of the substances in the fusor are contained within the inner grid. Are you suggesting that one would try to propel the plasma from the fusor through the pump, and an attempt to reach lower pressures? If so, this would be nearly impossible, as even a heated gas just below the temperature of plasma would ruin any pump you put it through. Something that you may be relating to is the use of an ion pump, which is very similar to this idea, only without the extremely high temperatures. Hope this helps,
John
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Re: Plasma "Pump"

Post by apollo »

You have confused me a little.
What are you talking about when you say "exhaust"?

"Exhaust" from the fusor is Helium 3 + a neutron or Tritium + a proton (in very small amounts, 50% probability of each)

The entire point of this reaction is to shove all this plasma into a small space, so there is a higher probability of things happening. This is not like an internal combustion engine where the exhaust being fed into the intake manifold will stop the reaction - it actually makes it more efficient as the "exhaust" builds up!

Remember that a fluorescent tube isn't like a water pipe. The plasma doesn't go in an orderly fashion from one end to the other. Plus, where would you put the "exhaust"?

If you're talking about a demo fusor, if you try to move the product of the fusor, it will simply become air/water vapor again. It will simply lose its energy. It's alot like trying to exhaust the molten iron from an iron smelting machine. Once you've removed the heat source, the iron will harden again!

I guess the confusing part is why you would want to get rid of it - and exactly what "it" is.
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Re: Plasma "Pump"

Post by jst »

You Got It. I'm looking to propel/ guide/ pipe the plasma out of the fusor, cool it and vent it out of the vacuum system. Obviously a "condenser" is needed before we arrive at a pump.
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Re: Plasma "Pump"

Post by Richard Hull »

As very, very little fusion is done in any fusor, per unit fuel mass, and as most every fusor is under a flowing D2 regime, more or less, the fusor does have a classic exhaust. The "exhaust" is pretty much D2 ONLY, by mass standards. Next, would be water, nitrogen, oxygen and whatever else is continuously desorbing under the torrent of fusor electrons slamming into the shell. The micro fraction of the exhaust would be hydrogen/tritium but at such a level as to be unmeasurable with an RGA.

The plasma never makes it to the exhaust port on the fusor. It stays pretty much in the center where all the heavy action is. In spite of this, almost the entire energy placed into the fusor and a signifcant portion of the fusion energy winds up at the shell..... (electron bombardment-neutral collisions-gas/heat conduction<minimal>).

The fusor, as normally operated, in the most efficienct manner seen here,...(Rosentiel fusor ~10e7 fusions/second, verified), is pretty much a way to spend money throwing away good electricity at the wall outlet (pennies per hour) and pumping perfectly good, usable, deuterium out into the lab or where ever your roughing pump dumps its load. (much more expensive loss of cash)

Richard Hull
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
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Re: Plasma "Pump"

Post by John_Poleto »

So you are looking to do this in order to reach lower pressures?
jst
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Re: Plasma "Pump"

Post by jst »


John_Poleto wrote:

So you are looking to do this in order to reach lower pressures?



That and greater control of whats actually in the microstar over an extended period. A more precisely controlled environment equates to a more accurate measurement and observation regime.
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Re: Plasma "Pump"

Post by John_Poleto »

Yes, that's all true, but removing matter from the plasma also removes friction and heats required for fusion. If you remove the matter that the plasma is made of, there will be no plamsa.
-John
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