Fusion Idea: Using Volcano Steam Rings in EM Fields

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Discussion Overview

The discussion revolves around the idea of using the behavior of volcanic steam rings as a model for confining plasma within electromagnetic (EM) fields in fusion reactors like ITER. Participants explore whether a similar rotational motion could stabilize plasma and prevent it from escaping, considering both theoretical and practical implications.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that the EM field in ITER could be configured to make plasma rotate like volcanic steam rings, potentially stabilizing it.
  • Another participant asserts that this method would not work for plasma confinement, emphasizing the existing complex magnetic fields in ITER that already confine plasma ions and electrons.
  • A plasma scientist mentions that rotation of plasma is indeed possible and already implemented in tokamak designs, but warns that specific conditions are necessary to avoid instabilities.
  • Some participants express confusion about the original question, clarifying that the inquiry may not be about external magnetic fields but rather about achieving a self-contained motion similar to smoke rings.
  • There is a discussion about the nature of particle movement in a tokamak, with some participants arguing that particles are not static and follow specific patterns dictated by the magnetic fields.
  • One participant draws a mathematical analogy between vortex rings and tokamaks, suggesting that the principles governing both phenomena may share similarities.
  • Concerns are raised about the stability of rotating plasma, with references to various instabilities that can arise from such motion.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of using steam ring dynamics to confine plasma. While some agree that plasma can be made to rotate, others argue that the mechanisms involved are fundamentally different from those of steam rings. The discussion remains unresolved regarding the applicability of the steam ring model to plasma confinement.

Contextual Notes

Participants highlight the complexity of plasma behavior and the specific conditions required for stable confinement. There are references to various instabilities that can arise in rotating plasma, indicating that the discussion is nuanced and dependent on multiple factors.

Who May Find This Useful

Readers interested in plasma physics, fusion technology, and the dynamics of electromagnetic fields may find this discussion relevant and insightful.

jumpjack
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Looking at these images and video, and thinking about difficulties in holding plasma within EM field, I had an idea:
[PLAIN]http://www.swisseduc.ch/stromboli/etna/etna00/etna0005photo/icons/e71-small.jpg
http://www.swisseduc.ch/stromboli/etna/etna00/etna0005photo-it.html

Video:
http://www.swisseduc.ch/stromboli/etna/etna00/etna0005video2-it.html?id=1
http://www.swisseduc.ch/stromboli/etna/etna00/etna0005video2-it.html?id=5
http://www.swisseduc.ch/stromboli/etna/etna00/etna0005video2-it.html?id=14

Could the ITER e.m. field be configured in such a way it make the plasma "rotate" just like in volcano steam rings (*), thus preventing plasma from escaping?
Volcano rings last some minutes, although steam temperature is around 100°C and environment is below 0°C (etna is 3300 meters tall) and althoug the ring itself looses some steam while moving: both problems would not be present in a closed environment such an ITER.

(*) It's not clearly visible in low-res videos, but the ring persists because the steam it's made of rotates around a "virtual ring", thus stabilizing itself even while the ring is moving up.
 
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no opinions?
 
In short, no. This wouldn't work to confine a plasma.

ITER does have a toroidal geometry. Within the vacuum chamber, there is a complex magnetic field that confines the plasma ions/electrons.
 
Astronuc said:
ITER does have a toroidal geometry.
I know: a "toroid" is the scientific name for... a ring!

Within the vacuum chamber, there is a complex magnetic field that confines the plasma ions/electrons.
I know this too: that's what I'm asking, indeed: can such a magnetic field give plasma ions a rotation like steam particles have in a steam ring? If it was possible, this would (possibly) prevent plasma from escaping from its toroidal shape.
 
Astronuc said:
In short, no. This wouldn't work to confine a plasma.

ITER does have a toroidal geometry. Within the vacuum chamber, there is a complex magnetic field that confines the plasma ions/electrons.

Actually quite the opposite. Not only is it possible, it's already done. I am a plasma scientist and have worked with fusion and tokamak design already has toroidal and poloidal rotation. In fact you can very the spin, as seen in the RFP (reverse field pinch) design. Also the rotation must be very specific or else kink instabilities will for and your plasma will go unstable. If you would like more information I would recommend you look at some of these slide shows

http://w3fusion.ph.utexas.edu/ifs/iiss2010/talks.html

I attended the IISS this year and would suggest you see the slide shows on kink instabilities and on the RFP.

I hope I could be of assistance.
 
Mattenerinfo said:
I hope I could be of assistance.
Thanks, but those document ar far too complex for me... :rolleyes:
 
Keeping it away from tokamak sides is required just for this reason.
 
Mattenerinfo said:
Actually quite the opposite. Not only is it possible, it's already done.

I guess there is a little bit of confusion here. I doubt original question was about using external magnetic fields to confine plasma, rather about using some mechanism similar to the one observed it smoke rings, which seem to be stable without external support. And here I am with Astronuc - it won't work.

But there is also no doubt you are right in tokamak plasma is kept in similar shape - just the mechanism behind is completely different.
 
  • #10
Borek said:
I guess there is a little bit of confusion here.
Maybe due to my poor english, sorry...

What I'd like to know is if E.M. field can be configured in such a way it makes plasma particles move rather than just stay into a toroidal volume. Of course particles are not static in the plasma cloud, but they have (I guess) random movements, like "normal" gas particles inside a balloon. But I know that EM field can impress a movement to a charged particle.
So, could EM be configured in such a way that plasma particles move around the "red circular axis" in this picture?
[URL]http://penolo.com/sketch/r/rrLW.png[/URL]

As far as I can understand from dolphins video above, air particles move both as per blue and red arrows, and I guess red movement is due to blue movement, and both together keep the air confined into the ring (or steam confined in steam ring).
 
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  • #11
Not at all random. Perhaps I am confused on what it is you are asking, but they aren't just confined, in fact the diagram you drew is the exact diagram used to show the particles movements in a tokamak, which ITER is.
 
  • #14
The particles follow the field lines.
 
  • #15
There is actually a mathematical anology between the vortex ring and a tokamak. The vorticity is the curl of the incompressible velocity, like the electric current is the curl of the divergence-free magnetic field. This analogy goes as far as providing analytical solutions that can be used both to describe vortex rings and simple tokamaks (Hill's spherical vortex).

In this sense, therefore the vorticity that is sustained by the uprising air in a volcano, is analogous to the tokamaks magnetic field induced by the coils surrounding the plasma. Just as the ring breaks down some time afer its source of vorticity dies out, a tokamak shuts down when the external magnetic field is shut off.

This analogy aside, you can let the plasma in a tokamak rotate. And actually present day tokamaks rotate at quite a fast rate. There are all sorts of effects this has on stability, some stabilizing, but some also destabilizing. E.g. flow shear instabilities like the Kelvin-Helmholtz instability can actually make the tokamak that rotates less stable.
 

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