Learning Resources

Discuss how polywell fusion works; share theoretical questions and answers.

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BenTC
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Learning Resources

Post by BenTC »

Bumped into this book The Physcis of Plasmas by Richard Fitzpatrick, University of Texas at Austin. I can't judge its worth, but from a novice point of view looks reasonably extensive at 261 pages. Can anyone more knowledgable identify any particular bits that might be of particular interest for a Polywell.
In theory there is no difference between theory and practice, but in practice there is.

Solo
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Post by Solo »

I hear that Chen is the most widely used introductory text to plasma physics. It's only about 60quid on ebay used, not too bad.

chrismb
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Post by chrismb »

Remember that Polywell isn't designed to run a plasma, it requires electrostatic fields. So this text would mislead most initiates in the Polywell.

Whether it will form a 'suitable' plasma environment arising from thermalisation, as Art envisions or that Rick hopes as a fall-back position, it still confuses the magnetic confinement of a plasma, in a quasi-spherical magnetic field, with the radial electric field intended as the ion-accelerating means.

It is a tall order to believe a device can BOTH electrostatically accelerate an 'ion' plasma and also magnetically confine an 'electron' plasma in the same volume; the very point, in fact, that has lead to the Polywell's last patent application being given a [non-final] rejection.

Solo
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Post by Solo »

Chrismb: what the heck are you talking about, of course it's a plasma! I really think quite the opposite: most folks here don't know enough basic plasma physics, myself included. In particular, to only learn the Polywell version of the story is a lopsided introduction to the subject.

MSimon
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Post by MSimon »

chrismb wrote:Remember that Polywell isn't designed to run a plasma, it requires electrostatic fields. So this text would mislead most initiates in the Polywell.

Whether it will form a 'suitable' plasma environment arising from thermalisation, as Art envisions or that Rick hopes as a fall-back position, it still confuses the magnetic confinement of a plasma, in a quasi-spherical magnetic field, with the radial electric field intended as the ion-accelerating means.

It is a tall order to believe a device can BOTH electrostatically accelerate an 'ion' plasma and also magnetically confine an 'electron' plasma in the same volume; the very point, in fact, that has lead to the Polywell's last patent application being given a [non-final] rejection.
My understanding of the patent rejection is that there are non-novel claims.

Why not magnetic confinement and electrostatic acceleration? I presume you have heard of magnetron tubes.
Engineering is the art of making what you want from what you can get at a profit.

chrismb
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Post by chrismb »

Solo wrote:Chrismb: what the heck are you talking about, of course it's a plasma!
What are the conditions of the expected plasma, then - let's check what you think the density, temperature and Debye length are, first off....

chrismb
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Post by chrismb »

MSimon wrote: My understanding of the patent rejection is that there are non-novel claims.

Why not magnetic confinement and electrostatic acceleration? I presume you have heard of magnetron tubes.
I do not dispute it is possible. I would dispute it is likely.

The rejection is a divisional matter - as I understand it, the examiner doesn't see any particular reason to believe it can be both a means to accelerate ions and also to confine. This is in no way means it is impossible, but is merely that there isn't sufficient evidential material to support the claim.

Magnetrons work with electrons, not ions or plasmas. Surely the comparison is with a thyratron - everything seems fine whilst nothing much is happening then, wham, an electrical discharge cascades across the volume and creates an electrically conductive (i.e. cannot hold up an electric field) plasma.

MSimon
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Post by MSimon »

chris,

Other than the mass difference why should ions vs electrons matter?

Some times you seem so perceptive and other times you seem thicker than a brick. It is like two different people using your name.
Engineering is the art of making what you want from what you can get at a profit.

chrismb
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Post by chrismb »

MSimon wrote:chris,

Other than the mass difference why should ions vs electrons matter?

Some times you seem so perceptive and other times you seem thicker than a brick. It is like two different people using your name.
The difference isn;t the issue, the mix is. Magentrons have no ions in them, just a load of space-charge inducing electrons. This is something quite different to a thyratron with a 'quasi-neutral' mix of ions and electrons undergoing a discharge event.

MSimon
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Post by MSimon »

chrismb wrote:
MSimon wrote:chris,

Other than the mass difference why should ions vs electrons matter?

Some times you seem so perceptive and other times you seem thicker than a brick. It is like two different people using your name.
The difference isn;t the issue, the mix is. Magentrons have no ions in them, just a load of space-charge inducing electrons. This is something quite different to a thyratron with a 'quasi-neutral' mix of ions and electrons undergoing a discharge event.
But is it a "real" discharge event? The current is limited by well formation.

And well formation says that there may be a series of layers of alternating separated charges.

Of course with no data to go on you could be right. OTOH we have the Navy puttying up significant money so the odds are that something so fundamental is not a problem.
Engineering is the art of making what you want from what you can get at a profit.

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