An idea to prevent thermalization??

[JoeOh]

I hope this is the appropriate subtopic to put this question in.

Just a few days ago I came across the Polywell fusion design and I am amazed by it's simplicity and it's potential. I've seen all 8 clips Tom Ligons interview on YouTube so I get the theory of operation and current problems to be solved.

One of the main issues with the Polywell I read about is the eventual thermalization of the electron cloud.

I have an idea on how to combat this. But I'm not sure that I'm the first to think of it. I tried to search on this site and others to no avail.

The idea is to get the electron cloud to the density it needs to be so that it will act diamagneticly against the magnetism of the field coils.

Next step is to rapidly increase and decrease the magnetic fields many times per second to "squeeze and loosen" the electron cloud.

This may keep the electrons from "slowing down" too much. I figure this will keep the electrons in the cloud continually jumbling along if the electron density is high enough. Kind of like inducing friction among the particles.

I might be crazy here, but I think this would be a great way to control the energy levels within the cloud with predictable results as well as tamp down the effects of the x-ray "braking radiation" phenomenon if P+B11 reaction is used.

If I'm misguided on this then that's ok, but is this a sensible idea? Has someone else suggested this before? Thanks.

Joe-

[D Tibbets]

I don't understand about the effects of varying conditions rapidly and effecting the behavior of the plasma. There is POPS theory that R. Nebel worked on before he joined EMC2. I understand this uses microwave energy to selectively heat ions and/ or electrons (?) causing waves or bunching of the particals. In traditional wire gridded fusors this can evidently increase performance, perhaps by a large amount. Also, the drive voltage on the magnetic coils or ion/ electron guns might be varied rapidly.
Rapid variation of the magnetic field might be done with copper wire magnets, but if the magnets are superconducting, varying the strength would defeat at least some of the energy storage advantages of the superconductors. Perhaps a constant magnetic strength could be maintained with he superconductors, and supplimental copper windings might be used to introduce relatively small and rapid changes in the magnetic field strength.

Dan Tibbets

[Nik]

Uh, probably not applicable here but, IIRC, there was something from 'mainstream' fusion research about 'gently' modulating plasma more frequently than instabilities grow to prevent those developing...

Adding 'tweaker' copper coils to a Polywell's steady-state superconductor network could make sense...

( And if result is HV modulation, perhaps there would be side benefits...

[JoeOh]

Yea, I figured my idea was a little too simplistic. And I didn't think about taking into account the difference between copper coils and superconducting coils.

But if you has SC coils and supplemental copper "pusher" coils and the electron density was enough, it should keep the cloud continually jumbled.

But is there any particular reason why this idea won't work? I understand that plasma and regular-gas are different because of the energy levels, but if the plasma is dense enough it should act similar to regular non-ionized gases.

But then again I'm just a "weekend-scientist".

[MSimon]

I don't understand about the effects of varying conditions rapidly and effecting the behavior of the plasma. There is POPS theory that R. Nebel worked on before he joined EMC2. I understand this uses microwave energy to selectively heat ions and/ or electrons (?) causing waves or bunching of the particals. In traditional wire gridded fusors this can evidently increase performance, perhaps by a large amount. Also, the drive voltage on the magnetic coils or ion/ electron guns might be varied rapidly.
Rapid variation of the magnetic field might be done with copper wire magnets, but if the magnets are superconducting, varying the strength would defeat at least some of the energy storage advantages of the superconductors. Perhaps a constant magnetic strength could be maintained with he superconductors, and supplimental copper windings might be used to introduce relatively small and rapid changes in the magnetic field strength.

Dan Tibbets

For ions and a reasonable size device .1 m to 3 m the frequencies run from LF (100 KHz) to HF (30 MHz). For electrons the frequencies are in the 500 MHz region (depending on device size).

[MSimon]

Yea, I figured my idea was a little too simplistic. And I didn't think about taking into account the difference between copper coils and superconducting coils.

But if you has SC coils and supplemental copper "pusher" coils and the electron density was enough, it should keep the cloud continually jumbled.

But is there any particular reason why this idea won't work? I understand that plasma and regular-gas are different because of the energy levels, but if the plasma is dense enough it should act similar to regular non-ionized gases.

But then again I'm just a "weekend-scientist". ;)

If plasma acted like a gas it would be a LOT easier.

[JoeOh]

Supplemental copper coils pulsing at 500Mhz? We can do that, what the hell are we waiting for, lets do this thing!!

Oh yea.....the funding

[MSimon]

Supplemental copper coils pulsing at 500Mhz? We can do that, what the hell are we waiting for, lets do this thing!!

Oh yea.....the funding :(

They better be small coils. Less than .1 wavelength preferred.

[JoeOh]

Wow, .1 (or less) wavelength is tiny. Yea, I guess a microwave generator would do the trick. Now it's just a matter of tuning it to 500MHZ and how much power it needs to put out so the electron cloud stays "hot", but not TOO hot.

How much power do you think will be needed in watts to do this?

[D Tibbets]

It occurs to me that inputting microwave energies might (?) preferentially heat electrons at a given energy. Would this allow for preferentially heating the electrons that are spreading into the cold side of the thermalization curve? This would compliment the method of removing the hot electrons (they leave through the cusps faster by both increased speed within the wiffleball-(shorter time to reach the ~10,000 pass average before they hit a cusp, and by being less likely to recircuate as thay exceed the recirculation/ drive magrid voltage.
This is the first time I have appreciated a 'knob' that might (?) selectively impead electron thermalization on the low side of the curve.

I've wondered how many of the low energy electrons would ossilate on magnetic fieldlines without reaching high enough in the cusps to exit the magrid and thereby be reaccelerated back towards the center. I'm assuming the increasing magnetic field strength in the cusps (between compressed/ and thus stronger fields) could reverse/ bounce the low energy electron back, despite the excess electrons inside pushig outward (perhaps modified by debye conciderations. Is this possible?

Dan Tibbets

[chrismb]

This thread, and also a comment in another thread, makes me think "errr... have I missed someting??..."

As far as I understood it, electrons were generally expected to thermalise but that they would be of a low energy?

Much as I argue that ions will thermalise, I'll at least agree there is a viable discourse there to hold on that subject. However, I have not begun to contemplate that electrons might not thermalise. That seems to me to be "beyond inevitable"!