Recovery.Gov Project Tracker

[ladajo]

of course wb7 & wb8 beta << 1. It is all about how scaling changes beta.

If scaling changes beta should you have infinitely large reactor for achievement beta=1?
When the talk is about 3 m reactor what value beta should have?
As I heard from Dan Tibets and others: beta=1, B=10T, n=10^22 m^-3 for 3m reactor.

Are there possible anything destroying scaling law?
Like TOKAMAK for which nobody really knows its behavior when instead of induced current non-induced current will flow (so called "Advanced TOKAMAK").

Beta = 1 is the target operating regime. Our best analysis indicates that it should be Beta = to just less than one (blowout control, and other thoughts). Scaling will impact where the balance occurs, and that is part of dialing the knobs on the machine. But in my mind, Beta is somewhat synonimous with Wiffleball.

As far as the WB8 expected outputs, there is a lot we do not know. One of them being the drive potential of the new E-guns on the machine. We know the B field, and we can estimate size from the graphic (from 1.5 to 2.0) based on the bolt patterns and vendor checks. As I recall one estimate was 5/3 size based on the bolt patterns. I would rather go conservative and under-estimate things, that leaves room for pleasant surprise in this case. So say we run numbers for 1.5 x size, 8 x B field (known), and 20KV E-Guns? We can table higher E-gun KV as well if interested.

[Joseph Chikva]

Sounds like it all really makes Polywell a valuable prospect. For the Navy.

As I understand NAVY is interested to get nuke power unit not only for carriers but for much smaller warships as well (cruisers, destroyers, transports, etc.)
But if it really will work that would be valuable not only for NAVY.
And key word here is "if".

[ladajo]

Yes, the elimination or significant reduction of fuels for on ship use is HUGE. It would completely change the way we design and build. It would also save HUGE amounts of resources and money expended now given the HUGE reductions in POL Logistics requirements. Granted, aviation will still burn fuel for the time being, but warships eat LOTS OF GAS.

So, simply put; Yes, Polywell is HUGE for the navy. And that in part is why they are so sensitive about over selling it, in case it does not work. But IF it does, and as such, so far seems to be tracking in that direction, it will COMPLETELY REDEFINE the DOTMPLF Construct for the US Navy that we know and love today. So, unless you are sure it is going to fly, you would need to be very careful about letting the word out. Talk about upsetting the apple cart.

[Joseph Chikva]

So say we run numbers for 1.5 x size, 8 x B field (known), and 20KV E-Guns?

As I understand for WB7:
• size - known
• induction of mag filed - known
• injection energy of electrons - known
• ion number density in the core - unknown
• confinement time - unknown
Yes, beta=1 is a target regime. But definition of beta makes sense if plasma is absolutely stable and its pressure can be expressed by well known Boltzmann equation. And if plasma is not stable? As here I can recall the words of FPGeneration guys where they talk about occurrence of at least two types of instabilities.

[Joseph Chikva]

So, unless you are sure it is going to fly, you would need to be very careful about letting the word out.

I am only saying the true that till now I could not see any hard data after 7-8 generations of device.

[ladajo]

Yes, beta=1 is a target regime. But definition of beta makes sense if plasma is absolutely stable and its pressure can be expressed by well known Boltzmann equation. And if plasma is not stable?

DOes it need to be completely stable or managebly stable? I think in the case of polywell, it will be more manageble. And if so, as long as effiecinecies permit, there should be no reason to not be able to keep the machine operating with a fluctuating Beta. The magnitude of the fluctuations would seem to be the real issue.

I do not think anyone believes that the Polywell plasma is going to be rock stable. But I would argue that it could be stable enough to get the job done. There have been many discussions about maintaining the Wiffleball over long term steady state operations, but until it is tried, we will not know. WB8 is a pulsed machine, just like WB7 and 6. If the scaling laws prove out, and the efficiences are robust enough, there is no reason why a steady state machine could not operate with a fluctuating plasma pressure/B-field. As long as it stays in a band for net power, who cares if it wiggles around? Now, if it is unstable enough that it keeps blowing out the plasma, then that means, that we need to dial things back a bit, and hope there is enough room to keep it at net power levels with a lower Beta (and subsequently weaker wiffleball and electron confinement.)

Just as I can not know if it will ultimately suceed, you can not know that it will ultimately fail. It is all about the trying. "If we knew what we were doing it would not be called research".

[Joseph Chikva]

DOes it need to be completely stable or managebly stable? I think in the case of polywell, it will be more manageble. And if so, as long as effiecinecies permit, there should be no reason to not be able to keep the machine operating with a fluctuating Beta. The magnitude of the fluctuations would seem to be the real issue.

Here I would like to say that beta=1 is like the pool filled to edges.
And if water in the pool is absolutely quiet even one drop will not overflow. But if there the waves appear, the quantity of lost water will depend on intensity of those waves.
Increasing number density you will also increase intensity of instabilities. And I am not sure that dependence will be linear.

In any case I would like to repeat laughable (by TallDave and others) thought that in case if in device instabilities are observed beta=1 is impossible when by definition.

[93143]

of course wb7 & wb8 beta << 1. It is all about how scaling changes beta.

Just to be clear, this is entirely incorrect. Current indications are that all machines at least from WB-6 on achieved beta=1 or very close to it.

WB-6 passed through what appeared to be beta=1 on its way to a discharge condition, and the neutron burst in each test appeared at the same moment as the inferred beta=1 condition. We don't have sufficient data on WB-7 and up to say, but WB-7 at least was intended to replicate the WB-6 results, so one would expect a similar operating regime.

Power scaling is basically entirely B^4R^3 (constant beta), plus of course the effect of drive potential. Loss scaling is more complicated, but it has to do with how various loss mechanisms change with scale, not with any first-order changes in beta.

[Joseph Chikva]

Current indications are that all machines at least from WB-6 on achieved beta=1 or very close to it.

How you would comment the following:

Generally, once beam particles are above ~50 kV, thermalization happens at a rate that causes ion/energy losses which are smaller than the energy production rates due to fusion, unless there are instabilities (such as the 2-stream or Weibel). This is quite a general result.

This is AlexK's post: viewtopic.php?t=3022&postdays=0&postord ... m&start=15
As I understand AlexK is from FPGeneration developing similar to Polywell concept.

Are you still sure that beta=1 is possible?

[Tom Ligon]

EMC2 has underspent these research programs regularly. The only thing I would read into it is that they have been good at estimates and economical with expenditures. A good guess would be they do it deliberately so they wind up looking very good to the Brass, who are slammed with overspent programs on a regular basis. Not shocking, but refreshing.

I dunno that they want to hide so much as only say as little as they can. They haven't turned down interviews so far but rather said there wasn't much to report..

EMC2 is leaving Recovery money on the table if "Final Report Submitted -Yes" means EMC2 is switching to a money source less open to tracking. I can see no other interpretation than someone wants the practical development stage to be a lot more subdued. Could a $200 million demonstration Polywell be kept quiet, even out of the political theatre? Maybe it will be moved to area 51?

Can a Polywell match the volumetric footprint of a fission reactor, could it power a sub? Crew safety would be so much greater, no reactor scrams, etc.

I can't imagine the Navy lolligagging around at this point, and Dr. Park did mention that shortening development time is of great importance...

[tomclarke]

of course wb7 & wb8 beta << 1. It is all about how scaling changes beta.

Just to be clear, this is entirely incorrect. Current indications are that all machines at least from WB-6 on achieved beta=1 or very close to it.

WB-6 passed through what appeared to be beta=1 on its way to a discharge condition, and the neutron burst in each test appeared at the same moment as the inferred beta=1 condition. We don't have sufficient data on WB-7 and up to say, but WB-7 at least was intended to replicate the WB-6 results, so one would expect a similar operating regime.

Power scaling is basically entirely B^4R^3 (constant beta), plus of course the effect of drive potential. Loss scaling is more complicated, but it has to do with how various loss mechanisms change with scale, not with any first-order changes in beta.

Sorry, my comment was total rubbish and is retracted. I was somehow thinking beta->Q and I apologise to all.

[Ivy Matt]

Please provide numbers.
And not common phrases such as "well promising data".

From EMC2 that's all we get so far. I don't expect to see any numbers until they feel they're ready to publish, and I don't expect that to happen for half a year at the earliest, likely a fair bit longer. In the meantime, if we want numbers, we have computer modelers and amateur fusioneers like Mark Suppes. Or someone with enough motivation can try getting the data through a FOIA request. As for me, I'd prefer another interview with Dr. Park.

[TallDave]

Loss scaling is more complicated, but it has to do with how various loss mechanisms change with scale, not with any first-order changes in beta.

I'm starting to wonder how "excellent" confinement plays into that. It seems to suggest that the dominant loss mechanism is still cross-field transport, possibly reduced quite a bit by removing the nubs.

I think Art's last prediction was large ion current into the walls greatly exceeding the (Nebel/Bussard) predicted electron losses. It sounds like that hasn't happened, at least at this scale.

Next step: from .8T to 5-10T! Hope they get the funding.

[TallDave]

EMC2 has underspent these research programs regularly. The only thing I would read into it is that they have been good at estimates and economical with expenditures. A good guess would be they do it deliberately so they wind up looking very good to the Brass, who are slammed with overspent programs on a regular basis. Not shocking, but refreshing.

Amateurs. Real fusion scientists budget $5B and spend $20B.

[Betruger]

EMC2 has underspent these research programs regularly. The only thing I would read into it is that they have been good at estimates and economical with expenditures. A good guess would be they do it deliberately so they wind up looking very good to the Brass, who are slammed with overspent programs on a regular basis. Not shocking, but refreshing.

Amateurs. Real fusion scientists budget $5B and spend $20B.

Seriously. How do they get away with it?