Lawaranceville E-Newsletter

Point out news stories, on the net or in mainstream media, related to polywell fusion.

Moderators: tonybarry, MSimon

Ivy Matt
Posts: 700
Joined: Sat May 01, 2010 6:43 am

Re: Lawaranceville E-Newsletter

Post by Ivy Matt »

Great news! I've been waiting for this moment for years.

Beryllium electrodes - check
Hydrogen-boron fill gas - closer than ever before
Net energy gain - ?
Temperature, density, confinement time: pick any two.

Maui
Posts: 577
Joined: Wed Apr 09, 2008 12:10 am
Location: Madison, WI

Re: Lawaranceville E-Newsletter

Post by Maui »

We’re now over 30 shots and we have tripled fusion yield over last week. Not time yet to break out champagne, as we are still a factor of 4 short of our own record yield of ¼ joule. But going in the right direction. We’ve scanned from low to high fill pressure and we have found the sweet spot for now. Improvements are still needed. For one thing, FF2B was making too much noise when it fired— from shorts or arcs somewhere outside the vacuum chamber. We tracked them down and fixed them. Also, the appearance of the anode continues to evolve from shot to shot. After one shot, a horizontal line appeared on part of the anode, but then disappeared a couple of shots later. For symmetry the anode has to settle down to the same appearance—and thus the same smoothness—everywhere. This will take some time. The image is the raw data from our Far Time of Flight detector(FTF)which shows the arrival of the x-ray peak(small peak at left) and the slower neutrons(big peak at right). Vertical scale is volts and horizontal is time in ns (billionths of a second).From shot 6, June 18. The height of the big peak at right is one way we know we have more fusion yield, as we are now working with deuterium, which produces neutrons from fusion reactions. Another way we measure fusion yield is our silver activation counter and a third way is from our bubble detectors( featured in future posts--stay tuned.)

bennmann
Posts: 233
Joined: Sun May 17, 2009 5:56 pm
Location: Southeast US

Re: Lawaranceville E-Newsletter

Post by bennmann »

https://lppfusion.com/plasma-simulation-advances/

Still my favorite underdog producing plasma - until J Park publishes anything again

Giorgio
Posts: 2830
Joined: Wed Oct 07, 2009 6:15 pm
Location: China, Italy

Re: Lawaranceville E-Newsletter

Post by Giorgio »

Unfortunately it seems that their advancement speed has reduced drastically in the last couple of years.
Not sure if it depends from lack of found or if they hit a stagnant point in their technological development.
A society of dogmas is a dead society.

toddzilla
Posts: 15
Joined: Wed Apr 06, 2011 7:46 pm
Location: North Carolina

Re: Lawaranceville E-Newsletter

Post by toddzilla »

Bennmann, did you notice it was one year to the hour since the previous update in this thread? :D Giorgio, their advancement has slowed, but they're trying harder things and keep having speed bumps. I respect the open manner they discuss advancement as well as challenges.

Ivy Matt
Posts: 700
Joined: Sat May 01, 2010 6:43 am

Re: Lawaranceville E-Newsletter

Post by Ivy Matt »

LPPFusion posted their first reports of 2021 on March 4 and 9 here and here. In sum, work is ongoing on a new set of switches (already arrived) and a new beryllium anode (expected to arrive April 12), with a new round of experiments expected to begin around May 1. If the problems with current oscillation and filament disruption have been solved, leading to an increase in fusion yield, they plan to move on to using hydrogen & boron-11 fuel by the end of summer.

Also, they have a new round of crowdfunding at Wefunder, which opened March 4. Due to changes in SEC regulations the number of investors is now unlimited, so LPPFusion has lowered the minimum investment per investor to one $150 share. They have set a goal of $200,100 for this round, and have already raised over half of that. They are currently limited to a total of $1 million for this round, but after March 15 that limit no longer applies.

In sadder news, LPPFusion CIO Ivy Karamitsos' father passed away from COVID-19.
Temperature, density, confinement time: pick any two.

RERT
Posts: 129
Joined: Mon Jun 02, 2014 9:10 pm

Re: Lawaranceville E-Newsletter

Post by RERT »

It struck me recently that Lpp’s device ought to ignite a DHe3 plasma much more easily than a p11B plasma. The internet seems to think that He3 is cheap enough in small quantities to give that a crack, even if only as a milestone on the way to p11B.

Any thoughts? What have I missed or got wrong?

Skipjack
Posts: 6167
Joined: Sun Sep 28, 2008 2:29 pm

Re: Lawaranceville E-Newsletter

Post by Skipjack »

RERT wrote:
Wed Mar 24, 2021 9:53 am
It struck me recently that Lpp’s device ought to ignite a DHe3 plasma much more easily than a p11B plasma. The internet seems to think that He3 is cheap enough in small quantities to give that a crack, even if only as a milestone on the way to p11B.

Any thoughts? What have I missed or got wrong?
I forget the exact reasoning, but IIRC they think that PB11 is easier than lighter atoms.

Ivy Matt
Posts: 700
Joined: Sat May 01, 2010 6:43 am

Re: Lawaranceville E-Newsletter

Post by Ivy Matt »

I asked a similar question (though not specifically about He3) a long time ago on the Focus Fusion forums. I forget exactly what the answer is, but my understanding of the fuel situation is this: deuterium (what LPP has been using) is useful mainly for diagnostic purposes because it produces neutrons which are measurable. LPPFusion wants to avoid neutrons for a working power plant not just for safety or environmental concerns, but also because the DPF isn't going to get a high enough Q to make sense as a water boiler. They need fairly efficient direct energy capture for their concept to function as a power generator. So any time a neutron is the output of a fusion reaction, that's wasted energy. This means that pure He3 is preferable to any D/He3 mix. But there's a He3 fuel availability problem. B11 is comparatively abundant. The only issue is that the p+B11 reaction is harder to achieve. However, LPPFusion published results nearly a decade ago showing they've obtained the temperatures needed for the p+B11 reaction, so that shouldn't be a big concern. Also, I forget exactly what the mechanism is (perhaps like the metal liner in some other concepts?), but apparently the comparative greater atomic weight of B11 works in its favor in the DPF.
Temperature, density, confinement time: pick any two.

RERT
Posts: 129
Joined: Mon Jun 02, 2014 9:10 pm

Re: Lawaranceville E-Newsletter

Post by RERT »

Hmm.

At temperatures between D-T fusion temps and pB11 fusion temps, DHe3 fusion has a much higher cross-section than either pB11 or DD fusion - in fact an order of magnitude higher than the latter at some points. So a fuel mix even 50/50 DHe3 will have min 20X DHe3 interactions compared to DD at that temp. Also DHe3 is about 5X more energetic than D(D,n)He3. The amount of 'wasted' neutronic power is comparatively low, and if the mix was thrifted on D could be much lower. Also He3(D,p)He4 produces energetic charged paricles, much like pB11, so they could continue to capture energy without raising steam.

Also, with lower Z brehmstralung should be lower, so the plasma would heat up faster, other things equal.

I'm not arguing that DHe3 as a commercial solution is better. There will be at least many 10's of kW of fast neutron power if they fueled their proposed reactor that way, and the cheapness and availability of Boron is a plus.

However, I think testing with DHe3 might produce some eye-catching results.

Ivy Matt
Posts: 700
Joined: Sat May 01, 2010 6:43 am

Re: Lawaranceville E-Newsletter

Post by Ivy Matt »

RERT wrote:
Thu Mar 25, 2021 11:21 am
Also, with lower Z brehmstralung should be lower, so the plasma would heat up faster, other things equal.
That could be a compelling reason to test with D+He3. My understanding is that Bremsstrahlung is supposed to be minimized by the quantum magnetic field effect, but LPPFusion hasn't yet reached the conditions where that effect would apply, so I would say there is a possibility they might want to try out He3 first, or as a backup plan if there are difficulties with H+B11. The main question I have is if it would provide the conditions needed, particularly density. LPPFusion hasn't demonstrated scientific feasibility with deuterium, and I don't think they plan to. Another question is if there are any added difficulties in obtaining He3 or using it in experiments in what is basically a garage laboratory. If there's too much red tape (as there would be with tritium), then it wouldn't be worth using it.
Temperature, density, confinement time: pick any two.

Giorgio
Posts: 2830
Joined: Wed Oct 07, 2009 6:15 pm
Location: China, Italy

Re: Lawaranceville E-Newsletter

Post by Giorgio »

There is no shortage of He3 for experimental purposes at the moment, but there is nowhere enough material to fuel even a demo reactor, so any commercial fusion route out there will need to crack the technological barrier to economically fuse p-B11 or D-T mixtures if we want to see a working technology in our lifetime.

As for LPPF reactor, I spent last few months digging through their papers to understand what are the roadblocks that they hit, so I have had a good refresh of many of the issues that they are exploring in their technological path.
In general Bremsstrahlung control in the LPPF reactor will depend on proving that:

a) the quantum magnetic field effect (Landau quantization) will actually behave according the predicted theoretical model, especially in the part where they predict that the effect is not greatly effected by the atomic numbers (no dependence on fuel type).

b) that the Electrons beam will interact with the plasma (warm it up) according the Hora cross section hypothesis instead of the standard coulomb heating model.
Should the coulomb model prevail, it would prevent any meaningful heating of the plasma as the difference among the two hypothesis is of 4 orders of magnitude.

c) that at the start of compression phase the particles in the plasma filament have enough angular momentum to contrast the inherent instabilities, but too much angular momentum will "fight back" against the compression and reduce yield.
Additionally there are some technical limitations on how to induce this angular momentum that could prevent the machine from ever reaching a sweet spot where all the forces are in balance to give us a net surplus of fusion power.


To sum it up, the LPPF reactor now need to prove that the theoretical model hypothesized in (a) and (b) is real, than they will not need to worry about fuel type (as they can go directly for p-B11).
Once that is proven they will still have to struggle to find a solution to stabilize the plasma filament in the compression phase as for point (c), and that's not going to be an easy task I would say.

Should (a) or (b) not work as theorized, than the whole idea of the LPPF reactor would have to be revised or abandoned, unless they discover something new during the experimental runs.
A society of dogmas is a dead society.

Skipjack
Posts: 6167
Joined: Sun Sep 28, 2008 2:29 pm

Re: Lawaranceville E-Newsletter

Post by Skipjack »

Giorgio wrote:
Fri Mar 26, 2021 7:57 pm
There is no shortage of He3 for experimental purposes at the moment, but there is nowhere enough material to fuel even a demo reactor, so any commercial fusion route out there will need to crack the technological barrier to economically fuse p-B11 or D-T mixtures if we want to see a working technology in our lifetime.
He3 is still a lot cheaper than Tritium right now.
Helion is going to use a D+D -> He3 + D cycle. The T from the second D+D branch will eventually decay into more He3 too. Though I gather that at current market prices it is more economic to just sell the T and buy He3 for a fraction of the price of T.

kurt9
Posts: 567
Joined: Mon Oct 15, 2007 4:14 pm
Location: Portland, Oregon, USA

Re: Lawaranceville E-Newsletter

Post by kurt9 »

One thing I like about Helion's approach is that it neatly does away with schemes like mining the Moon and the outer planets for He3.

Robert Zubrin, call your office.

Skipjack
Posts: 6167
Joined: Sun Sep 28, 2008 2:29 pm

Re: Lawaranceville E-Newsletter

Post by Skipjack »

kurt9 wrote:
Sat Mar 27, 2021 4:50 pm
One thing I like about Helion's approach is that it neatly does away with schemes like mining the Moon and the outer planets for He3.

Robert Zubrin, call your office.
Yeah, the He3 concentration (at least where we checked) on the moon is too low for this to ever be viable and then we have not even talked about the cost of transporting that stuff from the moon to Earth. I mean maybe if SpaceX gets Starship working as well as they hope, then at least the transportation cost is within a viable range (though barely). Still leaves the mining.
IIRC, Jupiter has better He3 concentration, but then you have to deal with an incredibly deep gravity well to get out of. Good luck with that!
I think it is much cheaper to just produce it on Earth. There is a pretty good side market for Tritium to be had as well. I would go with that.

Post Reply