Recovery.Gov Project Tracker

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

Moderators: tonybarry, MSimon

rcain
Posts: 992
Joined: Mon Apr 14, 2008 2:43 pm
Contact:

Post by rcain »

ScottL wrote:... where as there is no such claim from the polywell project.
yes. that is a good point. and probably for the best at this stage in the game.

but i want more. so much more. so do we all, i dare say.

(continues wait-state-on-interrupt).

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Post by ladajo »

rcain wrote:guys, well done on the watch. without this thread we would be totally in the dark... rather than being... totally in the dark.

just wondered what level of 'confidence' we might put on such claims as:
ScottL wrote:...Not sure what you're expecting or your definition of success, but what I do expect from a final report on WB8 is that so far the data substantiates the scaling theory....
- do we seriously expect any such technical announcement/public report?

and
ladajo wrote:... As, by definition, it {WB 8.0} means that DD worked, and worked well enough to take a crack at PB&J. {WB8.1}...
- do we have a definitive fact/paper trial for this deduction?

if so, i think it very newsworthy.
That is what the contract says. 8.1 is contigent on 8.0 working well enough. It could not be clearer.
If they enact the 8.1 clause, that is a clear statement that 8.0 was good enough.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

rcain
Posts: 992
Joined: Mon Apr 14, 2008 2:43 pm
Contact:

Post by rcain »

ladajo wrote:...That is what the contract says. 8.1 is contigent on 8.0 working well enough. It could not be clearer.
If they enact the 8.1 clause, that is a clear statement that 8.0 was good enough.
and how 'well' do we know that DD was successfully performed on 8.0?

(might there have been other reasons to progress - eg: to test DD on 8.1 instead?)

- ps. sorry, that seems a bit of a stupid question, having written it. but i'll leave it there anyway, since it still means something.

we 'assume' they have been using DD pretty much throughout 8.0 (though they could be using other gasses i suppose). for the neutrons, n'shit.

perhaps what to meant to say was - i suppose the newsworthy items are:

- 'moved on to pB11 testing' (which we have as a stated contractual aim irrc.), - which is kool in itself.

and

- 'we moved onto pB11 having achieved Q of X?' using DD/DT - and we are supposing that figure X is 'impressive' wrt what has been achieved elsewhere (eg: by JET).

lastly:

- 'the scalng law is proven to be as expected' furthermore practical/tractable. from our pov. this remains an 'assumption/deduction as well i believe.

godammnit. i hate all this secrecy.

can't you pull a few strings Ladajo? lift the Official Secrets Act (whatever you have over there)?

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Post by ladajo »

We still do not have indicatino that they have enacted the 8.1 clause. We should see it via the money trail.

If they enact the 8.1 clause it means, by contractual defiinition, that DD (8.0) was good enough to suppose PB&J (8.1) is feasible to test for.

Remember that the explicit purpose of 8.0 is to test DD. The explicit purpose of 8.1 is to test PB&J.

The system is not set up to hide the money. It will be the tell.
If anyone is concerned, they can FOIA about the money and contractual activation of the 8.1 phase. But that is not really necessary, as the money part is already visible via several public access mechanisms. The easiest of which to use is FPDS.gov.

It is anyone's guess in public as to when/if they think the team will move on the the 8.1 phase. And in fact, they may not. They may determine that DD is ok, but not good enough to take the shot at B11. That would really suck, as then it would be more wait and see, as 8.1 does not activate, and they run the curve out on the 8.0 contract. And the public woul dnot know if 8.0 was a bust or viable, but just not viable enough to justify 8.1.

Follow the money as we like to say.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

rcain
Posts: 992
Joined: Mon Apr 14, 2008 2:43 pm
Contact:

Post by rcain »

ladajo wrote:...Follow the money as we like to say.
hmm.thx.

keep a look out over the next month or two then. i'm supposing there'll be another round of reviews etc before any decisions.

rcain
Posts: 992
Joined: Mon Apr 14, 2008 2:43 pm
Contact:

Post by rcain »

ps. i'm supposing there's such a thing as 'fast-tracking' in the US Navy - for particularly promising/well-performing projects. no sign of any of that happening for our dear Polywell i suppose?

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Post by ladajo »

The last money movement was the aforementioned pre-summer expeditiure of the $1.2 mil. I would expect to see a post summer sum any time. As for 8.0 completion, other than the contractual date posted, the wrap up is anyone's guess. And, obviously, dependant on how things are going, ONR could change the date targets again...
They have a decent amount of funds, and some more time, so if the funds burn rate goes lower 9think Kit bought, testing continues, less or no captital expenditures), they can always extend dates if need be, and not have to obligate more funds.

I am happy and encouraged to some degree with every day that goes by and we don't see the "we are done, insurmountable road block encountered" message.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Post by ladajo »

ladajo wrote:
ladajo wrote:I poked around on my laptop and have not found the file.
I am thinking it is back in the office via the desktop.

Once back in the land of "no goats on the bus" next week, I will pull it up and see what numbers I churned.
Dan,
Well, I am back in the land of spoiled teenagers, but go figure, went right out the door again. A couple of days visiting one of my favorite places (Lincoln Labs) and then will finally get back to homebase to look for my napkin math.

I have not forgotten. Not that you probably care anymore...
Dan,
I looked at my napkin math, and then remembered this:

viewtopic.php?p=81901
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

MSimon
Posts: 14334
Joined: Mon Jul 16, 2007 7:37 pm
Location: Rockford, Illinois
Contact:

Post by MSimon »

We still do not have indicatino that they have enacted the 8.1 clause. We should see it via the money trail.
Are indicatinos like neutrinos? The barely leave a trace.
Engineering is the art of making what you want from what you can get at a profit.

alexjrgreen
Posts: 815
Joined: Thu Nov 13, 2008 4:03 pm
Location: UK

Post by alexjrgreen »

Nah, they knocked a "y" off...
Ars artis est celare artem.

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Post by ladajo »

MSimon wrote:
We still do not have indicatino that they have enacted the 8.1 clause. We should see it via the money trail.
Are indicatinos like neutrinos? The barely leave a trace.
:D
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Post by D Tibbets »

Looking at two versions of the fusion cross section curves near the bottom of this link shows that the D-T reaction rate is near the D-D reaction rate at ~ 1 MeV. The D-He3 reaction rate is the leader at this temperature range (~0.8 to 1 MeV), so if there is any further fusion with the D-D products it is probably D-He3.

http://thepolywellblog.blogspot.com/201 ... works.html

That is only considering the fusion cross section contribution.

The likelihood of fusion is also dependent on the duration of the isotopes' lifetime within the system. For deuterium isotopes introduced at low energy there is electrostatic confinement from the potential well. Numbers of > 100,000 -passes have been mentioned in WB6, and Bussard stated that at least 10,000 passes were required for significant fusion (eg: perhaps ~10% fuel burn up or even less). Nebel mentioned that the alphas from P-b11 fusion at ~ 3 MeV only bounce around ~ 1000 times before escape through a cusp. This is a simple estimate based on the cusp escape surface area verses the total surface area of the Wiffleball. The speed is such that the potential well can not contain the particle,thus there is no electrostatic confinement. The produced tritium at ~ 1 MeV and the He3 at ~ 0.8 MeV will behave in a similar way (~ 1000 passes before escape).

If the system was an ignition machine, IE: the fusion products heat the plasma, the picture would be different. But at ~ 1 MeV the Coulomb collision cross section is ~ 100 times less than the collision crossectio0n of the deuterium plasma (with a potential well of ~ 80 KeV) The Coulomb cross section falls at the ~1.75 power of the temperature, so for a ~ 10 fold increase in temperature the Coulomb collision cross section falls ~ 60X. This is important for the machine operation on several levels. And this relative low confinement time and Coulomb collision cross section is why the plasma is not significantly heated by these fusion products. It is far different in an ignition machine (like a Tokamak), basically because the fusion products lifetime within the reaction plasma is many thousands of times longer and that dominates the cross section considerations.

For the fusion produced tritium and He3, comparing the residence time in passes, results in ratios of ~ 1000/ 100,000 times (or More). This directly correlates to ~ 1/100th fusion rate compared to D-D fusion rates for the tritium, and upwards of ~ 1/10th for He3.

So, some secondary fusion may occur but at rates of only 1-10% of the D-D fusion numbers (in this very forgiving analysis). The contribution to the final yield is miner, and the rest of the tritium leaves the system intact. Contrast capturing, processing and reintroducing the tritium at low energy. Now it is trapped by the potential well, and with it's high fusion cross section it will quickly burn with the deuterium at the potential well depths of ~ 80 KV/ 80 KeV. As the D-T reaction gives ~ 19 MeV of energy, the contribution may actually be nearly equal to the overall D-D fusion yield.

I suppose the He3 would not be reintroduced to the D-D reactor as it may have too much value , for instance powering a dedicated aneutronic D-He3 reactor.

Bussard discussed the reuse of the tritium and He3 products to boost the yield of a D-D reactor, along with a blanket of B10 to squeeze out the maximum amount of energy, without significantly increasing the input energy costs. The penalty would be handling the high energy neutrons from the D-T reaction. That could effect shielding, system life cycle costs, etc. Taking the tract of the Tokamaks, a portion of the 17 MeV neutrons from these secondary tritium reactions could be used to breed even more tritium, thus incrementally increasing the tritium contribution to the final energy balance. This opens up the possibility of making a marginal D-D system an economical solution.

Dan Tibbets
To error is human... and I'm very human.

hanelyp
Posts: 2261
Joined: Fri Oct 26, 2007 8:50 pm

Post by hanelyp »

Don't radiation losses from the plasma scale something like T^4? Meaning a 1MeV plasma radiates photons at 10,000 times the rate of a 100keV plasma. From the graph, the D-D cross section at 1Mev is a bit less than 10 times the section at 10keV, clearly favoring the lower energy over the latter for fusion gain with that fuel.

D Tibbets
Posts: 2775
Joined: Thu Jun 26, 2008 6:52 am

Post by D Tibbets »

No, Bremssthrulung radiation losses scale as ~ 1.75 power of the temperature. So an increase from 100 to 1000KeV would result in radiation losses ~ 60 times higher. I believe the Bremssthrulung radiation losses dominate over the black body and cyclotron radiation losses. The 60 fold increase in Bremstrulung losses in this example far out weighs the modest D-D fusion rate increase in this range. This is one reason why I believe Bussard chose ~ 80 KV for an operating D-D Polywell. It takes advantage of the steeper portion of the fusion cross section slope, while having a lower Coulomb collision cross section (higher MFP) and avoiding much of the increasingly painful Bremssthrulung losses. From ~ 10 to 100 KeV the D-D fusion cross section increases ~ 100 fold, further gains up to ~ 1 MeV only increases the rate by ~ 3-5 X.

Note that the Z=5 for boron increases the Bremsstrulung losses by a factor of ~ 25, or rather ~ 13 when the proton contribution is considered .
(25 +1) /2= 13X. Diluting with a 10 fold excess of protons results in (25 + 10)/11 = ~3. This significantly decreases the Bremssthrulung losses at the same final density. I'm unsure how it effects the fusion rate. I'm thinking the penalty is not much.

Dan Tibbets
To error is human... and I'm very human.

ladajo
Posts: 6258
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Post by ladajo »

Dan,
Nebel talked a couple of times about knob options to control Bremstrahlung. One of the leading of which was fuel mix/density.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

Post Reply