La propulsion à fusion

Socrates a écrit:Voilà qui devrait répondre à quelques-unes de tes questions :
http://focusfusion.org/log/index.php/site/article/the_magnetic_field_effect/

Je connaissais cette page, et j'ai lu aussi d'autres articles de Lerner il y a quelques mois.
Tout celà est très intéressant d'un point de vue physique, justifie plus ample investigation, mais il n'en reste pas moins qu'il ne s'agit que de points chauds de quelques microns cube dans le plasma, et en injectant plusieurs centaines de kilojoules, on récupère tout au plus quelques millijoules par fusion.

Donc, pour l'instant : une expérience de laboratoire intéressante, mais en rien comparable à un système bien plus avancé qu'est le tokamak, et même d'autres dispositifs.

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De toute évidence, Lerner et toi êtes donc en désaccord....
Je ne vais pas relire tout ce que j'ai lu sur la focusfusion et pour essayer de défendre ce qu'il dit,... ça n'aurait aucun sens. Cependant, j'ai le souvenir d'avoir lu ici et là des éléments des répondent à ta question. Il a même dit (lien?) qu'il pense possible d'atteindre un facteur 1000 ... oui, mille fois plus d'énergie de fusion que d'énergie magnétique...
Bien que ce soit en marge de la question que tu poses, je viens de lire ça:
http://focusfusion.org/log/index.php/site/article/university_of_illinois_space_propulsion/
Le plus simple serait que tu vois ça avec lui (et ça m'intéresse)
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Socrates

Il semblerait quand même que Bussard a fait quelques progrès, pour le moins. Voilà ce que j'ai trouvé à ce sujet sur un autre forum, une lettre de Bussard fort intéressante (je préfère la recopier ici plutôt que de donner le lien puisque ce texte est perdu dans la conversation dudit forum) Désolé si je n'ai pas pris la peine de la traduire mais c'est long! Bien sûr la question de la "net enery" par l'IEC est liée à la propulsion spatiale...
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Socrates

Here's a letter Bussard wrote that is basically a condensed version of his google speech, without all the cool photos and history.

Appearantly it's not a Farnsworth derivative, from the final P:
"One final word: Actually our device is really not a variant of Farnwworth/Hirsch, but of Elmore/Tuck/Watson who propeosed the inversion of Farnsworth/Hirsch long ago (ca. 1967). Their problem was the interception of circulating electrons by grids - we removed the grids and replaced them by B field insulated coils - thus our "grids" are the coils themselves."



Dear SirPhilip!:

I have read the threads on the Randi forum, and they are all intent and I am sure well-menaing. However, I have not been able to "log in" on this forum so am writing to you instead. Perhaps you can post this note as a reply and commentary to some of the issues raised by your forum correspondents.

First, what we have achieved in our rather unexpectedly good tests of last November 9 and 10th was an output of DD fusion at about 10 kV, at B fields of 1300 G, in a 30 cm diam device (WB-6) run in a pulsed mode from big capacitors, with a fusion rate of about 1E9 /sec. This works our to be about 100,000 x higher than the data of Hirsch/Farnsworth at similar well depth and drive conditions. The test duration was only about 0.4 masec, but since the electron lifetime is ca 0.1 microsec this is steady-state to the plasma particles. We had neither the money, nor the cooling, nor the power supplies, nor the controls to run this small device steady-state, which is what we need to do, and what requires us to build the full-scale device.

This was a direct result of discovering something during late Spring/ early summer tests of WB-5, which was a closed boc machine, like the early HEPS of 1989. What we discovered was -- in hindsight -- elementary; it was that indeed God is in the details, and the detail of particular importance is that no metal surface penetrated by B fields must occupy more than about 1E-4 to 1E-5 of the total surface available to the recirculating electrons. If this dead fraction is larger, there is NO hope of net power from any such machine. AND, it is essential that the device be recirculating, i.e. that the electrons can circulate out and back through the cusps all over the machine. Of course, this is obvious; but in 15 years no one saw it, not Hirsch, not our consultants not our opponents, not our staff, and not me.

It is consistent with the need for electrons to recirculate about 100,000 times before being lost to collisions with structure, to yield net power.

Please remember that our device has the property that the electron flow and losses are decoupled from the ion flow and fusion generation. Power balance depends on suppresssion of the electron losses, which are derived from the energetic electron injection that forms the gridless negative potential well that traps the ions.

When we figured this thing out, in summer 2005, we quickly designed and quickly built WB-6, using only conformal (with the B fields produced) coil cans, so that no B field uniquely penetrated the cans, and then placed the coils in a special array so that no corners touched (this latter is a long topic having to do with local B fields, and loss of WiffleBall trapping due to line cusp effects at the corners, etc, etc, and is the baisis of our final patents on this thing). It IS the details that make or break the device. And this particular set of details absolutely dominates the performance.

Anyway, we ran the device in October, for beta=one tests, to confirm transport scaling laws, and then in early November to test for fusion output. And, happiness, indeed, three tests on 9 November and one on 10 Novem,ber gave the results mentioned above. The next day, 11 November, we tried it again, but magnet coil motions induced by repeated testing had moved the coils enough that an insulation spot had worn away inside the cans, and the device shorted and blew up one leg, with the full cap discharge. Having no further funding, we had to start shutting doen the lab the following Monday!!! Irony?

As to our funding -- our USN contract still exists, and still has about $ 2M authorized in it. However, year-by-year funding was NOT provide for FY 2006, so that we knew we had to close down early in 2006.. What saved us was Adm Cohen (CNR) who put another 900 K into the program to try to get us down the road to where we DID go, and then we had to quit. It was not a cutoff of OUR funding, but the entire Navy Energy Program was cut to zero in FY 2006, and we were a part of this cut. The funds were clearly needed for the more important War in Iraq.

So, as we cut down, we managed to save the lab equipment, by transfer to SpaceDev, which hired our three best lab people as well, and we are still trying to get the missing $ 2M restored and put into our existing but unfunded contract. IF this happens - which is improhable, given the politics of this election year, and the non-visionary people in Congress - we will redo WB-6 with an improved and better version (WB-7) which should give 5x more output, and run about 50 tests to quiet dissent. AND we will convene a review panel of very high-level and internationally distinguished people to spend about 6 weeks going over this to recommend for or against proceeding sith a full scale demo.

This may or may not happen. If it does, I have little doubt as to the panel recommendation, as the data and insight from WB-5/6 is just too clear. We really have solved the last engineering physics problem that has plagued our work for 12 year s or so. Yes, there is much left to do, iespecially in controls and diagnostics, but these are predictable things not dependent on beating the Paschen curve.

And we still have to develop some reliable e-guns and i-sources, again predictable enginering that costs both time and money, but not new physics.

Why a full-scale demo? Because the system scales oddly: Fusion output goes as the 7th power of the size and Gain goes as the 5th power. Thus there is very little to be gained by building a half-size model; it is too weak to give anything definitive about power production or gain. And our tests were always at about 1/8 to 1/10 scale of the full scale demo. We told the DoD from the beginning that the real program would cost about 150-200 M, since 1987, and they all knew this. However, since the DoD has no charter to do such work, and the political realities were that a big DoD program would attract the ire and power of the DoE to kill it, it was never funded beyond about 1/8 the level required.

So we did what we could and finally DID prove the physics and associated engineering physics constraints, scaling laws, etc, albeit at 1/8-1/10 scale. So what? Doubling the size will not tell us anything we don't already know. The next intelligent and logical step is to build a machine big enough to make net power. And THAT is the same 200 M we have quoted to the DoD since the beginning.

As for energy companies "stampeding" to support us -- It is clear that a view like this is ignorant of the reality of energy companies. There is only one thing the oil cvompanies want, and that is to sell oil, and more oil. So long as the fields pump, the oil companies will squeeze. They have NO, absolutely NO interest in anything new, ins spite of all their foolish ads in magazines for wind mills and solar-PV roofs. It is all just show and tell. I know these guys, and there is no way they would support anything that might get in the way of oil. The only way to stop oil, from their view, is when it does run out. And then they''ll go for deeper drilling, new fields, Gulf geopressure gas, LNG, etc, etc, and keep raising the price, until finally foolish solar and windmills become competitive.

And we are paying the equivalent of $ 500/bbl oil costs. But Exxon and Halliburton are getting richer all the time.

Yes, we would like to build the demo plant, and yes, it will cost about 150 (DD) to 200 M (pB11), and who knows if any investor singly or a group can or will come up with the money. One of the biggest obstacle is the world-wide tokamak lobby, which perpetuates the fraud that Hirsch, Trivelpiece and I foisted on the country in the 1970's when we started the big tokamak ball rolling.

Magnetic confinement fusion is a misnomer, as magnetic fields can NOT confine a plasma, only constrain its motion towards walls. The entire history of the MagConf program has been to reduce transport to neo-classical (not turbulent or instability-driven) losses. And THEN the machines are all inherently and inevitably huge and cost too much and make too much power to ever be economically useful --- as the utilities have been telling the AEC/DoE for 30 years. No matter, the global tokamak program provides jobs for hudreds of thousands of people in many countries, and is a safe place to put political pork funding, simply because it IS NO THREAT TO OIL - it won't ever work, but it sounds good to the untutored public..

As for us; our company still exists, but we will not likely run any demo program - that will be up to others to carry it on, if we all get the chance. Meanwhile, my objective is very simple. I detest the energy stranglehold of our companies on our people, and am going to try to give our idea away at the soonest possible moment. To anyone, anywhere, who might want to undertake its development. And we'll be happy to help in any way we can, if a serious interest develops anywhere in the world.

I think the US, UK, France, et al are lost causes, because of theri commitment to the failed tokamak effort, as is probably Germany, and maybe others, too. China may be a possibility, as it is quite independent even though part of the ITER mess, Russia may be considererd, and countries like Spain, Brazil, Italy, Argentina, and others may logically have an interest.

I believe that the survival of our high-tech civilizations depends on getting off of fossile fuels ASAP, and - if we do not - we will descend into a growing series of "oil wars" and energy confrontations that can lead only to a huge cataclysim. Which CAN be circumvented if only we build the clean fuison machines in time. Our patents are in final form, and I am giving a paper in the Fall, and trying to get a large technical description together for a major paper by summer. We shall see.

One final word: Actually our device is really not a variant of Farnwworth/Hirsch, but of Elmore/Tuck/Watson who propeosed the inversion of Farnsworth/Hirsch long ago (ca. 1967). Their problem was the interception of circulating electrons by grids - we removed the grids and replaced them by B field insulated coils - thus our "grids" are the coils themselves.. And we do know how these work, at last.

Good luck to all of us.

Cheers, RW Bussard

Je réveille un peu ce fil après avoir lu sur sci.space.policy un post qui m'a rappellé de vieux (mais obscurs) souvenirs.
L'auteur évoque la possibilité d'accroitre considérablement la section efficace de la réaction p-11B par une orientation préalable -via une induction magnétique- des spins nucléaires relatifs des noyaux de p et de 11B, ce qui semble coller avec le nombre impair du nombre de nucléons pour les deux noyaux. Mais là mes connaissances en MQ sont un peu trop limitées (ou perdues dans les limbes des années passées). Quelqu'un a-t'il plus d'éléments sur le sujet ?

Henri a écrit:Je réveille un peu ce fil après avoir lu sur sci.space.policy un post qui m'a rappellé de vieux (mais obscurs) souvenirs.
L'auteur évoque la possibilité d'accroitre considérablement la section efficace de la réaction p-11B par une orientation préalable -via une induction magnétique- des spins nucléaires relatifs des noyaux de p et de 11B, ce qui semble coller avec le nombre impair du nombre de nucléons pour les deux noyaux. Mais là mes connaissances en MQ sont un peu trop limitées (ou perdues dans les limbes des années passées). Quelqu'un a-t'il plus d'éléments sur le sujet ?

La section efficace dépend bien du spin et de la parité, et d'une combinaison à l'autre, il peut y avoir des variations de plusieurs ordres de grandeurs. Mais comme dans un mélange d'ions non polarisés il y a déjà des combinaisons favorables, il ne faut pas s'attendre à gagner des ordres de grandeur sur la réactivité moyenne en polarisant tous les ions : dans le cas de D-T, le fait de polariser les réactifs permettrait d'augmenter la réactivité moyenne d'environ 50%, et je ne pense pas qu'on gagne non plus des ordres de grandeur avec p-B11.
Après, encore faut-il que les ions correctement polarisés aient le temps de réagir avant que la polarisation soit perdue du fait des collisions, il y a là aussi toutes sortes de mécanismes de pertes.
Je vais me renseigner un peu plus, il y a quand même moins de littérature disponible pour p-B11 que pour D-T...

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Ce qui m'a fait tilter, c'est que dans le cas de p-B11 les deux noyaux sont de spins k*½ avec k impair, et obéissent donc tous les deux à la même statistique (Fermi-Dirac) contrairement à D-T.

Henri a écrit:Ce qui m'a fait tilter, c'est que dans le cas de p-B11 les deux noyaux sont de spins k*½ avec k impair, et obéissent donc tous les deux à la même statistique (Fermi-Dirac) contrairement à D-T.

Les fermions n'étant pas très grégaires, ce serait plutôt défavorable...

lambda0 a écrit:

Henri a écrit:Ce qui m'a fait tilter, c'est que dans le cas de p-B11 les deux noyaux sont de spins k*½ avec k impair, et obéissent donc tous les deux à la même statistique (Fermi-Dirac) contrairement à D-T.

Les fermions n'étant pas très grégaires, ce serait plutôt défavorable...

Les fermions identiques ! Ce qui n'est pas le cas du proton et du noyau de 11B.

Oui, c'est vrai, cette restriction ne s'applique pas dans ce cas.
Mais de toute façon, vérification faites sur un exemple, même quand elle s'applique, celà ne semble pas être un effet dominant : la courbe de réactivité de la réaction D-D ressemble assez à celle de T-T.

Dans ce commentaire, il y a une allusion suivant laquelle la polarisation ferait gagner un rapport 1.6 dans le cas de p-B11 :
http://www.sciencemag.org/cgi/content/full/281/5375/307a

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:bounce1:
http://focusfusion.org/log/index.php/site/article/more_realistic_plasmoid_simulation_confirms_net_energy_production/
:cadeau: