Pb-11 Fusion at CNRS Laboratory in France

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

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quixote
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Re: Pb-11 Fusion at CNRS Laboratory in France

Postby quixote » Tue Oct 08, 2013 10:21 pm

I wonder if this could be used to study direct conversion technologies and techniques while net gain is still being pursued.

Skipjack
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Re: Pb-11 Fusion at CNRS Laboratory in France

Postby Skipjack » Wed Oct 09, 2013 1:36 am

What I love about this is that the NIF has just lost all justification for its existance other than weapons research. Now they cant claim anymore to be anything but an expensive defense project.

Nydoc
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Joined: Sat Nov 01, 2008 9:45 am

Re: Pb-11 Fusion at CNRS Laboratory in France

Postby Nydoc » Wed Oct 09, 2013 4:42 pm

Here is the paper in Nature Communications:

http://www.nature.com/ncomms/2013/13100 ... s3506.html

polyill
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Re: Pb-11 Fusion at CNRS Laboratory in France

Postby polyill » Thu Oct 10, 2013 8:01 pm

The color of this thing is terrific! :)

TheRadicalModerate
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Re: Pb-11 Fusion at CNRS Laboratory in France

Postby TheRadicalModerate » Wed Oct 16, 2013 4:36 pm

This seems to be the money quote:

Moreover, as we are employing the TNSA mechanism to produce the proton pulse, we know that the proton beam is Coulomb-pulled by a relativistic electron pre-pulse cloud. This cloud contains around 10–30% of the pico pulse energy and has an impact on the boron plasma about 100 ps ahead for our geometry: the distance between the thin foil and the boron target was 1.5 mm, which at the velocity of light corresponds to 5 ps travel time. In comparison, a proton of kinetic energy Ep ¼ 1 MeV and velocity (vp/c)2 ¼ 2Ep/(mp c2) will take 21.7 times longer, that is, 108 ps to travel this distance. The relativistic electron cloud may condition the boron plasma just in the proton-target area, pushing out the electrons and forming an ionic channel. The consequence is that the proton pulse energy loss caused by interactions with plasma electrons is reduced, whereas number of interactions with boron atomic nuclei is correspondingly enhanced.


I read this as they're relying on the electron pulse from the proton beam to blow itself and the electrons in the boron plasma out of the path of the proton beam, so the bremsstrahlung losses are substantially reduced. Sound right?

They're estimating 8E7 p-B11 reactions per shot, with each shot using a 400J pulse into the boron and a 20J pulse to generate the relativistic-electron-followed-by-proton beam. 8.7 MeV * 8E7 = 1E-4 J, for a grand total of Q=3E-7. Not exactly setting the world on fire, but interesting.

Note that most of the energy is going into producing the boron plasma off of the solid target, so maybe you can hit the plasma with multiple proton beams. That plasma is is about 200 um wide when the proton beam hits it. They didn't have an exact width of the proton beam but, if I did the arithmetic right, the diameter of the laser spot on the foil that produced the beam is about 1 um. Let's say the beam is 2 um wide when it reaches the plasma, for an area of about 3 square um. Call the usable surface area of the plasma 10,000 square um, and you could possibly hit the plasma with 1000 proton beams, each costing 20J. So now you've got 0.1J output for 400 + 1000*20 = 20,400 J, or Q=5E-6. Assuming you need to get to Q=1000 (hey, optical coupling's still sucks, right?), we're only off by half a billion. Still, what fusion enthusiast is going to let a measly eight orders of magnitude stop him?

Roger
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Location: Metro NY

Re: Pb-11 Fusion at CNRS Laboratory in France

Postby Roger » Sat Dec 14, 2013 8:59 pm

Are the folks @ Emc2 encouraged by these results?
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

marvin57
Posts: 44
Joined: Fri May 13, 2011 2:16 pm

Re: Pb-11 Fusion at CNRS Laboratory in France

Postby marvin57 » Sun Dec 15, 2013 12:32 pm

TheRadicalModerate wrote:I read this as they're relying on the electron pulse from the proton beam to blow itself and the electrons in the boron plasma out of the path of the proton beam, so the bremsstrahlung losses are substantially reduced. Sound right?

They're estimating 8E7 p-B11 reactions per shot, with each shot using a 400J pulse into the boron and a 20J pulse to generate the relativistic-electron-followed-by-proton beam. 8.7 MeV * 8E7 = 1E-4 J, for a grand total of Q=3E-7. Not exactly setting the world on fire, but interesting.

Note that most of the energy is going into producing the boron plasma off of the solid target, so maybe you can hit the plasma with multiple proton beams. That plasma is is about 200 um wide when the proton beam hits it. They didn't have an exact width of the proton beam but, if I did the arithmetic right, the diameter of the laser spot on the foil that produced the beam is about 1 um. Let's say the beam is 2 um wide when it reaches the plasma, for an area of about 3 square um. Call the usable surface area of the plasma 10,000 square um, and you could possibly hit the plasma with 1000 proton beams, each costing 20J. So now you've got 0.1J output for 400 + 1000*20 = 20,400 J, or Q=5E-6. Assuming you need to get to Q=1000 (hey, optical coupling's still sucks, right?), we're only off by half a billion. Still, what fusion enthusiast is going to let a measly eight orders of magnitude stop him?


This proposal seems potentially more efficient to me:

NASA engineer proposes new type of fusion thruster for space travel

A Fusion Thruster for Space Travel

Chapman’s idea is to use an off-the-shelf laser to shoot at a double-layer target. The first would be comprised of a “thick” sheet of metal foil, which would respond to the laser shots by accelerating the protons. The ensuing out-rush of electrons would leave behind an increased positive charge, which would wind up creating an unbalance between the protons left behind, resulting in a small explosion, which in turn would speed up the protons hurtling towards the second layer, a thin slice of boron-11.


Presumably we wouldn't HAVE to use it in space or for thrust, it seems to me to be a reasonable candidate for power generation via direct conversion as well.


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