Laser-driven Spherically Convergent Plasma Fusion

This forum is for other possible methods for fusion such as Sonolumenescense, Cold Fusion, CANR/LENR or accelerator fusion. It should contain all theory, discussions and even construction and URLs related to "other than fusor, fusion".
Post Reply
User avatar
Paul W Fontana
Posts: 38
Joined: Fri Mar 13, 2015 7:58 pm
Real name: Paul W. Fontana

Laser-driven Spherically Convergent Plasma Fusion

Post by Paul W Fontana »

A "new" method for producing fusion neutrons has been demonstrated - looks like it's basically a tabletop ICF device: https://physics.aps.org/synopsis-for/10 ... 118.165001.

-- pwf
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Dennis P Brown »

So these Chinese researcher's generated a "billion" neutrons - without knowing the laser energy output or wavelength - a rather useless claim. However, NIF produced many orders of magnitude more neutrons then this current effort and still fell short by five orders of magnitude to reach laser energy break even (forget about ignition.) All in all, a rather pointless method and claim that, until they can at the very least achieve levels of uselessness like that of NIF, really just offer's more bad news. Even a superficial review shows that lining a structure with fuel and exploding it (rather than imploding), will achieve no viable method for real gain - as for a neutron source, again, without parameters of the laser(s), a rather worthless claim.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Richard Hull »

Again, it is putt-putt boat fusion! What is the COP? Rep rate? NIF wants to do it but it is falling on its face.

As already mentioned, any laser fusion process must far exceed the laser energy in physically converted electrical output generation before any discussion of any power delivery scenario can even be discussed. There are always pie-in-the sky ideas and hoped for possibilities, but few of the physicists actually look at the system down the road where the bean counter and engineering realm is forced to face a public only interested in how much it will reduce their power bill!

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Andrew Seltzman
Posts: 815
Joined: Sun Feb 01, 2004 8:02 pm
Real name: Andrew Seltzman
Contact:

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Andrew Seltzman »

From the PRL: "The SGIII-proto laser is a neodymium glass laser operating at triple frequency with the wavelength of 351 nm. It has eight laser beams with four beams on each end, outputting 8 kJ energy at maximum and a pulse duration from 1 to 3 ns."

I have attached a copy of the paper.
Attachments
PhysRevLett.118.zip
(326.89 KiB) Downloaded 579 times
Andrew Seltzman
www.rtftechnologies.org
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Dennis P Brown »

A 8 kJ(!) laser(s) just for a billion neutrons!? What an utter waste of resources.
Andrew Seltzman
Posts: 815
Joined: Sun Feb 01, 2004 8:02 pm
Real name: Andrew Seltzman
Contact:

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Andrew Seltzman »

"maximum deuterium-deuterium (DD) fusion neutron yield of 3.5 × 10^9 with a 6.3 kJ laser."
This is (3.5e9n)/(6.3e3J)=5.5E5 n/J

For a fusor:
The Hirsch 1967 fusor achieved 3e7n/s/kw=3E4 n/J
My best run is 4e6 n/s/kw=4E3 n/J
Andrew Seltzman
www.rtftechnologies.org
User avatar
Paul W Fontana
Posts: 38
Joined: Fri Mar 13, 2015 7:58 pm
Real name: Paul W. Fontana

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Paul W Fontana »

Of course, the stated purpose of the device is not to produce energy, but to generate neutrons. To that end, it appears to me to do a pretty good job. Each pulse produces as many neutrons as about 15 min. of operation of a good fusor. What's not clear to me is whether the hohlraum needs to be replaced with every shot - that would be a major cost and drawback and would presumably be the rate-setting step in an industrial application. Nevertheless, producing 10^9 neutrons in 5e-9 s is pretty impressive!

Andrew - thanks for the efficiency estimate, which shows that the system is no slouch. However, the laser is probably only a few percent efficient (most are), so if you were to include the total energy required per neutron it might come out to the same order of magnitude as your fusor.

-- pwf
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Dennis P Brown »

Yes, the hohlraum has to be replaced (a rather slow process, I bet; also, coating such a pellet takes a good amount of time) - as for efficiency, never really mattered since this was built just to be an extremely low flux neutron source and publish a useless, pointless paper. Considering the capital cost and running such a laser, this really is pointless for such a low yield system (use these neutrons for what?) Also, the size of this setup - I bet that system occupies a rather large laboratory where as a fusor is extremely small in comparison.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Laser-driven Spherically Convergent Plasma Fusion

Post by Richard Hull »

Even with a proposed auto drop, repeating hohlraum setup, what might be a reasonable rep rate? Still, putt-putt boat fusion.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Post Reply

Return to “Other Forms of Fusion - Theory, Construction, Discussion, URLs”