Fusion with help of accelerators?

[Drakkith]

Another question: if it is assumed that entire plasma focus device is filled with ambient
deuterium gas how they suppose to prevent reactor walls melting through convection and gas heating?

I'd guess that the gas wouldn't be heated high enough to melt the walls. The pinch area is very small, and heat transfer through the walls would keep the small amount of gas inside the chamber cool. Plus, depending on the type of fuel you use, most of the energy may be taken away as neutrons, which wouldn't heat the gas.

 

[Stanley514]

One would have to heat it from all sides equally. It is not easy.

Why?The very idea of fast fusion is to achieve ignition of target with only one ultrashot impulse.In variant with deuterium capsules it is assumed that few lasers compess target from all the sides while one ultrashort laser ignites it.In case with plasma focus there is no need in precompression since plasma coloumn is already dense enough to start some fusion process.

 

[Drakkith]

Why?The very idea of fast fusion is to achieve ignition of target with only one ultrashot impulse.In variant with deuterium capsules it is assumed that few lasers compess target from all the sides while one ultrashort laser ignites it.In case with plasma focus there is no need in precompression since plasma coloumn is already dense enough to start some fusion process.

Ah I see what you're saying. Well, I think the problem isn't that we can't heat it high enough, it's that containment of the plasma at sufficient density is very difficult. I know much of the work involved in practically every fusion device is figuring out how to keep the plasma contained and compressed as well as heated. I don't know the details on laser heating of pre-heated plasma, but I would guess that it's simply an unnecessary complication at this stage. Consider that the containment method of dense plasma focus is the current moving through the plasma itself. Heating the plasma up with a laser may simply be detrimental to the plasma, or at the very least it might do nothing at all if the magnetic field generated by the current simply isn't strong enough to contain the plasma as it's heated. Plus, if I'm reading the info right, there isn't just one spot that the plasma is pinched, it's multiple spots. And these spots are REALLY small. Perhaps too small to effectively heat with a laser. Especially if we can't accurately predict where the pinch will occur at beforehand.

 

[Stanley514]

Heating the plasma up with a laser may simply be detrimental to the plasma, or at the very least it might do nothing at all if the magnetic field generated by the current simply isn't strong enough to contain the plasma as it's heated.

In the best scenario the ultrashort laser pulse would not just heat plasma coloumn,it suppose to cause thermonuclear explosion of the coloumn instantly.If dense focus exist couple of nanosecond it is quite sufficient time for picosecond pulse to explode it.
Picosecond is much smaller piece of time than nanosecond.
http://en.wikipedia.org/wiki/Inertial_confinement_fusion#Fast_ignition

 

[Drakkith]

In the best scenario the ultrashort laser pulse would not just heat plasma coloumn,it suppose to cause thermonuclear explosion of the coloumn instantly.If dense focus exist couple of nanosecond it is quite sufficient time for picosecond pulse to explode it.
Picosecond is much smaller piece of time than nanosecond.
http://en.wikipedia.org/wiki/Inertial_confinement_fusion#Fast_ignition

Interesting. I hadn't read about this development before.

 

[ZapperZ]

In case people missed it, NIF did not achieve ignition last year and missed their stated milestone.

So, are we still trying to achieve fusion with accelerators here? I still find it amusing that people think we can get a net energy out of such a thing. The whole issue with fusion is not just creating the process, but generating energy out of the whole process, i.e. it generates more energy that it uses.

So for people who are proposing this concept of using accelerators, have you ever looked at the wall-plug efficiency of a typical particle accelerator? And what kind of luminosity do you need to actually get more energy than you are consuming? After all, this IS in the "engineering" forum, isn't it? Such issue must be considered and is part of an engineering design concept.

Zz.

 

[Joseph Chikva]

Typical particle accelerator's efficiency is rather high - has 90% order.
Unlike lasers having 1-2 orders lower efficiency.

luminosity?
Ion diods, ion diods with inductive voltage adders give very high currents - tens thousands and even millions amperes in short pulses.
As well as induction linacs.

You can direct two ion beams at the same direction but with different velocities and along the same axis but oppositely you can direct relativistic electron beam with 3 orders of magnitude lower current. As result in some conditions you will get the combined self-focusing beam (high density), in which fast ions will collide slowly moving ions.
Fusion in beams is possible!

 

[Velikovsky]

The general train of thought seems to be "smashing" atoms together to achieve fusion, This is certainly possible but the greatest challenge would be the containment of said fusion. I wonder is it possible to make "compressive clusters" of atoms to achieve fusion around a high gravity core? Such a fusion reactor would be self containing around the core that would in fact act as a "cluster resistor" with the atoms "squeezing" themselves together at the point of highest resistance. Any thoughts or ideas on this? Is it a possibility?

 

[Joseph Chikva]

The general train of thought seems to be "smashing" atoms together to achieve fusion, This is certainly possible but the greatest challenge would be the containment of said fusion. I wonder is it possible to make "compressive clusters" of atoms to achieve fusion around a high gravity core? Such a fusion reactor would be self containing around the core that would in fact act as a "cluster resistor" with the atoms "squeezing" themselves together at the point of highest resistance. Any thoughts or ideas on this? Is it a possibility?

Yes, gravitational confinement is in existence in the stars. But in Earth conditions that is impossible because for starting fusion impracticable large gas quantities of gas have to be combined together.

 

[Stanley514]

You can direct two ion beams at the same direction but with different velocities and along the same axis but oppositely you can direct relativistic electron beam with 3 orders of magnitude lower current. As result in some conditions you will get the combined self-focusing beam (high density), in which fast ions will collide slowly moving ions.
Fusion in beams is possible!

If this is for real why is not used to generate power?Could you give some ref. on such experiments?

 

[Velikovsky]

If this is for real why is not used to generate power?Could you give some ref. on such experiments?

Hi Stanley, I found this link on Ion Beam Fusion at Berkeley National Laboratory, University of California. Very promising work by the look of things!
http://www.lbl.gov/Science-Articles/Archive/sabl/2005/June/01-HIF.html

 

[Drakkith]

If this is for real why is not used to generate power?Could you give some ref. on such experiments?

Because it doesn't generate net power. It uses more than it produces.

 

[Astronuc]

More recent NDCX-II activities

http://hifweb.lbl.gov/public/slides/Friedman NDCX-II for NAS Jan2011+Warp.pdf

http://newscenter.lbl.gov/news-releases/2012/05/08/ndcx-accelerator/

Plasma sources for NDCX-II and heavy ion drivers
http://nonneutral.pppl.gov/pdfpapers2012/Gilson_HIF2012_Sources_Paper.pdf
E. P. Gilson^a, R. C. Davidson^a, P. C. Efthimion^a, I. D. Kaganovich^a, J. W. Kwan^b, S. M. Lidia^b, P. A. Ni^b, P. K. Roy^b, P. A. Seidl^b, W. L. Waldron^b, J. J. Barnard^c, A. Friedman^c
aPrinceton Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, New Jersey, 08543, USA
^bLawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California, 94720, USA
^cLawrence Livermore National Laboratory, P. O Box 808, Livermore, California, 94550, USA