Fusion with help of accelerators?

  • Thread starter Stanley514
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In summary: However, in practice, we often need to add an external energy supply in order to maintain the plasma and keep it from becoming stable.In summary, the experiment failed because they couldn't get the neutrons from fusion. They suggest using neutral beams to achieve fusion, but it is not feasible because of space-charge problems.
  • #36
Stanley514 said:
What is principal difference between inertial fusion and accelerator/plasma focus fusion?
Why you cannot easily achieve conditions in former similar to the first?
Could you create some local thermonuclear explosions with beam fusion?

I'm not sure this can be explained if you don't already know the basics of nuclear fusion power.
 
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  • #37
Drakkith said:
I'm not sure this can be explained if you don't already know the basics of nuclear fusion power.

I conceptually understand how laser-driven ICF works, basically imparting a massive amount of energy into a small object which causes the object to heat up and implode. How does magnetic confinement work, though? From my understanding, a tokamak's magnetic fields confine the plasma which is at a (very) high temperature. But what gives the plasma its high temperature?
 
  • #38
cdotter said:
I conceptually understand how laser-driven ICF works, basically imparting a massive amount of energy into a small object which causes the object to heat up and implode. How does magnetic confinement work, though? From my understanding, a tokamak's magnetic fields confine the plasma which is at a (very) high temperature. But what gives the plasma its high temperature?

Here you go: http://en.wikipedia.org/wiki/Tokamak#Plasma_heating
 
  • #39
mheslep said:
The problem is a 'bounce' off collision is much more likely than a fusion event, regardless of density, so that beam-beam attempts inevitably waste more energy than they can generate.

I wonder if it is possible to form beams right form and in the plasma. Some MHD pumps, maybe? I don't really know the available 'tools' for this, but if it's possible then we won't waste the energy of the beam: it would just heat up the plasma which we are working from.
 
  • #40
Rive said:
I wonder if it is possible to form beams right form and in the plasma. Some MHD pumps, maybe? I don't really know the available 'tools' for this, but if it's possible then we won't waste the energy of the beam: it would just heat up the plasma which we are working from.

I'd guess it's about as likely to happen as pumping multiple "beams" of water at supersonic speeds in my swimming pool.
 
  • #41
Drakkith said:
I'd guess it's about as likely to happen as pumping multiple "beams" of water at supersonic speeds in my swimming pool.

Well... On small scale and for water it's on the edge but more or less possible... Cavitation? Steady (longitudial) waves?
 
  • #42
Rive said:
Well... On small scale and for water it's on the edge but more or less possible... Cavitation? Steady (longitudial) waves?

The problem is how you would create these beams inside the plasma AND keep the other plasma away from plasma in the beams. The hotter you heat the plasma outside the beams, the harder it is to contain.
 
  • #43
Another inertial confinement scheme involves using tabletop lasers to accelerate ions from a solid target into another target of D-T fuel. If you shoot an ultra intense laser pulse at a thin solid target, you can accelerate ions from the rear-side of the target via a process called Target Normal Sheath Acceleration. The laser pulse immediately ionizes the target into plasma. As the laser pulse propagates through the target, electromagnetic fields from the laser pulse drive electrons toward the back of the target which then form a sheath. The resulting charge segregation region between the electron sheath and the rest of the target set up a strong electric field which accelerates the ions.

If this target happens to contain, say some deuteron atoms, then you'll get MeV-KeV deuterons traveling toward the D-T fuel. They will then proceed to conveniently fuse with deuterons in the fuel. DD Fusion!
 
  • #44
Yes but like Beam-Beam fusion, the reactions are much too sparse compared to scattering events.
 
  • #45
What is progress with fast ignition approach in which fuel is compressed with light ion beams and ignited with picosecond laser?Is it far from a positive net gain?
 
  • #46
The parameters for the ion beam have been met in individual experiments but not in the same experiment as far as I know.

The Sandia website has some good information regarding progress on the topic.
 
  • #47
Is it possible to combine dense plasma focus and fast ignition approaches?
They claim that plasma focus is very dense.If so, it could be easily ignited with
picosecond laser and thermonuclear explosion should happen?
 
  • #48
In a dense plasma focus, you essentially have a coaxial electrode system. One end is insulated and a huge amount of current is released in a microsecond from a marx generator. The plasma sheath propagates up like a plasma gun (lorentz force) and at the top of the electrode system, some hydrodynamic shock effects occur which result in the formation of an extremely dense plasma column. Fusion occurs, although the lifetime is of the order of nanoseconds due to instabilities.

The dense plasma focus is useful as a neutron source. It would be difficult to focus the laser pulse into the exact location of the plasma column at the correct time.
 
  • #49
It would be difficult to focus the laser pulse into the exact location of the plasma column at the correct time.
Why so?I read that they trying to heat plasma focus with external electron beam.Is it more difficult to aim it with laser than with electron beam?
Also at least some experiments with heating of plasma focus with laser seem already been conducted and quite successful.
http://jap.aip.org/resource/1/japiau/v42/i13/p5884_s1?isAuthorized=no [Broken]
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0910345
So it seem to be principally possible back in 1970-es.
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?
 
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  • #50
Stanley514 said:
Is it possible to combine dense plasma focus and fast ignition approaches?
They claim that plasma focus is very dense.If so, it could be easily ignited with
picosecond laser and thermonuclear explosion should happen?

One would have to heat it from all sides equally. It is not easy.
 
  • #51
Stanley514 said:
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.
 
  • #52
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.
 
  • #53
Stanley514 said:
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.
 
  • #54
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
 
  • #55
Stanley514 said:
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.
 
  • #56
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.
 
  • #57
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!
 
  • #58
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?
 
  • #59
Velikovsky said:
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.
 
  • #60
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?
 
  • #61
Stanley514 said:
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
 
  • #62
Stanley514 said:
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.
 
  • #63
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. Gilsona, R. C. Davidsona, P. C. Efthimiona, I. D. Kaganovicha, J. W. Kwanb, S. M. Lidiab, P. A. Nib, P. K. Royb, P. A. Seidlb, W. L. Waldronb, J. J. Barnardc, A. Friedmanc
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
 
<h2>1. What is fusion and how does it work with accelerators?</h2><p>Fusion is a process in which two or more atomic nuclei combine to form a heavier nucleus. This process releases a large amount of energy, which can be harnessed for various purposes. Accelerators are used to create the extreme temperatures and pressures necessary for fusion to occur. They accelerate particles to high speeds and then collide them together, causing fusion reactions to take place.</p><h2>2. What types of accelerators are used for fusion?</h2><p>There are two main types of accelerators used for fusion: magnetic and inertial. Magnetic fusion uses powerful magnets to contain and control the hot plasma needed for fusion reactions. Inertial fusion, on the other hand, uses lasers or particle beams to rapidly heat and compress a small pellet of fuel, causing fusion to occur.</p><h2>3. What are the potential benefits of fusion with accelerators?</h2><p>Fusion has the potential to provide a nearly limitless source of clean energy. It produces no greenhouse gases or radioactive waste, making it a much more environmentally friendly option than traditional energy sources. Additionally, fusion fuel is abundant and can be easily extracted from seawater.</p><h2>4. What are the current challenges in achieving fusion with accelerators?</h2><p>One of the main challenges in achieving fusion is creating and maintaining the extreme conditions necessary for fusion reactions to occur. This requires advanced technology and materials that can withstand high temperatures and pressures. Additionally, controlling and confining the hot plasma is a difficult task that scientists are still working to improve.</p><h2>5. When do scientists predict that fusion with accelerators will become a viable energy source?</h2><p>While significant progress has been made in fusion research, it is difficult to predict an exact timeline for when fusion will become a viable energy source. Some estimates suggest that fusion power plants could be operational within the next few decades, but further research and development is needed to overcome the current challenges and make fusion a practical and cost-effective option for energy production.</p>

1. What is fusion and how does it work with accelerators?

Fusion is a process in which two or more atomic nuclei combine to form a heavier nucleus. This process releases a large amount of energy, which can be harnessed for various purposes. Accelerators are used to create the extreme temperatures and pressures necessary for fusion to occur. They accelerate particles to high speeds and then collide them together, causing fusion reactions to take place.

2. What types of accelerators are used for fusion?

There are two main types of accelerators used for fusion: magnetic and inertial. Magnetic fusion uses powerful magnets to contain and control the hot plasma needed for fusion reactions. Inertial fusion, on the other hand, uses lasers or particle beams to rapidly heat and compress a small pellet of fuel, causing fusion to occur.

3. What are the potential benefits of fusion with accelerators?

Fusion has the potential to provide a nearly limitless source of clean energy. It produces no greenhouse gases or radioactive waste, making it a much more environmentally friendly option than traditional energy sources. Additionally, fusion fuel is abundant and can be easily extracted from seawater.

4. What are the current challenges in achieving fusion with accelerators?

One of the main challenges in achieving fusion is creating and maintaining the extreme conditions necessary for fusion reactions to occur. This requires advanced technology and materials that can withstand high temperatures and pressures. Additionally, controlling and confining the hot plasma is a difficult task that scientists are still working to improve.

5. When do scientists predict that fusion with accelerators will become a viable energy source?

While significant progress has been made in fusion research, it is difficult to predict an exact timeline for when fusion will become a viable energy source. Some estimates suggest that fusion power plants could be operational within the next few decades, but further research and development is needed to overcome the current challenges and make fusion a practical and cost-effective option for energy production.

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