Is there any difficulty to construct a laser set they describe? It should be pretty easy to do?I am not sure, but I think the answer to your question is "neither". I think it is still considered a promising approach which has not yet been experimentally verified because the necessary laser hardware isn't there yet. Anybody else know more?
Take a look at the scale of the lasers at the National Ignition Facility. Now you have to build a new laser with a tighter focus and a very short pulse width and integrate it with the other 192 lasers which are already in place. I don't think I would describe this as "pretty easy to do."Is there any difficulty to construct a laser set they describe? It should be pretty easy to do?
EulersForumula,Fast ignition is pretty much dead. We can't make the electrons do what we want them to do. There is little funding left for it.
What you are describing is an x-ray backlighting diagnostic. This is different than trying to ignite the compressed fuel with a beam of hot electrons.
It was concluded in a National Academy of Sciences report last year that fast ignition was not the most promising path to fusion due to complications with controlling the fast electron beams. Many of the scientists who specialized in fast ignition are now changing research directions.
EulersFormula,Why are my claims erroneous? The report specifically quotes " Conclusion 4-5: At this time, fast ignition appears to be a less promising approach for IFE than other ignition concepts." Complicated target design and problems with laser-target energy coupling were cited.
You can argue all you want about how we have the technology to create the beams that we want, but it doesn't change the fact that we are unable to achieve good energy coupling between the beam and target. You are delusional if you think fast ignition is a "hot topic" in the ICF community.
What discourages the alphas from going their own separate ways ?Boot-strapping results when alpha particles, helium nuclei produced in the deuterium-tritium (DT) fusion process, deposit their energy in the DT fuel, rather than escaping.
EulerFormula,You are giving me a link of a fast ignition simulation dating more than a year ago. Can you tell me what useful results have been generated with since then?
I'm also not saying that there is nobody in the US who is studying fast ignition, but I am seeing a trend of researchers moving away from it. If you really do not notice this, then I am guessing that you are not actively involved in the ICF community.
If we cannot understand how normal cryo implosions are performing, then how can we possibly understand what is going on in a fast ignition scheme which has much more complicated targets?
I also don't understand your point about the hight foot campaign. That has nothing to do with fast ignition. They increased the adiabat to stabilize their implosions.
The goal of controlled fusion is to obtain sufficient energy from the alphas to 1) heat a magnetically confined plasma, or 2) release maximum amount of thermal energy.
We can't build a femto or attosecond laser with sufficient intensity to "spark" the fusion reaction. In order to spark fast fusion you need to deliver sufficient energy to your target. As you go to shorter pulses, the necessary intensity of your laser increases.Initially they proposed to use a picosecond laser as the ignitor in fast fusion. What if instead we use femtosecond or even attosecond laser for this purpose? Could it change conditions of fast fusion drammatically or not too much?
What do you mean as "intensity"? Lasers are characterized by power and energy. As we go to shorter pulses their power automatically increases, but energy requirements (for the fusion) diminish. The very point of fast ignition is to use picosecond laser which has higher power, but much smaller energy demands. I wonder what will happen if they will proceed to even much shorter pulses.We can't build a femto or attosecond laser with sufficient intensity to "spark" the fusion reaction. In order to spark fast fusion you need to deliver sufficient energy to your target. As you go to shorter pulses, the necessary intensity of your laser increases.
And lets not ignore all the physics of the laser-plama interactions. These tend to get more detrimental as you go to extreme laser intensities.