Focus Fusion On Google Tech Talks 141
Henning Burdack writes "Eric Lerner talks on Google Tech Talks about Focus Fusion, which would be a much cheaper and more feasible technology as a fusion energy source than any other current approach, based upon the dense plasma focus device. The technology will use hydrogen-boron fusion with direct induction of ion energy and photovoltaic conversion of x-ray emission, obviating the need of a steam-cycle and thus resulting in higher efficiencies. High temperatures of 1 billion Kelvin (100 keV) have been reached years ago. It only needs $2 million in funding and two years of research for a proof of concept, and maybe four more years for a prototype with positive energy output. In contrast to other fusion efforts it utilizes the natural instabilities of plasma instead of fighting them. Focus Fusion has been discussed on Slashdot before, and a patent application is also available, going a bit more into detail."
Re:Possible conflict of interest (Score:5, Informative)
By itself no, however his wiki entry [wikipedia.org] create strong suspicion of crackpottery:
-graduate without completing a degree
-author of alternative cosmology theory denying Big Bang
-denial of quasar as blackholes
-life-long political activist
So far not so crazy (Score:5, Informative)
I don't know about this guy's background, but so far (still watching) he hasn't said anything crazy that signifies obvious crack-pottery. There's been o zero-point energy nonsense, and he's using standard terminology to explain things in a way that would make sense to someone with a little background in the subject. The new bit seems to be clever use of plasma instability to get the energy density required to initiate fusion. I'm not a plasma physicist (just particle physics), so I can't critically evaluate the details of the method. So far I'd believe this is plausible, but I don't know enough to be willing to give this guy any money.
And for gosh-sakes, fix the article summary. keV = kilo electron volts, not Kelvin!
More of a research device (Score:5, Informative)
This is one of a number of devices that can produce some fusion, but don't put out more energy than is put in. Forty years ago, this idea looked more promising. There was a fusion demo of a "plasma pinch" fusion system at the General Electric pavilion of the 1964 World's Fair. So far, no variation on this scheme has come even close to breakeven.
Re:So far not so crazy (Score:1, Informative)
- Actual experiments at various scales
- Multiple institutions testing these ideas (I don't mean the 3 companies he lists at the beginning, but rather the various researchers working on dense plasma focusing.)
- Acknowledgment of challenges, and explanation of how they were overcome.
That still doesn't say whether it's a practical power source, but at least he is starting with reasonable science.Re:Possible conflict of interest (Score:1, Informative)
I looked at the talk page for it also, the ban is related to the guideline http://en.wikipedia.org/wiki/Wikipedia:Conflict_of_interest#Self-promotion [wikipedia.org]
Here are the findings of fact,
"Eric Lerner
7) Elerner (talk contribs deleted contribs logs block user block log) is Eric Lerner, an advocate of the plasma cosmology theory. He is engaged in promotion of a "plasma focus device," utilizing a hydrogen-boron nuclear reaction [72] [73].
Passed 8-0 at 02:33, 3 December 2006 (UTC)
[edit] Self promotion by Elerner
8) Aneutronic fusion, which Elerner has edited extensively is, in part, an treatment of the "plasma focus device" which he is engaged in supporting and raising money for [74] as the director [75] of the Focus Fusion Society.
Passed 8-0 at 02:33, 3 December 2006 (UTC)
"
and the resolution
"Elerner banned
7a) Elerner is banned from editing Eric Lerner, Plasma cosmology, Aneutronic fusion, and any pages, excepting talk pages, related to his real-life work.
Passed 5-0 with 2 abstentions at 02:37, 3 December 2006 (UTC) "
From reading the dispute resolution page - it doesn't appear to me that the judging committee acted in a fair way.
Here we go again. (Score:5, Informative)
Now, the issue with fusion using fuels with higher atomic number than hydrogen is that the plasma will contain much more electrons, and this dramatically increases the amount of energy lost as bremsstrahlung when the electrons collide with the nuclei (the increased mass of the nuclei also plays a part ). Direct conversion of X-rays could theoretically help alleviate this as it would allow you to feed the lost energy back into the plasma, problem is, photo-voltaics have nowhere close to 100% efficiency.
Aneutronic fusion has advantages. You don't have to worry about neutron damage to the reactor vessel. However, when you look a bit closer at it, this isn't such a large advantage after all, because the neutrons are actually quite useful in that they deposit the energy over a quite large volume when they are being absorbed, reducing the stress caused by heating in the device. If it wasn't for the neutrons you would see most of the heat deposited in a comparably thin layer of the plasma-facing compounds. The counter for this is that aneutronic fusion releases the energy as charged particles, potentially allowing for directly converting the energy into electricity.
Basically, what this whole thing boils down to, is if you are able to achieve sufficiently good direct-conversion efficiency to counteract the increased X-ray losses due to the higher atomic numbers associated with aneutronic fusion. This is why you often see claims of breakthroughs in aneutronic fusion together with claims of either a non-maxwellian velocity distribution or some other remarkable way to reduce X-ray losses. A plasma with a maxwellian velocity distribution cannot sustain aneutronic fusion without being either very large and dense (to re-capture the X-rays) or by somehow capturing the lost X-rays after they leave the plasma and feeding the energy back into it.
For a non-maxwellian velocity distribution your problem is that even at optimal energies a collision is much more likely to scatter the ions than it is to cause fusion, and restoring the non-maxwellian velocity distribution will require energy (no, you don't get to violate the second law of thermodynamics I'm afraid ). For capturing X-rays your problem is to achieve a good enough conversion efficiency to make up for the dramatically increased X-ray losses.
With the exception of a few unconfirmed claims, nobody has been able to resolve the above problems (thou Bussard was quite vocal about his polywell device ) and this is pretty much why modern fusion power research uses D-T fusion. It gives the highest amount of energy for the lowest temperature and X-ray losses, at a maxwellian velocity distribution.
Re:Good comprehensive video... (Score:5, Informative)
Briefly there are two problems:
1. ordinary hydrogen is very hard to fuse. Even at the centre of the sun the average proton takes about 10^10 years to fuse.
Since the comrpressed interstellar gas is streaming through your ship at roughly lightspeed, even if "pinch" in your magnetic fields is 1km long, you have to get a decent proportion of it to fuse in 3 microseconds, so you need to achieve, in your pinch, temperature and density far far higher than at the centre of the sun. This seems difficult at best.
2. the interstellar medium (we now know) is best thought of as more like a froth than a uniform gas. Supernova shocks and other upsets clear "bubbles" and after a while almost all the gas ends up packed into relatively thin "bubble walls". Incoveniently, the Sun is sitting in the middle of a bubble several light-years across, so the interstellar gas is a very very thin round here.
Steve
Re:Asked a Plasma Physicist About This (Score:4, Informative)
Re:Asked a Plasma Physicist About This (Score:4, Informative)
Pretending that this is a non issue without backing up with some calculations/data is bad science. Especially when there is quite a lot of analysis indicating that at best they get around 3-5% of the power out as they put in (real devices less than 0.001% or worse). Thus without some high efficiency (>>90%) power recirculation method they can't work as a power production device.
This view is the general consensus of held by physicist, not just my view.