Tomorrow I'm headed out to Madison for the biannual Innovative Confinement Concepts conference, so I may be offline for a while, possibly until Friday. They claim there's WiFi at the conference center, so maybe I'll be able to post from there. I'll certainly post a summary of goings-on.

The conference is a meeting of researchers working on so-called innovative confinement concepts (hence the name of the conference :-). An ICC is basically any fusion concept that isn't a Tokomak or an inertial confinement scheme. Tokomaks (and acronym from the Russian for "Toroidal Magnetic Chamber") are the current leaders in achieving fusion-relevant parameters of temperature, density, and confinement time. Unfortunately they are inherently pulsed devices, and they have other technical features that make them undesirable for power plants. People are working to make Tokamaks power-plant friendly, but progress is slow (as in everything related to fusion). The other mainstream fusion scheme is Inertial Confinement Fusion. This uses a solid pellet of Deuterium and Tritium which is compressed and heated by external energy input from lasers, ion beams, or X-Rays. Currently only lasers and X-rays are used, ion beams having fallen out of favor (for reasons similar to those for the loss of favor of ion beam weapons for BMD - it turns out the beams are damn hard to point and focus accurately if they have any decent amount of energy). I don't think anyone at this point honestly believes ICF is a real contender for power plants (though I could be wrong). The main reason ICF has solid funding is that the physics of the capsule implosion are exactly the same as the physics of the fusion stage of a thermonuclear weapon. In a weapon, X rays are generated by the detonation of a fission device, and passed via a carefully shaped reflector onto the surface of a Lithium Deuteride capsule, which implodes, fuses, and explodes. If you want to understand this process in detail, the ideal way to do it is to detonate small capsules under controlled conditions.

Anyway, the ICCs are the other guys, ranging in funding from ~$10 million down to ~$200K. They are the high-risk, high-reward segment of the fusion development portfolio. The designs range from minor variations on existing technology to outright Wile-E-Coyote designs. I personally believe that the ICCs are the best hope for getting fusion power on the grid in my lifetime, but that to really make things happen we need a fundamental paradigm shift in the fusion community. A lot of folks in the community don't get basic economics, and have little idea about how technologies have historically come into the commercial sphere. That's one of the things I'll be talking to people about at the conference.

Anyway, if you don't hear from me for a while, that's what I'm up to. If I can get decent net access I'll post on the goings-on.

A friend of mine studied cold fusion in college. But nothing came of that - did it? Too bad...

A question: for deuterium fusion to occur, must one have a very large number of atoms compressed in the same chamber/container/space ? Would it be easier to work with very small numbers of atoms?

If, say, instead of one big chamber with a macroscopic deuterium pellet, you split the chamber into many very thin electromagnetic tubes, and inserted a microscopic stream of deuterium ions in each one, would it be easier to compress and heat each stream individually?

It ought to be easier to grind small pebbles into powder, than to pulverize one big stone in a single blow... but I'm no physicist. :)

I'm no physicist either, but I think the best argument against your appoach would be the cube-square problem. Many small loci have a lot more surface area than one big locus of the same shape with a volume equal to the sum of the small ones. Too much heat gets away before it has a chance to help keep the "flame" going.

That said, it's only fair to note that the alleged acoustic cold fusion that's been in the news lately would, if it checks out, make a liar out of me as it apparently only works when the compression region is very small - i.e. microscopic.

A.R.Y: Cold fusion is well into pseudoscience lala land now. If I were you I wouldn't believe a word of the wild claims until they have extremely good experiments that have been repeated by skeptics. Past experience suggests this is not very likely, btw.

Dick: the square-cube law cuts both laws. Fusion reactors are going to be limited by wall loading (too many neutrons per unit area degrades the wall and it has to be replaced). This means larger reactors would have to operate at lower volumetric power density, which is bad for the ecomomics.

I'm interested in hearing how some of the odd concepts are working out. Dipole confinement, for example, seems well-suited to use in space (and is itself a spinoff of the study of planetary magnetospheres.) Magnetoinertial concepts also looked interesting to me.

Actually, so-called cold fusion has been going under a very low level of research, mostly because there's been a few loose ends that just didn't quite close. Recently DoE decided there's enough to it that they're re-opening their research. I don't recall all the details, but it turns out that deuterium that gets trapped in the electrode just may end up fusing. Most likely never going to be a practical energy source, but should provide insights into possible mechanisms of fusion, not to mention insight into the internal structure of the electrode material. So, it's a basic physics topic for the time being. (Unless someone has better info than my recollection of something that happened a few weeks ago.)

Anyway, I hope Andrew posts lots of good info when he gets back. Looking forward to hear the latest on the sonoluminescence front, as well as progress in the IEC world.

- Eric.

No, it's very unlikely that the deuterium ends up fusing. The radiation signature of fusion is unmistakable (in fact, deadly at any significant level of power output), and its absence means that in addition to the miracle of fusion occuring, you need another miracle of fusion occuring without radiation.

This is just like ESP or UFO research. The true believers keep piling on the reasons to avoid dealing with the contrary evidence.

Fusion cores are an order of magnitude more expensive than fission cores (per unit thermal power output), so it's important that the non-nuclear part of the cycle be as efficient as possible.

I just found a very interesting company that's come up with a technology for radically boosting the efficiency of powerplants. See this blog entry for more on it.

just checking to see if this will get through to my email inbox