A few people know that I worked at Los Alamos on fusion stuff back in college. It was one of those jobs halfway between an internship and a real job. For a student it paid quite well too. Unfortunately it wasn't the best example of big science spending and I became rather disenchanted with the whole thing. One of the big problems of working for the government, even if only indirectly, is all the bureaucracy. Once I got my security clearance and could see what was going on I wasn't too impressed either. The type of fusion I was mainly working on was ICF fusion. That consisted of taking a very large laser and hitting a tritium pellet from all sides. Ideally the pressure is such that you get fusion. The problem is that as it heats up or explodes that you get blasts of plasma going the wrong way, destroying your symmetries and stopping fusion. Things are more complex than that, but I have no idea what has been declassified since the same physics is used in nuclear weapons. Indeed a lot of what we did was weapons physics. So I can't really get more specific than that, although there's plenty of stuff on the web that describes in depth everything we were doing. But that's really just a tangent to explain why I'm posting this about sonic fusion.
According to New Scientist the success of sonic fusion announced a while back to many a doubting Thomas has been replicated. This process has also been called bubble fusion because of its use of standing waves to help generate bubbles in acetone. (Acetone with deuterium instead of hydrogen atoms I believe) There are still a lot of skeptics. After all cold fusion had some purported replication initially. But apparently a lot of people are becoming believers. It sounds like at Oak Ridge in particular they've bent over backwards to ensure that the problems that beset cold fusion don't happen. That's very wise.
Sadly the full New Scientist story is for subscribers only. Science Blog has a fairly good write up about the news though. A few excerpts from New Scientist.
Unlike claims for cold fusion, the idea of bubble fusion is not left-field. The phenomenon at its heart is sonoluminescence, the mysterious flash of light emitted when bubbles are blasted with powerful sound waves. The waves produce regions of high and low pressure in the liquid, and bubbles form in the regions of low pressure, where the liquid simply boils. Then, as the bubbles experience intense pressure, they collapse and emit light - though no one fully understands why.
For many years the eerie glow was little more than a curiosity because the bubbles were so difficult to control. But that all changed in 1992 when a team led by Felipe Gaitan at the Naval Postgraduate School in Monterey, California, discovered how to trap a bubble in a stationary or "standing" wave and vary the pressure so that it would expand and collapse in a controllable way, each time emitting a pulse of light. For the first time it became possible to study sonoluminescence in detail.
Gaitan's team found that the bubbles produce a range of wavelengths of light, including ultraviolet. To create such energetic light, they reasoned, the temperature within the bubbles must exceed 10,000 kelvin, perhaps reaching as high as 1 million kelvin.
The new experiment was different in a number of crucial ways. Instead of looking for fusion neutrons shortly after firing the initial burst, the group monitored their arrival continuously throughout the experiment. The results show that the initial burst used to seed the bubbles gradually dies down. Then, after a short time, a couple of peaks appear. These peaks, claims Taleyarkhan, are the bursts of neutrons generated in fusion reactions.
Of course the big question is whether the process can be made self-sustaining and whether there is a way to feasibly build a useful reactor out of it. That last point is the bane of some fruitful approaches to fusion. After all the big problem with ICF was that you had to have a tritium pellet in a perfectly spherical ball exactly positioned so that the light causes a symmetrical implosion. Even with various tricks that I can't speak about, it doesn't appear to be the sort of thing one could use to generate useful amounts of electricity. Magnetic fusion still seems the most probable source of fusion power. However that's always had troubles and isn't as "clean" as some might wish. (After all the big problem with fission, that is actually a pretty good power source, is all the radioactive materials one has to dispose of)
Rensselaer has released an excellent press release. (Note link moved into text for convenience -- CG)
"Moving at about the speed of sound, the internal shock waves impacted at the center of the bubbles causing very high compression and accompanying temperatures of about 100 million Kelvin."
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