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More Evidence for Tabletop Fusion
heptapod writes "Researchers at Purdue University have statistically significant evidence that their tabletop fusion experiments were successful. Yiban Xu's experiment different from an earlier Oak Ridge experiment using a different and cheaper source of neutrons than Oak Ridge's pulse neutron generator. Surpassing break-even point still eludes the grasp of science."
"When it's time to railroad, you get railroads." Or however the saying goes.
This question is one I've been thinking about for a few years now due to an idea for an invention I've got (not cold fusion, though), plus some stories I know of. The most relevant one is an episode of Outer Limits (the series from the 90s, not the one from the 60s).
In the story, an expelled physics student detonates a small 'cold fusion bomb' in a campus clocktower as proof of the technology, then takes a physics class hostage with another device. He demands that the people who have tormented him in the past be brought to the courtyard and shot in front of him, or he'll detonate the more powerful device he's got with him.
While the military is trying to figure out what the hell it was that detonated (since they don't believe in a cold fusion bomb), the negotiator is trying to figure out what the deal is with the hostagetaker. It comes out that, among other things, he believes there's a reason we've not found any signals from other species. The cold fusion technology is so simple that anyone can make it. When a species gets advanced enough to realize how easy cold fusion is, he says it's inevitable that a species will destroy itself before it can get mature enough to handle its technology. The negotiator then says, well, tell us what led you to the idea, and we can try to steer science around that until we can mature enough to handle it. The guy thinks back to what started him on the path to cold fusion - a physics test with the question, "Demonstrate why cold fusion is impossible."
I'd say it's inevitable that we WILL have this technology. How simple it winds up being is unknown at this point, of course, but hopefully it'll be complex enough that not every nut in a garage can do it.
I wouldn't toss ITER aside before I get to at least read the journal article on a few of these desktop setups. I'd still like to see what pressure they're operating at, temperature ranges, D/T enrichment, reaction rate, bubble size, mcnp models (a vised geometric plot at the least), fluent models, etc. I just don't trust science magazine or a run of the mill newspaper to publish groundbreaking science that's on par for an engineer to read, since those cater to people without much knowledge of the engineering feat discussed in the article. But that's the nuclear field (or any engineering for that matter), we're supposed to be skeptical as hell until it's widely duplicated. If I can do it in my lab, then I'll believe it. Or at least see it in someone else's lab who built it from scratch from nothing but the other researcher's blueprints. And controlling plasma with magnets isn't too hard, in fact it's down to nearly an exact science where only a few unknowns remain, mainly the occurance of MARFE's, diverter material protection, and so forth. The largest problem lies with protecting the magnets from the 14-MeV neutron flux exiting the core. But still, I wouldn't toss aside ITER just yet. It's got some work to do, but it's a pretty sound model for a large scale fusion power plant.
Where's the nuclear powered car we were promised back in the 1950s?
Some genius figured out that providing every man, woman, and child with sufficient nuclear material to create an atomic pile wasn't such a good idea?
From a technology perspective, there were a few other problems as well. Off the top of my head:
- Radiation: You need a lot of shielding to stop the "hard" stuff like Gamma, Neutron, and X-Ray bursts from escaping a functioning pile.
- Weight: All that shielding results in a lot of extra weight.
- Inefficiency: A "simple" atomic pile may be relatively safe (from a runaway reaction perspective), but it's not particularly efficient, nor can it be actively controlled.
In any case, the Ford atom car was never seriously developed. It was just an "Atoms for Peace" idea that was kicked around as a promotional gig.
A far better use for nuclear tech is in Merchant ships. Today's merchies pay extraordinary amounts for diesel fuel, have limited range, and burn fuel at the rate of gallons per feet. Nuclear reactors could provide these ships with more cargo space (no fuel tanks!), greater speed, longer endurance, and better turn-around times.
Unfortunately, the case of the NS Savannah turned off the private sector to the idea of a nuclear merchant ship. There was no real problem with the ship herself, but rather the fact that she was ahead of her time (crude was still VERY cheap back then) and one of a kind (no infrastructure to support her) meant that she couldn't compete in the market.
The equation today is a very different one from the equation back then, but concerns related to the control of reactors and nuclear fuels have placed road-blocks in the way of reviving the idea.
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Not only that, but fuel for very large diesel engines contains lots of residual oil, and is very high in sulfur. 5000 ppm plus. I understand that England recently traced the source of some acid rain problems to maritime activity. They've practically eliminated their sulfur output from coal power plants, etc, so boats are now the biggest producer.
That heavy diesel fuel is nasty stuff. Basically, its what's left over after they boil off all of the gasses, gasoline, kerosene, road use diesel fuel and the lower grade heating oils. They have to pre-heat it quite a bit to get it to burn in an engine, otherwise it's about as good as filtered crude oil--slightly less viscous.
Nuclear power would be a huge step forward in this area... I can't agree more. Throw in some modern reactor and propulsion designs and you'd have a terribly efficient and manuverable ship. Might even make fuel a bit cheaper for the rest of us if it caught on... Bonus.
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There was a BBC Horizon documentary on this nuclear fusion sonoluminescence phenomenon that casts strong doubt on the validity of previous work conducted by this researcher. The acid test for the occurence of fusion is the release of a neutron at the exact instant that the flash of light from sonoluminescence occurs. The Horizon team used a detector that can record the neutron releases at the required instant in time. After recreating Taleyarkhan's experiment according to his published journal papers, results were disappointing. None of the neutrons that were detected occurred at the same instant of any of the sonoluminescence flashes. The extra neutrons were explained away as originating from the emitter used to generate bubbles, or from external sources. No doubt rivals will challenge the statistically significant tritium claim. Tritium does occur naturally in significant quantities in any mass of heavy water (deuterium oxide).
Unfortunately, there are still problems with modern-day pirates in a few places in this world. Worrying about the loss of a standard diesel powered ship is bad enough, but the loss of a nuclear powered ship would be even worse.
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