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http://news.uns.purdue.edu/html4ever/20 … *Bubbles**
*Sound waves to produce nuclear fusion reactions? They're predicting many uses for this technology.
"The technology might one day, in theory, lead to a new source of clean energy."
How does this bode for future space colonists, etc.?
--Cindy
We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...
--John Sladek (The New Apocrypha)
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It may not bode at all. Or it may be the greatest thing for space exploration since the telescope. Hard to say until we know whether or not it can produce enough power to reach breakeven.
As an example, just producing nuclear fusion reactions without reaching breakeven is something that can be done with an existing technology called a Farnsworth Fusor. It's a little tabletop-sized device invented by the fellow who invented television. It ionizes gases using static electric fields and circulates them until they accelerate to speeds/temperatures where they will fuse. I suspect a Farnsworth Fusor produces a higher rate of fusion than they're currently seeing for sonoluminescence.
Sadly, it's still not enough to reach breakeven and produce more power than it takes to run the reactor.
Happily, it's fascinating that we already have tested, proven technology to create a fusion rocket engine today if we just drop this foolhardy preoccupation with wanting it to bootstrap its own power source.
How will nuclear fusion turn out as a technology? Well, that depends as much on what you want from it as on what it can give you.
"We go big, or we don't go." - GCNRevenger
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A friend of mine actually built a tabletop fusion reactor in high school (Farnsworth, not bubble). He said that it was not really very difficult. The difficult thing is making it efficient enough to get a net power gain.
Building a fusion reactor is like building a fire. Building a fusion reactor that generates useful power is like building a steam engine.
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From what I've read about Fusor technology, the biggest hurdle is having particles hit the accelerating electrodes. Because of the design, the electrode is within the particle field and the vast majority of the particles quickly impact the electrodes and don't get a chance to fuse. If someone clever were able to design an electrode that could deflect particles around it, there's no reason that a fusor couldn't get well over break-even.
Buildinga rusor on high school is quite impressive. I woudn't even try to build one of those on my own with all of the high voltage circuits. However, on the scale f fusion devices, the fusor is pretty trivial compared to, say, a tokomak.
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Heehee, hi-voltage circuitry is fun!
Friend and me, we built some kind of Rumkorff (sp) sparking generator ( primitive 19th Century device that generates hi-voltage sparks, very impressive)) as a science project at school, eons ago, and when we demonstrated it at the 'open-days' (visitor days) it fried several other nearby electronics projects, just from its horrible interference... it took a while before people realised what was the cause of their stuff glitching like mad... (we actually kinda hoped that would happen, grin...)
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it's fascinating that we already have tested, proven technology to create a fusion rocket engine today if we just drop this foolhardy preoccupation with wanting it to bootstrap its own power source.
I will steal this and temporarily use it as my .sig!
Seriously... Would it be usable?
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Given enough power to run it, a modified Fusor could be operated just like any other ion drive, only with an exhaust velocity between 250km/s and 10000km/s, depending on design.
A useable rocket engine would likely need more power than the tabletop demonstration units, because its confinement time drops when you're draining the plasma out of a rocket nozzle. However, the tabletop units typically only use 100W to 1000W -- less than a toaster. (The charge developed is more important than the current.)
"We go big, or we don't go." - GCNRevenger
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So why didn't no-one investigate this further, the idea is far from new... Power requirements too much to be any good?
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The fusion research community is highly politicized. The tokomak folks have basically taken over and any alternate designs have been marginalized, relying on shoestring budgets to keep operating. On one hand, the tokomak design is the most promising but on the other, the tokomak design has some serious issues which really recommend that we keep looking at alternate issues.
If you look for a history of the Fusor design, it's clear that it was internal company politics rather than design flaws that killed mainstream fusor research. Although ir's quite possible that the fusor design is inherently incapable of breakeven, there's no reason why it should be ignored as much as it is.
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Bad phrasing... I meant, why isn't it used for propulsion or at least researched, break-even or not...
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It is being researched, however current designs require too much power and produce too little thrust.
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It is being researched, however current designs require too much power and produce too little thrust.
Hmm... Given the common occurence of the word "megawatt" in articles on the famous VASIMR drive, how much power is too much power?
The tabletop, non-rocket version of the fusor draws about as much power as a large TV - no megawatts there.
"We go big, or we don't go." - GCNRevenger
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The problem with those tabletop drive is that they would also produce essentially no thrust, even by ion engine standards. For a fusion drive to work it has to at least be in the neighborhood of breakeven or you might as well be using a standard ion engine with all the power you have to pump into the system.
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