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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."
Surpassing break even is easy, we did it decades ago... What we are missing is a really big boiler, to make it work.
Statistical evidence of fusion at this level is indeed impressive; however, while fusion experiments such as this others remain below the break-even point, they shall yet be little more than a labtable source of neutrons. We await developments from the latest in the field.
of Cold Fusion, a technology that promises clean power in future (and prevent wars over oil). Just wondering why governments are so indifferent to Cold Fusion.
hilarious
It's possible to build boosted fission primaries with fission efficiency up to about 50%. Such have been built and weaponized. Modern US devices have less efficiency (around 15%, in rough terms) because they are designed to use as little fissile material as possible and to be one-point safe, and also to have limited overall fission yield. Those requirements lead to less efficient weapons than are possible and were used in the past.
Second, fusion, stages can be both highly efficient (50% or more of the possible fusion energy content) and have very high multiplication ratios of input to output energy (factor of 25 is possible, with factors of 8-15 in deployed US weapons), even before you double it again with a fissionable tamper third stage.
Look at references like the Nuclear Weapons FAQ at http://nuclearweaponarchive.org/
Once you build a Farnsworth Fusor, you have a tabletop nuclear fusion device. Which part of "Fusor" was unclear?
If all you want is neutrons and to violate your local Nuclear-Free Zone, just stop at that point...
You are so wrong it's not even funny.
The industrial revolution started because of forest depletion in England which meant that they had to switch to coal. In order to get to the coal they invented the steam engine to pump water out of mines and lift people into and out of them. The invention of the steam engine had the wonderful side effect of bringing forth the industrial revolution from which we all benefited.
If you want to read about the reasons for societal development and collapse by a academic whose works on civilization have stood the test of time and explain the Roman, Mayan, Mezoamerican and Egyptian collapses all with the same theory I suggest you read Tainter's collapse of complex societies. The west has saved itself from collapse for longer than any other civilization out there because we have had the wonderful luck to constantly innovate ourselves out of the corners we get into. There were many times throughout the Renaissance and the industrial revolution that European society could have collapsed but we always managed to pull ourselves out of it via technolgy.
In this case, the important ingredient is deuterium, which can be extracted from sea water. If there is anything that Earth has a lot of, it's sea water. So with any luck you are wrong.
I don't care if it's 90,000 hectares. That lake was not my doing.
5+ standard deviations against the control is interesting. Should be easy to reproduce. (or not).
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
The 'law' you are misstating, really says: One cannot extract more work out of a system then contained in enthalpic release the powers the system. (i.e. if our reaction produces 1 J of energy, the most usable work we can hope to get out of it is 1 J). Thanks to E=mc^2 the energy you get out of a nuclear reaction is very very large, and you don't care about converting all that energy into useable work.
However, as a geek, I know that the Dark Ages were as much caused by the change in the fuel economy from wood to coal as the retreat of the Roman Empire.
Or in other words, "as a geek, my knowledge of history is really skewed".
The Dark Ages were hundreds of years before the switch to coal. Coal mining started around the time the dark ages were ending (circa the 11th century), and the fuel economy didn't switch wholesale until hundreds of years after that.
-- Alastair
Whatever they hit, it becomes radioactive and more fragile.
An exaggeration. Hydrogen atoms, for example, merely become deuterium atoms, which are not radioactive.
Which is why neutron shielding tends to be made of things like lightweight polymers that contain lots of hydrogen atoms. (In the early days before modern plastics, they used paraffin wax.)
There are other materials that can happily absorb a neutron and go from one stable isotope to another.
-- Alastair
You can get tabletop fusion with a TV high voltage supply, a glass bulb, some wire, and deuteriums gas. That's been known for decades and is used as a neutron source commercially. People build those things for science fairs. It's called the "Farnsworth Fusor" (I know, in light of Futurama it sounds like a joke, but the fictional character was named after the real one).
Why don't we all have flying cars, then? Because you can't get a net energy gain with the Farnsworth Fusor--it seems to be impossible in general to do so, the numbers just don't work out.
Of course, even if you do make it efficient, it's not exactly "clean energy": even with so-called aneutronic fusion, a few percent of the fusion reactions will generate neutrons, which, for realistic power generation, results in a neutron flux that causes the power generation to be quite dirty. Not as dirty as fission--disposal should be easier--but don't expect something harmless you can just run in your basement.
So, tabletop fusion isn't really anything impressive: there are probably lots of ways of getting fusion on your tabletop. The question is how you make it efficient enough to useful amounts of energy out of it. And cavitation seems no more promising there than inertial confinement in the Farnsworth Fusor. But maybe if enough people keep playing around with this, someone will get lucky and find something that works.
OK then, Just in case anyone else is as thick as me: Don't check the parents of these replies unless you want to spoil your pleasure in reading the latest Harry Potter.
RTFA:
Researchers have estimated that temperatures inside the imploding bubbles reach 10 million degrees Celsius and pressures comparable to 1,000 million earth atmospheres at sea level.
This is NOT cold fusion, this is sonofusion.
Iraq: war to save the U
About coal being worse than nuclear, I have not the best references, but here are a few:
/ FS-163-97.html / colmain.html
http://geology.cr.usgs.gov/energy/factshts/163-97
http://www.ornl.gov/info/ornlreview/rev26-34/text
http://yarchive.net/nuke/coal_radiation.html
Remember the year 2000? They promised us flying cars. They delivered the PT Cruiser...
The Soviets built some nuclear-powered ice breakers.
"Long run is a misleading guide to current affairs. In the long run we are all dead." (John Maynard Keynes)
I may not be the GP, but I'll throw in my $.02 as a fusion science researcher. (I work on a magnetic confinement device myself.)
1) The running joke of fusion is that it's always 30-50 years away. This is more due to meager funding levels than anything else. At a talk by a PPPL scientist a few years back, it was mentioned that if one plots the price of oil and the amount allocated for fusion research versus year, they track rather nicely. (The 70's were a great time to be in the field!)
Why the meager funding? Fusion researchers kind of shot themselves in the foot in the late 50's and 60's, before much of the underlying plasma physics was well understood. TFTR (the Tokamak Fusion Test Reactor, built in the late 70's, ran through the 90's) turned up physics phenomena that were unexpected and needed to be understood. (That can still be said for many devices today, which are built to specifically analyze these phenomena.) When Nature deals you a bum hand, you have to go back to the drawing board -- and push things off for another decade. Politicians don't like that -- especially when they've been coerced into thinking past their next election!
ITER will be a very large-scale test device. Some of the phenomena that we see disrupting our current experiments are related to physical device size. Additionally, fusion power production is volumetric, while losses from the plasma come from the surface area of the confined plasma. Therefore, scaling up the size will boost fusion output, making it easier to "breakeven" (power out == power in) and, in ITER's case, very likely "ignite" (after reaching a critical temperature, you can turn off external heating and the plasma burning supplies the rest).
Of course, such scaling takes Lots of Money. Superconducting magnet coils are pricey; so is requisite neutron shielding. Current designs incorporate a Lithium "blanket" which will both absorb the 14 MeV neutrons (shielding) and produce tritium (amazingly, more T than you seed the plasma with initially!). One of the biggest question marks is in the field of materials. Nothing has been built that is going to take the neutron punishment that ITER will dish out to plasma-facing surfaces. It is such an important task to design materials that can sustain bombardment that a separate facility will be constructed simultaneously with ITER in Japan to study neutron bombardment exclusively. This has implications in the divertor material (high-Z tungsten or something lighter?) as well as blanket design.
2) My personal opinion is that it is best to stick with our Gen-IV nuclear plants when it comes to fission. These are meltdown-proof, high-efficiency plants that are designed for rapid implementation, should there be a willing buyer. A tabletop-size fusion device would be a relatively inefficient method of starting a fission plant; there are plenty of natural neutron sources that can be made by mixing radioactive materials together. Essentially, it'd be cheaper to use our existing designs for a big fission plant than mixing a fusion reactor's blanket design with a subcritical fission design.
"The Health Hazards of Not Going Nuclear", by Petr Beckman. Out of print and somewhat dated (about 20 years old), but goes into the different problems with coal versus nuclear power. Multiple copies available at abebooks.com
Energy company buys IP and makes it illegal to own or operate a fusion reactor. Business as usual.
President Cheney declares cold fusion a state secret. See above.