A couple of points. The original work used neutrons as the nucleating site. Are you sure that alpha particles are now the particle of interest, why not fission fragments or the recoiling atom. The range of the alpha would be about 50 microns. Hydrodynamic forces might collapse them to a point, but its unlikely given the aspect ratio of the track. Also what would be the lifetime of such a microvoid.
The d-d reaction yields a 25 Mev output, against 4 Mev alpha (a nice little gain of 6 or so), so a chain reaction is not completely crazy, assuming every bubble resulted in at least one fusion. And assuming that the fused particle's seed void remains for the next cycle. Or even provided a seed for the current one.
Do all particles match the fusions? That is, is there at least one neutron for every alpha? Natural uranium is not the most prodigous producer of alpha particles, why not use a more radioactive source? Does the experiment scale with the amount of uranium salt used? The classic fusor is defeated by the presents of a physical electrode which ultimately intercepts the accelerated particles, what limits the sonofusion?
Sonofusion in the news again.
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Brian McDermott
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Re: The obvious question
The RPI group uses a proton-recoil fast neutron scintillator.
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Carl Willis
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Re: The obvious question
1) Very few fissions occur in this experiment, probably only a couple per minute, just to take a guess. They wouldn't have a noticable impact on the results.
2) the DD reaction has a total yield of 3.3 MeV, of which the neutron gets about 2.5 MeV through kinematic constraint. Watch the decimal point! However, there's still the possibility for an energy gain, since neutrons in the 10^4 eV range and up can still cause nucleation in a superheated liquid.
3) I think they chose uranium because it avoids the regulatory complications that would pertain to other strong, unsealed alpha emitters. It isn't the best choice from a functionality perspective.
4) The fusor has no possibility for chain-reacting critical behavior such as I outlined for sonofusion (and even then, I suspect the frequency of cavitation is an essential key to the possibility). Energy-recovery-wise, it has the same drawbacks as sonofusion, mainly that the energy produced by fusion either escapes the reactor or is converted into low-quality heat.
-Carl
2) the DD reaction has a total yield of 3.3 MeV, of which the neutron gets about 2.5 MeV through kinematic constraint. Watch the decimal point! However, there's still the possibility for an energy gain, since neutrons in the 10^4 eV range and up can still cause nucleation in a superheated liquid.
3) I think they chose uranium because it avoids the regulatory complications that would pertain to other strong, unsealed alpha emitters. It isn't the best choice from a functionality perspective.
4) The fusor has no possibility for chain-reacting critical behavior such as I outlined for sonofusion (and even then, I suspect the frequency of cavitation is an essential key to the possibility). Energy-recovery-wise, it has the same drawbacks as sonofusion, mainly that the energy produced by fusion either escapes the reactor or is converted into low-quality heat.
-Carl
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Richard Hull
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Re: The obvious question
As Carl noted uranium is avaialble in common water soluable compounds. Rest assured that did NOT dissolve a fertilizer bag load of u nitrate in the thing. Probably , it was only a few grams.
Alpha's would probably do a better job than neuts in nucleation as they would not thermalize over a long track, but spend their energy (4-5mev) in a massive form over a mico track. As they are evenly distributed in the fluid, there are no hot spots just uniform emission throughout the fluid.
Richard Hull
Alpha's would probably do a better job than neuts in nucleation as they would not thermalize over a long track, but spend their energy (4-5mev) in a massive form over a mico track. As they are evenly distributed in the fluid, there are no hot spots just uniform emission throughout the fluid.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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wbongianni
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Re: The obvious question
Richard:
The alpha emission is not a hot spot, but distributed over a 50 micron range. The nucleation spot is in the sub micron range, so the alpha track is huge by comparison. Also how does the nucleation track, diameter about 2-3 angstroms, remain around long enough for a cycle to trigger on it? A 25 kHz, means a 40 microsecond cycle.
The alpha emission is not a hot spot, but distributed over a 50 micron range. The nucleation spot is in the sub micron range, so the alpha track is huge by comparison. Also how does the nucleation track, diameter about 2-3 angstroms, remain around long enough for a cycle to trigger on it? A 25 kHz, means a 40 microsecond cycle.
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Richard Hull
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Re: The obvious question
By hot spot I meant the alpha emission is uniform thoughtout the liquid with no alpha hot spots.
The alpha emission is continous and as such goes on every second, every millisecond every microsecond, every femptosecond. It need not be timed to cyclic nucleation activities. Some fractional portion of alphas will be available at all instants in time.
Other alpha emitters would be far more desirable and efficient than uranium, but illegal or require complex NRC licenses or nasty radiation spill and cleanup efforts and containment.
The researchers used alphas mainly to shut down the "whiners" who poo-poo'd their neutron results for using a blast of neutrons to make neutrons.
There are no neutrons in uranium spontaneous fission reactions at the level of the few grams of U chemicals in the solution. At the dilution of the solution, very few sono-fusion, N related U fissions will occur, either. Once the fusion neuts slow to below 1mev in the fluid, they can't induce any fissions anyway.
It is like Carl said, a few fissions per sonofusion burst at best. These few neuts would create no noise issues in and amongst the true sonofusion blast of neutrons
Richard Hull
The alpha emission is continous and as such goes on every second, every millisecond every microsecond, every femptosecond. It need not be timed to cyclic nucleation activities. Some fractional portion of alphas will be available at all instants in time.
Other alpha emitters would be far more desirable and efficient than uranium, but illegal or require complex NRC licenses or nasty radiation spill and cleanup efforts and containment.
The researchers used alphas mainly to shut down the "whiners" who poo-poo'd their neutron results for using a blast of neutrons to make neutrons.
There are no neutrons in uranium spontaneous fission reactions at the level of the few grams of U chemicals in the solution. At the dilution of the solution, very few sono-fusion, N related U fissions will occur, either. Once the fusion neuts slow to below 1mev in the fluid, they can't induce any fissions anyway.
It is like Carl said, a few fissions per sonofusion burst at best. These few neuts would create no noise issues in and amongst the true sonofusion blast of neutrons
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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wbongianni
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Re: The obvious question
Here is the abstract in Phys Rev Let, 96:
Nuclear Emissions During Self-Nucleated Acoustic Cavitation
R. P. Taleyarkhan,1 C. D. West,2 R. T. Lahey, Jr.,3 R. I. Nigmatulin,4 R. C. Block,3 and Y. Xu1
1Purdue University, West Lafayette, Indiana 47907, USA 2Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA 3Rensselaer Polytechnic Institute, Troy, New York 12180, USA 4Russian Academy of Sciences, 6 Karl Marx Street, Ufa 450000, Russia
(Received 19 September 2005; published 27 January 2006)
A unique, new stand-alone acoustic inertial confinement nuclear fusion test device was successfully tested. Experiments using four different liquid types were conducted in which bubbles were self-nucleated without the use of external neutrons. Four independent detection systems were used (i.e., a neutron track plastic detector to provide unambiguous visible records for fast neutrons, a BF3 detector, a NE-113-type liquid scintillation detector, and a NaI ray detector). Statistically significant nuclear emissions were observed for deuterated benzene and acetone mixtures but not for heavy water. The measured neutron energy was 2.45 MeV, which is indicative of deuterium-deuterium (D-D) fusion. Neutron emission rates were in the range ~5×103 n/s to ~104 n/s and followed the inverse law dependence with distance. Control experiments did not result in statistically significant neutron or ray emissions.
©2006 The American Physical Society
The only number here is the 10e4 neutron/sec. which should be interesting to anyone here. Without need for a PNS, it could be verified by anyone with a moderate budget.
Nuclear Emissions During Self-Nucleated Acoustic Cavitation
R. P. Taleyarkhan,1 C. D. West,2 R. T. Lahey, Jr.,3 R. I. Nigmatulin,4 R. C. Block,3 and Y. Xu1
1Purdue University, West Lafayette, Indiana 47907, USA 2Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA 3Rensselaer Polytechnic Institute, Troy, New York 12180, USA 4Russian Academy of Sciences, 6 Karl Marx Street, Ufa 450000, Russia
(Received 19 September 2005; published 27 January 2006)
A unique, new stand-alone acoustic inertial confinement nuclear fusion test device was successfully tested. Experiments using four different liquid types were conducted in which bubbles were self-nucleated without the use of external neutrons. Four independent detection systems were used (i.e., a neutron track plastic detector to provide unambiguous visible records for fast neutrons, a BF3 detector, a NE-113-type liquid scintillation detector, and a NaI ray detector). Statistically significant nuclear emissions were observed for deuterated benzene and acetone mixtures but not for heavy water. The measured neutron energy was 2.45 MeV, which is indicative of deuterium-deuterium (D-D) fusion. Neutron emission rates were in the range ~5×103 n/s to ~104 n/s and followed the inverse law dependence with distance. Control experiments did not result in statistically significant neutron or ray emissions.
©2006 The American Physical Society
The only number here is the 10e4 neutron/sec. which should be interesting to anyone here. Without need for a PNS, it could be verified by anyone with a moderate budget.