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#1
April 26th 04, 07:17 AM
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Applications of Hafnium isomer reactors?
Kelly McDonald writes:
I've been hearing a lot about them in the past few week. There seems to be talk about using them in suveilance drones, (Such as the current edition of Popular Mechanics) As first glance they seem to have a number of ideal properties for space applications. Low mass, high energy density, stable, energy release is highly controllable. Only in press releases, since no one else has been able to replicate the alleged effect, and there are strong theoretical reasons to believe that the alleged effect cannot possibly exist; this strongly suggesting that, very much like "cold fusion," it was an example of "pathological science," i.e., the claimants either screwed up, or are deluding themselves. Also, even if it _did_ work as claimed (which I =VERY= strongly doubt!) note that the alleged energy would be released as _gamma rays_, which are arguably the second most USELESS and IMPRACTICAL form of energy conceivable! (About the only thing that could possibly be worse would be neutrinos!) -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;' 
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#2
April 27th 04, 11:32 AM
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Applications of Hafnium isomer reactors?
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#4
May 2nd 04, 01:42 AM
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Applications of Hafnium isomer reactors?
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#5
May 5th 04, 02:09 AM
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Applications of Hafnium isomer reactors?
(Karl Hallowell) writes:
(Gordon D. Pusch) wrote in message ... snip Only in press releases, since no one else has been able to replicate the alleged effect, and there are strong theoretical reasons to believe that the alleged effect cannot possibly exist; this strongly suggesting that, very much like "cold fusion," it was an example of "pathological science," i.e., the claimants either screwed up, or are deluding themselves. Also, even if it _did_ work as claimed (which I =VERY= strongly doubt!) note that the alleged energy would be released as _gamma rays_, which are arguably the second most USELESS and IMPRACTICAL form of energy conceivable! (About the only thing that could possibly be worse would be neutrinos!) Actually, neutrons are further down on the impractical list than gamma rays. Part of the reason breakeven fusion is so hard to achieve - the fusion reaction keeps losing energy through neutron emission. You are confused on a number of points. First, neutrons are _MUCH_ easier to absorb than gamma rays, since they feel the strong force, and many nuclei have quite large neutron absorption cross sections. Second, the primary energy-loss mechanisms from a fusion plasma are bremsstrahlung radiation and synchrotron radiation, which are both fancy terms for "X-rays." These X-rays are emitted simply because the plasma is very, very hot, and rapidly cool off the plasma. By contrast, the plasma does not emit significant amounts of neutrons unless it is hot enough that a significant rate of fusion reactions are occuring. Third, the reasons why "Breakeven" has been hard to achieve are that: A.) Magnetically confined plasmas are very unstable and difficult to confine (someone once compared it to being "like trying to hold jello in a cage made of rubber bands); B.) It has been difficult to pump heat energy into the plasma faster than bremsstrahlung and synchrotron radiation carry it away. The combination of plasma instabilities and bremsstrahlung losses has meant that so we have not been able to keep a plasma dense enough and hot enough for long enough that it will "ignite." Fourth, fusion reactions do not "lose energy" through neutron emission; rather, when a deuterium and a tritium nucleus fuse, their _reaction products_ are a 3.5 MeV alpha particle and a 14.1 MeV neutron. In an "ignited" plasma, the alphas will provide more than enough heat energy to keep the reaction going, while the neutrons, being uncharged, will zip right through the magnetic field to be absorbed in the reactor's shielding blanket, where they will produce heat for conversion into useful energy, while simultaneously breeding new tritium fuel. -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'
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#6
May 5th 04, 02:59 AM
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Applications of Hafnium isomer reactors?
Gordon D. Pusch wrote:
First, neutrons are _MUCH_ easier to absorb than gamma rays, since they feel the strong force, and many nuclei have quite large neutron absorption cross sections. This is not a general truth. Many gamma rays are very efficiently absorbed by photoelectric absorption, with absorption lengths the nuclear scattering length in the same high-Z material. The photon absorption cross section in lead, for example, climbs very rapidly for photon energies less than 500 KeV Paul
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#7
May 5th 04, 04:14 AM
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Applications of Hafnium isomer reactors?
(Christopher M. Jones) writes:
(Gordon D. Pusch) wrote in message ... Very funny. O.K., I revise my statement to read that gamma-rays are about the most useless _NON-FICTIONAL_ source of energy conceivable, short of neutrinos! What about axions? *sigh* O.K., gamma-rays are about the most useless non-fictional, _NON-HYPOTHETICAL_ source of energy conceivable, short of neutrinos! (BTW, at least axions, =IF= they exist, _do_ couple weakly to the electromagnetic force, and can be stimulated to decay into photons when passing through a plasma or a strong electromagnetic field, so there is a minuscule chance that, unlike neutrinos, one might be able to do _something_ with them! :-T) -- Gordon D. Pusch perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'
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#8
May 7th 04, 01:12 AM
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Applications of Hafnium isomer reactors?
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#9
May 10th 04, 09:23 PM
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Applications of Hafnium isomer reactors?
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