NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/sci/physics/fusion/1789

Text File | 1992-07-23 | 6.4 KB | 120 lines

Newsgroups: sci.physics.fusion
Path: sparky!uunet!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!mrg!rpetsche
From: [e-mail] (Rolfe G. Petschek)
Subject: Re: Why Ying?
Message-ID: <[e-mail]>
Sender: [e-mail]
Nntp-Posting-Host: mrg.phys.cwru.edu
Reply-To: [e-mail] (Rolfe G. Petschek)
Organization: CWRU Physics Department
References: <[e-mail]>
Date: Thu, 23 Jul 92 15:09:42 GMT
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In article <[e-mail]> [e-mail] (Dieter Britz) writes:

>Something bothers me about the Ying experiment. I'm just a humble
>electrochemist, so maybe some physics expert out there can enlighten me:
>The Ying theory says, correctly, that one of the branches of d-d fusion is
>d + d --> (4)He + gamma (23.x MeV); this is in fact the controversial minor
>branch, with a probability of 1E-07 times the other two, with the infamous
>50:50 branching ratio, yielding neutrons or tritium. OK. Ying now proposes
>to enhance this minor branch by tickling it with gamma rays at just that
>energy, 23.x MeV.
>
>I understand that quantum physics is not like chemistry but I still can't
>shake the thought that this is the wrong way around. In chemistry, if you
>have a reaction like
>
>A + B + C + ... ---> O + P + Q + ...
>
>then if you add, to a mixture of all these, one of the products O, P, Q ...,
>you drive the reaction backwards. This is Le Chatelier's Principle, and we
>understand it today in terms of thermodynamics, equilibrium constants etc.

All correct.  However:

Think about a laser.  A laser has a population inversion (many more
atoms in an excited state than in a lower level state) and this can be
thought of as a system with a *negative* temperature.  Well
negative temperatures are hotter than any positive temperature so you
can convert heat (the energy in the excited state) at a negative
temperature into heat at a positive temperature or into work [you can
easily verify this from standard thermodynamical formulae - but be
careful the Kelvin statement of the second law only works at positive
temperatures while the Clausius statement works for any temperatures,
given that all negative temperatures are higher than all positive
temperatures {it is impossible for any engine working in a cycle to have
the sole effect of transfering heat from a colder reservoir to a hotter
reservoir}- really you should think about beta=1/T as the appropriate
variable].  Anyhow with all of this systems with a negative temperature
have weird-o properties and, in particular Le Chatelier's Principle
comes out dead backwards - again a fact you can verify by re-doing the
arguments which get you Le Chatelier's Principle at positive
temperatures.  Thus you shoot light into the active cavity
of a laser and more light comes out [provided there is a population
inversion (negative temperature) and some other conditions].

Well now lets think about d and He and suppose that they are ideal
gases [this won't matter much].  If the reaction you consider is in
equilibrium at any positive temperature then there is lots of He and
little d, because He has so much less energy.  To make there be more d,
as there is in the Ying experiment using the formula

c_d^2/c_{He} = lambda^{-3}exp(-Delta E/kT)

where c_d is the concentration of deuterium, c_{He} is the concentration
of Helium, lambda is a (ratio of) thermal wavelengths and I am ignoring
non-ideal gas effects, Delta E is the dd --> He energy change then you
readily find that T has to be negative.  Thus there is a clear
population inversion, (more d than needed at any positive temperature)
and a negative temperature in this system so that if you can tickle this
system appropriately you can stand Le Chatelier on his head.  This is
what Ying proposes.

>> Hmmm.  You have the average seperation of D2 to D2, no?  In a gas or even
>> in a liquid this is probably much greater than the 1.7 average for Pd:D.
>> The liquid D2 is lumpier, but on the average much more dilute, no?  Which
>> is the more important value, the average of the lumpiness, or the lumps?
>>
>> And, something I should know after all this time, but are the D's in the
>> Pd lattice mono or do they still hang around together?
>
>If I remember my numbers correctly, the d-d separation in D2 gas is 0.72 A,
>and in PdD it is about 4.2 A. This was one of the early "proofs" by physicists
>that cnf is impossible. It falls down on the possibility (accepted by some
>knowledgable people) that the PdD crystal environment has some special
>properties to enhance fusion rates. I wouldn't know. Are Schwinger and
>Hagelstein senile and non compos, respectively? We must not go by authority, it
>is said, but inevitably we do. Frank Close and Huizenga are authorities, too,
>and they flatly deny the possibility of such special solid state effects.

I have never understood and fo the Schwinger/Hagelstein papers and in
consequence do not believe them - however

>The question whether there is any D2 in PdD is a good one. In fact, there is
>no unity about just what form deuterium takes in the deuteride. Most people
>accept that it is in the form of rather highly mobile deuterons, i.e.
>positively charged deuterium nuclei; I did find at least one paper claiming
>that it is in fact negatively charged D- ions that predominate. I don't know.
>Metallurgists will tell you that at high loadings, when micro-voids form, some
>deuterium will evaporate off into these as D2 gas; this could be the way that
>super-0.8 loadings fit in. This is well known to metallurgists and corrosion
>people, because these small gas bubbles are under high pressure (not 10**27
>atm though) and do damage to the metal; it happens to important metals like
>steel, copper, etc. and is called hydrogen embrittlement.

and one supposes that if these pressure were high enough then fusion
might take place.  Now there is absolutely no need for pressures like
10**27 but there is need for pressures of many, many Megabars and this
is (a) impossible with a few volts of excess chemical potential and (b)
will rip the metal to shreds, anyway.  However this is an effect which
might make cold fusion many orders of magnitude faster in a cold fusion
system than in ordinary D2 gas.  Doesn't make it interesting,
unfortunately.
--
Rolfe G. Petschek            [e-mail]
Associate Professor of Physics        [e-mail]
Case Western Reserve University        [phone]
Cleveland Oh 44106-7079