NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/physics/fusion/3104

Text File | 1992-12-28 | 5.8 KB | 100 lines

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Path: sparky!uunet!zaphod.mps.ohio-state.edu!saimiri.primate.wisc.edu!ames!pacbell.com!tandem!zorch!fusion
From: ames!FNALD.FNAL.GOV!DROEGE
Subject: Christmas News
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Sender: [e-mail] (Scott Hazen Mueller)
Reply-To: ames!FNALD.FNAL.GOV!DROEGE
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Date: Mon, 28 Dec 1992 20:59:46 GMT
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SANTA BRINGS JOULES FOR CHRISTMAS (We are having them appraised.)

In keeping with Christmas tradition in the Droege household, we began to see
"anomalous heat" on Christmas evening.  After pushing the current up as far as
it would go without causing gas unloading (350 ma per sq cm), we turned on the
temperature ramp and started up towards 60 C from 4 C (The cell thermometer
actually read 12 C at this point, but the calorimeter "insides" was at 4 C.)

At the same time, the current ramp was turned on to ramp up to 500 ma per sq
cm while the temperature was increasing.  The idea of all this was to push
harder to hold the little D's in the Palladium lattice as they got hotter and
wanted to get out.  After 8 hours we were up to 60 C and an indicated D/Pd of
1.57.  The balance point was 7.131 watts compared to a calibration of 7.788
+/- .035 watts taken over most of the month of December at this operating
point.

This indicates that we have an "anomalous heat" of 0.657 watts in a
calorimeter which we believe was very conservatively rated with a one sigma
0.035 error by several months of calibration.  This would be 6.57 watts per cc
of Palladium as the cathode is 0.1 cc..  We have also measured D/Pd loading of
as high as 3.

I don't believe either and neither should you.

Of the two, I have more faith in the loading.  At one point, the gas loading
had stabilized at 112.2 cc of evolved gas at a current density of 500 ma per
sq cm.  If this is oxygen, then 224.4 cc of D2 had been absorbed into the 0.1
cc Palladium cathode.  If I am computing things right this is a D/Pd ratio of
1.77.  In an experiment to check the loading, the current was then backed down
to 50 ma per sq cm.  37.5 cc of gas disappeared from the system over a 12
minute period.  About one cc could be attributed due to the temperature change
in the cell.  This would mean that 73 cc of D2 gas evolved from the cathode
amounting to 0.57 D/Pd, and this is far from the condition that would evolve
it all.  We are making appropriate temperature corrections on the gas volume.
Barometric corrections are too small to be significant, but we do worry about
unusual weather conditions.  The rest of the change is apparently a real
evolution of gas from the cathode, and was confirmed by the catalyst first
getting hotter due to the increased gas evolution load, then getting colder
due to the lower long term gas load.

One possibility is that the catalyst changes in efficiency with load.  It
could make sense that a richer mixture is required at high current density
that at low, and thus excess gas builds up in the cell volume.  But this is
hard to accept as higher currents make the catalyst hotter, where we believe
it is even more efficient.  It is also hard to imagine that such a condition
would be stable.  The gas loading will sometimes be steady for many hours in
a row.  There is the further problem that we have different indicated loadings
i.e 150 cc and 200 cc under exactly the same conditions of temperature and
current.  The cell gas volume is only 50 cc so this would require that the
increase in D2-O2 gas mixture completely fill the cell.  I thus think that the
gas measurement is a real absorption somewhere.  It will be very interesting
to see if all the gas is evolved (i.e. enough D comes back out to eat up the
accumulated Oxygen) at the end of the run.

The apparent excess heat is a different problem.  I think it is just a change
in calorimeter zero.  This because it just came up and sat there.  I will need
heat that comes and goes for belief.  After it is run the required 30 days or
so, I will reverse the cell and run it at the same power level reversed.  We
shall then see what zero it finds.

This brings up a point of contention with Jed Rothwell.  We both see runs by
Takahashi, Mills, Nagoya and others that seem to show excess heat.  I keep
doing very long calibration experiments that would appear to show a very
stable apparatus.  Depending on whether I run at fixed room temperature with
the shell servo on or at variable temperature with it off I get calibration
runs with stability of 1 mw or 35 mw.  But from time to time, there are
changes in calibration that I cannot explain.  These seem to always come
during an experiment and have always been in the direction of "anomalous
heat".  Why don't I believe that these are true "anomalous heat" events?
Because they do not match my profile of what an event should look like.

While I struggle and struggle and still sometimes have 10% jumps in my
measurements, I see very little detail of the calorimetry (except McKubre) of
those that claim heat.  What I do see does not impress me.  Since I have
problems and am using relatively sophisticated apparatus, it is hard to
believe that the others making quite casual measurements do not have them too.
There is also the possibility that all those measurements just get in the way,
and it is better to just use a simple temperature bath, a dewar, and a
thermometer as done by P&F.  But I don't think so!

While there are a number of checks built into this calorimeter design, there
are not enough.  The next generation calorimeter will have a conduction
calorimeter built inside the null balance calorimeter.  This is sort of the
design now, but the conduction measurement is not good enough to check the
null balance calorimeter calibration to the required accuracy.

Tom Droege