From: ames!FNALD.FNAL.GOV!DROEGE
Subject: Status #5 Cell 4A3
Reply-To: ames!FNALD.FNAL.GOV!DROEGE
Organization: Sci.physics.fusion/Mail Gateway
Date: Wed, 30 Dec 1992 20:59:37 GMT

Status #5 Cell 4A3                   

We have now run cell 4A3 for 184 hours (yesterday's post said about 200 but 
that was not looking at the log book).  For the last 60 hours or so the 
calorimeter has been in balance at 7.250 watts with an rms balance noise of 
0.006 watts rms using the one hour average data.  Using the one minute data, 
the rms value of the variation is 0.025 watts.  To noise experts, this 
probably tells all, but not to me.  

In any case, since 60 hours is long compared to the primary calorimeter time 
constant of 1/4 hour, we think this is the true calorimeter balance point and 
the calibration taken as 7.788 watts has just changed for some reason 
(probably the large changes in temperature have changed the gain of the 
thermoelectric devices).

We will now sit here until we see something or give up.

Gas continues to increase in the motor driven syringe, indicating evolved 
Oxygen from absorbed Deuterium until we learn better.  Presently we have 
accumulated 170.4 cc for a 2.69/1 D/Pd ratio.  I just report what I measure 
and how I do it folks, I make no claims about it being right.  You may 
remember earlier I reported that we were over 200 cc for over 3/1 ratio, but 
various experiments to try to verify the loading caused a loss of loading - 
but with some assurance that the measurements are correct.  The structure of 
the gas absorption looks just like the experiments that I have done on the 
bench with open cells where the gas can be seen to be boiling out of the Pd 
cathode during discharge conditions, and when there are just no bubbles at the 
cathode during absorption.  

>From time to time there are also the little time constant bumps where it looks 
like the cell suddenly gets hot.  However, since this is the observation of 
noise, I can also find spots where it looks like the cathode suddenly gets 
cold with a time constant.  I believe the positive pulses prevail, and 
remember analysis of previous runs does show an asymmetry in the delta 
temperature distribution.

Because of the problems with this run, we are re-designing the Mark III.  The 
plan is to put a conduction calorimeter (like the device used by Appleby) 
inside of our null balance calorimeter.  Then we will run the null balance 
calorimeter at a constant 0 C, and warm up the experiment to the desired 
temperature inside the constant 0 C environment.  We already know by 
experiment that this will make the null balance calorimeter quieter, so 
everything should get better.  By having two calorimeters making the same 
measurement, we can check one against the other.  While the conduction 
calorimeter will be less accurate, we should still be able to do 0.1% on the 
cross check.  To those wondering why it takes so long to get it right, 
remember that the Wheatstone bridge was not a very precise device for a long 
time.  Even in the 1950's long after bridges were in use, I did some work on 
precision resistor stability at NADC Johnsville.  Over a several year 
measurement program the precision wire wound resistors we were testing would 
wander around 0.1% or so.  So I do not feel so bad, even with a 7% change.  I 
just have to learn how to do it right.  There is plenty of indication of long
periods of stability.  I just have to learn what can cause a change. 

Tom Droege

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