From: ames!FNALD.FNAL.GOV!DROEGE
Subject: How it works
Reply-To: ames!FNALD.FNAL.GOV!DROEGE
Organization: Sci.physics.fusion/Mail Gateway
Date: Thu, 1 Oct 1992 20:31:48 GMT

I note that Dieter Britz has to periodically put up a note on how to get stuff 
from his bibliography.  Since the followers of this group change, this will 
answer several current questions about how my machine works.

The calorimeter is a true null balance device, like a Wheatstome bridge.  As 
far as I know, the only thing like it for heat.  I consciously did not patent 
it, and the designs are published in ACCF1 and ICCF2 proceedings, so I believe
the design concept to be in the public domain for all to use.  I am not an 
altruist, I just did not see a market.  

A two liter dewar is fitted with a large puck shaped plug of aluminum in its 
mouth.  The idea is that any heat coming out of the dewar must pass through 
the puck and so develop a uniform gradient.  The puck is connected to a copper 
plate by two arrays of thermoelectric devices (TED).  One array (378 
junctions) operates in the Peltier (current through a junction moves heat from 
one junction to the other) mode and is driven by a constant current source.  
The second array (93 junctions) operates in the Seabeck (temperature 
difference produces a voltage) mode and measures the temperature difference 
between the puck and the plate.  A third very large set (762 junctions) 
operates in the Peltier mode and is servoed to control the temperature of the 
plate.  One face of this set contacts the plate, and the other face contacts a 
water cooled base plate.  We use multiple devices in a symmetrical arrangement 
for each of these sets to assure a uniform distribution of the thermal 
gradients. 

Several different sized TED are used.  The large ones are about an inch square 
and an tenth inch thick.  They contain 63 junction pairs.  They are made from 
Bismuth Telluride semiconductor like material.  The crystalline chunks of 
material are soldered between two ceramic plates so that the junction pairs 
are electrically in series but in thermal parallel.  One amp and 10 volts will 
pump about 30 watts between the two faces if they are at the same temperature.  
One of these junction pairs puts out about three times the voltage of one of 
the better thermocouple combinations.  So one of the big devices is a 
wonderful device to measure the temperature difference between two flat 
plates.  This is the "DD" that I sent Jed Rothwell.  From memory, I think 
about 15 millivolts per degree C temperature difference for the 63 junction 
pair device, and it goes right through zero - to no more than a microvolt - so 
such a device can measure a temperature difference of 1/15000 degree C with 
microvolt stability electronics.  It is also very low impedance and thus low 
noise.   

The way we operate the calorimeter is to drive the large set between the puck 
and the plate with a constant current source.  This driver uses temperature 
controlled shunts and temperature controlled electronics to assure that it is 
constant.  We estimate it is good to at least 1 part in 100,000.  We do not 
have anything good enough to (Only a 6 digit Keithley microvoltmeter/ammeter) 
say for sure.  We then drive the big set between the plate and the water 
cooled base to hold the temperature between the puck and the plate to zero as 
measured by the small puck-plate set.  A third servo drives a heater inside 
the dewar to hold whatever temperature is set for the experiment.  Under these 
conditions, the puck - plate set is driven at constant current.  The puck and 
the plate are at the same temperature - we successfully hold to a millidegree 
rms with an operating (and thus noise producing) experiment.  The puck and the 
plate are at constant temperature.  We claim, and have many calibration 
experiments to prove it, that under these conditions the puck plate set 
removes a constant amount of heat from the calorimeter.  At the present 
operating point this is 10.151 watts.  

Because of the large radiation losses from the dewar (in school I was taught 
that you never had to consider the radiation losses from a dewar as other 
losses were much higher), it is covered with 1 1/2" of foam, then an aluminum 
shell then 1 1/2" more of foam.  The shell is connected to another set of 
TED which are air cooled and which hold the shell to the same temperature as 
the inside of the dewar.  This "large" radiation loss is of order 0.010 watts 
per degree C.  So it is well worth operating this servo in this experiment. 

Leads going into the calorimeter are brought through the puck plate interface.  
They pass through a long copper tube connected to the plate, and so any heat 
that they carry is given up to the plate, which is servo driven and can thus 
stand the heat load.  Their potential is measured as they pas through the puck 
plate interface.  This makes sure that lead loss inside the calorimeter is 
included in the energy computation correctly.  It does make a difference.  We 
compute a voltage current product for each lead going into the calorimeter and 
add up the powers in a Kirchoff sense.  Every lead has a shunt on it which 
makes a redundant current measurement.  We can thus add up all the currents 
and demand that they sum to zero.  We worry a lot that we sample the voltages 
and currents correctly.  In general, we sample much more often than the 
bandwith of the measured variable.

We measure "anomalous heat" when the E*I products of the calorimeter leads 
add up to less than the refrigerator constant determined by experiment.  

The calorimeter has an internal thermal capacity of 2500 joules per degree C.  
It can thus soak up a large thermal transient without error.  We could stand 
a 25,000 joule pulse.  The largest seen so far is about 300 joules.  The 
inside of the calorimeter simply gets hotter, and the plate and the shell 
servo follow to hold radiation losses to zero.  Gradually the heater servo 
backs off and the value of a heat impulse can be measured by the integral of 
the reduced heater power input over time. 

We always operate with a closed system and so do not have to be concerned 
about the electrolyte "boiling away".  There is a catalyst in the cell.  Any 
net gas unbalance is measured by a servo driven syringe which holds the cell 
pressure to ambient with great accuracy - usually less than 0.1" H2O. 

There is more information in the two "cold Fusion " proceedings papers.  I 
have a longer version of the second paper for real fans.

Tom Droege