On Jan 6, 2006, at 5:38 PM, Stephen A. Lawrence wrote:
Thanks for the additional explanation and the reference to the 2002
paper.
I'll take the time to read what you've already said about this a
bit more carefully before I post any further comment <blush>
No need for blushing! This is not trivial stuff, at least for me.
In fact, Nyle Steiner refers to the conditioned electrode as the
cathode in <http://home.earthlink.net/~lenyr/borax.htm>:
Begin quote:
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"The aluminum becomes the cathode after a forming process of applying
some ac current through the rectifier. Often, many jars were used in
order to accomodate high voltages. It has been reported from various
sources, that these rectifiers would also emit a faint glow when in
operation.
While experimenting with these rectifiers, I have found them to work
quite well and I have been able to observe the glow. It was also easy
to make full wave rectifiers using more than one rectifier in
traditional full wave rectifier circuits.
A rectifier can be easily made by mixing borax or baking soda into a
pint jar of water and inserting an aluminum strip and a strip of
another metal. After a forming process of running ac current between
the two electrodes, the aluminum electrode becomes the cathode and
the other electrode becomes the anode.
It seems that aluminum is necessary for the cathode, but the anode
can be just about anything that conducts electricity. The aluminum
cathode can be a 3/8" wide strip cut from an aluminum pie plate. The
anode can be lead, carbon, steel or stainless steel. Copper tends to
make a bluish green mess and does not seem as desireable. I have
found most types of anode materials to work the same but the
differences may be a long term effect not easily observed in the
course of my experiments."
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end quote.
This is utterly confusing when the objective is to obtain the blue-
green glow and *not to build or describe a rectifier*. When a cell
with a conditioned electrode (e.g. aluminum or nickel) and a neutral
electrode (e.g. platinum) is operating as a diode and is in the
maximum current direction, i.e. the "forward" direction, the
conditioned electrode is indeed the cathode, from an electrochemical
point of view.
However, if the objective is to drive the cell with DC current in
order to condition an electrode or to produce the blue-green glow,
then it is the *anode* that is the electrode where this happens.
This is fully consistent with the notion that the glow occurs during
reverse bias of the diode cell.
Below is the report of the experiment where I first discovered the
glow was occurring on electrodes operating as anodes, and where I was
very careful to check the diode polarity and to conduct control
experiment to rule out the added HV diodes as being part of the
effect. At the time I was unaware that glow on electrolytic rectifier
plates was commonly known, or even that they existed for that matter.
I was doing electrospark experiments, so even distinguishing the glow
regime from the electrospark regime in the AC experiments was a
pretty exciting event. The DC experiment was quite a surprise. As
you might be able to tell from the report, I had doubts about the
polarity. It just was not what I expected.
Begin report by H Heffner
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Experiment Report 11/7/97
Added water to electrolyte to compensate for evaporation.
"Warmed up" cell by running at about 100 mA (variac at 10 then up to
to 20 %) for about 5 minutes. Glow clearly visible in dark but noise
not yet started.
Put some dummy diode pairs (P1 and P2) rated at 15kV Peak V, 100 mA,
into circuit like so:
P1 and P2 both look like:
-----|>|-------
| |
---|<|----
Circuit:
--------V1----T1--A1---P1------o
|| ||
--------V1----T1-------P2------o
V1 - variac
T1 - HV transformer
A1 - mA meter
Pi - dummy diode pairs
Continued to run as before about 5 minutes. Both electrode glowed as
before. This verifies that 2 pairs of these particular type of
diodes work OK in circuit.
Tried geiger counter within about 1" of electrodes. Got no increased
counts.
Switched off variac when current was at 70 mA, leaving voltage
setting alone.
Then inserted full bridge B1 made of same type of diodes:
Circuit:
--------V1----T1--A1----B1------o +
|| || ||
--------V1----T1--------B1------o -
V1 - variac
T1 - HV transformer
A1 - mA meter
B1 - full rectifier bridge
Switched on variac and noted:
(1) only one electrode lit, the other was totally dark
(2) it was not nearly as bright as before
(3) noticeably more gas evolved at the dark electrode when DC used
(4) same current (about 70 mA).
(5) unexpectedly, it was the anode that lit.
(6) the full surface of the anode lit, as before
Swapped + and - leads and the other electrode lit. Glow went with
the + pole.
Just to check my understanding, the diodes are marked with a stripe
at the end:
P N
-------|>|-------
stripe at this end of diode
indicates diode cathode
i -----> conventional current moves this way
<--- e- electrons move this way only
- end + end
If circuit is like below then electrode marked + is anode of cell:
--------V1----T1--A1----|>|-----o +
|| ||
--------V1----T1--------|<|-----o -
It is the anode of the cell, the electrode closest to the bar on the
diode that glows.
This indicates that the glow is oxygen related and not hydrogen
related. It likely is oxidation reaction of Al. That is a very
bright reaction, so that makes some sense.
The reduced brightness indicates that maybe hydrogen plays a role in
adding heat to the reaction? Or maybe the H2 is necessary to produce
full bubble collapse along with massive heat of recombination focused
in sonoluminescent bubbles?
Could it be that some other electrode metals glow also, but in
invisible parts of spectrum. If so, they should still produce the
noise, the cavitation, provided the oxide is an insulator.
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end 11/7/97 report by H Heffner.
Horace Heffner
