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Argon Gap - First Light....
Hi All,
I finally hooked up my argon gap to my coil tonight with the following
results:
1. The gaps fired at a lower voltage than I expected. All the gaps fired
at about 9 to 10 kV. I believe this is due to the design of the gap array.
I failed to realize that at these high voltages, the capacitance from the
different levels of gaps would be significant. There are rows of gaps
separated by 1/4 inch glass plates. I now calculate the capacitance from a
lower to upper gap pipe at about 6.3pF. At 10kV those parasitic caps would
store around 300mJ each. Probably not a terrible problem alone but it
caused the next problem.
2. Micro arcing. In order the charge all the pipe capacitances up, tiny
micro arcs occur. These are tiny low power arcs that jump between the gaps
and serve to charge the parasitic capacitances. Unfortunately these arcs
make the gap's firing voltage lower than expected and make the firing
voltage somewhat unstable.
3. The powerful fan easily cools the 5 inch pipe sections. The chamber
grows somewhat warm but most of the heat is from the 85 watt fan. I am
confident that the chamber can run high powers without overheating. The
glass sides dissipate the heat to the outside very well.
4. The argon protects the gaps from burning and charring as expected. The
gap surfaces get a dull but clean copper coating.
5. The quench was excellent!! I moved my coil down to the lowest position
(k=0.20) and had a field probe monitoring the coil. At no time did I see
anything other than first notch quenching! This coil has never operated
with K high than 0.17 without quench failure. This is especially
significant since breakout could be prevented with the lower firing
voltages. There are three things that may have contributed to this:
a. The argon gas.
b. The air flow through the gaps.
c. The micro arcing.
The argon may have been the reason due to perhaps the clean firing or some
other factor. The air flow really shouldn't have been good enough to cause
the great quenching. The micro arcing effect very possibly could have been
helping the gap to open and stay open. It would have required the high
frequencies to charge all the little caps up to continue firing. perhaps
this "load" is enough to add a powerful quenching effect. If true, this
would be very significant since such an effect can be easily controlled and
applied to a number of other gap designs. Ideally the capacitance could be
raised but the micro arcing could be prevented or at least minimized.
There are three new pictures at:
www.peakpeak-dot-com/~terryf/tesla/experiments/argap/
argap050.jpg - The gap setup on the coil.
argap051.jpg - A typical scope picture. Top trace - secondary voltage
100kV/div. Bottom trace - Primary cap voltage 5kV/div.
argap052-jpg - A micro arc as picked up by the field antenna and primary
cap probe. Top trace - 20kV/div. Bottome trace 10kV/div. This picture may
or may not be accurate??
I still have more to do to track some of these questions down. But this
is what I know at this time.
Terry Fritz