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Re: spark gap
Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Tim,
You'll probably get various opinions based on our experiences. For a
120mA NST, an SRSG would be of benefit. However, for a static gap, I
prefer solid vs hollow myself. I've found hollow gaps heat very
quickly and require quite a lot of air to keep cool. One down side of
hollow gaps is tap connection (it's hollow). A solid rod stock gives
the added ability to tap a hole in the end of each electrode for
connections. I'm currently running a solid brass gap and can run it
indefinitely with air flow. With the same air flow on a copper hollow
gap, I couldn't. It took a little time, but eventually the sparks get
shorter and shorter over time as the gap heats up and lowers the
voltage required to arc the gap. Static gaps are very heat dependent
for arc voltage stability. Probably the #1 issue. The radius of
curvature does play a role but good gaps can be built with all the
sizes you've mentioned with a 120mA supply.
With that said, realize that hollow gaps have been the main focus for
years and is the majority of the lists experience with static gaps. I
guess mainly because of cost and easy access to copper tubing. Mass
is certainly helpful for heat dissipation and is even typical for
stationary electrodes on rotary gaps. The principal applies, however,
air is still required in either case and definitely required for
higher current gaps.
Take care,
Bart
Tesla list wrote:
Original poster: Timjroche@xxxxxxx
I'm running:
12kV 120mA NST
.03 uF 45kV maxwell tank cap
12 T .25" tube .25" spacing primary
4.343" OD 28awg 17" lng secondary
maj. dia 17" min dia 4" toriod
What is the best place to start a static gap? I have . 5" solid Cu
(12 pcs. 4" long), .5" tube, 7/8" tube, and 1.125" tube...is hollow
better? bigger dia?
What about length? my 7/8" (6 pcs. 6" long) better than .5" 3"long?
can you have to many gaps? i.e. total gap=.5", 2 tubes?, 6 tubes?, 12 tubes?
thanxs
Tim