Super Static Gaps

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Original poster: "James Zimmerschied" <zimtesla@xxxxxxx>

I have noticed that the spark gap is the heart of a disruptive Tesla coil. 
Using the same small coil, I have experimented with a number of different 
spark gap systems to try to see what the effect on spark output would be. 
Changing from a poor performing gap to a good design makes a significant 
improvement on spark length.

Rotary gaps have been identified as a gap system which is on the high end 
of performance. Experimenters like John Freau have shown that synchronous 
rotary gaps work better than asynchronous gaps for small coils. However, 
they are not that easy to build and are tricky to operate. Many beginners 
use the series cylinder gaps that were pioneered by Richard hull and 
others. While these simple gaps work, they will not give the best 
performance. I have tried vacuum gaps (sucker gaps) which also work pretty 
well and are easy to build but have found another design which should be 
considered.

I have recently performed some tests of a static gap design built by my 
friend Bob Svangren which I will refer to as a "super static gap". It 
consists of a stack of brass plates with a hole in each plate. A large 
brass washer is soldered on each side of the hole on each plate. The plates 
are stacked in a frame and foam rubber is used as a spacer at the corners 
of each plate so that a series gap is formed between the washers. A bolt 
with a plastic knob is mounted at the end of stack so that by adjusting the 
knob, the gap spacing is varied. The stack of plates is mounted to a 
chamber which has a vacuum cleaner motor and fan. The fan pressurizes the 
air in the center of the stack and forces air out between the washer faces. 
This provides the quenching of the arcs formed between the washers.

I have compared this gap design on a coil which is a 4 x 17 in using about 
1200 turns of #28 wire. A 30 ma NST is the power source. So far the super 
gap has outperformed static cylinder gaps (several configurations including 
a 9 gap unit with a vacuum fan), several types of sucker gaps, an 
asynchronous rotary, and a synchronous rotory gap. Not only are the 
streamers longer with the super static gap but there is breakout all over 
the toroid. In addition, I have been able to stack a 6",a 12" and a 16" 
toroid on the coil with spark length growing to 30". For reference, the 
synchronous rotary best has been 24".

What I have seen is that this type of static gap is very efficient at 
transferring power to the system. It is also very easy to use compared with 
rotary gaps. The quenching can be varied by adjusting the blower speed.

The Svangren design is easily adjustable. We have used an insulated 
extension to adjust the gap spacing while the coil is running to peak the 
system.

If anyone is interested, I can be contacted off the list for photos and 
sketches.
Jim Zimmerschied