New spark gap idea.

From: 	Julian Green[SMTP:julian-at-glosilk.demon.co.uk]
Sent: 	Sunday, June 01, 1997 5:28 AM
To: 	tesla-at-pupman-dot-com
Subject: 	New spark gap idea.

Some time ago I recall a message on this list that suggested a
new idea for spark gap construction.

The idea was to use a spinning metal disk as an electrode of the
spark gap.   By spinning the disk at high speed the surrounding 
air would be forced to move at high speed near the surface of
the disk and thus aid quenching.

So I built it.   I used two pieces of aluminium tubing as 
stationary electrodes mounted 1mm above the spinning disk.  The
disk was insulated from the motor using fiber glass
board.  With my trusty 10,000 varible speed motor and varaic I 
connected the spark gap into the TC primary circuit.   With the
motor at full speed I powered the coil up to 50%.  With no balast 
in the supply I nearly smoked my variac.   I have no idea how much 
current was being drawn as the 20A ammeter read full scale.

The gap worked to some extent as the sparks in the gap had a 
definite pop to them with no degrade into an arc/flame.  The
electrodes remained cool.   The output of the coil was very hot
white sparks of short length, very powerfull, spark length was
disappointing only 10".

Perhaps I could have got more if I increased the spark gap width
and used more than 50% input voltage, but with a hot smelling 
variac I thought to finsh it there.

If you think this idea sounds promising then I am willing to have
another go.   Comments welcome.

Julian Green