Coil hiccupping w/o breakout point

To: tesla-at-pupman-dot-com
Subject: Coil hiccupping w/o breakout point
From: "Mark Broker" <broker-at-uwplatt.edu> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 04 May 2000 21:23:57 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hello, all

Last night I set up my 1350VA coil outside the enginerring hall to fiddle,
impress, and juts plain have fun.  My setup consists of 3 15/30s, a 120BPS
SRSG, a .042uF (LTR) MMC, 10"ID pancake primary, a 6.25"OD x 29.5" WL
secondary with a 5x17" and a 6x24" toroids (larger on top).

When I set it up and fired it, I got "normal" streamers, which lasted for
about 2 seconds.  Then, the coil would stop producing arcs/streamers, but
the gap would still be arcing (seemed like there was a bad connection,
which I checked for several times).  The MOVs on my NST filter got very
hot, even though I only ran this condition for a few seconds while I played
with the variac knobs.  At first I thought that maybe my ground was really
crappy (a standard aluminum "street" light).  But I never got a shock off
it when I touched it while this was happening (meaning no charge buildup).

So, after waiting for the MOVs to cool off, I checked all my connections
again (perfectly fine, as far as I can tell).   Then, I threw a bare 14AWG
wire over the top toroid to act as a breakout point (one end was resting
inside the toroids, one stuck out about 4 inches from the OD of the larger
toroid).  Using this breakout point, I was able to gt 55" white-hot arcs to
a grounded rod for periods of about 90seconds with no problems (a little
short of John's equation, but there's a lot of steel and iron beneath the
primary).

During initial testing, I was using only 2 of the NSTs and was able to get
decent breakouts without using a wire.  As I recall, I usually had two or
more simultaneous arcs usuallty coming from the taped joints of the
aluminum dryer duct.

Does anyone have any ideas to explain this interesting behavior?

Thanks in advance

Mark B