Tantalizing Sparks

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Original poster: "Marry Krutsch by way of Terry Fritz <twftesla-at-qwest-dot-net>" <u236-at-earthlink-dot-net>

Hi everyone!

	With the recent posts concerning sparkgaps, I thought I might post some
results, and pose a few questions.

	I just got my fourth 4500v 300mA copier xfmr last week, and quickly put
it, along with my others into a large plastic box to make a 13kV 250 mA
supply.  I re-sized my MMC to 0.044uF, re-tuned, hooked up the supply
(ballasted to 1.5 KVA), and hit the switch.  Sparks were dissapointing,
only 4 feet, even after careful tuning.  Not satisfied, I removed the
ballast, and hit the power once again.  Things were different this time,
with 6 foot thick arcs coming from my breakout point.  I got excited,
then realized that 6 foot sparks with 4 KVA isn't very good (Shouldn't I
get 7 or 8 feet?  More??).  The first fraction of a second at the
beginning of each run was the best, then the SG power arcs with a
vengance.  Opening the gap didn't help too much.  I openned it to almost
3/8", but power arcing continued.

	I was wondering if I should put a non air-blown static gap in series
with my existing vacuum gap.  I'm trying to find a motor to make a SRSG,
but it may be a while.

	I noticed that even though the gap has a large vacuum blower on it, the
arcs seem to envelope the outer portion of the gap.  They should start
at the gap between tubes, then be sucked inward by the passing air, but
run on the surface of the tubing instead, jumping the gap in the
process.  (If the ASCII drawing doesn't survive the perilous trip to the
list, forgive me.)

     Arcs here	     and here
________________    _______
----------------    -------
			   |
   <----Air flow	   |
			   |
________________    _______|
----------------    -------

	According to my math, the coil was processing 7 joules per bang (before
power arcing), and strangely had no hints of the racing sparks I know
and love so much.  Anyone know why?

	In case anyone cares, I used 4 xfmrs, in anti parallel (2 on each side
of ground), so it APPEARS that it is safe to do this with these
transformers.  I used no protection network, only a safety gap (never
fired).

	Also, would a 30,000 rpm ARSG be worth building?  I have the motor (my
current vacuum blower), and was wondering if anyone had any input.

Thanks,
Winston K.