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Re: Holy Crap! WOW, that's the origin of quarter-shrinking!
Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
We gave it a try tonight. Due to time and equipment we were only able
to really fire once at 5400V at 60e-6 Farad. It made a big orange
flash but no real fireball yet. The chalk tube blew apart but not
terribly violently or loud. We were at 875 joules and the water seems
to take most of the "bang" out of it.
A strong small ceramic tube could probably survive the shock. We were
thinking a ceramic standoff could have the glazing ground off for it.
The tube is probably very well sealed at the bottom but still allowed
to fill with water. The top of the tube is probably just at the
surface of the water. McMaster or Ohmega might have unglazed tubes too.
The magnitude of the flash seemed about what one would expect. If it
were 7X more, that would probably be about right to match the
pictures and movie of the real one.
So we seemed real close but did not have it quite right yet. The cap
bank could go up to 18kJ if it had too in the future.
One real problem is the SISG. If fired perfectly "once" but I never
stopped to think what 800+ joules might do to it. All the IGBTs are
shorted. Seems 100X its pulse rating is "too high". Easy to fix, but
that leaves us with no reliable switch for the fireball thing...
Don't know how to solve that yet.
Bill's info here is very interesting ;-) But for now, we had to use
what we had on short notice.
At 07:06 PM 6/11/2006, you wrote:
I totally forgot about this stuff! I tried the ball-lightning
water-plasma test at the Dale Travous workshop around 1991 and it didn't
work. Lots of bang, but no light. In hindsight I guess our circuit
resistance was way too low, so the capacitor dumped all its energy into
the water in microseconds rather than in tens of mS. Amazing damage
I hope those physics people credit the discoverer of that water-plasma
smoke ring effect, Dr. P. Graneau. I think the key article was in the
Tesla conference stuff from 1984.
Separate topic: Go read
Early Quarter-shrinker history (Bert Hickman)
But there was another bit of information.
It started when Dale Travous, builder of a large Seattle TC in 1990,
wanted one of those big thick hardbound books from the mid-1980s Tesla
conferences in Colorado. So did I, so we put our money together and
bought a couple. One of the articles was very cool: making "ball
lightning" by discharging a huge capacitor through about 1 cc of water,
with the water in the bottom of a fluted-shape horn made of machinable
ceramic. The vaporized water was supposed to eject as a glowing smoke
ring of plasma. The article was by Dr. Peter Graneu, the railgun physics
At about the same time, Dale found some huge capacitors at Boeing Surplus.
They were useless for a coil primary, being many KV but several uF. But
they were just right for that water-vaporization Ball Lightning
experiment, so he started messing with them. The capacitors were at
Dale's lab/studio off Denny and Terry Ave., and he spent some days getting
to the point of charging and discharging them without getting killed.
(the contact switch was a small piece of welding rod, 20ft of 1/4" tygon
hose, and a mouth to blow the air to eject the rod.)
He found that the discharge current could easily shatter #10 solid copper
house wiring. I told him about a "can crusher" article I'd seen many
years before, so he tried smashing some copper water pipe. Then he
started smashing pennies ...then quarters!
So the "plasma toroid ball lightning" experiment caused the invention of
We finally tried Dr. Graneau's BL experiment. (This happened over 10
years ago, but I think I recall all the details accurately.) For my
horn-shaped cup I took a 2" wide cylinder of white polyethelene and used a
lathe to carve a trumpet-shaped concavity in the end, maybe 1/2" deep and
2" wide. Then used a ?3/4in? drill to make a small water-chamber in the
base of the horn-shaped hollow. The electrodes were ?#14? solid copper
wire, threaded through holes drilled in the side of the cylinder and
coming into the base of the hollow. I was worried that the discharge
might crack the PE and throw pieces around, so I wrapped the outside with
many layers of black electrical tape. Yet the entire top was open, the
water was not enclosed at all. The whole thing was about 3x smaller than
the device shown in Graneau's article. It was also PE, not machinable
We fired the capacitor while hiding behind 19" racks. BAWOOM, no flash of
plasma, then a sound like rain.
The polyethelene cylinder had vanished. It turned into particles about
the size of aquarium-gravel that rained down all over the lab. There was
one chunk left hanging on the electrode wire, with little bits of black
tape clinging. The black electrical tape "spalled off" and turned into
All this was essentially caused by a large droplet of water laying against
a platic block!
Not having any insulators which could survive those forces, and not
knowing why no plasma appeared, I gave up and started playing with other
But that team of Germans clearly found a trick: immerse your tiny
discharge-container under water. ANy acoustic shock won't sit inside the
walls of the little tube and cause it to explode, instead they will
radiate out into the water bucket as sound waves.
Also, the resistance and inductance of our setup was way too high. If
anyone manages to duplicate their setup, but finds that the small tube
gets shattered ...add some heavy coils as inductors/resistors to widen the
current pulse. See photos : http://amasci.com/amateur/capexpt.html
(((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))
William J. Beaty http://staff.washington.edu/wbeaty/
beaty@xxxxxxxxxxxxxxxxxxx Research Engineer
billb@xxxxxxxxxx UW Chem Dept, Bagley Hall RM74
206-543-6195 Box 351700, Seattle, WA 98195-1700