According to Ignoramus29428 said:
I finally picked up the caps from Fermilab. Each of them weighs about
40 lbs and they look nice, very cute color also.
So... I would like to make some sort of a pulse discharge thingy from
readily available materials. Can crushing would be my first choice.
My plan is as follows, to use copper pipe as conductor. I bought some
HV diode stack (4 7.5 kV diodes) and a HV probe.
The first thing to make would be a reliable system for discharging the
caps safely, and test it at low voltages. I would probably want to use
two 12 MEG Victoreen resistors in series a permanently attached
bleeder.
With four 1 uF caps, RC would be 2*12,000,000 * 4/1000000 = 96, which
is hopefully acceptable, and power dissipation in the resistors will
be about 3W per resistor.
Hmm ... I remember a high voltage test cage which I used to have
to calibrate at a place which made high-voltage rectifiers (among other
semiconductors) was set up in a metal electronics rack with a door of
1/2" Plexiglas. The door was held closed by a long screw cut with a
buttress thread (lots of slope on the side towards the free end, and
almost vertical on the side towards the knob which turned it. The
female thread was a hole in two plates with a spring wire between them
pinching on either side of the screw.
To close it -- all you had to do was push.
To *open* it, you had to spend a couple of minutes turning the
knob to unscrew the screw -- and about halfway during the time a cam
would swing a safety grounding bar into contact with the high voltage
terminals, to make *sure* that there was no high voltage there when the
operator reached in to change the device under test.
My main questions concern the spark gap. How to practically make a
decent spark gap, and also how to safely trigger it.
For instance, would 3/4" brass balls such as McMaster item 9617K47, be
adequate? If not, I have 3/16" tungsten electrodes. Would they make an
adequate spark gap?
The larger the radius, the shorter the gap will need to be,
because charge concentrates on small radius points. I've got no idea
whether the TIG electrodes could handle that much power (but I'm not sure
how many caps you intend to hook in parallel for this.)
If not, can I use sections of, say, 1" copper pipe, placed at some
distance with their axes perpendicular?
Also, what is the best way ot safely triggering a spark gap. My
understanding is that there is a rule of one inch per 15 kV. Would
making the gap 1.5" and injecting some argon into it be a safe
and effective triggering method?
Does argon have a lower dielectric constant or breakdown voltage
than air? I would expect it to be somewhat more insulation than air.
I think that you'll have to inject a very high voltage pulse
between the two with the electrode closer to the ground side, but
capable of ionizing the air to make the gap enough shorter to dump
everything from the caps -- with something like a flash lamp trigger
transformer. (Hmm -- perhaps a spark coil from a car?) Part of the
problem is keeping the trigger transformer from being a consumable.
Perhaps set the gap small enough so at near your full voltage it
will break over on its own, and simply set it up and then start
charging, letting it trigger itself -- though you won't know exactly
when.
Perhaps UV illumination will ionize the air enough to trigger
the gap.
I am going to do a lot more reading and I will post my "design" here
and get it to pass some consensus before implementing it.
A good idea -- this strikes me as a very dangerous experiment.
(But possibly fun.
There is no way I would generate that much of an EMP near all of
my computers.
Enjoy,
DoN.