A new cap failure mode?

To: tesla-at-pupman-dot-com
Subject: A new cap failure mode?
From: Terry Fritz <twf-at-verinet-dot-com>
Date: Thu, 04 Feb 1999 20:18:16 -0700
Approved: twf-at-verinet-dot-com

Hi All,

	In an off list discussion, a topic came up that I have not seen before but
I always assumed may be a factor in capacitor failure.  

	When one places a nice safety gap across a capacitor, and it is firing for
any reason, what is the current in the discharge pulse?  Since Tesla caps
are designed to be very low inductance and low resistance, there is very
little limiting the current when the safety gap fires.  If a cap is charged
to say 20kV and the resistance of the mess is say 0.5 ohm - we get 40000
amps!!  That is enough to do some real internal damage to any capacitor.
The suggestion comes up that perhaps a safety gap placed directly across a
primary cap needs a little resistance in the circuit to keep this current
to a "safe" level.  

Comments or suggestions are welcome...

	Terry