Re: Energy Discharge - Foil Test Characteristics

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <teslalist-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Hi Dan,

I remember seeing a test like this on Eimac's site which discussed power 
supply crowbar protection for high power vacuum tubes:

"As a test for the amount of energy delivered in an arc, Eimac suggests 
that the power supply used be short-circuit tested by causing an arc (in 
air) from a short lead connected to the tube terminal to the surface of a 
grounded sheet of 0.025mm (0.001 in.) thick aluminum foil. If total energy 
delivered is less than four Joules, the hole burned in the foil will be no 
greater than 3mm (0.120 in.) diameter.

An alternative test which will verify tube protection is to short-circuit 
test the power supply through a 6-inch length of 0.079 mm diameter (#40 
AWG) soft copper wire. If total energy delivered is less than four Joules 
the wire will remain intact. This test must be run at full operating 
voltage and may be performed by using a vacuum switch or other suitable 
high voltage relay to apply a short to the supply through the aluminum foil 
or the copper wire." See:
http://www.cpii-dot-com/eimac/ab17.htm

Hope this helps...

-- Bert --
-- 
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Tesla list wrote:
>Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><dhmccauley-at-spacecatlighting-dot-com>
>A common method of determining discharge energy is performing what is called
>a "foil test."  Basically, a thin sheet of aluminum foil or similar is taped
>across a surface which is then charged up to a high potential and then
>discharged.  The size of the hole in the aluminum foil can then be measured
>and the resulting energy in joules and/or current can be determined through
>the discharge path.
>How uncommon are the methods to calculate the actual energy discharge using
>the size of the hole and thickness of aluminum (or other material).
>Anyone have any additional information regarding this test?
>Thanks
>The Captain
>
>.