Re: Static Gap Stains

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Static Gap Stains
From: Richard Quick <richard.quick-at-slug-dot-org>
Date: Mon, 21 Oct 1996 00:17:00 GMT
Quoting Bob Schumann <tesla-at-america-dot-com>:

 > I built the cylindrical static gap (Richard Quick type)
 > and have a question if anybody else has seen this happen to
 > their gap. I followed Richard's instructions almost to a tee
 > but I could never bring myself to permanently glue the copper
 > electrodes in place. I have access to a polishing wheel that
 > puts a mirror shine on them. When it is time to clean the gap,
 > I remove all the electrodes and polish them. I have to go
 > through the re-gap and alignment routine each time but I just
 > can't get myself to touch sandpaper to them. Anyway...with
 > the electrodes out, I notice vertical brown stains on the      
 > green SDR35 PVC innerwall between where every electrode        
 > (gap) was.

 > Even though I have not scrubbed at the PVC because the stains
 > are harmless, they will not merely wipe off.
 > I am just curious what does this. Is it the x-rays or UV from
 > the spark possisbly that affects the PVC? Such as the PVC
 > gets a 'sunburn'? Of course this is of no operating            
 > consequence as the gap works as well as ever, I just wondered  
 > what did it.

Sublimed copper. This deposit should be cleaned off at the same 
time that the electrodes are serviced. Excessive buildup of
sublimed copper creates a semiconductive ring around the top of
the electrodes which can trigger the formation of an arc. Once an
arc leaps across the surface of the plastic, the resulting carbon
track ruins the gap housing.

I have access to a glass bead blasting cabinet. I just pop the
gap in and clean everything up. The beads clean off oxidation
from the electrodes and removes deposited copper at the same
time.

Richard Quick


... If all else fails... Throw another megavolt across it!
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