Re: Rotary gap gaps, LDPE vs. HDPE

To: tesla-at-pupman-dot-com
Subject: Re: Rotary gap gaps, LDPE vs. HDPE
From: Richard Hull <hullr-at-whitlock-dot-com>
Date: Tue, 17 Sep 1996 10:28:04 -0700
Tesla List wrote:
> 
> >From chip-at-poodle.pupman-dot-comSun Sep 15 21:44:09 1996
> Date: Sun, 15 Sep 1996 21:37:49 -0600 (MDT)
> From: Chip Atkinson <chip-at-poodle.pupman-dot-com>
> To: Tesla List <tesla-at-poodle.pupman-dot-com>
> Subject: Rotary gap gaps, LDPE vs. HDPE
> 
> Greetings,
> 
> Of those of you who have a rotary gap, what is the _greatest_ distance
> between the stationary electrodes and the rotating electrodes?  I'm
> asking because I am about at the decision point in the construction of my
> rotary gap.
> 
> >>>
>  BTW, as long as were talking about LDPE, is there much of a difference
> (for cap use) between LDPE and HDPE ? Are their properties about the
> same ?
> <<<
> 
> One property that is definitely NOT the same is its pliability.  Your
> hands will have to be quite a bit bigger and stronger to roll a cap with
> HDPE.
> 
> Chip


Chip, All


There is no maximum separation!  I run a very microscopic separation 
.020"!  This is very dangerous unless your rotary is very stable and has 
very fine machining.  I would imagine that .060" to .200 would be the 
norm depending on what you wanted from the system.  Close separation 
allows for series quencher gaps.  Too wide and opening forces all your 
energy to be dissapated in the electrodes of the rotary and can actually 
cause flaming.  It is a matter of trial and error.  You should always 
make the electrodes so that they can be varied of a fairly wide range.

There is a slight difference in breakdown voltage of the polyethylenes. 
(HDPE is better)  The increased cost and difficulty of rolling HDPE is a 
factor that must be considered.  Note*  Be real careful with all 
polyethelene.  If you are using 60mil and a 5mil scatch is accidently 
gouged in it, you now have the entire sheet weakened to 55 mill!

Richard Hull, TCBOR