Re: Natural RF suppression?

To: tesla-at-pupman-dot-com
Subject: Re: Natural RF suppression?
From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Thu, 29 Oct 1998 16:41:24 -0700
Approved: terryf-at-verinet-dot-com

Hi Bart,

> Original Poster: "Barton B. Anderson" <mopar-at-uswest-dot-net> 
> 
> Gary,
> 
> Tesla List wrote:
> 
> > Original Poster: Gary Lau  28-Oct-1998 0735 <lau-at-hdecad.ENET.dec-dot-com>
> >
> > >Original Poster: "Barton B. Anderson" <mopar-at-uswest-dot-net>=20
> > >
> > >Could you elaborate more how you constructed the aluminum standoffs in
> > >between each copper pipe? I was discussing with someone today an idea
> > >of using aluminum components in a sparkgap. Not to conduct energy, but to
> > >utilize aluminum's RF suppression characteristic to enhance quenching.
> >
> > What RF suppression characteristic?  Are you saying different metals
> > favor conduction at different frequencies?  I don't think so.
> >
> > Gary Lau
> > Waltham, MA USA
> 
> I'm saying the conductance changes at RF frequencies for aluminum. I have
> heard this on this list. I don't know how dramatic the change is. At first
> thought, I was relating this to the resistive oxidation which aluminum
> develops, but posts indicated it is at the RF frequencies which aluminum's
> conductive ability drops, and this tells me that it is not the resistive
> oxidation, but the actual characteristic of aluminum at high frequencies. I
> don't know why, and it may or may not be true, but if it is true, then could
> this variable be used somehow.
> Bart

It's resistivity is higher than that of copper and therefore skin 
depth is increases more as frequency decreases. 

Cheers,
Malcolm