Re: Gas & Gaps

To: tesla-at-pupman-dot-com
Subject: Re: Gas & Gaps
From: Terry Fritz <terryf-at-verinet-dot-com>
Date: Thu, 17 Sep 1998 22:10:53 -0600
Approved: terryf-at-verinet-dot-com
At 03:37 PM 9/17/98 -0600, you wrote:

>Original Poster: "Sam Barros" <sambarros-at-hotmail-dot-com> 
>
>>Electronegative gas, like SF6 (oxygen? chlorine?) has twice higher 
>standoff
>>voltage, but inert Ar & Xe quench faster
>
> Oxygen will be perfect for oxydising your gap! It will make your copper 
>electrodes turn into copper oxide over 5 times faster than before.
> The only use I see for clorine in a gap is if you want to make some 
>copper cloride and die from clorine poisoning... Clorine is VERY 
>reactive!

Aren't Helium-Neon laser and neon lamp electrodes silver chloride, because
then the metal recondenses back on the electrode, and greatly extends the
tubes life, similar to halogen bulbs?

One benificial effect of adding a little 'attachable' electro-negative gas
could be a hysterisis or schmidt trigger effect. The oxygen attaches to
stray electrons, increasing the breakdown voltage, and reducing the size and
resistance of the spark gap. When saturated and ready to breakdown, these
meta-stable molecules crash into other molecules, and release charges for a
more rapid avalanch than would happen otherwise. So adding a little oxygen
(or SF6 which won't burn metal) to the argon mix may help sharpen its curve,
making for a more rapid transition through its lossy, resistive phase.

I'm just guessing about this, plasma can do interesting things.

> If I was you I'd try Nitrogen or, better yet, HYDROGEN! Use some 
>pressure as well...
>

Yea, from what I've read, in such books as Gas Discharge Closing Switches by
Schaefer (excellent book, thanks Bert) that would be a good choice.

Hydrogen thyratrons use titanium as a hydrogen-releasing sponge, as hydrogen
diffuses into metal and glass over time, changing the tubes operating point.
But thyratrons operate on the left side of the 'Paschen' curve. So rather
than increasing breakdown over time, the sealed gap would decrease over time.

As the tube heats, that will also change the operating point. I like the
idea of a solid-state switching supply to charge the discharge cap, and
triggering the spark gap. And there so much smaller than 60Hz transformers.

Sorry about my incoherent post. I posted notes, rather than a more coherent
2nd draft, which I deleted of course.