Re: Brush spark gaps

>From: Bob Schumann <tesla-at-america-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Brush spark gaps
>I recently bought some huge carbon brushes
>at ane electronic surplus store. They have
>a flat surface of about 3" X 2".
>I was wondering if it is feasable to employ
>these as a spark gap. It seems to me that
>the surface could take a 'hit' very well.
>Bob Schumann
	Based on the refractory properties of carbon, at first look,
carbon looks promising. Unfortunately, carbon takes a very long time
to deionize. Several seconds if memory serves me.  

A carbon arc will restrike after power has been shut off for ~2
seconds without having to touch the electrodes together again. This
will foil any attempt to quench your spark gap. 

I might be fun to see if a negative resistance oscillator could be set
up using the carbon arc as an active element. Has any one tried this?

Ed Harris may have corrections to this, I'm still learning about arcs
and glow discharges. (an arc may not have the same negative resistance
properties as a glow discharge)