Re: On sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 3/30/01 2:40:33 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> John (& all)-
>  
>  No, the spark length is markedly less emanating from a sharp point, as is
>  the max. of the E-field, of course. 

Ken,

I must have remembered incorrectly from the past.  I had thought
that in some previous work, you had said that the spark lengths were
the same for the large toroid, small ball, and point.  If I now 
understand correctly, the sparks were the same length from either
a small ball, or large toroid, for short or long durations, but the
breakout sharp point always gives shorter sparks.  So it seems
that some sort of radius larger than the end-of-spark radius is 
needed for longest spark results, but there seems to be a very large range
of radii (from small ball to large toroid), which give the same
spark length.  If this is correct, then I wonder just how small the
ball can be, and still obtain the same spark length?

>  Also, the amplitude of the
>  following-on E-field is unchanged, toroid-spark vs. sharp-point-spark. 
>  This holds true for either the ~400 us duration or the ~7 ms.  That's all
>  understandable: it's the effective emission radii in the several cases
>  that control the situation.  That's especially clear in regard to the
>  E-field after spark initiation being the same: the emission radius in all
>  such cases, regardless of the radius of the initiating metal surface, is
>  the "radius" of the end(s) of the spark--very, very small!

Yes, I understand the spark end radius is very small.... indeed like a point,
and this lets the voltage plummet vs. a large radius condition.

John

>  
>  Ken Herrick