Re: Static Gap question.

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

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi Luke,

Tesla list wrote:

>Original poster: "Luke" <Bluu-at-cox-dot-net>
>I have looked around at the types of static gaps and have a couple 
>thoughts of my own.
>But let me see if I get this right.
>
>Assumptions.
>The versions using the copper pipes in parallel to on another work well 
>because they allow lots of surface area for the gap to cool thus quenching 
>it rapidly?

The pipe is a good for heat dissipation with air-flow and it's easy to get 
and use at the local hardware store (the latter probably being the #1 
reason). I can't comment on the quenching (I feel quenching is more 
assumption than measurement. Not the actual quenching, but the cause).

>Question 1.
>If the gap is cooled off sufficiently and the gap is quenched well say by 
>large amounts of air is there any other benefit to using a larger surface 
>area for the spark gap?

The benefit is more control over the arc voltage (is it stable or does it 
fluctuate). Both the radius of curvature and temperature stability are two 
key ingredients for control. Surface imperfections should also be kept at a 
minimum. Note that with pipes, there is always one point on the pipe where 
the arc occurs, and often it can be at the far ends where the edge is. I 
like to round my ends down to prevent this.

>And question 2.
>The JavaTC program estimation of the arc distance in relation to potential 
>is based on the surfaces of the spark gap being curved like as in large 
>dia. balls or pipes in parallel. This assumes the distance between 
>electrodes is not greater than the diameter of the electrodes.
>
>Would the same approximate distances be obtained for said voltage if flat 
>electrodes were used parallel to one another? Say like two 1” dia. discs 
>separated by ½”. Would that have a breakdown voltage close to the 
>breakdown voltage of two 1” dia. copper pipes in parallel to one another?

Actually, North in his chapter 7 paper describes how if the radius of 
curvature is large and the separation is much smaller, the electrodes 
appear as planar (like your two discs proposed). He also used an analogy of 
a person standing on the earth where the radius of curvature appears flat, 
and does give a good idea of how this occurs. But note, as you get into 
your spaceship and travel at say 2 or 3 times the distance of the earths 
radius, the curvature becomes very apparent.

I think the breakdown can be set up so that a ball electrode or disc 
electrodes have very near the same arc voltage (mathematically), but with 
the disc comes the edges, so there is an area for probable arcing. I think 
realistically, imperfections with surface features and the parallel setup 
would probably tend to move the arc voltage value from the best guess, but 
I don't know how much.

Take care,
Bart




>Thanx
>
>Luke Galyan
>Bluu-at-cox-dot-net
>
>
>
>
>