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smooth sphere vs unsmooth sphere


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From:  Sulaiman Abdullah [SMTP:sulabd-at-hotmail-dot-com]
Sent:  Thursday, March 26, 1998 10:25 AM
To:  tesla-at-pupman-dot-com
Subject:  Re: smooth sphere vs unsmooth sphere

Tristan,
You can estimate the voltage produced by your coil now.
VOLTAGE = 2.83 MV x R         (R = radius in meters)
I just worked this formula out today based on a commonly accepted value 
of 25 micro-coulombs per square meter being the limit before breakout.

>From:  Mad Coiler [SMTP:tesla_coiler-at-hotmail-dot-com]
>Sent:  Wednesday, March 25, 1998 6:15 PM
>To:  tesla-at-pupman-dot-com
>Subject:  smooth sphere vs unsmooth sphere
>
>To all coilers,
>
>For the last few months I have been running my small 3" classic coil 
>with two metal salad bowls for the HV terminal. The salad bowls were 
>placed on top of each other as to make a sphere. This setup costs about 
>$2 and works great. For a long time I kept hearing how a smooth topload 
>will outperform one that has edges. So I borrowed a sphere from one of 
>those Van de Graph (I hope I didnt misspell that too bad) generators 
>that were just sitting in the phsysics lab without any insides in them. 
>The two different spheres were approximately the same radius. First 
>results: after tunning at lower power levels I turned the power up. It 
>seems the curvature wasnt enough for breakout on the smooth sphere and 
>instead arced from near the base of my sec coil to my pri coil. I then 
>placed a bump on the surface of the sphere by taking a small nut and 
>taping it to the surface with aluminum tape. I went over this a few 
>times with some more aluminum tape so it has no sharp edges and is 
>fairly smooth, protruding about 1/2 inch. I then ran the coil slowly up 
>to full power and it arced out from the bump and actualy rised off the 
>bump and traveled slightly up the side. Befor (with the salad bowls) 
>there was an edge all around the sphere and the arc would come out all 
>sides at once. Now most of the power is in one big branching arc. Arc 
>length increased from about 18" to 24". The pictures of mine on Chip's 
>site (www.pupman-dot-com) is of the salad bowl topload and the edge is 
>clearly visible with the arcs comming out all aoround. I probobly wont 
>have any better pictures for some time. And the performance increase 
>might even be more than is stated above because the primary tap is at 
my 
>last turn and might need more turns.
>
>Tristan Stewart
>
>
>
>