Re: topload questions

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 1/24/03 2:37:29 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:


>No. Capacitance is almost purely a function of the geometry of the
>conducting surfaces, with negligible influence of the surface details.
>Actually, a single thin wire loop has great part of the capacitance of a
>solid toroid (or even a solid ball) with the same diameter.


Hi Antonio & all,
        I was intrigued by this statement and tried calculating the 
capacitance of a topload of 16" OD with chord diameters of 0.1" (wire) to 
8.0" (0" ID). The results are shown below: Note 16" is the outer diameter 
of the toroid, not the C-C diameter.

Chord ID Cap. % of Max
Diam           (pF)      Cap.
0.1 15.80 3.98 22.4%
0.2 15.60 5.58 31.4%
0.5 15.00 8.61 48.4%
1.0 14.00 11.68 65.6%
1.5 13.00 13.71 77.0%
2.0 12.00 15.14 85.1%
2.5 11.00 16.17 90.9%
3.0 10.00 16.90 94.9%
3.5 9.00 17.39 97.7%
4.0 8.00 17.67 99.3%
4.5 7.00 17.79 100.0%
4.6 6.80 17.80 100.0%
4.7 6.60 17.80 100.0%
4.8 6.40 17.80 100.0%
4.9 6.20 17.79 99.9%
5.0 6.00 17.77 99.8%
5.5 5.00 17.62 99.0%
6.0 4.00 17.36 97.5%
6.5 3.00 17.00 95.5%
7.0 2.00 16.56 93.0%
7.5 1.00 16.04 90.1%
8.0 0.00 15.45 86.8%

I guess the interpretation of the result depends upon the exact definition 
of "great part of the capacitance".
Matt D.