Toroid Behavior

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

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

Hi All,

With Antonio's new field mapping tool, I have been able to perform some 
paper experiments to get a better feel for what parameters of the toroid 
affect what.  I have done three experiments all centered around a 6x24 inch 
toroid (since this is what I'm planning for my next coil).  Three results 
are given for each experiment:  Vbreakout (Vbo), Ctop, and Reach.  All of 
these were determined with the toroid hanging in free space with nothing 
else attached (like a secondary).  Reach was an attempt to determine how 
far the field "reaches" out to help with streamer formation.  I used 
Antonio's probe capabilites to measure the field at a distance from the 
toroid surface (horizontally) and found the distance where the field was 
1/10 (arbitrarily chosen for comparison purposes) of the value at the 
toroid surface.  The potential of the surface was set to Vbo for this 
purpose so the reach distance is the distance horizontally away from the 
surface where the E field dropped to 300,000 V/m.  The surface field 
strength would be 3,000,000 V/m

Experiment #1: Vary major diameter with minor set to 6 inches

size       Vbo      Ctop        Reach
------------------------------------------------
6x18   430KV   20.6pf   12.2inches
6x20   455KV   22.5pf   12.9inches
6x22   478KV   24.4pf   13.6inches
6x24   501KV   26.3pf   14.2inches
6x26   522KV   28.1pf   15.0inches
6x28   542KV   30.0pf   15.5inches
6x30   562KV   31.8pf   16.0inches


Experiment #2:  vary minor diameter with major set to 24 inches

size       Vbo      Ctop        Reach
------------------------------------------------
3x24   358KV   24.1pf   10.0inches
4x24   412KV   24.9pf   11.6inches
5x24   460KV   25.6pf   13.0inches
6x24   501KV   26.3pf   14.2inches
7x24   540KV   26.9pf   15.3inches
8x24   579KV   27.5pf   16.3inches
9x24   606KV   28.0pf   17.2inches


Experiment #3:  vary both minor and major diameters maintaining constant Vbo

size       Vbo      Ctop        Reach
------------------------------------------------
5x29   506KV   30.2pf   14.2inches
5x28   498KV   29.3pf   14.1inches
6x24   501KV   26.3pf   14.2inches
7x21   502KV   24.1pf   14.3inches
8x19   505KV   22.7pf   14.4inches


Most of us knows that major diameter mostly affects capacitance and minor 
diameter mostly affects breakout voltage, but the results of experiments #1 
and #2 show to what degree major diameter affects breakout and minor 
diameter affects capacitance.

The results of experiment #3 suggests that reach is mostly a function of 
breakout voltage.

Comments welcomed

Gerry R
Ft Collins, CO