Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>
[snip]
> >and it seems that sphere protects the secondary worse than toroid:
> >http://www.lod.org/Projects/electrum/testing/pages/electrumeric.html
>
> You're correct -- a toroidal electrode would have provided far
> better field control than the spherical electrode used on
> Electrum. The spherical electrode geometry was part of the overall
> aesthetic requirement however, and had to be accommodated. As a
> result, the operating instructions for the machine specify to
> immediately remove power for 5 seconds if a tower strike is observed.
>
>So far, there has been no permanent surface tracking observed in
>Electrum's outer casing.
according to this photo:
http://www.lod.org/Projects/electrum/testing/images/electrum40kW3.jpg
does the secondary outer surfaces in touch with the sphere? but my
toroid would be mounted higher on the secondary top, then, as Antonio
said there wouldn`t be any problems:
"Reduction due to surface tracking would apply if an insulating surface
were in contact with areas of the terminal where the electric field is
high, but this doesn't happen in this case."
> Based on experience, 5kV/inch seems to be a reasonable surface
> gradient to maintain on the outside of a secondary form.
200kv/m it is in straight way, and if it would be like that:
http://www.lod.org/Status/90L10KPhotos.htm
maybe this value would be more? for example Conner`s 30" secondary
flashes at about 600kv.