Toroid size on Big Coils

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>

From what I see on the profesional coiling sites, in particular KVA 
effects, and Tesla Technology Research, the toroids seem small for 
the size of the larger coils. I know the cost of large spun toroids 
is prohibatively expensive. In the case of the M-13 magnifier, the 
majority of pics, show the discharges comming off the corona ring and 
not the toroid. With this coil, and Electrum, many of the arcs seem 
to be hitting the secondary. At the Cheesehead teslathon this past 
summer, the M-200 of D.C. Cox had several secondary strikes, one of 
which severely damaged the sec. He said 'that's what happens with too 
small of a toroid.  How does one avoid this kind of catastrophic 
damage? I'm planning to make a coil similar to DC's M-150. It uses an 
18" form, and I have a 36" spun toroid. I don't want to destroy my secondary.