[600MRG] looking for a corona expert....

[Larry Molitor]

A short bit of unexpectedly good WX co-incident with some unexpected free time allowed me to drop the broken 630m vertical this afternoon. This was very fortunate because with the one top hat/guy line dangling, the antenna was in danger of being totally destroyed in the next wind storm!
A quick inspection showed considerable corona action had occurred on the end insulators during the recent freezing fog/rain events. I hope to do a complete evaluation and post a short paper on my web site eventually but for now I will just say it appears necessary to implement corona discharge mitigation.
My question regards corona ring size. Pat, W5HTH, has made some helpful suggestions and the info on W5JGV's web pages is interesting. Also google searches on corona has produced a lot of HV transmission line info. Unfortunately nothing has turned up that would let me calculate optimum ring size/shape.
Due to mechanical considerations I will be limited to a conductor diameter equal to #12 or #10 wire. I can make the ring as large as 8 inches diameter. With these limitations would it be better to use a smaller or larger diameter ring? I.E. would a 4" ring be as good or possibly even better than an 8" ring, or vice versa. 
I'm not going to have the time or the energy to do this more than once so I need to get it right the first time. Any help would be appreciated.
Thanks & 73,
Larry - W7IUV / WH2XGP