For those who can't find surplus, the HV cables used for most modern Xray equipment, are insulated with EPR (Ethylene Propylene Rubber). Okonite Wire and Cable is one of the major suppliers. I am not sure, but GE may still be in the business. In the New England area, Dielectric Sciences Inc, just outside of Boston, manufactures custom HV cable and termination assemblies up to over 100 kV.
A typical 100 kV rated EPR cable is a little over 0.500" OD over the insulation. It has a thin semiconducting coating over both the conductor and over the insulation exterior, typically a braided shield and a silicone rubber or PVC jacket. It can usually be obtained with 1 to 4 conductors (for filament power in an Xray application).
Alden (in CT, I believe) also makes cables and connectors. With a product line that goes up to about 100kV.
I have used standard RG-8U cable with an LDPE insulation with good success at up to 80 kV, for hundreds of hrs. What is nice about this cable is that terminations are quite easy to do. Simply strip back the shield and plug it into a snug fitting hole in an insulating block (such as PE) with an inch or so of wall thickness and Presto!! A 50 kV or more termination and socket. About 6 - 8 inches clear length (more for higher voltages) will handle about 50 -60 kV.
Of course you can't use LDPE inside a Fusor, but up to the feedthrough and for connections to the HVPS, it works real well and it's quite inexpensive.
Dave Cooper
Created on Monday, February 19, 2001 1:30 AM EDT by David Cooper