Re: Wire for a magnifier driver

> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Wire for a magnifier driver
> Date: Wednesday, January 13, 1999 6:27 AM
> Original Poster: NickandSim-at-aol-dot-com 
> To Jim,
>            coax is only ok to 6.5kV and thats the really thick 10mm

Depends on the kind of coax... For instance, the RG-8 family (roughly 1/2
inch in diameter, 10 mm), is rated at 5000 VRMS. However its breakdown
voltage, is actually quite a bit higher. Some things to think about..

1) The spec is a guaranteed spec, in use, where the VSWR might not be 1:1
and there could be substantially more voltage at standing wave nodes.

2) You can calculate a much higher breakdown based on the polyethylene
dielectric and the field strength equations for coaxial tubes.

3) I and others have run RG-8 at 40-50 kV DC without breakdowns. Your
mileage may vary.... Watch out for sharp bends and warm temperatures which
can cause the center conductor to drift out of the center, greatly reducing
the dielectric strength.

Also, for winding a coil, the voltage between turns is much less than the
total voltage across the entire coil.. In the case of a 1 MV Tesla Coil
secondary with 500 turns, the voltage between turns is only 2 kV.