Current in conductors

To: tesla-at-pupman-dot-com
Subject: Current in conductors
From: Richard Hull <hullr-at-whitlock-dot-com>
Date: Mon, 22 Jul 1996 12:43:39 -0700

All,

There has been a bit of interest in details on RF current flow in 
conductors.  Ed Harris supplied the equation and his calculations came 
out to about .2-.3mm penetration at 100khz in copper.  I have always 
tripled this for a safety factor.  Thus, my post for 1mm penetration at 
100khz.  Current streamlines always follow the path of least inductance. 
Therefore, in a coil, about 80% of the current flows on the inner portion 
of the turns only!  Design all systems with this in mind!  This is why I 
use much large diameter tubing than the calculation say.  This is also 
why Tesla noted that thin sheet metal banding was the best primary 
material.  One learns these lessons fast with exploding wire and water 
arc explosion experiments where 50,000 amp RF Currents are the norm.

Richard Hull, TCBOR