Aluminum vs Copper Primaries

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Harvey Norris <harvich-at-yahoo-dot-com> 

We normally think that since Aluminum has a higher
resistivity, that more losses might be involved in
using an aluminum primary vs that of a copper one. I
get about a half ohm for 100 ft of this 1/2 inch
diameter aluminum cable I am using.

The chart at
http://hot-streamer-dot-com/temp/skindepth.gif
shows that copper is 1.7 micro-ohm/ cm
(I assume that is supposed to be micro-ohm/cm^2 to
express area)
and that aluminum is 3.02 micro-ohm/cm^2
which would be a value showing that Al has 77% more
resistance then equal volumes of Cu

But when we compare the skin depth at 200,000 hz we
find that copper has about .06 inch vs aluminum at .08
inch, so Al has 33% more penetration from the currents
at high freq then does copper.

In viewing the trade-off here should we then think,
that given a sufficiently wide circumference of the
primary itself as a cross section, that aluminum is
actually only about 44% more less efficient for high
frequency conduction currents then copper?

This also raises the question of  what is the % of
time periods involved when the primary is actually in
high frequency vs the time when it is in source
frequency conduction. Isnt the high frequency time
period small compared to when the source frequency
currents are acting? This would mean that aluminum
would appear closer to 77% more resistance.

These are probably irrevalent issues, but I am
wondering since I constructed a primary using wider
circumference aluminum power cable, designated as 3/0
gauge about 1/2 inch in diameter, but it is also
stranded with about 18 strands distributed in the
grouping. Will the skin effect still take place on
each of these strands, even though they are adjacent
to each other with their surface areas coming into
contact?

Finally is the primary resistance not something to be
concerned about, since the losses involved in the
actual primary arc gap would be far greater then the
losses involved on the lines themselves?

Sincerely HDN