After monitoring this topic several times over and seeing the
different
takes on Aluminum wire vs copper wire here is my take if anyone is
interested. Skin effect is the phenomenon where the apparent
resistance of a
wire increases as the frequency increases. At DC, the charge
carriers have
an even distribution throughout the area of the wire. However, as the
frequency increases, the magnetic field near the center of the wire
increases the local reactance. The charge carriers subsequently move
towards
the edge of the wire, decreasing the effective area and increasing the
apparent resistance.
Now it is true that resistance of a wire will increase as the
frequency
increases as I have just stated and as both DC, and Gary have each
stated,
however at frequencies below 1Mhz the resistances run pretty much
parallel
with each other, above 1 MHz the apparent resistances no longer run
parallel
and they begin to separate and the Aluminum resistance curve begins
a much
steeper climb than the copper curve. Although I have never run
experiments
on this phenomenon with real tesla coil use, I do understand where
each
person DC and Gary are coming with their perspective biases on this
issue.
Unless the tesla coils are going too be pulsed at 1 MHz or higher I
do not
believe it is really going to make that big a difference for the
common
coiler such as myself and many others on the list. It is true that
Aluminum
wire has a higher resistance per unit diameter and length as
compared to
copper, and if the diameter of the Aluminum is increased to match
the copper
DC resistance per unit length, I cannot really see any reason why
Aluminum
cannot be used as long you do not pulse it higher than 1 MHz it
should work
fine. For those that are using Micro SIm or some other simulation
package
this can easily be modeled and the effects can clearly be seen by
doing a
parametric sweep from say 60Hz up a GHz if one wants and you will
see the
real separation between the curves starts at around 1 MHz. I have
modeled
this before and that is where I am getting my information and if any
one
wants the model specifications I can give them to you and then it
can be run
by anyone using any of a sim packages out there.
The only reason I would not want to use Aluminum as compared to
copper is
due to the anodization that rapidly develops on aluminum and I am
sure even
that can be dealt with. But anyway that is my take on this mystical
topic
--Brian
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla