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Re: [Phys-l] current vector



A source of X-band horns I intend to contact for purchase, if inexpensive, advertise theirs as being aluminized
ABS (sewer pipe plastic -- Acrylonitrile-Butadiene-Styrene trimer)

bc

John Denker wrote:

Edmiston, Mike wrote:

Speaking of current density distributed across the cross-section of the
wire... What is "current thought" on what this distribution looks like.
I was under the impression that the density is higher near the surface
of the wire, and at some potentials and at some frequencies the current
is mostly on the surface.

I also know that when I was at Los Alamos and I crossed paths a couple
times with HV-power-transission guys, they treated the current as if it
were on the surface and they were testing hollow conductors.


For sure at high frequencies, the current is strongly concentrated
at the surface. This is the usual "skin depth" calculation.

A lot of microwave plumbing is gold-plated. Indeed some of it
is gold-plated brass, or gold-plated steel ... and it could be
gold-plated plastic and work just as well, because the skin
depth is so small that the waves never make it past the plated
layer.

=============

At DC the story is different; the so-called magnetic pinch tends
to drive the current somewhat toward the middle.

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