Re: Huge Cap Possibility

[Terry Fritz <twftesla-at-uswest-dot-net>]

Hi Jim,

At 08:38 PM 10/8/2000 -0400, you wrote:
>One of my clients makes a product by laminating aluminum foil and
>plastic together.
>It is used as the shielding for network cabling.
>I realize that they use mylar which would not be good for Tesla use, but 
>we could spec any material.
>
>The resultant product comes off in "Mill Rolls". the laminate wound on
>large rolls approx 4 ft in diameter by 5 foot long and a nice tight
>wind.  When I look at these things I see a huge capacitor.
>
>Questions:
>
>If we were to make a capacitor by this method,
>what would the materials be (polyethylene?)

The highest grade polypropylene.  Everything else will tend to have much
higher loss and burn up.

>what would the thickness of the materials have to be?

A very good question.  Cap manufactures can pump 5kV/mil but we are lucky
to get 1/10th that in homemade caps.  Your may be better off using a series
of lower voltage sections, like all the pros do, to limit internal ionization.

> I assume the construction would be foil,film,foil

Probably.  Unfortunately, self healing caps are probably out of our reach
in this case.

>what kind of capacitance would it have and what type of power?  

That depends on many things but could be figured out relatively easily.

>How would we best terminate the connections

The ends of the roll would have all the metal layers protruding so they
could all be connected for maximum current flow and lowest loss.

>How big of a coil could it power (Avalon guys, I'm thinking of you here)

BIG!

>
>I would assume the whole assembly would be immersed in oil and
>evacuated.

You would draw out the air, back fill with oil that had a low air/water
content, and then reintroduce nitrogen to restore the pressure and collapse
any remaining tiny bubbles.  Sometimes craft paper is used to get the oil
to wick into the layers.  It is best to leave the center hollow to help
reduce heat in the center of the roll. (Oops!  Hope that was nobody's trade
secret ;-))  Vibration or ultrasonics can be used to help drive out bubbles
too.

>
>Does this sound plausible?

It can be done, but don't think for a moment that it will be at all easy!
Before starting, be sure you just can't go out and buy it for less money...

Cheers,

	Terry

>
><< Jim >>
>
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>Jim DeLillo
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