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Re: [TCML] Q,,question

Is this not assuming a solid wire ? current would be pushed to the surface yes. but AFAIK it is not the same for hollow tubes which have two surfaces.
Skin effect should work on both sides of copper tube or flat ribbon. I do not see why current would pass on a flat strips both sides but not both sides of a copper tube.
I see it as 2 surface areas, 100khz will be about 0.1mm depth so if the tube is 0.5mm thick then it should be 0.1mm outside and inside the tube, the rest of the copper mass of 0.3mm is now the core and not used...
I looked up skin effect, it just says "the surface" but there are two surfaces. So I do not see why it would favour only 1 side of a tube ?
If you split open copper tube the surface area would still be the same. So does not see why it matters what shape it is.. Maybe you know of a website which states more arruratly what skin effect is. There is a lot of sites though it only says "the surface".... 

Chris
----- Original Message ----- From: "Lau, Gary" <Gary.Lau@xxxxxx> 
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, December 05, 2007 3:56 PM
Subject: RE: [TCML] Q,,question
The inside surface of a tube carries no HF AC current, due to skin effect. However, if you split the tube open into a ribbon, now both inside and outside surfaces are current-carrying surfaces, although the current density may not be uniform. 

Regards, Gary Lau
MA. USA


-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Chris Swinson
Sent: Wednesday, December 05, 2007 10:36 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Q,,question

David, Gary, J,

The inside of the tube still passes current just as much as the outside
does. If you cut it length ways like you say, where does the sudden mass of 
extra surface area come from ?
It sounds like you think the inside is not used, its all conducting flat or 
round. Splitting it open does not increase the surface area... Like Gary
said, it would give sharp rough edges and voltage will spark off the rough
edges. copper tube is smooth and round and works very well.  I agree also
that copper tube would be better from a corona point of view and over all
easier.
Only good way is to just use larger dia tube if you want to increase surface 
area without progressing to a flat strip...

Chris



----- Original Message -----
From: "David Rieben" <drieben@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, December 05, 2007 2:43 PM
Subject: Re: [TCML] Q,,question


Hi Chris, Gary,

I'm going to have to respectfully disagree with you here, Chris. If
you were to split a length of copper tubing length-wise, then you
would effective double the surface area, since the previously
unexposed inside of the tubing will now be exposed. However,
as Gary has stated, you would also add other losses that would
more than negate whatever gains that you obtained by doubling the
primary coil's effective surface area. And I would hate to even think
about TRYING to NEATLY slit a 50 ft. section of copper tubing
into a nice smooth ribbon ;^(/ I'm with Gary, I would prefer copper
tubing/pipe to copper ribon anyway as I find it much easier to work.

David Rieben

-------------- Original message --------------
From: "Chris Swinson" <list@xxxxxxxxxxxxxxxxxxxxxxxxx>

>
> ----- Original Message -----
> From:
> To: "Tesla Coil Mailing List"
> Sent: Wednesday, December 05, 2007 6:29 AM
> Subject: Re: [TCML] Q,,question
>
>
> Sirs,
> Would it be better to split a roll of 7/8" copper coil, and roll it
> flat?
> Seems more area would mean more "skin depth area"???
> Regards
> j.
> .
>
> The surface area will still be the same.
>
> Chris
>
>
>
>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla

You may realize some gain with the larger surface area, but I would expect
losses to increase even more because of eddy current losses. You would also 
increase losses due to corona off of the sharper edges.
And more significantly, how on earth would you do that, and not have it look 
like a mess?  You can find copper ribbon on eBay, but even so, I would
choose
tubing over ribbon.

Regards, Gary Lau
MA, USA
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