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RE: [TCML] Q,,question
The proximity effect I think plays into this issue. The ID of a tube has the current affected by the 360º surface more so than the OD. I don't think 100% of the ID skin effect is discounted, but it is not equal to the skin effect on the OD. Is this true?
Terry
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of Chris Swinson
Sent: Wednesday, December 05, 2007 10:53 AM
To: Tesla Coil Mailing List
Subject: 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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>
>
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