RE: [TCML] Q,,question

["Lau, Gary" <Gary.Lau@xxxxxx>]

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
> >
> >
> >
> >
> > _______________________________________________
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>
> 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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