RE: [TCML] Acrylic Covers

[William Noble <william_b_noble@xxxxxxx>]

some of the info below just can't be true - in particular, whatever dielectric effect adding material around the coil has is not dependent on the existance of an airgap - the effect may be insignificant, but if you do the math, you will see that for these situations the existance of a gap doesn't matter.  What is true is that if there is an air gap, you can have all the normal effects of air taking place in that gap.
 
> Date: Thu, 22 Apr 2010 09:01:26 -0500
> Subject: Re: [TCML] Acrylic Covers
> From: pslawinski@xxxxxxxxx
> To: tesla@xxxxxxxxxx
> 
> On Thu, Apr 22, 2010 at 08:40, Brandon Garretson <garretsontech@xxxxxxxxx>wrote:
> 
> > I am nearing the completion of the second incarnation of my 4” Tesla Coil.
> > After a good deal of time spent polishing and cleaning the copper
> > primary I got the idea of installing an acrylic disk over it in order
> > to help protect it from dust, fingerprints, falling objects, idiots,
> > etc…
> >
> 
> That's a good idea. I incorporate this on all my flat primaries now. It
> helps smooth the e-field around the primary to a limited degree, as well as
> providing protection to the finish of the copper.
> 
> 
> > In searching the archives, I read about this being done before but
> > found nothing regarding its effect on the device.
> > I also found an acrylic tube that slides perfectly over the secondary
> > coil leaving an eighth of an inch clearance between the windings and
> > the ID of the tube.
> >
> 
> If there is ANY air between the tube and the secondary windings the tube's
> only function will be aesthetic. If you would like it to provide electrical
> protection to the secondary you will need to fill the space between the tube
> and the windings with oil or epoxy. If you don't already have the tube I'd
> suggest looking into using epoxy, it would probably be cheaper, and when
> applied properly provides a glass-like finish that is very resistant to
> racing sparks and flash over.
> 
> 
> > Aesthetically it is all very pleasing, but will that much plastic have
> > a measurable impact on the performance of the coil?
> >
> 
> If you take the steps mentioned above you would be able to push the coil
> harder without having to worry about flash overs or racing sparks.
> 
> 
> > It looks as though it may help prevent racing arcs due to the lack of
> > any direct path of air between the primary and secondary but I cannot
> > figure out in what way (if any) it might adversely affect the
> > relationship between L1 and L2.
> >
> 
> There should be no effect. You can adjust for any coupling changes you
> might have due to the inner diameter of the primary accommodating the
> secondary form.
> 
> 
> > The acrylic over the primary would be .25” and the wall thickness of
> > the tube over the secondary .125” for a total of .375" (3/8").
> > Has anyone experimented with this before or is it common knowledge
> > that this is just too much dielectric?
> >
> 
> Too much? Hardly.
> 
> 
> >
> > Thanks!
> >
> > Brandon from Jersey
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