Mike, here it is.
The resistivity of amorphous carbon is 35 u ohm meters
(That's a 1 meter cube)
A 1" cube has a resistivity of 1.4 m ohms, a one inch sphere about 3 m ohms.
100 kA for 20 us dumps 600 J into it.
The density of carbon is 2.3 g/cm cubed
The 1 inch sphere has a mass of 20 grams
The specific heat capacity of carbon is 700 J/kg k
The observe heats 43 deg C
Dave WX7G
On Jul 27, 2012 2:18 PM, "Mike Waters" <mikewate@gmail.com> wrote:
> Man, I don't know, Dave. How long have they been selling those carbon balls
> for that purpose?
>
> I don't have the figures in front of me, but carbon has a significant
> amount of resistance. (Maybe that's the secret: the current gets limited as
> a result. :-)
>
> It would be interesting to calculate the resistance of a carbon sphere
> sometime (how big are those?). Then we could roughly estimate the voltage
> drop across it and so come up with a ballpark figure of the instantaneous
> power dissipated in those balls.
>
> At that point, someone with way too much time on their hands could estimate
> the temperature rise based on the specific heat of carbon. :-)
>
> 73, Mike
> www.w0btu.com
>
> On Fri, Jul 27, 2012 at 2:42 PM, DAVID CUTHBERT <telegrapher9@gmail.com
> >wrote:
>
> > www.rossengineeringcorp.com/toroids_spheres_corona_nuts.htm
> > On Jul 27, 2012 9:43 AM, "DAVID CUTHBERT" <telegrapher9@gmail.com>
> wrote:
> >
> >> <http://www.rossengineeringcorp.com/toroids_spheres_coronary_nuts.htm>
> >>
> >> Ross recommends carbon for lightning.
> >> On Jul 27, 2012 9:33 AM, "Mike Waters" <mikewate@gmail.com> wrote:
> >>
> >>> I don't think carbon balls are suitable for lightning protection. Think
> >>> of
> >>> the voltage drop that would appear across each ball during a direct
> hit.
> >>> I
> >>> think they would vaporize.
> >>>
> >>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
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