Re: conical secondaries (fwd)

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---------- Forwarded message ----------
Date: Sat, 16 Jun 2007 12:16:55 -0700
From: Ed Phillips <evp@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: conical secondaries (fwd)

Hi Gary,

Probably the best way to test my observations would be to build three coils,
each with the same wire length, wire gage, and same number of turns for each
of a flat spiral, solenoid, and conical coil.  The best cone design would be
a height equal to the base diameter, or nearly so.  Then it would be a
simple matter of choosing a constant top load and variable power supply.  I
predict the conical coil will handle more power than either the flat spiral
or solenoid coils.  I doubt it would increase the spark length by much, but
the spark will be brighter and more robust in a conical coil than in a
solenoid coil.  Since the specific application here is a very small coil,
the conical coil could make the difference between being able to see the
streamer or not seeing the streamer for a given coil size.

BTW, my observations are based upon the two different manifestations of
sparks I observed and spoke of earlier.  A flat spiral coil produces a
thick, white arc indicating maximized current.  A solenoid coil produces a
thin purple spark, indicating maximized potential.  

The solenoid coil is too narrow at the base to accommodate a flat spiral
maximized current, and a flat spiral has no height at the terminal to
accommodate a solenoid maximized potential.  The conical coil accommodates
the high current and high potential both, thus allowing more power to be
stored in the coil per coil size.

Dave"

	For the same amount of coupline I'd think that coils with the same surge impedance [sqrt(Ls/Cs)] would have equivalent performance.  While the conical and helical coils could be wound for similar impedance I think it would be very hard to get the inductance in a practical flat spiral but not a bit sure.

Ed