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Re: Fw: Arc Impedance Study - Computer Models

At 01:12 AM 10/11/98 -0400, you wrote:
>Hi Terry,
>    Nice analysis.  There was one last problem.  What is the best
>surge impedance for the primary?  This is related to the many turn VS
>few turn primary which is related to the question: Is it more
>efficient to transfer the energy to the secondary system with a single
>soliton like pulse or to let it transfer slowly by sloshing back and
>forth?  Would a pulse forming network delivering a precise rectangular
>pulse with a period just shy of one quarter of the secondary resonant
>period be more efficient?
>
>Barry
>
snip

Hi Barry,
	So... is a many-turn high-inductance primary better or worse than a
few-turn low-inductance primary.  This is very difficult to measure in real
coils since changing the primary inductance does the following things:

1.	The coupling will change.
2.	The primary capacitance will increase.  This will raise the primary
energy unless the voltage were to be turned down to compensate.
3.	The primary circuit resistance will change.
4.	The spark gap may act differently depending on how much current goes
through it.
5.	Just visually looking at the coil's streamers after major circuit
changes over time is not an exact science :-)

Models, however, can easily test such a change while locking all the other
variables.  The output of computer models is, of course, perfectly
repeatable and objective.

This test assumes only the primary capacitance and inductance changes.
Coupling, primary circuit resistance, and spark gap effects are locked.  I
will add a correction at the end for the difference in primary enegery
larger caps have.

Primary	Corrected				Corrected
Inductance	Peak Current	Burst Time	Relative Power
25%		492			61		3.24
50%		622			61		5.19
100%		719			61		7.17
200%		782			61		8.21
400%		814			61		8.91

So it appears that larger, high inductance primaries are better.  The
graphs show that low inductance primaries tend to have a single burst while
high inductance primaries have multiple bursts.  However, more energy is
being delivered to the arc with the high inductance primaries.  I suspect
the losses are killing the performance with the larger primary currents.

	Terry