# SPARK LENGTH vs. VOLTAGE

From: 	Wysock, William C.[SMTP:Wysock-at-courier8.aero-dot-org]
Sent: 	Tuesday, January 20, 1998 9:04 AM
To: 	Tesla List
Cc: 	ttr
Subject: 	SPARK LENGTH vs. VOLTAGE

Dear List members;

Iike many of you, I have been following the thread on this list
discussing various thoughts about spark length vs. voltage.
In particular, I read with interest, Greg Leyh's account of data
taken on his 45 kw coil.  I don't think any of us have the
definitive "last word" on this subject, as of yet.  I had (previously)
posted to the List some comments, based on my own
experience.  Specifically, I made a reference to a published
paper in the IEEE.  I encourage others to read this publication.
It is: Kotter, R.F., Smith, A.N., "A Study of Air-Gap Breakdown
At 28.5 Khz."  IEEE Trans. Vol. PAS-102, No. 6 (1983) 1913.

In writing about the results I obtained in November, 1995, while
testing my Model 13M Magnifier coil, I used this reference to
correct my own work.  I had measured (across a 40 foot gap,)
an average of 39 arcs/second.  Based on the input power delivery
rate of 125 Kva, I calculated that there was approximately 0.833 KW
of energy in each spark, for an output energy delivery rate of
32.4 KW/second.  The maximum measured (straight line) strike
distance that was recorded from this coil was 55 feet.  From the
above reference, taking 8.4 KV/inch (my frequency was higher
then the reference: 85 Khz vs. 28.5 Khz,) a spark length of 55 feet=
660 inches=5.54 MV.  This of course, does not come close to what
I had originally believed to be > 16 MV!

Building a non-inductive resistance voltage divider (and calibrating
it,) for measurement of R.F. voltages, say up to 100 Khz, will be an
arduous (and expensive!) task.  Not to mention the physical size
required, for measuring such high potentials!  Even if someone does
come up with a workable divider, there is the issue of having it
calibrated to some known and acknowledged standard i.e., NIST,
(also an expensive proposition!)

At this point, I would suggest to List members, that statements of
"x" KV or "x" MV, are moot.  Straight line measured spark length as
well as disclosure of the gap geometry, may be the only reliable
and consistent benchmarks we have as tools, to work with.

Bill Wysock
-------------------------------------------
Tesla Technology Research