Re: Power vs. Spark Length

From: 	FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
Sent: 	Saturday, July 26, 1997 3:27 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Power vs. Spark Length

> Being basically a practical type guy who enjoys the buildin' and
> measurin' more than the theorizin', it seems to me that we have some
> major problems measuring the performance of a TC without knowing the
> peak voltage and current produced in a given spark. My 15KV 60Ma TC for
> instance gives reasonable length sparks (no threat to the record
> holders!) but my sparks are always fairly spindly and violet coloured.
> On the other hand, I notice a lot of you guys with the bigger current
> inputs seem to get sparks that are not that much longer, but much
> brighter, white or blue sparks.
> It seems to me that you need a certain voltage to break out of your
> toroid but from then on current is more important. Possibly this would
> explain the vastly different performance of different TC's running at
> around the same input power levels. Some of them likely produce very
> high voltages but lower currents while others produce lower voltages but
> much greater currents. An added variable is the freq. of operation (at
> least this is easily measurable). Maybe the best way to measure the
> performance of a TC is to use absolute maximum spark length v brightness
> (as measured by a photometer) v freq.


I don't see much difference using frequencies anywhere from 50 kHz to
600 kHz.  But different break-rates seem to have a large effect on the
voltage vs. current aspect of the sparks, and I suspect that this accounts
for a lot of the differences that are seen.  Toroid size can also affect 
current vs. voltage I think.  I agree that the brightness should be 
considered when comparing coils, otherwise the dim sparked coils will
have an (unfair?) advantage.  another thing I've noticed is that as more
power is poured into a coil, many more streamers are produced at one
time, (maybe, actually depends of toroid size) ...so many variables...it 
can make one's head swim in a sea of ionized plasma   :^)
> Has anyone actually attempted to directly measure the peak voltage in a
> TC?
I've heard of such measurements, but do not know if they accurate.  It 
would be good if we could measure both the voltage and current in the
sparks as you said.
John Freau

> Trying to get the radius of the arc's longer in Aus...
 >Peter E.