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Re: Racing Spark Prediction

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Dimitry,

Tesla list wrote:

Original poster: dest <dest@xxxxxxxxxxxxx>

Hallo Bart.

about the new subj line - no one on this list can explain what the racing
sparks are and from where they are comin from, so how you can predict the
thing such that you don`t fully understand?

You are exactly right. It isn't understood, but there are plenty of hypothesis.

else plz supply a link to Richie Burnett or whatever else page, where
i can read something sensible about it ; )
btw - have you experienced in person something like this racing beauty:

As I use to say when I lived in Minnesota, "OH MYYY!!", absolutely! I've witnessed all kinds of racing sparks. Sparks from top to bottom many times. On my large 13" diameter coil, I witnessed racing sparks running down from the top then abruptly arcing at 2/3 down the coil right out to the strike ring. BTW, I no longer use a strike ring. I'm one of those few that don't. It's just an "attraction for sparks" in my mind. No one has been capable of talking me in to it yet.

? there is no any conical or even solenoidal primary, but top load is
a way too small : )

Yes, it's quite small for this coil. The coil is obviously pushing a lot of power through to run the sparks lengths. But, as noted, there are problems.

btw 2 - 12 Jul 2005 Steve Coroner (^_^) said, that "FANTC can't do the
plot of the voltage distribution up the resonator when it's excited on
only one of its resonant mode - the algorithm that draws the voltage
profiles has built in the assumption of a spark gap driver that
excites all the modes at once. So the plot is a mix of (mostly) the
two lowest modes, which I believe have totally different profiles."

I haven't been made aware until now. I think Paul would have to answer this question to fully explain the VI profile distribution and what it is made up of. Maybe if Paul is listening he can help here. If not, please, ask Paul this question directly. It's a good one, and I'd bet he has a good answer. As noted in Fantc, the base current is based on 1 amp. The distribution is based on the profile and the profile is determined by geometry. Of course, to ensure an accurate current, the base current must be measured and scaled in accordance with the distribution. However, the distribution itself as far as graphical, should be the same.

does this mean that i`m fooled every time when i see a nice, almost
linear 45 deg voltage rise from bottom to top of my secondary,
independently from what form of primary or value of coupling i use?

Unsure, again, have to reference Paul on that particular.

coz where is then horrible nonlinear voltage distribution with max at
bottom of secondary, that Steve believe is the genuine reason for
racing beauty formation? : )

That is interesting! I would like to here Steve's "reasoning" for racing sparks. I've heard many theories over the years and I'm not sure about any of them. We have to prove or disprove these theory's with measurement to be sure. Without that, we are just arm-chair cowboys shooting in the dark. My theory is rather simple. First, there is a potential along the secondary which is high enough ionize and promote a breakout. Once the breakout occurs, it finds it's way to ground in the fastest path possible (right along the side of the coil directly below it's breakout point). What actually causes the hv points along the coil to breakout are really what is in question. We can conjure up all kinds of theory's here. Under some conditions, the highest gradient point is not quite at the top of the coil, but somewhere along the coil?

or this  voltage profile is valid only for uncoupled secondary? can you
wrote a little proggy that would do such plots for any situ? it is not
for "coilers" of course, but maybe you already have it ; )

Sorry, no, it isn't written for any possible profile. There are assumed profiles from linear to non-linear based on geometry. Possibly however, it could be modified to allow whatever profile desired to be an input function.

btw 3 - i downloaded fantc "Updated 12/12/05" - why the heck i can`t
put (or leave) zero value in "DEFINE SECONDARY - Bottom Height" field?
when i do this i get runtime error on line 194 "s_height1 - definition
is missing", but when i enter say 0.001 in there and then change this
value back to zero at once - the program works fine?

I may know what this is. Please, send me exactly your input values (0, numbers, and null values). This may be due to the calculation fields (there is an issue I ran into a few years ago with such fields. Possibly the same thing has been introduced). Send me your values so I can re-create the same situation, then I can fix it.

can you (or John) supply any physical explanation of why high k is
different from low k - in principle, or what the reason for such
innaccuracy anyway?

I cannot.
Coupling should be ok with high or low k. I don't understand the mechanism John has mentioned and I've only built coils up to 3.5 k. Those were fine as I measured via AC current method as well as verified with calculation. However, I haven't built up to a k of 0.6, so I can't verify those numbers.

Take care,