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Re: Terry's Little SISG Research Coil

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi DC,

It's not that simple :o)

Consider the bang energy. My little coil only fires off 0.4427 joules per bang. At 120 BPS that is a coil power of 53.1 watts. I am not going to get 56 inch sparks out of 53 watts ;-)) It would be interesting to make a 100kV coil that has say 50 joules behind it. I bet it would do very well ;-) But my little coil hits a very "odd" area in streamer length. It is the area were ScanTesla's active streamer models tend to break apart.

If we use the Freau formula L = 1.7 x SQRT(power) = 12.4 inches. My coil is less than that by almost half even with a very efficient spark gap! The answer there lies in this chart:


You simply can't break out a 1 inch streamer on a 4 inch diameter toroid surface. There is a jump or leap you have to go past. and that leap "steals" energy from the streamer length.

http://drsstc.com/~sisg/files/scantesla/StreamerCapacitance.pdf (big file)

A streamer not only needs enough voltage to breakout (152.4kV for a 4 inch section toroid) but there has to be enough "energy" to get past the proximity effects of the toroid.

If you remember my "new" streamer capacitance model:

Cload(pF) = (X(inches) - D(inches)) / 6(Inches/pF)

If the streamer is less than the toroid diameter the capacitance is negative (really zero) since you don't have a streamer yet. You need a four inch streamer just to "start". If the streamer is less than 4 inches, you will still not breakout even if you do have the voltage. You actually need the power of a six inch streamer to break out from a 4 inch toroid.

If 6 = 1.7 x SQRT(power) power = 12.5 watts or 0.106 joules/bang "minimum". But I have 4 times that! But do I have the energy? Let's see:

E = 1/2 x Cs x Vs^2  == 1/2 x 17.41pF x 140kV^2  =  0.1706J

So after breakout I have 0.1706 - 0.106 = 0.0646J "remaining" for the streamer. How far will that go?

120 x 0.0646 = 7.752 watts

With a variation of the Freau formula:

2.5 x SQRT(7.752) = 6.96 inches which is what I see in actual tests. The 2.5 number keeps pooping up all the time as a Freau coefficient for streamers of the top load power level.

That all sounds odd complex and "pie in the sky", which it is. But those are the types of issues that smaller streamers have near the toroid.

Of course, one will not that the streamer length is effected by BPS too... It is also affected by coalescence of the streamer. Single streamer or many branches... We are just beginning to understand all this.

This is not all supposed to make sense... It is an unknown area the new little SISG coil is meant to explore... this coil is meant to make big "numbers" not big sparks ;-)) The next coil will be more about sparks ;-))

Past the toroid area and at power levels far beyond what the above would care about, Just use John's formula and be happy ;-))



At 09:52 AM 7/19/2006, you wrote:

I was hopeful, but, unfortunately, this does not scale up very good.

Our model M-50 coil which puts out a 56 inch long spark, using your value of 139,000 volts / 7 inches at 120 pps, would be developing 56 inch x (139,000 v / 7 inch) which equals 56 inch x 19.857 kV / inch at 120 pps = 1.1 megaVolts!

I would estimate based on the 70% x Vpri x SQR (Ls/Lp) the real output is around 220 kV and not 1,100 kV.

A large differential.

Dr. Resonance

At 120 BPS it is 7 inches.
240 BPS is 10 inches.
360 BPS is 11 inches.