Terry's great theory of arcs #85692875

Terry Fritz, Sun Nov 12 2006, 12:54AM

Hi,

From an off-list thing...

Terry's great theory of arcs #85692875 of this moment. Subject to change the "next moment" :o)) It's all "pie in the sky", but it should not violate known observations other than the constants are not yet determined...

So here goes...

I think arc length is governed by "voltage/length" and "current/length" constants along with a "fixed resistance - independent of streamer length". For the sake of argument I will define them to sort of close values as:

Streamer Arc Voltage = 250kV/m
Streamer Arc Current = 2 A/m
Streamer resistance = 125kOhm

That's it!! Done!!! :o))))))

But let's look at it...

Streamer resistance is constant regardless of streamer length. From modeling and testing, going into 5 years now on many odd systems, that seems "true"....

To get twice the streamer length, you need four times the power. At 1 meter we need 250kV x 2 A = 500kW peak. At 2 meters we need 500kV at 4A = 2MW peak. "Condition satisfied"...

Suppose our coil produces only 250kV, but 50 amps and 50kW. Streamer length is still limited to "1 meter" (!) No matter how hot or how many little streamers are flying off it, we only get 1 meter... This is similar to a coil with two foot arcs running from 60 BPS to 6000 BPS with no change in streamer length... You have not got the voltage, so you only go 1 meter - no matter how many kBPS you throw at it... My DRSSTC does happily go from 60 to 6000 PBS with not much change in streamer length. The streamer sure does get "hot", but not longer... "This observation is satisfied"...

Lets go for giant voltage with no top terminal!! At the secondary voltage peak, the top current is nearing "zero"(!!).... We still have the coil's self capacitance and space capacitance of the coil's bare top to drive current. But "not much" current. As we draw power, that much smaller capacitance's voltage will drop like a rock and suddenly we don't have the needed voltage anymore... It might get off to a nice "short" start, but the streamer will starve for current and the voltage will drop out. We are saved a little as the cycle can supply "direct" current "through" the secondary's inductance, before and after the top current null... But we are starving for current and streamer length will starve too... I think this is what happens to Electrum, not enough big top load capacitance to store the current supply needed for longer streamers without loosing terminal voltage. This seems to be shown in coil's that do better with bigger top terminals that are not "too big" in that they kill top voltage. - "Seems true".

There are fun "complications"...

Streamer (leader) capacitance is dynamic and seems to be about 6.56pF/m. Leader branching gets "messy", but tends to coalesce as "one". Streamer dynamic capacitance converts current to voltage loss as the streamer grows. Not a big problem, we used to use fixed values for it (~1pF/foot). But dynamic computer simulations tell us "it's not 'fixed' dummy"... But if we guess good at the coefficient, the programs are happy and they love crunching all the numbers in 1nS increments anyway.

"Load Energy Rise Time" - A new term some may not know, but it is how fast you convert primary energy to streamer energy (officially, 10% to 90% timing of top terminal energy rise). Generally observed as "the faster the better". Less time for primary gap losses to steal energy and fewer "ring ups" that might waist power due to lower voltage and current pulses observed in very recent high speed photos. If you make a bright leader that only makes it 90% there, something has got to be "waisted"... High coupling minimizes lower power leaders, and their loss. The DRSSTC folks push coupling as high as possible for better and better streamer lengths... The SISG also like high coupling... I don't think LERT is a goal, but rather a "symptom" of other things. If you do "everything else right", LERT will be perfect.

"Ground arcs" - Used to be messy, but the programs figured that out as a massive very high speed (10nS!!!) top terminal drain to ground. It sustains until the top terminal is drained of energy and the secondary is not longer able to maintain the "comparatively feeble" secondary current to sustain the arc. When the arc dies, there may be energy left in the primary to again partially re-energize the secondary system. The ground strike models seem to predict ground stick observations perfectly!!! (Thanks to Dan M. ) The speed and power of ground arcs bring up many scary new "questions" though Stand back "another" 10 feet...

So until theory #85692876, that is my take...

I really don't know the "constants"... Theory #85692874's constants are too buried in ambiguities to "simply" convert... But maybe with a more clearer view, that will be simpler. Supper time now here, so c'ya )

Cheers,

Terry