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Re: The worlds Largest Coil
comments gently folded throughout to add texture...
>Original Poster: "Jim Lux" <jimlux-at-jpl.nasa.gov>
>
>Some more calculations..
>
>Assume a spherical top load 10 m in radius (32.5 ft, 390 inches) = 1100pF
I love how you just toss that out....lol....a 10M stainless monocoque sphere
is a rather impresive item by itself. It will be beautifull.
>Assume a secondary 20 ft in diameter and 100 ft high with windings every 3
>inches = 166 mH
That's the full tower size, will such a large sec be required?
What would the best method of construction be? Fiberglass encased tower?
What are the options for tower construction other than wooden form (the
costs of the Sitka would be staggering for such a design).
And I don't think they make PVC that big :)
Also, with a tower of this size there comes another problem. We cannot wind
it with conventional means. The tower will have to be built, erected, then
wound by a suspended spool and a guy in a rappeling harness. Plan on that
person spending the better part of a full day in that harness laceing wire
into pre-machined slots in the tower while another person either operates a
crane holding the spool, or a dolly on the ground traveling a circular path
(though supporting the wire weight for the winder would be hard like this).
>Self C of secondary is another 500 pF
>
>Resonant frequency is about 10 kHz..
That's nice and low, well under most broadcast radio (FM is 88 to 108 MHz).
>At this frequency, the impedance of the secondary is about 10.4 Kohm.
>
>Say we want the Q of the secondary system to be at least 10.. The wire
>resistance needs to be <1 K.
>There is about 25000 ft of wire in the secondary, so we want our wire to be
><40 ohms per thousand feet.. or AWG 24. In reality, you'd probably want a
>design Q of 100, so you'd want <4 ohms/thousand feet, or AWG 14... This is
>readily available in long lengths at a reasonable price.
What's the largest spool we can get from Beldon? 5000'? How do we splice it
while winding? With 3" between turns it should be easy.
Perhaps you'd go
>to #10 or #12.
>
>Another idea is to make the resonant frequency some nice multiple of 720
>hertz, so that you can use resonant charging from a 3 phase 60Hz supply.
>720Hz is figured based on positive and negative peaks of each phase, with
>two feed transformers, one Wye and the other Delta (essentially a 12 pulse
>rectifier).
DC coil?
>
>It seems a bit tough to get the resonant frequency down that low (you'd
>have
>to have a LOT more turns on the coil) (frequency goes as sqrt(L), and L
>goes
>as N^2, with the net result that you'd have to have 10 times the turns)
>
>However, make the Q high enough, and don't pump every cycle of the
>resonance. If the Q were 100 (say), and the resonant frequency were set to
>7200 Hz, you would put a power pulse in every 10th cycle. The maximum
>energy in the system would then be 10 times the pump energy.
>
>With the 10 meter diameter top load, the maximum stored energy would be
>1000pF * (10*3MV)^2/2 = 448 kJ. so your pump energy (per pulse) would be
>45kJ per pulse. At 720 pulses/second, the power draw would be about 32MW.
>The secondary winding would be dissipating that much heat, by the way.
We will dissapate 32 MILLION WATTS through the windings? Wow.....
Is there any way to NOT waste so much energy?
>
>It would be a relatively feeble lightning stroke too, at 15 kJ/meter. (But
>still mighty impressive...)
>
15000 joules per meter.....what is average for a good coil?
Would a smaller tower (80') get us more power, thicker strokes?
I want the longest hottest discharge we can get. I want to be able to see
this from miles away.
>
>How much would this cost? A bunch, but mostly in structural components..
Chris B.
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