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Re: More on sparks- Bert's 4/29
Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
Hi Ralph and all,
The empirical evidence (from numerous HV lab impulse tests and confirmed
by Greg Leyh's direct measurements) is that leaders propagate when the
magnitude of the topload voltage is increasing, preferentially during
positive half cycles. It is possible that minor growth can occur during
increasing negative potentials on a pre-existing leader, but negative
leaders tend not to propagate nearly as efficiently as positive ones.
However, during negative excursions, displacement current does now flow
"backwards" from the leader and nearby (hotter) streamer regions to the
topload, helping to keep the leader channel hot (conductive), and also
returning part of the reactive energy stored in the leader's isotropic
capacitance back to the system. In a large system, leader growth can
occur in multiple jumps during ringup within a bang as well as from bang
to bang. In either case, greatest propagation occurs when the topload
potential is becoming increasing positive.
The actual position of the toroid vs the top of the winding is really
not critical. Elevating the toroid will increase its effective
capacitance, but raising it too high will prevent it from adequately
shielding the top of the resonator winding. Because of height
restrictions of the room, the lowest portion of my toroid is actually
about 2" _below_ the top of the winding...
-- Bert --
Coins Shrunk Electromagnetically!
Tesla list wrote:
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> Hi Bert,
> That's very nice. The avalanche of information has left many nonuniform gaps
> in my understanding. Q: the description discusses positive and negative
> electrodes. What happens at the AC toroid? Or did I miss something?
> But the above is not the reason for this note. I wanted to axe you what the
> spacing should be between the bottom of the toroid and the top of the
> secondary. John F says one inch.
> I see pictures with all manner of spacing that ranges from the plane of the
> toroid below
> the top of the sec, to something 3-4 inches above. What determines the
> The toroid is a big 8 x 28.