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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 Ken,

Hope it helped a bit. The path electrons are removed makes a BIG
difference. When a leader propagates, it does so by transferring
significant charge from the topload. Long sparks come from "stiffer"
voltage sources. A leader will continue to propagate as long the E-field
at the conductive leader tip remains sufficient to continue ionizing the
air ahead of it (~26-30 kV/cm). However, the voltage drop across the
lossy leader, combined with the voltage drop at the topload due to
charge being removed from the topload isotropic capacitance, mean that
eventually the leader's tip potential is too low to maintain ionization
and further growth stops until the terminal potential can be raised
sufficiently to restart the process. 

At the short (10's - 100's of nanosecond) timeframes for leader
propagation, the topload behaves mostly as a charged HV capacitor. The
path of incoming leader electrons is directly into the topload
capacitance - the larger the topload, the less effected the topload
voltage will be as slugs of charge hit it during leader extensions. Big
toploads drive longer sparks. The resonator below then serves only as a
source for replenishing topload voltage/energy/charge (pick any) during
ringup. Faster topload charge replenishment (larger peak power) also
drives longer sparks.   

Best regards,

-- Bert --
Bert Hickman
Stoneridge Engineering
Coins Shrunk Electromagnetically!

Tesla list wrote:
> Original poster: "K. C. Herrick by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>
> Bert (& all)-
> An admirable run-down.  Thanks!  I'm sure it will benefit others as well
as me.
> One more thing occurs to me to ask about & then, perhaps, I'll shut up:
With a
> positive active electrode, electrons that hit it are "removed"--but I
wonder if
> it makes a difference as to the nature of the path by which they are to be
> removed.  In many instances, that path might be a relatively
low-impedance one,
> back to a power supply.  But in the case of a Tesla coil, it would seem to be
> via the secondary coil to ground.  Is the ease of "removal" different in the
> two cases and if so, would that make a difference in the characteristics
of the
> spark?
> Ken Herrick