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Re: Streamer Capacitance (Was how to rise the secondary) (fwd)



---------- Forwarded message ----------
Date: Sat, 18 Jul 1998 11:01:33 -0500
From: Bert Hickman <bert.hickman-at-aquila-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Streamer Capacitance (Was how to rise the secondary)

Dale,

Your thinking is not flawed! The situation is simply more complex -
how's that for an oxymoron! There are at least two or three plausible
mechanisms that appear to be at work around, all of which would tend to
increase the "effective" capacity of the system. And, your speculation
of alteration of the media may not be very far off the mark... 

The first two mechanisms have to do with corona and space-charge
effects. Suppose you start with 2-coil system having a good-sized Radius
of Curvature (ROC) toroid. Now carefully adjust the output of the system
so that it's just before streamer breakout and observe operation in a
very dark room (eyes dark-adapted). You'll notice that the region around
the toroid, as well as much of the space between the toroid and primary
coil, may be illuminated with a diffuse bright bluish glow that looks
similar in color to corona. While this glow brightens near the
terminations, the vast bulk is not really "attached" to either the
toroid or the primary/strikerail. Tesla often demonstrated this effect,
and speculated that it could be used as a source of room illumination.

There's evidence that "waves" of charged particles are being generated
and subsequently acellerated to/from the toroid under the influence of
the rapidly changing HV E-field, and in the process creating additional
ionization away from the terminations. This is sometimes referred to by
coilers on this list as an "ion cloud", but its dynamic structure is
probably much more complex than a localized "cloud" of ions would
suggest. Also, in the immediate vicinity of the toroid, small (inches
long) scintillating corona discharges may also be observed. These
"attached" corona discharges will tend to increase the "effective
diameter" (and the apparent capacitance) of the toroid. BTW, this latter
effect was noted in the early days of spark radio - when the edges of
air-insulated capacitor electrodes began to break down, causing a
significant increase in capacitance. The combination of the two effects
may account for "pre-breakout" (streamer-wise) capacitance increases.

Finally, there's also the effect of streamer capacitance. Greg Leyh's
in-situ measurement of actual streamer currents clearly indicated the
discontinuous current flows from initial breakdown and streamer
reignition after voltage zero crossings. [Even more interesting though,
was the fact that large current spikes due to streamer propagation only
occurred during positive polarity half-cycles, but significant current
flow was occuring in both directions to the streamer and its
tributaries]. Your reasoning is sound - streamer loading capacitance
should have virtually NO impact during initial ring-up of the secondary
at the beginning of each bang and prior to streamer formation. It should
have an impact after initial ringup, and most certainly would have an
impact during ringdown, particulalry if first-notch quenching does not
occur. 

The bottom line: the combination of these effects results in a
measurable increase in effective capacitance. It can be measured
empirically by comparing "instrument-tune" versus "best-performance
tune" and back-calculating the shift in total secondary:toroid
capacitance. I've measured about a 3% shift in frequency on my 10"
system, or about a 6% increase in apparent capacitance. Your mileage may
vary.

Safe coilin' to you, Dale!

-- Bert --

Tesla List wrote:
> 
> ---------- Forwarded message ----------
> Date: 17 Jul 1998 12:20:46 -0700
> From: Dale Hall <Dale.Hall-at-trw-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: RE>Re: How to rise the seco
> 
> RE>Re: How to rise the secondary? (fwd)
> 
> Robert & All,   (Urination aside)
> 
> Re: delta fo: Might there a difference between a streamer attaching AFTER
> the charge of Ctop and a fulltime wire which is part of Ctop DURING charge ?
> invalidating the the premise of:  "a conductor connected to the topload of a
> TC to simulate an attached streamer.....".   the affect is observed but is the
> assumption of its cause valid, proven ?
> 
> I tried to express this in an earlier submission to the list but haven't evoked
> response.
> 
> Perhaps my thinking is flawed regarding the TIME relevance of streamer
> attachment ? I offered an alternative of dielectric alteration (ozone & nitrous
> oxide) in the presence of 100's of long streamers may account for delta
> Fo, as it hangs around awhile, dissipating slowly relative to Ctop charge freq
> in 100's kHz or the Ctop arcs with 2Mhz to 50Mhz freqs (streamer discharges switch/attach/deattach on/off very fast).
> 
> Dale  (all alone in a vacuum, but cranking the idea machine)
> ------------------------------
<SNIP>