Re: Spark-gap sparks vs. solid-state sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bert.hickman-at-aquila-dot-net>

John, Ken, and all,

John, I believe you are correct. Have you watched (in a completely darkened
room with dark-adapted eyes) a coil operating just below the point of
streamer breakout? For a disruptive coil topped with a toroid of large
minor diameter, the outermost surface of the toroid (the region of highest
E-field) is bathed in a diffuse bluish glow. Upon closer examination, it
can be seen that this glow actually consists of countless bush-like
discharges. Technically called streamer corona and coronal flashes, these
are "cold" discharges that are the predecessors to true leader formation
(or "breakout"). As the coil operates, these individual flashes constantly
flash and wink out of existence, being brighter at the toroid surface,
dimming as they extend outward to the limits of visibility. On my system,
the visible portion of these discharges extend outward by as much as 12-18"
(versus 65" leaders after breakout occurs). At this stage, the overall
average current flow is low if compared to that of a fully formed leader,
but it is NOT zero. In fact, per Bazelyan ("Spark Discharge") the peak
currents of these coronal flashes may actually be in the ampere range but
individual discharges may last only tens or hundreds of nanoseconds. 

Each of these discharges effectively transfers an increment of charge from
the toroid to the space charge in the surrounding region. This would appear
to the topload as an additional resistive and capacitive load as charge is
injected and removed from the surrounding region during polarity reversals
of the topload. Paul's latest TSSP model (Section 2) indicates that even
small resistive loading tends to reduce resonator frequency. Perhaps the
combination of the additional capacitive loading and energy loss through
these cold discharges account for the observed frequency shifts prior to
the more obvious added capacitance of fully formed leaders...

-- Bert --  
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com


Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<FutureT-at-aol-dot-com>
> 
> In a message dated 4/21/01 4:47:17 PM Eastern Daylight Time, tesla-at-pupman-dot-com
> writes:
> 
> > John (& all)-
> >
> >  No, no instrumentation--just the eyeball.  But I remain dubious of such
> >  an ion cloud for this reason (& remember, it's not an expert who writes
> >  this):  Once ion #1 forms, due to an addition of an electron from the
> >  toroid, then the next electron in line, so to speak, is going to see an
> >  easier path to "freedom" and it's going to take it.  That, in my view, is
> >  when the spark-avalanche begins.
> 
> Ken, all,
> 
> I'm certainly not an expert on the ionization issue.  I know
> that ionization can occur without spark breakout, and I would
> think this happens whenever the voltage is too low for the spark
> to break out, but high enough to form ionization.  I would think
> therefore that the ionization would occur first, then the spark
> would break out.
> >
> >  I've observed, by looking at the e-field on the scope during my 7 ms
> >  interrupted-sparking events, that the field increases very little after
> >  each ~400 us cessation of energy.  So something is preventing that field
> >  (electric potential) from increasing, during those off-times.  But, as
> >  I've said, I'd think that that would be the heat of the air rather than
> >  residual ionization, because of that relatively long time duration.
> 
> I don't see why the ionization would occur or increase during "off"
> intervals.  I'm not suggesting that the ions that remain from bang
> to bang are essential for what I'm suggesting (although they
> are a factor).  I'm saying that even a TC that is turned on
> after being turned off for a month, it will form some ionization around
> the toroid before the spark first breaks out.  I just saying that maybe
> CW coils with a slow energy buildup cause more of this ionization
> than a spark gap TC with a fast voltage buildup.  Maybe simply
> because the longer duration of build-up, gives more time for ionization to
> occur.   Yes, it would be good to hear from experts.  I get the
> impression this matter is considered "old hat" by some?
> 
> I look forward to the creation of your website.
> 
> John Freau
> 
> >
> >  --->Any light to be shed on this matter by experts??<---
> 
> >  Ken Herrick
> >