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

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Bert,

On 23 Apr 01, at 8:00, Tesla list wrote:

> 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 --  

I have seen exactly that on one occasion. I was not expecting it. I 
observed a ball of wispy streamers about 3' or so in diameter 
emanating from a 9" sphere. At first I couldn't believe what I was 
seeing. This must be the source of the pre-breakout C and shunt 
resistance. This resistance is high though. Scoping the e-field shows 
Q dropping by very little.

Regards,
malcolm
<snip>