Re: the cure for racing sparks

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

Original poster: "boris petkovic by way of Terry Fritz <twftesla-at-qwest-dot-net>" <petkovic7-at-yahoo-dot-com>


Hi Terry,

The primary resonant frequency of his coil was
significantly above selfresonant frequency of
secondary when he got 1' arc between coils?If so than
that was "potato" action I mentioned on tssp list and
not necessary related to sudden streamer formation on
top and its (possible) effects to lower portions of
coil  Paul considers in that animation.
Can you tell was the power arc lenght 1' from its
start or firstly shorter but than quckly traveled
upwards in excess of 1'+.

regards,
Boris

P.S. To others :Please don't ask what is potato action
  


> A local coiler here was tuning up his coil for the
> first time.  His coil is
> very similar to my big coil (he was using mine as a
> model).  When the thing
> was out of tune, he could arc 1+ foot long arcs from
> about 6 inches up the
> secondary to the primary coil.  At the time, I could
> not possibly imagine
> how he could be getting such high voltages so close
> to the base of the
> secondary.  They were easily in the 150++kV range. 
> Not streamers, but hard
> snap voltage arcs!!  I wish I had a picture...  I
> was thinking that it was
> do to the turns ratios between the primary and
> secondary producing those
> high voltages.  But as everyone explains to me, the
> coupling is too low for
> that.
> 
> However, your animation shows just such an effect!! 
> The only thing wrong
> with the coil was the tuning ws off, (it was very
> sharp).  Once the coil
> was in tune, it ran perfectly.  The coil never
> showed signs of racing arcs.
> 
> BTW - I am a little behind on the top volts probe
> :o))  I had better get
> that done...  I just got a couple 'more' Pearson 411
> current monitors off
> ebay today too :-))
> 
> Cheers,
> 
> 	Terry
> 
> 
> 
> At 04:01 PM 7/13/2002 +0100, you wrote:
> >Antonio wrote:
> >> ...streamer formation? Maybe as lightning
> ...about 0.3 m/us? 
> >> ...operating frequency of 100 kHz has 10 us. A
> streamer could
> >> then move 3 m in the time of one cycle. The
> numbers look close
> >> to what could cause problems, but not quite there
> yet.
> >
> >Yes, we're in the same ballpark, but as you say,
> the numbers don't
> >quite agree unless we take it that streamer
> extension only occurs
> >during quite small portions of the RF cycle, eg the
> bits marked #
> >below, and it might even retreat a little during
> the o portions.
> >
> >      #  #                            #  #
> >   #        o                      #        o
> > o            o                  o
> >o              o                o
> >                o              o
> >                 o            o
> >                   #        o
> >                      #  # 
> >
> >Perhaps we might gain a factor of 5-10 from this,
> thus forming
> >circa 30cm per RF cycle?  I guess with racing arcs
> of case #2,
> >the problem should manifest more with higher
> frequency coils. 
> >Is there evidence of this I wonder?
> >
> >Streamers often seem to display a segmented
> structure - say 2-4
> >distinct sections, brightest at the base near the
> topload, weakest
> >at the extremities, with well defined boundaries
> between sections.
> >Perhaps if an N section streamer forms over N half
> cycles it would
> >account for this appearance.  Does anyone have a
> good photo of
> >this effect?
> >
> >It'll be real nice to see topvolts scope captures
> from breaking-out
> >coils because of lot of this stuff can then be
> checked out pretty
> >quickly, I think.
> >
> >I'll just add another case to the list, 
> >
> >#A Rapid changes to topload boundary conditions
> during streamering.
> >   Scatters energy into HF modes. (VC)
> >
> >Here's a little animation which illustrates the
> idea behind case #A
> >
> >
>
http://www.abelian.demon.co.uk/tssp/pn040502/tfsm1-h1d2.anim.gif
> >
> >The time axis should be mS not uS as shown. This
> model is of a
> >rather unnatural short discharge from the topload. 
> Not quite case
> >#8 because the discharge arc is not maintained in
> this model, but
> >similar to case #A.  We see the transient bounce
> along the coil a
> >couple of times, dispersing as it goes, until
> eventually the coil
> >is awash with random HF ringing.  Along the way, it
> can produce
> >some pretty nasty voltages.  With case #A you'll
> have to imagine
> >lots of small transients instead of the one big one
> modeled here,
> >but the effect is to fill the coil with HF noise.
> >
> >Scope trace capture of the coil base current during
> streamering 
> >would give enough data to say if case #A is
> happening or not.
> >
> >Case #8 might show discharges from near the middle
> of the coil
> >occuring only in coincidence with discharges from
> the topload.
> >
> >Case #A might show thin weak arcs racing all over
> the coil, but
> >only when the topload is issuing streamers.
> >
> >Does anyone have any examples of these cases?
> >--
> >Paul Nicholson
> >--
> >
>