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Re: How do sparks propagate, anyway?

Subject:       Re: How do sparks propagate, anyway?
       Date:   Tue, 6 May 1997 14:28:27 +1200
       From:   "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization:   Wellington Polytechnic, NZ
         To: 
            tesla-at-pupman-dot-com


Hi Greg,
         For what it's worth here are some ideas that could influence 
the results (assuming no increase in primary energy or break rate):

> Given the large number of newbies on this list, I would like to re-visit
> an
> old issue from a 'theory of arc dynamics' standpoint -- Why do many
> coilers 
> report that a larger toroid increases the striking distance of their
> coils, 
> given that increasing Coutput always decreases the output voltage?  
> (I am assuming that the striking range is increased by more than just
> the 
> increase in toroid radius.)

      The first is that most people compensate for increasing top-C 
by tapping more primary turns in which raises the Q of the primary.
That is certainly true but how much that influences output depends a 
lot on the degree of reduction in primary losses.

      The second is that the secondary load is not constant but 
varies between heavy in the mid-latter part of a secondary ringdown 
and none in between primary cap charges. Given that ionization in the 
streamer weakens as the cap is recharging, it won't strongly re-
ignite while the secondary is ringing up on a subsequent cycle (scope 
suggests it pretty well rings most of the way up). Also, Vout is as 
you say reduced. So the question is: does it ring up more if there is 
more breakout prevention in the form of lower voltage/greater holdoff 
voltage? I guess that depends a lot on whether average throughput is
already high or not.

      A third possibility is that coupling is tightened if no change 
apart from number of turns occurs when the primary is retuned. That
would influence transfer time and also degree of transfer (could be 
more or less favourable depending on what it previously was). It may 
reduce the number of trades by one in some cases.

Gotta get a scope onto it when the caps arrive.

Malcolm