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Re: Answers to a Puzzle


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Wednesday, September 03, 1997 9:17 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Answers to a Puzzle

Hi Greg,
 
> From:   Greg Leyh[SMTP:lod-at-pacbell-dot-net]
> Sent:   Wednesday, September 03, 1997 1:25 PM
> To:     Tesla List
> Subject:    Re: Answers to a Puzzle
> 
> Malcolm Watts wrote:
> 
> 
> [snip]
> > (2) It is _obvious_ that the Q of the larger resonator is a _lot_
> > higher. Whereas the gap went out on just the second ringup with the
> > smaller coil, it went out on the fourth for the larger one. This was
> > with a very moderate air streamer for the large coil and none for the
> > smaller one (single shot).
> [snip]
> > - The single shot attached spark was a vastly higher quality with the
> > large coil (flashovers excepted).
> > - It was also an inch or so longer.
> 
> Given that the single-shot results were vastly different for the two
> coils, it would seem that efficiency factors such as Q and k are probably
> the culprits.   
> If the single-shot spark lengths were the same, then I would have suspected 
> changes in component values such at Ctot and Zsec, which directly affect 
> the arc dynamics during long arc formation.
> 
> 
> > - It is clear now that cramming heaps of inductance into a small coil
> > is not going to produce a good one despite the low Cdistr because the
> > small wire losses matter a great deal. Better to use a much larger
> > coil with a more modest terminal if primary energy is limited, OR, go
> > to a higher frequency and use bigger wire in the small coil. My rule
> > of 3 skin depths minimum for a spacewind stands.
> 
> What do you think is the lowest allowable _unloaded_ Qsec?

Good question. I'll be shooting for a minimum of 200 in all future 
coils. For a long while I was convinced by others that going beyond 
100 or so was a waste of time but recent experiments have given the 
lie to that one. Got to throw the onus back on the primary I think.
    One great thing about the scope pictures - you can see clearly in 
which part of the system the losses are occurring. The higher the Q 
of the secondary (primary notwithstanding), the more trades you get 
with light or no secondary loading since by transfering energy to a
hi Q secondary, the losses in the primary are effectively removed 
with a 50/50 duty cycle.
    It seems that the extra long reach occurs with prolonged 
oscillation in the system allowing leaders time to form as the 
terminal is never stuck at one polarity for any length of time.
However, I stand by earlier comments about energy being gone 
in between bangs regardless. I've never seen otherwise on the scope.

Malcolm