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Re: TC Electrostatics (fwd)



Tesla List wrote:
> 
> Subscriber: lod-at-pacbell-dot-net Mon Jan  6 22:34:56 1997
> Date: Mon, 06 Jan 1997 20:43:02 -0800
> From: lod-at-pacbell-dot-net
> To: tesla-at-pupman-dot-com
> Subject: Re: TC Electrostatics (fwd)
> 
> Bert Hickman wrote:
> 
> > Greg,
> >
> > Thanks! I'll assume good pulse-rated caps and good, high-Q, construction
> > techniques are a given. After looking at Robert Stephen's video, and
> > reviewing the data from Chuck Curren on the Cox'es coil, I'm beginning
> > to think that rotary quenching performance may not be nearly as critical
> > as I once thought. Bang size and rep rate have got to be key parameters.
> > In the final analysis, brute force power can overcome _lots_ of other
> > system inefficiencies! :^)
> > Another big factor would have to be sizing the ROC of the top terminal
> > and E-field control so that it does not break out prematurely, and that
> > streamers don't preferentially strike downward to the primary.
> 
> I've always wondered about this:  doesn't the presence of a streamer on
> the top electrode completely compromise the break-out voltage by acting
> as a wire, or a pointy conductive stick?  After all, doesn't the next
> output pulse usually build upon the end of an existing streamer?
> 

A well formed streamer certainly represents a weakenned area. With
disruptive coils there's considerable dead-time between "bangs" which
should permit a significant degree of ion recombination and thermal
cool-down of the arc channel, particularly as you move outward to the
"thinner" portions. While there's still a "weakenned" area that the next
bang will preferentially break down, it can apparently hold off a fair
amount of voltage (but less that the originl amount required to form a
brand new channel). Even if we assume a low Z channel formed at a rather
low reignition voltage, the one-way energy transfer which occurs from
T=0 to the first primary notch would assure that a significant portion
of the transferred energy goes into heating/extending it.

> > Certainly
> > the length of the secondary is also a significant factor - it must be
> > long enough to provide adequate physical seperation between the toroid
> > and the primary as well as to itself on a 2-coil system. Larger
> > diameter, squatter coils might otherwise be better performers with their
> > higher L versus C ratio.
> 
> What do you see as the optimum value for Zo (Zo = sqrt[L/C])?  I used to
> think that something around 20,000 ohms was optimum, but now I'm starting
> to think that values closer to 35,000 ohms might be better.
> 

I really don't have a good feel for this one, since my experience has
only been with relatively high-Zo coils. Does the 35,000 ohm value come
from the empirical data you've gathered on other coils? 

> > Electromagnetic coupling between
> > primary:secondary should be as tight as insulation will withstand - and
> > probably close to a "magic" value to reduce energy-stranding in the
> > primary circuit. I'd really like to see if 0.28 could be achieved on a
> > 2-coil system! A low-impedance path between the coil base and the other
> > "plate" of the secondary's capacitance is a significant factor, more-so
> > with lower Zo coils.
> > Coil Zo itself is a poser! Obviously using too fine a wire gauge can
> > hurt performance, but a lot has to do with whether its direct driven
> > (no-one will dispute RH's results using a 30 Gauge resonator!), and the
> > degree to which the coil is behaving as a distributed transmission line
> > or a lumped LC.  Results on your big coil, and Cox's Milwaukee Museum
> > coil seem to indicate that heavy topload C is not an automatic
> > prerequisite for great performance!! BTW, do you have any conclusions
> > from the Zo/coil performance information you were gathering last year?
> >
> > Still lots of mysteries in coiling, Greg!
> >
> > Safe coiling to you!
> >
> > -- Bert --