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Re: TC Electrostatics (fwd)



Tesla List wrote:
> 
> Subscriber: lod-at-pacbell-dot-net Sat Jan  4 21:53:04 1997
> Date: Sat, 04 Jan 1997 17:54:07 -0800
> From: lod-at-pacbell-dot-net
> To: tesla-at-pupman-dot-com
> Subject: Re: TC Electrostatics (fwd)
> 
> Bert Hickman wrote:
> [snip]
> > > > Increasing Cp, Vg, and X, or decreasing Cs will increase Vs. However, Vs
> > > > increases linearly with increasing Vg, but only as the square-root of
> > > > the ratio of Cp/Cs. Large systems tend to significantly increase both Vg
> > > > and Cp, while only moderately increasing Cs (to protect the secondary
> > > > and prevent breakout at higher voltages). Not obvious from the simple
> > > > equations above is that while increasing Cs may reduce output voltage,
> > > > it may increase overall coil performance and sparklength for a variety
> > > > of other reasons! Trying to maximize output voltage is not the whole
> > > > story.
> [snip]
> > > > -- Bert --
> 
> Hi Bert,
> Great analysis -- Starting with the conservation of energy is a good way
> to arrive at a practical conclusion.
> I am curious to know your opinions on what other parameters besides Vout
> are important to overall coil performance.
> 
> -GL

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. 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. 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 --