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Re: Capacitor C/Peek

Tesla List wrote:
> 
> >From hullr-at-whitlock-dot-comThu Oct 31 22:33:59 1996
> Date: Thu, 31 Oct 1996 12:08:55 -0800
> From: Richard Hull <hullr-at-whitlock-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Capacitor C/Peek
> 
> Tesla List wrote:
> >
> > lotsa' snips
> > |
> > |>Robert,
> > |>
> > |>Your post got me thinkin' about coil efficiencies again...
> 
> > big snip
> > |>
> > |>We can compute the ratio of maximum secondary output energy versus
> > |>initial input energy per bang:
> > |>
> > |>   Ep = Initial energy = 0.5CpVgap^2
> > |>   Es = Max Sec Energy = 0.5CtVsec^2
> > |>
> > |>The Energy Transfer Ratio = Es/Ep per bang
> > |>
> > |>Plugging in some specific parameters for my coil:
> > |>My "single shot" low duty cycle output spark length is about 20", which
> > |>I estimate to be about 400,000 volts, The toroid capacitance is about 26
> > |>pF. My
> > |>primary gaps are set for about 19 KV, with a primary tank capacitance of
> > |>0.0205 uF. The previously measured primary Q was about 11 with the gap
> > |>firing (no secondary), so my primary performance seems typical enough.
> > |>Plugging in these values I get:
> > |>
> > |>   Ep = 3.7 Joules
> > |>   Es = 2.1 Joules
> > |>
> > |>   Es/Ep =  56% (!)  (per-bang)
> > |>
> > |>This is a much better than 15%...ven higher power, coilin' to ya!
> > |>
> > |>-- Bert --
> > |
> > |
> > Bert,
> 
> Musta' not seen this one first pass.  I think your efficiency is so high
> due to non-measured assumptions of Vsec.  If you were just 50Kv too high
> in your GUESS you would have 1.6 joules out for an efficiency of 43%.
> Estimates of output voltage, especially regarding efficiency, is like
> just blurting out a estimated efficiency right off the top of your head.
> 
> I realize your are at least out there tryin', but as Rutherford once
> said, "you might as well be talking moonshine".  See my post on possible
> efficiency measurements and what we need to call output.
> 
> Richard Hull, TCBOR

Richard,

I fully agree about the lack of precision of the measurements, but I bet
I'm at least in the ballpark. I honestly don't have any good way (yet)
to directly measure output voltage under high power pulsed conditions.
My earlier post was more of a "thinking-out-loud" type of calculation,
and certainly did not reflect precise measurements. 

However, I tried to set a reasonable _lower_ value for output voltage
(by using 20 KV/Inch under single-shot conditions) as well as only using
the toriod's capacitance (with no coil self-C). The intent was to avoid
overstating estimated secondary energy. In all the references on
sparking potential, I've not seen any references that take me
significantly below the 20kv/inch level for single-shot discharges -
although there are many references for much higher values.

But suppose in actuality I am at only 43%, or 36%, or some other more
precisely determined value - the point is that, even using a reasonably
low estimate of output voltage and capacitance, we _still_ obtain a
primary:secondary transfer efficiency that's significantly higher (by a
factor of 2-4) than levels previously posted, even when including the
the "lossiest" portions of a system. This sounds like GOOD news in our
common quest for bigger sparks!

After now doing some PSPICE simulation runs, plus some additional
theoretical work, I remain even more convinced that primary:secondary
energy transfer efficiencies are _much_ better than many coilers have
previously thought, and that 50% is not a barrier. (Again, GOOD news for
bigger sparks!). I think, once we more accurately measure the output
voltage via a calibrated capacitive divider, the hard numbers will
confirm this as well.

I'm really lookin' forward to Robert's planned measurements this Spring,
or maybe some of Malcolm's measurements...(hint, hint...)  :^)
 
Safe coilin' to you, Richard!

-- Bert --