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Re: Capacitor C/Peek


Clark and Ryan?  What is the citation for this paper?
Sounds interesting.
Barry
 ----------
|From: "tesla-at-poodle.pupman-dot-com"-at-PMDF-at-PAXMB1
|To: Benson Barry; "Tesla-list-subscribers-at-poodle.pupman-dot-com"-at-PMDF-at-PAXMB1
|Subject: Re: Capacitor C/Peek
|Date: Tuesday, October 29, 1996 1:43AM
|
|<<File Attachment: 00000000.TXT>>
|>> Subject: Re: Capacitor C/Peek
|
|From rwstephens-at-ptbo.igs-dot-netMon Oct 28 21:24:07 1996
|Date: Mon, 28 Oct 1996 11:36:49 -0500
|From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
|To: tesla-at-pupman-dot-com
|Subject: Re: Capacitor C/Peek
|
|>>From bert.hickman-at-aquila-dot-comFri Oct 25 21:59:07 1996
|>Date: Fri, 25 Oct 1996 13:20:22 -0700
|>From: Bert Hickman <bert.hickman-at-aquila-dot-com>
|>To: tesla-at-pupman-dot-com
|>Subject: Re: Capacitor C/Peek
|
|>Tesla List wrote:
|>>
|>> >From rwstephens-at-ptbo.igs-dot-netThu Oct 24 22:57:34 1996
|>> Date: Fri, 25 Oct 1996 00:37:12 -0500
|>> From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
|>> To: tesla-at-pupman-dot-com
|>> Subject: Re: Capacitor C/Peek
|>
|
|><SNIP>
|
|>> Now take a 12000 volt RMS xfmer and charge a 0.125 mfd cap to 16968
|>> volts.  That's 17.99 Joules.  Bang this in 5 microseconds and your
|>> sinewave peak power is 5.088 megawatts!  That's approximately the
|>> spec of R. Hull's Nemesis coil and exactly those of my MTC system. My
|>> first half sinewave is 6.25 microseconds though (80 kHz), so my 
theoretical
|>> peak power is lower at merely 4.07 megawatts, and then taking K=0.2 and 
gap
|>> losses into account I'm down to maybe 15% of that (a measely 610 
kilowatts)
|>> out the top?
|>>
|>> I realize that the above is fast and simplified 'figurin' which
|>> ignores a lotta stuff so flames are welcomed if I'm out more than 10 db. 
:
|)
|>>
|>> rwstephens
|
|>Robert,
|>
|>Your post got me thinkin' about coil efficiencies again...
|>
|>What if we look at this from a slightly little different light: How much
|>energy
|>do I start out with in the primary, and how much do I end up with in
|>the secondary after I've transferred all the energy I could from the
|>primary. The ratio of output vs input energy (transfer efficiency/bang)
|>could be a meaningful way of measuring how well a coil could perform. It
|>should be measurable with either a 2-coil TC or a magnifying TC.
|>
|>Assume you've done "single bang" measurements, and are able to farily
|>repeatably set your primary gap breakdown voltage via a static gap.
|>Also, assume you've
|>estimated your peak secondary voltage indirectly (via low duty cycle
|>sparklength or via calibrated pickup plate/storage scope). Assume your
|>resonator is high Q, and is heavily capacitively-loaded so that
|>virtually ALL of the resonator's energy will be stored in the toroid's
|>capacitance at the point of peak secondary voltage. [Since most of the
|>secondary's self- capacitance is concentrated towards the bottom, we'll
|>choose to ignore it in this analysis - this only makes our analysis a
|>little bit more pessimistic].
|>Finally, lets assume that we quench the gap at the end of the first
|>beat.
|>
|>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%...  No flames today Robert, you're
|>certainly within 10 db   :^)
|>
|>Now, I realize that I've made LOTS of assumptions above. Once we get
|>breakout, the secondary output voltage and Q will both decrease.
|>However, its not clear that these changes would cause a dramatic
|>fall-off in transfer efficiency from the single-shot case. In fact,
|>after breakout, when the secondary Q drops to a level closer to the
|>primary Q, the energy tranfer efficiency might actually improve!
|>
|>- Am I all wet?
|>
|>- What do you get when you plug in _your_ coil's parameters?
|>
|>As usual, throw any extra Joules my way...
|>
|>Safe, and maybe even higher power, coilin' to ya!
|>
|>-- Bert --
|
|
|Bert,
|
|I think that calculating the power on the primary side, and then
|working the output power on the secondary by 1/2 [C(V^2)] on the
|topload capacitance and then getting an efficiency of conversion
|where the 'twains meet' is an interesting simplistic way to compare
|systems.  Unfortunately I have no firm number for the capacitance of
|the topload on MTC or the length of a single shot breakaway streamer,
|and therefore the discharge clamp limiting voltage value for my
|topload.  These are measurements I hope to conduct at the new lab.
|
|BTW, you used 20 kV/inch for your voltage guestimation.  According to
|the famous paper by Clark and Ryan the value is more like 48-52
|kV/inch between sphere gaps. Trouble is, all sorts of factors
|influence this measurement to make it almost meaningless in the field
|(pun intended!).   Carefully controlled conditions must be set up to hope 
for
|any accuracy when attempting to measure voltages by spark length.  I have
|plans
|to build a directly connectable HV capacitive divider probe this year
|for the lab with a capability of at least 500 kV with accurate
|frequency response for waveform analysis.  This will be a very useful
|instrument with which many questions might be answered.
|
|BTW, I pulled some numbers out of thin air for MTC (1.2 megavolt
|breakaway [60 inches -at- 20 kV/inch] and 50 pF topload) and got a really big
|output Joules which was about double my input power.  I've got to go
|write a post now which will give me instant celebrity status over at
|the free energy camp.
|
|Thank's for your input, as always.
|
|regards,
|rwstephens
|