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Re: Fw: Arc Impedance Study - Computer Models
Hi Terry,
Reading over this reply of mine doesn't really convey
what I intended. What I really meant to say was that there is a range
of L/C charging ratios which work well with simple gaps. If the L/C
ratio falls below this, extra quench ability appears to be
proportionally needed. If one starts with NST X and sets the cap size
for mains resonance, then reducing the cap size below this requires
more quench ability from the gap.
Regards,
Malcolm
> From: Self <DIRECTORATE/MALCOLM>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Fw: Arc Impedance Study - Computer Models
> Date sent: Tue, 13 Oct 1998 09:15:42 +1200
> Hi Terry, all,
>
> > Original Poster: Terry Fritz <terryf-at-verinet-dot-com>
> >
> > At 01:12 AM 10/11/98 -0400, you wrote:
> > >Hi Terry,
> > > Nice analysis. There was one last problem. What is the best
> > >surge impedance for the primary? This is related to the many turn VS
> > >few turn primary which is related to the question: Is it more
> > >efficient to transfer the energy to the secondary system with a single
> > >soliton like pulse or to let it transfer slowly by sloshing back and
> > >forth? Would a pulse forming network delivering a precise rectangular
> > >pulse with a period just shy of one quarter of the secondary resonant
> > >period be more efficient?
> > >
> > >Barry
> > >
> > snip
> >
> > Hi Barry,
> > So... is a many-turn high-inductance primary better or worse than a
> > few-turn low-inductance primary. This is very difficult to measure in
real
> > coils since changing the primary inductance does the following things:
> >
> > 1. The coupling will change.
> > 2. The primary capacitance will increase. This will raise the primary
> > energy unless the voltage were to be turned down to compensate.
> > 3. The primary circuit resistance will change.
> > 4. The spark gap may act differently depending on how much current goes
> > through it.
> > 5. Just visually looking at the coil's streamers after major circuit
> > changes over time is not an exact science :-)
> >
> > Models, however, can easily test such a change while locking all the other
> > variables. The output of computer models is, of course, perfectly
> > repeatable and objective.
> >
> > This test assumes only the primary capacitance and inductance changes.
> > Coupling, primary circuit resistance, and spark gap effects are locked. I
> > will add a correction at the end for the difference in primary enegery
> > larger caps have.
> >
> > Primary Corrected Corrected
> > Inductance Peak Current Burst Time Relative Power
> > 25% 492 61 3.24
> > 50% 622 61 5.19
> > 100% 719 61 7.17
> > 200% 782 61 8.21
> > 400% 814 61 8.91
> >
> > So it appears that larger, high inductance primaries are better. The
> > graphs show that low inductance primaries tend to have a single burst
while
> > high inductance primaries have multiple bursts. However, more energy is
> > being delivered to the arc with the high inductance primaries. I suspect
> > the losses are killing the performance with the larger primary currents.
> >
> > Terry
>
> Agree with your analysis completely. I also have an observation to
> add: I have empirically found that the lower the surge impedance of
> the **charging** circuit, the more stringent the quench
> requirements. Speaking strictly about observed performance and not
> single notch quench:
> I run a large cap small Lp coil on quite modest primary
> voltages with a single static and get sterling performance with no
> gap cooling, airflow etc. However, running with a small cap and the
> same leakage-L limited transformer, the same gap does not do the job
> and requires the extras to perform. Anyone else found this? Resonant
> charging systems in particular seem to perform well with the simpler
> gaps.
>
> Observations invited,
> Malcolm
>