Re: [TCML] Primary Capacitance Calculations - "Black Boxes"

[Gary Lau <glau1024@xxxxxxxxx>]

I don't think that the stray lead inductance from an MMC array in any
way would impact performance.  It may be true that an MMC will have a
higher inductance than a purpose-built pulse cap, but this in no way
limits performance in our application.  If there's an additional few
nanoHenrys of lead inductance introduced by the cap leads, just reduce
your primary tap position so that the same net inductance and resonant
frequency is achieved.  Yes, the parasitic inductance is off-axis so
the pri-sec coupling will theoretically be slightly reduced, but that
too is easily compensated for (if it was significant) by lowering the
secondary.  Peak currents are unaffected.

There may be other reasons that an MMC is not the best choice for a
large coil (economics, size, labor, cost, current rating, etc) , but
please let's be accurate in citing reasons.  Now if you were talking
about ESR (Resistance), that would matter, but I've seen no data on
that.

How can you say in general terms that an MMC is rated for only 432A
Peak without stating the construction details (how many parallel
strings)?

Regards, Gary Lau
MA, USA



On Tue, Apr 13, 2010 at 12:04 PM, DC Cox <resonance@xxxxxxxxxxxx> wrote:
> Using MMCs with a pole xmfr will present problems.  Too many lead
> connections lead to high relative inductance thus limiting peak currents in
> the discharge cycle.  Also, MMCs are not designed to handle the large peak
> currents.
>
> Best to use a hi-Q factor energy discharge cap rated to do the job ----
> minimal internal connections that are accomplished with the extended foil
> design connections.  Typical is a wide foil area with very low inductance
> connections which permit high peak currents.
>
> A typical pole xmfr powered coil, operating with a .06 uF 80 kV energy
> discharge capacitor will see peak currents of 3,500 Amps (or more) in the
> discharge cycle.  Typically these pulses occur at around 400 pulses per
> second for best coil performance which again would be a serious strain for
> an MMC which is rated at 432 Amps peak (max).
>
> Dr. Resonance
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