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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