MMC Thoughts

• To: tesla-at-pupman-dot-com
• Subject: MMC Thoughts
• From: Gwyn Zucca <gwyn-at-tcbod.demon.co.uk> (by way of Terry Fritz <twf-at-verinet-dot-com>)
• Date: Mon, 12 Apr 1999 21:51:04 -0600
• Approved: twf-at-verinet-dot-com

Hello all MMC builders,


Having followed the MMC thread, a few thoughts occur to me.


Caps manufactured by Wima, Evox Refa, Philips all offer high pulse types
with large dV/dt ratings.

As long as the individual unit current handling capacity is not
exceeded, there should be no problem as has been pointed out this can be
derived from dV/dt * C.

Taking the peak tank current as V peak / tank circuit surge impedance...
Sqrt(L/C) + a few ohms for the spark gap say 10 ohms,
then you need enough parallel chains to handle this current.

There should be sufficient caps in series to cope with the peak
voltages, allowing some de-rating for frequency, at 200Khz this could be
down to around 25-30% of the DC rating of the capacitor.

A good series - parallel connection grid to reduce stray inductance,
minimise ESR and reduce the possibility of HF parasitics.


I have looked at the data in the catalogues of the easily obtainable
caps provided by the manufactures above and providing that the 
individual capacitors are operated within the parameters set down by the
manufacturer, pulse caps built using the MMC method should prove trouble
free, the only problem being finding the units at a sufficiently cheap
price given the numbers required to build 
appropriately sized pulse caps.

I myself am getting fed up with the time, effort and cost involved in
making decent rolled or flat plate pulse caps under oil, I have been
considering building a couple of large MMC units for use with my
Magnifier system under current development



Cheers

Gwyn D Zucca, ENGLAND

• Prev: Spark gap sim, method revealed
• Next: Re: Rolled PE Caps
• Index(es):
  • Main
  • Thread