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

[DC Cox <resonance@xxxxxxxxxxxx>]

No, they are not.

I've seen them being built in 1984 at Maxwell Labs in San Diego.  They use
alum. foil and extend the foil 2.5" out of each end.  The foils are joined
using a secret proprietary alu. soldering technique. They are also "wound"
in a clean room with the techs wearing space suits similar to Intell's chip
fab process.

They are definitely much more robust than MMC type caps and better suited to
pole xmfr applications. I've been using them since 1978 and have never ever
had a single failure.  Now we do our own high energy discharge caps and sell
them for 1/2 the price of an equivalent Maxwell cap.

Dr. Resonance





On Thu, Apr 15, 2010 at 7:52 PM, Kurt Schraner <k.schraner@xxxxxxxxxx>wrote:

> I seem to remember Maxwell pulse caps to be internally buildt as MMC's.
> Unfortunately cannot find the link to the TCML postings, which showed
> an autopsy or/and X-ray of a Maxwell cap (...by Bert H. or Terry F.?).
> Someone remembering too?
>
> I've yet some pic's of a Maxwell 37667 autopsy from Kreso Bukvic 08/04/2004
>
> Regards, Kurt
>
>
> Gary Lau wrote:
>
>> 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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