Re: [TCML] Maxwell #31915 colossal pulse caps

["DC Cox" <resonance@xxxxxxxxxxxx>]

Dave

Just give a call to GA and ask for Bob Cooper.  He's a friend of mine and
the senior design engineer for Maxwell.  His mother lives in Tucson and our
paths cross occasionally.
Bob can give you the exact scoop as he designed the caps you are using ---
he's been with Maxwell for nearly 35 yrs!  He knows the curves in his head.
An amazing character.

Tell him I said "hi".

D.C. Cox




On Thu, Aug 14, 2008 at 3:38 PM, David Rieben <drieben@xxxxxxxxxxx> wrote:

> Hi all,
>
> I am now the proud papa of 3 newly acquired Maxwell #31915
> 100 kV, .44 uF (that's right --  440 nF!) pulse caps with one
> more on the way ;^)). Here is an eBay listing of one of these units:
>
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360079598908&ih=023&category=4662&ssPageName=STORE:PROMOBOX:NEWLIST#LIST
>
> They are of a pretty rotund design with dimensions of 4" x 6"
> x 29" long and weigh just over 32 lbs. each. Although I can't
> seem to find an exact part number match, I was able to find
> some specs from GA's current line of pulse caps that did
> seem to have a pretty close match to these. I looked up on
> General Atomics' (since GA bought out Maxwell) webpage
> for some specs on these on the closest cap in the way of
> voltage, capacitance and physical dimensions and found:
>
> http://www.gaep.com/series-s-ss-capacitors.html
>
> Notice the #31427. It is of the same size physical dimensions
> and weight as mine and has a nearly identical voltage/capacitance
> rating of 100 kV @ .4 uF. Notice though that it is rated for 1 pps ap-
> plication and is only rated for a 15,000 shot life. However, I am
> thinking of someday seriesing 2 or 3 of these units for a super
> Tesla coil cap in the .16 to .24 uF range. It seems to me that
> with a 200 or 300 kV ceiling voltage rating, these should be pretty
> much bullet proof in a large Tesla coil circuit, even with very re-
> latively high primary voltages, say 40 kV or more, since the shot
> life expectancy goes up almost logarithmically in proportion to a
> decrease in the applied voltage, doesn't it? Maybe Bert Hickman
> or Antonio Quieros (spelling?) could clarify here. (hint --- :^)
> I suppose about the only other possible limiting factor would
> be the RMS current levels.
>
> Also, the "measured C" that's on the label is generally about
> .48 uF for each cap and my measurements of them so far
> has verified a pretty close match - probably measures out to
> around 8 to 12 nFd less than what the label says.
>
> Anyway, tell me what you all think.
>
> David
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