Re: Info on a BIG Marx generator

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

At 12:30 PM 8/26/2004 -0600, you wrote:
>Original poster: "David Rieben" <drieben-at-midsouth.rr-dot-com>
>Hi all,
>
>Since I now have a 150 kVDC power supply (in my latest x-ray trans-
>former) I was wondering where I could find info on building a multi-
>stage Marx bank using the x-ray tranny as the HVDC source for
>charging the caps? This would obviously be a pretty aggressive HV
>project and it may take me a long time to get the neccessary parts$$
>together to build it but I was thinking that this would really be neat ;^)
>Anyway, I would need some info on the ratings of the caps, inductors,
>and resistors for this as I'm not a HV electrical engineer by trade.
>Since this would be getting OT for the Tesla list, please send any
>responses to me directly. I was thinking of 8 to 10 stages with 100
>to 125 kV per stage (Mega-volt land!!)  and at least 1000 joules
>per cascade discharge ;^))))) I have done a casual google search
>on this subject but most of the info is for really small Marx genera-
>tors.
>
>Thanks,
>David

I'll answer on the list in short, because it comes up fairly often, so 
Terry might let it pass.

100 kV charging voltages have all the problems that running your TC primary 
at 100kV would have: corona, flashovers, generally a pain to 
handle.  However, stage voltages of 100kV are very popular for large 
Marxes, for a number of reasons.

Large Marxes are mostly a mechanical engineering exercise.  They are big, 
heavy, etc. the circuitry is simple, the construction is not (unless you 
don't care if it collapses, etc.). Structural fiberglass is your friend.

Good information is available in the commercial Marx mfr literature 
(Haefely's web site has lots of informative pdf files available, if you 
register (free and instant) on-line).  Study those photos carefully for 
ideas on mechanical design.

What you want as an information source is sections of HV textbooks on 
impulse testing, since that's what they're used for.