Friday, September 11, 2009


I am starting to realize just how involved this little micro-Marx generator I'm building really is. That is, if I want to do it _right_.

Kindly indulge me while I polish up this dusty old thing called my ego. 

I can do this Marx thing "right now" (well, not really, but fairly soon) or I can do it "right". By doing it right, I believe I will be the first amateur to build a "fast" (that is, sub-100nS) Marx. 

Anybody who can solder can string together some resistors, capacitors, and bent bits of wire for spark gaps, and make big sparks. The rise times will be on the order of uS, and the rise and commutation times will be scattered statistically all over the place. (this phenomenon is known in the vernacular of the business as "jitter". Are you taking notes kids? There will be a quiz.) But the people who are achieving rise times anywhere below 1uS, with low jitter, those guys are scientists. They've got PhD's and budgets.

And I am hardly a past master at this stuff! I have constructed precisely two spark gap switches in my life time. The recent one, and another, more ghetto construction I built around 1986, based on a design from good old Bob "Information Unlimited" Iannini. I think it's in that first book of projects he wrote but I'm too lazy to go look it up right now. I might have bought the plans from his mail-order business. Only pictures and a few parts from it remain today. It was nothing to be proud of.

Some twenty three years passed between the two projects, during which I did a great deal of reading on the subject.

I think the new switch, if not yet, will soon be something to be proud of. But in order for it to be "something to be proud of", it has to be demonstrated to do something above-n-beyond the switches that other amateurs have built lately. At least one of these - a rather good looking design by a fellow in Canada - has experienced a casing failure.

Oh, and have I mentioned that when this project is complete, and I've figured out wherever the upper boundary for charge transfer is on this switch, I will possess TWO very high powered, very fast switches? The other is a so-called "rail gap switch" in that its electrodes have a linear rail-like geometry.

There are projects one might consider doing with double-pulse machines.

Does anyone know where I could pick up a neutron detector, cheap?  Or a really good backstop for 10.6ยต light?  Naahh, you don't want to know.

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