Re: [TCML] BIG solid state

[Jim Lux <jimlux@xxxxxxxxxxxxx>]

On 6/18/11 12:16 PM, Greg Leyh wrote:
> > From: Steve Ward<steve.ward@xxxxxxxxx>
> For years I had resisted the notion that a larger toroid improves spark
> length, since Conservation of Energy clearly dictates that a larger
> toroid must necessarily lower the output voltage. However, live arc
> msmts on Electrum in 1998 revealed the strong presence of large, fast
> transients, possibly indicating an arc growth mechanism analogous to
> dart leaders. In this light, a local, low impedance reservoir of charge
> might be very important indeed. In the end, the larger toroid did in
> fact improve the arc performance.


That is what I think.  The spark growth mechanisms described in B&R 
would need such a reservoir with low inductance to be able to feed 
charge when it's needed.

Ever since I saw enormously long (drawn) sparks with relatively low 
voltage (60 kV or so) at the Deutsches Museum, I realized that huge 
secondary voltages aren't a precondition for long sparks.  yes, if you 
want that fast "snap" kind of spark, but that's only going to come from 
something like a Marx.



> > There really weren't any big technological hurdles in the building of
> > this
> > DRSSTC, though I have been working extensively with this topology for the
> > last 6-7 years or so, this was merely the next step up in size (the
> > details
> > of the electronics are pretty well understood by now). With no specific
> > project schedule, i pondered the quad primary drive for about the last 2
> > years, which in my opinion is the only "new" thing going on here, and
> > even
> > that seemed too easy once it was actually implemented. De-bugging took
> > just
> > a few hours.
> >
> > The main thing preventing it from happening for so long was really just a
> > lack of man-power. The scale of things was just beyond what i could do by
> > myself in the garage. Getting people together to work on projects is
> > always
> > harder than it should be, especially when there is no deadline involved.
> >
> > Steve
>
>
> Coil logistics seem to scale roughly with the volume of the secondary;
> perhaps someone should come up with a scaling law for that. -GL


yes indeed..

There's a big difference between a "tabletop" scale where you can throw 
it in the back of the car, schlep it on a cart in one trip, etc.

And then, the basic "gotta make multiple trips, but you can still do it 
by yourself"

And then the, "need multiple people to put it up, manhandle the 
transformers, etc." but still able to be done without machinery

And finally, "needs a crane, cherry picker, or clever mechanical stuff"


The bigger it gets, the harder it is to "just fool with it for an hour", 
because it's a multi hour setup and teardown time.


Somewhere in the middle of this list, it moves from the "practical to 
work in your driveway" to "need to find a place to leave it set up"

10-15 years ago, I was working on a design for a large semi portable 
Marx.  While I had access to a forklift, it was still tricky.  I was 
using those big plastic fruit bins (MacroBin is the tradename) as a 
building block at first.

The idea was to have something trailerable that could be erected and be 
30 odd feet tall and do several hundred kJ.   I had some experience with 
tower trailers for amateur radio, but that's a very different sort of 
thing.. those you can tilt and telescope.

Something like that might still work for a big portable TC.


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