Re: [TCML] Life Magazine historic photo archive

[William Beaty <billb@xxxxxxxxxx>]

On Thu, 27 Nov 2008, David Rieben wrote:
> I believe that is actually an inclosed Van de Graf
> generator. That does look like a primary coil that
> the technician is standing on, though doesn't it?

Definitely a VDG, or more likely a VDG-powered linear accelerator with the
drift tube inside.  You can see a belt-drive motor in the second photo.
The vertical tube is surrounded with separate metal rings.  In operation
these rings become charged via leakage, forming a sort of voltage-divider
effect which eliminates the 1/r^2 field and instead gives a very linear
field between the top terminal and the grounded base.

Also, it's not a vacuum tank.   VDG particle accelerators achive higher
voltage than in air by being operated in high-pressure tanks.

That "primary coil" is strange.  It no doubt serves as the ground plane at
the coil base.  But why a spiral?  Maybe someone realized that it's
lighter and cheaper than a machined slab.  It's not a new invention, since
I've encountered photos of large DC HV sphere terminals formed from
spiral-bent pipe rather than metal-spun sheet.



> I have seen other images of this same piece and
> I believe it was identified as a VDG.
> BTW, did anyone notice the "ghost" painter
> piering down at the technician in this photo?
> http://images.google.com/hosted/life/f?q=high+voltage+source:life&imgurl=bda8429bbe7891df
> David Rieben

(((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))
William J. Beaty                http://staff.washington.edu/wbeaty/
beaty chem washington edu       Research Engineer
billbamascicom                  UW Chem Dept,  Bagley Hall RM74
206-543-6195                    Box 351700, Seattle, WA 98195-1700
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