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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Home brew linear accelerator?
References: <3D8B60B3.1090107@BOGUS.earthlink.net> <3D8C1E99.74B9964D@earthlink.net>
Date: Sun, 22 Sep 2002 13:19:18 GMT
NNTP-Posting-Date: Sun, 22 Sep 2002 06:19:18 PDT
Robert Baer wrote:
> Chris Carlen wrote:
> > Hi:
> > Every once in a while I get to thinking about the practicality of a
> > hobbyist/amateur scientist performing entry-level nuclear reaction
> > experiments with home-made equipment. Like hitting some target with
> > beta or alpha radiation by use of a small cyclotron or linear accelerator.
> > I seem to recall that the first cyclotron was hand-sized, so it seems
> > possible to make such a thing at home. I don't know if that device was
> > able to produce enough energy though, to cause nuclear reactions.
> > But another interesting memory that makes me ponder about this is that
> > while visiting a friend a few years back who had worked on medical
> > radiation therapy equipment, in which small linear accelerators were
> > typical, he showed me a very beautiful piece of "art."
> > This was a square lucite block about 4 inches square with a three
> > dimensional tree carved out internally, by tiny silvery channels. The
> > intricacy of the tree was astonishing, and clearly it was not carved out
> > in the typical sense.
> > How was this effect created? My friend told me that when repairing the
> > linear accelerator machines, they would take the opportunity to place a
> > clear plastic block in the beam path. They would hammer it with
> > electrons for a while (at least I think they were accelerating
> > electrons, as they are quite easy to come by).
> > After some time, the block would be charged with a very hefty charge.
> > They would then take a grounded metal screwdriver and just touch it to
> > the block, which would cause the charge to emerge from the block at the
> > point where the contact occurred. This would create the carving out of
> > the tree, with the "trunk" of the tree being formed where the
> > screwdriver was touched.
> > Has anyone ever seen such an effect, or had experience with this sort of
> > high energy fooling around? It sure sounds like fun to me! :-)
> > I wonder if such an accelerator could be made by a serious hobbyist?
> > One thing that really puzzles me is how an e- beam would behave in
> > atmosphere. Obviously, it can't propagate for a long distance, and I
> > would expect that the distance would depend on the energy. How many eV
> > are needed to make it a few inches? What sort of window would be used
> > to pass the beam out of the vacuum region?
> > Comments appreciated.
> > Good day.
> > --
> > _____________________
> > Christopher R. Carlen
> > firstname.lastname@example.org
> > Suse 7.3 Linux 2.4.10
> I personally know someone that did that; up to 4MEV linear pulsed
> Used the long fluorescent tubes seen in industries for the vacuum pipe
> (phosphorous removed, and chemically cleaned inside). "Drift" rings to
> equalize voltage along the length via 1/2 inch wide aluminum foil glued
> on outside, machined plates epoxied on the ends of the glass for joining
> tubes together; total length roughly 70 percent of the length of a
> standard garage (where it was built).
> A rather large and old GE X-ray transformers was used to generate the
> high voltage; a capacitive bank (at some high voltage, do not remember
> how much) was discharged into the primary and the secondary was used to
> drive the accelerator.
> What was done for waveform damping and impedance matching (if any) i
> cannot say, as i had nothing to do with the overall design or the
> But i understand that one can do some interesting low energy
> experiments with 4MEV as the approximate limit.
> You can make a lead beam dump to measure the actual energy; a pulse or
> pulses captured by that would give it a charge that can easily be
> measured, giving some means of calibration.
> A slush pump and liquid nitrogen trap for continuous pumping was used
> to make it viable; that glass is rather porous at reasonable vacuum
The glass hardly leaks at all. Vacuum tubes made 70 years ago still
work. The leaks were due to the epoxy. A good example of this problem is
laser tubes. The original epoxy seal tubes had a life of a couple of
years whether they were used or not. The hard seal tubes can last for
many years. I have some hard seal laser tubes nearly twenty years old
that still work.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com
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