Date: Mon Oct 27 21:18:36 2008
Author: William Beaty
Subject: Re: X-Rays Detected From Scotch Tape
On Mon, 27 Oct 2008, Bernard Cleyet wrote:
> I attempted a measurement w/ a Keithley ionization chamber -- no luck
> because, as posted by CP, EMI masked any possible ionization.
> Description of such lamps: (note 2=>5 kV.)
A particular kind of common high-vacuum light bulb pulsed at >10KV gives
soft x-rays easily detectable by an alpha-window GM counter. If your demo
equipment includes a handheld Tesla coil with an Edison socket attachment,
try running it with a long "aquarium" or "exhibits case" light bulb.
These bulbs are usually evacuated rather than argon-filled. Argon filled
bulbs produce violet plasma fingers when attached to a Tesla coil, while
aquarium-bulbs give a dark space with flashes of glass fluorescence blue
or green. Cover the bulb with grounded Al foil to increase the x-ray
output. Use Radio Shack burglar alarm window adhesive foil tape (Pb foil)
to shield these bulbs while leaving a side window.
X-rays and light bulbs
Also, here are papers which found significant x-ray output from small
plastic chambers at 1e-2Torr with only a few KV power supply.
A simple x-ray emitter Kawai 2005
Terasawa-type small X-Ray Gas Tubes and..
Strong X-Ray Emission from Electrified Insulators 2005 Inada
> A DIYer's site (tech. detail)
> one quote ~ Tesla found best p. is 250 mm/Hg. Above gives 2=> 7 milliT.
> MFP calculadora:
> bc would appreciate the fluorescence result
> p.s. note the A is 1/4 as the electron is a point compared to the
> molecules. And a rather short MFP will work, as the distance from
> the wound tape to the unwound is very short, IIRC, < a few micrometer.
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William J. Beaty http://staff.washington.edu/wbeaty/
beaty chemwashingtonedu Research Engineer
billb amascicom UW Chem Dept, Bagley Hall RM74
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