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Hand-Cranked X-Rays

September 8, 2009

xray_apparatus A hand-cranked Wimshurst static generator, coupled with a modern-production “magnetic effect” Crookes tube, can produce just enough x-rays to make useful digital radiographs and excite Geiger counters.  The Wimshurst machine and the discharge tube can be readily obtained from online retailers in educational science apparatus for as little as $120.  To make radiographs, I employed a 6-inch fluoroscopy image intensifier tube with a custom mount for my Canon S3 IS digital camera.  All photos in the following gallery were 15-second exposures with moderate hand cranking.

Magnetic-effect tubes contain a slotted cathode that allows a beam of electrons, formed in a high-vacuum glow discharge, to impinge upon a phosphor screen at near-anode potential.  In the classic usage, the experimenter observes deflection of the electron beam when a magnet is brought near the tube.  The only contemporary American manufacturer of a magnetic-effect demo tube, Electro-Technic Products Inc., was enjoined from offering the product on the domestic market precisely because of x-rays.  So tubes of this type available in the US are invariably of Chinese or Indian manufacture—all the better because they’re cheap.  I bought mine from www.sci-supply.com for $79.95.

So what’s the possible utility of this?  Radiography in third-world outposts with no electrical supply?  Hardly…the image quality is too poor, 15 seconds too long for practical exposures, and ever since the vacuum tube went the way of the dinosaur it’s been easy to get enough power from batteries to energize small, intense, pulsed cold-cathode x-ray machines.  But the novelty factor is nice, and in museums or other didactic settings, the literal hands-on nature of this x-ray apparatus should be appealing.

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Fingers of a 28-year-old male hominid.  This hominid’s other hand was busy cranking the Wimshurst to power the tube for the exposure.  Field uniformity is poor, and the source-to-detector distance is a mere six inches–but contrast is OK and this is a perfectly serviceable human radiograph.  Exposure was approximately 100 μR.

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PVC and polyethylene hoses of the same size (left and right, respectively), vividly illustrating the x-ray attenuating power of the chlorine in PVC.

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Electronic stopwatch. Decent detail, including individual wires, can be discerned.  Remember, the x-ray source is a Crookes tube, not a modern line-focus x-ray tube!

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Iodine tincture (a few percent iodine in alcohol) from the drugstore is black to x-rays.

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Geiger tube from a CDV-700 civil-defense Geiger counter.  Prominent features visible by x-ray include the thin beta window in the middle of the tube’s active region, and the thin anode wire running down its axis.

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A hand tap set contained in a plastic box. No big surprises, but the taps are slightly magnetized and some resulting warpage of the image-intensifier output can be seen.

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The handle of a cheap steak knife, showing how the blade is anchored into the plastic.

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Package of “AA” lithium batteries.

9 comments

  1. Your little image intensifier is almost more interesting than the x-ray source. One question- Why is the camera mounted in line with the II instead of off to the side with a mirror as is typical with fluoroscopic units? Taking the camera out of the path of the x-rays could reduce noise. I’m not sure how much exposure reaches the camera, though, so it may be insignificant.
    Does the image brightness becomes more uniform when the x-ray source is moved farther from the II? Meaning- Is the center brightness due to the image intensifier or the inverse square law?

    Cool trick


    • Hi Ryan! The II tube is a Precise Optics PS-61 that I obtained on eBay, new in the box. I actually see lots of these on eBay, though most are heavily used and have screen damage. For simplicity, I don’t use a mirror, and the glass in the camera lens is sufficiently thick to prevent a lot of noise. A longer source-to-detector distance indeed improves the uniformity of the field at the expense of intensity. One of these days I may post some other pics made with this II—some autoradiographs of radioactive items, some radiographs made with Am-241, etc. How did your dissertation proposal go?


  2. i have a big old russian night vision tube(greenphosphor) and i was thinkig about puting a x-ray tube infront of it.What do you think will i be able to see anything?


  3. Hi, can I use your idea to try to win this contest? I’ll cite you as a source.


    • What contest?


      • I’d rather not post it live on your page in case someone else wants to use this idea. I can email it to you.


      • Okay, you can email it to me.


  4. email sent


  5. So I posted a comment & you got back to me in literally 2 minutes but I sent you an email & haven’t heard back. No worries, I’m assuming if you weren’t cool with it you’d say something. Cheers mate.



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