If you say that you’re “nuking” something, pretty much everyone will know that you mean you’re heating something in the microwave. It’s technically incorrect, of course, as the magnetron inside the oven emits only non-ionizing radiation, and is completely incapable of generating ionizing radiation such as X-rays. Right?
Perhaps not, as these experiments with an overdriven magnetron suggest. First off, this is really something you shouldn’t try; aside from the obvious hazards that attend any attempt to generate ionizing radiation, there are risks aplenty here. First of all, modifying magnetrons as [SciTubeHD] did here is risky thanks to the toxic beryllium they contain, and the power supply he used, which features a DIY flyback transformer we recently featured, generates potentially dangerous voltages. You’ve been warned.
For the experiment, [SciTubeHD] stripped the magnets off a magnetron and connected his 40-kV AC power supply between the filament and the metal case of the tube. We’re not completely clear to us how this creates X-rays, but it appears to do so given the distinctive glow given off by an intensifying screen harvested from an old medical X-ray film cassette. The light is faint, but there’s enough to see the shadows of metallic objects like keys and PCBs positioned between the tube and the intensifying screen.
Are there any practical applications for this? Probably not, especially considering the potential risks. But it’s still pretty cool, and we’re suitably impressed that magnetrons can be repurposed like this.
A quick superficial search didn’t reveal concrete answers either way but does the
just and ONLY react to “X-rays”? Maybe it just reacted to lower energy radiation.
40 Kv is plenty. Old analog color TVs used 20-25 Kv and put out enough X-rays to require the CRTs and other high-voltage components to be made from leaded glass.
I think most of the X-ray radiation from old colour TV’s came from the HV shunt regulator tube, if used in the design.
The regulator tubes produced enough x-rays to discolor the glass. That’s why they were installed in a metal box. They could produce even more radiation if the set was malfunctioning though.
A lot of people think all CRTs are pretty scary, when in reality most of the new(er) ones are no scarier than a toaster. The really old ones though… They could be pretty bad, for several interesting reasons
Well basically you can take many vacuums tubes and over drive the voltage in the range of 20kv+ and they start producing X-rays, magnetron is basically a vacuum tube, but normally it spits high power microwaves, iirc has something to do with the high voltage interaction with the elements of the tube. Basically an inefficient particle accelerator.
It will definitely decrease the the lifetime of said tube
Unless it’s an actual x-ray tube
perhaps not. the anode target in this case is a gigantic metal block.
Most vacuum tubes arent designed or insulated for 20kv, and don’t have the proper vacuum level, not always a complete or extremely low vacuum in every tube
The Bremsstrahlung effect will wear down the plate and anode, even in x-ray tubes made for this, the anode/plates wears out, in x-ray tubes modern ones, they even have a spinning anode/plate so to reduce wear and to increase the efficiency…
Basically Building a cathode ray tube is easiest way to make X-rays, getting the proper vacuum is another story once you hit 20kv+ any gases would interfere and ionize (basically acting like a short using a resistance)
It sounds like bremsstrahlung, which is radiation emitted when fast electrons are slowed down quickly.
Or even just change direction. In general, whenever they get accelerated. Like in a magnetron…
Yep, if an audio tube can be turned into an x-ray machine with enough volts (seen it done) it is certainly not surprising that a magnetron (a much sturdier and higher-power vacuum tube) could also be made to emit x-rays.
Bremsstrahlung is the mechanism as others mentioned. With enough of a voltage differential, the electrons are accelerated to such a speed that when they interact with the atomic nuclei in the anode they emit radiation. The energy of the radiation is proportional to the speed of the charged particle being decelerated. You can make some pretty scary stuff this way.
https://en.wikipedia.org/wiki/Bremsstrahlung
Bremsstrahlung that’s exactly what I was referring to, typically this effect happens when drive voltage exceeds about 20kv
So the phrase “Any machine is a smoke machine if you operate it wrongly enough” now has a sibling: “Anything can be an x-ray emitter with enough voltage”
“anything can become an atom smasher with enough voltage”
Could do the same with a standard flash light, my keys and a green paper. My 2 cents.
But this approach will leave you with a 5% increased chance of cancer later in life
At 40kV it is predominantly soft X-rays being generated so your body would probably absorb a lot more than transmit. If it was hard X-rays (60kV+) it would be higher transmission than absorption. So I would say that it is probably much higher than a 5% risk increase (Of course that would depend on exposure time).
pff, i have an app for that. not even a cent…
If the flashlight has an incandescent bulb and you burn out the filament and then apply enough voltage to the remaining parts, you might be able to get that to produce a few actual x-rays as well. Not what you meant but just saying
Looks like yep:
https://steemit.com/science/@proteus-h/how-to-produce-xray-radiation-using-a-salvaged-light-bulb
As far as I can tell, this is a myth. The magnetrons in a domestic microwave have never contained beryllium oxide. It’s toxic, expensive, and, most importantly, completely unnecessary here. HaD has even had this discussion at least once before, it seems.
https://hackaday.com/2019/12/05/a-magnetron-tear-down/
As an aside, Google’s ever-helpful AI response will happily confirm that microwave ovens have BeO in them when asking “microwave magnetron beryllium oxide true”. At the same time, “microwave magnetron beryllium oxide myth origin” gets it agree that it’s not true and gives a few points on where the idea came from. Very helpful, 10/10.
Beryllium oxide insulator scare is nothing more than a myth. It originates from high power radar magnetrons, which do in fact use such BeO insulators (sometimes). Microwave magnetrons never contained beryllium. They use Cr3+ doped α-Al2O3.
Nice… What does that stuff taste like
Chicken, probably?
“We’re not completely clear to us how this creates X-rays”
It’s breaking radiation, or if you like technical jargon and/or German, bremsstrahlung. Without the magnet, you’ve got electrons slamming full force (40 keV) straight into the wall of the magnetron. There, they stop. In stopping, they give off X-rays.
(Electromagnetic waves happen whenever you have big accelerations on a charged particle. You can derive the formula for it from Maxwell’s laws but it’s easier just to think of it as a whip-crack going through the electromagnetic field around the particle.)
All x-ray tubes work like this; the bigger ones use actively cooled tungsten targets, since as you might imagine, not all of the energy of the electron beam ends up in x-rays. It would be interesting to know how hot the target spot of on the magnetron gets. Hopefully he doesn’t run it for very long, regardless.
That’s braking radiation. The electron energy gets converted to electromagnetic wave when the electron is decelerated (braked), not when it gets broken on impact.
Yeesh. I knew that Hooked on Phonics craze was going to end badly.
Yeah, actual breaking radiation, like from atoms being broken by neutrons in an atomic bomb, is much worse.
Yeah you’d think they would know by now, considering how many articles there have been about somebody applying a big voltage to a vacuum thingy and getting x-rays
He removed the magnets from the magnetron, so it’s no longer really a magnetron but a vacuum tube. The magnets would normally let the electrons circle inside the vacuum. Accelerated electrons emit radiation, and going in circles is a constant acceleration. The speed of the electrons (determined by the applied voltage) as well as the strength of the magnetic field determine the wavelength/frequency, which would be in the GHz range.
Now without the magnets, the electrons are just going straight until they hit the wall of the tube. If you apply 40kV, they will gain an energy of 40keV (kilo-electron-volts), which is in the low relativistic regime (511keV/c is the mass of an electron, so it’s a bit below 10%). When they hit dense matter (the wall), they will be decelerated rather quickly – which again produces radiation. This is exactly the same way as an X-ray tube produces X-rays. The wavelength depends on the energy of the electrons and the material (how fast it stops the electrons).
I wouldn’t try this at home, at least not without doing some calculations of the dose I would expect from this and some 10x or maybe even 100x overdone shielding (since the calculations could be wrong). I am a Physicist and am dealing with radiation professionally, but I would never trust myself fully…
Not much different than the electrically-stimulated commercial X-ray machines seen in clinical settings.
Except waaaay more dangerous.
Gotta love the lack of safety. Let’s cover the power supply with a towel.
What are you the fun-police?