It seems like it should due to bremsstrahlung, since we're talking about electrons with 5-7KeV of energy slamming into the walls of the device, but I've found no information about this online, so I'm assuming something else must be happening. CRT-style TVs and computer monitors both have this problem, so my guess is that most of the energy is being bled out of the electrons to form microwaves. Am I right?

Also, what happens to the production of microwaves as the magnets on the magnetron slowly lose strength?



Just a google search for "magnetron x-rays" yields quite a bit of information. From this data sheet:

High voltage magnetrons emit a significant intensity of X-rays not only from the cathode sidearm but also from the output waveguide. These rays can constitute a health hazard unless adequate shielding for X-ray radiation is provided. This is a characteristic of all magnetrons and the X-rays emitted correspond to a voltage much higher than that of the anode.

A quick further glance seems to show that the penetration depth for x-rays into most materials at 7keV is dismal.

  • $\begingroup$ Thanks, I should have specified in my post that I was strictly interested in lower power ones you might find in your home - the datasheet you linked to is for a 1MW magnetron. I guess we can assume some x-rays, but very few are created and most are absorbed (although the data for attenuation depth seems like it should be a lot longer based on some of the things I've read. Most of this is new to me, so I've probably made a mistake somewhere...) $\endgroup$ – Joel Feb 4 '14 at 1:26
  • $\begingroup$ This is what's throwing me off. It seems to be saying that iron does almost nothing for low energies, but that's directly at odds with your link and a corroborating page I found. Am I completely misreading this one? $\endgroup$ – Joel Feb 4 '14 at 1:41
  • $\begingroup$ What are you using as your energy and target length? 5 KeV and 1mm gives zero transmission for Fe. $\endgroup$ – lionelbrits Feb 6 '14 at 19:21
  • $\begingroup$ Hah! I think I was ignoring the units on it and typed in 5000 KeV instead of 5. Thanks! $\endgroup$ – Joel Feb 7 '14 at 0:24

NASA Armstrong avionics tech here - RF specialist. The old medical studies on RF state a safe voltage level would be below 5,000 volts for the transmitter. Above that, the possibility of parasitic X-rays increases with voltage, especially in radar equipment. From what I understand so far, microwave oven magnetrons typically need about 4,000 volts from their transformer to oscillate, so it is within the safe range.


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