Ukranian guys have fun directing microwave beams out of the oven


#1

[Read the post]


#2

Let it explodes, boys. Let it explodes.


#3

Great, now I’m not going to be allowed to take my microwave on an airplane.


#4

From the shelling and bomber background noise, I’d say playing with an open mw oven is not the most dangerous thing right now.


#5

In Russia waves guide you!

…but hey, two points for at least thinking of a wave guide…


#6

I’m bemused that this is the counter-evidence against the fine fiolks that don’t use microwave ovens for fear of the cancer.


#7

Coffee can??!? Everyone knows that a Pringles can is the correct diameter to make a 2.45 GHz circular waveguide!


#8

Are these the same guys that did the Coke and butane trick a few posts back?


#9

Wow… you totally missed the golden opportunity to get “death ray” in the headline. You’re slipping, BoingBoing.


#10

I was always partial to certain shapes of coffee cans since they had similar ratios but real metal walls.


#11

Now I’m getting excited for Fallout 4.


#12

For your health!

(holy crap. wildly unsafe microwave play with bombs going off in the back)


#13

No, that’s just inaccurate. This would be a Death Wave, not ray.


#14

Let’s explore the Death Wave/Death Ray duality.


#15

If we add five points to it can we call it a Death Star?


#16

Yes, but they were introduced as Russians.

eta: found it


#17

Well, to be fair, it’s not really safe to live in any of the former Soviet republics, at least not from a western frame of mind.

These guys can point to Chernobyl and say “yeah, whatever.”


#18

Extremely unsafe, regarding vision. Microwaves are absorbed very efficiently by your retinas, and they don’t produce a blink reflex because they aren’t visible light.

It is extremely easy to blind yourself or other people with microwave emitters. Please don’t play with them.

(Although I’m genuinely surprised that there hasn’t been at terrorist use of magnetrons as a mass maiming/blinding device. Inverse square laws work in our favor that way, I suppose.)


#19

Inverse square law. This is a piddly kilowatt. Just do not look up close into the waveguides.

Chernobyl wasn’t that bad.

I once calculated the dangerous distance from a 800-watt 2.4GHz isotropic emitter. It’s somewhere on hackaday.com comments. #3 here.

Cut/paste for your pleasure here:


Legal schmegal – even if it may be illegal it is illegal only when you get caught. Let’s look at the numbers.

Let’s assume the magnetron radiates 800 watts in an omnidirectional way as a point source. (I know, I know, “let’s assume a spherical horse”.) Let’s assume the harmless power density for nonpermanent exposure is 5 mW/cm2 (allowed mw oven leakage is 5 mW/cm2 at 5 cm from the surface).

The actual safe power densities for short-term exposure can be pretty higher. Tissue damage occurs at 42 ‘C, penetration depth for 2.45 GHz where half the energy is absorbed is about 2 cm, we can approximate the heat capacity of tissue to be equal to water (4.2 J/gK); let’s assume 30 second exposition, 100% absorption in first centimeter of the tissue, no heat losses. Heating a cubic centimeter of water by 5 degrees requires 21 joules. To heat a 1 cm layer of water by 5 degrees over 30 seconds takes 700 mW/cm2. For 10 seconds it is 2.1 W/cm2, for 2 seconds it is 10 W/cm2.

(The actual absorption in the tissue depends on the tissue character. Fatty tissues will absorb less energy than water-rich ones (e.g. muscles). The heat capacity of tissue is lower than of water, but in reality there will be heat losses to the surrounding environment and to deeper tissue levels.)

The surface of the sphere is calculated as 4pir^2.

At 10 cm distance the power density is 630 mW/cm2.
At 25 cm it is 100 mW/cm2.
At 50 cm it is 25 mW/cm2.
At 75 cm it is 11 mW/cm2.
At 100 cm it is 6.3 mW/cm2.
At 115 cm we are at 4.8 mW/cm2, below the power leakage limits considered safe by cover-your-ass govt standardization body.
At 253 cm we are at 1 mW/cm2, a level considered safe.

This however assumes homogeneous field and no reflections. (In the oven cavity the radiation is reflected from its walls so the power is not lost so easily.) Also any sort of an antenna will focus the beam and lower the amount of losses in that direction (and increase it in others, according to the antenna’s pattern). Conductive objects can also transfer the energy along with little losses and reradiate it or couple it to other objects. So there are caveats for the actual experimental setup.

I’d say that the actual danger is in the very vicinity of the magnetron and, more than that, in the high voltage capacitor. (BEWARE of that one, it packs a nasty punch.)

Somebody please validate my calculations, as they are just an irritated back-of-the-envelope scribbling. However at the first glance it does not seem that, while not entirely safe, the danger of such experiments is somewhat below the sky-is-falling level of the local Wussy Brigade noisemakers.


#20

very true.

but one high risk doesn’t neutralize another, a second high risk factor still increases your risk level, the only difference is your baseline risk assessment level increases when you live with constant danger.

that being said…these guys seem smart enough to know what they are doing so it seems riskier then it actually is, microwave radiation disperses in nanoseconds so unless you directly fry some part of yourself then the risk is minimal.

yes, those people are the real nuts.