In recent years, several works of fiction have featured “UV flashbangs”*—small devices that, when triggered, produce a brillant flash of ultraviolet light, similar to a conventional “flashbang” stun grenade.
Now, from what I’ve read, an M84 flashbang uses a charge of 4.5 grams of magnesium and ammonium perchlorate, which produces 6-8 million candela.
Assuming that this doesn’t already produce an equivilant amount of UV, I’m just wondering if there’s any chemical reaction that can—in a comparable amount of time with something approaching a man-portable amount of materials?**
*Three guesses on what kinds of flicks these were.
**This is also leaving aside the question of if this would produce as much UV as, say, normal sunlight at high noon, or at least morning. Mostly because I couldn’t find the numbers. Someone else might have better luck, though.
Burning magnesium does produce a quite significant amount of UV – enough to cause a “sunburn” in a minute or so
I’ll look up links if you need more than my say so (and you should) but need for UV protection is well-noted in (e.g.) specialty welding manuals. It’s also worth noting that any substantial thermodynamic (vs. spectral) emitter of UV will release more energy at lower (visible) wavelengths – and those are all we will see, as with the sun [whose corona has a temperature of ~6000° C, IIRC, but it’s apparent photographic “spectral temperature” can be ~6500-6800 °C, partly due to spectral truncation by the visible range]
And I’d known a little about the UV produced by some forms of welding—mostly after reading about “arc eye”—so would you definately say that I’d be better off trying to produce huge flashes of UV by purely electrical means? Some kind of Xenon flash lamp looks promising, from what little I’ve read.
I’m confused – what would the purpose of a UV flashbang be? I thought the flash was supposed to dazzle the senses of the person it’s being thrown at, giving the police (or whoever) time to move in and apprehend them.
Unlike Ranchoth, you’re lucky enough to not have a vampire problem.
More seriously, Ranchoth was probably asking about the real-world feasibility of the UV flashbangs seen in the movies.
Yeah, I understand, but … oh, wait, I see what you (and the “Three guesses what these types of movies were” in the OP) are talking about. A UV flashbang would be pretty useful against vampires (assuming it’s the UV in sunlight that they’re vulnerable to, like in Blade).
Never mind, folks, move along, nothing to see here.
Well, you can refer to a vessel in which a chemical reaction takes place as a reactor. IIRC that’s the usual term for any kind of process chemistry, actually.
Nitpick: The corona has a temperature of millions of degrees, but it’s very diffuse, so it can only be seen through narrow-band filters or when the main disk of the Sun is blocked out (as in an eclipse). What we see easily is the photosphere of the Sun, which has a temperature in the vicinity of 6000 C, as you said (though I think it’s actually a bit lower than 6000, not higher… The number 5770 K sticks in my head).
It’s somewhat of a mystery why, exactly, the corona would be so much hotter than the photosphere underneath it. Most of the explanations involve energy transfer through magnetic fields (especially a process called “magnetic reconnection”), but there are still a lot of details to be worked out.
