Journalist Gets Blasted By the Pentagon's Pain Ray — Twice 357
dsinc writes "Wired's Spencer Ackerman voluntarily subjected himself to what the U.S. military calls the Active Denial System, an energy weapon commonly known as the 'Pain Ray' that turns electricity into millimeter wave radio frequency and blasts targets with heat. He describes it thus: 'When the signal goes out over radio to shoot me, there’s no warning — no flash, no smell, no sound, no round. Suddenly my chest and neck feel like they’ve been exposed to a blast furnace, with a sting thrown in for good measure. I’m getting blasted with 12 joules of energy per square centimeter, in a fairly concentrated blast diameter. I last maybe two seconds of curiosity before my body takes the controls and yanks me out of the way of the beam.'"
The device has been tested now on over 11,000 people, with only two serious injuries to show for it. However, the device has limitations: rainy weather decreases its effectiveness, and its "boot-up" time is 16 hours, making it useless for breaking up unexpected, impromptu mobs.
Re:16 hours? (Score:4, Informative)
Getting that much energy stored up and ready for use at 12 joules per square centimeter might be the reason, especially when you take efficiency losses into account.
Corner reflector (Score:5, Informative)
If you ever go to a protest where you expect the government to use one of these on you, bring a buch of corner reflectors. [wikipedia.org]. They can be bought in boat stores, or made cheaply out of paper lined with aluminum foil, and they will send the "pain ray" right back at the operator.
Re:16 hours? (Score:5, Informative)
Why something that just pumps out such large amounts of juice needs that long a startup cycle though, I have no idea. My best guess is limitations on the components themselves. Maybe the energy storage elements suffer from charging too quickly, or maybe it has to store plenty of energy in advance to maintain a full-power beam over extended periods of time.
Re:Uh, what (Score:4, Informative)
That is a pretty common time for cooling down to liquid nitrogen or superconducting temperatures.
Re:future weapons ? (Score:2, Informative)
Umm, no it's still in the past; we just have to wait until we get to see it.
Re:16 hours? (Score:5, Informative)
Re:future weapons ? (Score:4, Informative)
Re:16 hours? (Score:5, Informative)
This is CW Microwave at 95ghz so I'd imagine it takes that long for everything to charge and come into spec frequency-wise, since all of the waveguides and antenna would be very sensitive to SWR if the frequency drifts too badly .. probably to the point of destruction at 100kw PEP.
Close not exactly. The highest freq amps I've worked on are just above Ku band and the highest power is a KW or so, so I'm about a factor of 4 low in freq (which in microwave work is practically in their backyard) and low by a factor of 100 in power (which is a big difference).
Waveguide and antenna for microwave work are pretty much inherently broadband. Unless you're doing it wrong or weird darn near 2:1 is normal. Its not the antenna and waveguide. Combining networks are pretty precise ... wavelength at 100 ghz is what 3 mm or so, so you'd like to build them to a hundredth or better of that, or about 0.03 mm accuracy which isn't all that taxing for a machinist. The point being that its probably not realistic to build something that requires 12 sig figs of freq accuracy if you can't build anything to more than maybe 5 or 6 sig figs of wavelength accuracy even in theory.
I can purchase off the shelf GPSDO with frequency accuracy better than 10e-11, even better than 10e-12 on a good day, also rubidium oscillators are not that bad. You can build one that takes "16 hours" or whatever to stabilize. Like I figured out above, you can't build an antenna that depends on 11 sig figs of freq stability (this is required for comm purposes, not required to just blast watts downrange to torture people).
A normal person would engineer in a really good quartz crystal oscillator probably a TXCO which unlike the non-temperature stabilized dip oscilator in you PC that wanders 50 ppm or so, the txco is probably pretty stable to 0.1 or so ppm, or 10e-7, which is better than you can build your wavelength dependent components, so.. also it "boots up" in less than a second.
The puzzler for me is at 100 GHZ you're gonna use WR8 or WR10 and those do not tolerate more than 10 KW or so before arcing over. High freq = small wavelength = small waveguide = short distance for arc to zap across. My guess is they're using an array of like 10x10 or 100 little 1 KW blasters. Some brave OWS protestor or Ron Paul supporter should walk in front of the beam and see if its got the beamwidth characteristics of an antenna a tenth the size.
From having been in the Army reserves two decades ago I can guarantee that the army tech manual for my unisys strange btos minicomputer thingy for ammo accounting probably said it can be unpacked, hooked up, restored from backup, tested, blah blah in 16 hours, but in practice, in sane and normal weather and sane and normal conditions we could set up in like one hour or less including running comm cabling for the remote terminals and test suites and everything. But, yes, airdropped into Antarctica with new/untested/not-pre-setup gear and all noob staff doing it the first time "for real" outside of AIT I could see Fing around for 16 hours. I remember at AIT having to do this one inventory operation that was pretty tricky and they gave us 4 hours and I did it in about 45 minutes because I knew what I was doing, but some hopeless cases took darn near the whole 4 hours.
Re:16 hours? (Score:4, Informative)
WR8 and WR10 are standard waveguide sizes not transistors. I guess you'd say its sort of the microwave RF equivalent of singlemode optical fiber.
Like down around 10 GHz you use standard size WR90, etc.
The waveguide wouldn't arc over if you increase the dimensions... however that increases the wavelength the waveguide operates at such that it would no longer be 100 GHz waveguide it would be 50 GHz waveguide or whatever.
Waveguide is singlemode, obviously (?) over a bit less than a 2:1 wavelength range.
You can theoretically run multimode, after all waveguide is high pass (hold a piece up in the air and look thru it...), but thats... considered kinda crazy. Crazy enough to work, maybe, if you spent enough money modeling it. Have to think about that. I bet someone is making a fat stack of cash off this crazy thing.