The Pentagon is adding a new compound to its pain ray. Eventually, it might help make the weapon become smaller, more powerful, and easier to deploy abroad. But for now, the U.S. military won't say much about the compound, at all.

The Active Denial System is a non-lethal ray gun that heats the outer surface of the skin – a painful but (mostly) harmless experience -– using microwaves. But the thing is a little unwieldy for battlefield use. (And let's not even get into the public perception concerns.) So we were interested to see that Active Denial-maker Raytheon was recently granted a military contract to develop a new "solid state source for use in non-lethal weapons." It relies on gallium nitride, a hard, stable material with a huge heat capacity.

A second contract, this one with Darpa, involves developing gallium nitride (GaN) as a semiconductor for missile defense radars. The GaN device looks very promising for high-power microwave amplification and will produce millimeter waves, just like the existing Active Denial System.* But the military has dropped a cloak of secrecy over the new technology.

Raytheon told me that due to the "classified nature of the program," little information is available. All the company would say was that "GaN will impact a range of military electronic systems, including communications, radar and electronic warfare."

However, the cone of silence is far from air-tight. The existing Active Denial System is a huge device that travels in a shipping container and costs millions. Elsewhere, the Raytheon press machine explained that GaN will help change that. "Our... high frequency, millimeter-wave GaN [will] provide the warfighter with a lower-cost, lighter-weight, non-lethal engagement alternative," said company exec Michael Del Checcolo.

In addition, in an interview with Mass High Tech, John Finkenaur, the Active Denial System (ADS) project manager reveals that not only will the GaN technology make the device smaller and lighter, it will also remove the need for supercooling which previously made it difficult to operate the ADS on hot days.

More importantly, using gallium nitride reduces the two-hour warmup time it takes for a gyrotron ADS to become usable after powering on.

I

don’t recall that two-hour warmup being mentioned previously -– it sounds like one of those small quirks of the system that manufacturers only drop in when they're trying to sell you the next, upgraded version.

It's another sign that the non-lethal weapons community is fixed on the idea of a skin-heating pain beam, but is not satisfied with the current technology. Gallium Nitride offers another possible way forward, on top of the sheet beam klystons and infra-red lasers we've seen previously. Different technologies may work better at different scales.

GaN technology could give us small, efficient Active Denial weapons

–- small enough to be installed as a non-lethal option in existing vehicles (lack of this technology meant the previous small pain beam built for Project Sheriff was not powerful enough). If successful, the technology will doubtless feed into the portable active denial systemprogram, adding a pain beam option to the police's existing arsenal of Tasers, pepper spray, bean bags and batons.

In the longer run, the technology will also have many other spin-offs -– advanced sensors using millimeter-wave radar, more compact communications with longer ranges, and even domestic applications. In

1947, the original microwave ovenwas a spin-off from Raytheon's radar (that's why they called it

"Radarange"). GaN technology may give us portable microwave ovens as well as theultimate burglar deterrent... and the idea of ultra-efficient microwave central heating that just warms up peoplerather than empty space might even be revived.

* The Air Force likes to claim that millimeter waves are not microwaves -– but as microwaves are generally described as any electromagnetic waves with a wavelength between one millimeter and meter, millimeter waves are microwaves, just as shortwave and longwave are still radio waves.

[Photo: Joint Nonlethal Weapons Directorate]

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