Laser Weapons

Liquid Laser program continuing. [Link]

The Pentagon’s mad science arm is moving ahead with a project to build a laser weapon “compact enough to be carried on board a tactical aircraft - say a B-1B bomber or an AC-130 gunship,” Aviation Weekreports.

Darpa is getting ready to hand out 24-month research contracts to defense contractors Textron or General Atomics for the next phase of its High Energy Liquid Laser Area Defense System (HELLADS) program. In the works since 2003, the program is now looking to “build and ground-test” a 150 kilowatt laser weighing about 750 kilograms early in 2012. If it works, the result would not only be a power-to-weight ratio ten times better than existing laser systems. It could mean the next step in giving the U.S. a fleet of laser-blasting aircraft.

Lasers all work in pretty much the same way: Excite certain kinds of atoms, and light particles — photons — radiate out. Reflect that light back into the excited atoms, and more photons appear. But performance varies wildly, depending on the kind of “gain medium” — the type of atoms — you use to generate the beam. Textron is looking to use thin crystal slabs, if it gets the HELLADS contract. But those kind of lasers can rapidly overheat and suffer damage (a laser with a 50% efficiency generates the same amount of waste heat as the energy in the beam). A “liquid laser” like General Atomics approach to HELLADS should be less vulnerable to this, since the liquid can be cooled by circulation.

Drone Zapped by Laser Death Beam [Link]

In a recent series of tests at the Naval Air Warfare Center, China Lake, Calif., a trailer-mounted laser was able to knock five unmanned aircraft out of the sky.

The demo, sponsored by the Air Force Research Laboratory, was a test of the Mobile Active Targeting Resource for Integrated eXperiments (MATRIX), an experimental system developed by Boeing Directed Energy Systems. According to a company news release, the test showed the ability to take down a hostile unmanned aircraft with a “relatively low laser power” weapon. According to AFRL, MATRIX uses a two and a half kilowatt-class high energy laser.

While ballistic missile defense may get all of the press, some homeland-security experts worry about a more low-tech threat: drone technology. Bill Baker, chief scientist of the Air Force Research Laboratory’s Directed Energy Directorate, said in a statement that the shootdowns “validate the use of directed energy to negate potential hostile threats against the homeland.”

It’s not clear, exactly, how the lasers shot down the drones: Whether they disrupted the aircraft controls, or burned a big hole in them. (An AFRL news release said the drones were “acquired, tracked and negated at significant ranges” but offered few additional details.)

As part of the counter-drone tests, Boeing also shot down an unmanned aircraft with its Laser Avenger system, a Humvee-mounted directed-energy air defense system the company is developing. They also test-fired a lightweight 25mm machine gun integrated on the Laser Avenger platform (the machine gun fired at a static target board, not a drone). The idea behind this is to use good ol’ kinetic energy — i.e., a stream of hot lead — as a backup if the directed energy system fails to down the target.