Defense Technology International - April 2008 - (Page 33) U.S. ARMY A non-chemical, 100-kw. laser could enable a mobile system for defense against rockets, or as a low-collateral-damage defense against UAVs. Grumman claimed a milestone in December 2007, a full-power test on the first Phase 3 module. This represents the design to be used in the first eightlaser stack. The initial two-module test will follow soon, with an eight-module shot due later this year. The laser modules are stacked like a filing cabinet, in two columns of four. A key to making JHPSSL work is good beam quality—i.e., a flat laser wavefront—in each module, so they form a high-quality beam when ganged together. Beam quality exceeded the specified requirement in the December test, and the laser also ran continuously for 300 sec.—50% better than the target. “Outside Northrop Grumman, I’m not surprised to hear people talk about the challenges of getting good beam quality,” says Dan Wildt, Northrop Grumman’s vice president of directed-energy systems. A 100-kw.-class JHPSSL stack fits in a 1-meter cube, Wildt says, and with the expected 0.15 e ciency factor, needs 700800 kw. of input power. The configuration of an operational system will vary by platform, he suggests. “On an all-electric ship, you’d just hook it up to power and cooling. On a smaller platform, you might not need long run times. You could use batteries and a phase-change cooling material, recharge the batteries and refreeze the coolant between missions.” The JHPSSL weapon might seem to be large for a short-range—“handfuls of kilometers”—weapon that is useful against smaller targets, but Wildt notes it has unique advantages. The cost per shot is extremely low at less than $1 per target, and the elimination of complex guidance simplifies operator training. In a counter-rocket, artillery and mortar (C-RAM) mission, particularly one that involves protecting a base in a populated area, the laser’s advantage is it kills the target by igniting the explosive fill, minimizing damage on the ground. Wildt argues that the laser could benefit ships. It is synergistic with kinetic weapons like guns and missiles. If the target weaves, as the Mach 2.8 rocketpowered kill vehicle of the 3M54 Klub missile is designed to, it exposes its side to the laser and is under g-loading, and more likely to break up when hit. “And if it doesn’t maneuver it gives the kinetic weapons an easier shot,” Wildt adds. For defense against small surface craft, the AviationWeek.com/dti laser’s accuracy and adjustable lethality are an advantage; the laser can immobilize the engine or puncture the hull. Northrop Grumman is one of several companies involved in the next step beyond JHPSSL, the High-Energy Laser Technology Demonstration. Under contracts awarded in the summer of 2007, Northrop Grumman and Boeing are developing beam-control systems—turret-mounted optical chains—compatible with a pre-production JHPSSL. The goal is to test a vehicle-mounted laser C-RAM system in 2013, capable of performing a military mission that would have required a chemical laser. Northrop Grumman is advocating similar demonstration programs for airborne and shipboard applications. “We’d like to work toward full-up prototypes, testing and verifying commercial offthe-shelf batteries and building cooling systems,” Wildt says. The laser team is “very much” working with Northrop Grumman’s NextGeneration Bomber team, as well. I ALMOST READY TO GO RAYTHEON CONCEPT Raytheon’s Vigilant Eagle is Vigilant Eagle a weapon seeking an applicaschematic. tion. The HPM system can knock down man-portable air defense system (Manpads) missiles. It has completed a Dept. of Homeland Security test of its sensor system (from Rafael) and command-andcontrol system (Kongsberg). Raytheon wants to test the DE weapon detecting and negating a pop-up threat and is designing a transportable version geared toward special events. One concern vironment rule out kinetic weapons is that nobody will adopt Vigilant or a man-in-the-loop solution. Eagle until an aircraft is shot down. Booen says DE weapons won’t DE is ideal to counter a Manpads succeed by competing with kinetic airport threat, says Mike Booen, Ray- weapons. “The fundamental antheon’s vice president for missile de- swer is to find a scenario that refense and directed-energy weapons. quires the speed of light to solve a Short reaction time and crowded en- problem.” I HPM jammer drops a missile in test. RAYTHEON APRIL 2008 DEFENSE TECHNOLOGY INTERNATIONAL 33 http://AviationWeek.com/dti
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