Gunships, unmanned air vehicles, the Joint Strike Fighter and an upgraded B-2 could all be armed with lasers

The US Air Force Research Laboratory (AFRL) plans tests of a solid-state laser that could lead to gunships, unmanned air vehicles and even the Joint Strike Fighter being armed with directed-energy weapons. The Joint High-Power Solid-State Laser programme will bench-test a 25kW electrically driven laser within two years.

Raytheon and TRW are among competitors for the laser demonstration contract, with award expected by year-end. The programme calls for a laboratory demonstration within two years, followed by delivery of a prototype laser to AFRL for further testing. TRW is proposing a follow-on flight demonstration of a pod-mounted laser.

Increases in the power output of diode-pumped lasers are bringing weapon applications within reach. While a 100kW weapon will be needed for tactical applications, the initial 25kW laser would be suitable for short-range self-defence or non-lethal use at longer ranges. "25kW is a useful number," says Raymond Saunders, head of TRW's office at AFRL's Phillips Laboratory.

The USAF is developing the megawatt-class Boeing AL-1 Airborne Laser (ABL), designed to shoot down ballistic missiles at long range. TRW is producing the truck-sized chemical oxygen iodine laser (COIL) modules for the ABL. Under the Advanced Tactical Laser (ATL) technology demonstration, Boeing is developing a scaled-down COIL producing tens of kilowatts of power and suitable for installation in a Lockheed Martin AC-130 gunship or Bell Boeing V-22 tiltrotor.

Although they produce less energy than coils, solid-state lasers can be electrically powered and avoid the use of toxic chemicals.

TRW's design uses a chain of Nd:YAG diode-pumped "slab" lasers, which amplify the beam to produce the 25kW output.

TRW's proposed flight demonstrator mounts two laser paths either side of a rigid bench inside a pod. The fuel tank-sized pod is self-contained, with power provided by banks of rechargeable batteries and cooling of the diode-pumped lasers provided by a phase-change material that absorbs the heat by melting. Battery power would provide sufficient "shots" for a typical mission, Saunders says. "It would not be long range, and would probably not be lethal," he says.

Potential applications of solid-state laser weapons include a future Northrop Grumman B-2 upgrade and the Boeing A-45 unmanned combat air vehicle. In the AC-130 gunship and Lockheed Martin F-35, power would be provided by the aircraft, Saunders says.

Source: Flight International