LASER WEAPONS

Technicians at TRW (Redondo Beach, CA) are preparing a high-energy "baseline demonstration" chemical laser for a series of tests to measure output power and chemical efficiency. Based on tests completed in early August, TRW says it has demonstrated the laser performance needed to build a megawatt-class laser required for the US Air Force Airborne Laser (ABL) theater ballistic-missile defense system. The laser would be placed aboard a modified 747 aircraft and destroy missiles during powered boos

LASER WEAPONS

TRW laser module meets missile defense needs

Rick DeMeis

Technicians at TRW (Redondo Beach, CA) are preparing a high-energy "baseline demonstration" chemical laser for a series of tests to measure output power and chemical efficiency. Based on tests completed in early August, TRW says it has demonstrated the laser performance needed to build a megawatt-class laser required for the US Air Force Airborne Laser (ABL) theater ballistic-missile defense system. The laser would be placed aboard a modified 747 aircraft and destroy missiles during powered boost when the missiles were still above their launch site, "hundreds of kilometers" from the aircraft, when they are the slowest and most vulnerable. The company is supplying the laser as part of a contractor team led by Boeing (Seattle, WA), which is providing systems integration for the effort. The team also includes Lockheed Martin (Palo Alto, CA), which is responsible for optics and beam-steering technology.

The ABL is to be based on chemical oxygen iodine laser (COIL) technology. The tests measured laser output power "in hundreds of kilowatts" and chemical efficiency "in tens of percent." The device shown is a full-power prototype of a lighter laser module building block the team is proposing to cluster together to form the full-scale ABL laser.

In a COIL, hydrogen is reacted with chlorine gas, producing excited oxygen molecules. These in turn are mixed with iodine, resulting in energized iodine atoms. The iodine atoms lase and give off photons when they transition to a lower energy state. An optical resonator in the COIL lasing cavity is used to amplify the photon stream that forms the resulting beam.

Paul Shennum, ABL program manager for Boeing, says the efficiency shown in the tests will allow for a smaller and lighter COIL laser system and reduced chemical requirements. "The ABL 747 aircraft will be able to fly higher with increased effective laser range or remain on station longer," says Shennum.

The Boeing team is in competition for the ABL system with a grou¥headed by Rockwell International that includes Hughes (both in Los Angeles, CA) and E-Systems, a Raytheon company (Lexington, MA). One of the two teams will be selected in November 1996 to conduct a $1.1 billion program definition and risk reduction phase, culminating in a demonstrator for flight tests in fiscal year 2000 that can serve as the basis of operational aircraft.

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