LIVERMORE, CALIFORNIA--Researchers have pulled the plug on a key component of what was long the world's biggest and most powerful laser, the Nova, located here at Lawrence Livermore National Laboratory. The shutdown of the "Two-Beam" target chamber on 12 November marks the beginning of the end of what was a fusion-research workhorse for more than a decade.
The now-defunct Two-Beam, which was completed in 1985, is an extension of two of Nova's 10 arms into a cavernous wing of a four-story building. Two-Beam began as a laboratory for studying the physics of x-ray lasers--then championed by Livermore as the missile-killers in the ill-fated "Star Wars" antiballistic missile shield. But it was also the scene of major civilian advances: In 1992, the laser's measurements of iron opacity helped astronomers correct mathematical models of Cepheid variable stars. Two-Beam also made the world's first x-ray laser micrograph, which showed DNA strands packed into the head of a rat sperm. Its swan song was an experiment probing the behavior of hydrogen under extreme heat and pressure.
Two-Beam's demise is the first step toward dismantling Nova altogether, says Joseph Kilkenny, who runs the lab's laser fusion programs. The rest of the laser will become history in less than 2 years. "It will be a sad day for me when we turn it off," he says. But happier days await laser researchers: Nova's successor, the $1.2 billion National Ignition Facility, is under construction at Livermore, with an expected startup of the first module--packing twice Nova's power--in 2001.