The new team tackled a variety of problems.
By 2003, the dust issue was solved by building a massive clean room and installing the optics in modular dust-free units. Engineers found new ways to produce the thousands of highly polished pieces of laser glass. A faster way was found to grow high-quality crystals that convert the beams to ultraviolet just before they strike the target.
And with four of the planned 192 beams operating, new tests suggested strongly that when the system was fully operating, enough energy would be produced to _ theoretically, at least _ achieve ignition.
Last year, however, a new complication emerged _ not over the laser but the pea-size pellet that contains the hydrogen fuel that will be ignited by the lasers to achieve fusion ignition. Could the pellet be manufactured to the required specifications?
Once its shell was to be made of plastic, but that idea was abandoned. Now the choice is beryllium, a metallic element that can withstand intense heat, is molecularly stable and is a good conductor.
It still is uncertain whether beryllium can be machined to specification, according to technicians who have monitored the program. Last year Congress directed another outside review to report how the development of a beryllium target might affect NIF's timetable.
Like previous challenges in the project's history, the beryllium issue will be resolved, Miller and Moses believe.
While the massive laser may one day have a broad range of scientific uses _ some not even envisioned by today's scientists _ the immediate focus remains assuring the reliability of the nation's nuclear arsenal without actually testing the weapons.
"It gives us confidence that the nuclear stockpile stewardship approach will work," Miller says.
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On the Net:
National Ignition Facility:
http://www.llnl.gov/nif
Natural Resources Defense Council:
http://www.nrdc.org/nuclear/nif/nifinx.asp