LIVERMORE, CA--On the way to its official dedication on May 29, 2009, the National Ignition Facility (NIF; lasers.llnl.gov) at Lawrence Livermore National Laboratory endured many funding cuts and criticisms; after all, a multi-billion dollar project always raises suspicions about management and viability of the technology. Nonetheless, NIF is now producing real data: Just recently, symmetrical implosion of the small hohlraum capsule that will eventually hold nuclear material was achieved. The symmetry aspect is important and necessary to optimize the energy on the capsule's surface so that fusion burn can be initiated. After all, the ultimate goal of NIF is to get 10 to 100 times more energy out than was put into the system. While these experimental results are exciting, nothing comes close to actually visiting the NIF facility and understanding how the true power of science is being applied towards an energy rich future.
During Photonics West 2010, a lucky two-dozen or so individuals, including myself and Tom Hausken from Strategies Unlimited, attended the Thursday afternoon NIF tour on January 28. Ultimately, the 192-beam NIF will generate 1.8 MJ or 500 TW of ultraviolet laser energy. It sounds like a lot of power, but the message really comes across when you stare out into the beam line in a building the size of three football fields and look both down and up at the dizzying 5 stories above and 5 stories below the see-through mesh near the target chamber in this 10-story building. It's phenomenal that such a large bunch of hardware will deliver 192 well-focused beams onto a target the size of a pencil eraser containing a bb-sized capsule of nuclear material. What is even more impressive is the fact that one gallon of seawater contains enough deuterium to produce the equivalent energy from 300 gallons of gasoline. And more incredible still, 60,000 control points for managing electronics, high-voltage signals, optics (26,000 small optics and 7500 large meter-scale optics), and mechanical devices, must come together and insure that those 192 laser beams (which travel about 1500 m) have optical path lengths equal to within 9 mm so that the pulses arrive within 30 trillionths of a second of each other at the target chamber's center. Whew!
Rose-colored glass
One of the more striking parts of the tour was actually seeing the special phosphate glass doped with neodymium that is used to amplify the initial laser pulses. These slabs of rose-colored glass are about three feet long and 3000 or so are needed to complete the amplification process. On the tour, the guide explained how NIF scientists worked to develop a continuous-flow fabrication process for this special glass.
Take the tour
But don't take my word for it; words really don't do the NIF justice. The public is welcome to tour the NIF facility, and a special "technical" tour is available by request for those individuals that are interested in all the nitty gritty details of how the NIF works. You can schedule a tour by calling the Community and External Relations Office at LLNL at (925) 422-4599. For technical tours, call Carrie Martin directly at (925) 424-4175 or send an email to [email protected]. If you do schedule a tour, prepare to be impressed!
