page_title: National Ignition Facility
section_title: Constructing NIF
hierarchical_section_title: National Ignition Facility / History / Constructing NIF
caption_attribution_description: English: The Beamlet laser, a scientific prototype of one of the NIF’s 192 beamlines, that has been operating at LLNL since 1994.
context_page_description: The National Ignition Facility, is a large laser-based inertial confinement fusion research device, located at the Lawrence Livermore National Laboratory in Livermore, California. NIF uses lasers to heat and compress a small amount of hydrogen fuel with the goal of inducing nuclear fusion reactions. NIF's mission is to achieve fusion ignition with high energy gain, and to support nuclear weapon maintenance and design by studying the behavior of matter under the conditions found within nuclear weapons. NIF is the largest and most energetic ICF device built to date, and the largest laser in the world.
  The basic concept of all ICF devices is to rapidly collapse a small amount of fuel so the pressure and temperature reach fusion-relevant conditions. NIF does this by heating the outer layer of a small plastic sphere with the world's most powerful laser. The energy from the laser is so intense that it causes the plastic to explode, squeezing down on the fuel inside. The speed of this process is enormous, with the fuel reaching a peak around 350 km/s, raising the density from about that of water to about 100 times that of lead.
context_section_description: Work on the NIF started with a single beamline demonstrator, Beamlet. Beamlet operated between 1994 and 1997 and was entirely successful. It was then sent to Sandia National Laboratories as a light source in their Z machine. A full-sized demonstrator then followed, in AMPLAB, which started operations in 1997. The official groundbreaking on the main NIF site was on May 29, 1997.
  At the time, the DOE was estimating that the NIF would cost approximately $1.1 billion and another $1 billion for related research, and would be complete as early as 2002. Later in 1997 the DOE approved an additional $100 million in funding and pushed the operational date back to 2004. As late as 1998 LLNL's public documents stated the overall price was $1.2 billion, with the first eight lasers coming online in 2001 and full completion in 2003.
  The physical scale of the facility alone made the construction project challenging. By the time the "conventional facility" (the shell for the laser) was complete in 2001, more than 210,000 cubic yards of soil had been excavated, more than 73,000 cubic yards of concrete had been poured, 7,600 tons of reinforcing steel rebar had been placed, and more than 5,000 tons of structural steel had been erected. In addition to its sheer size, building NIF presented a number of unique challenges. To isolate the laser system from vibration, the foundation of each laser bay was made independent of the rest of the structure. Three-foot-thick, 420-foot-long and 80-foot-wide slabs, each containing 3,800 cubic yards of concrete, required continuous concrete pours to achieve their specifications.
  There were also unexpected challenges to cope with: In November, 1997, an El Niño weather front dumped two inches of rain in two hours, flooding the NIF site with 200,000 gallons of water just three days before the scheduled concrete foundation pour. The earth was so soaked that the framing for the retaining wall sank six inches, forcing the crew to disassemble and reassemble it in order to pour the concrete. Construction was halted in December, 1997, when 16,000-year-old mammoth bones were discovered on the construction site. Paleontologists were called in to remove and preserve the bones, and construction restarted within four days.
  A variety of research and development, technology and engineering challenges also had to be overcome, such as working with the optics industry to create a precision large optics fabrication capability to supply the laser glass for NIF's 7,500 meter-sized optics. State-of-the-art optics measurement, coating and finishing techniques were needed to withstand NIF's high-energy lasers, as were methods for amplifying the laser beams to the needed energy levels. Continuous-pour glass, rapid-growth crystals, innovative optical switches, and deformable mirrors were among the technology innovations developed for NIF.
  Sandia, with extensive experience in pulsed power delivery, designed the capacitor banks used to feed the flashlamps, completing the first unit in October 1998. To everyone's surprise, the Pulsed Power Conditioning Modules (PCMs) suffered capacitor failures that led to explosions. This required a redesign of the module to contain the debris, but since the concrete structure of the buildings holding them had already been poured, this left the new modules so tightly packed that there was no way to do maintenance in-place. Yet another redesign followed, this time allowing the modules to be removed from the bays for servicing. Continuing problems of this sort further delayed the operational start of the project, and in September 1999, an updated DOE report stated that NIF would require up to $350 million more and completion would be pushed back to 2006.
caption: The Beamlet laser tested the design and techniques that would be used on NIF.
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