LLNL is home to the National Ignition Facility (NIF), the world’s largest and most energetic laser. This international scientific resource is designed to study the physics of matter at extreme densities, pressures, and temperatures. NIF uses 192 laser beams to compress fusion targets the size of an eraser to conditions required for thermonuclear ignition and burn. Since completion of construction in March 2009, the NIF’s unprecedented experimental capabilities have been utilized in support of NIF’s mission areas—national security, fundamental science, and fusion energy. Other experiments have also been completed in support of high-energy-density science, material equation of state, and material strength. In many cases, new records for temperature, pressure, neutron yield, and energy density have been achieved.
Each NIF experimental shot requires the coordination of complex laser equipment, the cryogenic target system, and an array of diagnostics. In the process, 60,000 control points of electronic, optical, and mechanical devices—such as motorized mirrors and lenses, energy and power sensors, video cameras, laser amplifiers, pulse power, and diagnostic instruments—must be monitored and controlled. Peg Folta, former NIF Computing (NIFC) division leader, notes that the precise automation of the controls is one of the most challenging aspects of the system. The precise orchestration of these parts results in the propagation of 192 nanosecond-long bursts of light over a 1-kilometer path length. These 192 beams must arrive at the center of the 10-meter-diameter target chamber within 30 picoseconds of each other, and they must strike within 50 micrometers of their assigned spot on a target measuring less than a centimeter long.
The group of a hundred NIFC computer scientists and technicians, in partnership with teams from Engineering, has developed the Integrated Computer Control System (ICCS) for the NIF that monitor and control the devices comprising the giant laser on the path to ignition. Designed to fire and diagnose laser shots every four hours, the ICCS is based on a scalable software framework that is distributed over some 1500 computers throughout the NIF. The framework provides templates and services at multiple levels of abstraction for the construction of software applications.
A shot automation framework has been developed and deployed to automate a 4–8 hour shot sequence using ICCS, which includes inputting shot goals from a physics model, setting up the laser and diagnostics, automatically aligning laser beams, and verifying status. This sequence consists of a set of preparatory verification shots, leading to amplified system shots using a four-minute countdown, triggering during the last two seconds using a high-precision timing system, and followed by post-shot analysis and archiving.
“The NIF control system is arguably the largest in the world, matched only by perhaps CERN,” Peg says. “We’re a passion-driven team with a large, high-quality integrated staff. We work in support of NIF’s important missions.”