1974 Lasers and ICF

Lasers Join the Quest to gain a better understanding of laser plasma physics and thermonuclear physics and to demonstrate for Fusion Energy laser-induced compression and thermonuclear burn of deuterium–tritium. It was also used to improve the LASNEX computer code developed for laser With the goal of achieving energy gain fusion predictions. Janus was just the In 1975, the one-beam Cyclops laser through inertial confinement fusion beginning of the development, in quick began operation, performing important (ICF) as its mission, the Laser Program succession, of a series of lasers, each target experiments and testing optical constructed its first laser for ICF building on the knowledge gained from designs for future lasers. The next year, experiments in 1974. Named Janus, the last, leading to the National Ignition the two-beam Argus was built. Use of the two-beam laser was built with about Facility (NIF), currently performing Argus increased knowledge about laser– 100 pounds of laser glass. experiments. The pace of laser target interactions and laser propagation The first Livermore laser for construction matched the growth limits, and it helped the ICF program prepared the Laboratory to take the With the 20-beam ICF research, Janus, had Under the leadership of John Emmett, in ICF diagnostics capabilities, develop technologies needed for the next major step, construction of the Shiva laser in 1977, the two beams and produced who headed the Laser Program from computer simulation tools, and next generation of laser fusion systems. 192-beam NIF (see Year 1997), where Laboratory established 10 joules of energy. 1972 to 1988, researchers used Janus theoretical understanding. scientists are striving to achieve fusion its preeminence in laser The $25-million 20-beam Shiva became ignition and energy gain. science and technology. the world’s most powerful laser in 1977. Almost the size of a football field, it delivered 10.2 kilojoules of energy in less than a billionth of a second in its first full-power firing. Two years later, Inertial Confinement Fusion Shiva compressed fusion fuel to a density 50 to 100 times greater than In a fusion reaction, two nuclei—deuterium and tritium—collide and fuse its liquid density. Shiva provided more together, forming a heavier atom and releasing about a million times power, better control over conditions, more energy than in a chemical reaction such as fossil fuel burning. higher temperatures, and greater fuel The nuclei must travel toward each other fast enough to overcome compression than any previous laser. electrostatic forces. Thus, the fuel’s temperature must be over 10 million kelvin, and the fuel must be compressed to a density 20 times greater The Novette laser came on line in 1983 than that of lead. Laser beam as a test bed for the Nova laser design light heats the surface of the and an interim target experiment facility. fuel pellet and rapidly vaporizes It was used to demonstrate the efficient its outer shell, which implodes coupling of higher-harmonic laser light the inner part of the fuel pellet to fusion targets and to create the first and reduces it in size by a factor soft-x-ray laser. The Nova laser (see of 30 or more—equivalent to Year 1984), 10 times more powerful than compressing a basketball to the Shiva, was built the following year. size of a pea.

Altogether, six large fusion laser A typical hohlraum for the Nova systems were engineered and built laser is shown next to a human hair. in 10 years. The next decade of ICF Hohlraums for the National Ignition research was devoted to studying and Facility have linear dimensions about demonstrating the physics required for five times greater than those for Nova. fusion ignition and gain (fusion output greater than energy input). The work

LAWRENCE LIVERMORE 52 NATIONAL LABORATORY LAWRENCE LIVERMORE 53 NATIONAL LABORATORY