The Next Frontiers of Advanced Lasers Research

WHEN the National Ignition Facility comes on-line in 2003, it will represent the conclusion of one process and the beginning of others. It will be the culmination of more than a decade of research and development to achieve laser ignition-the implosion in a laboratory environment of a small, hydrogen-isotope-filled target by laser beams of sufficient energy and quality to create, for a micro-instant, inertially confined fusion-a process comparable to that at the center of the sun. Simultaneously, it will represent the beginning of other quests, among them to fulfill the ultimate civilian goal of NIF-taking lasers beyond NIF to enable them to create inertial fusion energy, a low-cost, inexhaustible supply of electric power through repeated, sustained laser ignition and fusion energy gain.
Lawrence Livermore National Laboratory recognized and embraced the challenge of taking lasers beyond NIF more than a decade ago, even before NIF was specifically defined. The Laboratory made the early commitment to identify and develop the concepts and technologies that would propel laser applications beyond NIF because we know that the design, development, and construction of each major new experimental program facility take at least 10 years or more. Therefore, positioning large-scale programs to be able to explore the frontiers of new knowledge calls for the earliest possible anticipation of program facility needs and the timely development of the necessary enabling technologies.
In the case of NIF, these research management principles have meant that as the Laboratory solved the scientific problems and developed the technology to make NIF a reality, we almost concurrently had to do the science and provide the technology to take lasers beyond NIF.
Two articles in this issue of Science & Technology Review report on developments that not only will help inertial fusion achieve its immediate goal-ignition-but may provide the enabling technology to make lasers the means of providing inertial fusion energy.
The feature article, "Taking Lasers beyond the National Ignition Facility," beginning on p. 4, makes the compelling point that the flashlamp-pumped neodymium-doped glass (Nd:glass) lasers that NIF will use to create fusion ignition represent several decades of development and scaling. Flashlamp-pumped solid-state lasers have been developed worldwide as the workhorse laser driver of choice for single-shot inertial confinement fusion and high-energy-density research facilities at Livermore and elsewhere. Yet, it was generally believed that solid-state lasers as a class lacked other qualities necessary to effectively drive an inertial fusion energy reactor-namely, the capability to generate fusion-like, megajoule pulse energies simultaneously with output beams characterized by high quality, high pulse-repetition rate (about 10 hertz), and high efficiency (greater than 10%). The article goes on to discuss the conceptual and technological innovations that overcame this long-held perception. It focuses on the part the Laboratory played in developing (concurrently with NIF) the enabling laser technology advances that make diode-pumped, gas-cooled solid-state lasers a candidate for taking lasers beyond NIF to the production of unlimited electrical power based on inertial fusion energy.
In a similar vein, the article on metallic hydrogen (p. 12) reports on a recent Laboratory achievement with promising, significant implications for improving the laser targets that will be used in NIF, broadening their performance range and making them capable of higher performance. The revised information about the equation of state of hydrogen revealed by the Laboratory's hydrogen metallization studies will contribute to the refinement of the hydrogen-isotope-filled targets to be used in the lasers that will make inertial fusion energy a reality.
Different as these two articles are, they have a similar subtext: The achievements they discuss illustrate the emphasis of Laboratory and the Laser Programs on forward-looking research management that plans well ahead for the future implications and applications of the scientific research and development done at Livermore. This research management philosophy is also what makes Lawrence Livermore a continuing key contributor to the global advancement of science and its most important applications.

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