Livermore, California 94551 BoxP.O. 808,L-664 Lawrence LivermoreNationalLaboratory Science & Technology Review December 1996

Lawrence Livermore National Laboratory

CrossingCrossing thethe PetawattPetawatt ThresholdThreshold

Also in this issue: emtN.154 Permit No. Livermore, CA Nonprofit Org. .S Postage S. U. PAID • Stockpile Surveillance • Earth Core Studies Printed on recycled paper. • 3-D Computer Motion Modeling About the Cover December 1996 S&TR Staff December 1996

Lawrence Livermore Adjusting a diagnostic lens in Lawrence National Lawrence Livermore’s new ultrashort-pulse laser, called Laboratory SCIENTIFIC EDITOR Ravi Upadhye Livermore the Petawatt, is laser physicist Deanna National Pennington. World-record peak power of 1.25 Crossing the Laboratory petawatts (1.25 quadrillion watts) was reached Petawatt Threshold PUBLICATION EDITOR May 23, 1996. In this issue beginning on p. 4, Sue Stull we discuss the challenges and development of this extraordinary laser. WRITERS Bart Hacker, Arnie Heller, Dale Sprouse, Katie Walter, and Gloria Wilt 2 The Laboratory in the News

ART DIRECTOR George Kitrinos 3 Commentary by E. Michael Campbell Opportunities for Science from the Petawatt Laser DESIGNERS Also in this issue: • Stockpile Surveillance Paul Harding, George Kitrinos, and • Earth Core Studies Features • 3-D Computer Motion Ray Marazzi Modeling 4 Crossing the Petawatt Threshold Cover photo: Bryan L. Quintard GRAPHIC ARTIST The new Petawatt laser may make it possible to achieve fusion using much Treva Carey less energy than currently envisioned.

INTERNET DESIGNER 12 High Explosives in Stockpile Surveillance Indicate Constancy Kathryn Tinsley A well-established portion of the Stockpile Evaluation Program performs extensive tests on the high-explosive components and materials in COMPOSITOR Louisa Cardoza Livermore-designed nuclear weapons.

What Do You Think? PROOFREADERS Research Highlights Al Miguel and Jill Sprinkle 18 Visualizing Body Motion We want to know what you think of our publication. Please use the enclosed survey form 21 Studying the Earth’s Formation: The Multi-Anvil Press at Work to give us your feedback. S&TR is a Director’s Office publication, produced by the Technical Information 24 Patents and Awards Department, under the direction of the Office of Policy, Planning, and Special Studies. 26 Abstracts Electronic Access 27 1996 Index S&TR is available on the Internet at http://www.llnl.gov/str. As references become available on the Internet, they will be interactively Printed in the United States of America linked to the footnote references at the end of each article. If you desire more detailed information Available from National Technical Information Service about an article, click on any reference that is in U.S. Department of Commerce color at the end of the article, and you will connect 5285 Port Royal Road automatically with the reference. Springfield, Virginia 22161

UCRL-52000-96-12 Page 4 Distribution Category UC-700 December 1996 About the Review

Lawrence Livermore National Laboratory is operated by the University of California for the Department of Energy. At Livermore, we focus science and technology on assuring our nation’s security. We also apply that expertise to solve other important national problems in energy, bioscience, and the Page 12 environment. Science & Technology Review is published ten times a year to communicate, to a broad audience, the Laboratory’s scientific and technological accomplishments in fulfilling its primary missions. ¥ ¥ The publication’s goal is to help readers understand these accomplishments and appreciate their value to the individual citizen, the nation, and the world. Prepared by LLNL under contract Please address any correspondence (including name and address changes) to S&TR, Mail Stop L-664, Page 18 No. W-7405-Eng-48 Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, or telephone (510) 422-8961. Our electronic mail address is [email protected]. 2 The Laboratory in the News Commentary by E. Michael Campbell 3

Director looks at Lab’s technical challenges “The deterrence mission remains the underpinning of our Opportunities for Science Describing himself as very optimistic about Lawrence national security,” Reis noted, and the ASCI supercomputer Livermore’s progress and future, Director Bruce Tarter says will be a “central tool” in efforts to keep the nation’s that in the coming year, the Laboratory will “have to deliver stockpiled nuclear weapons safe and reliable. from the Petawatt Laser on major products” in addition to “first rate R&D” in the areas Contact: Jeff Garberson, LLNL Media Relations, (510) 422-4599 of national security, energy, and biotechnology. ([email protected]). With the country committed to no nuclear testing under the Comprehensive Test Ban Treaty, Lawrence Livermore must AVLIS team puts enrichment technology through “focus on providing Congress and the President with high its paces confidence in the stockpile,” the Director said. “This means an The Laboratory’s Atomic Vapor Laser Isotope Separation URING the past 25 years, Lawrence Livermore has These advances in laser science and optical component enhanced effort on surveillance and life extension of the (AVLIS) team has a new goal: extend operating hours for D become a world-renowned research center for designing, fabrication have enabled revolutionary new concepts in laser current stockpile and rapid progress on major initiatives.” He the Livermore-developed uranium enrichment technology, building, and utilizing high-peak-power and high-energy science and machining as well as information display stressed that the National Ignition Facility (NIF) must remain demonstrating the reliability required of a fully functioning lasers. Starting with the 100-million-watt, two-beam Janus production technologies. on schedule and within costs and that the Accelerated enrichment plant by the end of the calendar year. Achieving laser in 1974, we designed and built a series of laser systems, What’s more, the enormous energy density of the Strategic Computing Initiative (ASCI) must be a “fast-track that goal means around-the-clock, seven-day-a-week each providing five to ten times more irradiance (power per Petawatt will push back the frontiers of knowledge about program.” NIF and ASCI are two key components of the effort operation of the key AVLIS Demonstration Facility areas: unit area) than its predecessor. laser–matter interaction and expand our knowledge of matter to ensure the integrity of the nation’s nuclear weapons lasers, separators, and control devices. Our series of increasingly more capable facilities now under extreme conditions. For the first time in a laboratory stockpile without nuclear testing. AVLIS personnel have been running ever-lengthening culminates in a revolutionary one-aperture laser, the Petawatt, setting, we will be exploring relativistic plasma physics and Tarter said the Laboratory’s challenge in energy is proving, endurance tests at Livermore for the U.S. Enrichment Corp. with output power exceeding a quadrillion watts. Using the new sources of coherent and incoherent radiation at high with the U.S. Enrichment Corp. (USEC), that “laser isotope (USEC). These design verification runs are aimed at technique of chirped-pulse amplification, which enables us to photon energy. separation can work in the commercial environment.” USEC bringing the technology to the point where USEC can use it produce very short (less than a trillionth of a second) energetic Finally, the Petawatt will allow us to test a new pathway to has designated the Lab’s isotope separation technology as the for commercial production of enriched uranium. pulses on one arm of the ten-arm Nova laser, the Petawatt is laser fusion, called “fast ignition,” that was developed at way to make reactor fuel in the 21st century (see AVLIS news USEC, a U.S. government corporation in the process of able to exceed the total power of Nova by a factor of 10. Lawrence Livermore early in this decade. As described in the item next column). privatizing, produces and markets uranium enrichment Even more impressive than its output power is the article, the fast-ignition concept cleverly sidesteps the most In biotechnology, Tarter said, stronger production services worldwide. It selected Lawrence Livermore- Petawatt’s extraordinary brightness. Coupled with innovative difficult aspects of achieving fusion ignition with capability will be needed to sequence the human genome. developed AVLIS enrichment technology as the focusing schemes, this brightness will enable the Petawatt to conventional inertial confinement fusion design. Explained the Director: “For the last half dozen years, we have “technology of choice” to ensure that the U.S. maintains its be focused to irradiances that produce an electric field The enormous opportunities created by the Petawatt will been mapping with markers to lay out the structure of the lead in the world uranium enrichment market. exceeding by a factor of 100 the force that binds an electron keep Lawrence Livermore in the forefront of high-power genome; now we have to sequence it, that is, fill in all the In a 200-hour test in September, the AVLIS separator to a proton in the hydrogen atom. laser physics and high-energy-density physics for the details—a much more production-oriented activity that is operated around the clock for 6 days, processing 3 metric “Crossing the Petawatt Threshold,” beginning on p. 4, foreseeable future. driven by national and international competition.” tons of uranium. describes the major technical and scientific advances that Tarter outlined the challenges facing the Laboratory in the Contact: Bruce Warner, Lawrence Livermore AVLIS Program were required to make a petawatt laser a reality at Livermore. ■ E. Michael Campbell is Associate Director, Laser Programs. coming year in an address to employees in early October. Manager, (510) 422-9237 ([email protected]) or Victor Lopiano, Discussing the budget for FY 1997, Tarter said the Lab’s total USEC Director of AVLIS Enrichment and Livermore Operations, costs will be $1,057 million, with $929 million going to (510) 424-2851 ([email protected]). operating costs and the remainder to construction and major capital procurements. Nonproliferation, arms control focus of Lab Contact: Jeff Garberson, LLNL Media Relations, (510) 422-4599 workshop ([email protected]). As a followup to a 1995 workshop in Snezhinsk, Russia, Russian and American scientists met at Livermore in Reis dedicates ASCI–Blue Pacific September to explore the possibility of joint projects in arms Mission, partnership, and technology were the themes as control and nonproliferation technologies. Discussed at the Vic Reis, the DOE’s assistant secretary for Defense Programs, workshop were possible collaborations on technical visited the Laboratory in late October. At Livermore, he approaches to a wide range of international problems. dedicated ACSI–Blue Pacific, the 3-trillion-calculations-per- Principal attendees were from the Russian Ministry of second supercomputer being built as part of the DOE’s Atomic Energy, the All Russian Institute of Experimental Accelerated Strategic Computing Initiative (ASCI). Physics, the All Russian Institute of Technical Physics, and Targeted for demonstration in December 1998, the Los Alamos, Sandia, and Lawrence Livermore National supercomputer is a collaboration between Livermore and IBM Laboratories. Also represented were the U.S. Departments in which, said Reis, “both partners bring unusual talent.” of Energy, Defense, and State and the Russian Ministry of Foreign Affairs. Contact: Paul Herman (510) 423-0945 ([email protected]).

Science & Technology Review December 1996 Science & Technology Review December 1996 4 Petawatt Crossing the Petawatt 5 Petawatt Threshold

An extraordinarily powerful new OR more than three decades, to keep a 100-watt light bulb burning Townes was visiting the Laboratory on mid-1980s of a unique new laser F Lawrence Livermore’s Laser for about 6 seconds. the same day, May 23, as a member of a material—titanium-doped sapphire laser promises to help make fusion Programs have earned a worldwide By crossing the petawatt threshold, panel reviewing the Laser Programs (Ti:sapphire)—offered high gain over a reputation for pushing the limits of laser the laser heralds a new age in laser (see Figure 1). Townes was awarded the broad range of wavelengths. Together power more easily attainable with technology. But few accomplishments research. Lasers that provide a petawatt Nobel Prize in 1964 for co-inventing with a new technology—chirped-pulse have rivaled the one celebrated in the of power or more in a picosecond may the first laser, which generated only a amplification (CPA) to minimize laser “fast ignition.” The laser beam’s early morning hours of May 23, 1996, make it possible to achieve fusion using few thousandths of a watt. materials damage—they offered the by an exhausted but exuberant crew that significantly less energy than presently “When the laser first came along, possibility of creating high-power ultrashort pulses and extremely just used a revolutionary laser that envisioned, through a novel Livermore I never imagined it getting up that subpicosecond pulses directly from a produced more than a quadrillion watts concept called fast ignition. (See high,” Townes told reporters. “When solid-state laser. Lawrence Livermore high intensities will also enable of energy, a world record. Science & Technology Review, we first invented them, I was thinking researchers began work on short-pulse The extraordinarily powerful laser is September 1995, for more information.) about very modest powers. It never lasers in the mid-1980s and completed a researchers to advance their called the Petawatt because the prefix The Petawatt laser will also enable occurred to me it would be in this kind 10-terawatt (TW) laser in 1989. The “peta” refers to a quadrillion, or 1015. researchers to study the fundamental of ballpark.” embodiment of most of the advances understanding of the fundamental The laser reached a peak of 1.25 properties of matter, thereby aiding the Indeed, the Petawatt is only the latest since that time resides in the Petawatt. petawatts of peak power, about 25% Department of Energy’s stockpile of a family of lasers with increasing With its full-aperture beam of nature of energy and matter. more powerful than expected and more stewardship efforts and opening entirely irradiance (power per unit area) that 58 centimeters in diameter (to be than ten times the peak power of new physical regimes to study. began in the 1970s with LLNL’s Argus, installed in early 1997 to replace a Lawrence Livermore’s Nova laser, the Coincidentally, University of Shiva, and then Nova laser systems (see 46-cm beam), the Petawatt will produce world’s largest. The historic shots California at Berkeley professor Charles Figure 2). The introduction in the about 1 kilojoule of energy in less than shattered the existing record for laser power (125 trillion watts) by more than a factor of 10, set by Livermore LLNL 1,250-TW (petawatt) Nd:glass laser (May 1996) researchers using a Petawatt prototype during the summer of 1995. 1,000 Although the shots exceeded by more than 1,200 times the entire electrical generating capacity of the U.S., they LLNL 100-TW Nd:glass laser lasted less than half a picosecond 100 (a trillionth, or 10–12, of a second). In CEA-Limeil P102 that exceedingly fleeting moment, Rutherford Vulcan CPA nearly 10,000 times shorter than the NIF (single beam) LLNL 10-TW Nd:glass laser typical Nova laser shot, only enough 10 energy (about 600 joules) was generated Peak power, terawatts Shiva Nova (single beam) (single beam) 1 Argus T3 University of Rochester

Laser physicist Deanna Pennington Figure 1. With the Petawatt is laser in adjusts a diagnostic lens within the the background, Livermore’s Michael 7478 82 86 90 94 98 02 Petawatt’s compressor chamber. At right Perry (left) shows how far the Year is one of the diffraction gratings, while technology has come to UC Berkeley behind her are a turning mirror and the Professor Charles Townes, who Figure 2. Milestones in laser development: early lasers (yellow), long-pulse technology (green), second compressor grating. co-invented the laser. and chirped-pulse amplification technology (blue).

Science & Technology Review December 1996 Science & Technology Review December 1996 6 Petawatt Petawatt 7

0.5 picosecond. In contrast, one Perry formed a core team of demonstration occurred for solid-state compressed using a pair of diffraction metallic gratings are simpler to this and other spinoff technologies beamline of Nova typically produces physicists, engineers, and technicians lasers in the late 1980s at the University gratings each 74 centimeters in manufacture than the multilayer discussed in the box below.) 10 kilojoules of energy in 1 nanosecond with backgrounds in laser physics, of Rochester. Further developments at diameter. By reversing the process of gratings. Multilayer gratings would be With the grating technology in hand, (billionth of a second), some 1,000 times optics, engineering, materials science, Rochester, Lawrence Livermore, and the stretcher (now the red components required to achieve the multikilojoule the focus of the Petawatt team moved to slower. Nova and the National Ignition and atomic physics. Team members elsewhere along with the introduction of travel a longer length than the blue), pulses necessary to achieve ignition if installation of the petawatt system on Facility (NIF) planned for Livermore knew that success required advances in new laser materials (e.g., Ti:sapphire) the pulse is compressed down to less fast-ignitor capability is added to the the Nova laser. Numerous large-scale are long-pulse lasers (nanoseconds and knowledge of the basic behavior of have revolutionized high-power laser than half a picosecond (nearly its NIF. Interestingly, the multilayer optical and mechanical components longer), specifically designed to optical materials, development of new research. (See Figure 3.) original duration), thereby increasing dielectric grating technology has capable of working at extreme precision produce high-pulse energy. diffraction grating technology, CPA is critical because laser pulses of its peak power nearly 10,000 times to already produced its own spinoff. (See under vacuum had to be designed, substantial improvements in short-pulse extremely high power density more than a petawatt. Such pulses must Petawatt Development laser technology, and advancement of a (gigawatts/centimeter2, or GW/cm2) can be compressed in a vacuum because The Petawatt Advanced Fusion sound theoretical basis for the fast- severely damage optical components the irradiance of the beam leaving the Project was proposed in 1992 as a high- ignitor concept. Finally, they recognized such as amplifiers, lenses, and mirrors. second grating is over 700 GW/cm2, Petawatt Spinoffs risk, potentially high-payoff project to that although an all-Ti:sapphire laser With CPA technology, it became possible far too great to pass through any develop the capability to test the fast- could not provide sufficient power, a to generate very short laser pulses with material (including air) without The technology developed for the Petawatt has provided many unexpected ignitor concept for inertial confinement hybrid system starting with a Ti:sapphire extremely high peak powers by stretching resulting in damage. spinoffs. In particular, Lawrence Livermore’s experimental and theoretical studies of fusion (ICF) and to provide laser and using new, smaller, and more a low-energy laser pulse more than laser-induced damage, carried out in support of the Petawatt laser’s development, have Livermore—and the world—with a efficient neodymium glass amplifiers 10,000 times its duration prior to The Grating Challenge created valuable new technologies. Researchers, led by Brent Stuart, using the petawatt front end made pioneering measurements of the laser damage threshold for a multitude unique capability in high-energy- could provide the necessary pulse energy amplification and then recompressing the One of the most challenging of optical materials (crystal and glass) lasting from 0.1 picosecond to 1 nanosecond. A density physics. Michael Perry, leader and bandwidth to achieve a petawatt. pulse back to near the original duration tasks was the fabrication of pulse fundamental change in the damage mechanism is observed when the pulse length is of Lawrence Livermore’s Short-Pulse Much of the Petawatt’s early effort after amplification. Because passage compression gratings of sufficient size, less than approximately 20 picoseconds. This change in mechanism is accompanied by Lasers, Applications, and Technology was devoted to further developing CPA through the laser optics occurs when the optical quality, and ability to withstand a dramatic change in the morphology of the damage site. Program, won a competitive grant in technology. CPA was first developed to pulse is long, there is no damage. the enormous power of the Petawatt The discovery and explanation of this difference formed the basis of a 1993 from LLNL’s in-house Laboratory increase the power of radar systems and Using this technology, the Petawatt laser pulse. Said Perry, “When the collaborative program with medical researchers on the interaction of short laser pulses Directed Research and Development was discussed for use in lasers in the laser begins with a broad-bandwidth, project began, there wasn’t a facility in with human tissue. Laser ablation of tissue (removal of tissue by its being “blown off”) program to begin building the laser. middle 1970s. The first successful low-power pulse lasting less than the world capable of making the has great promise in a number of therapeutic situations requiring precise material 0.1 picosecond in a temperature- required gratings, so we created one.” removal with minimal disturbance of the surrounding tissue. Potential applications controlled clean room in the basement of The diffraction gratings that are include precision cutting (as in keratonomy), perforation (applicable to middle ear the Nova building. Instead of consisting used in the Petawatt laser are nearly surgery), pressure release for hydroencephaly, and dental drilling. The advantage for Initial short pulse surgery with lasers whose pulses last less than a picosecond is that the duration is far of a single, very specific wavelength 1 meter in diameter, some eight times too short to transfer heat to surrounding tissue. (See the October 1995 S&TR for more (color) produced in conventional lasers, larger and twice as resistant to damage on LLNL efforts to develop short-pulse lasers as safe and painless surgical tools.) The these ultrashort pulses contain a broad as the previous state of the art. ability to cut and drill material with no heat or shock has also found important Short-pulse oscillator Metallic spectrum. Before amplification, the short- Livermore’s successful development of gratings application in LLNL’s role in nuclear weapon stockpile management. pulse beam is sent to the pulse stretcher. diffraction grating technology for the Two R&D 100 Awards were earned as a result of the need to manufacture Here, the pulse is stretched by using a Petawatt led to the selection of gratings diffraction gratings to a size, precision, and resistance to optical damage never before High-energy pulse diffraction grating to spread out the for many uses on the National Ignition attained. The first, earned in 1994, was the development of multilayer dielectric different wavelengths (colors), separating Facility (NIF), a 192-beam laser gratings for use in dispersing light into constituent colors, or wavelengths, for many different applications. These gratings, made of multiple layers of thin dielectric film, Long, low pulse each frequency component. By passing facility planned for Livermore. each color through a different optical Initially, achieving a petawatt of have much higher damage thresholds than metallic gratings and can be custom path length (the red components travel a peak power was expected to require an designed for narrow- or broad-bandwidth use. Besides their use in new generations of extremely high-powered lasers, they may be used in entirely new products in such shorter length than the blue), the pulse is entirely new optical component—a areas as remote sensing and biomedical diagnostic systems. (See the September 1994 Power amplifiers stretched in time by a factor of 30,000 to high-efficiency, multilayer dielectric E&TR for more information.) Furthermore, the grating development laboratory and 3 nanoseconds. The pulse is then grating. That advanced technology was technology will be used for developing the extensive diffractive optics used throughout amplified more than a trillion times developed by the Petawatt team in the final focus assembly of the planned National Ignition Facility. without damaging the laser glass as the 1993 and 1994, an achievement High-energy The technology developed to produce the multilayer and metallic gratings with Second pair of pulse travels through a series of amplifier recognized in 1994 with an R&D 100 extremely small features (down to 0.1 micrometer) may also give a dramatic boost to metallic gratings ultrashort pulse modules, including a portion of one arm Award. However, the dielectric American producers of flat-panel displays. The LLNL process to laser interference of the Nova laser for the final amplifier gratings were not used in the current lithography enables the production of large-area field-emission displays (FEDs). This stage. experiments because new metallic display can be thinner, brighter, larger, and lighter and can consume less power than Figure 3. The concept of how chirped-pulse amplification and other new technologies After amplification, the beam is gratings developed by the team have traditional active matrix liquid crystal displays. The new technology earned its inventors an R&D 100 Award in 1996 (see the October 1996 S&TR). enable the production of the petawatt (quadrillion-watt) pulses. then sent to the vacuum chamber 3 ¥ 11 proven satisfactory for petawatt pulses meters long, where the pulse is at 0.5-picosecond durations. These

Science & Technology Review December 1996 Science & Technology Review December 1996 8 Petawatt Petawatt 9

fabricated, and installed. Significant produce a short pulse length. Following underground master oscillator room can installed between the Petawatt’s Focusing Petawatt Pulses accommodate a wide variety of modifications to the ten-beam target bay the March 1995 shot series, the new take one of four courses. First, it can be compression chamber and Nova’s ten- A significant problem with petawatt experimental conditions and targets. To were performed over many weekends, injection beamline between the Petawatt’s injected into the Nova chain to the beam chamber. It will permit the pulses is how to focus them. date, over 90% reflectivity has been when the Nova laser is usually not used master oscillator room and the Nova Petawatt’s compressor chamber and Petawatt laser to be used independently Conventional approaches such as demonstrated in small-scale for target experiments. A new beamline preamplifier was activated, along with the used along with nine of Nova’s ten of Nova. lenses or mirrors with debris shields experiments conducted with the was installed to route the beam from the compression chamber vacuum system and beams as a large-scale hybrid system to The decision to develop a target cannot be used because these both Petawatt’s front end. Petawatt’s master oscillator room to a full suite of optical diagnostics. The test the fast-ignitor concept and chamber exclusively devoted to petawatt involve transmissive optics that would the disk amplifier section of Nova’s final test series performed in May 1996 investigate new concepts in laser–matter laser use, while retaining the ability to be damaged by the extreme power Possible Key to Fast beamline number 6 for final produced the record-shattering result, but interactions and plasma physics. Second, perform experiments in Nova’s ten-beam density of the petawatt pulse (over Ignition amplification. A particularly challenging not without exceptionally hard work. “We the beam can be shunted to a small room target chamber, was prompted by the 700 GW/cm2). The Petawatt provides researchers task was installation of the enormous had to work 16-hour days, 7 days a week next door to the master oscillator room, high level of interest expressed by A radical concept proposed by Perry with their first tools to explore the fast- compression chamber in the target bay for more than a month to make sure where it is used for researching issues researchers at LLNL and other centers. and Associate-Director-at-Large John ignitor fusion concept, conceived by without disrupting the normal operation everything was ready for the related to the use of lasers in medicine Building a petawatt target chamber Nuckolls was the use of a so-called Livermore’s Max Tabak and others in of the Nova system. demonstration shots. It was a true team and material processing, development of makes good sense, says Perry, “because “plasma mirror.” The intense petawatt 1992. Focusing a high-power laser With everything in place, three series effort between the Nova engineers, plasma mirrors, and harmonic it will allow us to work the bugs out of beam strikes the front surface of a piece pulse gives rise to an extremely high of experimental shots were performed. In operations crew, and the Petawatt project conversion to a shorter wavelength for the Petawatt’s focusing system and of polished glass, creating a very-short- density of energy, or light pressure. the first series, performed in December team,” recalls Perry, who furnished non- Nova x-ray diagnostics development. enable simple, single-beam experiments lived critical-density plasma in the early This light pressure can enable the laser 1994, the Petawatt’s beam was alcoholic champagne for the historic Third, through early next summer, without impacting operation of the Nova part of the pulse. Because the petawatt pulse to interact with very-high-density propagated to Nova’s two-beam target night. (See Figure 4.) the laser can be used as the core of a chamber.” pulse is so short, the plasma does not material at the core of an imploded bay to study CPA effects. For the second 100-trillion-watt laser to study plasma The 100-TW laser was constructed in have time to expand during the pulse. fusion pellet instead of being stopped shot series, performed in March 1995, the Four Options physics and begin research on fast- early 1995 as a crucial stepping stone to The remainder of the pulse then reflects by lower-density plasma in the corona. beam was propagated into the newly As the Petawatt laser is now ignitor physics. Finally, early this the Petawatt. Using most of the off the critical-density plasma and These intense pulses also generate large constructed compression chamber to configured, the beamline from the winter, a target chamber will be Petawatt’s components, but not taking strikes the target of interest. amounts of energetic electrons. These advantage of the full complement of The resulting detonation of the target high-intensity phenomena form the Nova’s amplifiers, the 100-TW is creates a large amount of debris (typical basis of the patented fast-ignitor fusion connected to Nova’s two-beam target of all target experiments) that hits the concept. (See Figure 6.) area. It was successfully test fired for the plasma mirror substrate instead of In this scheme, laser energy first time on July 31, 1995, surpassing sensitive and expensive diagnostic compresses a spherical volume of Figure 4. The Livermore the 120 trillion watts produced by Nova equipment and optics. (See Figure 5 for fusion fuel to high density—exactly as crew after the first and making it the most powerful laser the difference in optical- and plasma- in the conventional approach to ICF. successful ever tested at the time. mirror irradiances.) The curvature of the However, conventional ICF relies on accomplishment of “The 100-TW was only a warm-up mirror can be easily changed to the formation of a hot central core petawatt peak power for the Petawatt,” says project engineer (1,250 trillion watts) on Greg Tietbohl, noting that the laser has May 23, 1996. been used to test some of the basic 125 concepts and advanced components 80 underlying the Petawatt. Laser–plasma 138 experiments being performed on the 100- TW laser are producing data that enable 150 the design of a more comprehensive 100 series of experiments to test the fast-

ignitor concept on the Petawatt. The 100- Micrometers 162 TW laser continues to operate as the 120 world’s second most powerful laser, and 175 it is now used extensively by researchers from LLNL and the international university community. The 100-TW 150 162 175 188 200 140 160 180 200 operations will end in July 1997 because Micrometers Micrometers Nova’s two-beam target bay will be Figure 5. False-color contour plot of far-field irradiance distributions from disassembled in order to build an optics (a) a precision optical mirror (diffraction-limited spot) and (b) a plasma mirror. assembly area for NIF.

Science & Technology Review December 1996 Science & Technology Review December 1996 10 Petawatt Petawatt 11

the core to over 100 million degrees instead of many kilometers as in information to Lawrence Livermore Conventional ICF Celsius. The fusion burn propagates conventional particle accelerators. scientists supporting DOE’s Stockpile from this small volume on the edge The enormous electric fields created Stewardship and Management Program. throughout the remaining fuel before by the Petawatt will impart enormous The Petawatt laser is currently Laser energy hydrodynamic disassembly of the core. oscillatory (“quiver”) energy to the free undergoing a long series of tests as it is The fast-ignitor technique offers, in electrons in the plasma. At 1021 W/cm2, transformed into an operational facility Inward transported principle, a method of reducing the the quiver energy of a free electron for target experiments. Its development is thermal energy energy and precision required to would be more than 10 million electron expected to continue into the next decade Thermonuclear burn Ignition Burn achieve ignition compared with volts. The electrons would be moving at as LLNL scientists continue to advance conventional ICF. Perry cautions that, speeds approaching the speed of light the state of the art in optics and the Blowoff During the final Thermonuclear burn compared with the firm scientific and at densities never before seen in the technology of short-pulse lasers. Perry part of the implosion, spreads rapidly through the fuel core reaches the compressed fuel, foundation of conventional ICF, the laboratory. notes that several years of hard work lie 20 times the density yielding many times fast-ignitor concept is still in its infancy These plasmas will be similar to those ahead in exploring the fast-ignitor of lead and ignites the driver input energy. because it resides in a region of untested believed to exist in many astrophysical concept with the Petawatt. The overall at 100,000,000°C. physics. If, however, upcoming fast- objects. Scientists could then study goal, as it was with the development of ignition tests prove successful, a conditions predicted to exist in the center Livermore’s first generation of lasers, is petawatt laser could be added to the NIF of stars and surrounding celestial bodies to speed the arrival of laser fusion as a for fast-ignitor capability at a moderate such as black holes and brown dwarves. source of virtually inexhaustible energy additional cost. Additionally, high-energy photons for society. Another goal, admittedly Fast-Ignitor ICF The Petawatt’s beam would be fired (0.1 to 10 megaelectron volts) produced closer at hand, is to aid the nation’s to inject energy into a small region of from the interaction of the petawatt pulse Stockpile Stewardship Program. Atmosphere Compression the deuterium–tritium target capsule to with high-atomic-number targets offer formation initiate ignition a few billionths of a the potential for time-resolved Key Words: chirped-pulse amplification, fast ignition, laser interference lithography, Laser or particle Fuel is compressed by second after NIF’s beams are fired. A radiography of dense objects. The short- Petawatt–NIF combination might pulse duration, potentially small source multilayer dielectric gratings, National beams rapidly rocket-like blowoff of Ignition Facility, Nova, Petawatt laser, plasma heat the surface the surface material. Ignition Burn enable the achievement of a higher size, and simple production of multiple mirror, Ti:sapphire laser, 100-TW laser. of the fusion target, fusion energy gain than currently pulses separated in time make this an forming a surrounding At the moment of Thermonuclear envisioned. attractive source for multiple-exposure For further information contact plasma envelope. maximum compression burn spreads rapidly flash x-ray radiography. The plasmas Michael Perry (510) 423-4915 a short (1 to 10 pico- through the compressed A New Chapter in Physics themselves can provide important ([email protected]). seconds), high-intensity fuel, yielding many times The ultrashort pulses and extremely (1020 watt/centimeter2) the driver input energy. Figure 6. Contrast of conventional pulse ignites the capsule. high irradiance of the Petawatt laser inertial confinement fusion (ICF) and the will also enable researchers to advance About the Scientist fast-ignitor ICF, which is used on the their understanding of laser–matter Petawatt laser. interactions and, indeed, advance MICHAEL PERRY joined Lawrence Livermore National understanding of the fundamental Laboratory as a physicist in October 1987. He is a graduate of nature of energy and matter. The the University of California at Berkeley with a B.S. in both enormous irradiance that will be nuclear engineering and chemical engineering (Summa Cum 21 within the dense deuterium–tritium fuel substantial energy and precision from Petawatt laser bores through the plasma generated by the Petawatt, some 10 Laude, 1983), an M.S. in nuclear engineering (1984), and a 2 to spark ignition. This condition is the laser. and pushes the deuterium–tritium fuel in W/cm , will make possible an Ph.D. in nuclear engineering/physics (1987). He is currently achieved by the rapid, highly By contrast, the fast-ignitor concept its path toward a higher density near the irradiance unlike any produced in the the leader of the Petawatt Laser Project and Associate Program symmetrical and spherical implosion of adds two laser beams that are timed to core of the target. At the optimum laboratory to date. These unprecedented Leader for Short-Pulse Lasers, Applications, and Technology. the capsule driven by pulses delivered strike the target at the moment of moment, a petawatt ignitor beam laboratory conditions will be He has authored more than 70 professional publications. either directly by many laser beams or maximum compression. Because the propagates through the channel formed characterized by electric fields about indirectly by x rays. Because of the Petawatt was conceived to use Nova, by the channeling beam, striking the 100 times stronger than the field that extreme requirements on symmetry and eight of Nova’s ten beamlines would high-density, preimploded core. The binds electrons to atomic nuclei. Such the necessity to achieve both high strike the target and form a plasma. petawatt pulse generates hot, high- fields have the potential to trap temperature and density in the Then a 1-TW, 100-picosecond energy electrons, which instantaneously electrons and accelerate them to high implosion, conventional ICF requires channeling beam supplied by the raise a small region on the periphery of energies within just a few centimeters,

Science & Technology Review December 1996 Science & Technology Review December 1996 12 13

Dismantlement High Explosives in Stockpile Development Production Stockpile maintenance Retirement (Early in production) Screening tests • Chemical reactivity tests Accelerated aging tests Stockpile laboratory tests • Weight loss New materials laboratory tests Surveillance Indicate Constancy • Coupon tests Core test unit Accelerated core Shelf storage units sample tests Long-term storage units Livermore actively seeks to improve the analysis of high explosives in stockpiled nuclear

weapons, keeping in mind the purposes of traditional surveillance: to look for defects in Figure 1. Phases of evaluation in stockpile surveillance. materials and processes, to monitor indicators of both constancy and change, and to confirm that design choices did not cause problems. detonate on demand but difficult to detonation. The choice of binder affects HMX is more energetic than RDX but explode accidentally. The explosive hardness, safety, and stability. retains good chemical and thermal should also be compatible with all Too brittle a PBX can sustain stability, important for long-term the materials it contacts, and it damage in normal handling and storage and survival in extreme should retain all its desirable succumb to extreme temperature swings environments. Sensitivity of any PBX NY weapon in the U.S. nuclear Stockpile Evaluation weapon’s components caused by aging qualities indefinitely. or thermal shocks, while too soft a PBX is a complex characteristic strongly A arsenal, if ever deployed, must “Stockpile surveillance” is the third, or environmental factors. Simply No such explosive existed in 1944. may be susceptible to creep and may affected by HE particle size work exactly as intended. Americans or maintenance, phase of a spectrum of because nothing is wrong, the inference While using what was available to lack dimensional stability or strength. distribution, viscoelastic properties, expect that assurance even though special tests that begins during a cannot be made that the weapon will meet wartime demands, scientists at To achieve safe and stable PBXs, the binder-to-HE wetting, and storage international relations since 1989 have weapon’s design and ends only with its last indefinitely. Livermore’s Enhanced Los Alamos began to develop a high- Laboratory uses two main charge environment. Only the TATB-based brought dramatic and fundamental retirement from the stockpile (see box Surveillance Program is currently energy, relatively safe, dimensionally explosives based on HMX and TATB.† formulations (Figure 2) of Livermore’s changes to the U.S. nuclear weapons on p. 13 and Figure 1). Such tests now examining concepts that improve stable, and compositionally uniform program. Responsibility for assuring are the principal means of evaluating predictive capabilities. explosive. By 1947, scientists at Los reliability, performance, and safety of the condition of U.S. nuclear weapons. Should problems appear, the Alamos had created the first plastic- the nuclear weapons stockpile belongs For this phase, stockpile laboratory tests increasing body of data will guide the bonded explosive (PBX), an RDX*- HE’s Role in a Nuclear Weapon to the nuclear design and production provide “indicators of constancy” program to accommodate or eliminate polystyrene formulation later community, which conducts the wide through comparison with baseline data adverse effects. Old or damaged parts designated PBX 9205. Although The nuclear explosive package includes nuclear and non-nuclear components that range of activities in the Department of gathered during weapon development are replaced or upgraded before a other PBXs have since been comprise a primary explosive device and a secondary, both enclosed within a Energy’s New Material and Stockpile and production. weapon is reassembled for the successfully formulated for a wide radiation-proof case. A key component of a primary is typically a shell of fissile Evaluation Program. Stockpile laboratory tests usually stockpile. This aspect of surveillance range of applications, only a handful material—the pit—to be imploded by a surrounding layer of chemical high explosive (HE) termed the main charge. Although stockpile evaluation is not begin during the third or fourth year resembles keeping a stored car in have displayed the combination of Stockpile evaluation requires a comprehensive battery of tests that addresses all new, methods and tests have undergone after the weapon’s production begins. driving condition. Regular inspections adequate energy content, mechanical functional aspects of a weapon throughout its so-called stockpile-to-target sequence, marked changes since the program’s Sample weapons removed from the can spot signs of damage or properties, sensitivity, and chemical stopping short of actual detonation with nuclear yield. Although the moratorium on inception almost four decades ago. stockpile are dismantled, components deterioration before they become too stability required for stockpile underground nuclear testing has precluded detonating a stockpile weapon to assess its Today, each of the participating are inspected and tested, and then the costly to repair. The vehicle can also be nuclear weapons. Since the 1960s, reliability, performance, and safety, stockpile evaluation is working to provide an national laboratories—Lawrence weapons are reassembled and restored upgraded by installing improved Livermore has been researching and adequate alternative route to the same goal of reliability assessment. Livermore, Los Alamos, and Sandia—is in the stockpile. Increasingly, replacement parts. developing safer HE for Livermore- The HE clearly plays a role vital to proper weapon function, but many questions responsible for the extensive and surveillance activities have focused on designed weapons. surround the long-term stability of the complex organic molecules of which the HE is rigorous tests to evaluate the portions one central question: How can a High Explosives The plastic coating that binds the composed. To provide assurance that stockpile quality is maintained, Livermore’s and components of the stockpile weapon’s useful service life be The ideal high-energy explosive explosive granules, typically 5 to Stockpile Evaluation team develops diagnostic tests that are performed on the HE in weapons that each has designed. This predicted? must balance different requirements. 20% of each formulation by weight, the main charges of stockpile weapons. overview of Livermore high-explosives In addition to checking for materials HE should be easy to form into parts is what gives each PBX its distinctive (HE) tests of nuclear stockpile weapons and production defects, stockpile but resistant to subsequent deformation characteristics. Pressing a PBX illustrates the degree of assurance surveillance involves monitoring through temperature, pressure, or molding powder converts it into a * RDX is 1,3,5-trinitro-1,3,5-triazacyclohexane. toward which the laboratories work. potentially damaging changes to a mechanical stress. It should be easy to solid mass, with the polymer binder † HMX is 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane; providing both mechanical rigidity TATB is 1,3,5-triamino-2,4,6-trinitrobenzene. See S&TR, November and reduced sensitivity to accidental 1996, for more information on TATB.

Science & Technology Review December 1996 Science & Technology Review December 1996 14 Stockpile Surveillance Stockpile Surveillance 15

LX-17 and Los Alamos’s PBX 9502 are The complete evaluation entails growth and density gradients, In both stockpile laboratory tests show an apparent stiffening of the Tests of Chemical considered “insensitive” high explosives four major investigations, each with thermomechanical integrity, initiation and accelerated aging tests, density LX-17 with age (see Figure 4). Characteristics (IHE); others are termed “conventional.” rigorous safety and technical protocols: capability, detonation performance, distribution is measured using cored Although this phenomenon may actually As HE ages or degrades, its (1) examining the HE for changes in sensitivity, and safety. samples. These measurements are then reflect an increase in the crystallinity of compatibility with other materials in the Evaluating the Package appearance and texture, including These concerns are addressed during compared with recorded densities from the binder, the LX-17 continues to be primary may suffer. Thus, several types Livermore is responsible for surface discoloration, cracks (using dye the warhead’s development and early each material lot. Laboratory test results monitored and will be compared with of analysis are employed to evaluate the surveillance of the stockpile weapons penetrant), or tackiness of any materials; production phases, largely through tests show that accelerated aging conditions the behavior in other systems. HE’s chemical composition. that are based on its own designs. The (2) measuring physical and mechanical using accelerated aging techniques do not significantly alter the uniformity Engineering Directorate and the Defense (tensile, compressive) properties, (primarily elevated temperature) to of HE density; density actually and Nuclear Technologies Directorate including density and contour; simulate the long-term effects of internal becomes more uniform throughout the (a) collaborate on Livermore’s Stockpile (3) measuring chemical properties, and external environment. The main goal main charge. 10 Surveillance Program. General including HE and binder composition, of accelerated aging tests is determining 8 procedures for the annual evaluation binder molecular weight, and whether materials, parts, and assemblies Tests of Mechanical Properties Microstrain begin with a predetermined number of warhead atmosphere analysis; and are compatible with each other and retain As an integral part of the explosive 6 samples of each weapon type chosen at (4) conducting performance tests, their essential properties. package’s structure, HE must retain its 5,000 4,000 random from the stockpile. All are including pin hydrodynamic tests, During surveillance, actual aging and own structural integrity. Therefore, 4 disassembled to varying degrees for “snowball” tests, and detonator test environmental effects are evaluated, tensile and compressive mechanical 3,000 evaluation, but typically only one firing or disassembly. using new materials laboratory tests and properties of HE are monitored (see 2 2,000

weapon has its explosive package In characterizing materials, material qualification test results as Figure 3). These mechanical properties Compressive stress, MPa 1,000 reduced to its component parts: pit, Livermore surveillance addresses baseline data. were found to be correlated with HE 0 explosive, detonators, and secondary. interrelationships among components. composition and density, as well as the (b) Livermore mechanical engineers and Environmental factors such as Tests of Physical Properties crystallinity and nature of the polymeric 10 materials scientists develop prototype radiation, heat, and chemical Density and density uniformity are binder. Mechanical properties may also tests, and then Pantex workers perform incompatibility can affect the behavior parameters easily measured with high be affected by changes in the properties 8 the tests on actual stockpile weapons of components and their interfaces precision. If HE chemical and density of the explosive–binder interface, but components and materials. The tests throughout the initiation chain: the distributions remain substantially these can only be addressed indirectly. 6 focus on what would alter the estimated detonator, booster, and main charge. constant during storage, no significant Tensile strength testing. Tensile minimum warhead life or require Explosives could also suffer aging change is expected in specific energy or tests are performed on LX-17, for 4 retrofitting. effects in such properties as creep, detonation velocity. example, at a low temperature (–20°C) 2

and a slow rate because these Compressive stress, MPa conditions simulate the expected worst 0 case (due to thermal expansion (c) Figure 3. High-explosives mismatches of the materials). This test 10 chemist Mark Hoffman sets best shows differences in material up HE for mechanical tests. quality. Test data for three Livermore 8 weapon systems show no apparent aging trends in LX-17 tensile stress and 6 strain at failure. Compression testing. For 4 simulating the worst-case conditions for creep (displacement under fixed load) 2

in the warhead, compression tests are Compressive stress, MPa 0 performed on LX-17 at an elevated 0510 temperature (50°C) and a slow rate Stockpile age, years (1,440 microstrain per hour). In surveillance testing, compression Figure 4. (a) The compressive stress tests for the LX-17 high explosive recovered from the W87 Figure 2. TATB material is being prepared values for LX-17 have not failed or new materials laboratory test (NMLT) units and stockpile laboratory test (SLT) units. The data for an aging test. fallen outside of material qualification show a stiffening of the LX-17 at all strain levels, which may be consistent with a gradual limits. Data on stockpile-aged material increase in the crystallinity of the Kel-F-800 binder. For reasons not clear at this time, this trend from the W87 warhead, however, do is not supported by the observations from the B83 (b) NMLT units and (c) SLT units.

Science & Technology Review December 1996 Science & Technology Review December 1996 16 Stockpile Surveillance Stockpile Surveillance 17

Chemical composition analysis. any, remain too subtle for current changes in molecular weight that might HE. A machined shell of LX-17 is First, early in a weapon’s stockpile life, can assess effects on weapons Relative percentages of binder and HE analytic techniques. indicate the onset of degradation, assembled with a booster and detonator to materials and processes are scrutinized performance. are compared with values obtained Molecular weight analysis. For this however, are very difficult to detect and form a “snowball.” When this assembly for defects, and then they are monitored • Verifying the safety of aged materials from qualification tests of newly analysis, the polymer binder is extracted characterize. In Livermore’s Enhanced is fired, a streak camera captures spatial to confirm that design choices do not via testing and modeling. produced HE. Percentages of HE from the HE and subjected to gel Surveillance Program, methods are and temporal information of the initial, or cause problems. These changes will help improve an different from nominal values could permeation chromatography (also called being developed to improve the ability “breakout,” detonation wave on the outer Other improvements are being already successful Livermore stockpile signal significant chemical size exclusion chromatography). to detect aging effects. surface of the LX-17 snowball (see evaluated for inclusion in the program: evaluation program. They will enhance degradation, which would mean lower Current techniques have yet to reveal Warhead atmosphere gas Figure 5). The relatively flat curves at the (1) fundamental understanding of aging surveillance techniques to assure the energy density for LX-17. To date, significant aging effects on the sampling. Mass spectroscopy and gas bottom of the image data indicate a good, mechanisms in stockpile materials, nation and its armed forces that however, aging has not affected molecular weight or molecular weight chromatography of warhead gas samples uniform explosion. Changes in the (2) better selection of stockpile samples Livermore-designed weapons can be chemical composition. Changes, if distribution of LX-17 binder. Small can identify material outgassing and breakout profile would be used to track for testing and evaluation, (3) better safely stored and transported and that ongoing chemical reactions, both of the performance of the booster and the uses of available materials (stockpile- they can work exactly as intended which may indicate degradation or condition of the interface with the HE. aged materials, such as those from throughout their stockpile life. (a) decomposition of the organic Aging tests. So far, surveillance data retired and dismantled weapons), and compounds in the HE. They also help to on HE from the B83, W84, and W87 (4) peer review of surveillance data. Key Words: accelerated aging, high Figure 5. (a) A “snowball” test verify whether warhead environmental programs show no evidence of aging Accordingly, the Livermore explosive (HE), LX-17, nuclear weapon, assembly (bottom) is aligned with seals have leaked. effects. Because the W87 system must Stockpile Surveillance Program has PBX, pin-dome test, predictive capability, samples of snowball test data (top) be requalified for an additional 25 to proposed revisions in the surveillance snowball tests, stockpile evaluation, stockpile as recorded by the streak camera. Performance Tests 30 years, additional data are being mission to achieve the following surveillance, TATB. (b) The schematic shows the mirrors Performance tests tell about the gathered and analyzed to improve capabilities: that reflect the left and right sets of detonation response of the material. Pin Livermore’s long-term predictive • Detecting and identifying changes in snowball data. hydrodynamic tests check the implosion capability. Aged LX-17 is being subjected stockpile-aged materials that previous For further information about stockpile For illustration, vertical lines are reliability and performance of the main to far more comprehensive testing than surveillance methods may not have surveillance contact Anders W. Lundberg drawn between the photographic charge; “snowball” tests help determine usual for stockpile laboratory test units. In discovered. (510) 422-4263 ([email protected]). breakout record and the markers on the initiation reliability of the booster. essence, properties of control material • Predicting—not simply monitoring— For information about chemical and the snowball surface. The relatively Detonators also are test-fired, and from various sources are compared to the any identified age-induced changes in materials science in stockpile surveillance flat curves at the bottoms of the certain ones are disassembled for chemical, physical, mechanical, and materials through the use of models. contact Fran Foltz (510) 422-7829 image data indicate a good, uniform inspection and analysis. performance properties of aged LX-17 for • Providing information on aged ([email protected]) or James LeMay (510) explosion. Pin hydrodynamic test. This test signs of age-induced changes. materials to weapons designers, who 423-3599 ([email protected]). monitors changes in the implosion Changes, if any, will be studied behavior of HE. The test assembly further in the Enhanced Surveillance About the Engineer comprises three main subassemblies: a Program. Should no changes be pin-dome assembly, a mock pit, and the discovered, confidence in the projected HE. The test measures elapsed time longevity of the W87’s HE materials ANDERS W. LUNDBERG has supported nuclear weapons from initiation until the explosive drives will be scientifically supported. engineering and testing at Lawrence Livermore since 1961. He the mock pit into an array of timing A compatibility program initiated received both his B.S. and M.E. in mechanical engineering from pins, a “pin dome,” of known length and during W84 warhead production is the University of California at Berkeley in 1959 and 1961, location. The HE implodes the mock pit paying dividends by serving as a source respectively. At Livermore, he has been a project engineer and onto the timing pins, which provide data of aged materials for advanced study. group leader in the Weapons Program and the Nuclear Test about the temporal and spatial Some specimens of LX-17, UF-TATB Program; currently, he is group leader for Stockpile Surveillance uniformity of implosion. A nonuniform (ultrafine TATB) boosters, and LX-16 in the Mechanical Engineering Department. (b) implosion could indicate an HE pellets from W84 production are already View Camera View problem. Excessive density variations, being subjected to accelerated aging in a voids, or cracks in the HE, for example, weapon-like atmosphere for ten years. can disrupt the shock-wave propagation from the detonation. To date, The Next Step in LX-17 surveillance testing has observed none Surveillance of these problems in stockpile samples. Continually sought to improve the MirrorBooster Mirror Snowball test. This test checks analysis of HE in weapons in the pellet reliability of the initiation chain by stockpile, technologies must still fulfill confirming that the booster initiates the the purposes of traditional surveillance.

Science & Technology Review December 1996 Science & Technology Review December 1996 18 Research Highlights Body Motion 19

(a) (a) (b) collected, the data are of point, associating them from Visualizing Body two-dimensional image the same image frame, and planes that must still be then tracking them from Motion transformed into 3-D frame to frame so that moving images. This is movement reconstruction is hardly a simple task, logical. Additional given that each image complications come from frame from each camera changes in perspective, such (b) may contain as many as as curvatures and orientation, HEN you think about it, lots of people could use the 250,000 data points. caused by the moving object. W knowledge obtained from capturing, re-creating, and Thus, it is no surprise Yet another type of problem analyzing body motion in 3-D (three-dimensional) form. One that the key component intrudes when, on occasion, group might be specialists: orthopedic surgeons, to plan (a) A vertical line grid projected onto the face of Livermore engineer of CyberSight is its one view of a data point is surgery or physical therapy; athletes, to maximize their Robert Johnson to capture information from closely spaced points complex image- eclipsed from the common training and performance; robotic engineers, to “teach” robots along the lines results in (b) this CyberSight visualization. processing code. view of both cameras, so not how to interpret motion; and animators and video game The code transforms every data view has a stereo designers, to make their animations more realistic. Another 2-D objects into 3-D counterpart. group might be the folks who want to understand their own objects by mimicking The computational common ailments, such as repetitive motion problems or How to Get CyberSight human stereo vision. techniques for left–right tendonitis. The line grid projected onto a moving subject comes from a When we look at an matching, like the 3-D Studying body motion is not a new activity, but the data- glass slide precisely etched with parallel black lines; such slides object, each eye receives transformation technique gathering techniques for these studies have changed over the are commonly used for calibrating instrumentation optics. Other a slightly different image that imitates stereo vision, years. Currently, one common way of collecting motion data than this slide and the projector, the CyberSight system because it sees from a use principles based on the is by attaching reflective markers on a human actor at strategic components are similar to those of other motion imaging slightly different angle. The reconstruction of a facial sequence displayed as (a) a normal surface relationship between points—on shoulders, elbows, hips, knees, ankles—and then systems. Two charge-coupled device (CCD) cameras, which are This angular difference display at one-thirtieth of a second and (b) a rendered image from physical and mental videotaping the actor in motion. The video images are semiconductor image sensors, produce the video signals. To provides us with depth different perspectives processes, i.e., how stimuli digitized for computer extraction and calculation of the 3-D sense the data points, the cameras are firmly positioned a small perception. The lead to sensation. The locations of the markers. The calculated results are presented distance apart from each other to take “snapshots” from two geometric expression of depth perception has been adapted by computations imitate the human eye’s ability to pick up in graphical form, which may be plots or stick figures. While perspectives. Operated from 1 to 10 feet away, the cameras take the computer code to calculate depth, using the two views of intensity changes, make use of high-contrast features in an useful, these graphics are only coarse approximations of actual the snapshots at the standard video rate of 30 frames per each data point sensed by the stereo cameras. The computer image (such as edges and intersections), and filter or human movement. If used for animation purposes, for second. The CCD images are digitized by an image frame calculation is based on the principle of triangulation, a “smooth” received data. They also use dynamic example, they would require a great deal of rendering before grabber and stored in memory boards. From there, they are measurement technique that uses two known points to derive a programming, in which small subproblems are solved. Those they could be considered finished. For studying biomechanics, transferred to a host computer for calculation and third value. The triangulation uses the known, left–right views solutions are used to solve larger and larger subproblems their accuracy and level of detail are limited by the relatively reconstruction into 3-D computer representations that can be of an image point, the geometry of the camera arrangement, until eventually the problem itself is solved. The techniques small number of data points from which their information has presented as rendered images. baseline distance, and converging optical angles to establish result in a code with some ability to interpret “context” in been extrapolated. The sample images of a facial expression sequence in the the position of that image point in space. The figure on the performing the left–right matches and to fill in some missing Recently, Lawrence Livermore engineers Shin-Yee Lu and figure on the next page are taken from CyberSight data that next page simplifies the basis of triangulation. details, such as the eclipsed data views. Robert K. Johnson demonstrated the next step in motion were reconstructed into several perspectives. Unlike a Camera geometry is determined by means of a calibration imaging systems. Dispensing with reflective markers, Lu and conventional photograph, the images are generated from a process. During calibration, images are taken of reference Building on Past Work Johnson devised a system that detects data points on a grid of computer model of true dimensionality that can be target points with known spatial positions, and these are used The work on CyberSight follows earlier robotic motion parallel, closely spaced vertical lines that have been projected manipulated, analyzed, and visualized. This feature makes to back-calculate the camera geometry and lens parameters to studies that Lu and Johnson performed for LLNL’s in-house onto a moving object (see figure above), which is then CyberSight useful for biomechanical analyses. The complex be used for actual videotaping. Laboratory Directed Research and Development project. The captured at video speed. Motion information collected in this information will allow computer models to calculate body purpose of that work was to program robotic “hands” to way is dense, continuous, and uniform. It can be used to surfaces and volumes, determine relationships between bones Matching the Left and Right “Eyes” handle hazardous waste. The work captured the interest of produce a real-time, complex visualization of movement that and muscles, and estimate velocity and force of movements. Before the calculations for depth can be made, the left and pediatric hospitals that are seeking better ways to design is realistic enough to be pasted directly into an animation. Lu right views of the data points must be accurately matched. treatment for cerebral palsy. Their need gave Lu and Johnson and Johnson call this system CyberSight. Calculating Three-Dimensional Space This difficult, time-consuming task requires a very high By solving the problem of collecting complete, voluminous degree of computational complexity. The matching involves motion data, CyberSight has uncovered another problem. As associating the correct left and right views of the same data

Science & Technology Review December 1996 Science & Technology Review December 1996 20 Body Motion Research Highlights 21

Studying the Earth’s Formation: The Multi-Anvil(a) Press at Work Matching leftÐright data points

ANY things that scientists study are invisible to them. Optical line M Announcements about the discovery of planets around Right view other stars do not come because astronomers have seen the Left view planets, although they would certainly love to. The discovery is more likely based on observations of the star’s motion that indicate strong nearby gravitational forces. So it is with (b) Baseline Common focal point discoveries about the Earth’s core and mantle. Because the deepest well ever drilled extends down just 12 kilometers, not even pricking the mantle, researchers have to employ indirect the impetus to develop a more advanced motion imaging methods to study the Earth. Optical axis technique, and CyberSight was the result. Using meteorites and seismological evidence as clues, The most immediate applications for CyberSight are scientists have known almost since the beginning of the expected to be animation and virtual reality projects. With century that the Earth has a solid, mostly iron, inner core and A point in the object subsequent development, the CyberSight code will be a a molten outer core with a mantle and crust of rocky, silicate powerful tool with far-ranging applications from orthopedic material. But for just as long they have been puzzled about surgical planning, speech therapy, and physical therapy to how the core and mantle separated. The primordial planet security applications such as facial recognition systems. Earth grew out of bits of gas and dust, aggregating over time Figure 3. Triangulation is used in This image-processing technology could also be used in into a larger, more solid body. Was there then some the CyberSight computer code to manufacturing to provide rapid prototyping of new products cataclysmic event billions of years ago that melted much of (c) locate the data points in space. and to personalize products such as prostheses, gas masks, the planet, prompting the metals and silicates to separate as clothes, and shoes. It has potential nonhuman-related oil and water do? Or was the separation the result of a more (a) The ceramic applications as well. Surface deformations of materials could gradual process, a trickling down of the denser molten metals octahedron with the be monitored during the manufacturing process, or stress and between solid silicate mineral grains to the center of the sample material inside it strain analyses could be performed on materials and structures Earth? fits inside eight tungsten (such as vehicle air bags or the vehicle itself) to determine Recent research at Lawrence Livermore National carbide cubes that in safety and functionality. The ingenuity of the CyberSight data Laboratory by geochemist William Minarik has helped to turn sit inside (b) the split collection technique, supported by its complex computer dispel the second, “trickle down,” theory. Using the larger of cones of the multi-anvil code, portends numerous and exciting future applications. Livermore’s two multi-anvil presses to mimic the pressures press. (c) The closed and temperatures that exist deep in the Earth, he has shown press is also shown. Key Words: 3-D visualization, biomechanics, image processing, that metals like those in the Earth’s core could not have motion study, movement reconstruction. trickled down (see figure at right). The materials used in the experiments were olivine, a silicate mineral that makes up much of the Earth’s upper For further information contact Shin-Yee Lu mantle, and an iron–nickel–sulfur–oxygen combination to (510) 424-3796 ([email protected]) or Robert K. Johnson represent the core. (510) 422-8375 ([email protected]). The multi-anvil press is a relatively rare research tool. Livermore’s two presses have been used for a variety of material property studies, including diffusion and deformation of ceramics and metals, deep-focus earthquakes, and the high- pressure stability of mineral phases. The larger, 1,200-ton hydraulic press can produce pressures of

Science & Technology Review December 1996 Science & Technology Review December 1996 22 Earth Core Studies Earth Core Studies 23

steel buckets as shown in the figure on p. 21. In several stages, Livermore scientists have long studied material properties the steel buckets pushed on the carbide cubic anvils, which and the effects of high temperatures and pressures. Their work pushed on the octahedral volume inside. has resulted in some mighty big bangs but none as large as the The multi-anvil press is not Livermore’s only device for ones Minarik has postulated. studying the behavior of the Earth’s innards, but in many ways “We plan to look next at the geochemical aspects of this it is the best for this type of study. The diamond-anvil cell can project, the partitioning of trace elements between molten produce 100-GPa pressures, comparable to the pressures at the metal and silicates at the same high temperatures and center of the Earth (see Science & Technology Review, March pressures,” says Minarik. “There are many scientists in this 1996). But it can accommodate only a 20-micrometer sample, country and elsewhere studying the formation of the Earth, too small for much post-experiment evaluation. With the and all of us are in the same boat. With all of the direct piston-cylinder press, the sample volume is about evidence of the Earth’s formation buried far beneath our feet, 500 millimeters3, but it has only a 4-GPa pressure capability, these laboratory experiments are our only way to recreate which is comparable to a depth of just 120 kilometers. The what might have happened.” multi-anvil press is in the middle, providing pressures useful for studies of this type and accommodating a sample large Key Words: Earth core formation, multi-anvil press. enough for evaluation after the experiment. In Minarik’s experiments, the press took about 4 hours to References bring the samples to full pressure, after which the samples 1. W. G. Minarik, et al., “Textural Entrapment of Core-Forming Melts,” Science 272, 530–533 (April 26, 1996). were heated for periods ranging from 4 to 24 hours. During this time, the porosity of the sample collapsed, and the stable microstructure developed. Then the unit was cooled down For further information contact and allowed to decompress for about 12 hours. During this William Minarik (510) 423-4130 process, the graphite capsule turned to diamond, which must ([email protected]) or be ground off before the sample could be sliced and polished Frederick Ryerson (510) 422-6170 A 30-micrometer-thick slice of 25 gigapascals (GPa), which is equivalent to 250,000 times the for evaluation. ([email protected]). an experiment sample in atmospheric pressure at sea level, or the pressure that occurs Despite being molten and much denser than the olivine, the double exposure. The field of 700 kilometers deep in the Earth. In addition to pressing on the metallic melt showed no signs of separating and draining to view is about 500 micrometers. sample, the experiment passes an electric current through a the bottom of the capsule. For the molten metal to drip down Transmitted light reveals the furnace within the assembly to generate temperatures up along the silicate grain edges, it has to be able to wet the colorful olivine grains, while to 2,200°C. edges. But in none of the experiments did wetting occur.1 light reflected from the top These experiments using the multi-anvil press generated a Rather, the iron–nickel mixture beaded up at the corners of the shows the brown sulfides at the high pressure of 11 GPa, or 110,000 times the atmospheric silicate grains like water does on a waxed car, as shown in the corners of the olivine grains. pressure at sea level. This corresponds to 380 kilometers deep figure on p. 22. The sulfides have not wetted into the Earth, or pressures at the center of moons or asteroids Livermore’s findings agree with similar, lower-pressure the edges of the olivine grains. 2,500 kilometers in radius (about the size of Mercury). The studies that have melted meteorites and iron–nickel–sulfur– Oxides appear black. sample was also heated to a temperature of 1,500°C. Under oxygen mixtures and failed to wet the silicate minerals. those conditions, the metal melts and the olivine remains solid. Together, these experiments indicate that much higher The geometry of the press is key to creating these enormous temperatures were required to separate the Earth’s core and pressures. For the 11-GPa experiment, a ceramic octahedron mantle—temperatures high enough to melt most of the Earth. had a 10.3-millimeter-long hole with a tiny rhenium furnace, a All of these data lend credence to the theory that the young, thermocouple to measure temperatures, and a graphite capsule growing Earth was repeatedly bombarded by large planetoids, containing the olivine and iron–nickel–sulfur–oxygen sample with some of these collisions generating temperatures high inserted in it. The octahedron rested in the center of eight enough to form a magma ocean from which drops of dense 32-millimeter tungsten carbide cubes whose inside corners molten metal separated. The largest collision may have been were truncated to accommodate the sample. (Tungsten carbide when a large celestial body, about the size of Mars, collided is used for the cubes, or anvils, because of its hardness, which with Earth nearly 4.5 billion years ago, melting most of it and is close to that of diamonds but at a much lower cost.) Tiny causing the core and mantle to separate. The leading theory ceramic gaskets were placed at the edges of the carbide cubes today for the Moon’s formation postulates that some material to contain the pressure. This assembly of an inner octahedron from that collision was ejected into orbit and condensed into and eight carbide anvil cubes was put in the press’s split-cone, the Earth’s Moon.

Science & Technology Review December 1996 Science & Technology Review December 1996 Each month in this space we report on the patents issued to and/or 24 Patents and Awards the awards received by Laboratory employees. Our goal is to Patents and Awards 25 showcase the distinguished scientific and technical achievements of our employees as well as to indicate the scale and scope of the work done at the Laboratory. Patents

Patent issued to Patent title, number, and date of issue Summary of disclosure Patent issued to Patent title, number, and date of issue Summary of disclosure

James L. Kaschmitter Three-Dimensional Amorphous Solar cells that use deep (high-aspect-ratio) p and n contacts to create Gary E. Sommargren Phase Shifting Diffraction An interferometer having the capability of measuring optical Silicon/Microcrystalline Silicon Solar Cells high electric fields within the carrier collection volume material of the cell. Interferometer elements and systems with an accuracy of ¬/1,000, where ¬ is the The deep contacts are fabricated using repetitive pulsed laser doping so wavelength of visible light. This interferometer uses an essentially U.S. Patent 5,538,564 as to create the high-aspect p and n contacts. The provision of the deep U.S. Patent 5,548,403 perfect spherical reference wavefront generated by the fundamental July 23, 1996 contacts that penetrate the electric field deep into the material where the August 20, 1996 process of diffraction. The interferometer is adjustable to give unity high strength of the field can collect many of the carriers results in a high- fringe visibility, which maximizes the signal to noise and has the efficiency solar cell. means to introduce a controlled, prescribed relative phase shift between the reference wavefront and the wavefront from the optics Gerald W. Coutts Mass Spectrometer Vacuum Housing and A vacuum housing that is composed of cleaned and welded stainless- under test. John F. Bushman Pumping System steel tube components and includes flanges sealed with metal gaskets. Terry W. Alger The housing is broadly composed of two interconnected tubular William J. Benett Monolithic Microchannel Heatsink A silicon wafer that has slots sawed in it that allow diode laser bars U.S. Patent 5,539,204 sections (each section having a flange at the outer end and at the main Raymond J. Beach to be mounted (soldered) in contact with the silicon. Microchannels July 23, 1996 body section). The vacuum pumps require simple and minimal electrical Dino R. Ciarlo U.S. Patent 5,548,605 are etched into the back of the wafer to provide cooling of the diode controls and use minimal electrical power. These attributes allow August 20, 1996 bars. The channels are rotated from an angle perpendicular to the packaging into a small, lightweight volume that will operate with minimal diode bars, allowing increased penetration between the mounted power. diode bars. Low thermal resistance of heatsinks allow high average power operation of two-dimensional laser diode arrays. Charles L. Bennett Method for Determining and Displaying An imaging Fourier transform spectrometer employing an interferometer the Spatial Distribution of a Spectral coupled to a digital framing camera. Output from the digital framing Troy W. Barbee, Jr. Method for Fabricating an Ignitable Method for fabricating a multilayer structure with selectable Pattern of Received Light camera is provided to a computer that, by manipulation of that data, can Timothy Weihs Heterogeneous Stratified Metal features: propagating reaction front velocity V, reaction initiation display a two-dimensional representation of measured spectra and/or Structure temperature attained by application of external energy, and amount U.S. Patent 5,539,518 numerical data pertaining to those spectra. The digital framing camera is of energy delivered by a reaction of alternating unreacted layers of July 23, 1996 optically and electrically coupled to the output of the interferometer such U.S. Patent 5,547,715 the multilayer structure. Because V is selectable and controllable, a that an interferogram is recorded at precise intervals in synchrony with August 20, 1996 variety of different applications for the multilayer structures are the movement of the moving mirror of the interferometer. possible, including use as ignitors, in joining applications, in fabrication of new materials such as smart materials, and in medical William F. Krupke Transition-Metal-Doped Sulfide, Selenide, A new class of solid-state laser crystals and lasers that are formed of applications and devices. Ralph H. Page and Telluride Laser Crystal and Lasers materials that have fourfold coordinated substitutional sites. The host Laura D. DeLoach crystals include II-VI compounds that are doped with a transition metal Karla Hagans Self-Tuning Method for Monitoring A method using a tunable laser for determining the density of a gas Stephen A. Payne U.S. Patent 5,541,948 laser ion (e.g., chromium, cobalt, or iron). Important aspects of these Leon Berzins the Density of a Gas Vapor vapor component that absorbs light at an expected maximum July 30, 1996 laser materials are the tetrahedral site symmetry of the host crystal, low Joseph Galkowski Component Using a Tunable Laser frequency. A laser is tuned to transmit a laser source beam at a excited-state absorption losses, high luminescence efficiency, and the Rita Seng local maximum absorptance frequency of the component by d4 and d6 electronic configurations of the transition metal ions. U.S. Patent 5,550,636 transmitting at last one laser source beam through at predetermined August 27, 1996 path of gas vapor. The frequency of the laser source beam is swept Ravindra S. Upadhye Clean Process to Destroy Arsenic- A process using a reducing agent to decompose an organic compound through a frequency range, including the expected maximum Francis T. Wang Containing Organic Compounds with containing arsenic. The reducing agents may include alkali metals, absorptance frequency. Recovery of Arsenic alkaline earth metals, hydrides, and hydrogen gas. In the case of a pure metal reducing agent, an intermediate metal arsenide is formed that may U.S. Patent 5,545,800 be acidified to form an arsenic-containing gas, such as arsine. The August 13, 1996 arsine gas is then reduced to pure arsenic by a thermal or chemical process. This reduction process avoids the costly separation or disposal Awards of arsenic oxide. Laboratory scientists Bruce Hammel and Laurance Suter have Group in the Theory and Target Design (X) Division of the Laser been elected fellows by the American Physical Society. Their Programs Directorate and is working on a new type of source for Don E. Fischer Crimp Sealing of Tubes Flush With or An apparatus used when a ductile metal tube and valve assembly are election brings to 30 the number of APS fellowships earned by the producing x rays with high-powered lasers for the future National Don Walmsley Below a Fixed Surface attached to a pressure vessel that has a fixed surface around the base of Laboratory’s Inertial Confinement Fusion Program in the last Ignition Facility. P. Derek Wapman the tube at the pressure vessel. A flat anvil is placed against the tube, die 20 years. U.S. Patent 5,546,783 guides are placed against the tube on a side opposite the anvil, and a The citation on Hammel’s certificate reads “for measurements Sixteen organizations were awarded the 1996 DOE Energy August 20, 1996 pinch-off die is inserted into the die guides against the tube. Adequate and understanding of x-ray-driven hydrodynamic instabilities and Quality Awards in October, including Livermore’s Business Services Department, in recognition of substantial achievement in quality clearance for inserting the die and anvil around the tube is needed below x-ray drive asymmetry.” Hammel is currently head of experimental research within the ICF Program and is responsible for experiments management. the fixed surface. The anvil must be flat, so that, after crimping, it may be on the Nova laser. “These award winners have demonstrated excellence in removed without deforming the crimped tubes. Suter was cited for “pioneering work and leadership in the ‘reinventing government’ in support of the President’s National design, modeling, and analysis of experiments using laser-heated Performance Review principles: putting customers first, cutting red Malcolm Caplan Vacuum-Barrier Window for Wide- A vacuum output window that comprises a planar dielectric material with hohlraums that quantify and control x-ray drive, symmetry, and tape, empowering employees, and getting back to basics,” said DOE Clifford C. Shang Bandwidth High-Power Microwave identical systems of parallel ridges and valleys formed in opposite pulse-shaped implosions.” He is currently the leader of the Hohlraum Secretary Hazel O’Leary. Transmission surfaces. The valleys in each surface neck together along parallel lines in the bulk of the dielectric. Liquid-coolant conduits are disposed linearly U.S. Patent 5,548,257 along such lines of necking and have water or liquid nitrogen pumped to August 20, 1996 remove heat. The ridges focus the incident energy in ribbons that squeeze between the liquid-coolant conduits without significant losses over very broad bands of the radio spectrum. Science & Technology Review December 1996 Science & Technology Review December 1996 26 Abstracts 1996 Index 27

Crossing the Petawatt Threshold High Explosives in Stockpile Surveillance Science and Technology Review Page Indicate Constancy A revolutionary new laser called the Petawatt, developed January/February 1996 by Lawrence Livermore researchers after an intensive three- Although stockpile evaluation is not new, methods and The Laboratory in the News 2 Patents and Awards 4 year development effort, has produced more than tests have undergone marked changes since the program’s Commentary on Environmental Restoration 5 1,000 trillion (“peta”) watts of power, a world record. By inception almost four decades ago. Today Lawrence Features crossing the petawatt threshold, the extraordinarily powerful Livermore, Los Alamos, and Sandia National Laboratories are Groundwater Cleanup Using Hydrostratigraphic Analysis 6 laser heralds a new age in laser research. Lasers that provide responsible for the extensive and rigorous tests to evaluate the Micropower Impulse Radar 16 a petawatt of power or more in a picosecond may make it portions and components of the stockpile weapons that each Research Highlights possible to achieve fusion using significantly less energy has designed. An overview of Livermore high-explosives tests Probing with Synchrotron-Radiation-Based Spectroscopies 30 than currently envisioned, through a novel Livermore of components in nuclear stockpile weapons illustrates the Operating a Tokamak from across the Country 32 concept called “fast ignition.” The petawatt laser will also degree of assurance that the laboratories work toward. March 1996 enable researchers to study the fundamental properties of Evaluation includes tests for changes in physical properties, The Laboratory in the News 2 matter, thereby aiding the Department of Energy’s Stockpile mechanical properties with tensile and compression tests, and Commentary on Industrial Ecology 4 Stewardship efforts and opening entirely new physical performance with pin-dome, “snowball”, and aging tests. Features regimes to study. The technology developed for the Petawatt Looking toward the future, the program is working to improve The Safe Disposal of Nuclear Waste 6 has also provided several spinoff technologies, including a predictive capabilities so that weapons designed at Livermore The Diamond Anvil Cell: Probing the Behavior of Metals under Ultrahigh Pressures 17 new approach to laser material processing. can safely be stored and work exactly as intended throughout Research Highlights ■ Contact: their stockpile life. Getting along without Gasoline—The Move to Hydrogen Fuel 28 Patents 32 Michael Perry (510) 423-4915 ([email protected]). ■ Contact: Anders W. Lundberg (510) 422-4263 ([email protected]). April 1996 The Laboratory in the News 2 Patents 3 Commentary on Laboratory Directed Research and Development 5 Features MACHO: Collaboration Is Key to Success 6 A New Look at an Old Idea—The Electromechanical Battery 12 Research Highlights Graffiti-Removal by Laser 20 Adding Agility to Manufacturing 22

May 1996 The Laboratory in the News 2 Commentary on ES&H Technology 3 Features Mitigating Lightning Hazards 4 Groundwater Modeling: More Cost-Effective Cleanup by Design 13 Dual-Band Infrared Computed Tomography: Searching for Hidden Defects 23 Research Highlights Plating Shop Moves to Finish Off Waste 28 Patents 31

June 1996 The Laboratory in the News 2 Patents and Awards 4 Commentary on Materials Modeling and Stockpile Stewardship 5 Features Theory and Modeling in Materials Science 6 LLNL and DOE Collaborate on Successful Fusion Facility Cleanup 14 Research Highlights Solving the Mammoth Mountain CO2 Mystery 20 A Closer Look at Osteoporosis 22

Science & Technology Review December 1996 Science & Technology Review December 1996 28 29

July 1996 November 1996 The Laboratory in the News 2 The Laboratory in the News 2 Commentary on the University Relations Program 3 Commentary on Countering Terrorism with Computers 3 Features Features Frontiers of Research in Advanced Computations 4 Simulations to Save Time, Money, and Lives 4 The Multibeam Fabry–Perot Velocimeter: Efficient Measurement of High Velocities 12 The Secrets of Crystal Growth 12 Research Highlights Research Highlights High-Tech Tools for the American Textile Industry 20 Addressing a Cold War Legacy with a New Way to Produce TATB 21 Rock Mechanics: Can the Tuff Take the Stress? 24 DNA Sequencing: The Next Step in the Search for Genes 24 Patents 27 Patents and Awards 27

August 1996 December 1996 The Laboratory in the News 2 The Laboratory in the News 2 Commentary on Stockpile Stewardship 4 Commentary on Opportunities for Science from the Petawatt Laser 5 Features Features Keeping the Nuclear Stockpile Safe, Secure, and Reliable 6 Crossing the Petawatt Threshold 4 Research Highlights High Explosives in Stockpile Surveillance Indicate Constancy 12 Molten Salt Takes the Bang out of High Explosives 16 Research Highlights Security Clearances Meet the Electronic Age 18 Visualizing Body Motion 20 Exploring Oil Fields with Crosshole Electromagnetic Induction 24 Studying the Earth’s Formation: The Multi-Anvil Press at Work 23 Patents and Awards 24 Patents and Awards 26

September 1996 The Laboratory in the News 2 Commentary on the Next Frontiers of Advanced Lasers Research 3 Features Taking Lasers beyond the National Ignition Facility 4 Jumpin’ Jupiter! Metallic Hydrogen 12 Research Highlights Modeling Human Joints and Prosthetic Implants 19 Patents and Awards 24

October 1996 The Laboratory in the News 2 Patents 4 Commentary on the Importance of Climate Change 5 Features Assessing Humanity’s Impact on Global Climate 6 Research Highlights Livermore Wins Six R&D 100 “Oscars” 14 Electronic Dipstick Signals New Measuring Era 16 Signal Speed Gets Boost from Tiny Optical Amplifier 18 SixDOF Sensor Improves Manufacturing Flexibility 20 A Simple, Reliable, Ultraviolet Laser: the Ce:LiSAF 22 Giant Results from Smaller, Ultrahigh-Density Sensor 24 Thinner Is Better with Laser Interference Lithography 26

© 1996. The Regents of the University of California. All rights reserved. This document has been authored by the The Regents of the University of California under Contract No. W-7405- ENG-48 with the U.S. Government. To request permission to use any material contained in this document, please submit your request in writing to the Technical Information Department, Publication Services Group, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551, or to our electronic mail [email protected] .

This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California and shall not be used for advertising or product endorsement purposes.

U.S. Government Printing Office: 1996/583-059-60006

Science & Technology Review December 1996 Science & Technology Review December 1996