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Your search keyword '"Loomis Eric N."' showing total 11 results
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11 results on '"Loomis Eric N."'

1. First downscattered neutron images from Inertial Confinement Fusion experiments at the National Ignition Facility

Author

Guler Nevzat, Aragonez Robert J., Archuleta Thomas N., Batha Steven H., Clark David D., Clark Deborah J., Danly Chris R., Day Robert D., Fatherley Valerie E., Finch Joshua P., Gallegos Robert A., Garcia Felix P., Grim Gary, Hsu Albert H., Jaramillo Steven A., Loomis Eric N., Mares Danielle, Martinson Drew D., Merrill Frank E., Morgan George L., Munson Carter, Murphy Thomas J., Oertel John A., Polk Paul J., Schmidt Derek W., Tregillis Ian L., Valdez Adelaida C., Volegov Petr L., Wang Tai-Sen F., Wilde Carl H., Wilke Mark D., Wilson Douglas C., Atkinson Dennis P., Bower Dan E., Drury Owen B., Dzenitis John M., Felker Brian, Fittinghoff David N., Frank Matthias, Liddick Sean N., Moran Michael J., Roberson George P., Weiss Paul, Buckles Robert A., Cradick Jerry R., Kaufman Morris I., Lutz Steve S., Malone Robert M., and Traille Albert

Subjects
Physics, QC1-999
Abstract

Inertial Confinement Fusion experiments at the National Ignition Facility (NIF) are designed to understand and test the basic principles of self-sustaining fusion reactions by laser driven compression of deuterium-tritium (DT) filled cryogenic plastic (CH) capsules. The experimental campaign is ongoing to tune the implosions and characterize the burning plasma conditions. Nuclear diagnostics play an important role in measuring the characteristics of these burning plasmas, providing feedback to improve the implosion dynamics. The Neutron Imaging (NI) diagnostic provides information on the distribution of the central fusion reaction region and the surrounding DT fuel by collecting images at two different energy bands for primary (13–15 MeV) and downscattered (10–12 MeV) neutrons. From these distributions, the final shape and size of the compressed capsule can be estimated and the symmetry of the compression can be inferred. The first downscattered neutron images from imploding ICF capsules are shown in this paper.

Published
2013
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2. Summary of the first neutron image data collected at the National Ignition Facility

Author

Grim Gary P., Archuleta Thomas N., Aragonez Robert J., Atkinson Dennis P., Batha Steven H., Barrios Maria A., Bower Dan E., Bradley David K., Buckles Robert A., Clark David D., Clark Deborah J., Cradick Jerry R., Danly Chris, Drury Owen B., Fatherley Valerie E., Finch Joshua P., Garcia Felix P., Gallegos Robert A., Guler Nevzat, Glenn Steven M., Hsu Albert H., Izumi Nobuhiko, Jaramillo Steven A., Kyrala George A., Pape Sebastien Le, Loomis Eric N., Mares Danielle, Martinson Drew D., Ma Tammy, Mackinnon Andrew J., Merrill Frank E., Morgan George L., Munson Carter, Murphy Thomas J., Polk Paul J., Schmidt Derek W., Tommasini Riccardo, Tregillis Ian L., Valdez Adelaida C., Volegov Petr L., Wang Tai-Sen F., Wilde Carl H., Wilke Mark D., Wilson Douglas C., Dzenitis John M., Felker Brian, Fittinghoff David N., Frank Matthias, Liddick Sean N., Moran Michael J., Roberson George P., Weiss Paul, Kauffman Morris I., Lutz Steve S., Malone Robert M., and Traille Albert

Subjects
Physics, QC1-999
Abstract

A summary of data and results from the first neutron images produced by the National Ignition Facility (NIF), Lawrence Livermore National Laboratory, Livermore, CA, USA are presented. An overview of the neutron imaging technique is presented, as well as a synopsis of data and measurements made to date. Data from directly driven, DT filled microballoons, as well as indirectly driven, cryogenically layered ignition experiments are presented. The data show that the primary cores from directly driven implosions are approximately twice as large, 64 ± 3 μm, as indirectly driven cores, 25 ± 4 and 29 ± 4 μm and more asymmetric, P2/P0 = 47% vs. − 14% and 7%. Further, comparison with the size and shape of X-ray image data on the same implosions show good agreement, indicating X-ray emission is dominated by the hot regions of the implosion.

Published
2013
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3. Crystal Plasticity for Dynamic Loading at High Pressures and Strains

Author

Swift, Damian C., Loomis, Eric N., Peralta, Pedro, and El-Dasher, Bassem

Subjects
Condensed Matter - Materials Science
Abstract

A crystal plasticity theory was developed for use in simulations of dynamic loading at high pressures and strain rates. At pressures of the order of the bulk modulus, compressions o(100%) may be induced. At strain rates o(10^9)/s or higher, elastic strains may reach o(10%), which may change the orientation of the slip systems significantly with respect to the stress field. Elastic strain rather than stress was used in defining the local state, providing a more direct connection with electronic structure predictions and consistency with the treatment of compression in initial value problems in continuum dynamics. Plastic flow was treated through explicit slip systems, with flow on each system taken to occur by thermally-activated random jumps biased by the resolved stress. Compared with simple Arrhenius rates, the biased random jumps caused significant differences in plastic strain rate as a function of temperature and pressure, and provided a seamless transition to the ultimate theoretical strength of the material. The behavior of the theory was investigated for matter with approximate properties for Ta, demonstrating the importance of the high pressure, high strain rate contributions., Comment: Revised per reviewer comments

Published
2007

6. Progress Toward Fabrication of Machined Metal Shells for the First Double-Shell Implosions at the National Ignition Facility

Author

Cardenas, Tana, primary, Schmidt, Derek W., additional, Loomis, Eric N., additional, Randolph, Randall B., additional, Hamilton, Christopher E., additional, Oertel, John, additional, Patterson, Brian M., additional, Henderson, Kevin, additional, Wilson, Doug C., additional, Merritt, Elizabeth, additional, Montgomery, David, additional, Daughton, William, additional, Dodd, Evan, additional, Palaniyappan, Sasikumar, additional, Kline, John, additional, Batha, Steve, additional, Huang, Haibo, additional, Hoppe, Marty L., additional, Schoff, Michael, additional, Rice, Neal, additional, Nikroo, Abbas, additional, Wang, Morris, additional, Seugling, Richard, additional, Bennett, Donald, additional, Johnson, Steve, additional, and Castro, Carlos, additional

Published
2018
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8. Crystal Plasticity for Dynamic Loading at High Pressures and Strains

Author

Swift, Damian C., Loomis, Eric N., Peralta, Pedro, and El-Dasher, Bassem

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

A crystal plasticity theory was developed for use in simulations of dynamic loading at high pressures and strain rates. At pressures of the order of the bulk modulus, compressions o(100%) may be induced. At strain rates o(10^9)/s or higher, elastic strains may reach o(10%), which may change the orientation of the slip systems significantly with respect to the stress field. Elastic strain rather than stress was used in defining the local state, providing a more direct connection with electronic structure predictions and consistency with the treatment of compression in initial value problems in continuum dynamics. Plastic flow was treated through explicit slip systems, with flow on each system taken to occur by thermally-activated random jumps biased by the resolved stress. Compared with simple Arrhenius rates, the biased random jumps caused significant differences in plastic strain rate as a function of temperature and pressure, and provided a seamless transition to the ultimate theoretical strength of the material. The behavior of the theory was investigated for matter with approximate properties for Ta, demonstrating the importance of the high pressure, high strain rate contributions., Comment: Revised per reviewer comments

Published
2008
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9. Fiber-Interferometric Detection of Gun-Launched Projectiles.

Author

Goodwin, Peter M., Marshall, Bruce R., Gustavsen, Richard L., Lang, John M., Pacheco, Adam H., Loomis, Eric N., and Dattelbaum, Dana M.

Subjects
PROJECTILES, BALLISTICS, OPTICAL fibers, INTERFEROMETERS, PLASMA diagnostics
Abstract

We are developing a new diagnostic useful for the non-invasive detection of projectile passage in the launch tube of a gas gun. The sensing element consists of one or more turns of single-mode optical fiber that is epoxy-bonded around the external circumference of the launch tube. The hoop strain induced in the launch tube by the passage of the projectile causes a momentary expansion of the fiber loop. This transient change in path length is detected with high sensitivity using a fiber optic-based interferometer developed by the NSTec Special Technologies Laboratory. We have fielded this new diagnostic, along with fiber optic Bragg grating (FBG) strain gauges we previously used for this purpose, on a variety of gas guns used for shock compression studies at Los Alamos and Sandia National Laboratories.We anticipate that, when coupled with a broad-range analog demodulator circuit, the fiber optic interferometer will have improved dynamic range over that of the FBG strain gauge approach. Moreover, in contrast to the FBG strain gauge which is somewhat temperature sensitive, the interferometric approach requires no alignment immediately prior to the experiment and is therefore easier to implement. Both approaches provide early, pre-event signals useful for triggering high-latency diagnostics. [ABSTRACT FROM AUTHOR]

Published
2017
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