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Your search keyword '"L. J. Atherton"' showing total 5 results
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5 results on '"L. J. Atherton"'

1. Hard X-ray and hot electron environment in vacuum hohlraums at NIF

Author

F. D. Lee, Robert L. Kauffman, David C. Eder, John Foster, D. H. Munro, J. P. Holder, Otto Landen, B. J. MacGowan, Edward I. Moses, S. N. Dixit, John R. Murray, B. K. F. Young, L. J. Atherton, M. J. Shaw, D. E. Hinkel, Paul J. Wegner, R. M. Stevenson, Dan Kalantar, John R. Celeste, R. J. Wallace, Kenneth R. Manes, B. A. Hammel, R. E. Bonanno, Pamela K. Whitman, L. J. Suter, T. G. Parham, Alice Koniges, C. A. Haynam, Marilyn Schneider, B. M. Van Wonterghem, Eduard Dewald, and J. W. McDonald

Subjects
Physics, Astrophysics::High Energy Astrophysical Phenomena, X-ray, General Physics and Astronomy, Plasma, Electron, Fusion power, Laser, law.invention, Hohlraum, law, Plasma diagnostics, Laser power scaling, Atomic physics
Abstract

Time resolved hard x-ray images (hv > 9 keV) and time integrated hard x-ray spectra (hv = 18-150 keV from vacuum hohlraums irradiated with four 351 nm wavelength NIF laser beams are presented as a function of hohlraum size and laser power and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (f hot ) shows correlation with both laser intensity and with an analytic plasma filling model.

Published
2006

2. Shock timing on the National Ignition Facility: First experiments

Author

T. G. Parham, David R. Farley, T. R. Boehly, Kenneth S. Jancaitis, E. L. Dewald, Otto Landen, P. S. Datte, G. Ross, Jon Eggert, Abbas Nikroo, K. N. LaFortune, J. Sater, S. Le Pape, T. N. Malsbury, J. B. Horner, Jeremy Kroll, L. J. Atherton, Harry Robey, S. Azevedo, D. H. Munro, Edward I. Moses, O. S. Jones, Peter M. Celliers, B. J. MacGowan, C. C. Widmayer, A. V. Hamza, G. Frieders, M. J. Shaw, C. F. Walters, Gilbert Collins, K. R. Coffee, Richard Town, M. J. Edwards, Tilo Döppner, M. Bowers, D. Trummer, Cliff Thomas, S. N. Dixit, Daniel S. Clark, Debra Callahan, A. L. Throop, C. A. Haynam, Harry B. Radousky, J. D. Moody, Nathan Meezan, S. M. Pollaine, C. Choate, Suhas Bhandarkar, James E. Fair, R. F. Smith, E. M. Giraldez, P. DiNicola, E T Alger, Carlos E. Castro, Jose Milovich, L. V. Berzins, R. E. Olson, B. K. Young, B. Haid, K. G. Krauter, Marilyn Schneider, John Kline, P. A. Sterne, J. D. Lindl, Daniel H. Kalantar, Evan Mapoles, B. M. Van Wonterghem, C.R. Gibson, E. G. Dzenitis, D. M. Holunga, S. W. Haan, D. D. Meyerhofer, S. J. Brereton, K. A. Moreno, Klaus Widmann, Damien Hicks, and H. Chandrasekaran

Subjects
Physics, business.industry, Nuclear engineering, QC1-999, Shock (mechanics), Pulse (physics), law.invention, Ignition system, Condensed Matter::Soft Condensed Matter, Interferometry, Optics, law, Hohlraum, Physics::Plasma Physics, business, National Ignition Facility
Abstract

An experimental campaign to tune the initial shock compression sequence of capsule implosions on the National Ignition Facility (NIF) was initiated in late 2010. The experiments use a NIF ignition-scale hohlraum and capsule that employs a re-entrant cone to provide optical access to the shocks as they propagate in the liquid deuterium-filled capsule interior. The strength and timing of the shock sequence is diagnosed with velocity interferometry that provides target performance data used to set the pulse shape for ignition capsule implosions that follow. From the start, these measurements yielded significant new information on target performance, leading to improvements in the target design. We describe the results and interpretation of the initial tuning experiments.

Published
2013

3. Shock timing on the National Ignition Facility: The first precision tuning series

Author

L. J. Atherton, Kenneth S. Jancaitis, A. V. Hamza, C. F. Walters, Marilyn Schneider, O. S. Jones, Peter M. Celliers, Suhas Bhandarkar, M. Gatu Johnson, Fredrick Seguin, J. D. Kilkenny, A. J. Mackinnon, Damien Hicks, M. J. Edwards, Tilo Döppner, Brian Spears, D. D. Meyerhofer, C. A. Haynam, M. Bowers, B. Haid, D. T. Casey, B. M. Van Wonterghem, E. L. Dewald, Klaus Widmann, Jose Milovich, S. Le Pape, David R. Farley, D. H. Munro, T. G. Parham, T. R. Boehly, J. P. Knauer, K. N. LaFortune, Edward I. Moses, B. J. MacGowan, S. Azevedo, J. A. Caggiano, Siegfried Glenzer, Otto Landen, E. M. Giraldez, Jon Eggert, Carlos E. Castro, E. G. Dzenitis, Richard Town, E T Alger, J. D. Moody, L. V. Berzins, C. C. Widmayer, Jeremy Kroll, M. J. Shaw, B. Burr, K. R. Coffee, D. M. Holunga, Harry B. Radousky, S. J. Brereton, D. Trummer, S. W. Haan, J. A. Frenje, S. N. Dixit, David C. Clark, H. Chandrasekaran, B. K. Young, K. G. Krauter, John Kline, K. A. Moreno, J. D. Lindl, C. Choate, Abbas Nikroo, T. N. Malsbury, J. B. Horner, and Harry Robey

Subjects
Shock wave, Physics, Series (mathematics), Nuclear engineering, QC1-999, Mechanical engineering, Plasma, Compression (physics), Shock (mechanics), law.invention, Ignition system, law, Physics::Plasma Physics, Area density, Physics::Chemical Physics, National Ignition Facility
Abstract

Ignition implosions on the National Ignition Facility (NIF) [Lindl et al., Phys. Plasmas 11 , 339 (2004)] are driven with a very carefully tailored sequence of four shock waves that must be timed to very high precision in order to keep the fuel on a low adiabat. The first series of precision tuning experiments on NIF have been performed. These experiments use optical diagnostics to directly measure the strength and timing of all four shocks inside the hohlraum-driven, cryogenic deuterium-filled capsule interior. The results of these experiments are presented demonstrating a significant decrease in the fuel adiabat over previously un-tuned implosions. The impact of the improved adiabat on fuel compression is confirmed in related deuterium-tritium (DT) layered capsule implosions by measurement of fuel areal density (ρR), which show the highest fuel compression (ρR ∼ 1.0 g/cm2 ) measured to date.

Published
2013

4. Ignition tuning for the National Ignition Campaign

Author

David R. Farley, L. J. Atherton, A. V. Hamza, N. Meezan, John Kline, O. S. Jones, Peter M. Celliers, Brian Spears, Cliff Thomas, J. Edwards, Abbas Nikroo, Joseph Ralph, Otto Landen, D. K. Bradley, J. D. Kilkenny, J. D. Lindl, K. N. LaFortune, S. M. Glenn, J. D. Moody, R. E. Olson, S. W. Haan, Nelson M. Hoffman, Debra Callahan, C. A. Haynam, A. J. Mackinnon, D. H. Munro, Susan Regan, Jose Milovich, B. J. MacGowan, B. A. Hammel, Siegfried Glenzer, Tilo Doeppner, Richard Town, Jon Eggert, Pierre Michel, E. L. Dewald, Edward I. Moses, George A. Kyrala, Harry Robey, Damien Hicks, S. N. Dixit, T. R. Boehly, N. Izumi, J. A. Frenje, L. J. Suter, and Doug Wilson

Subjects
Engineering, business.industry, Physics, QC1-999, Nuclear engineering, Implosion, Mechanical engineering, Laser, Residual, law.invention, Ignition system, Physics::Plasma Physics, Hohlraum, law, business, Inertial confinement fusion
Abstract

The overall goal of the indirect-drive inertial confinement fusion (1) tuning campaigns (2 )i s to maximize the probability of ignition by experimentally correcting for likely residual uncertainties in the implosion and hohlraum physics (3) used in our radiation-hydrodynamic computational models, and by checking for and resolving unexpected shot-to-shot variability in performance (4). This has been started successfully using a variety of surrogate capsules that set key laser, hohlraum and capsule parameters to maximize ignition capsule implosion velocity, while minimizing fuel adiabat, core shape asymmetry and ablator-fuel mix.

Published
2013

5. Symmetry tuning with megajoule laser pulses at the National Ignition Facility

Author

E. L. Dewald, C. C. Widmayer, Joseph Ralph, P. Di Nicola, Daniel H. Kalantar, Otto Landen, N. Simanovskaia, K. Widmann, John Kline, S. V. Weber, J. D. Moody, S. N. Dixit, O. S. Jones, B. J. MacGowan, N. Izumi, T. G. Parham, R. Benedetti, A. J. Mackinnon, Denise Hinkel, Cliff Thomas, E. J. Bond, Nathan Meezan, L. J. Atherton, Harry B. Radousky, George A. Kyrala, Siegfried Glenzer, Kenneth S. Jancaitis, Robert Heeter, J. D. Kilkenny, Richard Town, Debra Callahan, C. A. Haynam, Tilo Doeppner, Tammy Ma, B Van Wontergheman, E. A. Williams, D. K. Bradley, Marilyn Schneider, S. M. Glenn, M. J. Edwards, L. J. Suter, R. Prasad, K.N. LaFortune, Michael J. Moran, and Pierre Michel

Subjects
Physics, Thermonuclear fusion, business.industry, QC1-999, Implosion, Laser, law.invention, Radiation pattern, Ignition system, Optics, Physics::Plasma Physics, law, Hohlraum, Equivalent weight, National Ignition Facility, business
Abstract

Experiments conducted at the National Ignition Facility using shaped laser pulses with more than 1 MJ of energy have demonstrated the ability to control the implosion symmetry under ignition conditions. To achieve thermonuclear ignition, the low mode asymmetries must be small to minimize the size of the hotspot. The symmetry tuning experiments use symmetry capsules, “symcaps”, which replace the DT fuel with an equivalent mass of CH to emulate the hydrodynamic behavior of an ignition capsule. The x-ray self-emission signature from gas inside the capsule during the peak compression correlates with the surrounding hotspot shape. By tuning the shape of the self-emission, the capsule implosion symmetry can be made to be “round.” In the experimental results presented here, we utilized crossbeam energy transfer [S. H. Glenzer, et al., Science 327, 1228 (2010)] to change the ratio of the inner to outer cone power inside the hohlraum targets on the NIF. Variations in the ratio of the inner cone to outer cone power affect the radiation pattern incident on the capsule modifying the implosion symmetry.

Published
2013

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