Three-dimensional simulations of low foot and high foot implosion experiments on the National Ignition Facility

International Nuclear Information System (INIS)

Clark, D. S.; Weber, C. R.; Milovich, J. L.; Salmonson, J. D.; Kritcher, A. L.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Hurricane, O. A.; Jones, O. S.; Marinak, M. M.; Patel, P. K.; Robey, H. F.; Sepke, S. M.; Edwards, M. J.

2016-01-01

In order to achieve the several hundred Gbar stagnation pressures necessary for inertial confinement fusion ignition, implosion experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] require the compression of deuterium-tritium fuel layers by a convergence ratio as high as forty. Such high convergence implosions are subject to degradation by a range of perturbations, including the growth of small-scale defects due to hydrodynamic instabilities, as well as longer scale modulations due to radiation flux asymmetries in the enclosing hohlraum. Due to the broad range of scales involved, and also the genuinely three-dimensional (3D) character of the flow, accurately modeling NIF implosions remains at the edge of current simulation capabilities. This paper describes the current state of progress of 3D capsule-only simulations of NIF implosions aimed at accurately describing the performance of specific NIF experiments. Current simulations include the effects of hohlraum radiation asymmetries, capsule surface defects, the capsule support tent and fill tube, and use a grid resolution shown to be converged in companion two-dimensional simulations. The results of detailed simulations of low foot implosions from the National Ignition Campaign are contrasted against results for more recent high foot implosions. While the simulations suggest that low foot performance was dominated by ablation front instability growth, especially the defect seeded by the capsule support tent, high foot implosions appear to be dominated by hohlraum flux asymmetries, although the support tent still plays a significant role. For both implosion types, the simulations show reasonable, though not perfect, agreement with the data and suggest that a reliable predictive capability is developing to guide future implosions toward ignition.

Three-dimensional simulations of low foot and high foot implosion experiments on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Clark, D. S.; Weber, C. R.; Milovich, J. L.; Salmonson, J. D.; Kritcher, A. L.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Hurricane, O. A.; Jones, O. S.; Marinak, M. M.; Patel, P. K.; Robey, H. F.; Sepke, S. M.; Edwards, M. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)

2016-05-15

In order to achieve the several hundred Gbar stagnation pressures necessary for inertial confinement fusion ignition, implosion experiments on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] require the compression of deuterium-tritium fuel layers by a convergence ratio as high as forty. Such high convergence implosions are subject to degradation by a range of perturbations, including the growth of small-scale defects due to hydrodynamic instabilities, as well as longer scale modulations due to radiation flux asymmetries in the enclosing hohlraum. Due to the broad range of scales involved, and also the genuinely three-dimensional (3D) character of the flow, accurately modeling NIF implosions remains at the edge of current simulation capabilities. This paper describes the current state of progress of 3D capsule-only simulations of NIF implosions aimed at accurately describing the performance of specific NIF experiments. Current simulations include the effects of hohlraum radiation asymmetries, capsule surface defects, the capsule support tent and fill tube, and use a grid resolution shown to be converged in companion two-dimensional simulations. The results of detailed simulations of low foot implosions from the National Ignition Campaign are contrasted against results for more recent high foot implosions. While the simulations suggest that low foot performance was dominated by ablation front instability growth, especially the defect seeded by the capsule support tent, high foot implosions appear to be dominated by hohlraum flux asymmetries, although the support tent still plays a significant role. For both implosion types, the simulations show reasonable, though not perfect, agreement with the data and suggest that a reliable predictive capability is developing to guide future implosions toward ignition.

The high-foot implosion campaign on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Hurricane, O. A., E-mail: hurricane1@llnl.gov; Callahan, D. A.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Barrios Garcia, M. A.; Hinkel, D. E.; Berzak Hopkins, L. F.; Kervin, P.; Pape, S. Le; Ma, T.; MacPhee, A. G.; Milovich, J. L.; Moody, J.; Pak, A. E.; Patel, P. K.; Park, H.-S.; Remington, B. A.; Robey, H. F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); and others

2014-05-15

The “High-Foot” platform manipulates the laser pulse-shape coming from the National Ignition Facility laser to create an indirect drive 3-shock implosion that is significantly more robust against instability growth involving the ablator and also modestly reduces implosion convergence ratio. This strategy gives up on theoretical high-gain in an inertial confinement fusion implosion in order to obtain better control of the implosion and bring experimental performance in-line with calculated performance, yet keeps the absolute capsule performance relatively high. In this paper, we will cover the various experimental and theoretical motivations for the high-foot drive as well as cover the experimental results that have come out of the high-foot experimental campaign. At the time of this writing, the high-foot implosion has demonstrated record total deuterium-tritium yields (9.3×10{sup 15}) with low levels of inferred mix, excellent agreement with implosion simulations, fuel energy gains exceeding unity, and evidence for the “bootstrapping” associated with alpha-particle self-heating.

Measurements of fuel and ablator ρR in Symmetry-Capsule implosions with the Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Gatu Johnson, M., E-mail: gatu@psfc.mit.edu; Frenje, J. A.; Li, C. K.; Séguin, F. H.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bionta, R. M.; Casey, D. T.; Caggiano, J. A.; Hatarik, R.; Khater, H. Y.; Sayre, D. B. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Knauer, J. P.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Herrmann, H. W. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Kilkenny, J. D. [General Atomics, San Diego, California 92186 (United States)

2014-11-15

The Magnetic Recoil neutron Spectrometer (MRS) on the National Ignition Facility (NIF) measures the neutron spectrum in the energy range of 4–20 MeV. This paper describes MRS measurements of DT-fuel and CH-ablator ρR in DT gas-filled symmetry-capsule implosions at the NIF. DT-fuel ρR's of 80–140 mg/cm{sup 2} and CH-ablator ρR's of 400–680 mg/cm{sup 2} are inferred from MRS data. The measurements were facilitated by an improved correction of neutron-induced background in the low-energy part of the MRS spectrum. This work demonstrates the accurate utilization of the complete MRS-measured neutron spectrum for diagnosing NIF DT implosions.

Impacts of Implosion Asymmetry And Hot Spot Shape On Ignition Capsules

Science.gov (United States)

Cheng, Baolian; Kwan, Thomas J. T.; Wang, Yi-Ming; Yi, S. Austin; Batha, Steve

2017-10-01

Implosion symmetry plays a critical role in achieving high areal density and internal energy at stagnation during hot spot formation in ICF capsules. Asymmetry causes hot spot irregularity and stagnation de-synchronization that results in lower temperatures and areal densities of the hot fuel. These degradations significantly affect the alpha heating process in the DT fuel as well as on the thermonuclear performance of the capsules. In this work, we explore the physical factors determining the shape of the hot spot late in the implosion and the effects of shape on Î+/-particle transport. We extend our ignition theory [1-4] to include the hot spot shape and quantify the effects of the implosion asymmetry on both the ignition criterion and capsule performance. We validate our theory with the NIF existing experimental data Our theory shows that the ignition criterion becomes more restrictive with the deformation of the hot spot. Through comparison with the NIF data, we demonstrate that the shape effects on the capsules' performance become more explicit as the self-heating and yield of the capsules increases. The degradation of the thermonuclear burn by the hot spot shape for high yield shots to date can be as high as 20%. Our theory is in good agreement with the NIF data. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under Contract No. W-7405-ENG-36.

Three-dimensional simulations of Nova capsule implosion experiments

International Nuclear Information System (INIS)

Marinak, M.M.; Tipton, R.E.; Landen, O.L.

1995-01-01

Capsule implosion experiments carried out on the Nova laser are simulated with the three-dimensional HYDRA radiation hydrodynamics code. Simulations of ordered near single mode perturbations indicate that structures which evolve into round spikes can penetrate farthest into the hot spot. Bubble-shaped perturbations can burn through the capsule shell fastest, however, causing even more damage. Simulations of a capsule with multimode perturbations shows spike amplitudes evolving in good agreement with a saturation model during the deceleration phase. The presence of sizable low mode asymmetry, caused either by drive asymmetry or perturbations in the capsule shell, can dramatically affect the manner in which spikes approach the center of the hot spot. Three-dimensional coupling between the low mode shell perturbations intrinsic to Nova capsules and the drive asymmetry brings the simulated yields into closer agreement with the experimental values

Capsule Performance Optimization for the National Ignition Facility

Science.gov (United States)

Landen, Otto

2009-11-01

The overall goal of the capsule performance optimization campaign is to maximize the probability of ignition by experimentally correcting for likely residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. This will be accomplished using a variety of targets that will set key laser, hohlraum and capsule parameters to maximize ignition capsule implosion velocity, while minimizing fuel adiabat, core shape asymmetry and ablator-fuel mix. The targets include high Z re-emission spheres setting foot symmetry through foot cone power balance [1], liquid Deuterium-filled ``keyhole'' targets setting shock speed and timing through the laser power profile [2], symmetry capsules setting peak cone power balance and hohlraum length [3], and streaked x-ray backlit imploding capsules setting ablator thickness [4]. We will show how results from successful tuning technique demonstration shots performed at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design meet the required sensitivity and accuracy. We will also present estimates of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors, and show that these get reduced after a number of shots and iterations to meet an acceptable level of residual uncertainty. Finally, we will present results from upcoming tuning technique validation shots performed at NIF at near full-scale. Prepared by LLNL under Contract DE-AC52-07NA27344. [4pt] [1] E. Dewald, et. al. Rev. Sci. Instrum. 79 (2008) 10E903. [0pt] [2] T.R. Boehly, et. al., Phys. Plasmas 16 (2009) 056302. [0pt] [3] G. Kyrala, et. al., BAPS 53 (2008) 247. [0pt] [4] D. Hicks, et. al., BAPS 53 (2008) 2.

Effects of mode coupling between low-mode radiation flux asymmetry and intermediate-mode ablator roughness on ignition capsule implosions

Directory of Open Access Journals (Sweden)

Jianfa Gu

2017-01-01

Full Text Available The low-mode shell asymmetry and high-mode hot spot mixing appear to be the main reasons for the performance degradation of the National Ignition Facility (NIF implosion experiments. The effects of the mode coupling between low-mode P2 radiation flux asymmetry and intermediate-mode L = 24 capsule roughness on the implosion performance of ignition capsule are investigated by two-dimensional radiation hydrodynamic simulations. It is shown that the amplitudes of new modes generated by the mode coupling are in good agreement with the second-order mode coupling equation during the acceleration phase. The later flow field not only shows large areal density P2 asymmetry in the main fuel, but also generates large-amplitude spikes and bubbles. In the deceleration phase, the increasing mode coupling generates more new modes, and the perturbation spectrum on the hot spot boundary is mainly from the strong mode interactions rather than the initial perturbation conditions. The combination of the low-mode and high-mode perturbations breaks up the capsule shell, resulting in a significant reduction of the hot spot temperature and implosion performance.

Implosion dynamics measurements at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Callahan, D. A.; Doeppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2012-12-15

Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1-1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% {+-} 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%-70%) of its initial radius, reduced the shell thickness and improved the final fuel {rho}R on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell

Implosion dynamics measurements at the National Ignition Facility

International Nuclear Information System (INIS)

Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Callahan, D. A.; Döppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P.

2012-01-01

Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1–1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% ± 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%–70%) of its initial radius, reduced the shell thickness and improved the final fuel ρR on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell

Implosion dynamics measurements at the National Ignition Facility

Science.gov (United States)

Hicks, D. G.; Meezan, N. B.; Dewald, E. L.; Mackinnon, A. J.; Olson, R. E.; Callahan, D. A.; Döppner, T.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Di Nicola, P.; Dixit, S. N.; Dzenitis, E. G.; Eggert, J. E.; Farley, D. R.; Frenje, J. A.; Glenn, S. M.; Glenzer, S. H.; Hamza, A. V.; Heeter, R. F.; Holder, J. P.; Izumi, N.; Kalantar, D. H.; Khan, S. F.; Kline, J. L.; Kroll, J. J.; Kyrala, G. A.; Ma, T.; MacPhee, A. G.; McNaney, J. M.; Moody, J. D.; Moran, M. J.; Nathan, B. R.; Nikroo, A.; Opachich, Y. P.; Petrasso, R. D.; Prasad, R. R.; Ralph, J. E.; Robey, H. F.; Rinderknecht, H. G.; Rygg, J. R.; Salmonson, J. D.; Schneider, M. B.; Simanovskaia, N.; Spears, B. K.; Tommasini, R.; Widmann, K.; Zylstra, A. B.; Collins, G. W.; Landen, O. L.; Kilkenny, J. D.; Hsing, W. W.; MacGowan, B. J.; Atherton, L. J.; Edwards, M. J.

2012-12-01

Measurements have been made of the in-flight dynamics of imploding capsules indirectly driven by laser energies of 1-1.7 MJ at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)]. These experiments were part of the National Ignition Campaign [Landen et al., Phys. Plasmas 18, 051002 (2011)] to iteratively optimize the inputs required to achieve thermonuclear ignition in the laboratory. Using gated or streaked hard x-ray radiography, a suite of ablator performance parameters, including the time-resolved radius, velocity, mass, and thickness, have been determined throughout the acceleration history of surrogate gas-filled implosions. These measurements have been used to establish a dynamically consistent model of the ablative drive history and shell compressibility throughout the implosion trajectory. First results showed that the peak velocity of the original 1.3-MJ Ge-doped polymer (CH) point design using Au hohlraums reached only 75% of the required ignition velocity. Several capsule, hohlraum, and laser pulse changes were then implemented to improve this and other aspects of implosion performance and a dedicated effort was undertaken to test the sensitivity of the ablative drive to the rise time and length of the main laser pulse. Changing to Si rather than Ge-doped inner ablator layers and increasing the pulse length together raised peak velocity to 93% ± 5% of the ignition goal using a 1.5 MJ, 420 TW pulse. Further lengthening the pulse so that the laser remained on until the capsule reached 30% (rather than 60%-70%) of its initial radius, reduced the shell thickness and improved the final fuel ρR on companion shots with a cryogenic hydrogen fuel layer. Improved drive efficiency was observed using U rather than Au hohlraums, which was expected, and by slowing the rise time of laser pulse, which was not. The effect of changing the Si-dopant concentration and distribution, as well as the effect of using a larger initial shell thickness

The effect of laser pulse shape variations on the adiabat of NIF capsule implosions

Energy Technology Data Exchange (ETDEWEB)

Robey, H. F.; MacGowan, B. J.; Landen, O. L.; LaFortune, K. N.; Widmayer, C.; Celliers, P. M.; Moody, J. D.; Ross, J. S.; Ralph, J.; LePape, S.; Berzak Hopkins, L. F.; Spears, B. K.; Haan, S. W.; Clark, D.; Lindl, J. D.; Edwards, M. J. [LLNL, Livermore, California 94550 (United States)

2013-05-15

Indirectly driven capsule implosions on the National Ignition Facility (NIF) [Moses et al., Phys. Plasmas 16, 041006 (2009)] are being performed with the goal of compressing a layer of cryogenic deuterium-tritium (DT) fuel to a sufficiently high areal density (ρR) to sustain the self-propagating burn wave that is required for fusion power gain greater than unity. These implosions are driven with a temporally shaped laser pulse that is carefully tailored to keep the DT fuel on a low adiabat (ratio of fuel pressure to the Fermi degenerate pressure). In this report, the impact of variations in the laser pulse shape (both intentionally and unintentionally imposed) on the in-flight implosion adiabat is examined by comparing the measured shot-to-shot variations in ρR from a large ensemble of DT-layered ignition target implosions on NIF spanning a two-year period. A strong sensitivity to variations in the early-time, low-power foot of the laser pulse is observed. It is shown that very small deviations (∼0.1% of the total pulse energy) in the first 2 ns of the laser pulse can decrease the measured ρR by 50%.

Measurements of an ablator-gas atomic mix in indirectly driven implosions at the National Ignition Facility.

Science.gov (United States)

Smalyuk, V A; Tipton, R E; Pino, J E; Casey, D T; Grim, G P; Remington, B A; Rowley, D P; Weber, S V; Barrios, M; Benedetti, L R; Bleuel, D L; Bradley, D K; Caggiano, J A; Callahan, D A; Cerjan, C J; Clark, D S; Edgell, D H; Edwards, M J; Frenje, J A; Gatu-Johnson, M; Glebov, V Y; Glenn, S; Haan, S W; Hamza, A; Hatarik, R; Hsing, W W; Izumi, N; Khan, S; Kilkenny, J D; Kline, J; Knauer, J; Landen, O L; Ma, T; McNaney, J M; Mintz, M; Moore, A; Nikroo, A; Pak, A; Parham, T; Petrasso, R; Sayre, D B; Schneider, M B; Tommasini, R; Town, R P; Widmann, K; Wilson, D C; Yeamans, C B

2014-01-17

We present the first results from an experimental campaign to measure the atomic ablator-gas mix in the deceleration phase of gas-filled capsule implosions on the National Ignition Facility. Plastic capsules containing CD layers were filled with tritium gas; as the reactants are initially separated, DT fusion yield provides a direct measure of the atomic mix of ablator into the hot spot gas. Capsules were imploded with x rays generated in hohlraums with peak radiation temperatures of ∼294  eV. While the TT fusion reaction probes conditions in the central part (core) of the implosion hot spot, the DT reaction probes a mixed region on the outer part of the hot spot near the ablator-hot-spot interface. Experimental data were used to develop and validate the atomic-mix model used in two-dimensional simulations.

Measuring the implosion symmetry on the NIF laser

International Nuclear Information System (INIS)

Kyrala, G.A.

2010-01-01

Complete text of publication follows. Indirect drive is used to implode capsules in cryogenically cooled hohlraums at the National Ignition Facility. One of the required conditions for successful implosion is spherical symmetry of the imploded capsule at peak compression. Instead of using ignition capsules with frozen D/T fuel, analog capsules called symcaps are used to study the hydrodynamics behavior of the implosion. The symcaps are imploded in hohlraums with the same size, gas fills, and hohlraum gas temperatures of an ignition hohlraums. Symcaps with gaseous fills of deuterium/helium fills are used to emulate the behavior of the ignition capsules. We will describe the technique used to measure the symmetry of the implosion of symcaps, show some of the results of the measurements, how the technique was used to tune the symmetry of the implosion, and briefly discuss the extension of the technique to non-igniting capsules filled with mixtures of T/H/D gases. Acknowledgements. This work was performed by Los Alamos National Laboratory under the auspices of the U. S. Department of Energy under contract No. DE-AC52-06NA25396.

New and improved CH implosions at the National Ignition Facility

Science.gov (United States)

Hinkel, D. E.; Doeppner, T.; Kritcher, A. L.; Ralph, J. E.; Jarrott, L. C.; Albert, F.; Benedetti, L. R.; Field, J. E.; Goyon, C. S.; Hohenberger, M.; Izumi, N.; Milovich, J. L.; Bachmann, B.; Casey, D. T.; Yeamans, C. B.; Callahan, D. A.; Hurricane, O. A.

2017-10-01

Improvements to the hohlraum for CH implosions have resulted in near-record hot spot pressures, 225 Gbar. Implosion symmetry and laser energy coupling are improved by using a hohlraum that, compared to the previous high gas-fill hohlraum, is longer, larger, at lower gas fill density, and is fielded at zero wavelength separation to minimize cross-beam energy transfer. With a capsule at 90% of its original size in this hohlraum, implosion symmetry changes from oblate to prolate, at 33% cone fraction. Simulations highlight improved inner beam propagation as the cause of this symmetry change. These implosions have produced the highest yield for CH ablators at modest power and energy, i.e., 360 TW and 1.4 MJ. Upcoming experiments focus on continued improvement in shape as well as an increase in implosion velocity. Further, results and future plans on an increase in capsule size to improve margin will also be presented. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Reproducibility of hohlraum-driven implosion symmetry on the National Ignition Facility

Directory of Open Access Journals (Sweden)

Kyrala G.A.

2013-11-01

Full Text Available Indirectly driven Symcap capsules are used at the NIF to obtain information about ignition capsule implosion performance, in particular shape. Symcaps replace the cryogenic fuel layer with an equivalent ablator mass and can be similarly diagnosed. Symcaps are good symmetry surrogates to an ignition capsule after the peak of the drive, radiation-hydrodynamics simulations predict that doping of the symcaps vary the behavior of the implosion. We compare the equatorial shapes of a symcap doped with Si or Ge, as well as examine the reproducibility of the shape measurement using two symcaps with the same hohlraum and laser conditions.

Measurement of high-pressure shock waves in cryogenic deuterium-tritium ice layered capsule implosions on NIF.

Science.gov (United States)

Robey, H F; Moody, J D; Celliers, P M; Ross, J S; Ralph, J; Le Pape, S; Berzak Hopkins, L; Parham, T; Sater, J; Mapoles, E R; Holunga, D M; Walters, C F; Haid, B J; Kozioziemski, B J; Dylla-Spears, R J; Krauter, K G; Frieders, G; Ross, G; Bowers, M W; Strozzi, D J; Yoxall, B E; Hamza, A V; Dzenitis, B; Bhandarkar, S D; Young, B; Van Wonterghem, B M; Atherton, L J; Landen, O L; Edwards, M J; Boehly, T R

2013-08-09

The first measurements of multiple, high-pressure shock waves in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility have been performed. The strength and relative timing of these shocks must be adjusted to very high precision in order to keep the DT fuel entropy low and compressibility high. All previous measurements of shock timing in inertial confinement fusion implosions [T. R. Boehly et al., Phys. Rev. Lett. 106, 195005 (2011), H. F. Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] have been performed in surrogate targets, where the solid DT ice shell and central DT gas regions were replaced with a continuous liquid deuterium (D2) fill. This report presents the first experimental validation of the assumptions underlying this surrogate technique.

Three-dimensional modeling of capsule implosions in OMEGA tetrahedral hohlraums

International Nuclear Information System (INIS)

Schnittman, J. D.; Craxton, R. S.

2000-01-01

Tetrahedral hohlraums have been proposed as a means for achieving the highly uniform implosions needed for ignition with inertial confinement fusion (ICF) [J. D. Schnittman and R. S. Craxton, Phys. Plasmas 3, 3786 (1996)]. Recent experiments on the OMEGA laser system have achieved good drive uniformity consistent with theoretical predictions [J. M. Wallace et al., Phys. Rev. Lett. 82, 3807 (1999)]. To better understand these experiments and future investigations of high-convergence ICF implosions, the three-dimensional (3-D) view-factor code BUTTERCUP has been expanded to model the time-dependent radiation transport in the hohlraum and the hydrodynamic implosion of the capsule. Additionally, a 3-D postprocessor has been written to simulate x-ray images of the imploded core. Despite BUTTERCUP's relative simplicity, its predictions for radiation drive temperatures, fusion yields, and core deformation show close agreement with experiment. (c) 2000 American Institute of Physics

Indirectly driven, high convergence inertial confinement fusion implosions

International Nuclear Information System (INIS)

Cable, M.D.; Hatchett, S.P.; Caird, J.A.; Kilkenny, J.D.; Kornblum, H.N.; Lane, S.M.; Laumann, C.; Lerche, R.A.; Murphy, T.J.; Murray, J.; Nelson, M.B.; Phillion, D.W.; Powell, H.; Ress, D.B.

1994-01-01

A series of high convergence indirectly driven implosions has been done with the Nova Laser Fusion facility. These implosions were well characterized by a variety of measurements; computer models are in good agreement. The imploded fuel areal density was measured using a technique based on secondary neutron spectroscopy. At capsule convergences of 24:1, comparable to what is required for the hot spot of ignition scale capsules, these capsules achieved fuel densities of 19 g/cm 3 . Independent measurements of density, burn duration, and ion temperature gave nτθ=1.7±0.9x10 14 keV s/cm 3

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

Energy Technology Data Exchange (ETDEWEB)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Hohenberger, M.; Boehly, T. R. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States); Nikroo, A. [General Atomics, San Diego, California 92196 (United States)

2014-02-15

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2014-02-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing.

Shock timing measurements and analysis in deuterium-tritium-ice layered capsule implosions on NIF

International Nuclear Information System (INIS)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Landen, O. L.; Edwards, M. J.; Hohenberger, M.; Boehly, T. R.; Nikroo, A.

2014-01-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion implosions [Boehly et al., Phys. Rev. Lett. 106, 195005 (2011); Robey et al., Phys. Rev. Lett. 108, 215004 (2012)] were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. Comparison of the data with simulation shows good agreement for the timing of the first three shocks, but reveals a considerable discrepancy in the timing of the 4th shock in DT ice layered implosions. Electron preheat is examined as a potential cause of the observed discrepancy in the 4th shock timing

First results of radiation-driven, layered deuterium-tritium implosions with a 3-shock adiabat-shaped drive at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Smalyuk, V. A.; Robey, H. F.; Döppner, T.; Jones, O. S.; Milovich, J. L.; Bachmann, B.; Baker, K. L.; Berzak Hopkins, L. F.; Bond, E.; Callahan, D. A.; Casey, D. T.; Celliers, P. M.; Cerjan, C.; Clark, D. S.; Dixit, S. N.; Edwards, M. J.; Haan, S. W.; Hamza, A. V.; Hurricane, O. A.; Jancaitis, K. S. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2015-08-15

Radiation-driven, layered deuterium-tritium plastic capsule implosions were carried out using a new, 3-shock “adiabat-shaped” drive on the National Ignition Facility. The purpose of adiabat shaping is to use a stronger first shock, reducing hydrodynamic instability growth in the ablator. The shock can decay before reaching the deuterium-tritium fuel leaving it on a low adiabat and allowing higher fuel compression. The fuel areal density was improved by ∼25% with this new drive compared to similar “high-foot” implosions, while neutron yield was improved by more than 4 times, compared to “low-foot” implosions driven at the same compression and implosion velocity.

Hohlraum-driven mid-Z (SiO2) double-shell implosions on the omega laser facility and their scaling to NIF.

Science.gov (United States)

Robey, H F; Amendt, P A; Milovich, J L; Park, H-S; Hamza, A V; Bono, M J

2009-10-02

High-convergence, hohlraum-driven implosions of double-shell capsules using mid-Z (SiO2) inner shells have been performed on the OMEGA laser facility [T. R. Boehly, Opt. Commun. 133, 495 (1997)]. These experiments provide an essential extension of the results of previous low-Z (CH) double-shell implosions [P. A. Amendt, Phys. Rev. Lett. 94, 065004 (2005)] to materials of higher density and atomic number. Analytic modeling, supported by highly resolved 2D numerical simulations, is used to account for the yield degradation due to interfacial atomic mixing. This extended experimental database from OMEGA enables a validation of the mix model, and provides a means for quantitatively assessing the prospects for high-Z double-shell implosions on the National Ignition Facility [Paisner, Laser Focus World 30, 75 (1994)].

New tuning method of the low-mode asymmetry for ignition capsule implosions

International Nuclear Information System (INIS)

Gu, Jianfa; Dai, Zhensheng; Zou, Shiyang; Song, Peng; Ye, Wenhua; Zheng, Wudi; Gu, Peijun

2015-01-01

In the deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility, the hot spot and the surrounding main fuel layer show obvious P2 asymmetries. This may be caused by the large positive P2 radiation flux asymmetry during the peak pulse resulting form the poor propagation of the inner laser beam in the gas-filled hohlraum. The symmetry evolution of ignition capsule implosions is investigated by applying P2 radiation flux asymmetries during different time intervals. A series of two-dimensional simulation results show that a positive P2 flux asymmetry during the peak pulse results in a positive P2 shell ρR asymmetry; while an early time positive P2 flux asymmetry causes a negative P2 in the fuel ρR shape. The opposite evolution behavior of shell ρR asymmetry is used to develop a new tuning method to correct the radiation flux asymmetry during the peak pulse by adding a compensating same-phased P2 drive asymmetry during the early time. The significant improvements of the shell ρR symmetry, hot spot shape, hot spot internal energy, and neutron yield indicate that the tuning method is quite effective. The similar tuning method can also be used to control the early time drive asymmetries

Use of d-3He proton spectroscopy as a diagnostic of shell rho r in capsule implosion experiments with approximately 0.2 NIF scale high temperature Hohlraums at Omega.

Science.gov (United States)

Delamater, N D; Wilson, D C; Kyrala, G A; Seifter, A; Hoffman, N M; Dodd, E; Singleton, R; Glebov, V; Stoeckl, C; Li, C K; Petrasso, R; Frenje, J

2008-10-01

We present the calculations and preliminary results from experiments on the Omega laser facility using d-(3)He filled plastic capsule implosions in gold Hohlraums. These experiments aim to develop a technique to measure shell rho r and capsule unablated mass with proton spectroscopy and will be applied to future National Ignition Facility (NIF) experiments with ignition scale capsules. The Omega Hohlraums are 1900 microm length x 1200 microm diameter and have a 70% laser entrance hole. This is approximately a 0.2 NIF scale ignition Hohlraum and reaches temperatures of 265-275 eV similar to those during the peak of the NIF drive. These capsules can be used as a diagnostic of shell rho r, since the d-(3)He gas fill produces 14.7 MeV protons in the implosion, which escape through the shell and produce a proton spectrum that depends on the integrated rho r of the remaining shell mass. The neutron yield, proton yield, and spectra change with capsule shell thickness as the unablated mass or remaining capsule rho r changes. Proton stopping models are used to infer shell unablated mass and shell rho r from the proton spectra measured with different filter thicknesses. The experiment is well modeled with respect to Hohlraum energetics, neutron yields, and x-ray imploded core image size, but there are discrepancies between the observed and simulated proton spectra.

Dynamic symmetry of indirectly driven inertial confinement fusion capsules on the National Ignition Facility

International Nuclear Information System (INIS)

Town, R. P. J.; Bradley, D. K.; Kritcher, A.; Jones, O. S.; Rygg, J. R.; Tommasini, R.; Barrios, M.; Benedetti, L. R.; Berzak Hopkins, L. F.; Celliers, P. M.; Döppner, T.; Dewald, E. L.; Eder, D. C.; Field, J. E.; Glenn, S. M.; Izumi, N.; Haan, S. W.; Khan, S. F.; Ma, T.; Milovich, J. L.

2014-01-01

In order to achieve ignition using inertial confinement fusion it is important to control the growth of low-mode asymmetries as the capsule is compressed. Understanding the time-dependent evolution of the shape of the hot spot and surrounding fuel layer is crucial to optimizing implosion performance. A design and experimental campaign to examine sources of asymmetry and to quantify symmetry throughout the implosion has been developed and executed on the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)]. We have constructed a large simulation database of asymmetries applied during different time intervals. Analysis of the database has shown the need to measure and control the hot-spot shape, areal density distribution, and symmetry swings during the implosion. The shape of the hot spot during final stagnation is measured using time-resolved imaging of the self-emission, and information on the shape of the fuel at stagnation can be obtained from Compton radiography [R. Tommasini et al., Phys. Plasmas 18, 056309 (2011)]. For the first time on NIF, two-dimensional inflight radiographs of gas-filled and cryogenic fuel layered capsules have been measured to infer the symmetry of the radiation drive on the capsule. These results have been used to modify the hohlraum geometry and the wavelength tuning to improve the inflight implosion symmetry. We have also expanded our shock timing capabilities by the addition of extra mirrors inside the re-entrant cone to allow the simultaneous measurement of shock symmetry in three locations on a single shot, providing asymmetry information up to Legendre mode 4. By diagnosing the shape at nearly every step of the implosion, we estimate that shape has typically reduced fusion yield by about 50% in ignition experiments

Thin shell, high velocity inertial confinement fusion implosions on the national ignition facility.

Science.gov (United States)

Ma, T; Hurricane, O A; Callahan, D A; Barrios, M A; Casey, D T; Dewald, E L; Dittrich, T R; Döppner, T; Haan, S W; Hinkel, D E; Berzak Hopkins, L F; Le Pape, S; MacPhee, A G; Pak, A; Park, H-S; Patel, P K; Remington, B A; Robey, H F; Salmonson, J D; Springer, P T; Tommasini, R; Benedetti, L R; Bionta, R; Bond, E; Bradley, D K; Caggiano, J; Celliers, P; Cerjan, C J; Church, J A; Dixit, S; Dylla-Spears, R; Edgell, D; Edwards, M J; Field, J; Fittinghoff, D N; Frenje, J A; Gatu Johnson, M; Grim, G; Guler, N; Hatarik, R; Herrmann, H W; Hsing, W W; Izumi, N; Jones, O S; Khan, S F; Kilkenny, J D; Knauer, J; Kohut, T; Kozioziemski, B; Kritcher, A; Kyrala, G; Landen, O L; MacGowan, B J; Mackinnon, A J; Meezan, N B; Merrill, F E; Moody, J D; Nagel, S R; Nikroo, A; Parham, T; Ralph, J E; Rosen, M D; Rygg, J R; Sater, J; Sayre, D; Schneider, M B; Shaughnessy, D; Spears, B K; Town, R P J; Volegov, P L; Wan, A; Widmann, K; Wilde, C H; Yeamans, C

2015-04-10

Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165  μm in thickness, 10% and 15% thinner, respectively, than the nominal thickness capsule used throughout the high foot and most of the National Ignition Campaign. These three-shock, high-adiabat, high-foot implosions have demonstrated good performance, with higher velocity and better symmetry control at lower laser powers and energies than their nominal thickness ablator counterparts. Little to no hydrodynamic mix into the DT hot spot has been observed despite the higher velocities and reduced depth for possible instability feedthrough. Early results have shown good repeatability, with up to 1/2 the neutron yield coming from α-particle self-heating.

Diagnosing radiative shocks from deuterium and tritium implosions on NIF.

Science.gov (United States)

Pak, A; Divol, L; Weber, S; Döppner, T; Kyrala, G A; Kilne, J; Izumi, N; Glenn, S; Ma, T; Town, R P; Bradley, D K; Glenzer, S H

2012-10-01

During the recent ignition tuning campaign at the National Ignition Facility, layered cryogenic deuterium and tritium capsules were imploded via x-ray driven ablation. The hardened gated x-ray imager diagnostic temporally and spatially resolves the x-ray emission from the core of the capsule implosion at energies above ~8 keV. On multiple implosions, ~200-400 ps after peak compression a spherically expanding radiative shock has been observed. This paper describes the methods used to characterize the radial profile and rate of expansion of the shock induced x-ray emission.

The effects of convergence ratio on the implosion behavior of DT layered inertial confinement fusion capsules

Science.gov (United States)

Haines, Brian M.; Yi, S. A.; Olson, R. E.; Khan, S. F.; Kyrala, G. A.; Zylstra, A. B.; Bradley, P. A.; Peterson, R. R.; Kline, J. L.; Leeper, R. J.; Shah, R. C.

2017-07-01

The wetted foam capsule design for inertial confinement fusion capsules, which includes a foam layer wetted with deuterium-tritium liquid, enables layered capsule implosions with a wide range of hot-spot convergence ratios (CR) on the National Ignition Facility. We present a full-scale wetted foam capsule design that demonstrates high gain in one-dimensional simulations. In these simulations, increasing the convergence ratio leads to an improved capsule yield due to higher hot-spot temperatures and increased fuel areal density. High-resolution two-dimensional simulations of this design are presented with detailed and well resolved models for the capsule fill tube, support tent, surface roughness, and predicted asymmetries in the x-ray drive. Our modeling of these asymmetries is validated by comparisons with available experimental data. In 2D simulations of the full-scale wetted foam capsule design, jetting caused by the fill tube is prevented by the expansion of the tungsten-doped shell layer due to preheat. While the impacts of surface roughness and predicted asymmetries in the x-ray drive are enhanced by convergence effects, likely underpredicted in 2D at high CR, simulations predict that the capsule is robust to these features. Nevertheless, the design is highly susceptible to the effects of the capsule support tent, which negates all of the one-dimensional benefits of increasing the convergence ratio. Indeed, when the support tent is included in simulations, the yield decreases as the convergence ratio is increased for CR > 20. Nevertheless, the results suggest that the full-scale wetted foam design has the potential to outperform ice layer capsules given currently achievable levels of asymmetries when fielded at low convergence ratios (CR < 20).

Assessment of the impact that the capsule fill tube has on implosions conducted with high density carbon ablators

Science.gov (United States)

Pak, Arthur; Benedetti, L. R.; Berzak Hopkins, L. F.; Clark, D.; Divol, L.; Dewald, E. L.; Fittinghoff, D.; Izumi, N.; Khan, S. F.; Landen, O.; Lepape, S.; Ma, T.; Marley, E.; Nagel, S.; Volegov, P.; Weber, C.; Bradley, D. K.; Callahan, D.; Grim, G.; Hurricane, O. A.; Patel, P.; Schneider, M. B.; Edwards, M. J.

2017-10-01

In recent inertial confinement implosion experiments conducted at the National Ignition Facility, bright and spatially localized x-ray emission within the hot spot at stagnation has been observed. This emission is associated with higher Z ablator material that is injected into the hot spot by the hydrodynamic perturbation induced by the 5-10 um diameter capsule fill tube. The reactivity of the DT fuel and subsequent yield of the implosion are strongly dependent on the density, temperature, and confinement time achieved throughout the stagnation of the implosion. Radiative losses from higher Z ablator material that mixes into the hot spot as well as non-uniformities in the compression and confinement induced by the fill tube perturbation can degrade the yield of the implosion. This work will examine the impact to conditions at stagnation that results from the fill tube perturbation. This assessment will be based from a pair of experiments conducted with a high density carbon ablator where the only deliberate change was reduction in fill tube diameter from 10 to 5 um. An estimate of the radiative losses and impact on performance from ablator mix injected into the hot spot by the fill tube perturbation will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Capsule Performance Optimization in the National Ignition Campaign

Energy Technology Data Exchange (ETDEWEB)

Landen, O L; MacGowan, B J; Haan, S W; Edwards, J

2009-10-13

A capsule performance optimization campaign will be conducted at the National Ignition Facility to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Capsule performance optimization in the national ignition campaign

International Nuclear Information System (INIS)

Landen, O L; MacGowan, B J; Haan, S W; Edwards, J

2010-01-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [1] to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Capsule performance optimization in the national ignition campaign

Science.gov (United States)

Landen, O. L.; MacGowan, B. J.; Haan, S. W.; Edwards, J.

2010-08-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [1] to substantially increase the probability of ignition. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the Omega facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Performance of high-density-carbon (HDC) ablator implosion experiments on the National Ignition Facility (NIF)

Science.gov (United States)

MacKinnon, Andy

2013-10-01

A series of experiments on the National Ignition Facility (NIF) have been performed to measure high-density carbon (HDC) ablator performance for indirect drive inertial confinement fusion (ICF). HDC is a very promising ablator material; being 3x denser than plastic, it absorbs more hohlraum x-rays, leading to higher implosion efficiency. For the HDC experiments the NIF laser generated shaped laser pulses with peak power up to 410 TW and total energy of 1.3 MJ. Pulse shapes were designed to drive 2, 3 or 4 shocks in cryogenic layered implosions. The 2-shock pulse, with a designed fuel adiabat of ~3 is 6-7ns in duration, allowing use of near vacuum hohlraums, which greatly increases the coupling efficiency due to low backscatter losses. Excellent results were obtained for 2,3 and 4 shock pulses. In particular a deuterium-tritium gas filled HDC capsule driven by a 4-shock pulse in a gas-filled hohlraum produced a neutron yield of 1.6 × 1015, a record for a non-cryogenically layered capsule driven by a gas-filled hohlraum. The first 2-shock experiment used a vacuum hohlraum to drive a DD gas filled HDC capsule with a 6.5 ns, laser pulse. This hohlraum was 40% more efficient than the gas-filled counterpart used for 3 and 4 shock experiments, producing near 1D performance at 11 x convergence ratio, peak radiation temperature of 317 eV, 98% laser-hohlraum coupling, and DD neutron yield of 2.2e13, a record for a laser driven DD implosion. The HDC campaigns will be presented, including options for pushing towards the alpha dominated regime. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Recent results from the first polar direct drive plastic capsule implosions on NIF

Science.gov (United States)

Schmitt, Mark J.

2012-10-01

Polar direct drive (PDD) offers a simplified platform for conducting strongly driven implosions on NIF to investigate mix, hydro-burn and ignition-relevant physics. Its successful use necessitates a firm understanding and predictive capability of its implosion characteristics including hydro performance, symmetry and yield. To assess this capability, the first two PDD implosions of deuterium filled CH capsules were recently conducted at NIF. The P2 Legendre mode symmetry seen in these implosions agreed with pre-shot predictions even though the 700kJ drive energy produced intensities that far exceeded thresholds for both Raman and Brillouin stimulated scattering. These shots were also the first to employ image backlighting driven by two laser quads. Preliminary results indicate that the yield from the uncoated 2.25 mm diameter, 42 μm thick, CH shells was reduced by about a factor of two owing to as-shot laser drive asymmetries. Similarly, a small (sim50 μm) centroid offset between the upper and lower shell hemispheres seen in the first shot appears to be indicative of the laser quad energies. Overall, the implosion trajectories agreed with pre-shot predictions of bangtime. The second shot incorporated an 80 ?m wide,10 ?m deep depression encircling the equator of the capsule. This engineered feature was imposed to test our capability to predict the effect of high-mode features on yield and mix. A predicted yield reduction factor of 3 was not observed.[4pt] In collaboration with P. A. Bradley, J. A. Cobble, P. Hakel, S. C. Hsu, N. S. Krasheninnikova, G. A. Kyrala, G. R. Magelssen, T. J. Murphy, K. A. Obrey, R. C. Shah, I. L. Tregillis and F. J. Wysocki of Los Alamos National Laboratory; M. Marinak, R. Wallace, T. Parham, M. Cowan, S. Glenn, R. Benedetti and the NIF Operations Team of Lawrence Livermore National Laboratory; R. S. Craxton and P. W. McKenty of the Univ. Rochester; P. Fitzsimmons and A. Nikroo of General Atomics; H. Rinderknecht, M. Rosenberg, and M. G

Progress in detailed modelling of low foot and high foot implosion experiments on the National Ignition Facility

Science.gov (United States)

Clark, D. S.; Weber, C. R.; Eder, D. C.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Jones, O. S.; Kritcher, A. L.; Marinak, M. M.; Milovich, J. L.; Patel, P. K.; Robey, H. F.; Salmonson, J. D.; Sepke, S. M.

2016-05-01

Several dozen high convergence inertial confinement fusion ignition experiments have now been completed on the National Ignition Facility (NIF). These include both “low foot” experiments from the National Ignition Campaign (NIC) and more recent “high foot” experiments. At the time of the NIC, there were large discrepancies between simulated implosion performance and experimental data. In particular, simulations over predicted neutron yields by up to an order of magnitude, and some experiments showed clear evidence of mixing of ablator material deep into the hot spot that could not be explained at the time. While the agreement between data and simulation improved for high foot implosion experiments, discrepancies nevertheless remain. This paper describes the state of detailed modelling of both low foot and high foot implosions using 1-D, 2-D, and 3-D radiation hydrodynamics simulations with HYDRA. The simulations include a range of effects, in particular, the impact of the plastic membrane used to support the capsule in the hohlraum, as well as low-mode radiation asymmetries tuned to match radiography measurements. The same simulation methodology is applied to low foot NIC implosion experiments and high foot implosions, and shows a qualitatively similar level of agreement for both types of implosions. While comparison with the experimental data remains imperfect, a reasonable level of agreement is emerging and shows a growing understanding of the high-convergence implosions being performed on NIF.

Progress in detailed modelling of low foot and high foot implosion experiments on the National Ignition Facility

International Nuclear Information System (INIS)

Clark, D S; Weber, C R; Eder, D C; Haan, S W; Hammel, B A; Hinkel, D E; Jones, O S; Kritcher, A L; Marinak, M M; Milovich, J L; Patel, P K; Robey, H F; Salmonson, J D; Sepke, S M

2016-01-01

Several dozen high convergence inertial confinement fusion ignition experiments have now been completed on the National Ignition Facility (NIF). These include both “low foot” experiments from the National Ignition Campaign (NIC) and more recent “high foot” experiments. At the time of the NIC, there were large discrepancies between simulated implosion performance and experimental data. In particular, simulations over predicted neutron yields by up to an order of magnitude, and some experiments showed clear evidence of mixing of ablator material deep into the hot spot that could not be explained at the time. While the agreement between data and simulation improved for high foot implosion experiments, discrepancies nevertheless remain. This paper describes the state of detailed modelling of both low foot and high foot implosions using 1-D, 2-D, and 3-D radiation hydrodynamics simulations with HYDRA. The simulations include a range of effects, in particular, the impact of the plastic membrane used to support the capsule in the hohlraum, as well as low-mode radiation asymmetries tuned to match radiography measurements. The same simulation methodology is applied to low foot NIC implosion experiments and high foot implosions, and shows a qualitatively similar level of agreement for both types of implosions. While comparison with the experimental data remains imperfect, a reasonable level of agreement is emerging and shows a growing understanding of the high-convergence implosions being performed on NIF. (paper)

Imaging of High-Z doped, Imploded Capsule Cores

Science.gov (United States)

Prisbrey, Shon T.; Edwards, M. John; Suter, Larry J.

2006-10-01

The ability to correctly ascertain the shape of imploded fusion capsules is critical to be able to achieve the spherical symmetry needed to maximize the energy yield of proposed fusion experiments for the National Ignition Facility. Implosion of the capsule creates a hot, dense core. The introduction of a high-Z dopant into the gas-filled core of the capsule increases the amount of bremsstrahlung radiation produced in the core and should make the imaging of the imploded core easier. Images of the imploded core can then be analyzed to ascertain the symmetry of the implosion. We calculate that the addition of Ne gas into a deuterium gas core will increase the amount of radiation emission while preserving the surrogacy of the radiation and hydrodynamics in the indirect drive NIF hohlraum in the proposed cryogenic hohlraums. The increased emission will more easily enable measurement of asymmetries and tuning of the implosion.

Designing cylindrical implosion experiments on NIF to study deceleration phase of Rayleigh-Taylor

Science.gov (United States)

Vazirani, N.; Kline, J. L.; Loomis, E.; Sauppe, J. P.; Palaniyappan, S.; Flippo, K.; Srinivasan, B.; Malka, E.; Bose, A.; Shvarts, D.

2017-10-01

The Rayleigh-Taylor (RT) hydrodynamic instability occurs when a lower density fluid pushes on a higher density fluid. This occurs in inertial confinement fusion (ICF) implosions at each of the capsule interfaces during the initial acceleration and the deceleration as it stagnates. The RT instabilities mix capsule material into the fusion fuel degrading the Deuterium-Tritium reactivity and ultimately play a key role in limiting target performance. While significant effort has focused on understanding RT at the outer capsule surface, little work has gone into understanding the inner surface RT instability growth during the deceleration phase. Direct measurements of the RT instability are difficult to make at high convergence in a spherical implosion. Here we present the design of a cylindrical implosion system for the National Ignition Facility for studying deceleration phase RT. We will discuss the experimental design, the estimated instability growth, and our outstanding concerns.

Capsule performance optimization in the National Ignition Campaigna)

Science.gov (United States)

Landen, O. L.; Boehly, T. R.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Glenzer, S. H.; Hamza, A.; Hicks, D. G.; Hoffman, N.; Izumi, N.; Jones, O. S.; Kirkwood, R. K.; Kyrala, G. A.; Michel, P.; Milovich, J.; Munro, D. H.; Nikroo, A.; Olson, R. E.; Robey, H. F.; Spears, B. K.; Thomas, C. A.; Weber, S. V.; Wilson, D. C.; Marinak, M. M.; Suter, L. J.; Hammel, B. A.; Meyerhofer, D. D.; Atherton, J.; Edwards, J.; Haan, S. W.; Lindl, J. D.; MacGowan, B. J.; Moses, E. I.

2010-05-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Capsule performance optimization in the National Ignition Campaign

International Nuclear Information System (INIS)

Landen, O. L.; Bradley, D. K.; Braun, D. G.; Callahan, D. A.; Celliers, P. M.; Collins, G. W.; Dewald, E. L.; Divol, L.; Glenzer, S. H.; Hamza, A.; Hicks, D. G.; Izumi, N.; Jones, O. S.; Kirkwood, R. K.; Michel, P.; Milovich, J.; Munro, D. H.; Robey, H. F.; Spears, B. K.; Thomas, C. A.

2010-01-01

A capsule performance optimization campaign will be conducted at the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, 228 (2004)] to substantially increase the probability of ignition by laser-driven hohlraums [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)]. The campaign will experimentally correct for residual uncertainties in the implosion and hohlraum physics used in our radiation-hydrodynamic computational models before proceeding to cryogenic-layered implosions and ignition attempts. The required tuning techniques using a variety of ignition capsule surrogates have been demonstrated at the OMEGA facility under scaled hohlraum and capsule conditions relevant to the ignition design and shown to meet the required sensitivity and accuracy. In addition, a roll-up of all expected random and systematic uncertainties in setting the key ignition laser and target parameters due to residual measurement, calibration, cross-coupling, surrogacy, and scale-up errors has been derived that meets the required budget.

Analysis of NIF experiments with the minimal energy implosion model

Energy Technology Data Exchange (ETDEWEB)

Cheng, B., E-mail: bcheng@lanl.gov; Kwan, T. J. T.; Wang, Y. M.; Merrill, F. E.; Batha, S. H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Cerjan, C. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2015-08-15

We apply a recently developed analytical model of implosion and thermonuclear burn to fusion capsule experiments performed at the National Ignition Facility that used low-foot and high-foot laser pulse formats. Our theoretical predictions are consistent with the experimental data. Our studies, together with neutron image analysis, reveal that the adiabats of the cold fuel in both low-foot and high-foot experiments are similar. That is, the cold deuterium-tritium shells in those experiments are all in a high adiabat state at the time of peak implosion velocity. The major difference between low-foot and high-foot capsule experiments is the growth of the shock-induced instabilities developed at the material interfaces which lead to fuel mixing with ablator material. Furthermore, we have compared the NIF capsules performance with the ignition criteria and analyzed the alpha particle heating in the NIF experiments. Our analysis shows that alpha heating was appreciable only in the high-foot experiments.

Analysis of NIF experiments with the minimal energy implosion model

International Nuclear Information System (INIS)

Cheng, B.; Kwan, T. J. T.; Wang, Y. M.; Merrill, F. E.; Batha, S. H.; Cerjan, C. J.

2015-01-01

We apply a recently developed analytical model of implosion and thermonuclear burn to fusion capsule experiments performed at the National Ignition Facility that used low-foot and high-foot laser pulse formats. Our theoretical predictions are consistent with the experimental data. Our studies, together with neutron image analysis, reveal that the adiabats of the cold fuel in both low-foot and high-foot experiments are similar. That is, the cold deuterium-tritium shells in those experiments are all in a high adiabat state at the time of peak implosion velocity. The major difference between low-foot and high-foot capsule experiments is the growth of the shock-induced instabilities developed at the material interfaces which lead to fuel mixing with ablator material. Furthermore, we have compared the NIF capsules performance with the ignition criteria and analyzed the alpha particle heating in the NIF experiments. Our analysis shows that alpha heating was appreciable only in the high-foot experiments

High-adiabat high-foot inertial confinement fusion implosion experiments on the national ignition facility.

Science.gov (United States)

Park, H-S; Hurricane, O A; Callahan, D A; Casey, D T; Dewald, E L; Dittrich, T R; Döppner, T; Hinkel, D E; Berzak Hopkins, L F; Le Pape, S; Ma, T; Patel, P K; Remington, B A; Robey, H F; Salmonson, J D; Kline, J L

2014-02-07

This Letter reports on a series of high-adiabat implosions of cryogenic layered deuterium-tritium (DT) capsules indirectly driven by a "high-foot" laser drive pulse at the National Ignition Facility. High-foot implosions have high ablation velocities and large density gradient scale lengths and are more resistant to ablation-front Rayleigh-Taylor instability induced mixing of ablator material into the DT hot spot. Indeed, the observed hot spot mix in these implosions was low and the measured neutron yields were typically 50% (or higher) of the yields predicted by simulation. On one high performing shot (N130812), 1.7 MJ of laser energy at a peak power of 350 TW was used to obtain a peak hohlraum radiation temperature of ∼300  eV. The resulting experimental neutron yield was (2.4±0.05)×10(15) DT, the fuel ρR was (0.86±0.063)  g/cm2, and the measured Tion was (4.2±0.16)  keV, corresponding to 8 kJ of fusion yield, with ∼1/3 of the yield caused by self-heating of the fuel by α particles emitted in the initial reactions. The generalized Lawson criteria, an ignition metric, was 0.43 and the neutron yield was ∼70% of the value predicted by simulations that include α-particle self-heating.

The I-Raum: A new shaped hohlraum for improved inner beam propagation in indirectly-driven ICF implosions on the National Ignition Facility

Science.gov (United States)

Robey, H. F.; Berzak Hopkins, L.; Milovich, J. L.; Meezan, N. B.

2018-01-01

Recent work in indirectly-driven inertial confinement fusion implosions on the National Ignition Facility has indicated that late-time propagation of the inner cones of laser beams (23° and 30°) is impeded by the growth of a "bubble" of hohlraum wall material (Au or depleted uranium), which is initiated by and is located at the location where the higher-intensity outer beams (44° and 50°) hit the hohlraum wall. The absorption of the inner cone beams by this "bubble" reduces the laser energy reaching the hohlraum equator at late time driving an oblate or pancaked implosion, which limits implosion performance. In this article, we present the design of a new shaped hohlraum designed specifically to reduce the impact of this bubble by adding a recessed pocket at the location where the outer cones hit the hohlraum wall. This recessed pocket displaces the bubble radially outward, reducing the inward penetration of the bubble at all times throughout the implosion and increasing the time for inner beam propagation by approximately 1 ns. This increased laser propagation time allows one to drive a larger capsule, which absorbs more energy and is predicted to improve implosion performance. The new design is based on a recent National Ignition Facility shot, N170601, which produced a record neutron yield. The expansion rate and absorption of laser energy by the bubble is quantified for both cylindrical and shaped hohlraums, and the predicted performance is compared.

Radiation symmetry control for inertial confinement fusion capsule implosions in double Z-pinch hohlraums on Z

International Nuclear Information System (INIS)

Vesey, Roger A.; Cuneo, Michael E.; Porter, John L. Jr.; Adams, Richard G.; Aragon, Rafael A.; Rambo, Patrick K.; Ruggles, Laurence E.; Simpson, Walter W.; Smith, Ian C.; Bennett, Guy R.

2003-01-01

The double Z-pinch hohlraum high-yield concept [Hammer et al., Phys. Plasmas 6, 2129 (1999)] utilizes two 63-MA Z pinches to heat separate primary hohlraums at either end of a secondary hohlraum containing the cryogenic fusion capsule. Recent experiments on the Z accelerator [Spielman et al., Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories have developed an advanced single-sided power feed, double Z-pinch load to study radiation symmetry and pinch power balance using implosion capsules [Cuneo et al., Phys. Rev. Lett. 88, 215004 (2002)]. Point-projection x-ray imaging with the Z-Beamlet Laser mapped the trajectory and distortion of 2-mm diameter plastic ablator capsules. Using the backlit capsule distortion as a symmetry diagnostic, the ability to predictably tune symmetry at the 2 Legendre mode asymmetry coefficient over a range of ±6% (±2% considering points nearest the optimum) was achieved by varying the length of the cylindrical secondary hohlraum containing the capsule, in agreement with viewfactor and radiation-hydrodynamics simulations

First implosion experiments with cryogenic thermonuclear fuel on the National Ignition Facility

International Nuclear Information System (INIS)

Glenzer, Siegfried H; Spears, Brian K; Edwards, M John; Berger, Richard L; Bleuel, Darren L; Bradley, David K; Caggiano, Joseph A; Callahan, Debra A; Castro, Carlos; Choate, Christine; Clark, Daniel S; Cerjan, Charles J; Collins, Gilbert W; Dewald, Eduard L; Di Nicola, Jean-Michel G; Di Nicola, Pascale; Divol, Laurent; Dixit, Shamasundar N; Alger, Ethan T; Casey, Daniel T

2012-01-01

Non-burning thermonuclear fuel implosion experiments have been fielded on the National Ignition Facility to assess progress toward ignition by indirect drive inertial confinement fusion. These experiments use cryogenic fuel ice layers, consisting of mixtures of tritium and deuterium with large amounts of hydrogen to control the neutron yield and to allow fielding of an extensive suite of optical, x-ray and nuclear diagnostics. The thermonuclear fuel layer is contained in a spherical plastic capsule that is fielded in the center of a cylindrical gold hohlraum. Heating the hohlraum with 1.3 MJ of energy delivered by 192 laser beams produces a soft x-ray drive spectrum with a radiation temperature of 300 eV. The radiation field produces an ablation pressure of 100 Mbar which compresses the capsule to a spherical dense fuel shell that contains a hot plasma core 80 µm in diameter. The implosion core is observed with x-ray imaging diagnostics that provide size, shape, the absolute x-ray emission along with bangtime and hot plasma lifetime. Nuclear measurements provide the 14.1 MeV neutron yield from fusion of deuterium and tritium nuclei along with down-scattered neutrons at energies of 10–12 MeV due to energy loss by scattering in the dense fuel that surrounds the central hot-spot plasma. Neutron time-of-flight spectra allow the inference of the ion temperature while gamma-ray measurements provide the duration of nuclear activity. The fusion yield from deuterium–tritium reactions scales with ion temperature, which is in agreement with modeling over more than one order of magnitude to a neutron yield in excess of 10 14 neutrons, indicating large confinement parameters on these first experiments. (paper)

NIF capsule performance modeling

Directory of Open Access Journals (Sweden)

Weber S.

2013-11-01

Full Text Available Post-shot modeling of NIF capsule implosions was performed in order to validate our physical and numerical models. Cryogenic layered target implosions and experiments with surrogate targets produce an abundance of capsule performance data including implosion velocity, remaining ablator mass, times of peak x-ray and neutron emission, core image size, core symmetry, neutron yield, and x-ray spectra. We have attempted to match the integrated data set with capsule-only simulations by adjusting the drive and other physics parameters within expected uncertainties. The simulations include interface roughness, time-dependent symmetry, and a model of mix. We were able to match many of the measured performance parameters for a selection of shots.

Effects on Implosion Characteristics of High-Z Dopant Profiles in ICF Ignition Capsule Ablators

Science.gov (United States)

Li, Yongsheng; Wang, Min; Gu, Jianfa; Zou, Shiyang; Kang, Dongguo; Ye, Wenhua; Zhang, Weiyan

2012-10-01

For ignition target design (ITD) of indirect drive ICF [J. Lindl, PoP 2, 3933(1995)], high-Z dopants in capsule ablators were used to prevent preheat of DTadjacentablators by Au M-band flux in laser-driven gold Hohlraums, therefore to restrain the growth of high-mode hydro-instabilities and to improve the targetrobustness.Based on NIC's Rev. 5 ITD[S. W. Haan et al., PoP 18, 051001(2011)], we investigated the effect of thickness and dopant concentration of doped layers on implosion characteristics, including the Atwood number (AWN) of fuel-ablator interface, the density gradient scale length (DGSL) of ablation front and the implosion velocity (VIM); all three variables decrease with increment of dopant dosage, and increase with dopant concentration while keeping dosage constant. Since a smaller AWN, a larger DGSL, and a faster VIM always characterize a more robust ITD, one should make tradeoff among them by adjusting the dopant profiles in ablators.A Gaussian spectrum (GS) was used to imitate the Au M-band flux [Y. S. Li et al., PoP 18, 022701(2011)], and the impact of GScenter on implosion characteristics of Rev. 5 ITD was studied while moving the GScenter towards higher energy, the ablatorpreheat got severe, AWN got larger, DGSL got larger, and VIM got faster.

A near one-dimensional indirectly driven implosion at convergence ratio 30

Science.gov (United States)

MacLaren, S. A.; Masse, L. P.; Czajka, C. E.; Khan, S. F.; Kyrala, G. A.; Ma, T.; Ralph, J. E.; Salmonson, J. D.; Bachmann, B.; Benedetti, L. R.; Bhandarkar, S. D.; Bradley, P. A.; Hatarik, R.; Herrmann, H. W.; Mariscal, D. A.; Millot, M.; Patel, P. K.; Pino, J. E.; Ratledge, M.; Rice, N. G.; Tipton, R. E.; Tommasini, R.; Yeamans, C. B.

2018-05-01

Inertial confinement fusion cryogenic-layered implosions at the National Ignition Facility, while successfully demonstrating self-heating due to alpha-particle deposition, have fallen short of the performance predicted by one-dimensional (1D) multi-physics implosion simulations. The current understanding, from experimental evidence as well as simulations, suggests that engineering features such as the capsule tent and fill tube, as well as time-dependent low-mode asymmetry, are to blame for the lack of agreement. A short series of experiments designed specifically to avoid these degradations to the implosion are described here in order to understand if, once they are removed, a high-convergence cryogenic-layered deuterium-tritium implosion can achieve the 1D simulated performance. The result is a cryogenic layered implosion, round at stagnation, that matches closely the performance predicted by 1D simulations. This agreement can then be exploited to examine the sensitivity of approximations in the model to the constraints imposed by the data.

Numerical modeling of the sensitivity of x-ray driven implosions to low-mode flux asymmetries.

Science.gov (United States)

Scott, R H H; Clark, D S; Bradley, D K; Callahan, D A; Edwards, M J; Haan, S W; Jones, O S; Spears, B K; Marinak, M M; Town, R P J; Norreys, P A; Suter, L J

2013-02-15

The sensitivity of inertial confinement fusion implosions, of the type performed on the National Ignition Facility (NIF) [1], to low-mode flux asymmetries is investigated numerically. It is shown that large-amplitude, low-order mode shapes (Legendre polynomial P(4), resulting from low-order flux asymmetries, cause spatial variations in capsule and fuel momentum that prevent the deuterium and tritium (DT) "ice" layer from being decelerated uniformly by the hot spot pressure. This reduces the transfer of implosion kinetic energy to internal energy of the central hot spot, thus reducing the neutron yield. Furthermore, synthetic gated x-ray images of the hot spot self-emission indicate that P(4) shapes may be unquantifiable for DT layered capsules. Instead the positive P(4) asymmetry "aliases" itself as an oblate P(2) in the x-ray images. Correction of this apparent P(2) distortion can further distort the implosion while creating a round x-ray image. Long wavelength asymmetries may be playing a significant role in the observed yield reduction of NIF DT implosions relative to detailed postshot two-dimensional simulations.

Comparison of high-density carbon implosions in unlined uranium versus gold hohlraums

Science.gov (United States)

Dewald, Eduard; Meezan, Nathan; Tommasini, Riccardo; Khan, Shahab; MacKinnon, Andrew; Berzak Hopkins, Laura; Divol, Laurent; Lepape, Sebastien; Moore, Alastair; Schneider, Marilyn; Pak, Arthur; Nikroo, Abbas; Landen, Otto

2016-10-01

In Inertial Confinement Fusion (ICF) implosions, laser energy is converted to x-ray radiation in hohlraums with High-Z walls. At radiation temperatures near 300 eV relevant for ICF experiments, the radiative losses in heating the wall are lower for U than for Au hohlraums. Furthermore, the intensity of the ``M-band'' x-rays with photon energies h ν >1.8 keV is lower for uranium, allowing for reduced capsule dopant concentrations employed to minimize inner ablator preheat and hence keep favorable fuel/ablator interface Atwood numbers. This in turn improves the ablator rocket efficiency and reduces the risk of polluting the hot-spot with emissive dopant material. The first uranium vacuum hohlraum experiments on the National Ignition Facility (NIF) with undoped high-density carbon (HDC, or diamond) capsules have demonstrated 30% lower ``M-band'' intensity relative to Au, resulting in lower inflight ablator thickness due to reduced preheat. In addition, fusion neutron yields are 2x higher in U than in Au hohlraums for D2-gas filled capsule implosions at ICF relevant velocities of 380 +/-20 km/s. These results have led the NIF ICF implosions to routinely employ U hohlraums. Prepared by LLNL under Contract DE-AC52-07NA27344.

Exponential yield sensitivity to long-wavelength asymmetries in three-dimensional simulations of inertial confinement fusion capsule implosions

Energy Technology Data Exchange (ETDEWEB)

Haines, Brian M., E-mail: bmhaines@lanl.gov [Los Alamos National Laboratory, MS T087, Los Alamos, New Mexico 87545 (United States)

2015-08-15

In this paper, we perform a series of high-resolution 3D simulations of an OMEGA-type inertial confinement fusion (ICF) capsule implosion with varying levels of initial long-wavelength asymmetries in order to establish the physical energy loss mechanism for observed yield degradation due to long-wavelength asymmetries in symcap (gas-filled capsule) implosions. These simulations demonstrate that, as the magnitude of the initial asymmetries is increased, shell kinetic energy is increasingly retained in the shell instead of being converted to fuel internal energy. This is caused by the displacement of fuel mass away from and shell material into the center of the implosion due to complex vortical flows seeded by the long-wavelength asymmetries. These flows are not fully turbulent, but demonstrate mode coupling through non-linear instability development during shell stagnation and late-time shock interactions with the shell interface. We quantify this effect by defining a separation lengthscale between the fuel mass and internal energy and show that this is correlated with yield degradation. The yield degradation shows an exponential sensitivity to the RMS magnitude of the long-wavelength asymmetries. This strong dependence may explain the lack of repeatability frequently observed in OMEGA ICF experiments. In contrast to previously reported mechanisms for yield degradation due to turbulent instability growth, yield degradation is not correlated with mixing between shell and fuel material. Indeed, an integrated measure of mixing decreases with increasing initial asymmetry magnitude due to delayed shock interactions caused by growth of the long-wavelength asymmetries without a corresponding delay in disassembly.

Measuring symmetry of implosions in cryogenic Hohlraums at the NIF using gated x-ray detectors (invited).

Science.gov (United States)

Kyrala, G A; Dixit, S; Glenzer, S; Kalantar, D; Bradley, D; Izumi, N; Meezan, N; Landen, O L; Callahan, D; Weber, S V; Holder, J P; Glenn, S; Edwards, M J; Bell, P; Kimbrough, J; Koch, J; Prasad, R; Suter, L; Kline, J L; Kilkenny, J

2010-10-01

Ignition of imploding inertial confinement capsules requires, among other things, controlling the symmetry with high accuracy and fidelity. We have used gated x-ray imaging, with 10 μm and 70 ps resolution, to detect the x-ray emission from the imploded core of symmetry capsules at the National Ignition Facility. The measurements are used to characterize the time dependent symmetry and the x-ray bang time of the implosion from two orthogonal directions. These measurements were one of the primary diagnostics used to tune the parameters of the laser and Hohlraum to vary the symmetry and x-ray bang time of the implosion of cryogenically cooled ignition scale deuterium/helium filled plastic capsules. Here, we will report on the successful measurements performed with up to 1.2 MJ of laser energy in a fully integrated cryogenics gas-filled ignition-scale Hohlraum and capsule illuminated with 192 smoothed laser beams. We will describe the technique, the accuracy of the technique, and the results of the variation in symmetry with tuning parameters, and explain how that set was used to predictably tune the implosion symmetry as the laser energy, the laser cone wavelength separation, and the Hohlraum size were increased to ignition scales. We will also describe how to apply that technique to cryogenically layered tritium-hydrogen-deuterium capsules.

Implosion spectroscopy in Rugby hohlraums on OMEGA

Science.gov (United States)

Philippe, Franck; Tassin, Veronique; Bitaud, Laurent; Seytor, Patricia; Reverdin, Charles

2014-10-01

The rugby hohlraum concept has been validated in previous experiments on the OMEGA laser facility. This new hohlraum type can now be used as a well-characterized experimental platform to study indirect drive implosion, at higher radiation temperatures than would be feasible at this scale with classical cylindrical hohlraums. Recent experiments have focused on the late stages of implosion and hotspot behavior. The capsules included both a thin buried Titanium tracer layer, 0-3 microns from the inner surface, Argon dopant in the deuterium gas fuel and Germanium doped CH shells, providing a variety of spectral signatures of the plasma conditions in different parts of the target. X-ray spectroscopy and imaging were used to study compression, Rayleigh-Taylor instabilities growth at the inner surface and mix between the shell and gas.

Designing symmetric polar direct drive implosions on the Omega laser facility

Energy Technology Data Exchange (ETDEWEB)

Krasheninnikova, Natalia S.; Cobble, James A.; Murphy, Thomas J.; Tregillis, Ian L.; Bradley, Paul A.; Hakel, Peter; Hsu, Scott C.; Kyrala, George A.; Obrey, Kimberly A.; Schmitt, Mark J.; Baumgaertel, Jessica A.; Batha, Steven H. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2014-04-15

Achieving symmetric capsule implosions with Polar Direct Drive [S. Skupsky et al., Phys. Plasmas 11, 2763 (2004); R. S. Craxton et al., Phys. Plasmas 12, 056304 (2005); F. J. Marshall et al., J. Phys. IV France 133, 153–157 (2006)] has been explored during recent Defect Induced Mix Experiment campaign on the Omega facility at the Laboratory for Laser Energetics. To minimize the implosion asymmetry due to laser drive, optimized laser cone powers, as well as improved beam pointings, were designed using 3D radiation-hydrodynamics code HYDRA [M. M. Marinak et al., Phys. Plasmas 3, 2070 (1996)]. Experimental back-lit radiographic and self-emission images revealed improved polar symmetry and increased neutron yield which were in good agreement with 2D HYDRA simulations. In particular, by reducing the energy in Omega's 21.4° polar rings by 16.75%, while increasing the energy in the 58.9° equatorial rings by 8.25% in such a way as to keep the overall energy to the target at 16 kJ, the second Legendre mode (P{sub 2}) was reduced by a factor of 2, to less than 4% at bang time. At the same time the neutron yield increased by 62%. The polar symmetry was also improved relative to nominal DIME settings by a more radical repointing of OMEGA's 42.0° and 58.9° degree beams, to compensate for oblique incidence and reduced absorption at the equator, resulting in virtually no P{sub 2} around bang time and 33% more yield.

Asymmetric-shell ignition capsule design to tune the low-mode asymmetry during the peak drive

International Nuclear Information System (INIS)

Gu, Jianfa; Dai, Zhensheng; Song, Peng; Zou, Shiyang; Ye, Wenhua; Zheng, Wudi; Gu, Peijun; Wang, Jianguo; Zhu, Shaoping

2016-01-01

The low-mode radiation flux asymmetry in the hohlraum is a main source of performance degradation in the National Ignition Facility (NIF) implosion experiments. To counteract the deleterious effects of the large positive P2 flux asymmetry during the peak drive, this paper develops a new tuning method called asymmetric-shell ignition capsule design which adopts the intentionally asymmetric CH ablator layer or deuterium-tritium (DT) ice layer. A series of two-dimensional implosion simulations have been performed, and the results show that the intentionally asymmetric DT ice layer can significantly improve the fuel ρR symmetry, hot spot shape, hot spot internal energy, and the final neutron yield compared to the spherical capsule. This indicates that the DT asymmetric-shell capsule design is an effective tuning method, while the CH ablator asymmetric-shell capsule could not correct the fuel ρR asymmetry, and it is not as effective as the DT asymmetric-shell capsule design.

Asymmetric-shell ignition capsule design to tune the low-mode asymmetry during the peak drive

Science.gov (United States)

Gu, Jianfa; Dai, Zhensheng; Song, Peng; Zou, Shiyang; Ye, Wenhua; Zheng, Wudi; Gu, Peijun; Wang, Jianguo; Zhu, Shaoping

2016-08-01

The low-mode radiation flux asymmetry in the hohlraum is a main source of performance degradation in the National Ignition Facility (NIF) implosion experiments. To counteract the deleterious effects of the large positive P2 flux asymmetry during the peak drive, this paper develops a new tuning method called asymmetric-shell ignition capsule design which adopts the intentionally asymmetric CH ablator layer or deuterium-tritium (DT) ice layer. A series of two-dimensional implosion simulations have been performed, and the results show that the intentionally asymmetric DT ice layer can significantly improve the fuel ρR symmetry, hot spot shape, hot spot internal energy, and the final neutron yield compared to the spherical capsule. This indicates that the DT asymmetric-shell capsule design is an effective tuning method, while the CH ablator asymmetric-shell capsule could not correct the fuel ρR asymmetry, and it is not as effective as the DT asymmetric-shell capsule design.

Asymmetric-shell ignition capsule design to tune the low-mode asymmetry during the peak drive

Energy Technology Data Exchange (ETDEWEB)

Gu, Jianfa, E-mail: gu-jianfa@iapcm.ac.cn; Dai, Zhensheng, E-mail: dai-zhensheng@iapcm.ac.cn; Song, Peng; Zou, Shiyang; Ye, Wenhua; Zheng, Wudi; Gu, Peijun; Wang, Jianguo; Zhu, Shaoping [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

2016-08-15

The low-mode radiation flux asymmetry in the hohlraum is a main source of performance degradation in the National Ignition Facility (NIF) implosion experiments. To counteract the deleterious effects of the large positive P2 flux asymmetry during the peak drive, this paper develops a new tuning method called asymmetric-shell ignition capsule design which adopts the intentionally asymmetric CH ablator layer or deuterium-tritium (DT) ice layer. A series of two-dimensional implosion simulations have been performed, and the results show that the intentionally asymmetric DT ice layer can significantly improve the fuel ρR symmetry, hot spot shape, hot spot internal energy, and the final neutron yield compared to the spherical capsule. This indicates that the DT asymmetric-shell capsule design is an effective tuning method, while the CH ablator asymmetric-shell capsule could not correct the fuel ρR asymmetry, and it is not as effective as the DT asymmetric-shell capsule design.

Shock timing on the National Ignition Facility: First Experiments

International Nuclear Information System (INIS)

Celliers, P.M.; Robey, H.F.; Boehly, T.R.; Alger, E.; Azevedo, S.; Berzins, L.V.; Bhandarkar, S.D.; Bowers, M.W.; Brereton, S.J.; Callahan, D.; Castro, C.; Chandrasekaran, H.; Choate, C.; Clark, D.; Coffee, K.R.; Datte, P.S.; Dewald, E.L.; DiNicola, P.; Dixit, S.; Doeppner, T.; Dzenitis, E.; Edwards, M.J.; Eggert, J.H.; Fair, J.; Farley, D.R.; Frieders, G.; Gibson, C.R.; Giraldez, E.; Haan, S.; Haid, B.; Hamza, A.V.; Haynam, C.; Hicks, D.G.; Holunga, D.M.; Horner, J.B.; Jancaitis, K.; Jones, O.S.; Kalantar, D.; Kline, J.L.; Krauter, K.G.; Kroll, J.J.; LaFortune, K.N.; Pape, S.L.; Malsbury, T.; Maypoles, E.R.; Milovich, J.L.; Moody, J.D.; Moreno, K.; Munro, D.H.; Nikroo, A.; Olson, R.E.; Parham, T.; Pollaine, S.; Radousky, H.B.; Ross, G.F.; Sater, J.; Schneider, M.B.; Shaw, M.; Smith, R.F.; Thomas, C.A.; Throop, A.; Town, R.J.; Trummer, D.; Van Wonterghem, B.M.; Walters, C.F.; Widmann, K.; Widmayer, C.; Young, B.K.; Atherton, L.J.; Collins, G.W.; Landen, O.L.; Lindl, J.D.; MacGowan, B.J.; Meyerhofer, D.D.; Moses, E.I.

2011-01-01

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 reentrant 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.

Validating Inertial Confinement Fusion (ICF) predictive capability using perturbed capsules

Science.gov (United States)

Schmitt, Mark; Magelssen, Glenn; Tregillis, Ian; Hsu, Scott; Bradley, Paul; Dodd, Evan; Cobble, James; Flippo, Kirk; Offerman, Dustin; Obrey, Kimberly; Wang, Yi-Ming; Watt, Robert; Wilke, Mark; Wysocki, Frederick; Batha, Steven

2009-11-01

Achieving ignition on NIF is a monumental step on the path toward utilizing fusion as a controlled energy source. Obtaining robust ignition requires accurate ICF models to predict the degradation of ignition caused by heterogeneities in capsule construction and irradiation. LANL has embarked on a project to induce controlled defects in capsules to validate our ability to predict their effects on fusion burn. These efforts include the validation of feature-driven hydrodynamics and mix in a convergent geometry. This capability is needed to determine the performance of capsules imploded under less-than-optimum conditions on future IFE facilities. LANL's recently initiated Defect Implosion Experiments (DIME) conducted at Rochester's Omega facility are providing input for these efforts. Recent simulation and experimental results will be shown.

Capsule safety analysis of PRTF irradiation facility

International Nuclear Information System (INIS)

Suwarto

2013-01-01

Power Ramp Test Facility (PRTF) is an irradiation facility used for fuel testing of power reactor. PRTF has a capsule which is a test fuel rod container. During operation, pressurized water of 160 bars flows through in the capsule. Due to the high pressure it should be analyzed the impact of the capsule on reactor core safety. This analysis has purpose to calculate the ability of capsule pressure capacity. The analysis was carried out by calculating pressure capacity. From the calculating results it can be concluded that the capsule with pressure capacity of 438 bars will be safe to prevent the operation pressure of PRTF. (author)

A near one-dimensional 2-shock indirectly driven implosion at convergence ratio 30

Science.gov (United States)

MacLaren, Steve

2017-10-01

Inertial confinement fusion implosions at the National Ignition Facility, while successfully demonstrating self-heating due to alpha-particle deposition, have fallen short of the performance predicted by one-dimensional multi-physics implosion simulations. The current understanding, based on simulations as well as experimental evidence, suggests that the principle reason for the disagreement is a breeching of the cold fuel assembly at stagnation which would otherwise completely confine the hot spot. 3-D simulations indicate a combination of low-mode symmetry swings and ablation-front hydrodynamic instability seeded by engineering features such as the capsule tent and fill tube lead to localized thinning and perforation of the stagnated fuel, resulting in a loss of hot spot pressure and energy. We describe a short series of experiments on the NIF designed specifically to avoid these issues in order to understand if, once they are removed, a suspended-fuel-layer deuterium-tritium implosion can achieve 1-D simulated performance. The particular implosion system combines a thick capsule shell with an elevated initial ablation temperature to minimize the ablation front perturbations from the engineering features, and incorporates a large ratio of hohlraum-to-capsule radius as a means to permit a higher degree of control over implosion symmetry. The resulting implosion at a convergence ratio of 30 was not perfectly spherically symmetric as observed by both neutron and time-resolved x-ray imaging diagnostics. However, the stagnation observables match closely the performance predicted by 1D simulations, including, when some hot spot motion is accounted for, the apparent ion temperature. We present this result along with the design for an upcoming 2-shock experiment to test whether this level of agreement with the 1D model can be achieved in the self-heating regime. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under

Hydrodynamic instability growth of three-dimensional, “native-roughness” modulations in x-ray driven, spherical implosions at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Smalyuk, V. A.; Weber, S. V.; Casey, D. T.; Clark, D. S.; Field, J. E.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Landen, O. L.; Robey, H. F.; Weber, C. R. [Lawrence Livermore National Laboratory, NIF Directorate, Livermore, California 94550 (United States); Hoover, D. E.; Nikroo, A. [General Atomics, San Diego, California 92186 (United States)

2015-07-15

Hydrodynamic instability growth experiments with three-dimensional (3-D) surface-roughness modulations were performed on plastic (CH) shell spherical implosions at the National Ignition Facility (NIF) [E. M. Campbell, R. Cauble, and B. A. Remington, AIP Conf. Proc. 429, 3 (1998)]. The initial capsule outer-surface roughness was similar to the standard specifications (“native roughness”) used in a majority of implosions on NIF. The experiments included instability growth measurements of the perturbations seeded by the thin membranes (or tents) used to hold the capsules inside the hohlraums. In addition, initial modulations included two divots used as spatial fiducials to determine the convergence in the experiments and to check the accuracy of 3D simulations in calculating growth of known initial perturbations. The instability growth measurements were performed using x-ray, through-foil radiography of one side of the imploding shell, based on time-resolved pinhole imaging. Averaging over 30 similar images significantly increases the signal-to-noise ratio, making possible a comparison with 3-D simulations. At a convergence ratio of ∼3, the measured tent and divot modulations were close to those predicted by 3-D simulations (within ∼15%–20%), while measured 3-D, broadband modulations were ∼3–4 times larger than those simulated based on the growth of the known imposed initial surface modulations. In addition, some of the measured 3-D features in x-ray radiographs did not resemble those characterized on the outer capsule surface before the experiments. One of the hypotheses to explain the results is based on the increased instability amplitudes due to modulations of the oxygen content in the bulk of the capsule. As the target assembly and handling procedures involve exposure to UV light, this can increase the uptake of the oxygen into the capsule, with irregularities in the oxygen seeding hydrodynamic instabilities. These new experimental results have

Multidimensional Analysis of Direct-Drive Plastic-Shell Implosions on OMEGA

Science.gov (United States)

Radha, P. B.

2004-11-01

Direct-drive implosions of plastic shells with the OMEGA laser are used as energy-scaled warm surrogates for ignition cryogenic targets designed for use on the National Ignition Facility. Plastic targets involve varying shell thickness (15 to 33 μm), fill pressures (3 to 15 atm), and shell adiabats. The multidimensional hydrodynamics code DRACO is used to evaluate the effects of capsule-surface roughness and illumination nonuniformities on target performance. These simulations indicate that shell stability during the acceleration phase plays a critical role in determining fusion yields. For shells that are thick enough to survive the Rayleigh--Taylor growth, target yields are significantly reduced by growth of the long (ℓ surrogacy between these plastic-shell implosions and the cryogenic ignition designs.

Diagnostics and equipment for ion temperatures and implosion neutron yields

International Nuclear Information System (INIS)

Chen Jiabin; Zheng Zhijian; Peng Hansheng; Wen Shuhuai; Zhang Baohan; Ding Yongkun; Qi Lanying; Chen Ming; Li Chaoguang

2001-01-01

Fuel ion temperature is of great importance in the ICF research field. A set of ultra-fast quenched plastic scintillation detector system was fabricated for low yield neutron diagnostic. The detection efficiency and the sensitivity to DT neutrons were scaled using a K-400 accelerator and a pulse neutron tube from Russia with a width 5 - 10 ns, respectively. Its time response functions were calibrated by cosmic ray and implosion neutron separately. Under the conditions of low laser energy so low neutron yield and very limited space, fuel ion temperatures (including implosion neutron yields at the same time) were obtained. The measured ion temperatures for exploding pusher capsules were between 4 keV and 5 keV with errors +-(15 - 25)%. The neutron yields were 5 x 10 8 - 3 x 10 9 for exploding pusher capsules and 1.6 x 10 7 - 3.9 x 10 8 for ablation ones with errors +- (7 - 10)%. Of the six shots of neutron yields calculated, five are in good agreement with authors' experimental results in the range of +- 20%. Not only the heat-conducting mechanism and the effects on implosion of the energy balance of each path of incidence laser, target design, fuel mixture as well as hot electron behavior have been investigated, but also the upgrade level of the laser facility Shengguang II has been tested

Shock timing on the National Ignition Facility: First experiments

Directory of Open Access Journals (Sweden)

Celliers P.M.

2013-11-01

Full Text Available 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.

The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

Energy Technology Data Exchange (ETDEWEB)

Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2014-11-15

The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D{sup 3}He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D{sup 3}He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (R{sub cm}) from the downshift of the shock-produced D{sup 3}He protons. The observed ρR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time (“short-coast”), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (∼800 ps) than in the short-coast (∼400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel ρR.

The effect of shock dynamics on compressibility of ignition-scale National Ignition Facility implosions

International Nuclear Information System (INIS)

Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W.; Hicks, D. G.; Dewald, E. L.; Robey, H. F.; Rygg, J. R.; Meezan, N. B.; Friedrich, S.; Bionta, R.; Atherton, J.; Barrios, M.

2014-01-01

The effects of shock dynamics on compressibility of indirect-drive ignition-scale surrogate implosions, CH shells filled with D 3 He gas, have been studied using charged-particle spectroscopy. Spectral measurements of D 3 He protons produced at the shock-bang time probe the shock dynamics and in-flight characteristics of an implosion. The proton shock yield is found to vary by over an order of magnitude. A simple model relates the observed yield to incipient hot-spot adiabat, suggesting that implosions with rapid radiation-power increase during the main drive pulse may have a 2× higher hot-spot adiabat, potentially reducing compressibility. A self-consistent 1-D implosion model was used to infer the areal density (ρR) and the shell center-of-mass radius (R cm ) from the downshift of the shock-produced D 3 He protons. The observed ρR at shock-bang time is substantially higher for implosions, where the laser drive is on until near the compression bang time (“short-coast”), while longer-coasting implosions have lower ρR. This corresponds to a much larger temporal difference between the shock- and compression-bang time in the long-coast implosions (∼800 ps) than in the short-coast (∼400 ps); this will be verified with a future direct bang-time diagnostic. This model-inferred differential bang time contradicts radiation-hydrodynamic simulations, which predict constant 700–800 ps differential independent of coasting time; this result is potentially explained by uncertainties in modeling late-time ablation drive on the capsule. In an ignition experiment, an earlier shock-bang time resulting in an earlier onset of shell deceleration, potentially reducing compression and, thus, fuel ρR

Research on the influence of the scattering laser on implosion

International Nuclear Information System (INIS)

Li Meng; Li Yunsheng; Fu Shangwu

2003-01-01

In the indirect driven implosion, the scattering laser from the hohlraum wall will partially irradiate on the capsule and influence its implosion. Based on the research of one-dimensional and two-dimensional numerical simulations, detailed analyses are pursued to give the influence of the scattering laser on the implosion and the explanation of the influence. (authors)

ICF in the U.S.: Facilities and diagnostics

International Nuclear Information System (INIS)

Coleman, L.W.

1988-08-01

In the last few years there has been significant progress in ICF research in laboratories in the United States and elsewhere. These advances have occurred in areas that range from demonstrating an innovative laser beam smoothing techniques important for both directly and indirectly driven ICF, to achieving a more complete understanding of capsule implosions and related physics. This progress has been possible because of the capabilities provided by the ICF laser-target facilities currently in operation and the new developments in diagnostics, particularly for measurements of the implosion process and the conditions in the compressed capsule core. Both of these topics, facilities and selected new diagnostics capabilities in the US ICF Program, are summarized in this paper. 32 refs., 19 figs., 6 tabs

Symmetry tuning with megajoule laser pulses at the National Ignition Facility

Directory of Open Access Journals (Sweden)

Kline J.L.

2013-11-01

Full Text Available 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.

Mode 1 drive asymmetry in inertial confinement fusion implosions on the National Ignition Facility

International Nuclear Information System (INIS)

Spears, Brian K.; Edwards, M. J.; Hatchett, S.; Kritcher, A.; Lindl, J.; Munro, D.; Patel, P.; Robey, H. F.; Town, R. P. J.; Kilkenny, J.; Knauer, J.

2014-01-01

Mode 1 radiation drive asymmetry (pole-to-pole imbalance) at significant levels can have a large impact on inertial confinement fusion implosions at the National Ignition Facility (NIF). This asymmetry distorts the cold confining shell and drives a high-speed jet through the hot spot. The perturbed hot spot shows increased residual kinetic energy and reduced internal energy, and it achieves reduced pressure and neutron yield. The altered implosion physics manifests itself in observable diagnostic signatures, especially the neutron spectrum which can be used to measure the neutron-weighted flow velocity, apparent ion temperature, and neutron downscattering. Numerical simulations of implosions with mode 1 asymmetry show that the resultant simulated diagnostic signatures are moved toward the values observed in many NIF experiments. The diagnostic output can also be used to build a set of integrated implosion performance metrics. The metrics indicate that P 1 has a significant impact on implosion performance and must be carefully controlled in NIF implosions

Mode 1 drive asymmetry in inertial confinement fusion implosions on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Spears, Brian K., E-mail: spears9@llnl.gov; Edwards, M. J.; Hatchett, S.; Kritcher, A.; Lindl, J.; Munro, D.; Patel, P.; Robey, H. F.; Town, R. P. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Kilkenny, J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Knauer, J. [Laboratory for Laser Energetics, 250 E. River Road Rochester, New York 14623-1212 (United States)

2014-04-15

Mode 1 radiation drive asymmetry (pole-to-pole imbalance) at significant levels can have a large impact on inertial confinement fusion implosions at the National Ignition Facility (NIF). This asymmetry distorts the cold confining shell and drives a high-speed jet through the hot spot. The perturbed hot spot shows increased residual kinetic energy and reduced internal energy, and it achieves reduced pressure and neutron yield. The altered implosion physics manifests itself in observable diagnostic signatures, especially the neutron spectrum which can be used to measure the neutron-weighted flow velocity, apparent ion temperature, and neutron downscattering. Numerical simulations of implosions with mode 1 asymmetry show that the resultant simulated diagnostic signatures are moved toward the values observed in many NIF experiments. The diagnostic output can also be used to build a set of integrated implosion performance metrics. The metrics indicate that P{sub 1} has a significant impact on implosion performance and must be carefully controlled in NIF implosions.

Variable convergence liquid layer implosions on the National Ignition Facility

Science.gov (United States)

Zylstra, A. B.; Yi, S. A.; Haines, B. M.; Olson, R. E.; Leeper, R. J.; Braun, T.; Biener, J.; Kline, J. L.; Batha, S. H.; Berzak Hopkins, L.; Bhandarkar, S.; Bradley, P. A.; Crippen, J.; Farrell, M.; Fittinghoff, D.; Herrmann, H. W.; Huang, H.; Khan, S.; Kong, C.; Kozioziemski, B. J.; Kyrala, G. A.; Ma, T.; Meezan, N. B.; Merrill, F.; Nikroo, A.; Peterson, R. R.; Rice, N.; Sater, J. D.; Shah, R. C.; Stadermann, M.; Volegov, P.; Walters, C.; Wilson, D. C.

2018-05-01

Liquid layer implosions using the "wetted foam" technique, where the liquid fuel is wicked into a supporting foam, have been recently conducted on the National Ignition Facility for the first time [Olson et al., Phys. Rev. Lett. 117, 245001 (2016)]. We report on a series of wetted foam implosions where the convergence ratio was varied between 12 and 20. Reduced nuclear performance is observed as convergence ratio increases. 2-D radiation-hydrodynamics simulations accurately capture the performance at convergence ratios (CR) ˜ 12, but we observe a significant discrepancy at CR ˜ 20. This may be due to suppressed hot-spot formation or an anomalous energy loss mechanism.

Utilization of the capsule out-pile test facilities(2000-2003)

Energy Technology Data Exchange (ETDEWEB)

Cho, M. S.; Oh, J. M.; Cho, Y. G. and others

2003-06-01

Two out-pile test facilities were installed and being utilized for the non-irradiation tests outside the HANARO. The names of the facilities are the irradiation equipment design verification test facilities and the one-channel flow test device. In these facilities, the performance test of all capsules manufactured before loading in the HANARO and the design verification test for newly developed capsules were performed. The tests in these facilities include loading/unloading, pressure drop, endurance and vibration test etc. of capsules. In the period 2000{approx}2003, the performance tests for 8 material capsules of 99M-01K{approx}02M-05U were carried out, and the design verification tests of creep and fuel capsules developed newly were performed. For development of the creep capsule, pressure drop measurement, operation test of heater, T/C, LVDT and stress loading test were performed. In the design stage of the fuel capsule, the endurance and vibration test besides the above mentioned tests were carried out for verification of the safe operation during irradiation test in the HANARO. And in-chimeny bracket and the capsule supporting system were fixed and the flow tubes and the handling tools were manufactured for use at the facilities.

Imaging of High-Energy X-Ray Emission from Cryogenic Thermonuclear Fuel Implosions on the NIF

International Nuclear Information System (INIS)

Ma, T.

2012-01-01

Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide spectrally resolved time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered targets. Using bremsstrahlung assumptions, the measured absolute x-ray brightness allows for the inference of electron temperature, electron density, hot spot mass, mix mass, and pressure. Current inertial confinement fusion (ICF) experiments conducted on the National Ignition Facility (NIF) seek to indirectly drive a spherical implosion, compressing and igniting a deuterium-tritium fuel. This DT fuel capsule is cryogenically prepared as a solid ice layer surrounded by a low-Z ablator material. Ignition will occur when the hot spot approaches sufficient temperature (∼3-4 keV) and ρR (∼0.3 g/cm 2 ) such that alpha deposition can further heat the hot spot and generate a self-sustaining burn wave. During the implosion, the fuel mass becomes hot enough to emit large amounts of x-ray radiation, the spectra and spatial variation of which contains key information that can be used to evaluate the implosion performance. The Ross filter diagnostic employs differential filtering to provide spectrally resolved, time-integrated, absolute x-ray self-emission images of the imploded core of cryogenic layered targets.

First Liquid Layer Inertial Confinement Fusion Implosions at the National Ignition Facility

Science.gov (United States)

Olson, R. E.; Leeper, R. J.; Kline, J. L.; Zylstra, A. B.; Yi, S. A.; Biener, J.; Braun, T.; Kozioziemski, B. J.; Sater, J. D.; Bradley, P. A.; Peterson, R. R.; Haines, B. M.; Yin, L.; Berzak Hopkins, L. F.; Meezan, N. B.; Walters, C.; Biener, M. M.; Kong, C.; Crippen, J. W.; Kyrala, G. A.; Shah, R. C.; Herrmann, H. W.; Wilson, D. C.; Hamza, A. V.; Nikroo, A.; Batha, S. H.

2016-12-01

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D2 and DT layer inertial confinement fusion (ICF) implosions that can access a low-to-moderate hot-spot convergence ratio (12 30 ) DT ice layer implosions. Although high CR is desirable in an idealized 1D sense, it amplifies the deleterious effects of asymmetries. To date, these asymmetries prevented the achievement of ignition at the NIF and are the major cause of simulation-experiment disagreement. In the initial liquid layer experiments, high neutron yields were achieved with CRs of 12-17, and the hot-spot formation is well understood, demonstrated by a good agreement between the experimental data and the radiation hydrodynamic simulations. These initial experiments open a new NIF experimental capability that provides an opportunity to explore the relationship between hot-spot convergence ratio and the robustness of hot-spot formation during ICF implosions.

Three-dimensional modeling of direct-drive cryogenic implosions on OMEGA

International Nuclear Information System (INIS)

Igumenshchev, I. V.; Goncharov, V. N.; Marshall, F. J.; Knauer, J. P.; Campbell, E. M.

2016-01-01

The effects of large-scale (with Legendre modes ≲10) laser-imposed nonuniformities in direct-drive cryogenic implosions on the OMEGA laser system are investigated using three-dimension hydrodynamic simulations performed using a newly developed code ASTER. Sources of these nonuniformities include an illumination pattern produced by 60 OMEGA laser beams, capsule offsets (~10 to 20 μm), and imperfect pointing, energy balance, and timing of the beams (with typical σ rms ~10 μm, 10%, and 5 ps, respectively). Two implosion designs using 26-kJ triple-picket laser pulses were studied: a nominal design, in which a 880-μm-diameter capsule is illuminated by the same-diameter beams, and a “R75” design using a capsule of 900 μm in diameter and beams of 75% of this diameter. Simulations found that nonuniformities because of capsule offsets and beam imbalance have the largest effect on implosion performance. These nonuniformities lead to significant distortions of implosion cores resulting in an incomplete stagnation. The shape of distorted cores is well represented by neutron images, but loosely in x-rays. Simulated neutron spectra from perturbed implosions show large directional variations and up to ~ 2 keV variation of the hot spot temperature inferred from these spectra. The R75 design is more hydrodynamically efficient because of mitigation of crossed-beam energy transfer, but also suffers more from the nonuniformities. Furthermore, simulations predict a performance advantage of this design over the nominal design when the target offset and beam imbalance σ rms are reduced to less than 5 μm and 5%, respectively

Gas-filled Rugby hohlraum energetics and implosions experiments on OMEGA

Science.gov (United States)

Casner, Alexis; Philippe, F.; Tassin, V.; Seytor, P.; Monteil, M. C.; Villette, B.; Reverdin, C.

2010-11-01

Recent experiments [1,2] have validated the x-ray drive enhancement provided by rugby-shaped hohlraums over cylinders in the indirect drive (ID) approach to inertial confinement fusion (ICF). This class of hohlraum is the baseline design for the Laser Mégajoule program, is also applicable to the National Ignition Facility and could therefore benefit ID Inertial Fusion Energy studies. We have carried out a serie of energetics and implosions experiments with OMEGA ``scale 1'' rugby hohlraums [1,2]. For empty hohlraums these experiments provide complementary measurements of backscattered light along 42 cone, as well as detailed drive history. In the case of gas-filled rugby hohlraums we have also study implosion performance (symmetry, yield, bangtime, hotspot spectra...) using a high contrast shaped pulse leading to a different implosion regime and for a range of capsule convergence ratios. These results will be compared with FCI2 hydrocodes calculations and future experimental campaigns will be suggested. [4pt] [1] F. Philippe et al., Phys. Rev. Lett. 104, 035004 (2010). [0pt] [2] H. Robey et al., Phys. Plasnas 17, 056313 (2010).

Development of new platforms for hydrodynamic instability and asymmetry measurements in deceleration phase of indirectly-driven implosions on NIF

Science.gov (United States)

Pickworth, Louisa

2017-10-01

Hydrodynamic instabilities and asymmetries are a major obstacle in the quest to achieve ignition as they cause pre-existing capsule perturbations to grow and ultimately quench the fusion burn in experiments at the National Ignition Facility (NIF). This talk will review recent developments of the experimental platforms and techniques to measure high-mode instabilities and low-mode asymmetries in the deceleration phase of implosions. These new platforms provide a natural link between the acceleration-phase experiments and neutron performance of layered deuterium-tritium implosions. In one innovative technique, self-emission from the hot spot was enhanced with argon dopant to ``self-backlight'' the shell in-flight around peak compression. Experiments with pre-imposed 2-D perturbations measured instability growth factors, while experiments with 3-D, ``native-roughness'' perturbations measured shell integrity in the deceleration phase of implosions. In a complimentary technique, the inner surface of the shell, along with its low-mode asymmetries and high-mode perturbations were visualized in implosions using x-ray emission of a high-Z dopant added to the inner surface of the capsule. These new measurements were instrumental in revealing unexpected surprises and providing improved understanding of the role of instabilities and asymmetries on implosion performance. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Polar tent for reduced perturbation of NIF ignition capsules

Science.gov (United States)

Hammel, B. A.; Pickworth, L.; Stadermann, M.; Field, J.; Robey, H.; Scott, H. A.; Smalyuk, V.

2016-10-01

In simulations, a tent that contacts the capsule near the poles and departs tangential to the capsule surface greatly reduces the capsule perturbation, and the resulting mass injected into the hot-spot, compared to current capsule support methods. Target fabrication appears feasible with a layered tent (43-nm polyimide + 8-nm C) for increased stiffness. We are planning quantitative measurements of the resulting shell- ρR perturbation near peak implosion velocity (PV) using enhanced self-emission backlighting, achieved by adding 1% Ar to the capsule fill in Symcaps (4He + H). Layered DT implosions are also planned for an integrated test of capsule performance. We will describe the design and simulation predictions. Prepared by LLNL under Contract DE-AC52-07NA27344.

Maximizing 1D “like” implosion performance for inertial confinement fusion science

Energy Technology Data Exchange (ETDEWEB)

Kline, John L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-07-15

While the march towards achieving indirectly driven inertial confinement fusion at the NIF has made great progress, the experiments show that multi-dimensional effects still dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seed by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of ICF implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. To this end, LANL has adopted three main approaches to develop a 1D implosion platform where 1D means high yield over 1D clean calculations. Taking advantage of the properties of beryllium capsules, a high adiabat, low convergence platform is being developed. The higher drive efficiency for beryllium enables larger case-to-capsule ratios to improve symmetry at the expense of drive. Smaller capsules with a high adiabat drive are expected to reduce the convergence and thus increase predictability. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the initial mass in the hot spot can be controlled via the target fielding temperature which changes the liquid vapor pressure. Varying the initial hot spot mass via the vapor pressure controls the implosion convergence and minimizes the need to vaporize the dense fuel layer during the implosion to achieve ignition relevant hot spot densities. The last method is double shell targets. Unlike hot spot ignition, double shells ignite volumetrically. The inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. Radiation trapping and the longer confinement times relax the conditions required to ignite the fuel. Key challenges for double shell targets are coupling the momentum of the outer shell to

Development of a krypton-doped gas symmetry capsule platform for x-ray spectroscopy of implosion cores on the NIF

Energy Technology Data Exchange (ETDEWEB)

Ma, T., E-mail: ma8@llnl.gov; Chen, H.; Patel, P. K.; Schneider, M. B.; Barrios, M. A.; Casey, D. T.; Hammel, B. A.; Berzak Hopkins, L. F.; Jarrott, L. C.; Khan, S. F.; Nora, R.; Pak, A.; Scott, H. A.; Spears, B. K.; Weber, C. R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Chung, H.-K. [International Atomic Energy Agency, Vienna (Austria); Lahmann, B.; Sio, H. [Plasma Fusion and Science Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Rosenberg, M. J.; Regan, S. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2016-11-15

The electron temperature at stagnation of an ICF implosion can be measured from the emission spectrum of high-energy x-rays that pass through the cold material surrounding the hot stagnating core. Here we describe a platform developed on the National Ignition Facility where trace levels of a mid-Z dopant (krypton) are added to the fuel gas of a symcap (symmetry surrogate) implosion to allow for the use of x-ray spectroscopy of the krypton line emission.

Development of a krypton-doped gas symmetry capsule platform for x-ray spectroscopy of implosion cores on the NIF.

Science.gov (United States)

Ma, T; Chen, H; Patel, P K; Schneider, M B; Barrios, M A; Casey, D T; Chung, H-K; Hammel, B A; Berzak Hopkins, L F; Jarrott, L C; Khan, S F; Lahmann, B; Nora, R; Rosenberg, M J; Pak, A; Regan, S P; Scott, H A; Sio, H; Spears, B K; Weber, C R

2016-11-01

The electron temperature at stagnation of an ICF implosion can be measured from the emission spectrum of high-energy x-rays that pass through the cold material surrounding the hot stagnating core. Here we describe a platform developed on the National Ignition Facility where trace levels of a mid-Z dopant (krypton) are added to the fuel gas of a symcap (symmetry surrogate) implosion to allow for the use of x-ray spectroscopy of the krypton line emission.

Experimental investigation of bright spots in broadband, gated x-ray images of ignition-scale implosions on the National Ignition Facility

International Nuclear Information System (INIS)

Barrios, M. A.; Suter, L. J.; Glenn, S.; Benedetti, L. R.; Bradley, D. K.; Collins, G. W.; Hammel, B. A.; Izumi, N.; Ma, T.; Scott, H.; Smalyuk, V. A.; Regan, S. P.; Epstein, R.; Kyrala, G. A.

2013-01-01

Bright spots in the hot spot intensity profile of gated x-ray images of ignition-scale implosions at the National Ignition Facility [G. H. Miller et al., Opt. Eng. 443, (2004)] are observed. X-ray images of cryogenically layered deuterium-tritium (DT) and tritium-hydrogen-deuterium (THD) ice capsules, and gas filled plastic shell capsules (Symcap) were recorded along the hohlraum symmetry axis. Heterogeneous mixing of ablator material and fuel into the hot spot (i.e., hot-spot mix) by hydrodynamic instabilities causes the bright spots. Hot-spot mix increases the radiative cooling of the hot spot. Fourier analysis of the x-ray images is used to quantify the evolution of bright spots in both x- and k-space. Bright spot images were azimuthally binned to characterize bright spot location relative to known isolated defects on the capsule surface. A strong correlation is observed between bright spot location and the fill tube for both Symcap and cryogenically layered DT and THD ice targets, indicating the fill tube is a significant seed for the ablation front instability causing hot-spot mix. The fill tube is the predominant seed for Symcaps, while other capsule non-uniformities are dominant seeds for the cryogenically layered DT and THD ice targets. A comparison of the bright spot power observed for Si- and Ge-doped ablator targets shows heterogeneous mix in Symcap targets is mostly material from the doped ablator layer

Increasing Z-pinch vacuum hohlraum capsule coupling efficiency

International Nuclear Information System (INIS)

Callahan, Debbie; Vesey, Roger Alan; Cochrane, Kyle Robert; Nikroo, A.; Bennett, Guy R.; Schroen, Diana Grace; Ruggles, Laurence E.; Porter, John L.; Streit, Jon; Mehlhorn, Thomas Alan; Cuneo, Michael Edward

2004-01-01

Symmetric capsule implosions in the double-ended vacuum hohlraum (DEH) on Z have demonstrated convergence ratios of 14-21 for 2.15-mm plastic ablator capsules absorbing 5-7 kJ of x-rays, based on backlit images of the compressed ablator remaining at peak convergence (1). Experiments with DD-filled 3.3-mm diameter capsules designed to absorb 14 kJ of x-rays have begun as an integrated test of drive temperature and symmetry, complementary to thin-shell symmetry diagnostic capsules. These capsule implosions are characterized by excellent control of symmetry (< 3% time-integrated), but low hohlraum efficiency (< 2%). Possible methods to increase the capsule absorbed energy in the DEH include mixed-component hohlraums, large diameter foam ablator capsules, transmissive shine shields between the z-pinch and capsule, higher spoke electrode x-ray transmission, a double-sided power feed, and smaller initial radius z-pinch wire arrays. Simulations will explore the potential for each of these modifications to increase the capsule coupling efficiency for near-term experiments on Z and ZR

Cryogenic tritium-hydrogen-deuterium and deuterium-tritium layer implosions with high density carbon ablators in near-vacuum hohlraums

International Nuclear Information System (INIS)

Meezan, N. B.; Hopkins, L. F. Berzak; Pape, S. Le; Divol, L.; MacKinnon, A. J.; Döppner, T.; Ho, D. D.; Jones, O. S.; Khan, S. F.; Ma, T.; Milovich, J. L.; Pak, A. E.; Ross, J. S.; Thomas, C. A.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Field, J. E.; Haan, S. W.

2015-01-01

High Density Carbon (or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a deuterium-tritium (DT) layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a tritium-hydrogen-deuterium (THD) layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 × 10 15 neutrons, 40% of the 1D simulated yield

Cryogenic tritium-hydrogen-deuterium and deuterium-tritium layer implosions with high density carbon ablators in near-vacuum hohlraums

Energy Technology Data Exchange (ETDEWEB)

Meezan, N. B., E-mail: meezan1@llnl.gov; Hopkins, L. F. Berzak; Pape, S. Le; Divol, L.; MacKinnon, A. J.; Döppner, T.; Ho, D. D.; Jones, O. S.; Khan, S. F.; Ma, T.; Milovich, J. L.; Pak, A. E.; Ross, J. S.; Thomas, C. A.; Benedetti, L. R.; Bradley, D. K.; Celliers, P. M.; Clark, D. S.; Field, J. E.; Haan, S. W. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); and others

2015-06-15

High Density Carbon (or diamond) is a promising ablator material for use in near-vacuum hohlraums, as its high density allows for ignition designs with laser pulse durations of <10 ns. A series of Inertial Confinement Fusion (ICF) experiments in 2013 on the National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a deuterium-tritium (DT) layered implosion driven by a 6.8 ns, 2-shock laser pulse. This paper describes these experiments and comparisons with ICF design code simulations. Backlit radiography of a tritium-hydrogen-deuterium (THD) layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightly oblate hot spot shape. Other diagnostics suggested an asymmetric compressed fuel layer. A streak camera-based hot spot self-emission diagnostic (SPIDER) showed a double-peaked history of the capsule self-emission. Simulations suggest that this is a signature of low quality hot spot formation. Changes to the laser pulse and pointing for a subsequent DT implosion resulted in a higher temperature, prolate hot spot and a thermonuclear yield of 1.8 × 10{sup 15} neutrons, 40% of the 1D simulated yield.

First liquid-layer implosion experiments at the NIF

Science.gov (United States)

Zylstra, Alex

2017-10-01

Replacing the standard ice layer in an ignition design with a liquid layer allows fielding the target with a higher central vapor pressure, leading to reduced implosion convergence ratio (CR). At lower CR, the implosions are expected to be more robust to instabilities and asymmetries than standard ice-layer designs, and are also unique in that the hot spot can be primarily formed from material originating in the central fuel vapor. The first liquid-layer implosions on the National Ignition Facility (NIF) have been performed by wicking the liquid fuel into a supporting foam that lines the inside surface of the capsule. A series of shots has been conducted between CR of 12 and 20 using a HDC ablator driven by a 3-shock pulse in a near-vacuum Au hohlraum. At the lowest CR the implosion performance is well predicted by 2-D radiation-hydrodynamics calculations. However, as the CR is increased the nominal simulations do not capture the experimentally observed trends. Data-based models suggest that the hot spot formation is unexpectedly suppressed at higher convergence. The data could be explained by reduced hydrodynamic coupling efficiency, or an anomalously enhanced thermal conductivity in the mixed DT/foam material. We show that the latter hypothesis can explain observed trends in several experimental metrics, including the yield, ion temperature, and burn duration. This work was performed under the auspices of the U.S. DoE by LANL under contract DE-AC52-06NA52396.

A technique for extending by ∼10{sup 3} the dynamic range of compact proton spectrometers for diagnosing ICF implosions on the National Ignition Facility and OMEGA

Energy Technology Data Exchange (ETDEWEB)

Sio, H., E-mail: hsio@mit.edu; Séguin, F. H.; Frenje, J. A.; Gatu Johnson, M.; Zylstra, A. B.; Rinderknecht, H. G.; Rosenberg, M. J.; Li, C. K.; Petrasso, R. D. [Massachusetts Institute of Technology Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

2014-11-15

Wedge Range Filter (WRF) proton spectrometers are routinely used on OMEGA and the NIF for diagnosing ρR and ρR asymmetries in direct- and indirect-drive implosions of D{sup 3}He-, D{sub 2}-, and DT-gas-filled capsules. By measuring the optical opacity distribution in CR-39 due to proton tracks in high-yield applications, as opposed to counting individual tracks, WRF dynamic range can be extended by 10{sup 2} for obtaining the spectral shape, and by 10{sup 3} for mean energy (ρR) measurement, corresponding to proton fluences of 10{sup 8} and 10{sup 9} cm{sup −2}, respectively. Using this new technique, ρR asymmetries can be measured during both shock and compression burn (proton yield ∼10{sup 8} and ∼10{sup 12}, respectively) in 2-shock National Ignition Facility implosions with the standard WRF accuracy of ±∼10 mg/cm{sup 2}.

Effects of the P2 M-band flux asymmetry of laser-driven gold Hohlraums on the implosion of ICF ignition capsule

Science.gov (United States)

Li, Yongsheng; Gu, Jianfa; Wu, Changshu; Song, Peng; Dai, Zhensheng; Li, Shuanggui; Li, Xin; Kang, Dongguo; Gu, Peijun; Zheng, Wudi; Zou, Shiyang; Ding, Yongkun; Lan, Ke; Ye, Wenhua; Zhang, Weiyan

2016-07-01

Low-mode asymmetries in the laser-indirect-drive inertial confinement fusion implosion experiments conducted on the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] are deemed the main obstacles hindering further improvement of the nuclear performance of deuterium-tritium-layered capsules. The dominant seeds of these asymmetries include the P2 and P4 asymmetries of x-ray drives and P2 asymmetry introduced by the supporting "tent." Here, we explore the effects of another possible seed that can lead to low-mode asymmetric implosions, i.e., the M-band flux asymmetry (MFA) in laser-driven cylindrical gold Hohlraums. It is shown that the M-band flux facilitates the ablation and acceleration of the shell, and that positive P2 MFAs can result in negative P2 asymmetries of hot spots and positive P2 asymmetries of shell's ρR. An oblate or toroidal hot spot, depending on the P2 amplitude of MFA, forms at stagnation. The energy loss of such a hot spot via electron thermal conduction is seriously aggravated not only due to the enlarged hot spot surface but also due to the vortices that develop and help transferring thermal energy from the hotter center to the colder margin of such a hot spot. The cliffs of nuclear performance for the two methodologies of applying MFA (i.e., symmetric flux in the presence of MFA and MFA added for symmetric soft x-ray flux) are obtained locating at 9.5% and 5.0% of P2/P0 amplitudes, respectively.

Effects of the P2 M-band flux asymmetry of laser-driven gold Hohlraums on the implosion of ICF ignition capsule

Energy Technology Data Exchange (ETDEWEB)

Li, Yongsheng [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Graduate School, China Academy of Engineering Physics, Beijing 100088 (China); Gu, Jianfa; Wu, Changshu; Song, Peng; Dai, Zhensheng; Li, Shuanggui; Li, Xin; Kang, Dongguo; Gu, Peijun; Zheng, Wudi; Zou, Shiyang [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Ding, Yongkun [Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Lan, Ke; Ye, Wenhua, E-mail: ye-wenhua@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zhang, Weiyan [China Academy of Engineering Physics, Mianyang 621900 (China)

2016-07-15

Low-mode asymmetries in the laser-indirect-drive inertial confinement fusion implosion experiments conducted on the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] are deemed the main obstacles hindering further improvement of the nuclear performance of deuterium-tritium-layered capsules. The dominant seeds of these asymmetries include the P2 and P4 asymmetries of x-ray drives and P2 asymmetry introduced by the supporting “tent.” Here, we explore the effects of another possible seed that can lead to low-mode asymmetric implosions, i.e., the M-band flux asymmetry (MFA) in laser-driven cylindrical gold Hohlraums. It is shown that the M-band flux facilitates the ablation and acceleration of the shell, and that positive P2 MFAs can result in negative P2 asymmetries of hot spots and positive P2 asymmetries of shell's ρR. An oblate or toroidal hot spot, depending on the P2 amplitude of MFA, forms at stagnation. The energy loss of such a hot spot via electron thermal conduction is seriously aggravated not only due to the enlarged hot spot surface but also due to the vortices that develop and help transferring thermal energy from the hotter center to the colder margin of such a hot spot. The cliffs of nuclear performance for the two methodologies of applying MFA (i.e., symmetric flux in the presence of MFA and MFA added for symmetric soft x-ray flux) are obtained locating at 9.5% and 5.0% of P2/P0 amplitudes, respectively.

Effects of the P2 M-band flux asymmetry of laser-driven gold Hohlraums on the implosion of ICF ignition capsule

International Nuclear Information System (INIS)

Li, Yongsheng; Gu, Jianfa; Wu, Changshu; Song, Peng; Dai, Zhensheng; Li, Shuanggui; Li, Xin; Kang, Dongguo; Gu, Peijun; Zheng, Wudi; Zou, Shiyang; Ding, Yongkun; Lan, Ke; Ye, Wenhua; Zhang, Weiyan

2016-01-01

Low-mode asymmetries in the laser-indirect-drive inertial confinement fusion implosion experiments conducted on the National Ignition Facility [G. H. Miller et al., Nucl. Fusion 44, S228 (2004)] are deemed the main obstacles hindering further improvement of the nuclear performance of deuterium-tritium-layered capsules. The dominant seeds of these asymmetries include the P2 and P4 asymmetries of x-ray drives and P2 asymmetry introduced by the supporting “tent.” Here, we explore the effects of another possible seed that can lead to low-mode asymmetric implosions, i.e., the M-band flux asymmetry (MFA) in laser-driven cylindrical gold Hohlraums. It is shown that the M-band flux facilitates the ablation and acceleration of the shell, and that positive P2 MFAs can result in negative P2 asymmetries of hot spots and positive P2 asymmetries of shell's ρR. An oblate or toroidal hot spot, depending on the P2 amplitude of MFA, forms at stagnation. The energy loss of such a hot spot via electron thermal conduction is seriously aggravated not only due to the enlarged hot spot surface but also due to the vortices that develop and help transferring thermal energy from the hotter center to the colder margin of such a hot spot. The cliffs of nuclear performance for the two methodologies of applying MFA (i.e., symmetric flux in the presence of MFA and MFA added for symmetric soft x-ray flux) are obtained locating at 9.5% and 5.0% of P2/P0 amplitudes, respectively.

Progress Toward Ignition on the National Ignition Facility

International Nuclear Information System (INIS)

Kauffman, R.L.

2011-01-01

The principal approach to ignition on the National Ignition Facility (NIF) is indirect drive. A schematic of an ignition target is shown in Figure 1. The laser beams are focused through laser entrance holes at each end of a high-Z cylindrical case, or hohlraum. The lasers irradiate the hohlraum walls producing x-rays that ablate and compress the fuel capsule in the center of the hohlraum. The hohlraum is made of Au, U, or other high-Z material. For ignition targets, the hohlraum is ∼0.5 cm diameter by ∼1 cm in length. The hohlraum absorbs the incident laser energy producing x-rays for symmetrically imploding the capsule. The fuel capsule is a ∼2-mm-diameter spherical shell of CH, Be, or C filled with DT fuel. The DT fuel is in the form of a cryogenic layer on the inside of the capsule. X-rays ablate the outside of the capsule, producing a spherical implosion. The imploding shell stagnates in the center, igniting the DT fuel. NIC has overseen installation of all of the hardware for performing ignition experiments, including commissioning of approximately 50 diagnostic systems in NIF. The diagnostics measure scattered optical light, x-rays from the hohlraum over the energy range from 100 eV to 500 keV, and x-rays, neutrons, and charged particles from the implosion. An example of a diagnostic is the Magnetic Recoil Spectrometer (MRS) built by a collaboration of scientists from MIT, UR-LLE, and LLNL shown in Figure 2. MRS measures the neutron spectrum from the implosion, providing information on the neutron yield and areal density that are metrics of the quality of the implosion. Experiments on NIF extend ICF research to unexplored regimes in target physics. NIF can produce more than 50 times the laser energy and more than 20 times the power of any previous ICF facility. Ignition scale hohlraum targets are three to four times larger than targets used at smaller facilities, and the ignition drive pulses are two to five times longer. The larger targets and longer

Resolving a central ICF issue for ignition: Implosion symmertry

International Nuclear Information System (INIS)

Cray, M.; Delamater, N.D.; Fernandez, J.C.

1994-01-01

The Los Alamos National Laboratory Inertial Confinement Fusion (ICF) Program focuses on resolving key target-physics issues and developing technology needed for the National Ignition Facility (NIF). This work is being performed in collaboration with Lawrence Livermore National Laboratory (LLNL). A major requirement for the indirect-drive NIF ignition target is to achieve the irradiation uniformity on the capsule surface needed for a symmetrical high-convergence implosion. Los Alamos employed an integrated modeling technique using the Lasnex radiation-hydrodynamics code to design two different targets that achieve ignition and moderate gain. Los Alamos is performing experiments on the Nova Laser at LLNL in order to validate our NIF ignition calculations

First shock tuning and backscatter measurements for large case-to-capsule ratio beryllium targets

Science.gov (United States)

Loomis, Eric; Yi, Austin; Kline, John; Kyrala, George; Simakov, Andrei; Wilson, Doug; Ralph, Joe; Dewald, Eduard; Strozzi, David; Celliers, Peter; Millot, Marius; Tommasini, Riccardo

2016-10-01

The current under performance of target implosions on the National Ignition Facility (NIF) has necessitated scaling back from high convergence ratio to access regimes of reduced physics uncertainties. These regimes, we expect, are more predictable by existing radiation hydrodynamics codes giving us a better starting point for isolating key physics questions. One key question is the lack of predictable in-flight and hot spot shape due to a complex hohlraum radiation environment. To achieve more predictable, shape tunable implosions we have designed and fielded a large 4.2 case-to-capsule ratio (CCR) target at the NIF using 6.72 mm diameter Au hohlraums and 1.6 mm diameter Cu-doped Be capsules. Simulations show that at these dimensions during a 10 ns 3-shock laser pulse reaching 270 eV hohlraum temperatures, the interaction between hohlraum and capsule plasma, which at lower CCR lead to beam propagation impedance by artificial plasma stagnation, are reduced. In this talk we will present measurements of early time drive symmetry using two-axis line-imaging velocimetry (VISAR) and streaked radiography measuring velocity of the imploding shell and their comparisons to post-shot calculations using the code HYDRA (Lawrence Livermore National Laboratory).

Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums

Science.gov (United States)

Dewald, E. L.; Hartemann, F.; Michel, P.; Milovich, J.; Hohenberger, M.; Pak, A.; Landen, O. L.; Divol, L.; Robey, H. F.; Hurricane, O. A.; Döppner, T.; Albert, F.; Bachmann, B.; Meezan, N. B.; MacKinnon, A. J.; Callahan, D.; Edwards, M. J.

2016-02-01

In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10 × higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.

Main drive optimization of a high-foot pulse shape in inertial confinement fusion implosions

Science.gov (United States)

Wang, L. F.; Ye, W. H.; Wu, J. F.; Liu, Jie; Zhang, W. Y.; He, X. T.

2016-12-01

While progress towards hot-spot ignition has been made achieving an alpha-heating dominated state in high-foot implosion experiments [Hurricane et al., Nat. Phys. 12, 800 (2016)] on the National Ignition Facility, improvements are needed to increase the fuel compression for the enhancement of the neutron yield. A strategy is proposed to improve the fuel compression through the recompression of a shock/compression wave generated by the end of the main drive portion of a high-foot pulse shape. Two methods for the peak pulse recompression, namely, the decompression-and-recompression (DR) and simple recompression schemes, are investigated and compared. Radiation hydrodynamic simulations confirm that the peak pulse recompression can clearly improve fuel compression without significantly compromising the implosion stability. In particular, when the convergent DR shock is tuned to encounter the divergent shock from the capsule center at a suitable position, not only the neutron yield but also the stability of stagnating hot-spot can be noticeably improved, compared to the conventional high-foot implosions [Hurricane et al., Phys. Plasmas 21, 056314 (2014)].

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

Directory of Open Access Journals (Sweden)

Robey H.F.

2013-11-01

Full Text Available 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.

Onset of hydrodynamic mix in high-velocity, highly compressed inertial confinement fusion implosions.

Science.gov (United States)

Ma, T; Patel, P K; Izumi, N; Springer, P T; Key, M H; Atherton, L J; Benedetti, L R; Bradley, D K; Callahan, D A; Celliers, P M; Cerjan, C J; Clark, D S; Dewald, E L; Dixit, S N; Döppner, T; Edgell, D H; Epstein, R; Glenn, S; Grim, G; Haan, S W; Hammel, B A; Hicks, D; Hsing, W W; Jones, O S; Khan, S F; Kilkenny, J D; Kline, J L; Kyrala, G A; Landen, O L; Le Pape, S; MacGowan, B J; Mackinnon, A J; MacPhee, A G; Meezan, N B; Moody, J D; Pak, A; Parham, T; Park, H-S; Ralph, J E; Regan, S P; Remington, B A; Robey, H F; Ross, J S; Spears, B K; Smalyuk, V; Suter, L J; Tommasini, R; Town, R P; Weber, S V; Lindl, J D; Edwards, M J; Glenzer, S H; Moses, E I

2013-08-23

Deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility have demonstrated yields ranging from 0.8 to 7×10(14), and record fuel areal densities of 0.7 to 1.3 g/cm2. These implosions use hohlraums irradiated with shaped laser pulses of 1.5-1.9 MJ energy. The laser peak power and duration at peak power were varied, as were the capsule ablator dopant concentrations and shell thicknesses. We quantify the level of hydrodynamic instability mix of the ablator into the hot spot from the measured elevated absolute x-ray emission of the hot spot. We observe that DT neutron yield and ion temperature decrease abruptly as the hot spot mix mass increases above several hundred ng. The comparison with radiation-hydrodynamic modeling indicates that low mode asymmetries and increased ablator surface perturbations may be responsible for the current performance.

Reconstruction of 2D x-ray radiographs at the National Ignition Facility using pinhole tomography (invited)

Energy Technology Data Exchange (ETDEWEB)

Field, J. E., E-mail: field9@llnl.gov; Rygg, J. R.; Barrios, M. A.; Benedetti, L. R.; Döppner, T.; Izumi, N.; Jones, O.; Khan, S. F.; Ma, T.; Nagel, S. R.; Pak, A.; Tommasini, R.; Bradley, D. K.; Town, R. P. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2014-11-15

Two-dimensional radiographs of imploding fusion capsules are obtained at the National Ignition Facility by projection through a pinhole array onto a time-gated framing camera. Parallax among images in the image array makes it possible to distinguish contributions from the capsule and from the backlighter, permitting correction of backlighter non-uniformities within the capsule radiograph. Furthermore, precise determination of the imaging system geometry and implosion velocity enables combination of multiple images to reduce signal-to-noise and discover new capsule features.

Three-dimensional simulations of National Ignition Facility implosions: Insight into experimental observables

International Nuclear Information System (INIS)

Spears, Brian K.; Munro, David H.; Sepke, Scott; Caggiano, Joseph; Clark, Daniel; Hatarik, Robert; Kritcher, Andrea; Sayre, Daniel; Yeamans, Charles; Knauer, James; Hilsabeck, Terry; Kilkenny, Joe

2015-01-01

We simulate in 3D both the hydrodynamics and, simultaneously, the X-ray and neutron diagnostic signatures of National Ignition Facility (NIF) implosions. We apply asymmetric radiation drive to study the impact of low mode asymmetry on diagnostic observables. We examine X-ray and neutron images as well as neutron spectra for these perturbed implosions. The X-ray images show hot spot evolution on small length scales and short time scales, reflecting the incomplete stagnation seen in the simulation. The neutron images show surprising differences from the X-ray images. The neutron spectra provide additional measures of implosion asymmetry. Flow in the hot spot alters the neutron spectral peak, namely, the peak location and width. The changes in the width lead to a variation in the apparent temperature with viewing angle that signals underlying hot spot asymmetry. We compare our new expectations based on the simulated data with NIF data. We find that some recent cryogenic layered experiments show appreciable temperature anisotropy indicating residual flow in the hot spot. We also find some trends in the data that do not reflect our simulation and theoretical understanding

Three-dimensional simulations of National Ignition Facility implosions: Insight into experimental observables

Energy Technology Data Exchange (ETDEWEB)

Spears, Brian K., E-mail: spears9@llnl.gov; Munro, David H.; Sepke, Scott; Caggiano, Joseph; Clark, Daniel; Hatarik, Robert; Kritcher, Andrea; Sayre, Daniel; Yeamans, Charles [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Knauer, James [Laboratory for Laser Energetics, 250 E. River Road, Rochester, New York 14623-1212 (United States); Hilsabeck, Terry; Kilkenny, Joe [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)

2015-05-15

We simulate in 3D both the hydrodynamics and, simultaneously, the X-ray and neutron diagnostic signatures of National Ignition Facility (NIF) implosions. We apply asymmetric radiation drive to study the impact of low mode asymmetry on diagnostic observables. We examine X-ray and neutron images as well as neutron spectra for these perturbed implosions. The X-ray images show hot spot evolution on small length scales and short time scales, reflecting the incomplete stagnation seen in the simulation. The neutron images show surprising differences from the X-ray images. The neutron spectra provide additional measures of implosion asymmetry. Flow in the hot spot alters the neutron spectral peak, namely, the peak location and width. The changes in the width lead to a variation in the apparent temperature with viewing angle that signals underlying hot spot asymmetry. We compare our new expectations based on the simulated data with NIF data. We find that some recent cryogenic layered experiments show appreciable temperature anisotropy indicating residual flow in the hot spot. We also find some trends in the data that do not reflect our simulation and theoretical understanding.

Improved Understanding of Implosion Symmetry through New Experimental Techniques Connecting Hohlraum Dynamics with Laser Beam Deposition

Science.gov (United States)

Ralph, Joseph; Salmonson, Jay; Dewald, Eduard; Bachmann, Benjamin; Edwards, John; Graziani, Frank; Hurricane, Omar; Landen, Otto; Ma, Tammy; Masse, Laurent; MacLaren, Stephen; Meezan, Nathan; Moody, John; Parrilla, Nicholas; Pino, Jesse; Sacks, Ryan; Tipton, Robert

2017-10-01

Understanding what affects implosion symmetry has been a challenge for scientists designing indirect drive inertial confinement fusion experiments on the National Ignition Facility (NIF). New experimental techniques and data analysis have been employed aimed at improving our understanding of the relationship between hohlraum dynamics and implosion symmetry. Thin wall imaging data allows for time-resolved imaging of 10 keV Au l-band x-rays providing for the first time on the NIF, a spatially resolved measurement of laser deposition with time. In the work described here, we combine measurements from the thin wall imaging with time resolved views of the interior of the hohlraum. The measurements presented are compared to hydrodynamic simulations as well as simplified physics models. The goal of this work is to form a physical picture that better explains the relationship of the hohlraum dynamics and capsule ablator on laser beam propagation and implosion symmetry. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Rugby and elliptical-shaped hohlraums experiments on the OMEGA laser facility

Science.gov (United States)

Tassin, Veronique; Monteil, Marie-Christine; Depierreux, Sylvie; Masson-Laborde, Paul-Edouard; Philippe, Franck; Seytor, Patricia; Fremerye, Pascale; Villette, Bruno

2017-10-01

We are pursuing on the OMEGA laser facility indirect drive implosions experiments in gas-filled rugby-shaped hohlraums in preparation for implosion plateforms on LMJ. The question of the precise wall shape of rugby hohlraum has been addressed as part of future megajoule-scale ignition designs. Calculations show that elliptical-shaped holhraum is more efficient than spherical-shaped hohlraum. There is less wall hydrodynamics and less absorption for the inner cone, provided a better control of time-dependent symmetry swings. In this context, we have conducted a series of experiments on the OMEGA laser facility. The goal of these experiments was therefore to characterize energetics with a complete set of laser-plasma interaction measurements and capsule implosion in gas-filled elliptical-shaped hohlraum with comparison with spherical-shaped hohlraum. Experiments results are discussed and compared to FCI2 radiation hydrodynamics simulations.

Comparing neutron and X-ray images from NIF implosions

Directory of Open Access Journals (Sweden)

Wilson D.C.

2013-11-01

Full Text Available Directly laser driven and X-radiation driven DT filled capsules differ in the relationship between neutron and X-ray images. Shot N110217, a directly driven DT-filled glass micro-balloon provided the first neutron images at the National Ignition Facility. As seen in implosions on the Omega laser, the neutron image can be enclosed inside time integrated X-ray images. HYDRA simulations show the X-ray image is dominated by emission from the hot glass shell while the neutron image arises from the DT fuel it encloses. In the absence of mix or jetting, X-ray images of a cryogenically layered THD fuel capsule should be dominated by emission from the hydrogen rather than the cooler plastic shell that is separated from the hot core by cold DT fuel. This cool, dense DT, invisible in X-ray emission, shows itself by scattering hot core neutrons. Germanium X-ray emission spectra and Ross pair filtered X-ray energy resolved images suggest that germanium doped plastic emits in the torus shaped hot spot, probably reducing the neutron yield.

Seismic analysis for shroud facility in-pile tube and saturated temperature capsules

International Nuclear Information System (INIS)

Iimura, Koichi; Yamaura, Takayuki; Ogawa, Mitsuhiro

2009-07-01

At Oarai Research and Development Center, Japan Atomic Energy Agency (JAEA), the plan of repairing and refurbishing Japan Materials Testing Reactor (JMTR) has progressed in order to restart JMTR operation in the fiscal 2011. As a part of effective use of JMTR, the neutron irradiation tests of LWR fuels and materials has been planned in order to study their soundness. By using Oarai Shroud Facility (OSF-1) and Fuel Irradiation Facility with the He-3 gas control system for power lamping test using Boiling Water Capsules (BOCA Irradiation Facility), the irradiation tests with power ramping will be carried out to study the soundness of fuel under LWR Transient condition. OSF-1 is the irradiation facility of shroud type that can insert and eject the capsule under reactor operation, and is composed of 'In-pile Tube', 'Cooling system' and 'Capsule exchange system'. BOCA Irradiation Facility is the facility which simulates irradiation environment of LWR, and is composed of 'Boiling water Capsule', 'Capsule control system' and 'Power control system by He-3'. By using Saturated temperature Capsules and the water environment control system, the material irradiation tests under the water chemistry condition of LWR will be carried out to clarify the mechanism of IASCC. In JMTR, these facilities are in service at the present. However, the detailed design for renewal or remodeling was carried out based on the new design condition in order to be correspondent to the irradiation test plan after restart JMTR operation. In this seismic analysis of the detailed design, each equipment classification and operating state were arranged with 'Japanese technical standards of the structure on nuclear facility for test research' and 'Technical guidelines for seismic design of nuclear power plants on current, and then, stress calculation and evaluation were carried out by FEM piping analysis code 'SAP' and structure analysis code 'ABAQUS'. About the stress of the seismic force, it was proven

The effect of laser spot shapes on polar-direct-drive implosions on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Weilacher, F.; Radha, P. B., E-mail: rbah@lle.rochester.edu; Collins, T. J. B.; Marozas, J. A. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States)

2015-03-15

Ongoing polar-direct-drive (PDD) implosions on the National Ignition Facility (NIF) [J. D. Lindl and E. I. Moses, Phys. Plasmas 18, 050901 (2011)] use existing NIF hardware, including indirect-drive phase plates. This limits the performance achievable in these implosions. Spot shapes are identified that significantly improve the uniformity of PDD NIF implosions; outer surface deviation is reduced by a factor of 7 at the end of the laser pulse and hot-spot distortion is reduced by a factor of 2 when the shell has converged by a factor of ∼10. As a result, the neutron yield increases by approximately a factor of 2. This set of laser spot shapes is a combination of circular and elliptical spots, along with elliptical spot shapes modulated by an additional higher-intensity ellipse offset from the center of the beam. This combination is motivated in this paper. It is also found that this improved implosion uniformity is obtained independent of the heat conduction model. This work indicates that significant improvement in performance can be obtained robustly with the proposed spot shapes.

The effect of laser spot shapes on polar-direct-drive implosions on the National Ignition Facility

International Nuclear Information System (INIS)

Weilacher, F.; Radha, P. B.; Collins, T. J. B.; Marozas, J. A.

2015-01-01

Ongoing polar-direct-drive (PDD) implosions on the National Ignition Facility (NIF) [J. D. Lindl and E. I. Moses, Phys. Plasmas 18, 050901 (2011)] use existing NIF hardware, including indirect-drive phase plates. This limits the performance achievable in these implosions. Spot shapes are identified that significantly improve the uniformity of PDD NIF implosions; outer surface deviation is reduced by a factor of 7 at the end of the laser pulse and hot-spot distortion is reduced by a factor of 2 when the shell has converged by a factor of ∼10. As a result, the neutron yield increases by approximately a factor of 2. This set of laser spot shapes is a combination of circular and elliptical spots, along with elliptical spot shapes modulated by an additional higher-intensity ellipse offset from the center of the beam. This combination is motivated in this paper. It is also found that this improved implosion uniformity is obtained independent of the heat conduction model. This work indicates that significant improvement in performance can be obtained robustly with the proposed spot shapes

Recent experimental results on ICF target implosions by Z-pinch radiation sources and their relevance to ICF ignition studies

International Nuclear Information System (INIS)

Mehlhorn, T A; Bailey, J E; Bennett, G; Chandler, G A; Cooper, G; Cuneo, M E; Golovkin, I; Hanson, D L; Leeper, R J; MacFarlane, J J; Mancini, R C; Matzen, M K; Nash, T J; Olson, C L; Porter, J L; Ruiz, C L; Schroen, D G; Slutz, S A; Varnum, W; Vesey, R A

2003-01-01

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ∼220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6±1.3) x 10 10 . Argon spectra confirm a hot fuel with T e ∼ 1 keV and n e ∼ (1-2) x 10 23 cm -3 . Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ∼70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P 2 radiation asymmetries to ±2%. Hemispherical capsule implosions have also been radiographed in Z in preparation for future experiments in fast ignition physics. Z-pinch-driven inertial fusion energy concepts are being developed. The refurbished Z machine (ZR) will begin providing scaling information on capsule and Z-pinch in 2006. The addition of a short pulse capability to ZBL will enable research into fast ignition physics in the combination of ZR and ZBL-petawatt. ZR could provide a test bed to study NIF-relevant double-shell ignition concepts using dynamic hohlraums and advanced symmetry control techniques in the double-pinch hohlraum backlit by ZBL

Recent experimental results on ICF target implosions by Z-pinch radiation sources and their relevance to ICF ignition studies

International Nuclear Information System (INIS)

Bailey, James E.; Chandler, Gordon Andrew; Vesey, Roger Alan; Hanson, David Lester; Olson, Craig Lee; Nash, Thomas J.; Matzen, Maurice Keith; Ruiz, Carlos L.; Porter, John Larry Jr.; Cuneo, Michael Edward; Varnum, William S.; Bennett, Guy R.; Cooper, Gary Wayne; Schroen, Diana Grace; Slutz, Stephen A.; MacFarlane, Joseph John; Leeper, Ramon Joe; Golovkin, I.E.; Mehlhorn, Thomas Alan; Mancini, Roberto Claudio

2003-01-01

Inertial confinement fusion capsule implosions absorbing up to 35 kJ of x-rays from a ∼220 eV dynamic hohlraum on the Z accelerator at Sandia National Laboratories have produced thermonuclear D-D neutron yields of (2.6 ± 1.3) x 10 10 . Argon spectra confirm a hot fuel with Te ∼ 1 keV and n e ∼ (1-2) x 10 23 cm -3 . Higher performance implosions will require radiation symmetry control improvements. Capsule implosions in a ∼70 eV double-Z-pinch-driven secondary hohlraum have been radiographed by 6.7 keV x-rays produced by the Z-beamlet laser (ZBL), demonstrating a drive symmetry of about 3% and control of P 2 radiation asymmetries to ±2%. Hemispherical capsule implosions have also been radiographed in Z in preparation for future experiments in fast ignition physics. Z-pinch-driven inertial fusion energy concepts are being developed. The refurbished Z machine (ZR) will begin providing scaling information on capsule and Z-pinch in 2006. The addition of a short pulse capability to ZBL will enable research into fast ignition physics in the combination of ZR and ZBL-petawatt. ZR could provide a test bed to study NIF-relevant double-shell ignition concepts using dynamic hohlraums and advanced symmetry control techniques in the double-pinch hohlraum backlit by ZBL.

Return of isotope capsules to the Waste Encapsulation and Storage Facility

International Nuclear Information System (INIS)

1994-05-01

Cesium-137 and strontium-90 isotopes were removed from Hanford Site high-level tank wastes, and were encapsulated at the Hanford Site's Waste Encapsulation and Storage Facility (WESF), beginning in 1974. Over the past several years, radioactive isotope capsules have been sent to other U.S. Department of Energy (DOE)-controlled sites to be used for research and development applications, as well as leased to a number of commercial facilities for commercial applications (e.g., sterilization of medical supplies). Due to uncertainty regarding the cause of the release of a small quantity of cesium-137 to an isolated water basin from a WESF cesium-137 capsule in a commercial facility in Decatur, Georgia, the DOE has determined that it needs to return leased capsules from IOTECH, Incorporated (IOTECH), Northglenn, Colorado; Pacific Northwest Laboratory (PNL), Richland, Washington; and the Applied Radiant Energy Corporation (ARECO), Lynchburg, Virginia; to the WESF Facility on the Hanford Site, to ensure safe management and storage, pending final disposition. All of these capsules located at the commercial facilities were successfully tested during Calendar Year 1993, and none showed any indication of off-normal specifications. Storage at the WESF will continue under the actions selected in the Record of Decision for the Final Environmental Impact Statement: Disposal of Hanford Defense High-Level, Transuranic and Tank Wastes, Hanford Site, Richland, Washington

ALARA implementation in 131I therapeutic capsule production facility

International Nuclear Information System (INIS)

Kumawat, Lalit; Swaminathan, N.; Sudheer, T.S.; Sachdev, S.S.; Arora, S.S.; Vairalkar, K.G.

2005-01-01

Sodium iodide 131 I solution had been invariably administered to patients for both diagnosis and therapy of thyrotoxicosis. The undue exposure to non-target organs has been over come by introducing NaI ( 131 I) in a gelatin capsule. BRIT has set up experimental facility for the preparation and the production volume has augmented into four fold due to increase in demand and the same facility is being used to cater the need. However, the adequately shielded facility (fume hood) used for (manual) dispensing activity in capsules, capsules and product vial capping, transfer of the vials into lead pots and activity measurement of each vial has resulted in significant increase in the personnel exposure. The sources had been identified and efforts were made to reduce the exposure in these operations. An annular shield was introduced around the dispenser, resulted in the reduction of radiation field at wrist level by a factor of three. Introduction of shielded automated dispenser and usage of longer tools for transfer and capping of vials has effected in two times reduction of collective wrist dose. Currently, the relocated capping station two meters away from the source certainly will bring down further exposure. (author)

Robustness studies of ignition targets for the National Ignition Facility in two dimensions

International Nuclear Information System (INIS)

Clark, Daniel S.; Haan, Steven W.; Salmonson, Jay D.

2008-01-01

Inertial confinement fusion capsules are critically dependent on the integrity of their hot spots to ignite. At the time of ignition, only a certain fractional perturbation of the nominally spherical hot spot boundary can be tolerated and the capsule still achieve ignition. The degree to which the expected hot spot perturbation in any given capsule design is less than this maximum tolerable perturbation is a measure of the ignition margin or robustness of that design. Moreover, since there will inevitably be uncertainties in the initial character and implosion dynamics of any given capsule, all of which can contribute to the eventual hot spot perturbation, quantifying the robustness of that capsule against a range of parameter variations is an important consideration in the capsule design. Here, the robustness of the 300 eV indirect drive target design for the National Ignition Facility [Lindl et al., Phys. Plasmas 11, 339 (2004)] is studied in the parameter space of inner ice roughness, implosion velocity, and capsule scale. A suite of 2000 two-dimensional simulations, run with the radiation hydrodynamics code LASNEX, is used as the data base for the study. For each scale, an ignition region in the two remaining variables is identified and the ignition cliff is mapped. In accordance with the theoretical arguments of Levedahl and Lindl [Nucl. Fusion 37, 165 (1997)] and Kishony and Shvarts [Phys. Plasmas 8, 4925 (2001)], the location of this cliff is fitted to a power law of the capsule implosion velocity and scale. It is found that the cliff can be quite well represented in this power law form, and, using this scaling law, an assessment of the overall (one- and two-dimensional) ignition margin of the design can be made. The effect on the ignition margin of an increase or decrease in the density of the target fill gas is also assessed

Optimizing implosion yields using rugby-shaped hohlraums

Science.gov (United States)

Park, Hye-Sook; Robey, H.; Amendt, P.; Philippe, F.; Casner, A.; Caillaud, T.; Bourgade, J.-L.; Landoas, O.; Li, C. K.; Petrasso, R.; Seguin, F.; Rosenberg, M.; Glebov, V. Yu.

2009-11-01

We present the first experimental results on optimizing capsule implosion experiments by using rugby-shaped hohlraums [1] on the Omega laser, University of Rochester. This campaign compared D2-filled capsule performance between standard cylindrical Au hohlraums and rugby-shaped hohlraums for demonstrating the energetics advantages of the rugby geometry. Not only did the rugby-shaped hohlraums show nearly 20% more x-ray drive energy over the cylindrical hohlraums, but also the high-performance design of the capsules provided nearly 20 times more DD neutrons than in any previous Omega hohlraum campaigns, thereby enabling use of neutron temporal diagnostics. Comparison with simulations on neutron burn histories, x-ray core imaging, backscattered laser light and radiation temperature are presented. [1] P. Amendt et al., Phys. Plasmas 15, 012702 (2008)

Physics of ignition for ICF capsules

International Nuclear Information System (INIS)

Lindl, J.D.

1989-01-01

The implosion of an ICF capsule must accomplish both compression of the main fuel to several hundred grams per cubic centimeter and heating and compression of the central region of the fuel to ignition. This report discusses the physics of these conditions

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

Directory of Open Access Journals (Sweden)

Guler Nevzat

2013-11-01

Full Text Available 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.

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

Science.gov (United States)

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.; Traille, Albert

2013-11-01

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.

High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Koch, J. A.; Stewart, R. E.; Beiersdorfer, P.; Shepherd, R.; Schneider, M. B.; Miles, A. R.; Scott, H. A.; Smalyuk, V. A.; Hsing, W. W. [Lawrence Livermore National Laboratory, P.O. Box 808, L-493, Livermore, California 94550 (United States)

2012-10-15

Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-{alpha} at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

A generalized scaling law for the ignition energy of inertial confinement fusion capsules

International Nuclear Information System (INIS)

Herrmann, M.C.

2001-01-01

The minimum energy needed to ignite an inertial confinement fusion capsule is of considerable interest in the optimization of an inertial fusion driver. Recent computational work investigating this minimum energy has found that it depends on the capsule implosion history, in particular, on the capsule drive pressure. This dependence is examined using a series of LASNEX simulations to find ignited capsules which have different values of the implosion velocity, fuel adiabat and drive pressure. It is found that the main effect of varying the drive pressure is to alter the stagnation of the capsule, changing its stagnation adiabat, which, in turn, affects the energy required for ignition. To account for this effect a generalized scaling law has been devised for the ignition energy, E ign ∝α if 1.88±0.05 υ -5.89±0.12 P -0.77±0.03 . This generalized scaling law agrees with the results of previous work in the appropriate limits. (author)

ARES Modeling of High-foot Implosions (NNSA Milestone #5466)

International Nuclear Information System (INIS)

Hurricane, O. A.

2016-01-01

ARES ''capsule only'' simulations demonstrated results of applying an ASC code to a suite of high-foot ICF implosion experiments. While a capability to apply an asymmetric FDS drive to the capsule-only model using add-on Python routines exists, it was not exercised here. The ARES simulation results resemble the results from HYDRA simulations documented in A. Kritcher, et al., Phys. Plasmas, 23, 052709 (2016); namely, 1D simulation and data are in reasonable agreement for the lowest velocity experiments, but diverge from each other at higher velocities.

Diagnosing implosion performance at the National Ignition Facility (NIF) by means of neutron spectrometry

International Nuclear Information System (INIS)

Frenje, J.A.; Casey, D.T.; Johnson, M. Gatu; Bionta, R.; Bond, E.J.; Caggiano, J.A.; Cerjan, C.; Edwards, J.; Eckart, M.; Fittinghoff, D.N.; Friedrich, S.; Glenzer, S.; Haan, S.; Hatarik, R.; Hatchett, S.; Jones, O.S.; Glebov, V.Yu.; Knauer, J.P.; Grim, G.; Kilkenny, J.D.

2013-01-01

The neutron spectrum from a cryogenically layered deuterium–tritium (dt) implosion at the National Ignition Facility (NIF) provides essential information about the implosion performance. From the measured primary-neutron spectrum (13–15 MeV), yield (Y n ) and hot-spot ion temperature (T i ) are determined. From the scattered neutron yield (10–12 MeV) relative to Y n , the down-scatter ratio, and the fuel areal density (ρR) are determined. These implosion parameters have been diagnosed to an unprecedented accuracy with a suite of neutron-time-of-flight spectrometers and a magnetic recoil spectrometer implemented in various locations around the NIF target chamber. This provides good implosion coverage and excellent measurement complementarity required for reliable measurements of Y n , T i and ρR, in addition to ρR asymmetries. The data indicate that the implosion performance, characterized by the experimental ignition threshold factor, has improved almost two orders of magnitude since the first shot taken in September 2010. ρR values greater than 1 g cm −2 are readily achieved. Three-dimensional semi-analytical modelling and numerical simulations of the neutron-spectrometry data, as well as other data for the hot spot and main fuel, indicate that a maximum hot-spot pressure of ∼150 Gbar has been obtained, which is almost a factor of two from the conditions required for ignition according to simulations. Observed Y n are also 3–10 times lower than predicted. The conjecture is that the observed pressure and Y n deficits are partly explained by substantial low-mode ρR asymmetries, which may cause inefficient conversion of shell kinetic energy to hot-spot thermal energy at stagnation. (paper)

Status of Indirect Drive ICF Experiments on the National Ignition Facility

International Nuclear Information System (INIS)

Dewald, E.

2016-01-01

In the quest to demonstrate Inertial Confinement Fusion (ICF) ignition of deuterium-tritium (DT) filled capsules and propagating thermonuclear burn with net energy gain (fusion energy/laser energy >1), recent experiments on the National Ignition Facility (NIF) have shown progress towards increasing capsule hot spot temperature (T ion >5 keV) and fusion neutron yield (~10 16 ), while achieving ~2x yield amplification by alpha particle deposition. At the same time a performance cliff was reached, resulting in lower fusion yields than expected as the implosion velocity was increased. Ongoing studies of the hohlraum and capsule physics are attempting to disseminate possible causes for this performance ceiling.

Theory of hydro-equivalent ignition for inertial fusion and its applications to OMEGA and the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Nora, R.; Betti, R.; Bose, A.; Woo, K. M.; Christopherson, A. R.; Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Fusion Science Center, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and/or Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Anderson, K. S.; Shvydky, A.; Marozas, J. A.; Collins, T. J. B.; Radha, P. B.; Hu, S. X.; Epstein, R.; Marshall, F. J.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); McCrory, R. L. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Physics and/or Mechanical Engineering, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

2014-05-15

The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements for cryogenic implosion experiments on the Omega Laser Facility. The theory of hydrodynamic similarity is developed in both one and two dimensions and tested using multimode hydrodynamic simulations with the hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] of hydro-equivalent implosions (implosions with the same implosion velocity, adiabat, and laser intensity). The theory is used to scale the performance of direct-drive OMEGA implosions to the National Ignition Facility (NIF) energy scales and determine the requirements for demonstrating hydro-equivalent ignition on OMEGA. Hydro-equivalent ignition on OMEGA is represented by a cryogenic implosion that would scale to ignition on the NIF at 1.8 MJ of laser energy symmetrically illuminating the target. It is found that a reasonable combination of neutron yield and areal density for OMEGA hydro-equivalent ignition is 3 to 6 × 10{sup 13} and ∼0.3 g/cm{sup 2}, respectively, depending on the level of laser imprinting. This performance has not yet been achieved on OMEGA.

Theory of hydro-equivalent ignition for inertial fusion and its applications to OMEGA and the National Ignition Facility

International Nuclear Information System (INIS)

Nora, R.; Betti, R.; Bose, A.; Woo, K. M.; Christopherson, A. R.; Meyerhofer, D. D.; Anderson, K. S.; Shvydky, A.; Marozas, J. A.; Collins, T. J. B.; Radha, P. B.; Hu, S. X.; Epstein, R.; Marshall, F. J.; Sangster, T. C.; McCrory, R. L.

2014-01-01

The theory of ignition for inertial confinement fusion capsules [R. Betti et al., Phys. Plasmas 17, 058102 (2010)] is used to assess the performance requirements for cryogenic implosion experiments on the Omega Laser Facility. The theory of hydrodynamic similarity is developed in both one and two dimensions and tested using multimode hydrodynamic simulations with the hydrocode DRACO [P. B. Radha et al., Phys. Plasmas 12, 032702 (2005)] of hydro-equivalent implosions (implosions with the same implosion velocity, adiabat, and laser intensity). The theory is used to scale the performance of direct-drive OMEGA implosions to the National Ignition Facility (NIF) energy scales and determine the requirements for demonstrating hydro-equivalent ignition on OMEGA. Hydro-equivalent ignition on OMEGA is represented by a cryogenic implosion that would scale to ignition on the NIF at 1.8 MJ of laser energy symmetrically illuminating the target. It is found that a reasonable combination of neutron yield and areal density for OMEGA hydro-equivalent ignition is 3 to 6 × 10 13 and ∼0.3 g/cm 2 , respectively, depending on the level of laser imprinting. This performance has not yet been achieved on OMEGA

Imaging of high-energy x-ray emission from cryogenic thermonuclear fuel implosions on the NIF.

Science.gov (United States)

Ma, T; Izumi, N; Tommasini, R; Bradley, D K; Bell, P; Cerjan, C J; Dixit, S; Döppner, T; Jones, O; Kline, J L; Kyrala, G; Landen, O L; LePape, S; Mackinnon, A J; Park, H-S; Patel, P K; Prasad, R R; Ralph, J; Regan, S P; Smalyuk, V A; Springer, P T; Suter, L; Town, R P J; Weber, S V; Glenzer, S H

2012-10-01

Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide broadband time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered implosions. This diagnostic measures the temperature- and density-sensitive bremsstrahlung emission and provides estimates of hot spot mass, mix mass, and pressure.

Imaging of high-energy x-ray emission from cryogenic thermonuclear fuel implosions on the NIF

Energy Technology Data Exchange (ETDEWEB)

Ma, T.; Izumi, N.; Tommasini, R.; Bradley, D. K.; Bell, P.; Cerjan, C. J.; Dixit, S.; Doeppner, T.; Jones, O.; Landen, O. L.; LePape, S.; Mackinnon, A. J.; Park, H.-S.; Patel, P. K.; Prasad, R. R.; Ralph, J.; Smalyuk, V. A.; Springer, P. T.; Suter, L.; Town, R. P. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2012-10-15

Accurately assessing and optimizing the implosion performance of inertial confinement fusion capsules is a crucial step to achieving ignition on the NIF. We have applied differential filtering (matched Ross filter pairs) to provide broadband time-integrated absolute x-ray self-emission images of the imploded core of cryogenic layered implosions. This diagnostic measures the temperature- and density-sensitive bremsstrahlung emission and provides estimates of hot spot mass, mix mass, and pressure.

Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions.

Science.gov (United States)

Mackinnon, A J; Kline, J L; Dixit, S N; Glenzer, S H; Edwards, M J; Callahan, D A; Meezan, N B; Haan, S W; Kilkenny, J D; Döppner, T; Farley, D R; Moody, J D; Ralph, J E; MacGowan, B J; Landen, O L; Robey, H F; Boehly, T R; Celliers, P M; Eggert, J H; Krauter, K; Frieders, G; Ross, G F; Hicks, D G; Olson, R E; Weber, S V; Spears, B K; Salmonsen, J D; Michel, P; Divol, L; Hammel, B; Thomas, C A; Clark, D S; Jones, O S; Springer, P T; Cerjan, C J; Collins, G W; Glebov, V Y; Knauer, J P; Sangster, C; Stoeckl, C; McKenty, P; McNaney, J M; Leeper, R J; Ruiz, C L; Cooper, G W; Nelson, A G; Chandler, G G A; Hahn, K D; Moran, M J; Schneider, M B; Palmer, N E; Bionta, R M; Hartouni, E P; LePape, S; Patel, P K; Izumi, N; Tommasini, R; Bond, E J; Caggiano, J A; Hatarik, R; Grim, G P; Merrill, F E; Fittinghoff, D N; Guler, N; Drury, O; Wilson, D C; Herrmann, H W; Stoeffl, W; Casey, D T; Johnson, M G; Frenje, J A; Petrasso, R D; Zylestra, A; Rinderknecht, H; Kalantar, D H; Dzenitis, J M; Di Nicola, P; Eder, D C; Courdin, W H; Gururangan, G; Burkhart, S C; Friedrich, S; Blueuel, D L; Bernstein, L A; Eckart, M J; Munro, D H; Hatchett, S P; Macphee, A G; Edgell, D H; Bradley, D K; Bell, P M; Glenn, S M; Simanovskaia, N; Barrios, M A; Benedetti, R; Kyrala, G A; Town, R P J; Dewald, E L; Milovich, J L; Widmann, K; Moore, A S; LaCaille, G; Regan, S P; Suter, L J; Felker, B; Ashabranner, R C; Jackson, M C; Prasad, R; Richardson, M J; Kohut, T R; Datte, P S; Krauter, G W; Klingman, J J; Burr, R F; Land, T A; Hermann, M R; Latray, D A; Saunders, R L; Weaver, S; Cohen, S J; Berzins, L; Brass, S G; Palma, E S; Lowe-Webb, R R; McHalle, G N; Arnold, P A; Lagin, L J; Marshall, C D; Brunton, G K; Mathisen, D G; Wood, R D; Cox, J R; Ehrlich, R B; Knittel, K M; Bowers, M W; Zacharias, R A; Young, B K; Holder, J P; Kimbrough, J R; Ma, T; La Fortune, K N; Widmayer, C C; Shaw, M J; Erbert, G V; Jancaitis, K S; DiNicola, J M; Orth, C; Heestand, G; Kirkwood, R; Haynam, C; Wegner, P J; Whitman, P K; Hamza, A; Dzenitis, E G; Wallace, R J; Bhandarkar, S D; Parham, T G; Dylla-Spears, R; Mapoles, E R; Kozioziemski, B J; Sater, J D; Walters, C F; Haid, B J; Fair, J; Nikroo, A; Giraldez, E; Moreno, K; Vanwonterghem, B; Kauffman, R L; Batha, S; Larson, D W; Fortner, R J; Schneider, D H; Lindl, J D; Patterson, R W; Atherton, L J; Moses, E I

2012-05-25

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1-1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275-300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of 25-35 μm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).

X-ray penumbral imaging diagnostic developments at the National Ignition Facility

Science.gov (United States)

Bachmann, B.; Abu-Shawareb, H.; Alexander, N.; Ayers, J.; Bailey, C. G.; Bell, P.; Benedetti, L. R.; Bradley, D.; Collins, G.; Divol, L.; Döppner, T.; Felker, S.; Field, J.; Forsman, A.; Galbraith, J. D.; Hardy, C. M.; Hilsabeck, T.; Izumi, N.; Jarrot, C.; Kilkenny, J.; Kramer, S.; Landen, O. L.; Ma, T.; MacPhee, A.; Masters, N.; Nagel, S. R.; Pak, A.; Patel, P.; Pickworth, L. A.; Ralph, J. E.; Reed, C.; Rygg, J. R.; Thorn, D. B.

2017-08-01

X-ray penumbral imaging has been successfully fielded on a variety of inertial confinement fusion (ICF) capsule implosion experiments on the National Ignition Facility (NIF). We have demonstrated sub-5 μm resolution imaging of stagnated plasma cores (hot spots) at x-ray energies from 6 to 30 keV. These measurements are crucial for improving our understanding of the hot deuterium-tritium fuel assembly, which can be affected by various mechanisms, including complex 3-D perturbations caused by the support tent, fill tube or capsule surface roughness. Here we present the progress on several approaches to improve x-ray penumbral imaging experiments on the NIF. We will discuss experimental setups that include penumbral imaging from multiple lines-of-sight, target mounted penumbral apertures and variably filtered penumbral images. Such setups will improve the signal-to-noise ratio and the spatial imaging resolution, with the goal of enabling spatially resolved measurements of the hot spot electron temperature and material mix in ICF implosions.

Introduction to the physics of ICF capsules

International Nuclear Information System (INIS)

Lindl, J.D.

1989-01-01

Inertial Confinement Fusion is an approach to fusion which relies on the inertia of the fuel mass to provide confinement. To achieve conditions under which this confinement is sufficient for efficient thermonuclear burn, high gain ICF targets designed to be imploded directly by laser light. These capsules are generally a spherical shell which is filled with low density DT gas. The shell is composed of an outer region which forms the ablator and an inner region of frozen or liquid DT which forms the main fuel. Energy from the driver is delivered to the ablator which heats up and expands. As the ablator expands and blows outward, the rest of the shell is forced inward to conserve momentum. In this implosion process, several features are important. We define the in-flight-aspect-ratio (IFAR) as the ratio of the shell radius R as it implodes to its thickness ΔR. Hydrodynamic instabilities during the implosion impose limits on this ratio which results in a minimum pressure requirement of about 100 Mbar. The convergence ratio is defined as the ratio of the initial outer radius of the ablator to the final compressed radius of the hot spot. This hot spot is the central region of the compressed fuel which is required to ignite the main fuel in high gain designs. Typical convergence ratios are 30--40. To maintain a nearly spherical shape during the implosion, when convergence ratios are this large, the flux delivered to the capsule must be uniform to a few percent. The remainder of this paper discusses the conditions necessary to achieve thermonuclear ignition in these ICF capsules

Simulations of laser imprint for Nova experiments and for ignition capsules. Revision 1

International Nuclear Information System (INIS)

Weber, S.V.; Glendinning, S.G.; Kalantar, D.H.; Key, M.H.; Remington, B.A.; Rothenberg, J.L.; Wolfrum, E.; Verdon, C.P.; Knauer, J.P.

1996-12-01

In direct drive ICF, nonuniformities in laser illumination seed ripples at the ablation front in a process called ''imprint''. These nonuniformities grow during the capsule implosion and, if initially large enough, can penetrate the capsule shell, impede ignition, or degrade burn. Imprint has been simulated for recent experiments performed on the Nova laser at LLNL examining a variety of beam smoothing conditions. Most used laser intensities similar to the early part of an ignition capsule pulse shape, 1 ≅ 10 13 W/cm 2 . The simulations matched most of the measurements of imprint modulation. The effect of imprint upon National Ignition Facility (NIF) direct drive ignition capsules has also been simulated. Imprint is predicted to give modulation comparable to an intrinsic surface finish of ∼10 nm RMS. Modulation growth was examined using the Haan [Phys. Rev. A 39, 5812 (1989)] model, with linear growth factors as a function of spherical harmonic mode number obtained from an analytic dispersion relation. Ablation front amplitudes are predicted to become substantially nonlinear, so that saturation corrections are large. Direct numerical simulations of two-dimensional multimode growth were also performed. The capsule shell is predicted to remain intact, which gives a basis for believing that ignition can be achieved. 27 refs., 10 figs

Hohlraum drive and implosion experiments on Nova. Revision 1

International Nuclear Information System (INIS)

Kilkenny, J.D.; Suter, L.J.; Cable, M.D.

1994-01-01

Experiments on Nova have demonstrated hohlraum radiation temperatures up to 300 eV and in lower temperature experiments reproducible time integrated symmetry to 1--2%. Detailed 2-D LASNEX simulations satisfactorily reproduce Nova's drive and symmetry scaling data bases. Hohlraums has been used for implosion experiments achieving convergence ratios (initial capsule radius/final fuel radius) up to 24 with high density glass surrounding a hot gas fill

Automated analysis of hot spot X-ray images at the National Ignition Facility

Science.gov (United States)

Khan, S. F.; Izumi, N.; Glenn, S.; Tommasini, R.; Benedetti, L. R.; Ma, T.; Pak, A.; Kyrala, G. A.; Springer, P.; Bradley, D. K.; Town, R. P. J.

2016-11-01

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ˜4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Automated analysis of hot spot X-ray images at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Khan, S. F., E-mail: khan9@llnl.gov; Izumi, N.; Glenn, S.; Tommasini, R.; Benedetti, L. R.; Ma, T.; Pak, A.; Springer, P.; Bradley, D. K.; Town, R. P. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Kyrala, G. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2016-11-15

At the National Ignition Facility, the symmetry of the hot spot of imploding capsules is diagnosed by imaging the emitted x-rays using gated cameras and image plates. The symmetry of an implosion is an important factor in the yield generated from the resulting fusion process. The x-ray images are analyzed by decomposing the image intensity contours into Fourier and Legendre modes. This paper focuses on the additional protocols for the time-integrated shape analysis from image plates. For implosions with temperatures above ∼4 keV, the hard x-ray background can be utilized to infer the temperature of the hot spot.

Wavelength Detuning Cross-Beam Energy Transfer Mitigation Scheme for Direct-Drive: Modeling and Evidence from National Ignition Facility Implosions

Science.gov (United States)

Marozas, J. A.

2017-10-01

Cross-beam energy transfer (CBET) has been shown to significantly reduce the laser absorption and implosion speed in direct-drive implosion experiments on OMEGA and the National Ignition Facility (NIF). Mitigating CBET assists in achieving ignition-relevant hot-spot pressures in deuterium-tritium cryogenic OMEGA implosions. In addition, reducing CBET permits lower, more hydrodynamically stable, in-flight aspect ratio ignition designs with smaller nonuniformity growth during the acceleration phase. Detuning the wavelengths of the crossing beams is one of several techniques under investigation at the University of Rochester to mitigate CBET. This talk will describe these techniques with an emphasis on wavelength detuning. Recent experiments designed and predicted using multidimensional hydrodynamic simulations including CBET on the NIF have exploited the wavelength arrangement of the NIF beam geometry to demonstrate CBET mitigation through wavelength detuning in polar-direct-drive (PDD) implosions. Shapes and trajectories inferred from time-resolved x-ray radiography of the imploding shell, scattered-light spectra, and hard x-ray spectra generated by suprathermal electrons all indicate a reduction in CBET. These results and their implications for direct-drive ignition will be presented and discussed. In addition, hydrodynamically scaled ignition-relevant designs for OMEGA implosions exploiting wavelength detuning will be presented. Changes required to the OMEGA laser to permit wavelength detuning will be discussed. Future plans for PDD on the NIF including more-uniform implosions with CBET mitigation will be explored. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Equilibrium ignition for ICF capsules

International Nuclear Information System (INIS)

Lackner, K.S.; Colgate, S.A.; Johnson, N.L.; Kirkpatrick, R.C.; Menikoff, R.; Petschek, A.G.

1993-01-01

There are two fundamentally different approaches to igniting DT fuel in an ICF capsule which can be described as equilibrium and hot spot ignition. In both cases, a capsule which can be thought of as a pusher containing the DT fuel is imploded until the fuel reaches ignition conditions. In comparing high-gain ICF targets using cryogenic DT for a pusher with equilibrium ignition targets using high-Z pushers which contain the radiation. The authors point to the intrinsic advantages of the latter. Equilibrium or volume ignition sacrifices high gain for lower losses, lower ignition temperature, lower implosion velocity and lower sensitivity of the more robust capsule to small fluctuations and asymmetries in the drive system. The reduction in gain is about a factor of 2.5, which is small enough to make the more robust equilibrium ignition an attractive alternative

Hard x-ray (>100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the NIF.

Science.gov (United States)

Döppner, T; Dewald, E L; Divol, L; Thomas, C A; Burns, S; Celliers, P M; Izumi, N; Kline, J L; LaCaille, G; McNaney, J M; Prasad, R R; Robey, H F; Glenzer, S H; Landen, O L

2012-10-01

We have fielded a hard x-ray (>100 keV) imager with high aspect ratio pinholes to measure the spatially resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions and are a source of preheat to the deuterium-tritium fuel. First measurements show that hot electron preheat does not limit obtaining the fuel areal densities required for ignition and burn.

Diagnosing and controlling mix in National Ignition Facility implosion experiments

International Nuclear Information System (INIS)

Hammel, B. A.; Scott, H. A.; Cerjan, C.; Clark, D. S.; Edwards, M. J.; Glenzer, S. H.; Haan, S. W.; Izumi, N.; Koch, J. A.; Landen, O. L.; Langer, S. H.; Smalyuk, V. A.; Suter, L. J.; Regan, S. P.; Epstein, R.; Kyrala, G. A.; Wilson, D. C.; Peterson, K.

2011-01-01

High mode number instability growth of ''isolated defects'' on the surfaces of National Ignition Facility [Moses et al., Phys. Plasmas 16, 041006 (2009)] capsules can be large enough for the perturbation to penetrate the imploding shell, and produce a jet of ablator material that enters the hot-spot. Since internal regions of the CH ablator are doped with Ge, mixing of this material into the hot-spot results in a clear signature of Ge K-shell emission. Evidence of jets entering the hot-spot has been recorded in x-ray images and spectra, consistent with simulation predictions [Hammel et al., High Energy Density Phys. 6, 171 (2010)]. Ignition targets have been designed to minimize instability growth, and capsule fabrication improvements are underway to reduce ''isolated defects.'' An experimental strategy has been developed where the final requirements for ignition targets can be adjusted through direct measurements of mix and experimental tuning.

Exploring the limits of case-to-capsule ratio, pulse length, and picket energy for symmetric hohlraum drive on the National Ignition Facility Laser

Science.gov (United States)

Callahan, D. A.; Hurricane, O. A.; Ralph, J. E.; Thomas, C. A.; Baker, K. L.; Benedetti, L. R.; Berzak Hopkins, L. F.; Casey, D. T.; Chapman, T.; Czajka, C. E.; Dewald, E. L.; Divol, L.; Döppner, T.; Hinkel, D. E.; Hohenberger, M.; Jarrott, L. C.; Khan, S. F.; Kritcher, A. L.; Landen, O. L.; LePape, S.; MacLaren, S. A.; Masse, L. P.; Meezan, N. B.; Pak, A. E.; Salmonson, J. D.; Woods, D. T.; Izumi, N.; Ma, T.; Mariscal, D. A.; Nagel, S. R.; Kline, J. L.; Kyrala, G. A.; Loomis, E. N.; Yi, S. A.; Zylstra, A. B.; Batha, S. H.

2018-05-01

We present a data-based model for low mode asymmetry in low gas-fill hohlraum experiments on the National Ignition Facility {NIF [Moses et al., Fusion Sci. Technol. 69, 1 (2016)]} laser. This model is based on the hypothesis that the asymmetry in these low fill hohlraums is dominated by the hydrodynamics of the expanding, low density, high-Z (gold or uranium) "bubble," which occurs where the intense outer cone laser beams hit the high-Z hohlraum wall. We developed a simple model which states that the implosion symmetry becomes more oblate as the high-Z bubble size becomes large compared to the hohlraum radius or the capsule size becomes large compared to the hohlraum radius. This simple model captures the trends that we see in data that span much of the parameter space of interest for NIF ignition experiments. We are now using this model as a constraint on new designs for experiments on the NIF.

Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

International Nuclear Information System (INIS)

Spears, B.K.; Glenzer, S.; Edwards, M.J.; Brandon, S.; Clark, D.; Town, R.; Cerjan, C.; Dylla-Spears, R.; Mapoles, E.; Munro, D.; Salmonson, J.; Sepke, S.; Weber, S.; Hatchett, S.; Haan, S.; Springer, P.; Moses, E.; Mapoles, E.; Munro, D.; Salmonson, J.; Sepke, S.

2011-01-01

The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.

Performance metrics for Inertial Confinement Fusion implosions: aspects of the technical framework for measuring progress in the National Ignition Campaign

Energy Technology Data Exchange (ETDEWEB)

Spears, B K; Glenzer, S; Edwards, M J; Brandon, S; Clark, D; Town, R; Cerjan, C; Dylla-Spears, R; Mapoles, E; Munro, D; Salmonson, J; Sepke, S; Weber, S; Hatchett, S; Haan, S; Springer, P; Moses, E; Mapoles, E; Munro, D; Salmonson, J; Sepke, S

2011-12-16

The National Ignition Campaign (NIC) uses non-igniting 'THD' capsules to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are designed to simultaneously reduce DT neutron yield and to maintain hydrodynamic similarity with the DT ignition capsule. We will discuss nominal THD performance and the associated experimental observables. We will show the results of large ensembles of numerical simulations of THD and DT implosions and their simulated diagnostic outputs. These simulations cover a broad range of both nominal and off nominal implosions. We will focus on the development of an experimental implosion performance metric called the experimental ignition threshold factor (ITFX). We will discuss the relationship between ITFX and other integrated performance metrics, including the ignition threshold factor (ITF), the generalized Lawson criterion (GLC), and the hot spot pressure (HSP). We will then consider the experimental results of the recent NIC THD campaign. We will show that we can observe the key quantities for producing a measured ITFX and for inferring the other performance metrics. We will discuss trends in the experimental data, improvement in ITFX, and briefly the upcoming tuning campaign aimed at taking the next steps in performance improvement on the path to ignition on NIF.

Recovery, Transportation and Acceptance to the Curation Facility of the Hayabusa Re-Entry Capsule

Science.gov (United States)

Abe, M.; Fujimura, A.; Yano, H.; Okamoto, C.; Okada, T.; Yada, T.; Ishibashi, Y.; Shirai, K.; Nakamura, T.; Noguchi, T.;

Optimization of a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications in nucleosynthesis experiments

Science.gov (United States)

Gatu Johnson, M.; Casey, D. T.; Hohenberger, M.; Zylstra, A. B.; Bacher, A.; Brune, C. R.; Bionta, R. M.; Craxton, R. S.; Ellison, C. L.; Farrell, M.; Frenje, J. A.; Garbett, W.; Garcia, E. M.; Grim, G. P.; Hartouni, E.; Hatarik, R.; Herrmann, H. W.; Hohensee, M.; Holunga, D. M.; Hoppe, M.; Jackson, M.; Kabadi, N.; Khan, S. F.; Kilkenny, J. D.; Kohut, T. R.; Lahmann, B.; Le, H. P.; Li, C. K.; Masse, L.; McKenty, P. W.; McNabb, D. P.; Nikroo, A.; Parham, T. G.; Parker, C. E.; Petrasso, R. D.; Pino, J.; Remington, B.; Rice, N. G.; Rinderknecht, H. G.; Rosenberg, M. J.; Sanchez, J.; Sayre, D. B.; Schoff, M. E.; Shuldberg, C. M.; Séguin, F. H.; Sio, H.; Walters, Z. B.; Whitley, H. D.

2018-05-01

Polar-direct-drive exploding pushers are used as a high-yield, low-areal-density fusion product source at the National Ignition Facility with applications including diagnostic calibration, nuclear security, backlighting, electron-ion equilibration, and nucleosynthesis-relevant experiments. In this paper, two different paths to improving the performance of this platform are explored: (i) optimizing the laser drive, and (ii) optimizing the target. While the present study is specifically geared towards nucleosynthesis experiments, the results are generally applicable. Example data from T2/3He-gas-filled implosions with trace deuterium are used to show that yield and ion temperature (Tion) from 1.6 mm-outer-diameter thin-glass-shell capsule implosions are improved at a set laser energy by switching from a ramped to a square laser pulse shape, and that increased laser energy further improves yield and Tion, although by factors lower than predicted by 1 D simulations. Using data from D2/3He-gas-filled implosions, yield at a set Tion is experimentally verified to increase with capsule size. Uniform D3He-proton spectra from 3 mm-outer-diameter CH shell implosions demonstrate the utility of this platform for studying charged-particle-producing reactions relevant to stellar nucleosynthesis.

Simulation of instability growth on ICF capsule ablators

Science.gov (United States)

Niasse, Nicolas; Chittenden, Jeremy

2014-10-01

It is believed that the ablation-front instabilities are mainly responsible for the hot-spot mix that impacts the performance of ICF capsules. Understanding the formation of these instabilities is therefore a first step towards a better control of the implosion dynamics and the optimization of the fusion yield. Using the Chimera code currently in development at Imperial College, we have performed several spherical wedge simulations of the low and high adiabat ablation phase pre-imposing different single-mode 2D and 3D perturbations on the capsule surface. Synthetic Sc, Fe and V X-ray backlighter images are generated by the Spk code and used to measure the growth of modes 30-160 with initial amplitude <= 3.4 μm PTV. The growth of imposed 2D perturbations is assessed for both low-foot and high-foot radiation pulse shapes on the National Ignition Facility. Results showing the merger of spike and bubble structures in multi-mode perturbations in both 2D and 3D simulations are explored and preliminary assessments of the difference between 2D and 3D non-linear behaviour is discussed. The sensitivity of shock timing to NLTE changes in opacity is also assessed.

Lasers and laser applications. Imaging implosion dynamics: The x-ray pinhole/streak camera

International Nuclear Information System (INIS)

Attwood, D.T.

1976-01-01

A Livermore-developed x-ray-sensitive streak camera was combined with a unique x-ray pinhole camera to make dynamic photographs of laser-irradiated fusion target implosions. These photographs show x radiation emitted from the imploding shell during its 100-ps implosion; they are the first continuous observations of an imploding laser-driven fusion capsule. The diagnostic system has a time resolution of 15 ps and a spatial resolution of about 6 μm. Results agree very well with those predicted by our LASNEX calculations, confirming that the essential physics are correctly described in the code and providing further confidence in the soundness of this approach to inertial confinement fusion

3D Simulations of NIF Wetted Foam Experiments to Understand the Transition from 2D to 3D Implosion Behavior

Science.gov (United States)

Haines, Brian; Olson, Richard; Yi, Austin; Zylstra, Alex; Peterson, Robert; Bradley, Paul; Shah, Rahul; Wilson, Doug; Kline, John; Leeper, Ramon; Batha, Steve

2017-10-01

The high convergence ratio (CR) of layered Inertial Confinement Fusion capsule implosions contribute to high performance in 1D simulations yet make them more susceptible to hydrodynamic instabilities, contributing to the development of 3D flows. The wetted foam platform is an approach to hot spot ignition to achieve low-to-moderate convergence ratios in layered implosions on the NIF unobtainable using an ice layer. Detailed high-resolution modeling of these experiments in 2D and 3D, including all known asymmetries, demonstrates that 2D hydrodynamics explain capsule performance at CR 12 but become less suitable as the CR increases. Mechanisms for this behavior and detailed comparisons of simulations to experiments on NIF will be presented. To evaluate the tradeoff between increased instability and improved 1D performance, we present a full-scale wetted foam capsule design with 17

Facile and Scalable Synthesis of Monodispersed Spherical Capsules with a Mesoporous Shell

KAUST Repository

Qi, Genggeng

2010-05-11

Monodispersed HMSs with tunable particle size and shell thickness were successfully synthesized using relatively concentrated polystyrene latex templates and a silica precursor in a weakly basic ethanol/water mixture. The particle size of the capsules can vary from 100 nm to micrometers. These highly engineered monodispersed capsules synthesized by a facile and scalable process may find applications in drug delivery, catalysis, separationm or as biological and chemical microreactors. © 2010 American Chemical Society.

Advances in shock timing experiments on the National Ignition Facility

International Nuclear Information System (INIS)

Robey, H F; Celliers, P M; Moody, J D; Sater, J; Parham, T; Kozioziemski, B; Dylla- Spears, R; Ross, J S; LePape, S; Ralph, J E; Hohenberger, M; Dewald, E L; Berzak Hopkins, L; Kroll, J J; Yoxall, B E; Hamza, A V; Landen, O L; Edwards, M J; Boehly, T R; Nikroo, A

2016-01-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion (ICF) implosions were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique. (paper)

Advances in shock timing experiments on the National Ignition Facility

Science.gov (United States)

Robey, H. F.; Celliers, P. M.; Moody, J. D.; Sater, J.; Parham, T.; Kozioziemski, B.; Dylla-Spears, R.; Ross, J. S.; LePape, S.; Ralph, J. E.; Hohenberger, M.; Dewald, E. L.; Berzak Hopkins, L.; Kroll, J. J.; Yoxall, B. E.; Hamza, A. V.; Boehly, T. R.; Nikroo, A.; Landen, O. L.; Edwards, M. J.

2016-03-01

Recent advances in shock timing experiments and analysis techniques now enable shock measurements to be performed in cryogenic deuterium-tritium (DT) ice layered capsule implosions on the National Ignition Facility (NIF). Previous measurements of shock timing in inertial confinement fusion (ICF) implosions were performed in surrogate targets, where the solid DT ice shell and central DT gas were replaced with a continuous liquid deuterium (D2) fill. These previous experiments pose two surrogacy issues: a material surrogacy due to the difference of species (D2 vs. DT) and densities of the materials used and a geometric surrogacy due to presence of an additional interface (ice/gas) previously absent in the liquid-filled targets. This report presents experimental data and a new analysis method for validating the assumptions underlying this surrogate technique.

Study of Implosion of Combined Nested Arrays

Science.gov (United States)

Mitrofanov, K. N.; Aleksandrov, V. V.; Grabovski, E. V.; Sasorov, P. V.; Branitsky, A. V.; Gritsuk, A. N.; Frolov, I. N.; Laukhin, Ya. N.

2017-12-01

New experimental data on the implosion of plasma of nested kapron-tungsten arrays are obtained at the Angara-5-1 facility. The mode of plasma implosion is implemented in which a shock wave region forms in the space between the inner and outer arrays where a transition from the super-Alfvénic ( V r > V A ) to sub-Alfvénic ( V r Z-pinch and generation of a soft X-ray pulse with a peak power of 4 TW and duration of about 5 ns.

Progress Towards Ignition on the National Ignition Facility

Science.gov (United States)

Edwards, John

2012-10-01

Since completion of the National Ignition Facility (NIF) construction project in March 2009, a wide variety of diagnostics, facility infrastructure, and experimental platforms have been commissioned in pursuit of generating the conditions necessary to reach thermonuclear ignition in the laboratory via the inertial confinement approach. NIF's capabilities and infrastructure include over 50 X-ray, optical, and nuclear diagnostics systems and the ability to shoot cryogenic DT layered capsules. There are two main approaches to ICF: direct drive in which laser light impinges directly on a capsule containing a solid layer of DT fuel, and indirect drive in which the laser light is first converted to thermal X-rays. To date NIF has been conducting experiments using the indirect drive approach, injecting up to 1.8MJ of ultraviolet light (0.35 micron) into 1 cm scale cylindrical gold or gold-coated uranium, gas-filled hohlraums, to implode 1mm radius plastic capsules containing solid DT fuel layers. In order to achieve ignition conditions the implosion must be precisely controlled. The National Ignition Campaign (NIC), an international effort with the goal of demonstrating thermonuclear burn in the laboratory, is making steady progress toward this. Utilizing precision pulse-shaping experiments in early 2012 the NIC achieve fuel rhoR of approximately 1.2 gm/cm^2 with densities of around 600-800 g/cm^3 along with neutron yields within about a factor of 5 necessary to enter a regime in which alpha particle heating will become important. To achieve these results, experimental platforms were developed to carefully control key attributes of the implosion. This talk will review NIF's capabilities and the progress toward ignition, as well as the physics of ignition targets on NIF and on other facilities. Acknowledgement: this work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

High density implosion experiments at Nova

International Nuclear Information System (INIS)

Cable, M.D.; Hatchett, S.P.; Nelson, M.B.; Lerche, R.A.; Murphy, T.J.; Ress, D.B.

1994-01-01

Deuterium filled glass microballoons are used as indirectly driven targets for implosion experiments at the Nova Laser Fusion Facility. High levels of laser precision were required to achieve fuel densities and convergences to an ignition scale hot spot. (AIP) copyright 1994 American Institute of Physics

The high velocity, high adiabat, ``Bigfoot'' campaign and tests of indirect-drive implosion scaling

Science.gov (United States)

Casey, Daniel

2017-10-01

To achieve hotspot ignition, inertial confinement fusion (ICF) implosions must achieve high hotspot internal energy that is inertially confined by a dense shell of DT fuel. To accomplish this, implosions are designed to achieve high peak implosion velocity, good energy coupling between the hotspot and imploding shell, and high areal-density at stagnation. However, experiments have shown that achieving these simultaneously is extremely challenging, partly because of inherent tradeoffs between these three interrelated requirements. The Bigfoot approach is to intentionally trade off high convergence, and therefore areal-density, in favor of high implosion velocity and good coupling between the hotspot and shell. This is done by intentionally colliding the shocks in the DT ice layer. This results in a short laser pulse which improves hohlraum symmetry and predictability while the reduced compression improves hydrodynamic stability. The results of this campaign will be reviewed and include demonstrated low-mode symmetry control at two different hohlraum geometries (5.75 mm and 5.4 mm diameters) and at two different target scales (5.4 mm and 6.0 mm hohlraum diameters) spanning 300-430 TW in laser power and 0.8-1.7 MJ in laser energy. Results of the 10% scaling between these designs for the hohlraum and capsule will be presented. Hydrodynamic instability growth from engineering features like the capsule fill tube are currently thought to be a significant perturbation to the target performance and a major factor in reducing its performance compared to calculations. Evidence supporting this hypothesis as well as plans going forward will be presented. Ongoing experiments are attempting to measure the impact on target performance from increase in target scale, and the preliminary results will also be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Laser imprint and implications for direct drive ignition with the National Ignition Facility

International Nuclear Information System (INIS)

Weber, S.V.; Glendinning, S.G.; Kalantar, D.H.; Remington, B.A.; Rothenberg, J.E.

1996-01-01

For direct drive ICF, nonuniformities in laser illumination can seed ripples at the ablation front in a process called imprint. Such nonuniformities will grow during the capsule implosion and can penetrate the capsule shell impede ignition, or degrade burn. We have simulated imprint for a number of experiments on tile Nova laser. Results are in generally good agreement with experimental data. We leave also simulated imprint upon National Ignition Facility (NIF) direct drive ignition capsules. Imprint modulation amplitude comparable to the intrinsic surface finish of ∼40 nm is predicted for a laser bandwidth of 0.5 THz. Ablation front modulations experience growth factors up to several thousand, carrying modulation well into the nonlinear regime. Saturation modeling predicts that the shell should remain intact at the time of peak velocity, but penetration at earlier times appears more marginal

Implosions and hypertoric geometry

DEFF Research Database (Denmark)

Dancer, A.; Kirwan, F.; Swann, A.

2013-01-01

The geometry of the universal hyperkahler implosion for SU (n) is explored. In particular, we show that the universal hyperkahler implosion naturally contains a hypertoric variety described in terms of quivers. Furthermore, we discuss a gauge theoretic approach to hyperkahler implosion.......The geometry of the universal hyperkahler implosion for SU (n) is explored. In particular, we show that the universal hyperkahler implosion naturally contains a hypertoric variety described in terms of quivers. Furthermore, we discuss a gauge theoretic approach to hyperkahler implosion....

Membrane support of accelerated fuel capsules for inertial fusion energy reactors

International Nuclear Information System (INIS)

Petzoldt, R.W.; Moir, R.W.

1993-01-01

The use of a thin membrane to suspend an (inertial fusion energy) fuel capsule in a holder for injection into a reactor chamber is investigated. Capsule displacement and membrane deformation angle are calculated for an axisymmetric geometry for a range of membrane strain and capsule size. This information is used to calculate maximum target accelerations. Membranes must be thin (perhaps of order one micron) to minimize their effect on capsule implosion symmetry. For example, a 5 μm thick cryogenic mylar membrane is calculated to allow 1,000 m/s 2 acceleration of a 3 mm radius, 100 mg capsule. Vibration analysis (for a single membrane support) shows that if membrane vibration is not deliberately minimized, allowed acceleration may be reduced by a factor of four. A two membrane alternative geometry would allow several times greater acceleration. Therefore, alternative membrane geometry's should be used to provide greater target acceleration potential and reduce capsule displacement within the holder (for a given membrane thickness)

High-density carbon ablator experiments on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

MacKinnon, A. J., E-mail: mackinnon2@llnl.gov; Meezan, N. B.; Ross, J. S.; Le Pape, S.; Berzak Hopkins, L.; Divol, L.; Ho, D.; Milovich, J.; Pak, A.; Ralph, J.; Döppner, T.; Patel, P. K.; Thomas, C.; Tommasini, R.; Haan, S.; MacPhee, A. G.; McNaney, J.; Caggiano, J.; Hatarik, R.; Bionta, R. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); and others

2014-05-15

High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has a higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results in a thinner ablator with a larger inner radius for a given capsule scale. This leads to higher x-ray absorption and shorter laser pulses compared to equivalent CH designs. This paper will describe a series of experiments carried out to examine the feasibility of using HDC as an ablator using both gas filled hohlraums and lower density, near vacuum hohlraums. These experiments have shown that deuterium (DD) and deuterium-tritium gas filled HDC capsules driven by a hohlraum filled with 1.2 mg/cc He gas, produce neutron yields a factor of 2× higher than equivalent CH implosions, representing better than 50% Yield-over-Clean (YoC). In a near vacuum hohlraum (He = 0.03 mg/cc) with 98% laser-to-hohlraum coupling, such a DD gas-filled capsule performed near 1D expectations. A cryogenic layered implosion version was consistent with a fuel velocity = 410 ± 20 km/s with no observed ablator mixing into the hot spot.

X-ray imaging and spectroscopic measurements of implosions

International Nuclear Information System (INIS)

Hammel, B.A.; Ress, D.R.; Keane, C.J.; Kilkenny, J.D.; Landen, O.L.; Bell, P.; Pasha, R.; Wallace, R.J.; Bradley, D.K.

1992-01-01

Time-resolved x-ray measurements are essential in the investigation of laser-driven inertial confinement fusion, where neutron and x-ray emission are the only observable signatures of the compressed core conditions. High-speed detectors, available for x-ray measurement, provide a means of measuring the rapidly evolving conditions in imploding capsules on picosecond time scales. We address a wide range of issues in our indirectly driven implosion experiments on Nova, with a large variety of x-ray measurement techniques. Critical issues include symmetry of the compressed core, fuel density and temperature and hydrodynamic mix at the pusher/fuel interface

Hybrid strategy for increasing fusion performance and stagnation pressure in x-ray driven inertially confined fusion implosions on the NIF

Science.gov (United States)

Hurricane, O. A.; Callahan, D. A.; Edwards, M. J.; Casey, D.; Doeppner, T.; Hohenberger, M.; Hinkel, D.; Berzak Hopkins, L.; Le Pape, S.; MacLaren, S.; Masse, L.; Thomas, C.; Zylstra, A.

2017-10-01

Post NIC (2012), more stable and lower convergence implosions were developed and used as part of a `basecamp' strategy to identify obstacles to further performance. From 2013-2015 by probing away from a conservative working implosion in-steps towards conditions of higher velocity and compression, `Fuel Gain' and alpha-heating were obtained. In the process, performance cliffs unrelated to `mix' were identified the most impactful of which were symmetry control of the implosion and hydro seeded by engineering features. From 2015-2017 we focused on mitigating poor symmetry control and engineering improvements on fill-tubes and capsule mounting techniques. The results were more efficient implosions that can obtain the same performance levels as the earlier implosions, but with less laser energy. Presently, the best of these implosions is poised to step into a burning plasma state. Here, we describe the next step in our strategy that involves using the data we've acquired across parameter space to make a step to the largest symmetric implosions that can be fielded on NIF with the energy available. We describe the key principles that form the foundation of this approach. Performed under the auspices of U.S. Dept. of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

ICF implosion hotspot ion temperature diagnostic techniques based on neutron time-of-flight method

International Nuclear Information System (INIS)

Tang Qi; Song Zifeng; Chen Jiabin; Zhan Xiayu

2013-01-01

Ion temperature of implosion hotspot is a very important parameter for inertial confinement fusion. It reflects the energy level of the hotspot, and it is very sensitive to implosion symmetry and implosion speed. ICF implosion hotspot ion temperature diagnostic techniques based on neutron time-of-flight method were described. A neutron TOF spectrometer was developed using a ultrafast plastic scintillator as the neutron detector. Time response of the spectrometer has 1.1 ns FWHM and 0.5 ns rising time. TOF spectrum resolving method based on deconvolution and low pass filter was illuminated. Implosion hotspot ion temperature in low neutron yield and low ion temperature condition at Shenguang-Ⅲ facility was acquired using the diagnostic techniques. (authors)

First Observation of Cross-Beam Energy Transfer Mitigation for Direct-Drive Inertial Confinement Fusion Implosions Using Wavelength Detuning at the National Ignition Facility.

Science.gov (United States)

Marozas, J A; Hohenberger, M; Rosenberg, M J; Turnbull, D; Collins, T J B; Radha, P B; McKenty, P W; Zuegel, J D; Marshall, F J; Regan, S P; Sangster, T C; Seka, W; Campbell, E M; Goncharov, V N; Bowers, M W; Di Nicola, J-M G; Erbert, G; MacGowan, B J; Pelz, L J; Yang, S T

2018-02-23

Cross-beam energy transfer (CBET) results from two-beam energy exchange via seeded stimulated Brillouin scattering, which detrimentally reduces ablation pressure and implosion velocity in direct-drive inertial confinement fusion. Mitigating CBET is demonstrated for the first time in inertial-confinement implosions at the National Ignition Facility by detuning the laser-source wavelengths (±2.3  Å UV) of the interacting beams. We show that, in polar direct-drive, wavelength detuning increases the equatorial region velocity experimentally by 16% and alters the in-flight shell morphology. These experimental observations are consistent with design predictions of radiation-hydrodynamic simulations that indicate a 10% increase in the average ablation pressure.

Study of Implosion of Twisted Nested Arrays at the Angara-5-1 Facility

Science.gov (United States)

Mitrofanov, K. N.; Zukakishvili, G. G.; Aleksandrov, V. V.; Grabovski, E. V.; Frolov, I. N.; Gribov, A. N.

2018-01-01

Results are presented from experimental studies of the implosion of twisted nested arrays in which the wires of the outer and inner arrays are twisted about the array axis in opposite directions (clockwise and counterclockwise). Experiments with twisted arrays were carried out at the Angara-5-1 facility at currents of up to 4 MA. The currents through the arrays were switched either simultaneously or the current pulse through the outer array was delayed by 10-15 ns with the help of an anode spark gap. It is shown that, in such arrays, the currents flow along the inclined wires and, accordingly, there are both the azimuthal and axial components of the discharge current. The process of plasma implosion in twisted arrays depends substantially on the value of the axial (longitudinal) magnetic field generated inside the array by the azimuthal currents. Two-dimensional simulations of the magnetic field in twisted nested arrays were performed in the ( r, z) geometry with allowance for the skin effect in the discharge electrodes. It is shown that, depending on the geometry of the discharge electrodes, different configurations of the magnetic field can be implemented inside twisted nested arrays. The calculated magnetic configurations are compared with the results of measurements of the magnetic field inside such arrays. It is shown that the configuration of the axial magnetic field inside a twisted nested array depends substantially on the distribution of the azimuthal currents between the inner and outer arrays.

Engineering design of the LINUS-O prototype liner implosion system

International Nuclear Information System (INIS)

Turchi, P.J.; Jenkins, D.J.; Warnick, W.L.; Ford, R.D.; Lanham, R.; Cooper, A.L.; Burton, R.L.

1977-01-01

The development of imploding liner flux compression techniques for application to compact, pulsed fusion reactors has led to the concept of rotating liquid metal implosions driven by free-pistons. In hydrodynamic model tests, such implosions have been demonstrated to be stable and reversible, allowing serious consideration of a new class of pulsed fusion reactor. The next step is to demonstrate repetitive, controlled operation at high energy densities with liquid metal liners, for which peak magnetic field levels approaching a megagauss are possible. A prototype controlled liner implosion system, LINUS-O, has been designed and is under construction. During operation, the annular driving-piston surrounding the implosion chamber is displaced axially by the action of pulsed high pressure gas at several hundred atmospheres. The piston and chamber rotate at 2100 RPM, allowing the free inside surface of the liner to implode stably from 30 cm diameter to 1.0 cm at turnaround. The experimental facility is described and engineering problems associated with design and operation of controlled high energy implosion systems are discussed

Demonstrating ignition hydrodynamic equivalence in direct-drive cryogenic implosions on OMEGA

International Nuclear Information System (INIS)

Goncharov, V N; Regan, S P; Sangster, T C; Betti, R; Boehly, T R; Campbell, E M; Delettrez, J A; Edgell, D H; Epstein, R; Forrest, C J; Froula, D H; Glebov, V Yu; Harding, D R; Hu, S X; Igumenshchev, I V; Marshall, F J; McCrory, R L; Michel, D T; Myatt, J F; Radha, P B

2016-01-01

Achieving ignition in a direct-drive cryogenic implosion at the National Ignition Facility (NIF) requires reaching central stagnation pressures in excess of 100 Gbar, which is a factor of 3 to 4 less than what is required for indirect-drive designs. The OMEGA Laser System is used to study the physics of cryogenic implosions that are hydrodynamically equivalent to the spherical ignition designs of the NIF. Current cryogenic implosions on OMEGA have reached 56 Gbar, and implosions with shell convergence CR< 17 and fuel adiabat α > 3.5 proceed close to 1-D predictions. Demonstrating hydrodynamic equivalence on OMEGA will require reducing coupling losses caused by cross-beam energy transfer (CBET), minimizing long- wavelength nonuniformity seeded by power imbalance and target offset, and removing target debris occumulated during cryogenic target production. (paper)

Kinetic mix mechanisms in shock-driven inertial confinement fusion implosions

Energy Technology Data Exchange (ETDEWEB)

Rinderknecht, H. G.; Sio, H.; Li, C. K.; Zylstra, A. B.; Rosenberg, M. J.; Frenje, J. A.; Gatu Johnson, M.; Séguin, F. H.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Hoffman, N.; Kagan, G.; Molvig, K. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Betti, R.; Yu Glebov, V.; Meyerhofer, D. D.; Sangster, T. C.; Seka, W.; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Bellei, C.; Amendt, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2014-05-15

Shock-driven implosions of thin-shell capsules, or “exploding pushers,” generate low-density, high-temperature plasmas in which hydrodynamic instability growth is negligible and kinetic effects can play an important role. Data from implosions of thin deuterated-plastic shells with hydroequivalent D{sup 3}He gas fills ranging from pure deuterium to pure {sup 3}He [H. G. Rinderknecht et al., Phys. Rev. Lett. 112, 135001 (2014)] were obtained to evaluate non-hydrodynamic fuel-shell mix mechanisms. Simulations of the experiments including reduced ion kinetic models support ion diffusion as an explanation for these data. Several additional kinetic mechanisms are investigated and compared to the data to determine which are important in the experiments. Shock acceleration of shell deuterons is estimated to introduce mix less than or comparable to the amount required to explain the data. Beam-target mechanisms are found to produce yields at most an order of magnitude less than the observations.

In-flight observations of low-mode ρR asymmetries in NIF implosions

Energy Technology Data Exchange (ETDEWEB)

Zylstra, A. B., E-mail: zylstra@mit.edu; Frenje, J. A.; Séguin, F. H.; Rosenberg, M. J.; Rinderknecht, H. G.; Gatu Johnson, M.; Li, C. K.; Manuel, M. J.-E.; Petrasso, R. D.; Sinenian, N.; Sio, H. W. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Rygg, J. R.; Kritcher, A.; Hicks, D. G.; Friedrich, S.; Bionta, R.; Meezan, N. B.; Atherton, J.; Barrios, M.; Bell, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2015-05-15

Charged-particle spectroscopy is used to assess implosion symmetry in ignition-scale indirect-drive implosions for the first time. Surrogate D{sup 3}He gas-filled implosions at the National Ignition Facility produce energetic protons via D+{sup 3}He fusion that are used to measure the implosion areal density (ρR) at the shock-bang time. By using protons produced several hundred ps before the main compression bang, the implosion is diagnosed in-flight at a convergence ratio of 3–5 just prior to peak velocity. This isolates acceleration-phase asymmetry growth. For many surrogate implosions, proton spectrometers placed at the north pole and equator reveal significant asymmetries with amplitudes routinely ≳10%, which are interpreted as ℓ=2 Legendre modes. With significant expected growth by stagnation, it is likely that these asymmetries would degrade the final implosion performance. X-ray self-emission images at stagnation show asymmetries that are positively correlated with the observed in-flight asymmetries and comparable in magnitude, contradicting growth models; this suggests that the hot-spot shape does not reflect the stagnated shell shape or that significant residual kinetic energy exists at stagnation. More prolate implosions are observed when the laser drive is sustained (“no-coast”), implying a significant time-dependent asymmetry in peak drive.

Mitigate the tent-induced perturbation in ignition capsules by supersonic radiation propagation

Science.gov (United States)

Dai, Zhensheng; Gu, Jianfa; Zheng, Wudi

2017-10-01

In the inertial confinement fusion (ICF) scheme, to trap the alpha particle products of the D-T reaction, the capsules needs to be imploded and compressed with high symmetry In the laser indirect drive scheme, the capsules are held at the center of high-Z hohlraums by thin membranes (tents). However, the tents are recognized as one of the most important contributors to hot spot asymmetries, areal density perturbations and reduced performance. To improve the capsule implosion performance, various alternatives such as the micro-scale rods, a larger fill-tube and a low-density foam layer around the capsule have been presented. Our simulations show that the radiation propagates supersonically in the low-density foam layer and starts to ablate the capsule before the perturbations induced by the tents reach the ablating fronts. The tent induced perturbations are remarkably weakened when they are propagating in the blow-off plasma.

Effects of electron-ion temperature equilibration on inertial confinement fusion implosions.

Science.gov (United States)

Xu, Barry; Hu, S X

2011-07-01

The electron-ion temperature relaxation essentially affects both the laser absorption in coronal plasmas and the hot-spot formation in inertial confinement fusion (ICF). It has recently been reexamined for plasma conditions closely relevant to ICF implosions using either classical molecular-dynamics simulations or analytical methods. To explore the electron-ion temperature equilibration effects on ICF implosion performance, we have examined two Coulomb logarithm models by implementing them into our hydrocodes, and we have carried out hydrosimulations for ICF implosions. Compared to the Lee-More model that is currently used in our standard hydrocodes, the two models predict substantial differences in laser absorption, coronal temperatures, and neutron yields for ICF implosions at the OMEGA Laser Facility [Boehly et al. Opt. Commun. 133, 495 (1997)]. Such effects on the triple-picket direct-drive design at the National Ignition Facility (NIF) have also been explored. Based on the validity of the two models, we have proposed a combined model of the electron-ion temperature-relaxation rate for the overall ICF plasma conditions. The hydrosimulations using the combined model for OMEGA implosions have shown ∼6% more laser absorption, ∼6%-15% higher coronal temperatures, and ∼10% more neutron yield, when compared to the Lee-More model prediction. It is also noticed that the gain for the NIF direct-drive design can be varied by ∼10% among the different electron-ion temperature-relaxation models.

Observation of a reflected shock in an indirectly driven spherical implosion at the national ignition facility.

Science.gov (United States)

Le Pape, S; Divol, L; Berzak Hopkins, L; Mackinnon, A; Meezan, N B; Casey, D; Frenje, J; Herrmann, H; McNaney, J; Ma, T; Widmann, K; Pak, A; Grimm, G; Knauer, J; Petrasso, R; Zylstra, A; Rinderknecht, H; Rosenberg, M; Gatu-Johnson, M; Kilkenny, J D

2014-06-06

A 200  μm radius hot spot at more than 2 keV temperature, 1  g/cm^{3} density has been achieved on the National Ignition Facility using a near vacuum hohlraum. The implosion exhibits ideal one-dimensional behavior and 99% laser-to-hohlraum coupling. The low opacity of the remaining shell at bang time allows for a measurement of the x-ray emission of the reflected central shock in a deuterium plasma. Comparison with 1D hydrodynamic simulations puts constraints on electron-ion collisions and heat conduction. Results are consistent with classical (Spitzer-Harm) heat flux.

Hydrodynamic instabilities in beryllium targets for the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Yi, S. A., E-mail: austinyi@lanl.gov; Simakov, A. N.; Wilson, D. C.; Olson, R. E.; Kline, J. L.; Batha, S. H. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States); Clark, D. S.; Hammel, B. A.; Milovich, J. L.; Salmonson, J. D.; Kozioziemski, B. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

2014-09-15

Beryllium ablators offer higher ablation velocity, rate, and pressure than their carbon-based counterparts, with the potential to increase the probability of achieving ignition at the National Ignition Facility (NIF) [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)]. We present here a detailed hydrodynamic stability analysis of low (NIF Revision 6.1) and high adiabat NIF beryllium target designs. Our targets are optimized to fully utilize the advantages of beryllium in order to suppress the growth of hydrodynamic instabilities. This results in an implosion that resists breakup of the capsule, and simultaneously minimizes the amount of ablator material mixed into the fuel. We quantify the improvement in stability of beryllium targets relative to plastic ones, and show that a low adiabat beryllium capsule can be at least as stable at the ablation front as a high adiabat plastic target.

The Crystal Backlighter Imager: a spherically-bent crystal imager for radiography on the National Ignition Facility

Science.gov (United States)

Hall, Gareth; Krauland, Christine; Buscho, Justin; Hibbard, Robin; McCarville, Thomas; Lowe-Webb, Roger; Ayers, Shannon; Kalantar, Daniel; Kohut, Thomas; Kemp, G. Elijah; Bradley, David; Bell, Perry; Landen, Otto; Brewster, Nathaniel; Piston, Kenneth

2017-10-01

The Crystal Backlighter Imager (CBI) is a quasi-monochromatic, near-normal incidence, spherically-bent crystal imager being developed for the NIF, which will allow ICF capsule implosions to be radiographed close to stagnation for the first time. This has not been possible using the previous pinhole-based area-backlighter configuration, as the self-emission from the capsule hotspot overwhelms the backlighter in the final stages of the implosion. CBI mitigates the broadband self-emission from the capsule hot spot by using the extremely narrow bandwidth (a few eV) inherent to imagers based on near-normal-incidence Bragg x-ray optics. The development of a diagnostic with the capability to image the capsule during the final stages of the implosion (r less than 200um) is important, as it will allow the shape, integrity and density of the shell to be measured, and will allow the evolution of features, such as the fill tube and capsule support structure, to be imaged close to bang time. The concept and operation of the 11.6keV CBI diagnostic will be discussed, and the first results from experiments on the NIF will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344.

Hydrodynamic instability growth and mix experiments at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Smalyuk, V. A.; Barrios, M.; Caggiano, J. A.; Casey, D. T.; Cerjan, C. J.; Clark, D. S.; Edwards, M. J.; Haan, S. W.; Hammel, B. A.; Hamza, A.; Hsing, W. W.; Hurricane, O.; Kroll, J.; Landen, O. L.; Lindl, J. D.; Ma, T.; McNaney, J. M.; Mintz, M.; Parham, T.; Peterson, J. L. [Lawrence Livermore National Laboratory, NIF Directorate, Livermore, California 94550 (United States); and others

2014-05-15

Hydrodynamic instability growth and its effects on implosion performance were studied at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)]. Implosion performance and mix have been measured at peak compression using plastic shells filled with tritium gas and containing embedded localized carbon-deuterium diagnostic layers in various locations in the ablator. Neutron yield and ion temperature of the deuterium-tritium fusion reactions were used as a measure of shell-gas mix, while neutron yield of the tritium-tritium fusion reaction was used as a measure of implosion performance. The results have indicated that the low-mode hydrodynamic instabilities due to surface roughness were the primary culprits for yield degradation, with atomic ablator-gas mix playing a secondary role. In addition, spherical shells with pre-imposed 2D modulations were used to measure instability growth in the acceleration phase of the implosions. The capsules were imploded using ignition-relevant laser pulses, and ablation-front modulation growth was measured using x-ray radiography for a shell convergence ratio of ∼2. The measured growth was in good agreement with that predicted, thus validating simulations for the fastest growing modulations with mode numbers up to 90 in the acceleration phase. Future experiments will be focused on measurements at higher convergence, higher-mode number modulations, and growth occurring during the deceleration phase.

Explosive-driven hemispherical implosions for generating fusion plasmas

International Nuclear Information System (INIS)

Sagie, D.; Glass, I.I.

1982-03-01

The UTIAS explosive-driven-implosion facility was used to produce stable, centered and focussed hemispherical implosions to generate neutrons from D-D reactions. A high resolution scintillator-detection system measured the neutrons and γ-rays resulting from the fusion of deuterium. Several approaches were used to initiate fusion in deuterium. The simplest and most direct proved to be in a predetonated stoichiometric mixture of deuterium-oxygen. The other successful method was a miniature Voitenko-type compressor where a plane diaphragm was driven by the implosion wave into a secondary small spherical cavity that contained pure deuterium gas at one atmosphere. A great deal of work still remains in order to measure accurately the neutron flux and its velocity distribution as well as the precise interactions of the neturons with the steel chamber which produced the γ-rays. Nevertheless, this is the only known work where fusion neutrons were produced by chemical energy only in a direct and indirect manner

Convergent ablation measurements of plastic ablators in gas-filled rugby hohlraums on OMEGA

Science.gov (United States)

Casner, A.; Jalinaud, T.; Masse, L.; Galmiche, D.

2015-10-01

Indirect-drive implosions experiments were conducted on the Omega Laser Facility to test the performance of uniformly doped plastic ablators for Inertial Confinement Fusion. The first convergent ablation measurements in gas-filled rugby hohlraums are reported. Ignition relevant limb velocities in the range from 150 to 300 μm .n s-1 have been reached by varying the laser drive energy and the initial capsule aspect ratio. The measured capsule trajectory and implosion velocity are in good agreement with 2D integrated simulations and a zero-dimensional modeling of the implosions. We demonstrate experimentally the scaling law for the maximum implosion velocity predicted by the improved rocket model [Y. Saillard, Nucl. Fusion 46, 1017 (2006)] in the high-ablation regime case.

Numerical simulation of wire array load implosion on Yang accelerator

International Nuclear Information System (INIS)

Zhao Hailong; Deng Jianjun; Wang Qiang; Zou Wenkang; Wang Ganghua

2012-01-01

Based on the ZORK model describing the Saturn facility, a zero dimensional load model of the wire array Z-pinch on Yang accelerator is designed using Pspice to simulate the implosion process. Comparisons between the calculated results and experimental data prove the load model to be correct. The applicability and shortcomings of the load model are presented. One-dimensional magnetohydrodynamic calculations are performed by using the current curve obtained from calculated results of experiment Yang 1050#. and the parameters such as implosion time and radiation X-ray power are obtained. (authors)

Convergent ablation measurements with gas-filled rugby hohlraum on OMEGA

Science.gov (United States)

Casner, A.; Jalinaud, T.; Galmiche, D.

2016-03-01

Convergent ablation experiments with gas-filled rugby hohlraum were performed for the first time on the OMEGA laser facility. A time resolved 1D streaked radiography of capsule implosion is acquired in the direction perpendicular to hohlraum axis, whereas a 2D gated radiography is acquired at the same time along the hohlraum axis on a x-ray framing camera. The implosion trajectory has been measured for various kinds of uniformly doped ablators, including germanium-doped and silicon-doped polymers (CH), at two different doping fraction (2% and 4% at.). Our experiments aimed also at measuring the implosion performance of laminated capsules. A laminated ablator is constituted by thin alternate layers of un-doped and doped CH. It has been previously shown in planar geometry that laminated ablators could mitigate Rayleigh Taylor growth at ablation front. Our results confirm that the implosion of a capsule constituted with a uniform or laminated ablator behaves similarly, in accordance with post-shot simulations performed with the CEA hydrocode FCI2.

Indirect (x-ray) irradiation of encapsulated microtargets in the Iskra-5 facility

International Nuclear Information System (INIS)

Abzaev, F.M.; Bel'kov, S.A.; Bessarab, A.V.; Bondarenko, S.V.; Gaidash, V.A.; Garanin, S.G.; Dolgoleva, G.V.; Zhidkov, N.V.; Izgorodin, V.M.; Kirillov, G.A.; Kochemasov, G.G.; Litvin, D.N.; Martynenko, S.P.; Murugov, V.M.; Mkhitar'yan, L.S.; Pinegin, A.V.; Petrov, S.I.; Senik, A.V.; Suslov, N.A.; Bushuev, V.S.

1998-01-01

Experiments on the indirect (x-ray) irradiation of high-aspect-ratio capsules (with a diameter-to-thickness ratio ≅900) filled with DT gas are performed on the Iskra-5 laser facility. It is shown that all the characteristics measured (neutron yield, ion temperature, shell implosion time, etc.) are faithfully reproduced in calculations based on the one-dimensional SNDA (spectral nonequilibrium diffusion of absorption) program for nonequilibrium radiation gas dynamics. The calculations provide an explanation for the experimentally detected generation of a smaller number of neutrons in an experiment with a higher measured value for the ion temperature of DT gas

Simple spherical ablative-implosion model

International Nuclear Information System (INIS)

Mayer, F.J.; Steele, J.T.; Larsen, J.T.

1980-01-01

A simple model of the ablative implosion of a high-aspect-ratio (shell radius to shell thickness ratio) spherical shell is described. The model is similar in spirit to Rosenbluth's snowplow model. The scaling of the implosion time was determined in terms of the ablation pressure and the shell parameters such as diameter, wall thickness, and shell density, and compared these to complete hydrodynamic code calculations. The energy transfer efficiency from ablation pressure to shell implosion kinetic energy was examined and found to be very efficient. It may be possible to attach a simple heat-transport calculation to our implosion model to describe the laser-driven ablation-implosion process. The model may be useful for determining other energy driven (e.g., ion beam) implosion scaling

Development of the CD Symcap platform to study gas-shell mix in implosions at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Casey, D. T.; Smalyuk, V. A.; Tipton, R. E.; Pino, J. E.; Remington, B. A.; Rowley, D. P.; Weber, S. V.; Barrios, M.; Benedetti, L. R.; Bleuel, D. L.; Bond, E. J.; Bradley, D. K.; Caggiano, J. A.; Callahan, D. A.; Cerjan, C. J.; Edwards, M. J.; Fittinghoff, D.; Glenn, S.; Haan, S. W.; Hamza, A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2014-09-15

Surrogate implosions play an important role at the National Ignition Facility (NIF) for isolating aspects of the complex physical processes associated with fully integrated ignition experiments. The newly developed CD Symcap platform has been designed to study gas-shell mix in indirectly driven, pure T{sub 2}-gas filled CH-shell implosions equipped with 4 μm thick CD layers. This configuration provides a direct nuclear signature of mix as the DT yield (above a characterized D contamination background) is produced by D from the CD layer in the shell, mixing into the T-gas core. The CD layer can be placed at different locations within the CH shell to probe the depth and extent of mix. CD layers placed flush with the gas-shell interface and recessed up to 8 μm have shown that most of the mix occurs at the inner-shell surface. In addition, time-gated x-ray images of the hotspot show large brightly radiating objects traversing through the hotspot around bang-time, which are likely chunks of CH/CD plastic. This platform is a powerful new capability at the NIF for understanding mix, one of the key performance issues for ignition experiments.

ICF ignition capsule neutron, gamma ray, and high energy x-ray images

Science.gov (United States)

Bradley, P. A.; Wilson, D. C.; Swenson, F. J.; Morgan, G. L.

2003-03-01

Post-processed total neutron, RIF neutron, gamma-ray, and x-ray images from 2D LASNEX calculations of burning ignition capsules are presented. The capsules have yields ranging from tens of kilojoules (failures) to over 16 MJ (ignition), and their implosion symmetry ranges from prolate (flattest at the hohlraum equator) to oblate (flattest towards the laser entrance hole). The simulated total neutron images emphasize regions of high DT density and temperature; the reaction-in-flight neutrons emphasize regions of high DT density; the gamma rays emphasize regions of high shell density; and the high energy x rays (>10 keV) emphasize regions of high temperature.

Specific features of implosion of metallized fiber arrays

Energy Technology Data Exchange (ETDEWEB)

Mitrofanov, K. N., E-mail: mitrofan@triniti.ru; Aleksandrov, V. V.; Gritsuk, A. N.; Grabovski, E. V.; Frolov, I. N.; Laukhin, Ya. N.; Breshkov, S. S. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2017-02-15

Implosion of metallized fiber arrays was studied experimentally at the Angara-5-1 facility. The use of such arrays makes it possible to investigate the production and implosion dynamics of plasmas of various metals (such as tin, indium, and bismuth) that were previously unavailable for such studies. The plasma production rates m-dot (in μg/(cm{sup 2} ns)) for different metals were determined and quantitatively compared. Varying the thickness of the metal layer deposited on kapron fibers (the total linear mass of the metal coating being maintained at the level of 220 μg/cm), the current and velocity of the plasma precursor were studied as functions of the thickness of the metal coating. The strong difference in the rates of plasma production from the metal coating and kapron fibers results in the redistribution of the discharge current between the Z-pinch and the trailing fiber plasma. The outer boundary of the plasma produced from the metal coating is found to be stable against instabilities typical of the final stage of implosion of conventional wire arrays.

Polyimide capsules may hold high pressure DT fuel without cryogenic support for the National Ignition Facility indirect-drive targets

International Nuclear Information System (INIS)

Sanchez, J.J.; Letts, S.A.

1997-01-01

New target designs for the Omega upgrade laser and ignition targets in the National Ignition Facility (NIF) require thick (80 - 100 microm) cryogenic fuel layers. The Omega upgrade target will require cryogenic handling after initial fill because of the high fill pressures and the thin capsule walls. For the NIF indirectly driven targets, a larger capsule size and new materials offer hope that they can be built, filled and stored in a manner similar to the targets used in the Nova facility without requiring cryogenic handling

Improving hot-spot pressure for ignition in high-adiabat Inertial Confinement Fusion implosion

OpenAIRE

Kang, Dongguo; Zhu, Shaoping; Pei, Wenbing; Zou, Shiyang; Zheng, Wudi; Gu, Jianfa; Dai, Zhensheng

2017-01-01

A novel capsule target design to improve the hot-spot pressure in the high-adiabat implosion for inertial confinement fusion is proposed, where a layer of comparatively high-density material is used as a pusher between the fuel and the ablator. This design is based on our theoretical finding of the stagnation scaling laws, which indicates that the hot spot pressure can be improved by increasing the kinetic energy density $\\rho_d V_{imp}^2/2$ ($\\rho_d$ is the shell density when the maximum she...

Evaulation of B4C as an ablator material for NIF capsules. Revision 1

International Nuclear Information System (INIS)

Burnham, A.K.; Alford, C.S.; Makowiecki, D.M.; Dittrich, T.R.; Wallace, R.J.; Honea, E.C.; King, C.M.; Steinman, D.

1997-01-01

Boron carbide (B 4 C) is examined as a potential fuel container and ablator for implosion capsules on the National Ignition Facility (NIF). A capsule of pure B 4 C encasing a layer of solid DT implodes stably and ignites with anticipated NIF x-ray drives, producing 18 MJ of energy. Thin films of B 4 C were found to be resistant to oxidation and modestly transmitting in the infrared (IR), possibly enabling IR fuel characterization and enhancement for thin permeation barriers but not for full-thickness capsules. Polystyrene mandrels 0.5 mm in diameter were successfully coated with 0.15-2.0 micrometers of B 4 C. Thickness estimated from optical density agreed well with those measured by scanning electron microscopy (SEM). The B 4 C microstructure was columnar but finer than for Be made at the same conditions. B 4 C is a very strong material, with a fiber tensile strength capable of holding NIF fill pressures at room temperature, but it is also very brittle, and microscopic flaws or grain structure may limit the noncryogenic fill pressure. Argon (Ar) permeation rates were measured for a few capsules that had been further coated with 5 micrometers of plasma polymer. The B 4 C coatings tended to crack under tensile load. Some shells filled more slowly than they leaked, suggesting that the cracks open and close under opposite pressure loading. As observed earlier for Ti coatings, 0.15-micrometer layers of B 4 C had better gas retention properties than 2-micrometer layers, possibly because of fewer cracks. Permeation and fill strength issues for capsules with a full ablator thickness of B 4 C are unresolved. 21 refs., 6 figs

Yield degradation in inertial-confinement-fusion implosions due to shock-driven kinetic fuel-species stratification and viscous heating

Science.gov (United States)

Taitano, W. T.; Simakov, A. N.; Chacón, L.; Keenan, B.

2018-05-01

Anomalous thermonuclear yield degradation (i.e., that not describable by single-fluid radiation hydrodynamics) in Inertial Confinement Fusion (ICF) implosions is ubiquitously observed in both Omega and National Ignition experiments. Multiple experimental and theoretical studies have been carried out to investigate the origin of such a degradation. Relative concentration changes of fuel-ion species, as well as kinetically enhanced viscous heating, have been among possible explanations proposed for certain classes of ICF experiments. In this study, we investigate the role of such kinetic plasma effects in detail. To this end, we use the iFP code to perform multi-species ion Vlasov-Fokker-Planck simulations of ICF capsule implosions with the fuel comprising various hydrodynamically equivalent mixtures of deuterium (D) and helium-3 (3He), as in the original Rygg experiments [J. R. Rygg et al., Phys. Plasmas 13, 052702 (2006)]. We employ the same computational setup as in O. Larroche [Phys. Plasmas 19, 122706 (2012)], which was the first to simulate the experiments kinetically. However, unlike the Larroche study, and in partial agreement with experimental data, we find a systematic yield degradation in multi-species simulations versus averaged-ion simulations when the D-fuel fraction is decreased. This yield degradation originates in the fuel-ion species stratification induced by plasma shocks, which imprints the imploding system and results in the relocation of the D ions from the core of the capsule to its periphery, thereby reducing the yield relative to a non-separable averaged-ion case. By comparing yields from the averaged-ion kinetic simulations and from the hydrodynamic scaling, we also observe yield variations associated with ion kinetic effects other than fuel-ion stratification, such as ion viscous heating, which is typically neglected in hydrodynamic implosions' simulations. Since our kinetic simulations are driven by hydrodynamic boundary conditions at the

High Foot Implosion Experiments in Rugby Hohlraums

Science.gov (United States)

Ralph, Joseph; Leidinger, J.-P.; Callahan, D.; Kaiser, P.; Morice, O.; Marion, D.; Moody, J. D.; Ross, J. S.; Amendt, P.; Kritcher, A. L.; Milovich, J. L.; Strozzi, D.; Hinkel, D.; Michel, P.; Berzak Hopkins, L.; Pak, A.; Dewald, E. L.; Divol, L.; Khan, S.; Rygg, R.; Hurricane, O.; Lawrence Livermore National Lab Team; CEA/DAM Team

2015-11-01

The rugby hohlraum design is aimed at providing uniform x-ray drive on the capsule while minimizing the need for crossed beam energy transfer (CBET). As part of a series of experiments at the NIF using rugby hohlraums, design improvements in dual axis shock tuning experiments produced some of the most symmetric shocks measured on implosion experiments at the NIF. Additionally, tuning of the in-flight shell and hot spot shape have demonstrated that capsules can be tuned between oblate and prolate with measured velocities of nearly 340 km/s. However, these experimental measurements were accompanied by high levels of Stimulated Raman Scattering (SRS) that may result from the long inner beam path length, reamplification of the inner SRS by the outers, significant (CBET) or a combination of these. All rugby shots results were achieved with lower levels of hot electrons that can preheat the DT fuel layer for increased adiabat and reduced areal density. Detailed results from these experiments and those planned throughout the summer will be presented and compared with results obtained from cylindrical hohlraums. This work performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Lab under Contract DE-AC52-07NA27344.

Stability analysis of directly driven Nif capsules

Energy Technology Data Exchange (ETDEWEB)

Goncharov, V.N.; Skupsky, S.; McKenty, P.W.; Delettrez, J.A.; Town, R.P.J. [Rochester Univ., NY (United States). Lab. for Laser Energetics; Cherfils-Clerouin, C. [CEA/DAM-Ile de France, DIF, 91 - Bruyeres Le Chatel (France)

2000-07-01

An analytical model is presented to study perturbation evolution at the ablation and inner surfaces of the imploding shell. The model describes the ablative Rayleigh-Taylor and Bell-Plesset instabilities. The initial conditions for the model are determined by using existing theories of laser imprint, ablative Richtmyer-Meshkov instability, 'feed-out' and by performing a series of 2-D ORCHID simulations. The model and simulations show that the direct-drive cryogenic {alpha} = 3 NIF capsules remain intact during the implosion if laser nonuniformities are smoothed by 2-D SSD used in the current direct-drive target designs. (authors)

Wavelength-detuning cross-beam energy transfer mitigation scheme for direct drive: Modeling and evidence from National Ignition Facility implosions

Science.gov (United States)

Marozas, J. A.; Hohenberger, M.; Rosenberg, M. J.; Turnbull, D.; Collins, T. J. B.; Radha, P. B.; McKenty, P. W.; Zuegel, J. D.; Marshall, F. J.; Regan, S. P.; Sangster, T. C.; Seka, W.; Campbell, E. M.; Goncharov, V. N.; Bowers, M. W.; Di Nicola, J.-M. G.; Erbert, G.; MacGowan, B. J.; Pelz, L. J.; Moody, J.; Yang, S. T.

2018-05-01

Cross-beam energy transfer (CBET) results from two-beam energy exchange via seeded stimulated Brillouin scattering, which detrimentally reduces laser-energy absorption for direct-drive inertial confinement fusion. Consequently, ablation pressure and implosion velocity suffer from the decreased absorption, reducing target performance in both symmetric and polar direct drive. Additionally, CBET alters the time-resolved scattered-light spectra and redistributes absorbed and scattered-light-changing shell morphology and low-mode drive symmetry. Mitigating CBET is demonstrated in inertial confinement implosions at the National Ignition Facility by detuning the laser-source wavelengths (±2.3 Å UV) of the interacting beams. In polar direct drive, wavelength detuning was shown to increase the equatorial region velocity experimentally by 16% and to alter the in-flight shell morphology. These experimental observations are consistent with design predictions of radiation-hydrodynamic simulations that indicate a 10% increase in the average ablation pressure. These results indicate that wavelength detuning successfully mitigates CBET. Simulations predict that optimized phase plates and wavelength-detuning CBET mitigation utilizing the three-legged beam layout of the OMEGA Laser System significantly increase absorption and achieve >100-Gbar hot-spot pressures in symmetric direct drive.

Convergent ablation measurements with gas-filled rugby hohlraum on OMEGA

International Nuclear Information System (INIS)

Casner, A.; Jalinaud, T.; Galmiche, D.

2016-01-01

Convergent ablation experiments with gas-filled rugby hohlraum were performed for the first time on the OMEGA laser facility. A time resolved 1D streaked radiography of capsule implosion is acquired in the direction perpendicular to hohlraum axis, whereas a 2D gated radiography is acquired at the same time along the hohlraum axis on a x-ray framing camera. The implosion trajectory has been measured for various kinds of uniformly doped ablators, including germanium-doped and silicon-doped polymers (CH), at two different doping fraction (2% and 4% at.). Our experiments aimed also at measuring the implosion performance of laminated capsules. A laminated ablator is constituted by thin alternate layers of un-doped and doped CH. It has been previously shown in planar geometry that laminated ablators could mitigate Rayleigh Taylor growth at ablation front. Our results confirm that the implosion of a capsule constituted with a uniform or laminated ablator behaves similarly, in accordance with post-shot simulations performed with the CEA hydrocode FCI2. (paper)

Short-wavelength and three-dimensional instability evolution in National Ignition Facility ignition capsule designs

International Nuclear Information System (INIS)

Clark, D. S.; Haan, S. W.; Cook, A. W.; Edwards, M. J.; Hammel, B. A.; Koning, J. M.; Marinak, M. M.

2011-01-01

Ignition capsule designs for the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)] have continued to evolve in light of improved physical data inputs, improving simulation techniques, and, most recently, experimental data from a growing number of NIF sub-ignition experiments. This paper summarizes a number of recent changes to the cryogenic capsule design and some of our latest techniques in simulating its performance. Specifically, recent experimental results indicated harder x-ray drive spectra in NIF hohlraums than were predicted and used in previous capsule optimization studies. To accommodate this harder drive spectrum, a series of high-resolution 2-D simulations, resolving Legendre mode numbers as high as 2000, were run and the germanium dopant concentration and ablator shell thicknesses re-optimized accordingly. Simultaneously, the possibility of cooperative or nonlinear interaction between neighboring ablator surface defects has motivated a series of fully 3-D simulations run with the massively parallel HYDRA code. These last simulations include perturbations seeded on all capsule interfaces and can use actual measured shell surfaces as initial conditions. 3-D simulations resolving Legendre modes up to 200 on large capsule sectors have run through ignition and burn, and higher resolution simulations resolving as high as mode 1200 have been run to benchmark high-resolution 2-D runs. Finally, highly resolved 3-D simulations have also been run of the jet-type perturbation caused by the fill tube fitted to the capsule. These 3-D simulations compare well with the more typical 2-D simulations used in assessing the fill tube's impact on ignition. Coupled with the latest experimental inputs from NIF, our improving simulation capability yields a fuller and more accurate picture of NIF ignition capsule performance.

Hot cell examination on the surveillance capsule and HANARO capsule in IMEF

International Nuclear Information System (INIS)

Choo, Yong Sun; Oh, Wan Ho; Yoo, Byung Ok; Jung, Yang Hong; Ahn, Sang Bok; Baik, Seung Je; Song, Wung Sup; Hong, Kwon Pyo

2000-01-01

For the maintenance of integrity and safety of pressurizer of commercial power plant until its life span, it is required by US NRC 10CFR50 APP. G and H and ASTM E185-94 to periodically monitor irradiation embrittlement by neutron irradiation. In order to accomplished the requirement reactor operator has been carrying out the test by extracting the monitoring capsule embeded in reactor during the period of planned preventive maintenance. In relation to this irradiation samples are being used for prediction of reactor vessel life span and reactor vessel's adjusted reference temperature by irradiation of neutron flux enough to reach to end of life span. And also irradiation capsules with and without instrumentation are used for R and D on nuclear materials. Each capsule contains high radioactivity, therefore, post irradiation examination has to be handled by all means in the hot cell. The facility available for this purpose is Irradiated material examination facility (IMEF) to handle such works as capsule receiving, capsule cut and dismantling, sample classification, various examination, and finally development and improvement of examination equipment and instrumentation. (Hong, J. S.)

High performance capsule implosions driven by the Z-pinch dynamic hohlraum

Energy Technology Data Exchange (ETDEWEB)

Rochau, G A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Bailey, J E [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Chandler, G A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Cooper, G [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Dunham, G S [K-tech Corporation, 10800 Gibson S E, Albuquerque, NM 87123 (United States); Lake, P W [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Leeper, R J [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Lemke, R W [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Mehlhorn, T A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Nikroo, A [General Atomics, PO Box 85608, San Diego, CA 92186 (United States); Peterson, K J [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Ruiz, C L [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Schroen, D G [General Atomics, PO Box 85608, San Diego, CA 92186 (United States); Slutz, S A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Steinman, D [General Atomics, PO Box 85608, San Diego, CA 92186 (United States); Stygar, W A [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States); Varnum, W [Sandia National Laboratories, PO Box 5800 MS 1196, Albuquerque, NM 87185 (United States)

2007-12-15

The Z-pinch dynamic hohlraum (ZPDH) is a high-power x-ray source that has been used in a variety of high energy-density experiments including inertial confinement fusion (ICF) studies. The system consists of a tungsten wire-array Z pinch that implodes onto a low-density CH{sub 2} foam converter launching a radiating shock that heats the hohlraum to radiation temperatures >200 eV. Through time-gated pinhole camera measurements, the mean shock speed is measured from 28 experiments to be 326 {+-} 4 {mu}m ns{sup -1} with a shot-to-shot standard deviation of 7%. Broad-band x-ray measurements indicate that the shot-to-shot reproducibility in the power emission and pulse-shape of the source shock is <15% and {approx}5%, respectively. Calculations have shown that an ICF capsule placed at the center of the foam in the ZPDH can absorb >40 kJ of x-ray energy, within a factor of 4 of the energy believed sufficient for ICF ignition. The capsule types imploded by the ZPDH have evolved over four years culminating in a design that produces record indirect-drive DD thermonuclear neutron yields of up to 3.5E11.

Optimized beryllium target design for indirectly driven inertial confinement fusion experiments on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Simakov, Andrei N., E-mail: simakov@lanl.gov; Wilson, Douglas C.; Yi, Sunghwan A.; Kline, John L.; Batha, Steven H. [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States); Clark, Daniel S.; Milovich, Jose L.; Salmonson, Jay D. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

2014-02-15

For indirect drive inertial confinement fusion, Beryllium (Be) ablators offer a number of important advantages as compared with other ablator materials, e.g., plastic and high density carbon. In particular, the low opacity and relatively high density of Be lead to higher rocket efficiencies giving a higher fuel implosion velocity for a given X-ray drive; and to higher ablation velocities providing more ablative stabilization and reducing the effect of hydrodynamic instabilities on the implosion performance. Be ablator advantages provide a larger target design optimization space and can significantly improve the National Ignition Facility (NIF) [J. D. Lindl et al., Phys. Plasmas 11, 339 (2004)] ignition margin. Herein, we summarize the Be advantages, briefly review NIF Be target history, and present a modern, optimized, low adiabat, Revision 6 NIF Be target design. This design takes advantage of knowledge gained from recent NIF experiments, including more realistic levels of laser-plasma energy backscatter, degraded hohlraum-capsule coupling, and the presence of cross-beam energy transfer.

Sensitivity of Inferred Electron Temperature from X-ray Emission of NIF Cryogenic DT Implosions

Energy Technology Data Exchange (ETDEWEB)

Klem, Michael [Univ. of Dallas, Irving, TX (United States)

2015-05-01

The National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory seeks to achieve thermonuclear ignition through inertial confinement fusion. The accurate assessment of the performance of each implosion experiment is a crucial step. Here we report on work to derive a reliable electron temperature for the cryogenic deuteriumtritium implosions completed on the NIF using the xray signal from the Ross filter diagnostic. These Xrays are dominated by bremsstrahlung emission. By fitting the xray signal measured through each of the individual Ross filters, the source bremsstrahlung spectrum can be inferred, and an electron temperature of the implosion hot spot inferred. Currently, each filter is weighted equally in this analysis. We present work quantifying the errors with such a technique and the results from investigating the contribution of each filter to the overall accuracy of the temperature inference. Using this research, we also compare the inferred electron temperature against other measured implosion quantities to develop a more complete understanding of the hotspot physics.

Early time implosion symmetry from two-axis shock-timing measurements on indirect drive NIF experiments

Energy Technology Data Exchange (ETDEWEB)

Moody, J. D., E-mail: moody4@llnl.gov; Robey, H. F.; Celliers, P. M.; Munro, D. H.; Barker, D. A.; Baker, K. L.; Döppner, T.; Hash, N. L.; Berzak Hopkins, L.; LaFortune, K.; Landen, O. L.; LePape, S.; MacGowan, B. J.; Ralph, J. E.; Ross, J. S.; Widmayer, C. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Nikroo, A.; Giraldez, E. [General Atomics, San Diego, California 92186-5608 (United States); Boehly, T. [Laboratory for Laser Energetics, Rochester, New York 14623-1299 (United States)

2014-09-15

An innovative technique has been developed and used to measure the shock propagation speed along two orthogonal axes in an inertial confinement fusion indirect drive implosion target. This development builds on an existing target and diagnostic platform for measuring the shock propagation along a single axis. A 0.4 mm square aluminum mirror is installed in the ablator capsule which adds a second orthogonal view of the x-ray-driven shock speeds. The new technique adds capability for symmetry control along two directions of the shocks launched in the ablator by the laser-generated hohlraum x-ray flux. Laser power adjustments in four different azimuthal cones based on the results of this measurement can reduce time-dependent symmetry swings during the implosion. Analysis of a large data set provides experimental sensitivities of the shock parameters to the overall laser delivery and in some cases shows the effects of laser asymmetries on the pole and equator shock measurements.

Investigation of ion kinetic effects in direct-drive exploding-pusher implosions at the NIF

Energy Technology Data Exchange (ETDEWEB)

Rosenberg, M. J., E-mail: mrosenbe@mit.edu; Zylstra, A. B.; Séguin, F. H.; Rinderknecht, H. G.; Frenje, J. A.; Gatu Johnson, M.; Sio, H.; Waugh, C. J.; Sinenian, N.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); McKenty, P. W.; Hohenberger, M.; Radha, P. B.; Delettrez, J. A.; Glebov, V. Yu.; Betti, R.; Goncharov, V. N.; Knauer, J. P.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others

2014-12-15

Measurements of yield, ion temperature, areal density (ρR), shell convergence, and bang time have been obtained in shock-driven, D{sub 2} and D{sup 3}He gas-filled “exploding-pusher” inertial confinement fusion (ICF) implosions at the National Ignition Facility to assess the impact of ion kinetic effects. These measurements probed the shock convergence phase of ICF implosions, a critical stage in hot-spot ignition experiments. The data complement previous studies of kinetic effects in shock-driven implosions. Ion temperature and fuel ρR inferred from fusion-product spectroscopy are used to estimate the ion-ion mean free path in the gas. A trend of decreasing yields relative to the predictions of 2D DRACO hydrodynamics simulations with increasing Knudsen number (the ratio of ion-ion mean free path to minimum shell radius) suggests that ion kinetic effects are increasingly impacting the hot fuel region, in general agreement with previous results. The long mean free path conditions giving rise to ion kinetic effects in the gas are often prevalent during the shock phase of both exploding pushers and ablatively driven implosions, including ignition-relevant implosions.

A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions

International Nuclear Information System (INIS)

Liu, Dongxiao; Shan, Lianqiang; Zhou, Weimin; Wu, Yuchi; Zhu, Bin; Zhang, Feng; Bi, Bi; Zhang, Bo; Zhang, Zhimeng; Shui, Min; He, Yingling; Gu, Yuqiu; Zhang, Baohan; Peng, Xiaoshi; Xu, Tao; Wang, Feng; Yang, Zhiwen; Chen, Tao; Chen, Li; Chen, Ming

2016-01-01

During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.

A simple method to prevent hard X-ray-induced preheating effects inside the cone tip in indirect-drive fast ignition implosions

Energy Technology Data Exchange (ETDEWEB)

Liu, Dongxiao; Shan, Lianqiang; Zhou, Weimin; Wu, Yuchi; Zhu, Bin; Zhang, Feng; Bi, Bi; Zhang, Bo; Zhang, Zhimeng; Shui, Min; He, Yingling; Gu, Yuqiu, E-mail: yqgu@caep.cn; Zhang, Baohan [Science and Technology on Plasma Physics Laboratory, China Academy of Engineering Physics, Mianyang 621900 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Peng, Xiaoshi; Xu, Tao; Wang, Feng; Yang, Zhiwen; Chen, Tao; Chen, Li; Chen, Ming [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); and others

2016-06-15

During fast-ignition implosions, preheating of inside the cone tip caused by hard X-rays can strongly affect the generation and transport of hot electrons in the cone. Although indirect-drive implosions have a higher implosion symmetry, they cause stronger preheating effects than direct-drive implosions. To control the preheating of the cone tip, we propose the use of indirect-drive fast-ignition targets with thicker tips. Experiments carried out at the ShenGuang-III prototype laser facility confirmed that thicker tips are effective for controlling preheating. Moreover, these results were consistent with those of 1D radiation hydrodynamic simulations.

Hot spot mix in ICF implosions on the NIF

Science.gov (United States)

Ma, Tammy

2016-10-01

In the quest to achieve ignition through the inertial confinement fusion scheme, one of the critical challenges is to drive a symmetric implosion at high velocity without hydrodynamic instabilities becoming detrimental. These instabilities, primarily at the ablation front and the fuel-ablator interface, can cause mix of the higher-Z shell into the hot spot, resulting in increased radiation loss and thus reduced temperature and neutron yield. To quantify the level of mix, we developed a model that infers the level of hot spot contamination using the ratio of the enhanced x-ray production relative to the neutron yield. Applying this methodology to the full ensemble of indirect-drive National Ignition Facility (NIF) cryogenically layered DT implosions provides insight on the sensitivity of performance to the level of ablator-hot spot mix. In particular, the improvement seen with the High Foot design can be primarily attributed to a reduction in ablation-front instability mix that enabled the implosions to be pushed to higher velocity and performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, Lawrence Livermore National Security, LLC.

Conceptual design of initial opacity experiments on the national ignition facility

Science.gov (United States)

Heeter, R. F.; Bailey, J. E.; Craxton, R. S.; Devolder, B. G.; Dodd, E. S.; Garcia, E. M.; Huffman, E. J.; Iglesias, C. A.; King, J. A.; Kline, J. L.; Liedahl, D. A.; McKenty, P. W.; Opachich, Y. P.; Rochau, G. A.; Ross, P. W.; Schneider, M. B.; Sherrill, M. E.; Wilson, B. G.; Zhang, R.; Perry, T. S.

2017-02-01

Accurate models of X-ray absorption and re-emission in partly stripped ions are necessary to calculate the structure of stars, the performance of hohlraums for inertial confinement fusion and many other systems in high-energy-density plasma physics. Despite theoretical progress, a persistent discrepancy exists with recent experiments at the Sandia Z facility studying iron in conditions characteristic of the solar radiative-convective transition region. The increased iron opacity measured at Z could help resolve a longstanding issue with the standard solar model, but requires a radical departure for opacity theory. To replicate the Z measurements, an opacity experiment has been designed for the National Facility (NIF). The design uses established techniques scaled to NIF. A laser-heated hohlraum will produce X-ray-heated uniform iron plasmas in local thermodynamic equilibrium (LTE) at temperatures eV and electron densities 21~\\text{cm}-3$ . The iron will be probed using continuum X-rays emitted in a ps, diameter source from a 2 mm diameter polystyrene (CH) capsule implosion. In this design, of the NIF beams deliver 500 kJ to the mm diameter hohlraum, and the remaining directly drive the CH capsule with 200 kJ. Calculations indicate this capsule backlighter should outshine the iron sample, delivering a point-projection transmission opacity measurement to a time-integrated X-ray spectrometer viewing down the hohlraum axis. Preliminary experiments to develop the backlighter and hohlraum are underway, informing simulated measurements to guide the final design.

Reaction-in-flight neutrons as a signature for shell mixing in National Ignition Facility capsules

International Nuclear Information System (INIS)

Hayes, A. C.; Bradley, P. A.; Grim, G. P.; Jungman, Gerard; Wilhelmy, J. B.

2010-01-01

Analytic calculations and results from computational simulations are presented that suggest that reaction-in-flight (RIF) neutrons can be used to diagnose mixing of the ablator shell material into the fuel in deuterium-tritium (DT) capsules designed for the National Ignition Facility (NIF) [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)]. Such mixing processes in NIF capsules are of fundamental physical interest and can have important effects on capsule performance, quenching the total thermonuclear yield. The sensitivity of RIF neutrons to hydrodynamical mixing arises through the dependence of RIF production on charged-particle stopping lengths in the mixture of DT fuel and ablator material. Since the stopping power in the plasma is a sensitive function of the electron temperature and density, it is also sensitive to mix. RIF production scales approximately inversely with the degree of mixing taking place, and the ratio of RIF to down-scattered neutrons provides a measure of the mix fraction and/or the mixing length. For sufficiently high-yield capsules, where spatially resolved RIF images may be possible, neutron imaging could be used to map RIF images into detailed mix images.

Fire suppression as a thermal implosion

Science.gov (United States)

Novozhilov, Vasily

2017-01-01

The present paper discusses the possibility of the thermal implosion scenario. This process would be a reverse of the well known thermal explosion (autoignition) phenomenon. The mechanism for thermal implosion scenario is proposed which involves quick suppression of the turbulent diffusion flame. Classical concept of the thermal explosion is discussed first. Then a possible scenario for the reverse process (thermal implosion) is discussed and illustrated by a relevant mathematical model. Based on the arguments presented in the paper, thermal implosion may be observed as an unstable equilibrium point on the generalized Semenov diagram for turbulent flame, however this hypothesis requires ultimate experimental confirmation.

Self-Generated Magnetic Fields in the Stagnation Phase of Indirect-Drive Implosions on the National Ignition Facility

Science.gov (United States)

Walsh, C. A.; Chittenden, J. P.; McGlinchey, K.; Niasse, N. P. L.; Appelbe, B. D.

2017-04-01

Three-dimensional extended-magnetohydrodynamic simulations of the stagnation phase of inertial confinement fusion implosion experiments at the National Ignition Facility are presented, showing self-generated magnetic fields over 104 T . Angular high mode-number perturbations develop large magnetic fields, but are localized to the cold, dense hot-spot surface, which is hard to magnetize. When low-mode perturbations are also present, the magnetic fields are injected into the hot core, reaching significant magnetizations, with peak local thermal conductivity reductions greater than 90%. However, Righi-Leduc heat transport effectively cools the hot spot and lowers the neutron spectra-inferred ion temperatures compared to the unmagnetized case. The Nernst effect qualitatively changes the results by demagnetizing the hot-spot core, while increasing magnetizations at the edge and near regions of large heat loss.

Measuring implosion velocities in experiments and simulations of laser-driven cylindrical implosions on the OMEGA laser

Science.gov (United States)

Hansen, E. C.; Barnak, D. H.; Betti, R.; Campbell, E. M.; Chang, P.-Y.; Davies, J. R.; Glebov, V. Yu; Knauer, J. P.; Peebles, J.; Regan, S. P.; Sefkow, A. B.

2018-05-01

Laser-driven magnetized liner inertial fusion (MagLIF) on OMEGA involves cylindrical implosions, a preheat beam, and an applied magnetic field. Initial experiments excluded the preheat beam and magnetic field to better characterize the implosion. X-ray self-emission as measured by framing cameras was used to determine the shell trajectory. The 1D code LILAC was used to model the central region of the implosion, and results were compared to 2D simulations from the HYDRA code. Post-processing of simulation output with SPECT3D and Yorick produced synthetic x-ray images that were used to compare the simulation results with the x-ray framing camera data. Quantitative analysis shows that higher measured neutron yields correlate with higher implosion velocities. The future goal is to further analyze the x-ray images to characterize the uniformity of the implosions and apply these analysis techniques to integrated laser-driven MagLIF shots to better understand the effects of preheat and the magnetic field.

Early-time radiation flux symmetry optimization and its effect on gas-filled hohlraum ignition targets on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Milovich, J. L., E-mail: milovich1@llnl.gov; Dewald, E. L.; Pak, A.; Michel, P.; Town, R. P. J.; Bradley, D. K.; Landen, O.; Edwards, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2016-03-15

Achieving ignition on the National Ignition Facility (NIF) is tied to our ability to control and minimize deviations from sphericity of the capsule implosion. Low-mode asymmetries of the hot spot result from the combined effect of radiation drive asymmetries throughout the laser pulse and initial roughness on the capsule surface. In this paper, we report on simulations and experiments designed to assess, measure, and correct the drive asymmetries produced by the early-time (≈first 2 ns or “picket”) period of the laser pulse. The drive asymmetry during the picket is commonly thought to introduce distortions in the hot-spot shape at ignition time. However, a more subtle effect not previously considered is that it also leads to an asymmetry in shock velocity and timing, thereby increasing the fuel adiabat and reducing the margin for ignition. It is shown via hydrodynamic simulations that minimizing this effect requires that the early-time asymmetry be kept below 7.5% in the second Legendre mode (P{sub 2}), thus keeping the loss of performance margin below ≈10% for a layered implosion. Asymmetries during the picket of the laser pulse are measured using the instantaneous self-emission of a high-Z re-emission sphere in place of an ignition capsule in a hohlraum with large azimuthal diagnostic windows. Three dimensional simulations using the code HYDRA (to capture the effect of non-azimuthal hohlraum features) coupled to a cross-beam energy transfer model [Michel et al., Phys. Plasmas 17, 056305 (2010)] are used to establish the surrogacy of the re-emit target and to assess the early-time drive symmetry. Calculations using this model exhibit the same sensitivity to variations in the relative input powers between the different cones of NIF beams as measured for the “Rev5” CH target [Haan et al., Phys Plasmas 18, 051001 (2011)] and reported by Dewald et al. [Phys. Rev. Lett. 111, 235001 (2013)]. The same methodology applied to recently improved implosions

Early-time radiation flux symmetry optimization and its effect on gas-filled hohlraum ignition targets on the National Ignition Facility

International Nuclear Information System (INIS)

Milovich, J. L.; Dewald, E. L.; Pak, A.; Michel, P.; Town, R. P. J.; Bradley, D. K.; Landen, O.; Edwards, M. J.

2016-01-01

Achieving ignition on the National Ignition Facility (NIF) is tied to our ability to control and minimize deviations from sphericity of the capsule implosion. Low-mode asymmetries of the hot spot result from the combined effect of radiation drive asymmetries throughout the laser pulse and initial roughness on the capsule surface. In this paper, we report on simulations and experiments designed to assess, measure, and correct the drive asymmetries produced by the early-time (≈first 2 ns or “picket”) period of the laser pulse. The drive asymmetry during the picket is commonly thought to introduce distortions in the hot-spot shape at ignition time. However, a more subtle effect not previously considered is that it also leads to an asymmetry in shock velocity and timing, thereby increasing the fuel adiabat and reducing the margin for ignition. It is shown via hydrodynamic simulations that minimizing this effect requires that the early-time asymmetry be kept below 7.5% in the second Legendre mode (P_2), thus keeping the loss of performance margin below ≈10% for a layered implosion. Asymmetries during the picket of the laser pulse are measured using the instantaneous self-emission of a high-Z re-emission sphere in place of an ignition capsule in a hohlraum with large azimuthal diagnostic windows. Three dimensional simulations using the code HYDRA (to capture the effect of non-azimuthal hohlraum features) coupled to a cross-beam energy transfer model [Michel et al., Phys. Plasmas 17, 056305 (2010)] are used to establish the surrogacy of the re-emit target and to assess the early-time drive symmetry. Calculations using this model exhibit the same sensitivity to variations in the relative input powers between the different cones of NIF beams as measured for the “Rev5” CH target [Haan et al., Phys Plasmas 18, 051001 (2011)] and reported by Dewald et al. [Phys. Rev. Lett. 111, 235001 (2013)]. The same methodology applied to recently improved implosions using

Early-time radiation flux symmetry optimization and its effect on gas-filled hohlraum ignition targets on the National Ignition Facility

Science.gov (United States)

Milovich, J. L.; Dewald, E. L.; Pak, A.; Michel, P.; Town, R. P. J.; Bradley, D. K.; Landen, O.; Edwards, M. J.

2016-03-01

Achieving ignition on the National Ignition Facility (NIF) is tied to our ability to control and minimize deviations from sphericity of the capsule implosion. Low-mode asymmetries of the hot spot result from the combined effect of radiation drive asymmetries throughout the laser pulse and initial roughness on the capsule surface. In this paper, we report on simulations and experiments designed to assess, measure, and correct the drive asymmetries produced by the early-time (≈first 2 ns or "picket") period of the laser pulse. The drive asymmetry during the picket is commonly thought to introduce distortions in the hot-spot shape at ignition time. However, a more subtle effect not previously considered is that it also leads to an asymmetry in shock velocity and timing, thereby increasing the fuel adiabat and reducing the margin for ignition. It is shown via hydrodynamic simulations that minimizing this effect requires that the early-time asymmetry be kept below 7.5% in the second Legendre mode (P2), thus keeping the loss of performance margin below ≈10% for a layered implosion. Asymmetries during the picket of the laser pulse are measured using the instantaneous self-emission of a high-Z re-emission sphere in place of an ignition capsule in a hohlraum with large azimuthal diagnostic windows. Three dimensional simulations using the code HYDRA (to capture the effect of non-azimuthal hohlraum features) coupled to a cross-beam energy transfer model [Michel et al., Phys. Plasmas 17, 056305 (2010)] are used to establish the surrogacy of the re-emit target and to assess the early-time drive symmetry. Calculations using this model exhibit the same sensitivity to variations in the relative input powers between the different cones of NIF beams as measured for the "Rev5" CH target [Haan et al., Phys Plasmas 18, 051001 (2011)] and reported by Dewald et al. [Phys. Rev. Lett. 111, 235001 (2013)]. The same methodology applied to recently improved implosions using different

Tungsten Z-Pinch Long Implosions on the Saturn Generator

International Nuclear Information System (INIS)

DOUGLAS, MELISSA R.; DEENEY, Christopher; SPIELMAN, RICK B.; COVERDALE, CHRISTINE A.; RODERICK, N.F.; HAINES, M.G.

1999-01-01

Recent success on the Saturn and Z accelerators at Sandia National Laboratories have demonstrated the ability to scale z-pinch parameters to increasingly larger current pulsed power facilities. Next generation machines will require even larger currents (>20 MA), placing further demands on pulsed power technology. To this end, experiments have been carried out on Saturn operating in a long pulse mode, investigating the potential of lower voltages and longer implosion times while still maintaining pinch fidelity. High wire number, 25 mm diameter tungsten arrays were imploded with implosion times ranging from 130 to 240 ns. The results were comparable to those observed in the Saturn short pulse mode, with risetimes on the order of 4.5 to 6.5 ns. Experimental data will be presented, along with two dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment

Alternative hot spot formation techniques using liquid deuterium-tritium layer inertial confinement fusion capsules

International Nuclear Information System (INIS)

Olson, R. E.; Leeper, R. J.

2013-01-01

The baseline DT ice layer inertial confinement fusion (ICF) ignition capsule design requires a hot spot convergence ratio of ∼34 with a hot spot that is formed from DT mass originally residing in a very thin layer at the inner DT ice surface. In the present paper, we propose alternative ICF capsule designs in which the hot spot is formed mostly or entirely from mass originating within a spherical volume of DT vapor. Simulations of the implosion and hot spot formation in two DT liquid layer ICF capsule concepts—the DT wetted hydrocarbon (CH) foam concept and the “fast formed liquid” (FFL) concept—are described and compared to simulations of standard DT ice layer capsules. 1D simulations are used to compare the drive requirements, the optimal shock timing, the radial dependence of hot spot specific energy gain, and the hot spot convergence ratio in low vapor pressure (DT ice) and high vapor pressure (DT liquid) capsules. 2D simulations are used to compare the relative sensitivities to low-mode x-ray flux asymmetries in the DT ice and DT liquid capsules. It is found that the overall thermonuclear yields predicted for DT liquid layer capsules are less than yields predicted for DT ice layer capsules in simulations using comparable capsule size and absorbed energy. However, the wetted foam and FFL designs allow for flexibility in hot spot convergence ratio through the adjustment of the initial cryogenic capsule temperature and, hence, DT vapor density, with a potentially improved robustness to low-mode x-ray flux asymmetry

The near vacuum hohlraum campaign at the NIF: A new approach

Science.gov (United States)

Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N.; Turnbull, D.; Mackinnon, A. J.; Ho, D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E.; Benedetti, L. R.; Nagel, S.; Biener, J.; Callahan, D. A.; Yeamans, C.; Michel, P.; Schneider, M.; Kozioziemski, B.; Ma, T.; Macphee, A. G.; Haan, S.; Izumi, N.; Hatarik, R.; Sterne, P.; Celliers, P.; Ralph, J.; Rygg, R.; Strozzi, D.; Kilkenny, J.; Rosenberg, M.; Rinderknecht, H.; Sio, H.; Gatu-Johnson, M.; Frenje, J.; Petrasso, R.; Zylstra, A.; Town, R.; Hurricane, O.; Nikroo, A.; Edwards, M. J.

2016-05-01

The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30×). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examine the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30× implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.

The near vacuum hohlraum campaign at the NIF: A new approach

Energy Technology Data Exchange (ETDEWEB)

Le Pape, S.; Berzak Hopkins, L. F.; Divol, L.; Meezan, N.; Turnbull, D.; Ho, D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E.; Benedetti, L. R.; Nagel, S.; Biener, J.; Callahan, D. A.; Yeamans, C.; Michel, P.; Schneider, M.; Kozioziemski, B.; Ma, T.; Macphee, A. G. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2016-05-15

The near vacuum campaign on the National Ignition Facility has concentrated its efforts over the last year on finding the optimum target geometry to drive a symmetric implosion at high convergence ratio (30×). As the hohlraum walls are not tamped with gas, the hohlraum is filling with gold plasma and the challenge resides in depositing enough energy in the hohlraum before it fills up. Hohlraum filling is believed to cause symmetry swings late in the pulse that are detrimental to the symmetry of the hot spot at high convergence. This paper describes a series of experiments carried out to examine the effect of increasing the distance between the hohlraum wall and the capsule (case to capsule ratio) on the symmetry of the hot spot. These experiments have shown that smaller Case to Capsule Ratio (CCR of 2.87 and 3.1) resulted in oblate implosions that could not be tuned round. Larger CCR (3.4) led to a prolate implosion at convergence 30× implying that inner beam propagation at large CCR is not impeded by the expanding hohlraum plasma. A Case to Capsule ratio of 3.4 is a promising geometry to design a round implosion but in a smaller hohlraum where the hohlraum losses are lower, enabling a wider cone fraction range to adjust symmetry.

Results from annual testing of ARECO cesium capsules from 1990-1994

Energy Technology Data Exchange (ETDEWEB)

Lundeen, J.E.

1994-10-01

The purpose of this report is to compile the results of the cesium capsule inspections and testing at the Applied Radiant Energy Corporation (ARECO) facility in Lynchburg, VA, performed in 1990, 1991, 1992, 1993, and 1994. The 25 cesium capsules at the ARECO facility were visually identified and clunk tested. A Go/No Go gauge test was required for capsules failing the clunk test. A visual inspection of capsules was required for the initial testing (1990). All 25 capsules passed the inspections and testing each year.

Theoretical and simulation research of hydrodynamic instabilities in inertial-confinement fusion implosions

Science.gov (United States)

Wang, LiFeng; Ye, WenHua; He, XianTu; Wu, JunFeng; Fan, ZhengFeng; Xue, Chuang; Guo, HongYu; Miao, WenYong; Yuan, YongTeng; Dong, JiaQin; Jia, Guo; Zhang, Jing; Li, YingJun; Liu, Jie; Wang, Min; Ding, YongKun; Zhang, WeiYan

2017-05-01

Inertial fusion energy (IFE) has been considered a promising, nearly inexhaustible source of sustainable carbon-free power for the world's energy future. It has long been recognized that the control of hydrodynamic instabilities is of critical importance for ignition and high-gain in the inertial-confinement fusion (ICF) hot-spot ignition scheme. In this mini-review, we summarize the progress of theoretical and simulation research of hydrodynamic instabilities in the ICF central hot-spot implosion in our group over the past decade. In order to obtain sufficient understanding of the growth of hydrodynamic instabilities in ICF, we first decompose the problem into different stages according to the implosion physics processes. The decomposed essential physics pro- cesses that are associated with ICF implosions, such as Rayleigh-Taylor instability (RTI), Richtmyer-Meshkov instability (RMI), Kelvin-Helmholtz instability (KHI), convergent geometry effects, as well as perturbation feed-through are reviewed. Analyti- cal models in planar, cylindrical, and spherical geometries have been established to study different physical aspects, including density-gradient, interface-coupling, geometry, and convergent effects. The influence of ablation in the presence of preheating on the RTI has been extensively studied by numerical simulations. The KHI considering the ablation effect has been discussed in detail for the first time. A series of single-mode ablative RTI experiments has been performed on the Shenguang-II laser facility. The theoretical and simulation research provides us the physical insights of linear and weakly nonlinear growths, and nonlinear evolutions of the hydrodynamic instabilities in ICF implosions, which has directly supported the research of ICF ignition target design. The ICF hot-spot ignition implosion design that uses several controlling features, based on our current understanding of hydrodynamic instabilities, to address shell implosion stability, has

A scheme for reducing deceleration-phase Rayleigh-Taylor growth in inertial confinement fusion implosions

Science.gov (United States)

Wang, L. F.; Ye, W. H.; Wu, J. F.; Liu, Jie; Zhang, W. Y.; He, X. T.

2016-05-01

It is demonstrated that the growth of acceleration-phase instabilities in inertial confinement fusion implosions can be controlled, especially in the high-foot implosions [O. A. Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility. However, the excessive growth of the deceleration-phase instabilities can still destroy the hot spot ignition. A scheme is proposed to retard the deceleration-phase Rayleigh-Taylor instability growth by shock collision near the waist of the inner shell surface. Two-dimensional radiation hydrodynamic simulations confirm the improved deceleration-phase hot spot stability properties without sacrificing the fuel compression.

A scheme for reducing deceleration-phase Rayleigh–Taylor growth in inertial confinement fusion implosions

Energy Technology Data Exchange (ETDEWEB)

Wang, L. F., E-mail: wang-lifeng@iapcm.ac.cn; Ye, W. H.; Liu, Jie [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Center for Fusion Energy Science and Technology, Chinese Academy of Engineering Physics, Beijing 100088 (China); Wu, J. F. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Center for Fusion Energy Science and Technology, Chinese Academy of Engineering Physics, Beijing 100088 (China); Zhang, W. Y. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); He, X. T. [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871 (China)

2016-05-15

It is demonstrated that the growth of acceleration-phase instabilities in inertial confinement fusion implosions can be controlled, especially in the high-foot implosions [O. A. Hurricane et al., Phys. Plasmas 21, 056314 (2014)] on the National Ignition Facility. However, the excessive growth of the deceleration-phase instabilities can still destroy the hot spot ignition. A scheme is proposed to retard the deceleration-phase Rayleigh–Taylor instability growth by shock collision near the waist of the inner shell surface. Two-dimensional radiation hydrodynamic simulations confirm the improved deceleration-phase hot spot stability properties without sacrificing the fuel compression.

High-foot Implosion Workshop (March 22-24, 2016) Report

Energy Technology Data Exchange (ETDEWEB)

Hurricane, O. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-05-06

From March 22-24, 2016 at Workshop was held at Lawrence Livermore National Laboratory bringing together international experts in inertial confinement fusion research for the purpose of discussing the results from the ‘high-foot implosion campaign.’ The Workshop topics covered a retrospective of the first two years of experiments, a discussion of our best present understanding of what the data and our models imply, a discussion about remaining mysteries that are not understood at this time, and a discussion of our strategy moving forward. The material herein contains information from published and unpublished sources and is distributed solely for the purposes of this Workshop. Key assessments and conclusions resulting from the Workshop are: “The high foot campaign is extremely well documented and the interested reader is urged to go directly to the peer-reviewed journal literature for details.” – D. Haynes (LANL) “Overall progress in understanding of fuel and hot-spot properties near peak burn is excellent.” – V. Goncharov (LLE) “I would say that given the constraints of using the same hohlraum and similar capsule designs to the National Ignition Campaign, the High Foot Campaign achieved as much as could be expected. Indeed the demonstration of significant alpha particle heating remains a landmark achievement.” – J. Chittenden (Imperial College) “One of the principal points of discussion at the meeting was the importance of the roll over in inferred pressure that occurs with reducing coast time for different ablator thicknesses and the idea of repeating shot N140819 to confirm this. I would be very interested to see a return to the High Foot platform as a way to exercise the improved radiographic capabilities such as the curved crystal imaging system and as a way to examine the hypothesis of ‘burn truncation by aneurism.’ ” – J. Chittenden (Imperial College) “It is clear from the quality of the data presented during this workshop

QUICK-FIRE: Plasma flow driven implosion experiments

International Nuclear Information System (INIS)

Baker, W.L.; Bigelow, W.S.; Degnan, J.H.

1985-01-01

High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion

A diamond detector for inertial confinement fusion X-ray bang-time measurements at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

MacPhee, A G; Brown, C; Burns, S; Celeste, J; Glenzer, S H; Hey, D; Jones, O S; Landen, O; Mackinnon, A J; Meezan, N; Parker, J; Edgell, D; Glebov, V Y; Kilkenny, J; Kimbrough, J

2010-11-09

An instrument has been developed to measure X-ray bang-time for inertial confinement fusion capsules; the time interval between the start of the laser pulse and peak X-ray emission from the fuel core. The instrument comprises chemical vapor deposited polycrystalline diamond photoconductive X-ray detectors with highly ordered pyrolytic graphite X-ray monochromator crystals at the input. Capsule bang-time can be measured in the presence of relatively high thermal and hard X-ray background components due to the selective band pass of the crystals combined with direct and indirect X-ray shielding of the detector elements. A five channel system is being commissioned at the National Ignition Facility at Lawrence Livermore National Laboratory for implosion optimization measurements as part of the National Ignition Campaign. Characteristics of the instrument have been measured demonstrating that X-ray bang-time can be measured with {+-} 30ps precision, characterizing the soft X-ray drive to +/- 1eV or 1.5%.

Spectroscopic diagnostics of NIF ICF implosions using line ratios of Kr dopant in the ignition capsule

Science.gov (United States)

Dasgupta, Arati; Ouart, Nicholas; Giuiani, John; Clark, Robert; Schneider, Marilyn; Scott, Howard; Chen, Hui; Ma, Tammy

2017-10-01

X ray spectroscopy is used on the NIF to diagnose the plasma conditions in the ignition target in indirect drive ICF implosions. A platform is being developed at NIF where small traces of krypton are used as a dopant to the fuel gas for spectroscopic diagnostics using krypton line emissions. The fraction of krypton dopant was varied in the experiments and was selected so as not to perturb the implosion. Our goal is to use X-ray spectroscopy of dopant line ratios produced by the hot core that can provide a precise measurement of electron temperature. Simulations of the krypton spectra using a 1 in 104 atomic fraction of krypton in direct-drive exploding pusher with a range of electron temperatures and densities show discrepancies when different atomic models are used. We use our non-LTE atomic model with a detailed fine-structure level atomic structure and collisional-radiative rates to investigate the krypton spectra at the same conditions. Synthetic spectra are generated with a detailed multi-frequency radiation transport scheme from the emission regions of interest to analyze the experimental data with 0.02% Kr concentration and compare and contrast with the existing simulations at LLNL. Work supported by DOE/NNSA; Part of this work was also done under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Using multiple secondary fusion products to evaluate fuel ρR, electron temperature, and mix in deuterium-filled implosions at the NIF

Energy Technology Data Exchange (ETDEWEB)

Rinderknecht, H. G., E-mail: hgr@mit.edu; Rosenberg, M. J.; Zylstra, A. B.; Lahmann, B.; Séguin, F. H.; Frenje, J. A.; Li, C. K.; Gatu Johnson, M.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Berzak Hopkins, L. F.; Caggiano, J. A.; Divol, L.; Hartouni, E. P.; Hatarik, R.; Hatchett, S. P.; Le Pape, S.; Mackinnon, A. J.; McNaney, J. M.; Meezan, N. B.; Moran, M. J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); and others

2015-08-15

In deuterium-filled inertial confinement fusion implosions, the secondary fusion processes D({sup 3}He,p){sup 4}He and D(T,n){sup 4}He occur, as the primary fusion products {sup 3}He and T react in flight with thermal deuterons. In implosions with moderate fuel areal density (∼5–100 mg/cm{sup 2}), the secondary D-{sup 3}He reaction saturates, while the D-T reaction does not, and the combined information from these secondary products is used to constrain both the areal density and either the plasma electron temperature or changes in the composition due to mix of shell material into the fuel. The underlying theory of this technique is developed and applied to three classes of implosions on the National Ignition Facility: direct-drive exploding pushers, indirect-drive 1-shock and 2-shock implosions, and polar direct-drive implosions. In the 1- and 2-shock implosions, the electron temperature is inferred to be 0.65 times and 0.33 times the burn-averaged ion temperature, respectively. The inferred mixed mass in the polar direct-drive implosions is in agreement with measurements using alternative techniques.

Simulation experiment of laser implosion

International Nuclear Information System (INIS)

Sakagami, Yukio; Kano, Takahide

1980-01-01

This paper is concerned with experimental studies on instabilities associated with implosion shock waves. Double cylindrical implosion shock tube is used. Instabilities of mode number l asymptotically equals 12 are observed in spite of initial perturbation of l asymptotically equals 100. This phenomenon is explained by Rayleigh-Taylor Instability. (author)

Results from MARBLE DT Experiments on the National Ignition Facility: Implosion of Foam-Filled Capsules for Studying Thermonuclear Burn in the Presence of Heterogeneous Mix

Science.gov (United States)

Murphy, T. J.; Douglas, M. R.; Cardenas, T.; Cooley, J. H.; Gunderson, M. A.; Haines, B. M.; Hamilton, C. E.; Kim, Y.; Lee, M. N.; Oertel, J. A.; Olson, R. E.; Randolph, R. B.; Shah, R. C.; Smidt, J. M.

2017-10-01

The MARBLE campaign on NIF investigates the effect of heterogeneous mix on thermonuclear burn for comparison to a probability distribution function (PDF) burn model. MARBLE utilizes plastic capsules filled with deuterated plastic foam and tritium gas. The ratio of DT to DD neutron yield is indicative of the degree to which the foam and the gas atomically mix. Platform development experiments have been performed to understand the behavior of the foam and of the gas separately using two types of capsule. The first experiments using deuterated foam and tritium gas have been performed. Results of these experiments, and the implications for our understanding of thermonuclear burn in heterogeneously mixed separated reactant experiments will be discussed. This work is supported by US DOE/NNSA, performed at LANL, operated by LANS LLC under contract DE-AC52-06NA25396.

Isochoric Implosions for Fast Ignition

International Nuclear Information System (INIS)

Clark, D S; Tabak, M

2007-01-01

Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hot spot ignition counterpart [e.g., S. Atzeni, Phys. Plasmas 6, 3316 (1999); M. Tabak et al., Fusion Sci. and Technology 49, 254 (2006)]. These gain models, however, all assume nearly uniform-density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley [Luftfahrtforschung 19, 302 (1942)] may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g=cm 3 and areal density of 2.4 g=cm 2 using 485 kJ of laser energy

Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

Science.gov (United States)

Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J. P.; Chittenden, J. P.; Lebedev, S. V.; Jennings, C. A.; Bland, S. N.

2006-01-01

Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1μs rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-θ simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions.

Wire Array Z-pinches on Sphinx Machine: Experimental Results and Relevant Points of Microsecond Implosion Physics

International Nuclear Information System (INIS)

Calamy, H.; Hamann, F.; Lassalle, F.; Bayol, F.; Mangeant, C.; Morell, A.; Huet, D.; Bedoch, J.P.; Chittenden, J.P.; Lebedev, S.V.; Jennings, C.A.; Bland, S.N.

2006-01-01

Centre d'Etudes de Gramat (France) has developed an efficient long implosion time (800 ns) Aluminum plasma radiation source (PRS). Based on the LTD technology, the SPHINX facility is developed as a 1-3MJ, 1μs rise time, 4-10 MA current driver. In this paper, it was used in 1MJ, 4MA configuration to drive Aluminum nested wire arrays Z-pinches with K-shell yield up to 20 kJ and a FWHM of the x-ray pulse of about 50 ns. We present latest SPHINX experiments and some of the main physic issues of the microsecond regime. Experimental setup and results are described with the aim of giving trends that have been obtained. The main features of microsecond implosion of wire arrays can be analyzed thanks to same methods and theories as used for faster Z-pinches. The effect of load polarity was examined. The stability of the implosion , one of the critical point of microsecond wire arrays due to the load dimensions imposed by the time scale, is tackled. A simple scaling from 100 ns Z-pinch results to 800 ns ones gives good results and the use of nested arrays improves dramatically the implosion quality and the Kshell yield of the load. However, additional effects such as the impact of the return current can geometry on the implosion have to be taken into account on our loads. Axial inhomogeneity of the implosion the origin of which is not yet well understood occurs in some shots and impacts the radiation output. The shape of the radiative pulse is discussed and compared with the homogeneity of the implosion. Numerical 2D R-Z and R-θ simulations are used to highlight some experimental results and understand the plasma conditions during these microsecond wire arrays implosions

The NIF: An international high energy density science and inertial fusion user facility

Directory of Open Access Journals (Sweden)

Moses E.I.

2013-11-01

Full Text Available The National Ignition Facility (NIF, a 1.8-MJ/500-TW Nd:Glass laser facility designed to study inertial confinement fusion (ICF and high-energy-density science (HEDS, is operational at Lawrence Livermore National Laboratory (LLNL. A primary goal of NIF is to create the conditions necessary to demonstrate laboratory-scale thermonuclear ignition and burn. NIF experiments in support of indirect-drive ignition began late in FY2009 as part of the National Ignition Campaign (NIC, an international effort to achieve fusion ignition in the laboratory. To date, all of the capabilities to conduct implosion experiments are in place with the goal of demonstrating ignition and developing a predictable fusion experimental platform in 2012. The results from experiments completed are encouraging for the near-term achievement of ignition. Capsule implosion experiments at energies up to 1.6 MJ have demonstrated laser energetics, radiation temperatures, and symmetry control that scale to ignition conditions. Of particular importance is the demonstration of peak hohlraum temperatures near 300 eV with overall backscatter less than 15%. Important national security and basic science experiments have also been conducted on NIF. Successful demonstration of ignition and net energy gain on NIF will be a major step towards demonstrating the feasibility of laser-driven Inertial Fusion Energy (IFE. This paper will describe the results achieved so far on the path toward ignition, the beginning of fundamental science experiments and the plans to transition NIF to an international user facility providing access to HEDS and fusion energy researchers around the world.

The NIF: An international high energy density science and inertial fusion user facility

Science.gov (United States)

Moses, E. I.; Storm, E.

2013-11-01

The National Ignition Facility (NIF), a 1.8-MJ/500-TW Nd:Glass laser facility designed to study inertial confinement fusion (ICF) and high-energy-density science (HEDS), is operational at Lawrence Livermore National Laboratory (LLNL). A primary goal of NIF is to create the conditions necessary to demonstrate laboratory-scale thermonuclear ignition and burn. NIF experiments in support of indirect-drive ignition began late in FY2009 as part of the National Ignition Campaign (NIC), an international effort to achieve fusion ignition in the laboratory. To date, all of the capabilities to conduct implosion experiments are in place with the goal of demonstrating ignition and developing a predictable fusion experimental platform in 2012. The results from experiments completed are encouraging for the near-term achievement of ignition. Capsule implosion experiments at energies up to 1.6 MJ have demonstrated laser energetics, radiation temperatures, and symmetry control that scale to ignition conditions. Of particular importance is the demonstration of peak hohlraum temperatures near 300 eV with overall backscatter less than 15%. Important national security and basic science experiments have also been conducted on NIF. Successful demonstration of ignition and net energy gain on NIF will be a major step towards demonstrating the feasibility of laser-driven Inertial Fusion Energy (IFE). This paper will describe the results achieved so far on the path toward ignition, the beginning of fundamental science experiments and the plans to transition NIF to an international user facility providing access to HEDS and fusion energy researchers around the world.

Processes to Open the Container and the Sample Catcher of the Hayabusa Returned Capsule in the Planetary Material Sample Curation Facility of JAXA

Science.gov (United States)

Fujimura, A.; Abe, M.; Yada, T.; Nakamura, T.; Noguchi, T.; Okazaki, R.; Ishibashi, Y.; Shirai, K.; Okada, T.; Yano, H.;

Spatially resolved x-ray fluorescence spectroscopy of beryllium capsule implosions at the NIF

Science.gov (United States)

MacDonald, M. J.; Bishel, D. T.; Saunders, A. M.; Scott, H. A.; Kyrala, G.; Kline, J.; MacLaren, S.; Thorn, D. B.; Yi, S. A.; Zylstra, A. B.; Falcone, R. W.; Doeppner, T.

2017-10-01

Beryllium ablators used in indirectly driven inertial confinement fusion implosions are doped with copper to prevent preheat of the cryogenic hydrogen fuel. Here, we present analysis of spatially resolved copper K- α fluorescence spectra from the beryllium ablator layer. It has been shown that K- α fluorescence spectroscopy can be used to measure plasma conditions of partially ionized dopants in high energy density systems. In these experiments, K-shell vacancies in the copper dopant are created by the hotspot emission at stagnation, resulting in K-shell fluorescence at bang time. Spatially resolved copper K- α emission spectra are compared to atomic kinetics and radiation code simulations to infer density and temperature profiles. This work was supported by the US DOE under Grant No. DE-NA0001859, under the auspices of the US DOE by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344, and by Los Alamos National Laboratory under contract DE-AC52-06NA52396.

Reconstruction and analysis of temperature and density spatial profiles inertial confinement fusion implosion cores

International Nuclear Information System (INIS)

Mancini, R. C.

2007-01-01

We discuss several methods for the extraction of temperature and density spatial profiles in inertial confinement fusion implosion cores based on the analysis of the x-ray emission from spectroscopic tracers added to the deuterium fuel. The ideas rely on (1) detailed spectral models that take into account collisional-radiative atomic kinetics, Stark broadened line shapes, and radiation transport calculations, (2) the availability of narrow-band, gated pinhole and slit x-ray images, and space-resolved line spectra of the core, and (3) several data analysis and reconstruction methods that include a multi-objective search and optimization technique based on a novel application of Pareto genetic algorithms to plasma spectroscopy. The spectroscopic analysis yields the spatial profiles of temperature and density in the core at the collapse of the implosion, and also the extent of shell material mixing into the core. Results are illustrated with data recorded in implosion experiments driven by the OMEGA and Z facilities

Summary Report for Capsule Dry Storage Project

Energy Technology Data Exchange (ETDEWEB)

JOSEPHSON, W S

2003-09-04

There are 1.936 cesium (Cs) and strontium (Sr) capsules stored in pools at the Waste Encapsulation and Storage Facility (WESF). These capsules will be moved to dry storage on the Hanford Site as an interim measure to reduce risk. The Cs/Sr Capsule Dry Storage Project (CDSP) is conducted under the assumption the capsules will eventually be moved to the repository at Yucca Mountain, and the design criteria include requirements that will facilitate acceptance at the repository. The storage system must also permit retrieval of capsules in the event vitrification of the capsule contents is pursued. A cut away drawing of a typical cesium chloride (CsCI) capsule and the capsule property and geometry information are provided in Figure 1.1. Strontium fluoride (SrF{sub 2}) capsules are similar in design to CsCl capsules. Further details of capsule design, current state, and reference information are given later in this report and its references. Capsule production and life history is covered in WMP-16938, Capsule Characterization Report for Capsule Dry Storage Project, and is briefly summarized in Section 5.2 of this report.

Quick-fire: Plasma flow driven implosion experiments

International Nuclear Information System (INIS)

Baker, W.L.; Bigelow, W.S.; Degnan, J.H.

1985-01-01

High speed plasma implosions involving megajoules of energy, and sub-microsecond implosion times are expected to require additional stages of power conditioning between realistic primary energy sources and the implosion system. Plasma flow switches and vacuum inductive stores represent attractive alternates to the high speed fuse and atmospheric store techniques which have been previously reported for powering such plasma experiments. In experiments being conducted at the Air Force Weapons Lab, a washer shaped plasma accelerated to 7-10 cm/microsecond in a coaxial plasma gun configuration, represents the moving element in a vacuum store/power conditioning system of 16.5 nH inductance which stores 1-1.5 MJ at 12-14 MA. At the end of the coaxial gun, the moving element transits the 2cm axial length of the cylindrical implosion gap in 200-400 nS, delivering the magnetic energy to the implosion foil, accelerating the imploding plasma to speeds of 30-40 cm/microsecond in 350-450 nS, and delivering a projected 400 KJ of kinetic energy to the implosion. Experiments have been conducted using the SHIVA STAR capacitor bank operating at 6 MJ stored energy in which performance has been monitored by electrical diagnostics, magnetic probes, and axial and radial viewing high speed visible and X-Ray photographs to assess the performance of the coaxial run and coaxial to radial transition. Time and spectrally resolved X-Ray diagnostics are used to assess implosion quality and performance and results are compared to kinematic and MHD models

Neutron temporal diagnostic for high-yield deuterium–tritium cryogenic implosions on OMEGA

Energy Technology Data Exchange (ETDEWEB)

Stoeckl, C.; Boni, R.; Ehrne, F.; Forrest, C. J.; Glebov, V. Yu.; Katz, J.; Lonobile, D. J.; Magoon, J.; Regan, S. P.; Shoup, M. J.; Sorce, A.; Sorce, C.; Sangster, T. C.; Weiner, D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

2016-05-15

A next-generation neutron temporal diagnostic (NTD) capable of recording high-quality data for the highest anticipated yield cryogenic deuterium–tritium (DT) implosion experiments was recently installed at the Omega Laser Facility. A high-quality measurement of the neutron production width is required to determine the hot-spot pressure achieved in inertial confinement fusion experiments—a key metric in assessing the quality of these implosions. The design of this NTD is based on a fast-rise-time plastic scintillator, which converts the neutron kinetic energy to 350- to 450-nm-wavelength light. The light from the scintillator inside the nose-cone assembly is relayed ∼16 m to a streak camera in a well-shielded location. An ∼200× reduction in neutron background was observed during the first high-yield DT cryogenic implosions compared to the current NTD installation on OMEGA. An impulse response of ∼40 ± 10 ps was measured in a dedicated experiment using hard x-rays from a planar target irradiated with a 10-ps short pulse from the OMEGA EP laser. The measured instrument response includes contributions from the scintillator rise time, optical relay, and streak camera.

Depth and Extent of Gas-Ablator Mix in Symcap Implosions at the National Ignition Facility

Science.gov (United States)

Pino, Jesse; Ma, T.; MacLaren, S. A.; Salmonson, J. D.; Ho, D.; Khan, S. F.; Masse, L.; Ralph, J. E.; Czajka, C.; Casey, D.; Sacks, R.; Smalyuk, V. A.; Tipton, R. E.; Kyrala, G. A.

2017-10-01

A longstanding question in ICF physics has been the extent to which capsule ablator material mixes into the burning fusion fuel and degrades performance. Several recent campaigns at the National Ignition Facility have examined this question through the use of separated reactants. A layer of CD plastic is placed on the inner surface of the CH shell and the shell is filled with a gas mixture of H and T. This allows for simultaneous neutron signals that inform different aspects of the physics; we get core TT neutron yield, atomic mix from the DT neutrons, and information about shell heating from the DD neutron signal. By systematically recessing the CD layer away from the gas boundary we gain an inference of the depth of the mixing layer. This presentation will cover three campaigns to look at mixing depth: An ignition-like design (``Low-foot'') at two convergence ratios, as well as a robust, nearly one-dimensional, low convergence, symmetric platform designed to minimize ablation front feed-through (HED 2-shock). We show that the 2-shock capsule has less ablator-gas mix, and compare the experimental results to mix-model simulations. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344, LLNS, LLC.

Criteria for cesium capsules to be shipped as special form radioactive material

International Nuclear Information System (INIS)

Lundeen, J.E.

1994-01-01

The purpose of this report is to compile all the documentation which defines the criteria for Waste Encapsulation and Storage Facility (WESF) cesium capsules at the IOTECH facility and Applied Radiant Energy Corporation (ARECO) to be shipped as special form radioactive material in the Beneficial Uses Shipping System (BUSS) Cask. The capsules were originally approved as special form in 1975, but in 1988 the integrity of the capsules came into question. WHC developed the Pre-shipment Acceptance Test Criteria for capsules to meet in order to be shipped as special form material. The Department of Energy approved the criteria and directed WHC to ship the capsules at IOTECH and ARECO meeting this criteria to WHC as special form material

Mix and instability growth seeded at the inner surface of CH-ablator implosions on the National Ignition Facility

Science.gov (United States)

Haan, S. W.; Celliers, P. M.; Collins, G. W.; Orth, C. D.; Clark, D. S.; Amendt, P.; Hammel, B. A.; Robey, H. F.; Huang, H.

2014-10-01

Mix and hydro instability growth are key issues in implosions of ignition targets on NIF. The implosions are designed so that the amplitude of perturbations is thought to be determined by initial seeds to the hydrodynamic instabilities, amplified by an instability growth factor. Experiments have indicated that growth factors can be calculated fairly well, but characterizing the initial seeds is an ongoing effort. Several threads of investigation this year have increased our understanding of growth seeded at the CH/DT interface. These include: more detailed characterization of the CH inner surface; possible other seeds, such as density irregularities either from fabrication defects or arising during the implosion; experiments on the Omega laser measuring velocity modulations on shock fronts shortly after breaking out from the CH, which can seed subsequent growth; and the possible significance of non-hydrodynamic effects such as plasma interpenetration or spall-like ejecta upon shock breakout. This presentation describes these developments, the relationships between them, and their implications for ignition target performance. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Trade study for the disposition of cesium and strontium capsules

International Nuclear Information System (INIS)

Claghorn, R.D.

1996-03-01

This trade study analyzes alternatives for the eventual disposal of cesium and strontium capsules currently stored at the Waste Encapsulation and Storage Facility as by-product. However, for purposes of this study, it is assumed that at some time in the future, the capsules will be declared high-level waste and therefore will require disposal at an offsite geologic repository. The study considered numerous alternatives and selected three for detailed analysis: (1) overpack and storage at high-level waste canister storage building, (2) overpack at the high-level waste vitrification facility followed by storage at a high-level waste canister storage building, and (3) blend capsule contents with other high-level waste feed streams and vitrify at the high-level waste vitrification facility

Using absolute x-ray spectral measurements to infer stagnation conditions in ICF implosions

Science.gov (United States)

Patel, Pravesh; Benedetti, L. R.; Cerjan, C.; Clark, D. S.; Hurricane, O. A.; Izumi, N.; Jarrott, L. C.; Khan, S.; Kritcher, A. L.; Ma, T.; Macphee, A. G.; Landen, O.; Spears, B. K.; Springer, P. T.

2016-10-01

Measurements of the continuum x-ray spectrum emitted from the hot-spot of an ICF implosion can be used to infer a number thermodynamic properties at stagnation including temperature, pressure, and hot-spot mix. In deuterium-tritium (DT) layered implosion experiments on the National Ignition Facility (NIF) we field a number of x-ray diagnostics that provide spatial, temporal, and spectrally-resolved measurements of the radiated x-ray emission. We report on analysis of these measurements using a 1-D hot-spot model to infer thermodynamic properties at stagnation. We compare these to similar properties that can be derived from DT fusion neutron measurements. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Fusion Yield Enhancement in Magnetized Laser-Driven Implosions

International Nuclear Information System (INIS)

Chang, P. Y.; Fiksel, G.; Hohenberger, M.; Knauer, J. P.; Marshall, F. J.; Betti, R.; Meyerhofer, D. D.; Seguin, F. H.; Petrasso, R. D.

2011-01-01

Enhancement of the ion temperature and fusion yield has been observed in magnetized laser-driven inertial confinement fusion implosions on the OMEGA Laser Facility. A spherical CH target with a 10 atm D 2 gas fill was imploded in a polar-drive configuration. A magnetic field of 80 kG was embedded in the target and was subsequently trapped and compressed by the imploding conductive plasma. As a result of the hot-spot magnetization, the electron radial heat losses were suppressed and the observed ion temperature and neutron yield were enhanced by 15% and 30%, respectively.

Analysis of target implosion irradiated by proton beam, (1)

International Nuclear Information System (INIS)

Tamba, Moritake; Nagata, Norimasa; Kawata, Shigeo; Niu, Keishiro.

1982-10-01

Numerical simulation and analysis were performed for the implosion of a hollow shell target driven by proton beam. The target consists of three layers of Pb, Al and DT. As the Al layer is heated by proton beam, the layer expands and pushes the DT layer toward the target center. To obtain the optimal velocity of DT implosion, the optimal target size and optimal layer thickness were determined. The target size is determined by, for example, the instability of the implosion or beam focusing on the target surface. The Rayleigh-Taylor instability and the unstable implosion due to the inhomogeneity were investigated. Dissipation, nonlinear effects and density gradient at the boundary were expected to reduce the growth rate of the Rayleigh-Taylor instability during the implosion. In order that the deviation of the boundary surface during the implosion is less than the thickness of fuel, the inhomogeneity of the temperature and the density of the target should be less than ten percent. The amplitude of the boundary surface roughness is required to be less than 4 micrometer. (Kato, T.)

Demonstration of Ion Kinetic Effects in Inertial Confinement Fusion Implosions and Investigation of Magnetic Reconnection Using Laser-Produced Plasmas

Science.gov (United States)

Rosenberg, M. J.

2016-10-01

Shock-driven laser inertial confinement fusion (ICF) implosions have demonstrated the presence of ion kinetic effects in ICF implosions and also have been used as a proton source to probe the strongly driven reconnection of MG magnetic fields in laser-generated plasmas. Ion kinetic effects arise during the shock-convergence phase of ICF implosions when the mean free path for ion-ion collisions (λii) approaches the size of the hot-fuel region (Rfuel) and may impact hot-spot formation and the possibility of ignition. To isolate and study ion kinetic effects, the ratio of N - K =λii /Rfuel was varied in D3He-filled, shock-driven implosions at the Omega Laser Facility and the National Ignition Facility, from hydrodynamic-like conditions (NK 0.01) to strongly kinetic conditions (NK 10). A strong trend of decreasing fusion yields relative to the predictions of hydrodynamic models is observed as NK increases from 0.1 to 10. Hydrodynamics simulations that include basic models of the kinetic effects that are likely to be present in these experiments-namely, ion diffusion and Knudsen-layer reduction of the fusion reactivity-are better able to capture the experimental results. This type of implosion has also been used as a source of monoenergetic 15-MeV protons to image magnetic fields driven to reconnect in laser-produced plasmas at conditions similar to those encountered at the Earth's magnetopause. These experiments demonstrate that for both symmetric and asymmetric magnetic-reconnection configurations, when plasma flows are much stronger than the nominal Alfvén speed, the rate of magnetic-flux annihilation is determined by the flow velocity and is largely insensitive to initial plasma conditions. This work was supported by the Department of Energy Grant Number DENA0001857.

Implosion dynamics of a megampere wire-array Z-pinch with an inner low-density foam shell at the Angara-5-1 facility

International Nuclear Information System (INIS)

Aleksandrov, V. V.; Bolkhovitinov, E. A.; Volkov, G. S.; Grabovski, E. V.; Gritsuk, A. N.; Medovshchikov, S. F.; Oleinik, G. M.; Rupasov, A. A.; Frolov, I. N.

2016-01-01

The implosion dynamics of a pinch with a highly inhomogeneous initial axial distribution of the load mass was studied experimentally. A cascade array consisting of a double nested tungsten wire array and a coaxial inner cylindrical shell located symmetrically with respect to the high-voltage electrodes was used as a load of the Angara-5-1 high-current generator. The cylindrical foam shell was half as long as the cathode− anode gap, and its diameter was equal to the diameter of the inner wire array. It is shown experimentally that two stages are typical of the implosion dynamics of such a load: the formation of two separate pinches formed as a result of implosion of the wire array near the cathode and anode and the subsequent implosion of the central part of the load containing the cylindrical foam shell. The conditions are determined at which the implosion of the central part of the pinch with the foam cylinder is preceded by intense irradiation of the foam with the soft X-ray (SXR) emission generated by the near-electrode pinches and converting it into the plasma state. Using such a load, which models the main elements of the scheme of a dynamic hohlraum for inertial confinement fusion, it is possible to increase the efficiency of interaction between the outer accelerated plasma sheath and the inner foam shell by preionizing the foam with the SXR emission of the near-electrode pinches.

Three-dimensional hydrodynamic simulations of OMEGA implosions

Science.gov (United States)

Igumenshchev, I. V.; Michel, D. T.; Shah, R. C.; Campbell, E. M.; Epstein, R.; Forrest, C. J.; Glebov, V. Yu.; Goncharov, V. N.; Knauer, J. P.; Marshall, F. J.; McCrory, R. L.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.; Schmitt, A. J.; Obenschain, S.

2017-05-01

The effects of large-scale (with Legendre modes ≲ 10) asymmetries in OMEGA direct-drive implosions caused by laser illumination nonuniformities (beam-power imbalance and beam mispointing and mistiming), target offset, and variation in target-layer thickness were investigated using the low-noise, three-dimensional Eulerian hydrodynamic code ASTER. Simulations indicate that these asymmetries can significantly degrade the implosion performance. The most important sources of the asymmetries are the target offsets ( ˜10 to 20 μm), beam-power imbalance ( σrms˜10 %), and variations ( ˜5 %) in target-layer thickness. Large-scale asymmetries distort implosion cores, resulting in a reduced hot-spot confinement and an increased residual kinetic energy of implosion targets. The ion temperature inferred from the width of simulated neutron spectra is influenced by bulk fuel motion in the distorted hot spot and can result in up to an ˜1 -keV increase in apparent temperature. Similar temperature variations along different lines of sight are observed. Demonstrating hydrodynamic equivalence to ignition designs on OMEGA requires a reduction in large-scale target and laser-imposed nonuniformities, minimizing target offset, and employing highly efficient mid-adiabat (α = 4) implosion designs, which mitigate cross-beam energy transfer and suppress short-wavelength Rayleigh-Taylor growth.

Instability growth seeded by ablator material inhomogeneity in indirect drive implosions on the National Ignition Facility

Science.gov (United States)

Haan, Steven; Ali, S. J.; Baxamusa, S. H.; Celliers, P. M.; Clark, D. S.; Kritcher, A. L.; Nikroo, A.; Stadermann, M.; Biener, J.; Wallace, R.; Smalyuk, V.; Robey, H.; Weber, C. R.; Huang, H.; Reynolds, H.; Carlson, L.; Rice, N.; Kline, J. L.; Simakov, A. N.; Yi, S. A.

2017-10-01

NIF indirect drive ablators (CH, Be, and high density carbon HDC) show hydrodynamic irregularity beyond that expected from surface features. Characterizing these seeds and estimating their growth is important in projecting performance. The resulting modulations can be measured in x-ray backlit implosions on NIF called Hydro Growth Radiography, and on Omega with 2D velocimetry. This presentation summarizes the experiments for the three ablators, along with simulations thereof and projections of the significance for NIF. For CH, dominant seeds are photo-induced oxidation, which might be mitigated with alumina coating. For Be, perturbations result from Ar and O contamination. For HDC, perturbations are seeded by shock propagation around melt, depend on shock strength, and may constrain the adiabat of future HDC implosions. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Ultra High Mode Mix in NIF NIC Implosions

Science.gov (United States)

Scott, Robbie; Garbett, Warren

2017-10-01

This work re-examines a sub-set of the low adiabat implosions from the National Ignition Campaign in an effort to better understand potential phenomenological sources of `excess' mix observed experimentally. An extensive effort has been made to match both shock-timing and backlit radiography (Con-A) implosion data in an effort to reproduce the experimental conditions as accurately as possible. Notably a 30% reduction in ablation pressure at peak drive is required to match the experimental data. The reduced ablation pressure required to match the experimental data allows the ablator to decompress, in turn causing the DT ice-ablator interface to go Rayleigh-Taylor unstable early in the implosion acceleration phase. Post-processing the runs with various mix models indicates high-mode mix from the DT ice-ablator interface may penetrate deep into the hotspot. This work offers a potential explanation of why these low-adiabat implosions exhibited significantly higher levels of mix than expected from high-fidelity multi-dimensional simulations. Through this new understanding, a possible route forward for low-adiabat implosions on NIF is suggested.

Progress of LMJ-relevant implosions experiments on OMEGA

Directory of Open Access Journals (Sweden)

Casner A.

2013-11-01

Full Text Available In preparation of the first ignition attempts on the Laser Mégajoule (LMJ, an experimental program is being pursued on OMEGA to investigate LMJ-relevant hohlraums. First, radiation temperature levels close to 300 eV were recently achieved in reduced-scale hohlraums with modest backscatter losses. Regarding the baseline target design for fusion experiments on LMJ, an extensive experimental database has also been collected for scaled implosions experiments in both empty and gas-filled rugby-shaped hohlraums. We acquired a full picture of hohlraum energetics and implosion dynamics. Not only did the rugby hohlraums show significantly higher x-ray drive energy over the cylindrical hohlraums, but symmetry control by power balance was demonstrated, as well as high-performance D2 implosions enabling the use of a complete suite of neutrons diagnostics. Charged particle diagnostics provide complementary insights into the physics of these x-ray driven implosions. An overview of these results demonstrates our ability to control the key parameters driving the implosion, lending more confidence in extrapolations to ignition-scale targets.

Gamma Reaction History ablator areal density constraints upon correlated diagnostic modeling of National Ignition Facility implosion experiments

Energy Technology Data Exchange (ETDEWEB)

Cerjan, C., E-mail: cerjan1@llnl.gov; Sayre, D. B.; Landen, O. L.; Church, J. A.; Stoeffl, W. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Grafil, E. M. [Colorado School of Mines, Golden, Colorado 80401 (United States); Herrmann, H. W.; Hoffman, N. M.; Kim, Y. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2015-03-15

The inelastic neutron scattering induced γ-ray signal from {sup 12}C in an Inertial Confinement Fusion capsule is demonstrated to be an effective and general diagnostic for shell ablator areal density. Experimental acquisition of the time-integrated signal at 4.4 MeV using threshold detection from four gas Čerenkov cells provides a direct measurement of the {sup 12}C areal density near stagnation. Application of a three-dimensional isobaric static model of data acquired in a recent high neutron yield National Ignition Facility experimental campaign reveals two general trends: smaller remaining ablator mass at stagnation and higher shell density with increasing laser drive.

Precision Neutron Time-of-Flight Detectors Provide Insight into NIF Implosion Dynamics

Science.gov (United States)

Schlossberg, David; Eckart, M. J.; Grim, G. P.; Hartouni, E. P.; Hatarik, R.; Moore, A. S.; Waltz, C. S.

2017-10-01

During inertial confinement fusion, higher-order moments of neutron time-of-flight (nToF) spectra can provide essential information for optimizing implosions. The nToF diagnostic suite at the National Ignition Facility (NIF) was recently upgraded to include novel, quartz Cherenkov detectors. These detectors exploit the rapid Cherenkov radiation process, in contrast with conventional scintillator decay times, to provide high temporal-precision measurements that support higher-order moment analyses. Preliminary measurements have been made on the NIF during several implosions and initial results are presented here. Measured line-of-sight asymmetries, for example in ion temperatures, will be discussed. Finally, advanced detector optimization is shown to advance accessible physics, with possibilities for energy discrimination, gamma source identification, and further reduction in quartz response times. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

Advances in HYDRA and its applications to simulations of inertial confinement fusion targets

Directory of Open Access Journals (Sweden)

Marinak M.M.

2013-11-01

Full Text Available A new set of capabilities has been implemented in the HYDRA 2D/3D multiphysics inertial confinement fusion simulation code. These include a Monte Carlo particle transport library. It models transport of neutrons, gamma rays and light ions, as well as products they generate from nuclear and coulomb collisions. It allows accurate simulations of nuclear diagnostic signatures from capsule implosions. We apply it to here in a 3D simulation of a National Ignition Facility (NIF ignition capsule which models the full capsule solid angle. This simulation contains a severely rough ablator perturbation and provides diagnostics signatures of capsule failure due to excessive instability growth.

The Bigfoot Drive; Experimental Results

Science.gov (United States)

Baker, Kevin; Thomas, Cliff; Khan, Shahab; Casey, Daniel; Spears, Brian; Nora, Ryan; Munro, Davis; Eder, David; Milovich, Jose; Berger, Dick; Strozzi, David; Goyon, Clement; Turnbull, David; Ma, Tammy; Izumi, Nobuhiko; Benedetti, Robin; Millot, Marius; Celliers, Peter; Yeamans, Charles; Hatarik, Robert; Landen, Nino; Hurricane, Omar; Callahan, Debbie

2016-10-01

The Bigfoot platform was developed on the National Ignition Facility to investigate low convergence, high adiabat, high rhoR hotspot implosions. This platform was designed to be less susceptible to wall motion, LPI and CBET and to be more robust against capsule hydrodynamic instabilities. To date experimental studies have been carried out at two hohlraum scales, a 5.75 and 5.4 mm diameter hohlraum. We will present experimental results from these tuning campaigns including the shape vs. cone fraction, surrogacy comparisons of self-emission from the capsules vs. radiography of the imploding capsule and doped vs. undoped capsules. Prepared by LLNL under Contract DE-AC52-07NA27344.

Symmetry control in subscale near-vacuum hohlraums

Science.gov (United States)

Turnbull, D.; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Mackinnon, A.; Zylstra, A. B.; Rinderknecht, H. G.; Sio, H.; Petrasso, R. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J.

2016-05-01

Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. Specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

Symmetry control in subscale near-vacuum hohlraums

Energy Technology Data Exchange (ETDEWEB)

Turnbull, D., E-mail: turnbull2@llnl.gov; Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N.; Landen, O. L.; Ho, D. D.; Ross, J. S.; Khan, S.; Pak, A.; Dewald, E. L.; Callahan, D. A.; Hurricane, O.; Hsing, W. W.; Edwards, M. J. [National Ignition Facility, LLNL, Livermore, California 94550 (United States); Mackinnon, A. [National Ignition Facility, LLNL, Livermore, California 94550 (United States); Linac Coherent Light Source, SLAC, Menlo Park, California 94025 (United States); Zylstra, A. B. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Rinderknecht, H. G. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); National Ignition Facility, LLNL, Livermore, California 94550 (United States); Sio, H.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States)

2016-05-15

Controlling the symmetry of indirect-drive inertial confinement fusion implosions remains a key challenge. Increasing the ratio of the hohlraum diameter to the capsule diameter (case-to-capsule ratio, or CCR) facilitates symmetry tuning. By varying the balance of energy between the inner and outer cones as well as the incident laser pulse length, we demonstrate the ability to tune from oblate, through round, to prolate at a CCR of 3.2 in near-vacuum hohlraums at the National Ignition Facility, developing empirical playbooks along the way for cone fraction sensitivity of various laser pulse epochs. Radiation-hydrodynamic simulations with enhanced inner beam propagation reproduce most experimental observables, including hot spot shape, for a majority of implosions. Specular reflections are used to diagnose the limits of inner beam propagation as a function of pulse length.

Relationship between symmetry and laser pulse shape in low-fill hohlraums at the National Ignition Facility

Science.gov (United States)

MacLaren, Steve; Zylstra, A. B.; Yi, A.; Kline, J. L.; Kyrala, G. A.; Kot, L. B.; Loomis, E. N.; Perry, T. S.; Shah, R. C.; Masse, L. P.; Ralph, J. E.; Khan, S. F.

2017-10-01

Typically in indirect-drive inertial confinement fusion (ICF) hohlraums cryogenic helium gas fill is used to impede the motion of the hohlraum wall plasma as it is driven by the laser pulse. A fill of 1 mg/cc He has been used to significantly suppress wall motion in ICF hohlraums at the National Ignition Facility (NIF); however, this level of fill also causes laser-plasma instabilities (LPI) which result in hot electrons, time-dependent symmetry swings and reduction in drive due to increased backscatter. There are currently no adequate models for these phenomena in codes used to simulate integrated ICF experiments. A better compromise is a fill in the range of 0.3 0.6 mg/cc, which has been shown to provide some reduction in wall motion without incurring significant LPI effects. The wall motion in these low-fill hohlraums and the resulting effect on symmetry due to absorption of the inner cone beams by the outer cone plasma can be simulated with some degree of accuracy with the hydrodynamics and inverse Bremsstrahlung models in ICF codes. We describe a series of beryllium capsule implosions in 0.3 mg/cc He fill hohlraums that illustrate the effect of pulse shape on implosion symmetry in the ``low-fill'' regime. In particular, we find the shape of the beginning or ``foot'' of the pulse has significant leverage over the final symmetry of the stagnated implosion. This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344.

Progress in symmetric ICF capsule implosions and wire-array z-pinch source physics for double z-pinch driven hohlraums

International Nuclear Information System (INIS)

Bliss, David Emery; Vesey, Roger Alan; Rambo, Patrick K.; Lebedev, Sergey V.; Hanson, David L.; Nash, Thomas J.; Yu, Edmund P.; Matzen, Maurice Keith; Afeyan, Bedros B.; Smith, Ian Craig; Stygar, William A.; Porter, John Larry Jr.; Cuneo, Michael Edward; Bennett, Guy R.; Campbell, Robert B.; Sinars, Daniel Brian; Chittenden, Jeremy Paul; Waisman, Eduardo Mario; Mehlhorn, Thomas Alan

2005-01-01

Over the last several years, rapid progress has been made evaluating the double-z-pinch indirect-drive, inertial confinement fusion (ICF) high-yield target concept (Hammer et al 1999 Phys. Plasmas 6 2129). We have demonstrated efficient coupling of radiation from two wire-array-driven primary hohlraums to a secondary hohlraum that is large enough to drive a high yield ICF capsule. The secondary hohlraum is irradiated from two sides by z-pinches to produce low odd-mode radiation asymmetry. This double-pinch source is driven from a single electrical power feed (Cuneo et al 2002 Phys. Rev. Lett. 88 215004) on the 20 MA Z accelerator. The double z-pinch has imploded ICF capsules with even-mode radiation symmetry of 3.1 ± 1.4% and to high capsule radial convergence ratios of 14-21 (Bennett et al 2002 Phys. Rev. Lett. 89 245002; Bennett et al 2003 Phys. Plasmas 10 3717; Vesey et al 2003 Phys. Plasmas 10 1854). Advances in wire-array physics at 20 MA are improving our understanding of z-pinch power scaling with increasing drive current. Techniques for shaping the z-pinch radiation pulse necessary for low adiabat capsule compression have also been demonstrated.

Production of 131I gelatin capsules

International Nuclear Information System (INIS)

Freud, A.; Hirshfeld, N.; Canfi, A.; Melamud, Y.

1997-01-01

Radioiodine ( 131 I) hard-gelatin capsules are widely used for the diagnosis and treatment of various thyroid disorders. Until 1980 radioiodine was supplied by us as a liquid dosage. This proved to be a rather inconvenient form since it resulted in inaccurate dosing by the physicians and caused frequent contamination of the patients and the hospital personnel. In an attempt to overcome these problems we have designed and constructed a production facility for capsules in which 1311 is packaged. Because of the extreme precautions necessary in handling radioactive compounds, encapsulation of radioactive materials requires specifically designed production techniques, special instrumentation and unique quality control procedures that are not encountered in the standard capsule production processes in the pharmaceutical industry

The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF

International Nuclear Information System (INIS)

Casey, D. T.; Frenje, J. A.; Seguin, F. H.; Li, C. K.; Rosenberg, M. J.; Rinderknecht, H.; Manuel, M. J.-E.; Gatu Johnson, M.; Schaeffer, J. C.; Frankel, R.; Sinenian, N.; Childs, R. A.; Petrasso, R. D.; Glebov, V. Yu.; Sangster, T. C.; Burke, M.; Roberts, S.

2011-01-01

A magnetic recoil spectrometer (MRS) has been built and successfully used at OMEGA for measurements of down-scattered neutrons (DS-n), from which an areal density in both warm-capsule and cryogenic-DT implosions have been inferred. Another MRS is currently being commissioned on the National Ignition Facility (NIF) for diagnosing low-yield tritium-hydrogen-deuterium implosions and high-yield DT implosions. As CR-39 detectors are used in the MRS, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). The coincidence counting technique was developed to reduce these types of background tracks to the required level for the DS-n measurements at OMEGA and the NIF. Using this technique, it has been demonstrated that the number of background tracks is reduced by a couple of orders of magnitude, which exceeds the requirement for the DS-n measurements at both facilities.

The coincidence counting technique for orders of magnitude background reduction in data obtained with the magnetic recoil spectrometer at OMEGA and the NIF.

Science.gov (United States)

Casey, D T; Frenje, J A; Séguin, F H; Li, C K; Rosenberg, M J; Rinderknecht, H; Manuel, M J-E; Gatu Johnson, M; Schaeffer, J C; Frankel, R; Sinenian, N; Childs, R A; Petrasso, R D; Glebov, V Yu; Sangster, T C; Burke, M; Roberts, S

2011-07-01

A magnetic recoil spectrometer (MRS) has been built and successfully used at OMEGA for measurements of down-scattered neutrons (DS-n), from which an areal density in both warm-capsule and cryogenic-DT implosions have been inferred. Another MRS is currently being commissioned on the National Ignition Facility (NIF) for diagnosing low-yield tritium-hydrogen-deuterium implosions and high-yield DT implosions. As CR-39 detectors are used in the MRS, the principal sources of background are neutron-induced tracks and intrinsic tracks (defects in the CR-39). The coincidence counting technique was developed to reduce these types of background tracks to the required level for the DS-n measurements at OMEGA and the NIF. Using this technique, it has been demonstrated that the number of background tracks is reduced by a couple of orders of magnitude, which exceeds the requirement for the DS-n measurements at both facilities.

Preparing for polar-drive ignition on the National Ignition Facility

OpenAIRE

McKenty P.W.; Collins T.J.B.; Marozas J.A.; Kessler T.J.; Zuegel J.D.; Shoup M.J.; Craxton R.S.; Marshall F.J.; Shvydky A.; Skupsky S.; Goncharov V.N.; Radha P.B.; Epstein R.; Sangster T.C.; Meyerhofer D.D.

2013-01-01

The implementation of polar drive (PD) at the National Ignition Facility (NIF) will enable the execution of direct-drive implosions while the facility is configured for x-ray drive. The Laboratory for Laser Energetics (LLE), in collaboration with LLNL, LANL and GA, is implementing PD on the NIF. LLE has designed and participates in the use of PD implosions for diagnostic commissioning on the NIF. LLE has an active experimental campaign to develop PD in both warm and cryogenic target experimen...

Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA

Science.gov (United States)

Regan, S. P.; Goncharov, V. N.; Igumenshchev, I. V.; Sangster, T. C.; Betti, R.; Bose, A.; Boehly, T. R.; Bonino, M. J.; Campbell, E. M.; Cao, D.; Collins, T. J. B.; Craxton, R. S.; Davis, A. K.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Forrest, C. J.; Frenje, J. A.; Froula, D. H.; Gatu Johnson, M.; Glebov, V. Yu.; Harding, D. R.; Hohenberger, M.; Hu, S. X.; Jacobs-Perkins, D.; Janezic, R.; Karasik, M.; Keck, R. L.; Kelly, J. H.; Kessler, T. J.; Knauer, J. P.; Kosc, T. Z.; Loucks, S. J.; Marozas, J. A.; Marshall, F. J.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Michel, D. T.; Myatt, J. F.; Obenschain, S. P.; Petrasso, R. D.; Radha, P. B.; Rice, B.; Rosenberg, M. J.; Schmitt, A. J.; Schmitt, M. J.; Seka, W.; Shmayda, W. T.; Shoup, M. J.; Shvydky, A.; Skupsky, S.; Solodov, A. A.; Stoeckl, C.; Theobald, W.; Ulreich, J.; Wittman, M. D.; Woo, K. M.; Yaakobi, B.; Zuegel, J. D.

2016-07-01

A record fuel hot-spot pressure Phs=56 ±7 Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ˜60 % of the value required for ignition [A. Bose et al., Phys. Rev. E 93, LM15119ER (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

Explosion-Induced Implosions of Cylindrical Shell Structures

Science.gov (United States)

Ikeda, C. M.; Duncan, J. H.

2010-11-01

An experimental study of the explosion-induced implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and are placed in a large water-filled pressure vessel. The vessel is then pressurized to various levels P∞=αPc, where Pc is the natural implosion pressure of the model and α is a factor that ranges from 0.1 to 0.9. An explosive is then set off at various standoff distances, d, from the model center line, where d varies from R to 10R and R is the maximum radius of the explosion bubble. High-speed photography (27,000 fps) was used to observe the explosion and resulting shell structure implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 6 positions. The cylindrical models were made from aluminum (diameter D = 39.1 mm, wall thickness t = 0.89 mm, length L = 240 mm) and brass (D = 16.7 mm, t = 0.36 mm, L=152 mm) tubes. The pressure records are interpreted in light of the high-speed movies. It is found that the implosion is induced by two mechanisms: the shockwave generated by the explosion and the jet formed during the explosion-bubble collapse. Whether an implosion is caused by the shockwave or the jet depends on the maximum bubble diameter and the standoff distance.

Characterization of a WESF [Waste Encapsulation and Storage Facility] cesium chloride capsule after fifteen months service in a dry operation/wet storage commercial irradiator

International Nuclear Information System (INIS)

Kjarmo, H.E.; Tingey, G.L.

1988-08-01

After 15 months of service, a Hanford Waste Encapsulation and Storage Facility (WESF) 137 Cs gamma source capsule was removed for examination from a commercial irradiator at Radiation Sterilizers Incorporated (RSI), Westerville, Ohio. The examination was conducted by Pacific Northwest Laboratory and was the first study of a 137 Cs source capsule after use in a commercial dry operation/wet storage (dry/wet) irradiator. The capsule was cycled 3327 times during the 15-month period with steady-state temperature differences ranging from 70 to 82/degree/C during the air-to-water cycle. The capsule was examined to determine the amount of corrosion that had occurred during this period and to determine if any degradation of the container was evident as the result of thermal cycling. Metallographic examinations were performed on sections that were removed from the inner capsule wall and bottom end cap and the outer capsule bottom end cap weld. The three regions of the inner capsule that were examined for corrosion were the salt/void interface, midwall, and bottom (including the end cap weld). The amount of corrosion measured (0.0002 to 0.0007 in.) is comparable to the corrosion produced (about 0.001 in.) during the melt-cast filling of a capsule. No observable effects of irradiator operation were found during this examination. Consequently, based on this examination, no degradation of WESF 137 Cs capsules is expected when they are used in irradiators similar to the RSI irradiator. 9 refs., 12 figs., 2 tabs

Three-dimensional hydrodynamics of the deceleration stage in inertial confinement fusion

Energy Technology Data Exchange (ETDEWEB)

Weber, C. R., E-mail: weber30@llnl.gov; Clark, D. S.; Cook, A. W.; Eder, D. C.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Jones, O. S.; Marinak, M. M.; Milovich, J. L.; Patel, P. K.; Robey, H. F.; Salmonson, J. D.; Sepke, S. M.; Thomas, C. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2015-03-15

The deceleration stage of inertial confinement fusion implosions is modeled in detail using three-dimensional simulations designed to match experiments at the National Ignition Facility. In this final stage of the implosion, shocks rebound from the center of the capsule, forming the high-temperature, low-density hot spot and slowing the incoming fuel. The flow field that results from this process is highly three-dimensional and influences many aspects of the implosion. The interior of the capsule has high-velocity motion, but viscous effects limit the range of scales that develop. The bulk motion of the hot spot shows qualitative agreement with experimental velocity measurements, while the variance of the hot spot velocity would broaden the DT neutron spectrum, increasing the inferred temperature by 400–800 eV. Jets of ablator material are broken apart and redirected as they enter this dynamic hot spot. Deceleration stage simulations using two fundamentally different rad-hydro codes are compared and the flow field is found to be in good agreement.

Three-dimensional hydrodynamics of the deceleration stage in inertial confinement fusion

International Nuclear Information System (INIS)

Weber, C. R.; Clark, D. S.; Cook, A. W.; Eder, D. C.; Haan, S. W.; Hammel, B. A.; Hinkel, D. E.; Jones, O. S.; Marinak, M. M.; Milovich, J. L.; Patel, P. K.; Robey, H. F.; Salmonson, J. D.; Sepke, S. M.; Thomas, C. A.

2015-01-01

The deceleration stage of inertial confinement fusion implosions is modeled in detail using three-dimensional simulations designed to match experiments at the National Ignition Facility. In this final stage of the implosion, shocks rebound from the center of the capsule, forming the high-temperature, low-density hot spot and slowing the incoming fuel. The flow field that results from this process is highly three-dimensional and influences many aspects of the implosion. The interior of the capsule has high-velocity motion, but viscous effects limit the range of scales that develop. The bulk motion of the hot spot shows qualitative agreement with experimental velocity measurements, while the variance of the hot spot velocity would broaden the DT neutron spectrum, increasing the inferred temperature by 400–800 eV. Jets of ablator material are broken apart and redirected as they enter this dynamic hot spot. Deceleration stage simulations using two fundamentally different rad-hydro codes are compared and the flow field is found to be in good agreement

Radiochemical determination of Inertial Confinement Fusion capsule compression at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Shaughnessy, D. A., E-mail: shaughnessy2@llnl.gov; Moody, K. J.; Gharibyan, N.; Grant, P. M.; Gostic, J. M.; Torretto, P. C.; Wooddy, P. T.; Bandong, B. B.; Cerjan, C. J.; Hagmann, C. A.; Caggiano, J. A.; Yeamans, C. B.; Bernstein, L. A.; Schneider, D. H. G.; Henry, E. A.; Fortner, R. J. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94551 (United States); Despotopulos, J. D. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94551 (United States); Radiochemistry Program, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States)

2014-06-15

We describe a radiochemical measurement of the ratio of isotope concentrations produced in a gold hohlraum surrounding an Inertial Confinement Fusion capsule at the National Ignition Facility (NIF). We relate the ratio of the concentrations of (n,γ) and (n,2n) products in the gold hohlraum matrix to the down-scatter of neutrons in the compressed fuel and, consequently, to the fuel's areal density. The observed ratio of the concentrations of {sup 198m+g}Au and {sup 196g}Au is a performance signature of ablator areal density and the fuel assembly confinement time. We identify the measurement of nuclear cross sections of astrophysical importance as a potential application of the neutrons generated at the NIF.

Programmed temperature control of capsule in irradiation test with personal computer at JMTR

International Nuclear Information System (INIS)

Saito, H.; Uramoto, T.; Fukushima, M.; Obata, M.; Suzuki, S.; Nakazaki, C.; Tanaka, I.

1992-01-01

The capsule irradiation facility is one of various equipments employed at the Japan Materials Testing Reactor (JMTR). The capsule facility has been used in irradiation tests of both nuclear fuels and materials. The capsule to be irradiated consists of the specimen, the outer tube and inner tube with a annular space between them. The temperature of the specimen is controlled by varying the degree of pressure (below the atmospheric pressure) of He gas in the annular space (vacuum-controlled). Beside this, in another system the temperature of the specimen is controlled with electric heaters mounted around the specimen (heater-controlled). The use of personal computer in the capsule facility has led to the development of a versatile temperature control system at the JMTR. Features of this newly-developed temperature control system lie in the following: the temperature control mode for a operation period can be preset prior to the operation; and the vacuum-controlled irradiation facility can be used in cooperation with the heater-controlled. The introduction of personal computer has brought in automatic heat-up and cool-down operations of the capsule, setting aside the hand-operated jobs which had been conducted by the operators. As a result of this, the various requirements seeking a higher accuracy and efficiency in the irradiation can be met by fully exploiting the capabilities incorporated into the facility which allow the cyclic or delicate changes in the temperature. This paper deals with a capsule temperature control system with personal computer. (author)

Ignition capsules with aerogel-supported liquid DT fuel for the National Ignition Facility

Directory of Open Access Journals (Sweden)

Ho D.D.-M.

2013-11-01

Full Text Available For high repetition-rate fusion power plant applications, capsules with aerogel-supported liquid DT fuel can have much reduced fill time compared to β-layering a solid DT fuel layer. The melting point of liquid DT can be lowered once liquid DT is embedded in an aerogel matrix, and the DT vapor density is consequently closer to the desired density for optimal capsule design requirement. We present design for NIF-scale aerogel-filled capsules based on 1-D and 2-D simulations. An optimal configuration is obtained when the outer radius is increased until the clean fuel fraction is within 65 – 75% at peak velocity. A scan (in ablator and fuel thickness parameter space is used to optimize the capsule configurations. The optimized aerogel-filled capsule has good low-mode robustness and acceptable high-mode mix.

Implosion heating studies in the Scylla 1B, implosion heating, and staged theta-pinch experiments

International Nuclear Information System (INIS)

Gribble, R.F.; Hammel, J.E.; Henins, I.; Jahoda, F.C.; Kristal, R.; Linford, R.K.; Marshall, J.; McKenna, K.F.; Sherwood, A.R.; Thomas, K.S.

1975-01-01

Three experiments designed to study various aspects of implosion heating in the plasma density range (10 14 -10 16 cm -3 ) used in present theta pinches are described. Initial plasma studies show that, provided a sufficiently high pre-ionization level (>10 14 cm -3 ) is achieved, plasma behaviour is qualitatively the same over a range of two in initial magnetic field rise and a range of four in initial gas fill. The implosion phase is characterized by rapid changes in magnetic-field diffusion rates, the plasma resistivity decreasing rapidly with time. During the implosion some of the plasma density observed is moving ahead of the magnetic piston. Magnetic-field gradients occur in the region outside the area of measurable plasma density implying the presence of hot, low-density plasma in this region. In experiments where the external magnetic field decreases before the maximum compression of the plasma column, secondary breakdown occurs at the discharge tube wall which slows the rate at which magnetic flux diffuses out of the discharge tube. (author)

Design and fabrication of non-instrumented capsule

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Sung; Lee, Jeong Young; Kim, Joon Yeon; Lee, Sung Ho; Ji, Dae Young; Kim, Suk Hoon; Ahn, Sung Ho [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-04-01

The use of non-instrumented capsule designed and fabricated in this time is for the evaluation of material irradiation performance, it is to be installed in the inner core of HANARO. The design process of non-instrumented capsule was accomplished by the decision of the quality of material and the shape, thermal analysis, structural analysis. The temperature of the specimen and the stress in capsule during irradiation test was calculated by the thermal analysis and the structural analysis. GGENGTC code and ABAQUS code were used for the calculation of non-instrumented capsule. In case of installing the capsule in irradiation hole, the coolant flow rate and the pressure drop in the hole is changed, which will affect the coolant flow rate of the fuel region. Eventually the coolant flow rate outside capsule have to be restricted to the allowable range. In order to obtain the required pressure drop, the flow rate control mechanism, end plate and orifice ring were used in this test. The test results are compared with 36-element fuel pressure drop data which AECL performed by the SCTR facility.

Design and fabrication of non-instrumented capsule

International Nuclear Information System (INIS)

Kim, Yong Sung; Lee, Jeong Young; Kim, Joon Yeon; Lee, Sung Ho; Ji, Dae Young; Kim, Suk Hoon; Ahn, Sung Ho

1995-04-01

The use of non-instrumented capsule designed and fabricated in this time is for the evaluation of material irradiation performance, it is to be installed in the inner core of HANARO. The design process of non-instrumented capsule was accomplished by the decision of the quality of material and the shape, thermal analysis, structural analysis. The temperature of the specimen and the stress in capsule during irradiation test was calculated by the thermal analysis and the structural analysis. GGENGTC code and ABAQUS code were used for the calculation of non-instrumented capsule. In case of installing the capsule in irradiation hole, the coolant flow rate and the pressure drop in the hole is changed, which will affect the coolant flow rate of the fuel region. Eventually the coolant flow rate outside capsule have to be restricted to the allowable range. In order to obtain the required pressure drop, the flow rate control mechanism, end plate and orifice ring were used in this test. The test results are compared with 36-element fuel pressure drop data which AECL performed by the SCTR facility

Predictions of the microstructural contribution to instability seeding in beryllium ICF capsules

International Nuclear Information System (INIS)

Hoffman, Nelson M.; Swift, Damian C.

2004-01-01

The constitutive properties of beryllium are anisotropic. During the implosion of an inertial confinement fusion capsule, it is possible for instabilities to be seeded from the microstructure. We are using experiment and theory to place constraints on the microstructure and loading history. The relation between surface roughness and amplitude of ablative Rayleigh-Taylor instabilities has been characterized well. Here we present a method of relating the microstructure to an equivalent surface roughness, using continuum mechanical simulations of shock waves in polycrystalline beryllium. Beryllium was treated using a single-crystal plasticity model developed using ab initio quantum mechanics for the equation of state and elasticity, and laser-driven shock wave measurements to calibrate representations of dislocation and disclination dynamics

Positron radiography of ignition-relevant ICF capsules

Science.gov (United States)

Williams, G. J.; Chen, Hui; Field, J. E.; Landen, O. L.; Strozzi, D. J.

2017-12-01

Laser-generated positrons are evaluated as a probe source to radiograph in-flight ignition-relevant inertial confinement fusion capsules. Current ultraintense laser facilities are capable of producing 2 × 1012 relativistic positrons in a narrow energy bandwidth and short time duration. Monte Carlo simulations suggest that the unique characteristics of such positrons allow for the reconstruction of both capsule shell radius and areal density between 0.002 and 2 g/cm2. The energy-downshifted positron spectrum and angular scattering of the source particles are sufficient to constrain the conditions of the capsule between preshot and stagnation. We evaluate the effects of magnetic fields near the capsule surface using analytic estimates where it is shown that this diagnostic can tolerate line integrated field strengths of 100 T mm.

Hydrodynamic analysis of laser-driven cylindrical implosions

Energy Technology Data Exchange (ETDEWEB)

Ramis, R. [E.T.S.I. Aeronáuticos, Universidad Politécnica de Madrid (Spain)

2013-08-15

Three-dimensional hydrodynamic simulations are performed to study laser-driven cylindrical implosions in the context of experiments (F. Perez et al., Plasma Phys. Controlled Fusion 51, 124035 (2009)) carried out at the Rutherford Appleton Laboratory in the framework of the HiPER project. The analysis is carried out by using the 3D version of the hydrocode MULTI (R. Ramis et al., Comput. Phys. Commun. 49, 475-505 (1988)). The influence of the main laser parameters on implosion performance and symmetry is consistently studied and compared with the results of 2D analysis. Furthermore, the effects of uncertainties in laser irradiation (pointing, focusing, power balance, and time jitter) on implosion performance (average peak density and temperature) are studied by means of statistical analysis.

Safety evaluation for packaging (onsite) singly encapsulated cesium chloride capsules

International Nuclear Information System (INIS)

Smyth, W.W.

1997-01-01

Three nonstandard Waste Encapsulation and Storage Facility (WESF) cesium chloride capsules are being shipped from WESF (225B building) to the 324 building. They would normally be shipped in the Beneficial Uses Shipping System (BUSS) cask under its US Department of Energy (DOE) license (DOE 1996), but these capsules are nonstandard: one has a damaged or defective weld in the outer layer of encapsulation, and two have the outer encapsulation removed. The 3 capsules, along with 13 other capsules, will be overpacked in the 324 building to meet the requirements for storage in WESF's pool

Opportunities for Suborbital Space and Atmospheric Research Facilities on Blue Origin's New Shepard Crew Capsule

Science.gov (United States)

Wagner, E.; DeForest, C. E.

2016-12-01

With the emergence of the commercial space industry, researchers now have more options than ever for conducting research aboard space-going platforms. Blue Origin's New Shepard spacecraft offers a large-format crew capsule, capable of carrying a wide range of high-altitude and microgravity payloads above the Karman Line (100 km). With high flight rates and short approval timelines, investigators are able to use data from one flight to refine research objectives and quickly fly again, closing the loop on the scientific method and rapidly advancing technology development. Young investigators have ready access to real-world experiences in building flight hardware, and more involved missions are using this low-barrier environment to raise Technology Readiness Level of components or subsystems. This talk will introduce the standard interfaces and operations for payloads already flying within the New Shepard capsule. We will also explore opportunities for custom facilities that would allow researchers access to the space environment at altitudes between 60 and 100 km. We will discuss the unique science that can be conducted in this region, above where balloons can dwell, but below satellite orbits, including investigations in heliophysics, planetary science, and aeronomy.

Some recent efforts toward high density implosions

International Nuclear Information System (INIS)

McClellan, G.E.

1980-01-01

Some recent Livermore efforts towards achieving high-density implosions are presented. The implosion dynamics necessary to compress DT fuel to 10 to 100 times liquid density are discussed. Methods of diagnosing the maximum DT density for a specific design are presented along with results to date. The dynamics of the double-shelled target with an exploding outer shell are described, and some preliminary experimental results are presented

A self-similar isochoric implosion for fast ignition

International Nuclear Information System (INIS)

Clark, D.S.; Tabak, M.

2007-01-01

Various gain models have shown the potentially great advantages of fast ignition (FI) inertial confinement fusion (ICF) over its conventional hot spot ignition counterpart (e.g. Atzeni S. 1999 Phys. Plasmas 6 3316; Tabak M. et al 2006 Fusion Sci. Technol. 49 254). These gain models, however, all assume nearly uniform density fuel assemblies. In contrast, conventional ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hot spot. Hence, to realize fully the advantages of FI, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hot spots. Here, it is shown that a self-similar spherical implosion of the type originally studied by Guderley (1942 Luftfahrtforschung 19 302) may be employed to yield precisely such quasi-isochoric imploded states. The difficulty remains, however, of accessing these self-similarly imploding configurations from initial conditions representing an actual ICF target, namely a uniform, solid-density shell at rest. Furthermore, these specialized implosions must be realized for practicable drive parameters and at the scales and energies of interest in ICF. A direct-drive implosion scheme is presented which meets all of these requirements and reaches a nearly isochoric assembled density of 300 g cm -3 and areal density of 2.4 g cm -2 using 485 kJ of laser energy

Phenomenological modeling of turbulence in Z-pinch implosions

International Nuclear Information System (INIS)

Thornhill, J.W.; Whitney, K.G.; Deeney, C.; LePell, P.D.

1994-01-01

A phenomenological investigation into the effects of magnetohydrodynamic (MHD) turbulence on the initial stagnation dynamics of aluminum wire array and argon gas puff Z-pinch implosions is performed. The increases that turbulence produces in the plasma viscosity, heat conductivity, and electrical resistivity are modeled by using multipliers for these quantities in one-dimensional (1-D) MHD calculations. The major effect of these increases is to soften the 1-D implosions by decreasing the densities that are achieved on axis at stagnation. As a consequence, a set of multipliers can be found that reasonably duplicates the average electron temperatures, ion densities, and mass of the K-shell emission region that were measured at stagnation for a variety of Physics International aluminum wire array and argon gas puff experiments. It is determined that the dependence of these measured quantities on the multipliers is weak once a level of enhancement is reached, where agreement between calculations and experiments is attained. The scaling of K-shell yield with load mass for a fixed implosion velocity is then reexamined, and the minimum load mass needed to efficiently produce K-shell emission by thermalization of kinetic energy is calculated for aluminum and argon using this phenomenological soft implosion modeling. The results show an upward shift in the minimum mass by a factor of 6 when compared to the original nonturbulent hard implosion calculations

Shock wave, fluid instability and implosion studies with a kinetic particle approach

Science.gov (United States)

Sagert, Irina; Even, Wesley P.; Strother, Terrance T.

2016-10-01

Many problems in laboratory plasma physics are subject to flows that move between the continuum and the kinetic regime. The correct description of these flows is crucial in order to capture their impact on the system's dynamical evolution. Examples are capsule implosions in inertial confinement fusion (ICF). Although their dynamics is predominantly shaped by shock waves and fluid instabilities, non-equilibrium flows in form of deuterium/tritium ions have been shown to play a significant role. We present recent studies with our Monte Carlo kinetic particle code that is designed to capture continuum and kinetic flows in large physical systems with possible applications in ICF studies. Discussed results will include standard shock wave and fluid instability tests and simulations that are adapted towards future ICF studies with comparisons to hydrodynamic simulations. This work used the Wolf TriLAB Capacity Cluster at LANL. I.S. acknowledges support through a Director's fellowship (20150741PRD3) from Los Alamos National Laboratory.

Proton Radiography of Spontaneous Fields, Plasma Flows and Dynamics in X-Ray Driven Inertial-Confinement Fusion Implosions

Science.gov (United States)

Li, C. K.; Seguin, F. H.; Frenje, J. A.; Rosenberg, M.; Zylstra, A. B.; Rinderknecht, H. G.; Petrasso, R. D.; Amendt, P. A.; Landen, O. L.; Town, R. P. J.; Betti, R.; Knauer, J. P.; Meyerhofer, D. D.; Back, C. A.; Kilkenny, J. D.; Nikroo, A.

2010-11-01

Backlighting of x-ray-driven implosions in empty hohlraums with mono-energetic protons on the OMEGA laser facility has allowed a number of important phenomena to be observed. Several critical parameters were determined, including plasma flow, three types of spontaneous electric fields and megaGauss magnetic fields. These results provide insight into important issues in indirect-drive ICF. Even though the cavity is effectively a Faraday cage, the strong, local fields inside the hohlraum can affect laser-plasma instabilities, electron distributions and implosion symmetry. They are of fundamental scientific importance for a range of new experiments at the frontiers of high-energy-density physics. Future experiments designed to characterize the field formation and evolution in low-Z gas fill hohlraums will be discussed.

The Los Alamos foil implosion project

International Nuclear Information System (INIS)

Brownell, J.; Parker, J.; Bartsch, R.; Benage, J.; Bowers, R.; Cochrane, J.; Forman, P.; Goforth, J.; Greene, A.; Kruse, H.

1993-01-01

The goal of the Los Alamos foil implosion project is to produce an intense (>100 TW), multi-megajoule, laboratory soft x-ray source for material studies and fusion experiments. The concept involves the implosion of annular, current-carrying, cylindrical metallic plasmas via their self-magnetic forces. The project features inductive storage systems using both capacitor banks and high explosive-driven flux compression generators as prime energy sources. Fast opening switches are employed to shorten the electrical pulses. The program will be described and activities to date will be summarized

A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF.

Science.gov (United States)

Zylstra, A B; Gatu Johnson, M; Frenje, J A; Séguin, F H; Rinderknecht, H G; Rosenberg, M J; Sio, H W; Li, C K; Petrasso, R D; McCluskey, M; Mastrosimone, D; Glebov, V Yu; Forrest, C; Stoeckl, C; Sangster, T C

2014-06-01

A compact spectrometer for measurements of the primary deuterium-tritium neutron spectrum has been designed and implemented on the OMEGA laser facility [T. Boehly et al., Opt. Commun. 133, 495 (1997)]. This instrument uses the recoil spectrometry technique, where neutrons produced in an implosion elastically scatter protons in a plastic foil, which are subsequently detected by a proton spectrometer. This diagnostic is currently capable of measuring the yield to ~±10% accuracy, and mean neutron energy to ~±50 keV precision. As these compact spectrometers can be readily placed at several locations around an implosion, effects of residual fuel bulk flows during burn can be measured. Future improvements to reduce the neutron energy uncertainty to ±15-20 keV are discussed, which will enable measurements of fuel velocities to an accuracy of ~±25-40 km/s.

Determination of travel time capsules hydraulic rabbit system channel 2 (JBB 02) at the G.A. Siwabessy reactor

International Nuclear Information System (INIS)

Sutrisno; Sunarko; Elisabeth Ratnawati

2014-01-01

Rabbit System is an irradiation facilities used for research on neutron activation. There are two types of Rabbit Systems including 4 pieces Rabbit Hydraulic Systems (JBB01 - JBB04) and Rabbit Pneumatic Systems (JBB05). Irradiation facility of hydraulic rabbit system is irradiation facility with media delivery in the form of capsules. Travel time delivery and the return capsule in hydraulic rabbit system facility depends on the magnitude of the observed flow rate on flow measurement instruments for water circulation. To determine the travel time should be observed flow rates varied by opening the valve (JBB02 AA007), so the delivery time and the return capsule in the rabbit facility hydraulic system can be known. Observations made from the results obtained travel time capsule delivery poly ethylene (PE) of the isotope cell to irradiation position appropriate to the graph Y=57,67 e -0,139.x , for capsules Aluminum (Al) appropriate graph Y= 68,178 e -0,189.x , while the travel time of the return capsule poly ethylene (PE) from the irradiation position to the isotope cell appropriate graph Y=56,459 e -13.x , for capsules Al appropriate graph Y= 65,51 e -183.x this result can be used as a reference for determining the travel time desired by the operator. (author)

Demonstration of Fuel Hot-Spot Pressure in Excess of 50 Gbar for Direct-Drive, Layered Deuterium-Tritium Implosions on OMEGA.

Science.gov (United States)

Regan, S P; Goncharov, V N; Igumenshchev, I V; Sangster, T C; Betti, R; Bose, A; Boehly, T R; Bonino, M J; Campbell, E M; Cao, D; Collins, T J B; Craxton, R S; Davis, A K; Delettrez, J A; Edgell, D H; Epstein, R; Forrest, C J; Frenje, J A; Froula, D H; Gatu Johnson, M; Glebov, V Yu; Harding, D R; Hohenberger, M; Hu, S X; Jacobs-Perkins, D; Janezic, R; Karasik, M; Keck, R L; Kelly, J H; Kessler, T J; Knauer, J P; Kosc, T Z; Loucks, S J; Marozas, J A; Marshall, F J; McCrory, R L; McKenty, P W; Meyerhofer, D D; Michel, D T; Myatt, J F; Obenschain, S P; Petrasso, R D; Radha, P B; Rice, B; Rosenberg, M J; Schmitt, A J; Schmitt, M J; Seka, W; Shmayda, W T; Shoup, M J; Shvydky, A; Skupsky, S; Solodov, A A; Stoeckl, C; Theobald, W; Ulreich, J; Wittman, M D; Woo, K M; Yaakobi, B; Zuegel, J D

2016-07-08

A record fuel hot-spot pressure P_{hs}=56±7  Gbar was inferred from x-ray and nuclear diagnostics for direct-drive inertial confinement fusion cryogenic, layered deuterium-tritium implosions on the 60-beam, 30-kJ, 351-nm OMEGA Laser System. When hydrodynamically scaled to the energy of the National Ignition Facility, these implosions achieved a Lawson parameter ∼60% of the value required for ignition [A. Bose et al., Phys. Rev. E 93, 011201(R) (2016)], similar to indirect-drive implosions [R. Betti et al., Phys. Rev. Lett. 114, 255003 (2015)], and nearly half of the direct-drive ignition-threshold pressure. Relative to symmetric, one-dimensional simulations, the inferred hot-spot pressure is approximately 40% lower. Three-dimensional simulations suggest that low-mode distortion of the hot spot seeded by laser-drive nonuniformity and target-positioning error reduces target performance.

A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF.

Science.gov (United States)

Rinderknecht, H G; Johnson, M Gatu; Zylstra, A B; Sinenian, N; Rosenberg, M J; Frenje, J A; Waugh, C J; Li, C K; Sèguin, F H; Petrasso, R D; Rygg, J R; Kimbrough, J R; MacPhee, A; Collins, G W; Hicks, D; Mackinnon, A; Bell, P; Bionta, R; Clancy, T; Zacharias, R; Döppner, T; Park, H S; LePape, S; Landen, O; Meezan, N; Moses, E I; Glebov, V U; Stoeckl, C; Sangster, T C; Olson, R; Kline, J; Kilkenny, J

2012-10-01

The particle-time-of-flight (pTOF) diagnostic, fielded alongside a wedge range-filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted ρR measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT exploding pusher, and D(3)He implosions using DD or DT neutrons with an accuracy better than ±70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D(3)He-filled surrogate implosions using D(3)He protons and DD-neutrons, respectively.

Effectiveness of Cranberry Capsules to Prevent Urinary Tract Infections in Vulnerable Older Persons: A Double-Blind Randomized Placebo-Controlled Trial in Long-Term Care Facilities

Science.gov (United States)

Caljouw, Monique A A; van den Hout, Wilbert B; Putter, Hein; Achterberg, Wilco P; Cools, Herman J M; Gussekloo, Jacobijn

2014-01-01

Objectives To determine whether cranberry capsules prevent urinary tract infection (UTI) in long-term care facility (LTCF) residents. Design Double-blind randomized placebo-controlled multicenter trial. Setting Long-term care facilities (LTCFs). Participants LTCF residents (N = 928; 703 women, median age 84). Measurements Cranberry and placebo capsules were taken twice daily for 12 months. Participants were stratified according to UTI risk (risk factors included long-term catheterization, diabetes mellitus, ≥1 UTI in preceding year). Main outcomes were incidence of UTI according to a clinical definition and a strict definition. Results In participants with high UTI risk at baseline (n = 516), the incidence of clinically defined UTI was lower with cranberry capsules than with placebo (62.8 vs 84.8 per 100 person-years at risk, P = .04); the treatment effect was 0.74 (95% confidence interval (CI) = 0.57–0.97). For the strict definition, the treatment effect was 1.02 (95% CI = 0.68–1.55). No difference in UTI incidence between cranberry and placebo was found in participants with low UTI risk (n = 412). Conclusion In LTCF residents with high UTI risk at baseline, taking cranberry capsules twice daily reduces the incidence of clinically defined UTI, although it does not reduce the incidence of strictly defined UTI. No difference in incidence of UTI was found in residents with low UTI risk. PMID:25180378

Progress toward development of a platform for studying burn in the presence of mix on the National Ignition Facility

Science.gov (United States)

Murphy, T. J.; Kyrala, G. A.; Bradley, P. A.; Krasheninnikova, N. S.; Cobble, J. A.; Tregillis, I. L.; Obrey, K. A. D.; Hsu, S. C.; Shah, R. C.; Hakel, P.; Kline, J. L.; Grim, G. P.; Baumgaertel, J. A.; Schmitt, M. J.; Kanzleiter, R. J.; Batha, S. H.

2013-10-01

Mix of shell material into ICF capsule fuel can degrade implosion performance through a number of mechanisms. One way is by dilution of the fusion fuel, which affects performance by an amount that is dependent on the degree of mix at the atomic level. Experiments are underway to quantify the mix of shell material into fuel using directly driven capsules on the National Ignition Facility. Deuterated plastic shells will be utilized with tritium fill so that the production of DT neutrons is indicative of mix at the atomic level. Neutron imaging will locate the burn region and spectroscopic imaging of the doped layers will reveal the location, temperature, and density of the shell material. Correlation of the two will be used to determine the degree of atomic mixing of the shell into the fuel and will be compared to models. This talk will review progress toward the development of an experimental platform to measure burn in the presence of measured mix. This work is supported by US DOE/NNSA, performed at LANL, operated by LANS LLC under contract DE-AC52-06NA25396.

Compact wire array sources: power scaling and implosion physics.

Energy Technology Data Exchange (ETDEWEB)

Serrano, Jason Dimitri; Chuvatin, Alexander S. (Laboratoire du Centre National de la Recherche Scientifique Ecole Polytechnique, Palaiseau, France); Jones, M. C.; Vesey, Roger Alan; Waisman, Eduardo M.; Ivanov, V. V. (University of Nevada - Reno, Reno, NV); Esaulov, Andrey A. (University of Nevada - Reno, Reno, NV); Ampleford, David J.; Cuneo, Michael Edward; Kantsyrev, Victor Leonidovich (University of Nevada - Reno, Reno, NV); Coverdale, Christine Anne; Rudakov, L. I. (Icarus Research, Bethesda, MD); Jones, Brent Manley; Safronova, Alla S. (University of Nevada - Reno, Reno, NV); Vigil, Marcelino Patricio

2008-09-01

A series of ten shots were performed on the Saturn generator in short pulse mode in order to study planar and small-diameter cylindrical tungsten wire arrays at {approx}5 MA current levels and 50-60 ns implosion times as candidates for compact z-pinch radiation sources. A new vacuum hohlraum configuration has been proposed in which multiple z pinches are driven in parallel by a pulsed power generator. Each pinch resides in a separate return current cage, serving also as a primary hohlraum. A collection of such radiation sources surround a compact secondary hohlraum, which may potentially provide an attractive Planckian radiation source or house an inertial confinement fusion fuel capsule. Prior to studying this concept experimentally or numerically, advanced compact wire array loads must be developed and their scaling behavior understood. The 2008 Saturn planar array experiments extend the data set presented in Ref. [1], which studied planar arrays at {approx}3 MA, 100 ns in Saturn long pulse mode. Planar wire array power and yield scaling studies now include current levels directly applicable to multi-pinch experiments that could be performed on the 25 MA Z machine. A maximum total x-ray power of 15 TW (250 kJ in the main pulse, 330 kJ total yield) was observed with a 12-mm-wide planar array at 5.3 MA, 52 ns. The full data set indicates power scaling that is sub-quadratic with load current, while total and main pulse yields are closer to quadratic; these trends are similar to observations of compact cylindrical tungsten arrays on Z. We continue the investigation of energy coupling in these short pulse Saturn experiments using zero-dimensional-type implosion modeling and pinhole imaging, indicating 16 cm/?s implosion velocity in a 12-mm-wide array. The same phenomena of significant trailing mass and evidence for resistive heating are observed at 5 MA as at 3 MA. 17 kJ of Al K-shell radiation was obtained in one Al planar array fielded at 5.5 MA, 57 ns and we

Characterizing Hohlraum Plasma Conditions at the National Ignition Facility (NIF) Using X-ray Spectroscopy

Science.gov (United States)

Barrios, Maria Alejandra

2015-11-01

Improved hohlraums will have a significant impact on increasing the likelihood of indirect drive ignition at the NIF. In indirect-drive Inertial Confinement Fusion (ICF), a high-Z hohlraum converts laser power into a tailored x-ray flux that drives the implosion of a spherical capsule filled with D-T fuel. The x-radiation drive to capsule coupling sets the velocity, adiabat, and symmetry of the implosion. Previous experiments in gas-filled hohlraums determined that the laser-hohlraum energy coupling is 20-25% less than modeled, therefore identifying energy loss mechanisms that reduce the efficacy of the hohlraum drive is central to improving implosion performance. Characterizing the plasma conditions, particularly the plasma electron temperature (Te) , is critical to understanding mechanism that affect the energy coupling such as the laser plasma interactions (LPI), hohlraum x-ray conversion efficiency, and dynamic drive symmetry. The first Te measurements inside a NIF hohlraum, presented here, were achieved using K-shell X-ray spectroscopy of an Mn-Co tracer dot. The dot is deposited on a thin-walled CH capsule, centered on the hohlraum symmetry axis below the laser entrance hole (LEH) of a bottom-truncated hohlraum. The hohlraum x-ray drive ablates the dot and causes it to flow upward, towards the LEH, entering the hot laser deposition region. An absolutely calibrated streaked spectrometer with a line of sight into the LEH records the temporal history of the Mn and Co X-ray emission. The measured (interstage) Lyα/ Heα line ratios for Co and Mn and the Mn-Heα/Co-Heα isoelectronic line ratio are used to infer the local plasma Te from the atomic physics code SCRAM. Time resovled x-ray images perpendicular to the hohlraum axis record the dot expansion and trajectory into the LEH region. The temporal evolution of the measured Te and dot trajectory are compared with simulations from radiation-hydrodynamic codes. This work was performed under the auspices of the U

On the Potential Role of Species Separation in DT Fuels on Implosion Performance

Science.gov (United States)

Amendt, Peter; Bellei, Claudio; Wilks, Scott; Haines, Malcolm; Casey, Dan; Li, C. K.; Petrasso, Richard

2012-10-01

The measurement of strong, self-generated electric fields (1-10 GVolts/m) in imploding capsules [1], their attribution to polarized (plasma) shock fronts [2], and the identification of plasma-enhanced binary species diffusion from barodiffusion and electrodiffusion [3] have led to a growing interest in the potential role of species separation in inertial-confinement-fusion (ICF) thermonuclear fuels. The potential for anomalous heating from transient frictional or resistive drag between D and T across a finite thickness shock front will be assessed and applied towards ignition thresholds and understanding some outstanding anomalies in the Omega implosion database.[4pt] [1] J.R. Rygg et al., Science 319, 1223 (2008); C.K. Li et al., Phys. Rev. Lett. 100, 225001 (2008).[0pt] [2] P.A. Amendt, J.L. Milovich, S.C. Wilks, C.K. Li, R.D. Petrasso and F.H. S'eguin, Plasma Phys. Control. Fusion 51, 124048 (2009).[0pt] [3] P. Amendt, C. Bellei and S.C. Wilks, Phys. Rev. Lett. (to appear).

A compact neutron spectrometer for characterizing inertial confinement fusion implosions at OMEGA and the NIF

Energy Technology Data Exchange (ETDEWEB)

Zylstra, A. B., E-mail: zylstra@mit.edu; Gatu Johnson, M.; Frenje, J. A.; Séguin, F. H.; Rinderknecht, H. G.; Rosenberg, M. J.; Sio, H. W.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); McCluskey, M.; Mastrosimone, D.; Glebov, V. Yu.; Forrest, C.; Stoeckl, C.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2014-06-15

A compact spectrometer for measurements of the primary deuterium-tritium neutron spectrum has been designed and implemented on the OMEGA laser facility [T. Boehly et al., Opt. Commun. 133, 495 (1997)]. This instrument uses the recoil spectrometry technique, where neutrons produced in an implosion elastically scatter protons in a plastic foil, which are subsequently detected by a proton spectrometer. This diagnostic is currently capable of measuring the yield to ∼±10% accuracy, and mean neutron energy to ∼±50 keV precision. As these compact spectrometers can be readily placed at several locations around an implosion, effects of residual fuel bulk flows during burn can be measured. Future improvements to reduce the neutron energy uncertainty to ±15−20 keV are discussed, which will enable measurements of fuel velocities to an accuracy of ∼±25−40 km/s.

WESF cesium capsule behavior at high temperature or during thermal cycling

International Nuclear Information System (INIS)

Tingey, G.L.; Gray, W.J.; Shippell, R.J.; Katayama, Y.B.

1985-06-01

Double-walled stainless steel (SS) capsules prepared for storage of radioactive 137 Cs from defense waste are now being considered for use as sources for commercial irradiation. Cesium was recovered at B-plant from the high-level radioactive waste generated during processing of defense nuclear fuel. It was then purified, converted to the chloride form, and encapsulated at the Hanford Waste Encapsulation and Storage Facility (WESF). The molten cesium chloride salt was encapsulated by pouring it into the inner of two concentric SS cylinders. Each cylinder was fitted with a SS end cap that was welded in place by inert gas-tungsten arc welding. The capsule configuration and dimensions are shown in Figure 1. In a recent review of the safety of these capsules, Tingey, Wheelwright, and Lytle (1984) indicated that experimental studies were continuing to produce long-term corrosion data, to reaffirm capsule integrity during a 90-min fire where capsule temperatures reached 800 0 C, to monitor mechanical properties as a function of time, and to assess the effects of thermal cycling due to periodic transfer of the capsules from a water storage pool to the air environment of an irradiator facility. This report covers results from tests that simulated the effects of the 90-min fire and from thermal cycling actual WESF cesium capsules for 3845 cycles over a period of six months. 11 refs., 39 figs., 9 tabs

High convergence, indirect drive inertial confinement fusion experiments at Nova

International Nuclear Information System (INIS)

Lerche, R.A.; Cable, M.D.; Hatchett, S.P.; Caird, J.A.; Kilkenny, J.D.; Kornblum, H.N.; Lane, S.M.; Laumann, C.; Murphy, T.J.; Murray, J.; Nelson, M.B.; Phillion, D.W.; Powell, H.; Ress, D.

1996-01-01

High convergence, indirect drive implosion experiments have been done at the Nova Laser Facility. The targets were deuterium and deuterium/tritium filled, glass microballoons driven symmetrically by x rays produced in a surrounding uranium hohlraum. Implosions achieved convergence ratios of 24:1 with fuel densities of 19 g/cm 3 ; this is equivalent to the range required for the hot spot of ignition scale capsules. The implosions used a shaped drive and were well characterized by a variety of laser and target measurements. The primary measurement was the fuel density using the secondary neutron technique (neutrons from the reaction 2 H( 3 H,n) 4 He in initially pure deuterium fuel). Laser measurements include power, energy and pointing. Simultaneous measurement of neutron yield, fusion reaction rate, and x-ray images provide additional information about the implosion process. Computer models are in good agreement with measurement results. copyright 1996 American Institute of Physics

Direct-indirect mixed implosion mode in heavy ion inertial fusion

International Nuclear Information System (INIS)

Kawata, S.; Miyazawa, K.; Kikuchi, T.; Someya, T.

2007-01-01

In order to realize an effective implosion, beam illumination non-uniformity on a fuel target must be suppressed less than a few percent. In this study, a direct-indirect mixture implosion mode is proposed and discussed in heavy ion beam (HIB) inertial confinement fusion (HIF) in order to release sufficient fusion energy in a robust manner. On the other hand, the HIB illumination non-uniformity depends strongly on a target displacement dz from the center of a fusion reactor chamber. In a direct-driven implosion mode, dz of ∼20 μm was tolerable, and in an indirect-implosion mode, dz of ∼100 μm was allowable. In the direct-indirect mixture mode target, a low-density foam layer is inserted, and the radiation energy is confined in the foam layer. In the foam layer, the radiation transport is expected to smooth the HIB illumination non-uniformity in the lateral direction. Two-dimensional implosion simulations are performed, and show that the HIB illumination non-uniformity is well smoothed in the direct-indirect mixture target. Our simulation results present that a large pellet displacement of approximately a few hundred microns is allowed in order to obtain a sufficient fusion energy output in HIF

Thinshell symmetry surrogates for the National Ignition Facility: A rocket equation analysis

Science.gov (United States)

Amendt, Peter; Shestakov, A. I.; Landen, O. L.; Bradley, D. K.; Pollaine, S. M.; Suter, L. J.; Turner, R. E.

2001-06-01

Several techniques for inferring the degree of flux symmetry in indirectly driven cylindrical hohlraums have been developed over the past several years for eventual application to the National Ignition Facility (NIF) [Paisner et al., Laser Focus World 30, 75 (1994)]. These methods use various ignition capsule surrogates, including non-cryogenic imploded capsules [Hauer et al., Phys. Plasmas 2, 2488 (1995)], backlit aerogel foamballs [Amendt et al., Rev. Sci. Instrum. 66, 785 (1995)], reemission balls [Delamater, Magelssen, and Hauer, Phys. Rev. E 53, 5240 (1996)], and backlit thinshells [Pollaine et al., Phys. Plasmas 8, 2357 (2001)]. Recent attention has focussed on the backlit thinshells as a promising means for detecting higher-order Legendre flux asymmetries, e.g., P6 and P8, which are predicted to be important sources of target performance degradation on the NIF for levels greater than 1% [Haan et al., Phys. Plasmas 2, 2490 (1995)]. A key property of backlit thinshells is the strong amplification of modal flux asymmetry imprinting with shell convergence. A simple single-parameter analytic description based on a rocket model is presented which explores the degree of linearity of the shell response to an imposed flux asymmetry. Convergence and mass ablation effects introduce a modest level of nonlinearity in the shell response. The effect of target fabrication irregularities on shell distortion is assessed with the rocket model and particular sensitivity to shell thickness variations is shown. The model can be used to relate an observed or simulated backlit implosion trajectory to an ablation pressure asymmetry history. Ascertaining this history is an important element for readily establishing the degree of surrogacy of a symmetry target for a NIF ignition capsule.

Thinshell symmetry surrogates for the National Ignition Facility: A rocket equation analysis

International Nuclear Information System (INIS)

Amendt, Peter; Shestakov, A.I.; Landen, O.L.; Bradley, D.K.; Pollaine, S.M.; Suter, L.J.; Turner, R.E.

2001-01-01

Several techniques for inferring the degree of flux symmetry in indirectly driven cylindrical hohlraums have been developed over the past several years for eventual application to the National Ignition Facility (NIF) [Paisner et al., Laser Focus World 30, 75 (1994)]. These methods use various ignition capsule surrogates, including non-cryogenic imploded capsules [Hauer et al., Phys. Plasmas 2, 2488 (1995)], backlit aerogel foamballs [Amendt et al., Rev. Sci. Instrum. 66, 785 (1995)], reemission balls [Delamater, Magelssen, and Hauer, Phys. Rev. E 53, 5240 (1996)], and backlit thinshells [Pollaine et al., Phys. Plasmas 8, 2357 (2001)]. Recent attention has focussed on the backlit thinshells as a promising means for detecting higher-order Legendre flux asymmetries, e.g., P6 and P8, which are predicted to be important sources of target performance degradation on the NIF for levels greater than 1% [Haan et al., Phys. Plasmas 2, 2490 (1995)]. A key property of backlit thinshells is the strong amplification of modal flux asymmetry imprinting with shell convergence. A simple single-parameter analytic description based on a rocket model is presented which explores the degree of linearity of the shell response to an imposed flux asymmetry. Convergence and mass ablation effects introduce a modest level of nonlinearity in the shell response. The effect of target fabrication irregularities on shell distortion is assessed with the rocket model and particular sensitivity to shell thickness variations is shown. The model can be used to relate an observed or simulated backlit implosion trajectory to an ablation pressure asymmetry history. Ascertaining this history is an important element for readily establishing the degree of surrogacy of a symmetry target for a NIF ignition capsule

Experimental Demonstration of X-Ray Drive Enhancement with Rugby-Shaped Hohlraums

Science.gov (United States)

Philippe, F.; Casner, A.; Caillaud, T.; Landoas, O.; Monteil, M. C.; Liberatore, S.; Park, H. S.; Amendt, P.; Robey, H.; Sorce, C.; Li, C. K.; Seguin, F.; Rosenberg, M.; Petrasso, R.; Glebov, V.; Stoeckl, C.

2010-01-01

Rugby-shaped hohlraums have been suggested as a way to enhance x-ray drive in the indirect drive approach to inertial confinement fusion. This Letter presents an experimental comparison of rugby-shaped and cylinder hohlraums used for D2 and DHe3-filled capsules implosions on the Omega laser facility, demonstrating an increase of x-ray flux by 18% in rugby-shaped hohlraums. The highest yields to date for deuterium gas implosions in indirect drive on Omega (1.5×1010 neutrons) were obtained, allowing for the first time the measurement of a DD burn history. Proton spectra measurements provide additional validation of the higher drive in rugby-shaped hohlraums.

Effects of seed magnetic fields on magnetohydrodynamic implosion structure and dynamics

KAUST Repository

Mostert, W.

2014-12-01

The effects of various seed magnetic fields on the dynamics of cylindrical and spherical implosions in ideal magnetohydrodynamics are investigated. Here, we present a fundamental investigation of this problem utilizing cylindrical and spherical Riemann problems under three seed field configurations to initialize the implosions. The resulting flows are simulated numerically, revealing rich flow structures, including multiple families of magnetohydrodynamic shocks and rarefactions that interact non-linearly. We fully characterize these flow structures, examine their axi- and spherisymmetry-breaking behaviour, and provide data on asymmetry evolution for different field strengths and driving pressures for each seed field configuration. We find that out of the configurations investigated, a seed field for which the implosion centre is a saddle point in at least one plane exhibits the least degree of asymmetry during implosion.

Effect of discrete wires on the implosion dynamics of wire array Z pinches

International Nuclear Information System (INIS)

Lebedev, S. V.; Beg, F. N.; Bland, S. N.; Chittenden, J. P.; Dangor, A. E.; Haines, M. G.; Kwek, K. H.; Pikuz, S. A.; Shelkovenko, T. A.

2001-01-01

A phenomenological model of wire array Z-pinch implosions, based on the analysis of experimental data obtained on the mega-ampere generator for plasma implosion experiments (MAGPIE) generator [I. H. Mitchell , Rev. Sci. Instrum. 67, 1533 (1996)], is described. The data show that during the first ∼80% of the implosion the wire cores remain stationary in their initial positions, while the coronal plasma is continuously jetting from the wire cores to the array axis. This phase ends by the formation of gaps in the wire cores, which occurs due to the nonuniformity of the ablation rate along the wires. The final phase of the implosion starting at this time occurs as a rapid snowplow-like implosion of the radially distributed precursor plasma, previously injected in the interior of the array. The density distribution of the precursor plasma, being peaked on the array axis, could be a key factor providing stability of the wire array implosions operating in the regime of discrete wires. The modified ''initial'' conditions for simulations of wire array Z-pinch implosions with one-dimension (1D) and two-dimensions (2D) in the r--z plane, radiation-magnetohydrodynamic (MHD) codes, and a possible scaling to a larger drive current are discussed

Instability study during implosion in the Tupa Theta-Pinch

International Nuclear Information System (INIS)

Kayama, M.E.; Boeckelmann, H.K.

1986-01-01

The importance of instabilities which occur during plasma heating in a Theta Pinch, in the implosion phase, is analysed. The plasma diagnostic was done by ultrafast photography and diamagnetic probe. The implosion time and the current layer thickness were calculated using a hybrid code for plasma simulation. The theoretical data were compared with the experimental ones. (M.C.K.) [pt

Progress in hohlraum physics for the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Moody, J. D., E-mail: moody4@llnl.gov; Callahan, D. A.; Hinkel, D. E.; Amendt, P. A.; Baker, K. L.; Bradley, D.; Celliers, P. M.; Dewald, E. L.; Divol, L.; Döppner, T.; Eder, D. C.; Edwards, M. J.; Jones, O.; Haan, S. W.; Ho, D.; Hopkins, L. B.; Izumi, N.; Kalantar, D.; Kauffman, R. L.; Kilkenny, J. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); and others

2014-05-15

Advances in hohlraums for inertial confinement fusion at the National Ignition Facility (NIF) were made this past year in hohlraum efficiency, dynamic shape control, and hot electron and x-ray preheat control. Recent experiments are exploring hohlraum behavior over a large landscape of parameters by changing the hohlraum shape, gas-fill, and laser pulse. Radiation hydrodynamic modeling, which uses measured backscatter, shows that gas-filled hohlraums utilize between 60% and 75% of the laser power to match the measured bang-time, whereas near-vacuum hohlraums utilize 98%. Experiments seem to be pointing to deficiencies in the hohlraum (instead of capsule) modeling to explain most of the inefficiency in gas-filled targets. Experiments have begun quantifying the Cross Beam Energy Transfer (CBET) rate at several points in time for hohlraum experiments that utilize CBET for implosion symmetry. These measurements will allow better control of the dynamic implosion symmetry for these targets. New techniques are being developed to measure the hot electron energy and energy spectra generated at both early and late time. Rugby hohlraums offer a target which requires little to no CBET and may be less vulnerable to undesirable dynamic symmetry “swings.” A method for detecting the effect of the energetic electrons on the fuel offers a direct measure of the hot electron effects as well as a means to test energetic electron mitigation methods. At higher hohlraum radiation temperatures (including near vacuum hohlraums), the increased hard x-rays (1.8–4 keV) may pose an x-ray preheat problem. Future experiments will explore controlling these x-rays with advanced wall materials.

Design of foam-buffered high gain target with Fokker-Planck implosion simulation for thermal insulation and imprint mitigation

International Nuclear Information System (INIS)

Takeda, T.; Mima, K.; Norimatsu, T.; Nagatomo, H.; Nishiguchi, A.

2003-01-01

It is proposed that a thick foam layer on a plastic capsule of fusion pellet is effective not only for reducing the initial imprint, but also for solving the melting problem of cryogenic deuterium-tritium layer, in a reactor chamber. Investigated are the dependences of gain, thermal insulation for preventing the melting, and imprint mitigation of a foam-buffered target on the foam layer thickness. The imprint mitigation, the Rayleigh-Taylor growth factor and the fusion gain of a foam-buffered target are evaluated by the hydrodynamic implosion code HIMICO [A. Nishiguchi et al., Phys. Fluids B 4, 417 (1992)], which includes a Fokker-Planck transport code. As the result, it is found that high gain can be achieved by the foam-buffered target together with thermal insulation and imprint mitigation

Dynamic hohlraum and ICF pellet implosion experiments on Z

International Nuclear Information System (INIS)

Nash, T.J.; Derzon, M.S.; Chandler, G.A.

1999-01-01

By stabilizing an imploding z-pinch on Z (20 MA, 100 ns) with a solid current return can and a nested wire array the authors have achieved dynamic hohlraum radiation temperatures over 200 eV at a diameter of approximately 1 mm. The pinch configuration yielding this temperature is a nested tungsten wire array of 240 and 120 wires at 4 and 2 cm diameters weighing 2 and 1 mg, 1 cm long, imploding onto a 5 mm diameter, 14 mg/cc cylindrical CH foam, weighing 3 mg. They have used a single 4 cm diameter tungsten wire array to drive a 1.6 mm diameter ICF capsule mounted in a 6 mg/cc foam inside a 3 mg copper annulus at 5 mm diameter, and measured x-ray emissions indicative of the pellet implosion. Mounting the pellet in foam may have caused the hohlraum to become equator-hot. They will present results from upcoming pellet experiments in which the pellet is mounted by thread and driven by a larger diameter, 6 or 7 mm, copper annulus to improve radiation drive symmetry. They will also discuss designs for tapered foam annular targets that distort a cylindrical pinch into a quasi-sphere that will wrap around an ICF pellet to further improve drive symmetry

Work plan for testing silicone impression material and fixture on pool cell capsule

International Nuclear Information System (INIS)

Lundeen, J.E.

1994-01-01

The purpose of this work plan is to provide a safe procedure to test a cesium capsule impression fixture at Waste Encapsulation and Storage Facility (WESF). The impression will be taken with silicone dental impression material pressed down upon the capsule using the impression fixture. This test will evaluate the performance of the fixture and impression material under high radiation and temperature conditions on a capsule in a WESF pool cell

Modeling, measuring, and mitigating instability growth in liner implosions on Z

Science.gov (United States)

Peterson, Kyle

2015-11-01

Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. In this talk, we will discuss the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. We present simulations that show electro-thermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent magneto-Rayleigh-Taylor (MRT) instability growth. We discuss measurement results from experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electro-thermal instability growth on well-characterized initially solid aluminum or beryllium rods driven with a 20 MA, 100 ns risetime current pulse. These measurements show good agreement with electro-thermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone. Recent experiments have confirmed simulation predictions of dramatically reduced instability growth in solid metallic rods when thick dielectric coatings are used to mitigate density perturbations arising from the electro-thermal instability. These results provide further evidence that the inherent surface roughness of the target is not the dominant seed for the MRT instability, in contrast with most inertial confinement fusion approaches. These results suggest a new technique for substantially reducing the integral MRT growth in magnetically driven implosions. Indeed, recent results on the Z facility with 100 km/s Al and Be liner implosions show substantially reduced growth. These new results include axially magnetized, CH-coated beryllium liner radiographs in which the inner liner surface is observed to be remarkably straight and uniform at a radius of about 120 microns (convergence ratio ~20). Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under

Shock ignition of high gain inertial fusion capsules

International Nuclear Information System (INIS)

Schurtz, G.; Ribeyre, X.; Lebel, E.; Casner, A.

2010-01-01

the theoretical approach of SI, and Lafon et al. established its gain curves using an extension of the Rosen Lindl model. The efficiency of shock ignition comes from the fact that, unlike conventional central ignition, the final fuel assembly is not isobaric, i.e., the low density hot spot pressure significantly exceeds the pressure of the surrounding cold dense fuel. This high hot spot pressure is obtained from two pressure amplification stages: the first amplification mechanism is spherical convergence. A converging shock increases its strength as C 0.9 where C is the shock convergence ratio. A second amplification stage occurs when the ignition shock collides with the outward directed shock that results from the shell stagnation at target centre. Under optimal matching conditions, shock collision produces a x 6 amplification of pressure. We discuss in the presentation the conditions for the obtention of optimal pressure amplification, at first by studying the ignition window in the space spanned by laser power and launching time, and secondly by modelling the relation ship between the laser intensity required for shock production and the implosion velocity. This latter study indicates a sensible safety trade off using a 250 km/s implosion velocity and a laser spike of ∼ 5 x 10 15 W/cm 2 for the shock production. First kinetic calculations and implosion experiments indicate that laser plasma interaction in the regime of shock ignition may remain under control, provided that the SRS generated hot electrons energy stay below 80 keV. Shock Ignition has been proposed as the baseline of the HiPER project and shock ignition experiments have been proposed on the National Ignition Facility with gains expected between 60 and 100 at laser energies below 500 kJ. Acknowledgments. This work is partly supported by the Aquitaine Region Council.

Understanding Yield Anomalies in ICF Implosions via Fully Kinetic Simulations

Science.gov (United States)

Taitano, William

2017-10-01

In the quest towards ICF ignition, plasma kinetic effects are among prime candidates for explaining some significant discrepancies between experimental observations and rad-hydro simulations. To assess their importance, high-fidelity fully kinetic simulations of ICF capsule implosions are needed. Owing to the extremely multi-scale nature of the problem, kinetic codes have to overcome nontrivial numerical and algorithmic challenges, and very few options are currently available. Here, we present resolutions of some long-standing yield discrepancy conundrums using a novel, LANL-developed, 1D-2V Vlasov-Fokker-Planck code iFP. iFP possesses an unprecedented fidelity and features fully implicit time-stepping, exact mass, momentum, and energy conservation, and optimal grid adaptation in phase space, all of which are critically important for ensuring long-time numerical accuracy of the implosion simulations. Specifically, we concentrate on several anomalous yield degradation instances observed in Omega campaigns, with the so-called ``Rygg effect'', or an anomalous yield scaling with the fuel composition, being a prime example. Understanding the physical mechanisms responsible for such degradations in non-ignition-grade Omega experiments is of great interest, as such experiments are often used for platform and diagnostic development, which are then used in ignition-grade experiments on NIF. In the case of Rygg's experiments, effects of a kinetic stratification of fuel ions on the yield have been previously proposed as the anomaly explanation, studied with a kinetic code FPION, and found unimportant. We have revisited this issue with iFP and obtained excellent yield-over-clean agreement with the original Rygg results, and several subsequent experiments. This validates iFP and confirms that the kinetic fuel stratification is indeed at the root of the observed yield degradation. This work was sponsored by the Metropolis Postdoctoral Fellowship, LDRD office, Thermonuclear Burn

Rugby-like hohlraum experimental designs for demonstrating x-ray drive enhancement

Science.gov (United States)

Amendt, Peter; Cerjan, C.; Hinkel, D. E.; Milovich, J. L.; Park, H.-S.; Robey, H. F.

2008-01-01

A suite of experimental designs for the Omega laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)] using rugby and cylindrical hohlraums is proposed to confirm the energetics benefits of rugby-shaped hohlraums over cylinders under optimal implosion symmetry conditions. Postprocessed Dante x-ray drive measurements predict a 12-17eV (23%-36%) peak hohlraum temperature (x-ray flux) enhancement for a 1ns flattop laser drive history. Simulated core self-emission x-ray histories also show earlier implosion times by 200-400ps, depending on the hohlraum case-to-capsule ratio and laser-entrance-hole size. Capsules filled with 10 or 50atm of deuterium (DD) are predicted to give in excess of 1010 neutrons in two-dimensional hohlraum simulations in the absence of mix, enabling DD burn history measurements for the first time in indirect-drive on Omega. Capsule designs with 50atm of DHe3 are also proposed to make use of proton slowing for independently verifying the drive benefits of rugby hohlraums. Scale-5/4 hohlraum designs are also introduced to provide further margin to potential laser-plasma-induced backscatter and hot-electron production.

Rugby-like hohlraum experimental designs for demonstrating x-ray drive enhancement

International Nuclear Information System (INIS)

Amendt, Peter; Cerjan, C.; Hinkel, D. E.; Milovich, J. L.; Park, H.-S.; Robey, H. F.

2008-01-01

A suite of experimental designs for the Omega laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)] using rugby and cylindrical hohlraums is proposed to confirm the energetics benefits of rugby-shaped hohlraums over cylinders under optimal implosion symmetry conditions. Postprocessed Dante x-ray drive measurements predict a 12-17 eV (23%-36%) peak hohlraum temperature (x-ray flux) enhancement for a 1 ns flattop laser drive history. Simulated core self-emission x-ray histories also show earlier implosion times by 200-400 ps, depending on the hohlraum case-to-capsule ratio and laser-entrance-hole size. Capsules filled with 10 or 50 atm of deuterium (DD) are predicted to give in excess of 10 10 neutrons in two-dimensional hohlraum simulations in the absence of mix, enabling DD burn history measurements for the first time in indirect-drive on Omega. Capsule designs with 50 atm of D 3 He are also proposed to make use of proton slowing for independently verifying the drive benefits of rugby hohlraums. Scale-5/4 hohlraum designs are also introduced to provide further margin to potential laser-plasma-induced backscatter and hot-electron production

Crossed-swords, capsule-pinch technique for capsulotomy in pediatric and/or loose lens cataract extraction.

Science.gov (United States)

Snyder, Michael E; Lindsell, Luke B

2010-02-01

Puncturing the anterior capsule in a patient with a very soft lens, an elastic capsule, and/or deficient zonular countertraction can be challenging even with a sharp needle or blade. The crossed-swords, capsule-pinch technique capitalizes on opposing forces from 2 needles directed toward each other with a "pinch" of the capsule between their tips. This affords a controlled and facile puncture of the capsule without creating stress on the zonules or anteroposterior displacement of the lens. Copyright 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Boundary Layer Transition and Trip Effectiveness on an Apollo Capsule in the JAXA High Enthalpy Shock Tunnel (HIEST) Facility

Science.gov (United States)

Kirk, Lindsay C.; Lillard, Randolph P.; Olejniczak, Joseph; Tanno, Hideyuki

2015-01-01

Computational assessments were performed to size boundary layer trips for a scaled Apollo capsule model in the High Enthalpy Shock Tunnel (HIEST) facility at the JAXA Kakuda Space Center in Japan. For stagnation conditions between 2 MJ/kg and 20 MJ/kg and between 10 MPa and 60 MPa, the appropriate trips were determined to be between 0.2 mm and 1.3 mm high, which provided kappa/delta values on the heatshield from 0.15 to 2.25. The tripped configuration consisted of an insert with a series of diamond shaped trips along the heatshield downstream of the stagnation point. Surface heat flux measurements were obtained on a capsule with a 250 mm diameter, 6.4% scale model, and pressure measurements were taken at axial stations along the nozzle walls. At low enthalpy conditions, the computational predictions agree favorably to the test data along the heatshield centerline. However, agreement becomes less favorable as the enthalpy increases conditions. The measured surface heat flux on the heatshield from the HIEST facility was under-predicted by the computations in these cases. Both smooth and tripped configurations were tested for comparison, and a post-test computational analysis showed that kappa/delta values based on the as-measured stagnation conditions ranged between 0.5 and 1.2. Tripped configurations for both 0.6 mm and 0.8 mm trip heights were able to effectively trip the flow to fully turbulent for a range of freestream conditions.

Plasma dynamics in aluminium wire array Z-pinch implosions

International Nuclear Information System (INIS)

Bland, S.N.

2001-01-01

The wire array Z-pinch is the world's most powerful laboratory X-ray source. An achieved power of ∼280TW has generated great interest in the use of these devices as a source of hohlraum heating for inertial confinement fusion experiments. However, the physics underlying how wire array Z-pinches implode is not well understood. This thesis presents the first detailed measurements of plasma dynamics in wire array experiments. The MAGPIE generator, with currents of up to 1.4MA, 150ns 10-90% rise-time, was used to implode arrays of 16mm diameter typically containing between 8 and 64 15μm aluminium wires. Diagnostics included: end and side-on laser probing with interferometry, schlieren and shadowgraphy channels; radial and axial streak photography; gated X-ray imaging; XUV and hard X-ray spectrometry; filtered XRDs and diamond PCDs; and a novel X-ray backlighting system to probe high density plasma. It was found that the plasma formed from the wires consisted of cold, dense cores, which ablated producing hot, low density coronal plasma. After an initial acceleration around the cores, coronal plasma streams flowed force-free towards the axis, with an instability wavelength determined by the core size. At ∼50% of the implosion time, the streams collided on axis forming a precursor plasma which appeared to be uniform, stable, and inertially confined. The existence of core-corona structure significantly affected implosion dynamics. For arrays with <64 wires, the wire cores remained in their original positions until ∼80% of the implosion time before accelerating rapidly. At 64 wires a transition in implosion trajectories to 0-D like occurred indicating a possible merger of current carrying plasma close to the cores - the cores themselves did not merge. During implosion, the cores initially developed uncorrelated instabilities that then transformed into a longer wavelength global mode of instability. The study of nested arrays (2 concentric arrays, one inside the other

Implosion anisotropy of neutron kinetic energy distributions as measured with the neutron time-of-flight diagnostics at the National Ignition Facility

Science.gov (United States)

Hartouni, Edward; Eckart, Mark; Field, John; Grim, Gary; Hatarik, Robert; Moore, Alastair; Munro, David; Sayer, Daniel; Schlossberg, David

2017-10-01

Neutron kinetic energy distributions from fusion reactions are characterized predominantly by the excess energy, Q, of the fusion reaction and the variance of kinetic energy which is related to the thermal temperature of the plasma as shown by e.g. Brysk. High statistics, high quality neutron time-of-flight spectra obtained at the National Ignition Facility provide a means of measuring small changes to the neutron kinetic energy due to the spatial and temporal distribution of plasma temperature, density and velocity. The modifications to the neutron kinetic energy distribution as described by Munro include plasma velocity terms with spatial orientation, suggesting that the neutron kinetic energy distributions could be anisotropic when viewed by multiple lines-of-sight. These anisotropies provide a diagnostic of burn averaged plasma velocity distributions. We present the results of measurements made for a variety of DT implosions and discuss their possible physical interpretations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC.

Simultaneous diagnosis of radial profiles and mix in NIF ignition-scale implosions via X-ray spectroscopy

Science.gov (United States)

Ciricosta, O.; Scott, H.; Durey, P.; Hammel, B. A.; Epstein, R.; Preston, T. R.; Regan, S. P.; Vinko, S. M.; Woolsey, N. C.; Wark, J. S.

2017-11-01

In a National Ignition Facility implosion, hydrodynamic instabilities may cause the cold material from the imploding shell to be injected into the hot-spot (hot-spot mix), enhancing the radiative and conductive losses, which in turn may lead to a quenching of the ignition process. The bound-bound features of the spectrum emitted by high-Z ablator dopants that get mixed into the hot-spot have been previously used to infer the total amount of mixed mass; however, the typical errorbars are larger than the maximum tolerable mix. We present here an improved 2D model for mix spectroscopy which can be used to retrieve information on both the amount of mixed mass and the full imploded plasma profile. By performing radiation transfer and simultaneously fitting all of the features exhibited by the spectra, we are able to constrain self-consistently the effect of the opacity of the external layers of the target on the emission, thus improving the accuracy of the inferred mixed mass. The model's predictive capabilities are first validated by fitting simulated spectra arising from fully characterized hydrodynamic simulations, and then, the model is applied to previously published experimental results, providing values of mix mass in agreement with previous estimates. We show that the new self consistent procedure leads to better constrained estimates of mix and also provides insight into the sensitivity of the hot-spot spectroscopy to the spatial properties of the imploded capsule, such as the in-flight aspect ratio of the cold fuel surrounding the hotspot.

Preparing for polar-drive ignition on the National Ignition Facility

Directory of Open Access Journals (Sweden)

McKenty P.W.

2013-11-01

Full Text Available The implementation of polar drive (PD at the National Ignition Facility (NIF will enable the execution of direct-drive implosions while the facility is configured for x-ray drive. The Laboratory for Laser Energetics (LLE, in collaboration with LLNL, LANL and GA, is implementing PD on the NIF. LLE has designed and participates in the use of PD implosions for diagnostic commissioning on the NIF. LLE has an active experimental campaign to develop PD in both warm and cryogenic target experiments on OMEGA. LLE and its partners are developing a Polar Drive Project Execution Plan, which will provide a detailed outline of the requirements, resources, and timetable leading to PD-ignition experiments on the NIF.

Self-similar analysis of the spherical implosion process

International Nuclear Information System (INIS)

Ishiguro, Yukio; Katsuragi, Satoru.

1976-07-01

The implosion processes caused by laser-heating ablation has been studied by self-similarity analysis. Attention is paid to the possibility of existence of the self-similar solution which reproduces the implosion process of high compression. Details of the self-similar analysis are reproduced and conclusions are drawn quantitatively on the gas compression by a single shock. The compression process by a sequence of shocks is discussed in self-similarity. The gas motion followed by a homogeneous isentropic compression is represented by a self-similar motion. (auth.)

Recent progress of an integrated implosion code and modeling of element physics

International Nuclear Information System (INIS)

Nagatomo, H.; Takabe, H.; Mima, K.; Ohnishi, N.; Sunahara, A.; Takeda, T.; Nishihara, K.; Nishiguchu, A.; Sawada, K.

2001-01-01

Physics of the inertial fusion is based on a variety of elements such as compressible hydrodynamics, radiation transport, non-ideal equation of state, non-LTE atomic process, and relativistic laser plasma interaction. In addition, implosion process is not in stationary state and fluid dynamics, energy transport and instabilities should be solved simultaneously. In order to study such complex physics, an integrated implosion code including all physics important in the implosion process should be developed. The details of physics elements should be studied and the resultant numerical modeling should be installed in the integrated code so that the implosion can be simulated with available computer within realistic CPU time. Therefore, this task can be basically separated into two parts. One is to integrate all physics elements into a code, which is strongly related to the development of hydrodynamic equation solver. We have developed 2-D integrated implosion code which solves mass, momentum, electron energy, ion energy, equation of states, laser ray-trace, laser absorption radiation, surface tracing and so on. The reasonable results in simulating Rayleigh-Taylor instability and cylindrical implosion are obtained using this code. The other is code development on each element physics and verification of these codes. We had progress in developing a nonlocal electron transport code and 2 and 3 dimension radiation hydrodynamic code. (author)

Diagnostic for determining the mix in inertial confinement fusion capsule hotspot

Energy Technology Data Exchange (ETDEWEB)

He, Shibei; Ding, Yongkun, E-mail: ding-yk@vip.sina.com; Miao, Wenyong; Zhang, Xing; Tu, Shaoyong; Yuan, Yongteng; Pu, Yudong; Yan, Ji; Wei, Minxi; Yin, Chuansheng [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

2016-07-15

A diagnostic is developed for determining the hotspot mix in inertial confinement fusion experiments. A multi-channel pinhole camera measures Bremsstrahlung emissions from implosion capsules ranging from 6 keV to 30 keV and records an image of the hotspot. Meanwhile, a planar crystal spectrometer measures Ar line emissions used to deduce the electron density of the hotspot. An X-ray streaked camera records the burn duration. With the Bremsstrahlung spectrum, electron density, hotspot volume, and burn duration, the mix quantity is determined by solving a pair of linear equations. This inferred mix amount has an uncertainty due to the uncertainty of the electron density, but with the help of the measured neutron product, the most likely mix quantity value can be determined. This technique is applied to experimental images to infer the quantity of CH ablator mix into the hotspot.

Diagnostic for determining the mix in inertial confinement fusion capsule hotspot

International Nuclear Information System (INIS)

He, Shibei; Ding, Yongkun; Miao, Wenyong; Zhang, Xing; Tu, Shaoyong; Yuan, Yongteng; Pu, Yudong; Yan, Ji; Wei, Minxi; Yin, Chuansheng

2016-01-01

A diagnostic is developed for determining the hotspot mix in inertial confinement fusion experiments. A multi-channel pinhole camera measures Bremsstrahlung emissions from implosion capsules ranging from 6 keV to 30 keV and records an image of the hotspot. Meanwhile, a planar crystal spectrometer measures Ar line emissions used to deduce the electron density of the hotspot. An X-ray streaked camera records the burn duration. With the Bremsstrahlung spectrum, electron density, hotspot volume, and burn duration, the mix quantity is determined by solving a pair of linear equations. This inferred mix amount has an uncertainty due to the uncertainty of the electron density, but with the help of the measured neutron product, the most likely mix quantity value can be determined. This technique is applied to experimental images to infer the quantity of CH ablator mix into the hotspot.

Laser driven implosion of gas filled microballoons

International Nuclear Information System (INIS)

Key, M.H.; Evans, R.G.; Nicholas, D.J.

1978-01-01

The characteristics of the exploding pusher compression process have been studied experimentally and by computer modelling. Time and space resolved imaging and spectroscopy of X-ray emission has been used to determine the plasma parameters in both the outer corona and the implosion core. Neutron yield has been applied as an ion temperature indicator. The data thus obtained are related to 1D computer modelling with emphasis on the role of hot electron energy transport. Physical processes in the plasma corona have been investigated through observations of fast ions, hard X-rays and harmonic generation. Diagnostic methods for dense implosion plasma will be discussed. (author)

Symmetry and illumination uniformity requirements for high density laser-driven implosions

International Nuclear Information System (INIS)

Mead, W.C.; Lindl, J.D.

1976-01-01

As laser capabilities increase, implosions will be performed to achieve high densities. Criteria are discussed for formation of a low-density corona, preheated supersonically, which increases the tolerance of high convergence implosions to non-uniform illumination by utilizing thermal smoothing. We compare optimized double shell target designs without and with atmosphere production. Two significant penalties are incurred with atmosphere production using 1 μm laser light. First, a large initial shock at the ablation surface limits the pulse shaping flexibility, and degrades implosion performance. Second, the mass and heat capacity of the atmosphere reduce the energy delivered to the ablation surface and the driving pressures obtained for a given input energy. Improvement is possible using 2 μm light for the initial phase of the implosion. We present results of 2-D simulations which evaluate combined symmetry and stability requirements. At l = 8, the improvement produced in the example is a factor of 10, giving tolerance of 10 percent

Enthalpy generation from mixing in hohlraum-driven targets

Science.gov (United States)

Amendt, Peter; Milovich, Jose

2016-10-01

The increase in enthalpy from the physical mixing of two initially separated materials is analytically estimated and applied to ICF implosions and gas-filled hohlraums. Pressure and temperature gradients across a classical interface are shown to be the origin of enthalpy generation from mixing. The amount of enthalpy generation is estimated to be on the order of 100 Joules for a 10 micron-scale annular mixing layer between the solid deuterium-tritium fuel and the undoped high-density carbon ablator of a NIF-scale implosion. A potential resonance is found between the mixing layer thickness and gravitational (Cs2/ g) and temperature-gradient scale lengths, leading to elevated enthalpy generation. These results suggest that if mixing occurs in current capsule designs for the National Ignition Facility, the ignition margin may be appreciably eroded by the associated enthalpy of mixing. The degree of enthalpy generation from mixing of high- Z hohlraum wall material and low- Z gas fills is estimated to be on the order of 100 kJ or more for recent NIF-scale hohlraum experiments, which is consistent with the inferred missing energy based on observed delays in capsule implosion times. Work performed under the auspices of Lawrence Livermore National Security, LLC (LLNS) under Contract No. DE-AC52-07NA27344.

Analysis and radiation dose rate measurement of the Al-1050 capsule on the rabbit system facility

International Nuclear Information System (INIS)

Sarwani; Sutrisno; H, Saleh; Rohidi; M, Kawkab

2000-01-01

Aluminium is a kind of light metal with density of 2.7 gram /cm exp 3,regarding to the aluminium is characteristic such as easy to fabricated,has a good corrosion resistant and radiation heat resistant, therefore aluminum is selected to be used as a material for sample irradiation capsule with high neutron fluency. Analysis using neutron activation method and capsule irradiation by using high neutron fluency and dose radiation rate measurement was done. The analysis result show that impurities in the Al-1050 capsule are Fe, Cu, Mg, Sb, Zn, and Mn. The capsule irradiated at 15 MW during 6 Hours with neutron fluency of 2,8 x 10 exp 17 n/cm exp 2. The radiation doses rate after 24 hours decay is 220 mrad/h at 0-meter distance and 60 mrad/h at 1-meter distance. Respectively. From the analysis results and measurement show that the Al-1050 capsule has no high neutron absorption element and available to get continuing irradiation at 15 MW as far as 6 hours. Due to the personal safety, therefore the capsule handling could be carried out in the hot cell

Experimental Demonstration of X-Ray Drive Enhancement with Rugby-Shaped Hohlraums

International Nuclear Information System (INIS)

Philippe, F.; Casner, A.; Caillaud, T.; Landoas, O.; Monteil, M. C.; Liberatore, S.; Park, H. S.; Amendt, P.; Robey, H.; Sorce, C.; Li, C. K.; Seguin, F.; Rosenberg, M.; Petrasso, R.; Glebov, V.; Stoeckl, C.

2010-01-01

Rugby-shaped hohlraums have been suggested as a way to enhance x-ray drive in the indirect drive approach to inertial confinement fusion. This Letter presents an experimental comparison of rugby-shaped and cylinder hohlraums used for D 2 and D 3 He-filled capsules implosions on the Omega laser facility, demonstrating an increase of x-ray flux by 18% in rugby-shaped hohlraums. The highest yields to date for deuterium gas implosions in indirect drive on Omega (1.5x10 10 neutrons) were obtained, allowing for the first time the measurement of a DD burn history. Proton spectra measurements provide additional validation of the higher drive in rugby-shaped hohlraums.

Unambiguous Evidence of Coronal Implosions during Solar Eruptions and Flares

Science.gov (United States)

Wang, Juntao; Simões, P. J. A.; Fletcher, L.

2018-05-01

In the implosion conjecture, coronal loops contract as the result of magnetic energy release in solar eruptions and flares. However, after almost two decades, observations of this phenomenon are still rare and most previous reports are plagued by projection effects so that loop contraction could be either true implosion or just a change in loop inclination. In this paper, to demonstrate the reality of loop contractions in the global coronal dynamics, we present four events with the continuously contracting loops in an almost edge-on geometry from the perspective of SDO/AIA, which are free from the ambiguity caused by the projection effects, also supplemented by contemporary observations from STEREO for examination. In the wider context of observations, simulations and theories, we argue that the implosion conjecture is valid in interpreting these events. Furthermore, distinct properties of the events allow us to identify two physical categories of implosion. One type demonstrates a rapid contraction at the beginning of the flare impulsive phase, as magnetic free energy is removed rapidly by a filament eruption. The other type, which has no visible eruption, shows a continuous loop shrinkage during the entire flare impulsive phase, which we suggest shows the ongoing conversion of magnetic free energy in a coronal volume. Corresponding scenarios are described that can provide reasonable explanations for the observations. We also point out that implosions may be suppressed in cases when a heavily mass-loaded filament is involved, possibly serving as an alternative account for their observational rarity.

Phenomenological modeling of argon Z-pinch implosions

International Nuclear Information System (INIS)

Whitney, K.G.; Thornhill, J.W.; Deeney, C.; LePell, P.D.; Coulter, M.C.

1992-01-01

The authors investigate some of the effects of plasma turbulence on the K-shell emission dynamics of argon gas puff Z-pinch implosions. The increases that turbulence produces in the plasma viscosity, heat conductivity, and electrical resistivity are modeled phenomenologically using multipliers for these quantities in the MHD calculations. The choice of multipliers was made by benchmarking a 1-D MHD simulation of a Physics International Inc. argon gas puff experiment against the inferred densities and temperatures achieved in the experiment. These multipliers were then used to study the parametric dependence of the K-shell emission on the energy input to the argon plasma for a fixed mass loading. Comparisons between turbulent and non-turbulent argon implosions are made

Nuclear Diagnostics at the National Ignition Facility, 2013-2015

Science.gov (United States)

Yeamans, C. B.; Cassata, W. S.; Church, J. A.; Fittinghoff, D. N.; Gatu Johnson, M.; Gharibyan, N.; Határik, R.; Sayre, D. B.; Sio, H. W.; Bionta, R. M.; Bleuel, D. L.; Caggiano, J. A.; Cerjan, C. J.; Cooper, G. W.; Eckart, M. J.; Edwards, E. R.; Faye, S. A.; Forrest, C. J.; Frenje, J. A.; Glebov, V. Yu; Grant, P. M.; Grim, G. P.; Hartouni, E. P.; Herrmann, H. W.; Kilkenny, J. D.; Knauer, J. P.; Mackinnon, A. J.; Merrill, F. E.; Moody, K. J.; Moran, M. J.; Petrasso, R. D.; Phillips, T. W.; Rinderknecht, H. G.; Schneider, D. H. G.; Sepke, S. M.; Shaughnessy, D. A.; Stoeffl, W.; Velsko, C. A.; Volegov, P.

2016-05-01

The National Ignition Facility (NIF) relies on a suite of nuclear diagnostics to measure the neutronic output of experiments. Neutron time-of-flight (NTOF) and neutron activation diagnostics (NAD) provide performance metrics of absolute neutron yield and neutron spectral content: spectral width and non-thermal content, from which implosion physical quantities of temperature and scattering mass are inferred. Spatially-distributed flange- mounted NADs (FNAD) measure, with nearly identical systematic uncertainties, primary DT neutron emission to infer a whole-sky neutron field. An automated FNAD system is being developed. A magnetic recoil spectrometer (MRS) shares few systematics with comparable NTOF and NAD devices, and as such is deployed for independent measurement of the primary neutronic quantities. The gas-Cherenkov Gamma Reaction History (GRH) instrument records four energy channels of time-resolved gamma emission to measure nuclear bang time and burn width, as well as to infer carbon areal density in experiments utilizing plastic or diamond capsules. A neutron imaging system (NIS) takes two images of the neutron source, typically gated to create coregistered 13-15 MeV primary and 6-12 MeV downscattered images. The radiochemical analysis of gaseous samples (RAGS) instrument pumps target chamber gas to a chemical reaction and fractionation system configured with gamma counters, allowing measurement of radionuclides with half-lives as short as 8 seconds. Solid radiochemistry collectors (SRC) with backing NAD foils collect target debris, where activated materials from the target assembly are used as indicators of neutron spectrum content, and also serve as the primary diagnostic for nuclear forensic science experiments. Particle time-of-flight (PTOF) measures compression-bang time using DT- or DD-neutrons, as well as shock bang-time using D3He-protons for implosions with lower x-ray background. In concert, these diagnostics serve to measure the basic and advanced

Mix and hydrodynamic instabilities on NIF

Science.gov (United States)

Smalyuk, V. A.; Robey, H. F.; Casey, D. T.; Clark, D. S.; Döppner, T.; Haan, S. W.; Hammel, B. A.; MacPhee, A. G.; Martinez, D.; Milovich, J. L.; Peterson, J. L.; Pickworth, L.; Pino, J. E.; Raman, K.; Tipton, R.; Weber, C. R.; Baker, K. L.; Bachmann, B.; Berzak Hopkins, L. F.; Bond, E.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C.; Dixit, S. N.; Edwards, M. J.; Felker, S.; Field, J. E.; Fittinghoff, D. N.; Gharibyan, N.; Grim, G. P.; Hamza, A. V.; Hatarik, R.; Hohenberger, M.; Hsing, W. W.; Hurricane, O. A.; Jancaitis, K. S.; Jones, O. S.; Khan, S.; Kroll, J. J.; Lafortune, K. N.; Landen, O. L.; Ma, T.; MacGowan, B. J.; Masse, L.; Moore, A. S.; Nagel, S. R.; Nikroo, A.; Pak, A.; Patel, P. K.; Remington, B. A.; Sayre, D. B.; Spears, B. K.; Stadermann, M.; Tommasini, R.; Widmayer, C. C.; Yeamans, C. B.; Crippen, J.; Farrell, M.; Giraldez, E.; Rice, N.; Wilde, C. H.; Volegov, P. L.; Gatu Johnson, M.

2017-06-01

Several new platforms have been developed to experimentally measure hydrodynamic instabilities in all phases of indirect-drive, inertial confinement fusion implosions on National Ignition Facility. At the ablation front, instability growth of pre-imposed modulations was measured with a face-on, x-ray radiography platform in the linear regime using the Hydrodynamic Growth Radiography (HGR) platform. Modulation growth of "native roughness" modulations and engineering features (fill tubes and capsule support membranes) were measured in conditions relevant to layered DT implosions. A new experimental platform was developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, several experimental platforms were developed to measure both low-mode asymmetries and high-mode perturbations near peak compression with x-ray and nuclear techniques. In one innovative technique, the self-emission from the hot spot was enhanced with argon dopant to "self-backlight" the shell in-flight. To stabilize instability growth, new "adiabat-shaping" techniques were developed using the HGR platform and applied in layered DT implosions.

Capsule Development and Utilization for Material Irradiation Tests

International Nuclear Information System (INIS)

Kang, Young Hwan; Kim, B. G.; Joo, K. N.

2003-05-01

The objective of this project was to establish basic capsule irradiation technology using the multi-purpose research reactor [HANARO] to eventually support national R and D projects of advanced fuel and materials related to domestic nuclear power plants and next generation reactors. There are several national nuclear projects in KAERI, which require several irradiation tests to investigate in-pile behavior of nuclear reactor fuel and materials for the R and D of several types of fuels such as advanced PWR and DUPIC fuels and for the R and D of structural materials such as RPV(reactor pressure vessel) steel, Inconel, zirconium alloy, and stainless steel. At the moment, internal and external researchers in institutes, industries and universities are interested in investigating the irradiation characteristics of materials using the irradiation facilities of HANARO. For these kinds of material irradiation tests, it is important to develop various capsules using our own techniques. The development of capsules requires several leading-edge technologies and our own experiences related to design and fabrication. In the second phase from April 1,2000 to March 31, 2003, the utilization technologies were developed using various sensors for the measurements of temperature, pressure and displacement, and instrumented capsule technologies for the required fuel irradiation tests were developed. In addition, the improvement of the existing capsule technologies and the development of an in-situ measurable creep capsule for specific purposes were done to meet the various requirements of users

Current delivery and radiation yield in plasma flow switch-driven implosions

International Nuclear Information System (INIS)

Baker, W.L.; Degnan, J.H.; Beason, J.D.

1995-01-01

Vacuum inductive-store, plasma flow switch-driven implosion experiments have been performed using the Shiva Star capacitor bank (1300 μf, 3 nH, 120 kV, 9.4 MJ). A coaxial plasma gun arrangement is employed to store magnetic energy in the vacuum volume upstream of a dynamic discharge during the 3- to 4-μs rise of current from the capacitor bank. Motion of the discharge off the end of the inner conductor of the gun releases this energy to implode a coaxial cylindrical foil. The implosion loads are 5-cm-radius, 2-cm-long, 200 to 400 μg/cm 2 cylinders of aluminum or aluminized Formvar. With 5 MJ stored initially in the capacitor bank, more than 9 MA are delivered to the implosion load with a rise time of nearly 200 ns. The subsequent implosion results in a radiation output of 0.95 MJ at a power exceeding 5 TW (assuming isotropic emission). Experimental results and related two-dimensional magnetohydrodynamic simulations are discussed. 10 refs., 12 figs

Uniformity of spherical shock wave dynamically stabilized by two successive laser profiles in direct-drive inertial confinement fusion implosions

Energy Technology Data Exchange (ETDEWEB)

Temporal, M., E-mail: mauro.temporal@hotmail.com [Centre de Mathématiques et de Leurs Applications, ENS Cachan and CNRS, 61 Av. du President Wilson, F-94235 Cachan Cedex (France); Canaud, B. [CEA, DIF, F-91297 Arpajon Cedex (France); Garbett, W. J. [AWE plc, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Ramis, R. [ETSI Aeronáutica y del Espacio, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

2015-10-15

The implosion uniformity of a directly driven spherical inertial confinement fusion capsule is considered within the context of the Laser Mégajoule configuration. Two-dimensional (2D) hydrodynamic simulations have been performed assuming irradiation with two laser beam cones located at 49° and 131° with respect to the axis of symmetry. The laser energy deposition causes an inward shock wave whose surface is tracked in time, providing the time evolution of its non-uniformity. The illumination model has been used to optimize the laser intensity profiles used as input in the 2D hydro-calculations. It is found that a single stationary laser profile does not maintain a uniform shock front over time. To overcome this drawback, it is proposed to use two laser profiles acting successively in time, in order to dynamically stabilize the non-uniformity of the shock front.

Tritium handling facility at KMS Fusion Inc

International Nuclear Information System (INIS)

Bowman, C.C.; Vis, V.A.

1990-01-01

The tritium facility at KMS Fusion, Inc. supports the inertial confinement fusion research program. The main function of the facility is to fill glass and polymer Microshell (TM) capsules (small fuel containers) to a maximum pressure of 100 atm with tritium (T 2 ) or deuterium--tritium (DT). The recent upgrade of the facility allows us to fill Microshell capsules to a maximum pressure of 200 atm. A second fill port allows us to run long term fills of Macroshell (TM) capsules (large fuel containers) concurrently. The principle processes of the system are: (1) storage of the tritium as a uranium hydride; (2) pressure intensification using cryogenics; and (3) filling of the shells by permeation at elevated temperatures. The design of the facility was centered around a NRC license limit of 6000 Ci

Finite Atwood Number Effects on Deceleration-Phase Instability in Room-Temperature Direct-Drive Implosions

Science.gov (United States)

Miller, S.; Knauer, J. P.; Radha, P. B.; Goncharov, V. N.

2017-10-01

Performance degradation in direct-drive inertial confinement fusion implosions can be caused by several effects, one of which is Rayleigh-Taylor (RT) instability growth during the deceleration phase. In room-temperature plastic target implosions, this deceleration-phase RT growth is enhanced by the density discontinuity and finite Atwood numbers at the fuel-pusher interface. For the first time, an experimental campaign at the Omega Laser Facility systematically varied the ratio of deuterium-to-tritium (D-to-T) within the DT gas fill to change the Atwood number. The goal of the experiment was to understand the effects of Atwood number variation on observables like apparent ion temperature, yield, and variations in areal density and bulk fluid motion, which lead to broadening of neutron spectra along different lines of sight. Simulations by the hydrodynamic codes LILAC and DRACO were used to study growth rates for different D-to-T ratios and identify observable quantities effected by Atwood number variation. Results from simulations and the experiment are presented. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Ignition tuning for the National Ignition Campaign

Directory of Open Access Journals (Sweden)

Landen O.

2013-11-01

Full Text Available The overall goal of the indirect-drive inertial confinement fusion [1] tuning campaigns [2] is 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.

Effects of local defect growth in direct-drive cryogenic implosions on OMEGA

Energy Technology Data Exchange (ETDEWEB)

Igumenshchev, I. V.; Shmayda, W. T.; Harding, D. R.; Sangster, T. C. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Goncharov, V. N. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, Rochester, New York 14623 (United States); Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States); Department of Mechanical Engineering, University of Rochester, Rochester, New York 14623 (United States); Department of Physics and Astronomy, University of Rochester, Rochester, New York 14623 (United States)

2013-08-15

Spherically symmetric, low-adiabat (adiabat α ≲ 3) cryogenic direct-drive-implosion experiments on the OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1995)] yield less than 10% of the neutrons predicted in one-dimensional hydrodynamic simulations. Two-dimensional hydrodynamic simulations suggest that this performance degradation can be explained assuming perturbations from isolated defects of submicron to tens-of-micron scale on the outer surface or inside the shell of implosion targets. These defects develop during the cryogenic filling process and typically number from several tens up to hundreds for each target covering from about 0.2% to 1% of its surface. The simulations predict that such defects can significantly perturb the implosion and result in the injection of about 1 to 2 μg of the hot ablator (carbon-deuterium) and fuel (deuterium-tritium) materials from the ablation surface into the targets. Both the hot mass injection and perturbations of the shell reduce the final shell convergence ratio and implosion performance. The injected carbon ions radiatively cool the hot spot, reducing the fuel temperature, and further reducing the neutron yield. The negative effect of local defects can be minimized by decreasing the number and size of these defects and/or using more hydrodynamically stable implosion designs with higher shell adiabat.

The physics basis for ignition using indirect-drive targets on the National Ignition Facility

International Nuclear Information System (INIS)

Lindl, John D.; Amendt, Peter; Berger, Richard L.; Glendinning, S. Gail; Glenzer, Siegfried H.; Haan, Steven W.; Kauffman, Robert L.; Landen, Otto L.; Suter, Laurence J.

2004-01-01

The 1990 National Academy of Science final report of its review of the Inertial Confinement Fusion Program recommended completion of a series of target physics objectives on the 10-beam Nova laser at the Lawrence Livermore National Laboratory as the highest-priority prerequisite for proceeding with construction of an ignition-scale laser facility, now called the National Ignition Facility (NIF). These objectives were chosen to demonstrate that there was sufficient understanding of the physics of ignition targets that the laser requirements for laboratory ignition could be accurately specified. This research on Nova, as well as additional research on the Omega laser at the University of Rochester, is the subject of this review. The objectives of the U.S. indirect-drive target physics program have been to experimentally demonstrate and predictively model hohlraum characteristics, as well as capsule performance in targets that have been scaled in key physics variables from NIF targets. To address the hohlraum and hydrodynamic constraints on indirect-drive ignition, the target physics program was divided into the Hohlraum and Laser-Plasma Physics (HLP) program and the Hydrodynamically Equivalent Physics (HEP) program. The HLP program addresses laser-plasma coupling, x-ray generation and transport, and the development of energy-efficient hohlraums that provide the appropriate spectral, temporal, and spatial x-ray drive. The HEP experiments address the issues of hydrodynamic instability and mix, as well as the effects of flux asymmetry on capsules that are scaled as closely as possible to ignition capsules (hydrodynamic equivalence). The HEP program also addresses other capsule physics issues associated with ignition, such as energy gain and energy loss to the fuel during implosion in the absence of alpha-particle deposition. The results from the Nova and Omega experiments approach the NIF requirements for most of the important ignition capsule parameters, including

The experimental plan for cryogenic layered target implosions on the National Ignition Facility - The inertial confinement approach to fusion

International Nuclear Information System (INIS)

Edwards, M. J.; Lindl, J. D.; Spears, B. K.; Weber, S. V.; Atherton, L. J.; Bleuel, D. L.; Bradley, D. K.; Callahan, D. A.; Cerjan, C. J.; Clark, D; Collins, G. W.; Fair, J. E.; Fortner, R. J.; Glenzer, S. H.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Hatchett, S. P.; Izumi, N.; Jacoby, B.

2011-01-01

Ignition requires precisely controlled, high convergence implosions to assemble a dense shell of deuterium-tritium (DT) fuel with ρR>∼1 g/cm 2 surrounding a 10 keV hot spot with ρR ∼ 0.3 g/cm 2 . A working definition of ignition has been a yield of ∼1 MJ. At this yield the α-particle energy deposited in the fuel would have been ∼200 kJ, which is already ∼10 x more than the kinetic energy of a typical implosion. The National Ignition Campaign includes low yield implosions with dudded fuel layers to study and optimize the hydrodynamic assembly of the fuel in a diagnostics rich environment. The fuel is a mixture of tritium-hydrogen-deuterium (THD) with a density equivalent to DT. The fraction of D can be adjusted to control the neutron yield. Yields of ∼10 14-15 14 MeV (primary) neutrons are adequate to diagnose the hot spot as well as the dense fuel properties via down scattering of the primary neutrons. X-ray imaging diagnostics can function in this low yield environment providing additional information about the assembled fuel either by imaging the photons emitted by the hot central plasma, or by active probing of the dense shell by a separate high energy short pulse flash. The planned use of these targets and diagnostics to assess and optimize the assembly of the fuel and how this relates to the predicted performance of DT targets is described. It is found that a good predictor of DT target performance is the THD measurable parameter, Experimental Ignition Threshold Factor, ITFX ∼ Y x dsf 2.3 , where Y is the measured neutron yield between 13 and 15 MeV, and dsf is the down scattered neutron fraction defined as the ratio of neutrons between 10 and 12 MeV and those between 13 and 15 MeV.

Hybrid simulations of Z-Pinches in support of wire array implosion experiments at NTF

International Nuclear Information System (INIS)

Sotnikov, Vladimir Isaakovich; Oliver, Bryan Velten; Ivanov, Vladimir V.; LePell, Paul David; Fedin, Dmitry; Kantsyrev, Victor Leonidovich; Coverdale, Christine Anne; Travnicek, P.; Deeney, Christopher; Hellinger, P.; Jones, B.; Leboeuf, J.N.; Cowan, Thomas E.; Safronova, Alla S.

2005-01-01

Three-dimensional hybrid simulation of a plasma current-carrying column reveal two different regimes of sausage and kink instability development. In the first regime, with small Hall parameter, development of instabilities leads to the appearance of large-scale axial perturbations and eventually to bending of the plasma column. In the second regime, with a four-times-larger Hall parameter, small-scale perturbations dominate and no bending of the plasma column is observed. Simulation results are compared with laser probing experimental data obtained during wire array implosions on the Zebra pulse power generator at the Nevada Terawatt Facility.

Measuring neutron yield and ρR anisotropies with activation foils at the National Ignition Facility

Directory of Open Access Journals (Sweden)

Bleuel D.L.

2013-11-01

Full Text Available Neutron yields at the National Ignition Facility (NIF are measured with a suite of diagnostics, including activation of ∼20–200 g samples of materials undergoing a variety of energy-dependent neutron reactions. Indium samples were mounted on the end of a Diagnostic Instrument Manipulator (DIM, 25–50 cm from the implosion, to measure 2.45 MeV D-D fusion neutron yield. The 336.2 keV gamma rays from the 4.5 hour isomer of 115mIn produced by (n,n′ reactions are counted in high-purity germanium detectors. For capsules producing D-T fusion reactions, zirconium and copper are activated via (n,2n reactions at various locations around the target chamber and bay, measuring the 14 MeV neutron yield to accuracies on order of 7%. By mounting zirconium samples on ports at nine locations around the NIF chamber, anisotropies in the primary neutron emission due to fuel areal density asymmetries can be measured to a relative precision of 3%.

Development of target capsules for muon catalyzed fusion experiments

International Nuclear Information System (INIS)

Watts, K.D.; Jones, S.E.; Caffrey, A.J.

1983-01-01

A series of Muon Catalyzed Fusion experiments has been conducted at the Los Alamos Meson Physics Facility to determine how many fusion reactions one muon would catalyze under various temperature, pressure, contamination, and tritium concentration conditions. Target capsules to contain deuterium and tritium at elevated temperatures and pressures were engineered for a maximum temperature of 540 K (512 0 F) and a maximum pressure of 103 MPa (15,000 psig). Experimental data collected with these capsules indicated that the number of fusion reactions per muon continued to increase with temperature up to the 540-K design limit. Theory had indicated that the reaction rate should peak at approximately 540 K, but this was not confirmed during the experiments. A second generation of capsules which have a maximum design temperature of 800 K (980 0 F) and a maximum design pressure of 103 MPa (15,000 psig) has now been engineered. These new capsules will be used to further study the muon catalysis rate versus deuterium-tritium mixture temperature

Experimental configuration of direct drive cylindrical implosions on the Omega Laser

International Nuclear Information System (INIS)

Barnes, C.W.; Tubbs, D.L.; Beck, J.B.

1998-01-01

Details about the cylindrical implosions using direct-drive irradiation on the OMEGA Laser facility are provided. The experimental configuration, including orientation, construction, and mounting of the targets is described. An attempt to characterize the modulation transfer function of the primary x-ray framing camera diagnostic results in insufficient exposure contrast but relative agreement with other determinations. The x-ray intensity of the titanium backlighter driven by the 2.5-nsec linear ramp of the laser beams is described, and the relative intensity on film is compared to similar Nova experiments. The parallax effects of different length marker layers of high-opacity dichloropolystyrene is measured, resulting in the conclusion that the marker layer length should be matched to the laser drive illumination profile

Charged-particle spectroscopy for diagnosing shock ρR and strength in NIF implosions.

Science.gov (United States)

Zylstra, A B; Frenje, J A; Séguin, F H; Rosenberg, M J; Rinderknecht, H G; Johnson, M Gatu; Casey, D T; Sinenian, N; Manuel, M J-E; Waugh, C J; Sio, H W; Li, C K; Petrasso, R D; Friedrich, S; Knittel, K; Bionta, R; McKernan, M; Callahan, D; Collins, G W; Dewald, E; Döppner, T; Edwards, M J; Glenzer, S; Hicks, D G; Landen, O L; London, R; Mackinnon, A; Meezan, N; Prasad, R R; Ralph, J; Richardson, M; Rygg, J R; Sepke, S; Weber, S; Zacharias, R; Moses, E; Kilkenny, J; Nikroo, A; Sangster, T C; Glebov, V; Stoeckl, C; Olson, R; Leeper, R J; Kline, J; Kyrala, G; Wilson, D

2012-10-01

The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign diagnostic. The WRF measures the spectrum of protons from D-(3)He reactions in tuning-campaign implosions containing D and (3)He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total ρR through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

P2 asymmetry of Au's M-band flux and its smoothing effect due to high-Z ablator dopants

Directory of Open Access Journals (Sweden)

Yongsheng Li

2017-03-01

Full Text Available X-ray drive asymmetry is one of the main seeds of low-mode implosion asymmetry that blocks further improvement of the nuclear performance of “high-foot” experiments on the National Ignition Facility [Miller et al., Nucl. Fusion 44, S228 (2004]. More particularly, the P2 asymmetry of Au's M-band flux can also severely influence the implosion performance of ignition capsules [Li et al., Phys. Plasmas 23, 072705 (2016]. Here we study the smoothing effect of mid- and/or high-Z dopants in ablator on Au's M-band flux asymmetries, by modeling and comparing the implosion processes of a Ge-doped ignition capsule and a Si-doped one driven by X-ray sources with P2 M-band flux asymmetry. As the results, (1 mid- or high-Z dopants absorb hard X-rays (M-band flux and re-emit isotropically, which helps to smooth the asymmetric M-band flux arriving at the ablation front, therefore reducing the P2 asymmetries of the imploding shell and hot spot; (2 the smoothing effect of Ge-dopant is more remarkable than Si-dopant because its opacity in Au's M-band is higher than the latter's; and (3 placing the doped layer at a larger radius in ablator is more efficient. Applying this effect may not be a main measure to reduce the low-mode implosion asymmetry, but might be of significance in some critical situations such as inertial confinement fusion (ICF experiments very near the performance cliffs of asymmetric X-ray drives.

Expectations for the Laguna foil implosion experiments

International Nuclear Information System (INIS)

Greene, A.; Brownell, J.; Caird, R.; Goforth, J.; Price, R.; Trainor, J.

1987-01-01

Building on the results achieved in the Pioneer shot series, the Los Alamos Trailmaster project is embarking on the Laguna foil implosion experiments. In this series a Mark-IX helical generator will be coupled to an explosively formed fuse opening switch, a surface-tracking closing switch, and a vacuum power flow and load chamber. In this paper the system design will be discussed and results from zero-, one-, and two-dimensional MHD simulations will be presented. It is anticipated that the generator will provide more than 10 MA of which ∼5.5 MA will be switched to the 5-cm-radius, 2-cm-high, 250-nm-thick aluminum foil load. This should give rise to a 1 μs implosion with more than 100 kJ of kinetic energy

The use of tritium rich capsules with 25-35% deuterium to achieve ignition at the National Ignition Facility

Science.gov (United States)

Wilson, D. C.; Spears, B. K.; Hatchett, S. P., Ii; Cerjan, C. J.; Springer, P. T.; Clark, D. S.; Edwards, M. J.; Salmonson, J. D.; Weber, S. V.; Hammel, B. A.; Grim, G. P.; Herrmann, H. W.; Wilke, M. D.

2010-08-01

Diagnostics such as neutron yield, ion temperature, image size and shape, and bang time in capsules with >~25 % deuterium fuel show changes due to burn product heating. The comparison of performance between a THD(2%) and THD(35%) can help predict ignition in a TD(50%) capsule. Surrogacy of THD capsules to TD(50%) is incomplete due to variations in fuel molecular vapour pressures. TD(25-35%) capsules might be preferred to study hot spot heating, but at the risk of increased fuel/ablator mixing.

The use of tritium rich capsules with 25-35% deuterium to achieve ignition at the National Ignition Facility

International Nuclear Information System (INIS)

Wilson, D C; Grim, G P; Herrmann, H W; Wilke, M D; Spears, B K; Ii, S P Hatchett; Cerjan, C J; Springer, P T; Clark, D S; Edwards, M J; Salmonson, J D; Weber, S V; Hammel, B A

2010-01-01

Diagnostics such as neutron yield, ion temperature, image size and shape, and bang time in capsules with >∼25 % deuterium fuel show changes due to burn product heating. The comparison of performance between a THD(2%) and THD(35%) can help predict ignition in a TD(50%) capsule. Surrogacy of THD capsules to TD(50%) is incomplete due to variations in fuel molecular vapour pressures. TD(25-35%) capsules might be preferred to study hot spot heating, but at the risk of increased fuel/ablator mixing.

The use of tritium rich capsules with 25-35% deuterium to achieve ignition at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Wilson, D C; Grim, G P; Herrmann, H W; Wilke, M D [Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Spears, B K; Ii, S P Hatchett; Cerjan, C J; Springer, P T; Clark, D S; Edwards, M J; Salmonson, J D; Weber, S V; Hammel, B A, E-mail: dcw@lanl.go [Lawrence Livermore National Laboratory, Livermore, CA, 94550 (United States)

2010-08-01

Diagnostics such as neutron yield, ion temperature, image size and shape, and bang time in capsules with >{approx}25 % deuterium fuel show changes due to burn product heating. The comparison of performance between a THD(2%) and THD(35%) can help predict ignition in a TD(50%) capsule. Surrogacy of THD capsules to TD(50%) is incomplete due to variations in fuel molecular vapour pressures. TD(25-35%) capsules might be preferred to study hot spot heating, but at the risk of increased fuel/ablator mixing.

Impeding hohlraum plasma stagnation in inertial-confinement fusion.

Science.gov (United States)

Li, C K; Séguin, F H; Frenje, J A; Rosenberg, M J; Rinderknecht, H G; Zylstra, A B; Petrasso, R D; Amendt, P A; Landen, O L; Mackinnon, A J; Town, R P J; Wilks, S C; Betti, R; Meyerhofer, D D; Soures, J M; Hund, J; Kilkenny, J D; Nikroo, A

2012-01-13

This Letter reports the first time-gated proton radiography of the spatial structure and temporal evolution of how the fill gas compresses the wall blowoff, inhibits plasma jet formation, and impedes plasma stagnation in the hohlraum interior. The potential roles of spontaneously generated electric and magnetic fields in the hohlraum dynamics and capsule implosion are discussed. It is shown that interpenetration of the two materials could result from the classical Rayleigh-Taylor instability occurring as the lighter, decelerating ionized fill gas pushes against the heavier, expanding gold wall blowoff. This experiment showed new observations of the effects of the fill gas on x-ray driven implosions, and an improved understanding of these results could impact the ongoing ignition experiments at the National Ignition Facility.

A new metric of the low-mode asymmetry for ignition target designs

International Nuclear Information System (INIS)

Gu, Jianfa; Dai, Zhensheng; Fan, Zhengfeng; Zou, Shiyang; Ye, Wenhua; Pei, Wenbing; Zhu, Shaoping

2014-01-01

In the deuterium-tritium inertial confinement fusion implosion experiments on the National Ignition Facility, the measured neutron yield and hot spot pressure are significantly lower than simulations. Understanding the underlying physics of the deficit is essential to achieving ignition. This paper investigates the low-mode areal density asymmetry in the main fuel of ignition capsule. It is shown that the areal density asymmetry breaks up the compressed shell and significantly reduces the conversion of implosion kinetic energy to hot spot internal energy, leading to the calculated hot spot pressure and neutron yield quite close to the experimental data. This indicates that the low-mode shell areal density asymmetry can explain part of the large discrepancy between simulations and experiments. Since only using the hot spot shape term could not adequately characterize the effects of the shell areal density asymmetry on implosion performance, a new metric of the low-mode asymmetry is developed to accurately measure the probability of ignition

Investigation of trailing mass in Z-pinch implosions and comparison to experiment

Science.gov (United States)

Yu, Edmund

2007-11-01

Wire-array Z pinches represent efficient, high-power x-ray sources with application to inertial confinement fusion, high energy density plasmas, and laboratory astrophysics. The first stage of a wire-array Z pinch is described by a mass ablation phase, during which stationary wires cook off material, which is then accelerated radially inwards by the JxB force. The mass injection rate varies axially and azimuthally, so that once the ablation phase concludes, the subsequent implosion is highly 3D in nature. In particular, a network of trailing mass and current is left behind the imploding plasma sheath, which can significantly affect pinch performance. In this work we focus on the implosion phase, electing to model the mass ablation via a mass injection scheme. Such a scheme has a number of injection parameters, but this freedom also allows us to gain understanding into the nature of the trailing mass network. For instance, a new result illustrates the role of azimuthal correlation. For an implosion which is 100% azimuthally correlated (corresponding to an azimuthally symmetric 2D r-z problem), current is forced to flow on the imploding plasma sheath, resulting in strong Rayleigh-Taylor (RT) growth. If, however, the implosion is not azimuthally symmetric, the additional azimuthal degree of freedom opens up new conducting paths of lower magnetic energy through the trailing mass network, effectively reducing RT growth. Consequently the 3D implosion experiences lower RT growth than the 2D r-z equivalent, and actually results in a more shell-like implosion. A second major goal of this work is to constrain the injection parameters by comparison to a well-diagnosed experimental data set, in which array mass was varied. In collaboration with R. Lemke, M. Desjarlais, M. Cuneo, C. Jennings, D. Sinars, E. Waisman

Nuclear Probing of Dense Plasmas

International Nuclear Information System (INIS)

Richard Petrasso

2007-01-01

The object of inertial confinement fusion (ICF) is to compress a fuel capsule to a state with high enough density and temperature to ignite, starting a self-sustaining fusion burn that consumes much of the fuel and releases a large amount of energy. The national ICF research program is trying to reach this goal, especially through experiments at the OMEGA laser facility of the University of Rochester Laboratory of Laser Energetics (LLE), planned experiments at the National Ignition Facility (NIF) under construction at the Lawrence Livermore National Laboratory (LLNL), and experimental and theoretical work at other national laboratories. The work by MIT reported here has played several important roles in this national program. First, the development of new and improved charged-particle-based plasma diagnostics has allowed the gathering of new and unique diagnostic information about the implosions of fuel capsules in ICF experiments, providing new means for evaluating experiments and for studying capsule implosion dynamics. Proton spectrometers have become the standard for evaluating the mass assembly in compressed capsules in experiments at OMEGA; the measured energy downshift of either primary or secondary D3He fusion protons to determines the areal density, or ?R, of imploded capsules. The Proton Temporal Diagnostic measures the time history of fusion burn, and multiple proton emission imaging cameras reveal the 3-D spatial distribution of fusion burn. A new compact neutron spectrometer, for measuring fusion yield, is described here for the first time. And of especially high importance to future work is the Magnetic Recoil Spectrometer (MRS), which is a neutron spectrometer that will be used to study a range of important performance parameters in future experiments at the NIF. A prototype is currently being prepared for testing at OMEGA, using a magnet funded by this grant. Second, MIT has used these diagnostic instruments to perform its own physics experiments

Nuclear Probing of Dense Plasmas

Energy Technology Data Exchange (ETDEWEB)

Richard Petrasso

2007-02-14

The object of inertial confinement fusion (ICF) is to compress a fuel capsule to a state with high enough density and temperature to ignite, starting a self-sustaining fusion burn that consumes much of the fuel and releases a large amount of energy. The national ICF research program is trying to reach this goal, especially through experiments at the OMEGA laser facility of the University of Rochester Laboratory of Laser Energetics (LLE), planned experiments at the National Ignition Facility (NIF) under construction at the Lawrence Livermore National Laboratory (LLNL), and experimental and theoretical work at other national laboratories. The work by MIT reported here has played several important roles in this national program. First, the development of new and improved charged-particle-based plasma diagnostics has allowed the gathering of new and unique diagnostic information about the implosions of fuel capsules in ICF experiments, providing new means for evaluating experiments and for studying capsule implosion dynamics. Proton spectrometers have become the standard for evaluating the mass assembly in compressed capsules in experiments at OMEGA; the measured energy downshift of either primary or secondary D3He fusion protons to determines the areal density, or ?R, of imploded capsules. The Proton Temporal Diagnostic measures the time history of fusion burn, and multiple proton emission imaging cameras reveal the 3-D spatial distribution of fusion burn. A new compact neutron spectrometer, for measuring fusion yield, is described here for the first time. And of especially high importance to future work is the Magnetic Recoil Spectrometer (MRS), which is a neutron spectrometer that will be used to study a range of important performance parameters in future experiments at the NIF. A prototype is currently being prepared for testing at OMEGA, using a magnet funded by this grant. Second, MIT has used these diagnostic instruments to perform its own physics experiments

A study of CR-39 track response to charged particles from NOVA implosions

International Nuclear Information System (INIS)

Phillips, T.W.; Cable, M.D.; Hicks, D.G.; Li, C.K.; Petrasso, R.D.; Seguin, F.H.

1996-01-01

We have exposed CR-39 track recording material to a number of NOVA implosions. Radiation from the implosion passed through an array of ranging filters, which aided identification of the incident particles and their energies. The etching procedure was calibrated by including a piece of track exposed to DD protons from a small accelerator. For the same shots, we quantitatively compare the DD neutron yield with the DD proton yield determined from the track. In DT implosions, tracks produced by neutron interactions prevent observation of charged-particle tracks that are produced by the processes of knock-on, secondary or tertiary fusion

Three-Dimensional Hydrodynamic Simulations of the Effects of Laser Imprint in OMEGA Implosions

Science.gov (United States)

Igumenshchev, I. V.; Campbell, E. M.; Goncharov, V. N.; Regan, S. P.; Shvydky, A.; Schmitt, A. J.

2017-10-01

Illumination of direct-drive implosion targets by the OMEGA laser introduces large-amplitude broadband modulations in the absorbed energy from the largest (target size 900- μm) to smallest (speckle size 2- μm) spatial scales. These modulations ``imprint'' perturbations into a target that are amplified because of the secular and Rayleigh-Taylor growths during acceleration and deceleration of the target. The degradation of performance of room-temperature and cryogenic OMEGA implosions caused by these perturbations were simulated in three dimensions using the code ASTER. The highest-resolution simulations resolve perturbation modes as high as l 200 . The high modes l 50to 100 dominate in the perturbation spectrum during the linear growth, while the late-time nonlinear evolution results in domination of modes with l 30to 50 . Smoothing by spectral dispersion reduces the linear-phase mode amplitudes by a factor of 4 and results in substantial improvements in implosion performance that is in good agreement with measurements. The effects of imprint on implosion performance are compared with the effects of other implosion asymmetries, such as those induced because of laser beam imbalance, mistiming and mispointing, and target offset. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Super-fast multi-wire liner implosion physics study at Angara-5-1

Energy Technology Data Exchange (ETDEWEB)

Alexandrov, V V; Branitsky, A V; Volkov, G S; Fedulov, M V; Grabovsky, E V; Nedoseev, L; Oleinik, G M; Samokhin, A N; Sasorov, F P.V.; Smirnov, V P; Frolov, I N; Zaitzev, V I; Zurin, M V [GSC Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow region (Russian Federation); Spielman, R B; Deeney, C [Sandia National Labs., Albuquerque, NM (United States)

2000-07-01

The temporally dragged plasma production (TDPP) from dense substance of tungsten wire occurs during multi-wire-liner implosion. TDPP is the typical feature of wire liner implosion. In spite of plasma filling of the initial liner cavity, a narrow pulse (up to 6 ns) of X rays is radiated for an 0.3-mm inter-wire gap. (authors)

Super-fast multi-wire liner implosion physics study at Angara-5-1

International Nuclear Information System (INIS)

Alexandrov, V.V.; Branitsky, A.V.; Volkov, G.S.; Fedulov, M.V.; Grabovsky, E.V.; Nedoseev, L.; Oleinik, G.M.; Samokhin, A.N.; Sasorov, F.P.V.; Smirnov, V.P.; Frolov, I.N.; Zaitzev, V.I.; Zurin, M.V.; Spielman, R.B.; Deeney, C.

2000-01-01

The temporally dragged plasma production (TDPP) from dense substance of tungsten wire occurs during multi-wire-liner implosion. TDPP is the typical feature of wire liner implosion. In spite of plasma filling of the initial liner cavity, a narrow pulse (up to 6 ns) of X rays is radiated for an 0.3-mm inter-wire gap. (authors)

Development of the power ramping facility at JMTR

International Nuclear Information System (INIS)

Nakata, Hirokatsu; Sezaki, Katsuji; Nakazaki, Chosaburo; Ishii, Tadahiko; Ito, Haruhiko; Abe, Hiroshi

1985-03-01

The LWR fuel power ramping facility have been being developed at JMTR since 1978. This report, following previous reports, JAERI-M 8533 and 9343, summarizes the results of performance test performed in 1981 on the 3 He power controlled boiling water capsule, which is a basic part of the facility. Various measurements were carried out during reactor operation on each part of the capsule, i.e. capsule itself, capsule control unit and 3 He power control unit, after a long-time cold run test of the units. Through the test, it was confirmed that the capsule satisfies the specifications which stated that LWR fuel pin should be power-ramped under BWR conditions up to 50 kW/m with a change factor of more than 2, and that the control units operate in a good condition. (author)

Implosion characteristics of deuterium--tritium pellets surrounded by high-density shells

International Nuclear Information System (INIS)

Fraley, G.S.

1976-09-01

The effect of high-density shells on deuterium-tritium pellets imploded by laser energy deposition or other means is investigated. Attention is centered on the inner parts of the pellet where hydrodynamics is the dominant mechanism. The implosions can then be characterized by a pressure boundary condition. Numerical solutions of the implosions are carried out over a wide range of parameters both for solid pellets and pellets with a central void

Diagnostics for Z-pinch implosion experiments on PTS

Energy Technology Data Exchange (ETDEWEB)

Ren, X. D., E-mail: amosrxd@163.com; Huang, X. B., E-mail: amosrxd@163.com; Zhou, S. T., E-mail: amosrxd@163.com; Zhang, S. Q., E-mail: amosrxd@163.com; Dan, J. K., E-mail: amosrxd@163.com; Li, J., E-mail: amosrxd@163.com; Cai, H. C., E-mail: amosrxd@163.com; Wang, K. L., E-mail: amosrxd@163.com; Ouyang, K., E-mail: amosrxd@163.com; Xu, Q., E-mail: amosrxd@163.com; Duan, S. C., E-mail: amosrxd@163.com; Chen, G. H., E-mail: amosrxd@163.com; Wang, M., E-mail: amosrxd@163.com; Feng, S. P., E-mail: amosrxd@163.com; Yang, L. B., E-mail: amosrxd@163.com; Xie, W. P., E-mail: amosrxd@163.com; Deng, J. J., E-mail: amosrxd@163.com [Key Lab of Pulsed Power, Institute of Fluid Physics, CAEP, P.O. Box 919-108, Mianyang, Sichuan 621999 (China)

2014-12-15

The preliminary experiments of wire array implosion were performed on PTS, a 10 MA z-pinch driver with a 70 ns rise time. A set of diagnostics have been developed and fielded on PTS to study pinch physics and implosion dynamics of wire array. Radiated power measurement for soft x-rays was performed by multichannel filtered x-ray diode array, and flat spectral responses x-ray diode detector. Total x-ray yield was measured by a calibrated, unfiltered nickel bolometer which was also used to obtain pinch power. Multiple time-gated pinhole cameras were used to produce spatial-resolved images of x-ray self-emission from plasmas. Two time-integrated pinhole cameras were used respectively with 20-μm Be filter and with multilayer mirrors to record images produced by >1-keV and 277±5 eV self-emission. An optical streak camera was used to produce radial implosion trajectories, and an x-ray streak camera paired with a horizontal slit was used to record a continuous time-history of emission with one-dimensional spatial resolution. A frequency-doubled Nd:YAG laser (532 nm) was used to produce four frame laser shadowgraph images with 6 ns time interval. We will briefly describe each of these diagnostics and present some typical results from them.

Production of hollow microspheres for inertial confinement fusion experiments

International Nuclear Information System (INIS)

Cook, R.

1994-12-01

The targets used in inertial confinement fusion (ICF) experiments at the Lawrence Livermore National Laboratory are plastic capsules roughly 0.5 mm in diameter. The capsules, which typically have wall thicknesses from 20 to 60 μm, must possess extraordinary symmetry and concentricity and must have surface finishes of less than 1000 Angstrom peak-to-valley variation over surface contours of from 10 to 100's of μm. This paper reviews the fabrication of these capsules, focusing on the production of the thin-walled polystyrene microshell mandrel around which the capsule is built. The relationship between the capsule characteristics, especially surface finish, and capsule performance is discussed, as are the methods of surface characterization and modification necessary for experiments designed to study the effects of surface roughness on implosion dynamics. Targets for the next generation of ICF facilities using more powerful laser drivers will have to be larger while meeting the same or even more stringent symmetry and surface finish requirements. Some of the technologies for meeting these needs are discussed briefly

Influence of argon impurities on the elastic scattering of x-rays from imploding beryllium capsules

Science.gov (United States)

Saunders, A. M.; Chapman, D. A.; Kritcher, A. L.; Schoff, M.; Shuldberg, C.; Landen, O. L.; Glenzer, S. H.; Falcone, R. W.; Gericke, D. O.; Döppner, T.

2018-03-01

We investigate the effect of argon impurities on the elastic component of x-ray scattering spectra taken from directly driven beryllium capsule implosions at the OMEGA laser. The plasma conditions were obtained in a previous analysis [18] by fitting the inelastic scattering component. We show that the known argon impurity in the beryllium modifies the elastic scattering due to the larger number of bound electrons. We indeed find significant deviations in the elastic scattering from roughly 1 at.% argon contained in the beryllium. With knowledge of the argon impurity fraction, we use the elastic scattering component to determine the charge state of the compressed beryllium, as the fits are rather insensitive to the argon charge state. Finally, we discuss how doping small fractions of mid- or high-Z elements into low-Z materials could allow ionization balance studies in dense plasmas.

Planar hydrodynamic instability computations and experiments with rugby-shaped hohlraums at the Omega laser

International Nuclear Information System (INIS)

Vandenboomgaerde, M; Liberatore, S; Galmiche, D; Casner, A; Huser, G; Jadaud, J P; Villette, B

2008-01-01

Implosion of inertial confinement fusion (ICF) capsule is very sensitive to the growth of sphericity perturbations. The control of the feeding of such perturbations and their transport ('feedthrough') through the ablator is a key point to reach ignition. Since 2002, experiments have been designed and performed on the Omega laser facility in order to study these phenomena in planar geometry. A new 'rugby shaped' hohlraum was used. We present experimental results and comparisons with numerical simulations

Radiography in the X-ray region of a laser implosed microball

International Nuclear Information System (INIS)

Launspach, J.; Bayer, C.; Billon, D.; Decroisette, M.; Juraszek, D.; Meynial, D.

1981-05-01

The OCTAL laser of the Limeil CEA Research Center was used to realize the implosion of small targets containing a mixture of DT and to produce thermonuclear fusion reactions. The experimental device in which the experiments were carried out is called Camelia. Its main component is a vacuum chamber upon which the following elements are fixed: - devices for adjusting the focussing lenses; - a device for positioning targets; - extensive diagnostic means enabling the maximum amount of information to be obtained from each shot. These experiments were performed in order to study laser implosion mechanisms and to measure the density and temperature characteristics that can be reached in this way. The X-ray radiography device is relatively simple. It consists of an X-ray source, the target to be analyzed, one or two stenopies and a detector which is either a simple film (Kodak Kodirex) for diagnostics without temporal resolution or a scanning camera with a slit when temporal resolution is required. The device can be used: - without an x-ray source for emission diagnostics with spatio-temporal resolution, - to study the pre-heating of targets by radiography of the dust at the beginning of the implosion, - for diagnostics of the plasma core by radiography of dust after the implosion [fr

Validity and Utilization of the Out-Pile Testing Facilities at HANARO

Energy Technology Data Exchange (ETDEWEB)

Choo, Kee-Nam; Cho, Man-Soon; Yang, Sung-Woo; Shin, Yoon-Taek; Park, Seng-Jae; Jun, Byung-Hyuk; Kim, Myong-Seop [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

Various neutron irradiation facilities such as rabbit irradiation facilities, loop facilities and the capsule irradiation facilities for irradiation tests of nuclear materials, fuels and radioisotope products have been developed at HANARO. Among these irradiation facilities, the capsule is the most useful device for coping with the various test requirements at HANARO. To support the national research and development programs on nuclear reactors and the nuclear fuel cycle technology in Korea, new irradiation capsules have been developed and actively utilized for the irradiation tests requested by numerous users. The environmental conditions for these reactors are generally beyond present day reactor technology, especially regarding the higher neutron fluence and higher operating temperature. To effectively support the national R and Ds relevant to the future nuclear systems, the development of advanced irradiation technologies concerning higher neutron fluence and irradiation temperature are being preferentially developed at HANARO. The utilization of the out-pile testing facilities to satisfy the criteria of safety evaluation for a new device installed in the core of HANARO was summarized. In addition, the validity of the out-pile testing facilities was evaluated and proved to be effective for verifying the integrity of irradiation capsule.

Validity and Utilization of the Out-Pile Testing Facilities at HANARO

International Nuclear Information System (INIS)

Choo, Kee-Nam; Cho, Man-Soon; Yang, Sung-Woo; Shin, Yoon-Taek; Park, Seng-Jae; Jun, Byung-Hyuk; Kim, Myong-Seop

2016-01-01

Various neutron irradiation facilities such as rabbit irradiation facilities, loop facilities and the capsule irradiation facilities for irradiation tests of nuclear materials, fuels and radioisotope products have been developed at HANARO. Among these irradiation facilities, the capsule is the most useful device for coping with the various test requirements at HANARO. To support the national research and development programs on nuclear reactors and the nuclear fuel cycle technology in Korea, new irradiation capsules have been developed and actively utilized for the irradiation tests requested by numerous users. The environmental conditions for these reactors are generally beyond present day reactor technology, especially regarding the higher neutron fluence and higher operating temperature. To effectively support the national R and Ds relevant to the future nuclear systems, the development of advanced irradiation technologies concerning higher neutron fluence and irradiation temperature are being preferentially developed at HANARO. The utilization of the out-pile testing facilities to satisfy the criteria of safety evaluation for a new device installed in the core of HANARO was summarized. In addition, the validity of the out-pile testing facilities was evaluated and proved to be effective for verifying the integrity of irradiation capsule

THERMAL NEUTRON FLUX MAPPING ON A TARGET CAPSULE AT RABBIT FACILITY OF RSG-GAS REACTOR FOR USE IN k0-INAA

Directory of Open Access Journals (Sweden)

Sutisna Sutisna

2015-03-01

Full Text Available Instrumental neutron activation analysis based on the k0 method (k0-INAA requires the availability of the accurate reactor parameter data, in particular a thermal neutron flux that interact with a targets inside the target capsule. This research aims to determine and map the thermal neutron flux inside the capsule and irradiation channels used for the elemental quantification using the k0-AANI. Mapping of the thermal neutron flux (фth on two type of irradiation capsule have been done for RS01 and RS02 facilities of RSG-GAS reactor. Thermal neutron flux determined using Al-0,1%Au alloy through 197Au(n,g 198Au nuclear reaction, while the flux mapping done using statistics R. Thermal neutron flux are calculated using k0-IAEA software provided by IAEA. The results showed the average thermal neutron flux is (5.6±0.3×10+13 n.cm-2.s-1; (5.6±0.4×10+13 n.cm-2.s-1; (5.2±0.4×10+13 n.cm-2.s-1 and (5.3±0.4×10+13 n.cm-2.s-1 for Polyethylene capsule of 1st , 2nd, 3rd and 4th layer respectively. In the case of Aluminum capsule, the thermal neutron flux was lower compared to that on Polyethylene capsule. There were (3.0±0.2×10+13 n.cm-2.s-1; (2.8±0.1×10+13 n.cm-2.s-1; (3.2±0.3×10+13 n.cm-2.s-1 for 1st, 2nd and 3rd layers respectively. For each layer in the capsule, the thermal neutron flux is not uniform and it was no degradation flux in the axial direction, both for polyethylene and aluminum capsules. Contour map of eight layer on polyethylene capsule and six layers on aluminum capsule for RS01 and RS02 irradiation channels had a similar pattern with a small diversity for all type of the irradiation capsule. Keywords: thermal neutron, flux, capsule, NAA   Analisis aktivasi neutron instrumental berbasis metode k0 (k0-AANI memerlukan ketersediaan data parameter reaktor yang akurat, khususnya data fluks neutron termal yang berinteraksi dengan inti sasaran di dalam kapsul target. Penelitian ini bertujuan menentukan dan memetakan fluks neutron termal

Simulation of the implosion of a theta pinch

International Nuclear Information System (INIS)

Busnardo Neto, J.; Leite Neto, J.P.; Jesus Paes, A.C. de

1982-01-01

A two-fluid model was used to simulate the implosion of a theta-pinch, with initial densities varying from 10 12 to 10 16 cm -3 . The gases used were hydrogen, helium, neon and argon; initial temperatures of 2 eV and total ionization were assumed. For hydrogen the anomalous resistivity is dominant everywhere when the density is low (ν sub(eff) - ω sub(pi)). For high densities both resistivities are not high enough to allow diffusion of the magnetic field during the time of the implosion (ν sub(eff) approximatelly 0.3 ω sub(pi)). For heavier gases a surprisingly high value of the anomalous resistivity was found, due to the greater mass, (ν sub(eff) approximatelly 10-12 ω sub(pi)). (Author) [pt

Energy balance during underwater implosion of ductile metallic cylinders.

Science.gov (United States)

Chamberlin, Ryan E; Guzas, Emily L; Ambrico, Joseph M

2014-11-01

Energy-based metrics are developed and applied to a numerical test case of implosion of an underwater pressure vessel. The energy metrics provide estimates of the initial energy in the system (potential energy), the energy released into the fluid as a pressure pulse, the energy absorbed by the imploding structure, and the energy absorbed by air trapped within the imploding structure. The primary test case considered is the implosion of an aluminum cylinder [diameter: 2.54 cm (1 in.), length: 27.46 cm (10.81 in.)] that collapses flat in a mode-2 shape with minimal fracture. The test case indicates that the structure absorbs the majority (92%) of the initial energy in the system. Consequently, the energy emitted as a pressure pulse into the fluid is a small fraction, approximately 5%, of the initial energy. The energy absorbed by the structure and the energy emitted into the fluid are calculated for additional simulations of underwater pressure vessel implosions. For all cases investigated, there is minimal fracture in the collapse, the structure absorbs more than 80% of the initial energy of the system, and the released pressure pulse carries away less than 6% of the initial energy.

Progress towards ignition on the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Edwards, M. J.; Patel, P. K.; Lindl, J. D.; Atherton, L. J.; Glenzer, S. H.; Haan, S. W.; Landen, O. L.; Moses, E. I.; Springer, P. T.; Benedetti, R.; Bernstein, L.; Bleuel, D. L.; Bradley, D. K.; Caggiano, J. A.; Callahan, D. A.; Celliers, P. M.; Cerjan, C. J.; Clark, D. S.; Collins, G. W.; Dewald, E. L. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); and others

2013-07-15

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory includes a precision laser system now capable of delivering 1.8 MJ at 500 TW of 0.35-μm light to a target. NIF has been operational since March 2009. A variety of experiments have been completed in support of NIF's mission areas: national security, fundamental science, and inertial fusion energy. NIF capabilities and infrastructure are in place to support its missions with nearly 60 X-ray, optical, and nuclear diagnostic systems. A primary goal of the National Ignition Campaign (NIC) on the NIF was to implode a low-Z capsule filled with ∼0.2 mg of deuterium-tritium (DT) fuel via laser indirect-drive inertial confinement fusion and demonstrate fusion ignition and propagating thermonuclear burn with a net energy gain of ∼5–10 (fusion yield/input laser energy). This requires assembling the DT fuel into a dense shell of ∼1000 g/cm{sup 3} with an areal density (ρR) of ∼1.5 g/cm{sup 2}, surrounding a lower density hot spot with a temperature of ∼10 keV and a ρR ∼0.3 g/cm{sup 2}, or approximately an α-particle range. Achieving these conditions demand precise control of laser and target parameters to allow a low adiabat, high convergence implosion with low ablator fuel mix. We have demonstrated implosion and compressed fuel conditions at ∼80–90% for most point design values independently, but not at the same time. The nuclear yield is a factor of ∼3–10× below the simulated values and a similar factor below the alpha dominated regime. This paper will discuss the experimental trends, the possible causes of the degraded performance (the off-set from the simulations), and the plan to understand and resolve the underlying physics issues.

Transient phenomena in the final implosion stage at the PF-1000 facility

International Nuclear Information System (INIS)

Gribkov, V.A.; Banaszak, A.; Jakubowski, L.; Sadowski, M.J.; Szydlowski, A.; Bienkowska, B.; Borowiecki, M.; Ivanova-Stanik, I.; Karpinski, L.; Miklaszewski, R.A.; Paduch, M.; Scholz, M.; Tomaszewski, K.; Dubrovsky, A.V.

2006-12-01

This paper consists of two parts, which are essentially constituted as a single whole. Dense Plasma Focus device (DPF), which is known from the early 50's, is the oldest machine which has survived since the very beginning of thermonuclear researches. This is a high voltage high-current pulsed discharge, which is produced usually by a discharge of a capacitor bank in various gases. It consists of two coaxial electrodes with the central one (anode) spanned by a ring insulator. The device is known in two configurations of electrodes named by their creators - the Filippov type (in year 1954) and the Mather one (1961). The first configuration, elaborated in the Kurchatov Institute for Atomic Energy, Moscow, Russia, has a flat anode of disc shape lying directly on the upper edge of an insulator and a cathode ('liner') looks like a pan turned up-side down and covers the anode from the top. This is a relatively infrequent modification used at the present time in two or three centres. The second one was elaborated in the Los Alamos scientific laboratory, USA, and this has an anode in the shape of a tube with a flat lid on the top of it. Cathode is usually made in the form of a squirrel cage, i.e. containing a number of rods placed along the circumference around the anode tube. These devices on the low level of the energy stored in the bank are important due to their numerous applications. The upper level of the bank energy reached at present is interesting because of its perspectives as a unique neutron source for use in nuclear physics and radiation material sciences. The main processes taking place during a development of the discharge is described in this paper. Here we shall mention that the paper is devoted to investigations of physical processes taking place in the PF-1000 facility. This device was put into operation with full energy stored in the bank at the Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland, about two years ago. The energy in the bank

Self-generated magnetic fields in direct-drive implosion experiments

Energy Technology Data Exchange (ETDEWEB)

Igumenshchev, I. V.; Nilson, P. M.; Goncharov, V. N. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623 (United States); Zylstra, A. B.; Li, C. K.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2014-06-15

Electric and self-generated magnetic fields in direct-drive implosion experiments on the OMEGA Laser Facility were investigated employing radiography with ∼10- to 60-MeV protons. The experiment used plastic-shell targets with imposed surface defects (glue spots, wires, and mount stalks), which enhance self-generated fields. The fields were measured during the 1-ns laser drive with an on-target intensity ∼10{sup 15} W/cm{sup 2}. Proton radiographs show multiple ring-like structures produced by electric fields ∼10{sup 7} V/cm and fine structures from surface defects, indicating self-generated fields up to ∼3 MG. These electric and magnetic fields show good agreement with two-dimensional magnetohydrodynamic simulations when the latter include the ∇T{sub e} × ∇n{sub e} source, Nernst convection, and anisotropic resistivity. The simulations predict that self-generated fields affect heat fluxes in the conduction zone and, through this, affect the growth of local perturbations.

Nuclear diagnostics for inertial confinement fusion implosions

International Nuclear Information System (INIS)

Murphy, T.J.

1997-01-01

This abstract contains viewgraphs on nuclear diagnostic techniques for inertial confinement fusion implosions. The viewgraphs contain information on: reactions of interest in ICF; advantages and disadvantages of these methods; the properties nuclear techniques can measure; and some specifics on the detectors used

Implosive Therapy as a Treatment for Insomnia.

Science.gov (United States)

Carrera, Richard N.; Elenewski, Jeffrey J.

1980-01-01

The death implosion produced a decrease in insomnia beyond the strong expectancy effects that resulted from all experimental treatments. The failure to observe changes in reported fear of death was attributed to subjects' anxiety-based reluctance to acknowledge openly such fear. (Author)

Spiral wobbling beam illumination uniformity in HIF fuel target implosion

Directory of Open Access Journals (Sweden)

Kawata S.

2013-11-01

Full Text Available A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF throughout the heavy ion beam (HIB driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may produce a time-dependent implosion acceleration, which reduces the Rayleigh-Taylor (R-T growth [Laser Part. Beams 11, 757 (1993, Nuclear Inst. Methods in Phys. Res. A 606, 152 (2009, Phys. Plasmas 19, 024503 (2012] and the implosion nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ∼ 1 GHz [Phys. Rev. Lett. 104, 254801 (2010]. Three-dimensional HIBs illumination computations present that the few % wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency.

A Comparison of Implosive Therapy and Systematic Desensitization in the Treatment of Test Anxiety

Science.gov (United States)

Smith, Ronald E.; Nye, S. Lee

1973-01-01

Both Desensitization and implosive therapy resulted in significant decreases in scores on Sarason's Test Anxiety Scale. However, the desensitization group also demonstrated a significant reduction in state anxiety assessed during simulated testing sessions and a significant increase in grade point average, while the implosive therapy group showed…

An in-flight radiography platform to measure hydrodynamic instability growth in inertial confinement fusion capsules at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Raman, K. S.; Smalyuk, V. A.; Casey, D. T.; Haan, S. W.; Hurricane, O. A.; Kroll, J. J.; Peterson, J. L.; Remington, B. A.; Robey, H. F.; Clark, D. S.; Hammel, B. A.; Landen, O. L.; Marinak, M. M.; Munro, D. H.; Salmonson, J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hoover, D. E.; Nikroo, A. [General Atomics, San Diego, California 92121 (United States); Peterson, K. J. [Sandia National Laboratory, Albuquerque, New Mexico 87125 (United States)

2014-07-15

A new in-flight radiography platform has been established at the National Ignition Facility (NIF) to measure Rayleigh–Taylor and Richtmyer–Meshkov instability growth in inertial confinement fusion capsules. The platform has been tested up to a convergence ratio of 4. An experimental campaign is underway to measure the growth of pre-imposed sinusoidal modulations of the capsule surface, as a function of wavelength, for a pair of ignition-relevant laser drives: a “low-foot” drive representative of what was fielded during the National Ignition Campaign (NIC) [Edwards et al., Phys. Plasmas 20, 070501 (2013)] and the new high-foot [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park et al., Phys. Rev. Lett. 112, 055001 (2014)] pulse shape, for which the predicted instability growth is much lower. We present measurements of Legendre modes 30, 60, and 90 for the NIC-type, low-foot, drive, and modes 60 and 90 for the high-foot drive. The measured growth is consistent with model predictions, including much less growth for the high-foot drive, demonstrating the instability mitigation aspect of this new pulse shape. We present the design of the platform in detail and discuss the implications of the data it generates for the on-going ignition effort at NIF.

An in-flight radiography platform to measure hydrodynamic instability growth in inertial confinement fusion capsules at the National Ignition Facility

International Nuclear Information System (INIS)

Raman, K. S.; Smalyuk, V. A.; Casey, D. T.; Haan, S. W.; Hurricane, O. A.; Kroll, J. J.; Peterson, J. L.; Remington, B. A.; Robey, H. F.; Clark, D. S.; Hammel, B. A.; Landen, O. L.; Marinak, M. M.; Munro, D. H.; Salmonson, J.; Hoover, D. E.; Nikroo, A.; Peterson, K. J.

2014-01-01

A new in-flight radiography platform has been established at the National Ignition Facility (NIF) to measure Rayleigh–Taylor and Richtmyer–Meshkov instability growth in inertial confinement fusion capsules. The platform has been tested up to a convergence ratio of 4. An experimental campaign is underway to measure the growth of pre-imposed sinusoidal modulations of the capsule surface, as a function of wavelength, for a pair of ignition-relevant laser drives: a “low-foot” drive representative of what was fielded during the National Ignition Campaign (NIC) [Edwards et al., Phys. Plasmas 20, 070501 (2013)] and the new high-foot [Dittrich et al., Phys. Rev. Lett. 112, 055002 (2014); Park et al., Phys. Rev. Lett. 112, 055001 (2014)] pulse shape, for which the predicted instability growth is much lower. We present measurements of Legendre modes 30, 60, and 90 for the NIC-type, low-foot, drive, and modes 60 and 90 for the high-foot drive. The measured growth is consistent with model predictions, including much less growth for the high-foot drive, demonstrating the instability mitigation aspect of this new pulse shape. We present the design of the platform in detail and discuss the implications of the data it generates for the on-going ignition effort at NIF

ARCADE IMPLOSION CAUSED BY A FILAMENT ERUPTION IN A FLARE

Energy Technology Data Exchange (ETDEWEB)

Wang, Juntao; Simões, P. J. A.; Fletcher, L.; Hannah, I. G. [SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Thalmann, J. K. [Institute of Physics/IGAM, University of Graz, Universitätsplatz 5, A-8010 Graz (Austria); Hudson, H. S., E-mail: j.wang.4@research.gla.ac.uk [SSL/UC, Berkeley, CA (United States)

2016-12-20

Coronal implosions—the convergence motion of plasmas and entrained magnetic field in the corona due to a reduction in magnetic pressure—can help to locate and track sites of magnetic energy release or redistribution during solar flares and eruptions. We report here on the analysis of a well-observed implosion in the form of an arcade contraction associated with a filament eruption, during the C3.5 flare SOL2013-06-19T07:29. A sequence of events including the magnetic flux-rope instability and distortion, followed by a filament eruption and arcade implosion, lead us to conclude that the implosion arises from the transfer of magnetic energy from beneath the arcade as part of the global magnetic instability, rather than due to local magnetic energy dissipation in the flare. The observed net contraction of the imploding loops, which is found also in nonlinear force-free field extrapolations, reflects a permanent reduction of magnetic energy underneath the arcade. This event shows that, in addition to resulting in the expansion or eruption of an overlying field, flux-rope instability can also simultaneously implode an unopened field due to magnetic energy transfer. It demonstrates the “partial opening of the field” scenario, which is one of the ways in 3D to produce a magnetic eruption without violating the Aly–Sturrock hypothesis. In the framework of this observation, we also propose a unification of three main concepts for active region magnetic evolution, namely the metastable eruption model, the implosion conjecture, and the standard “CSHKP” flare model.

Posterior capsule opacification.

Science.gov (United States)

Wormstone, I Michael; Wang, Lixin; Liu, Christopher S C

2009-02-01

Posterior Capsule Opacification (PCO) is the most common complication of cataract surgery. At present the only means of treating cataract is by surgical intervention, and this initially restores high visual quality. Unfortunately, PCO develops in a significant proportion of patients to such an extent that a secondary loss of vision occurs. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens. The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. However, on the remaining anterior capsule, lens epithelial cells stubbornly reside despite enduring the rigours of surgical trauma. This resilient group of cells then begin to re-colonise the denuded regions of the anterior capsule, encroach onto the intraocular lens surface, occupy regions of the outer anterior capsule and most importantly of all begin to colonise the previously cell-free posterior capsule. Cells continue to divide, begin to cover the posterior capsule and can ultimately encroach on the visual axis resulting in changes to the matrix and cell organization that can give rise to light scatter. This review will describe the biological mechanisms driving PCO progression and discuss the influence of IOL design, surgical techniques and putative drug therapies in regulating the rate and severity of PCO.

Planar hydrodynamic instability computations and experiments with rugby-shaped hohlraums at the Omega laser

Energy Technology Data Exchange (ETDEWEB)

Vandenboomgaerde, M; Liberatore, S; Galmiche, D; Casner, A; Huser, G; Jadaud, J P; Villette, B [Commissariat a l' Energie Atomique, CEA/DAM-Ile de France, BP 12, 91680 Bruyeres-Le-Chatel (France)

2008-05-15

Implosion of inertial confinement fusion (ICF) capsule is very sensitive to the growth of sphericity perturbations. The control of the feeding of such perturbations and their transport ('feedthrough') through the ablator is a key point to reach ignition. Since 2002, experiments have been designed and performed on the Omega laser facility in order to study these phenomena in planar geometry. A new 'rugby shaped' hohlraum was used. We present experimental results and comparisons with numerical simulations.

Non-equilibrium between ions and electrons inside hot spots from National Ignition Facility experiments

OpenAIRE

Zhengfeng Fan; Yuanyuan Liu; Bin Liu; Chengxin Yu; Ke Lan; Jie Liu

2017-01-01

The non-equilibrium between ions and electrons in the hot spot can relax the ignition conditions in inertial confinement fusion [Fan et al., Phys. Plasmas 23, 010703 (2016)], and obvious ion-electron non-equilibrium could be observed by our simulations of high-foot implosions when the ion-electron relaxation is enlarged by a factor of 2. On the other hand, in many shots of high-foot implosions on the National Ignition Facility, the observed X-ray enhancement factors due to ablator mixing into...

Design of foil implosion system for Pioneer I experiments

International Nuclear Information System (INIS)

Erickson, D.J.; Caird, R.S.; Fowler, C.M.

1985-01-01

A foil implosion system is described that integrates an explosive flux-compression generator, a flat plate feed section with power conditioning switches, and a vacuum electrode region containing a cylindrical foil/plasma load. Power conditioning, obtained with an explosive-driven plasma compression opening switch and explosive-actuated closing switches, provides a submicrosecond multimegampere pulse for the implosion of an aluminum plasma. The flat plate section is configured for bidirectional feed to the coaxial vacuum electrodes. Important considerations in the design of the vacuum power flow region include gap failure, feed symmetry, and radial diagnostic access. The system presently accommodates a foil radius of 3 cm. Innovative foil insertion and clamping techniques are also described

Direct drive: Simulations and results from the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Radha, P. B., E-mail: rbah@lle.rochester.edu; Hohenberger, M.; Edgell, D. H.; Marozas, J. A.; Marshall, F. J.; Michel, D. T.; Rosenberg, M. J.; Seka, W.; Shvydky, A.; Boehly, T. R.; Collins, T. J. B.; Campbell, E. M.; Craxton, R. S.; Delettrez, J. A.; Froula, D. H.; Goncharov, V. N.; Hu, S. X.; Knauer, J. P.; McCrory, R. L.; McKenty, P. W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); and others

2016-05-15

Direct-drive implosion physics is being investigated at the National Ignition Facility. The primary goal of the experiments is twofold: to validate modeling related to implosion velocity and to estimate the magnitude of hot-electron preheat. Implosion experiments indicate that the energetics is well-modeled when cross-beam energy transfer (CBET) is included in the simulation and an overall multiplier to the CBET gain factor is employed; time-resolved scattered light and scattered-light spectra display the correct trends. Trajectories from backlit images are well modeled, although those from measured self-emission images indicate increased shell thickness and reduced shell density relative to simulations. Sensitivity analyses indicate that the most likely cause for the density reduction is nonuniformity growth seeded by laser imprint and not laser-energy coupling. Hot-electron preheat is at tolerable levels in the ongoing experiments, although it is expected to increase after the mitigation of CBET. Future work will include continued model validation, imprint measurements, and mitigation of CBET and hot-electron preheat.

Using high-intensity laser-generated energetic protons to radiograph directly driven implosions

International Nuclear Information System (INIS)

Zylstra, A. B.; Li, C. K.; Rinderknecht, H. G.; Seguin, F. H.; Petrasso, R. D.; Stoeckl, C.; Meyerhofer, D. D.; Nilson, P.; Sangster, T. C.; Le Pape, S.; Mackinnon, A.; Patel, P.

2012-01-01

The recent development of petawatt-class lasers with kilojoule-picosecond pulses, such as OMEGA EP [L. Waxer et al., Opt. Photonics News 16, 30 (2005)], provides a new diagnostic capability to study inertial-confinement-fusion (ICF) and high-energy-density (HED) plasmas. Specifically, petawatt OMEGA EP pulses have been used to backlight OMEGA implosions with energetic proton beams generated through the target normal sheath acceleration (TNSA) mechanism. This allows time-resolved studies of the mass distribution and electromagnetic field structures in ICF and HED plasmas. This principle has been previously demonstrated using Vulcan to backlight six-beam implosions [A. J. Mackinnon et al., Phys. Rev. Lett. 97, 045001 (2006)]. The TNSA proton backlighter offers better spatial and temporal resolution but poorer spatial uniformity and energy resolution than previous D 3 He fusion-based techniques [C. Li et al., Rev. Sci. Instrum. 77, 10E725 (2006)]. A target and the experimental design technique to mitigate potential problems in using TNSA backlighting to study full-energy implosions is discussed. The first proton radiographs of 60-beam spherical OMEGA implosions using the techniques discussed in this paper are presented. Sample radiographs and suggestions for troubleshooting failed radiography shots using TNSA backlighting are given, and future applications of this technique at OMEGA and the NIF are discussed.

Investigation of condensation implosion by changing configurations of water and steam inlets

International Nuclear Information System (INIS)

Seporaitis, Marijus; Pabarcius, Raimondas; Almenas, Kazys

2003-01-01

A previous paper (Seporaitis, 2002) presented experimental results, which showed that it is possible to induce condensation implosion events in a horizontal cylindrical pulser solely by varying the introduction rate of sub-cooled liquid. Interface disruption is triggered when an increasing liquid-vapor inter-face generates a growing condensation rate that leads to larger vapor flows. Vapor flow and condensation induced shear initiate surface waves and when these exceed a 'critical' growth rate complete interface disruption leading to a rapid condensation pulse. Although initial experimental success-generation of condensation implosion events in a controlled manner-was achieved it was determined that the range of the liquid introduction rate is fairly narrow. To avoid a high liquid heat up (negative factor for initiation of condensation implosion events) during it inducing into pulser and to expend range of the controlling variable the internal flow configurations in the further tests were used. The experimental studies presented in this paper have shown that trace amount of non-condensable gas have a larger effect on the initiation of a controlled condensation implosion event then was initially assumed. The influence of non-condensable gas is shown to be of an equivalent importance as the liquid side turbulence that is modulated by the rate of liquid introduction. (author)

Foot-pulse radiation drive necessary for ICF ignition capsule demonstrated on Z generator

International Nuclear Information System (INIS)

Sanford, T.W.L.; Olson, R.E.; Chandler, G.A.

1999-01-01

Implosion and ignition of an indirectly-driven ICF capsule operating near a Fermi-degenerate isentrope requires initial Planckian-radiation-drive temperatures of 70-to-90 eV to be present for a duration of 10-to-15 ns prior to the main drive pulse. Such capsules are being designed for high pulsed-power generators. This foot-pulse drive capability has been recently demonstrated in a NIF-sized (φ = 6-mm 1 = 7-mm), gold hohlraum, using a one-sided static-wall hohlraum geometry on the Z generator. The general arrangement utilized nested tungsten-wire arrays of radii (mass) 20 mm (2 mg) and 10 mm (1 mg) that had an axial length of approximately 10 mm. The arrays were driven by a peak current of approximately 21 MA and were made to implode on a 2-microm-thick Cu annulus (mass = 4.5 mg), which had a radius of 4 mm and was filled with a low-density CH foam, all centered about the z-axis. The gold hohlraum was mounted on axis and above the Cu/foam target. A 2.9-mm-radius axial hole between the top of the target and hohlraum permitted the x-rays generated from the implosion to enter the hohlraum. The radiation within the hohlraum was monitored by viewing the hohlraum through a 3-mm diameter hole on the lateral side of the hohlraum with a suite of diagnostics.The radiation entering the hohlraum was estimated by an additional suite of on-axis diagnostics, in a limited number of separate shots, when the hohlraum was not present. Additionally, the radiation generated outside the Cu annulus was monitored, for all shots, through a 3-mm diameter aperture located on the outside of the current return can. In the full paper, the characteristics of the radiation measured from these diagnostic sets, including the Planckian temperature of the hohlraum and radiation images, will be discussed as a function of the incident wire-array geometry (single vs nested array and array mass), target length (10, or 20 mm), annulus material (Cu, Au, or nothing), and CH-foam-fill density (10, 6, 2

Simulation analysis of the effects of an initial cone position and opening angle on a cone-guided implosion

Energy Technology Data Exchange (ETDEWEB)

Yanagawa, T. [Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan); Sakagami, H. [Fundamental Physics Simulation Division, National Institute for Fusion Science, Oroshi-cho, Toki, Gifu 509-5292 (Japan); Nagatomo, H. [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

2013-10-15

In inertial confinement fusion, the implosion process is important in forming a high-density plasma core. In the case of a fast ignition scheme using a cone-guided target, the fuel target is imploded with a cone inserted. This scheme is advantageous for efficiently heating the imploded fuel core; however, asymmetric implosion is essentially inevitable. Moreover, the effect of cone position and opening angle on implosion also becomes critical. Focusing on these problems, the effect of the asymmetric implosion, the initial position, and the opening angle on the compression rate of the fuel is investigated using a three-dimensional pure hydrodynamic code.

Vibration test report on the instrumented capsule for fuel irradiation test

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jeong Soo; Yoon, D. B.; Wu, J. S.; Oh, J. M.; Park, S. J.; Cho, M. S.; Kim, B. G.; Kang, Y. W

2003-01-01

The fluid-induced vibration level of instrumented capsule, which was manufactured for fuel irradiation test at the reactor core of HANARO, was investigated. For this purpose, the instrumented capsule was loaded at the OR site of the HANARO design verification test facility that could simulate identical flow condition as the HANARO core. Then, vibration signals of the instrumented capsule subjected to various flow conditions were measured by using vibration sensors. In time domain analysis, maximum amplitudes and RMS values of the measured acceleration and displacement signals were obtained. By using frequency domain analysis, frequency components of the fluid-induced vibration were analyzed. In addition, natural frequencies of the instrumented capsule were obtained by performing modal test. The frequency analysis results showed that the natural frequency components near 7.5Hz and 17.5Hz were dominant in the fluid-induced vibration signal. The maximum amplitude of the accelerations was measured as 12.04m/s{sup 2} that is within the allowable vibrational limit(18.99m/s{sup 2})of the reactor structure. Also, the maximum displacement amplitude was calculated as 0.191mm. Since these vibration levels are remarkably low, excessive vibration is not expected when the irradiation test of the instrumented capsule is performed at the HANARO core.

Electroplating Gold-Silver Alloys for Spherical Capsules for NIF Double-Shell Targets

Energy Technology Data Exchange (ETDEWEB)

Bhandarkar, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Horwood, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bunn, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stadermann, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-08-17

For Inertial Confinement Fusion (ICF) implosions, a design based on gradients of high and mid Z materials could potentially be more robust than single element capsule systems. To that end, gold and silver alloys were electroplated on 2.0 mm diameter surrogate brass spheres using a new flow–based pulsed plating method specifically designed to minimize surface roughness without reducing plating rates. The coatings were analyzed by scanning electron microscope (SEM) and white light interferometry for surface topography, and by energy dispersive x-ray spectroscopy (EDX) to determine near-surface gold and silver compositions. The alloy range attainable was 15 to 85 weight percent gold using 1:1 and 1:3 silver to gold ratio plating baths at applied potentials of -0.7 volts to -1.8 volts. This range was bounded by the open circuit potential of the system and hydrogen evolution, and in theory could be extended by using ionic liquids or aprotic solutions. Preliminary gradient trials proved constant composition alloy data could be translated to smooth gradient plating, albeit at higher gold compositions.

Implosion and staging systems for a Scyllac Fusion Test Reactor

International Nuclear Information System (INIS)

Gribble, R.F.; Linford, R.K.; Thomassen, K.I.

1976-01-01

The implosion heating and adiabatic compression processes will be separated in future theta pinch devices. The circuit to achieve the fast implosion heating and power crowbar (staging) for the Scyllac Fusion Test Reactor is described here. The plasma is very tightly coupled to the circuit and presents a varying inductive load. Computer-aided circuit designs which achieve a programmed magnetic field waveform are described. The field approximates a two-step waveform, on-off-on, which is ideal for achieving the large initial plasma radius needed for stability. The components for the circuits have been developed and are being tested in experiments at Los Alamos

Implosion and staging systems for a Scyllac fusion test reactor

International Nuclear Information System (INIS)

Gribble, R.F.; Linford, R.K.; Thomassen, K.I.

1975-01-01

The implosion heating and adiabatic compression processes will be separated in future theta pinch devices. The circuit to achieve the fast implosion heating and power crowbar (staging) for the Scyllac Fusion Test Reactor is described here. The plasma is very tightly coupled to the circuit and presents a varying inductive load. Computer-aided circuit designs which achieve a programmed magnetic field waveform are described. The field approximates a two-step waveform, on-off-on, which is ideal for achieving the large initial plasma radius needed for stability. The components for the circuits have been developed and are being tested in experiments at Los Alamos. (auth)

Experimental studies of the argon-puff Z-pinch implosion process

International Nuclear Information System (INIS)

Huang Xianbin; Yang Libing; Gu Yuanchao; Deng Jianjun; Zhou Rongguo; Zou Jie; Zhou Shaotong; Zhang Siqun; Chen Guanghua; Chang Lihua; Li Fengping; Ouyang Kai; Li Jun; Yang Liang; Wang Xiong; Zhang Zhaohui

2006-01-01

A preliminary experiment for studying the argon-puff Z-pinch implosion process has been performed on the Yang accelerator. The ten-frame nanosecond temporal and spatial gated camera, visible high-speed scanning camera, differential laser interferometer, X-ray time integration pinhole camera and X-ray power system have been used to investigated the evolution of the argon-puff Z-pinch. Some typical results of argon-puff Z-pinch during implosion and pinch phase, including the 'zipper' effect, necking phenomenon, sausage instability, temperature changes and the effect of load current rise time, are given and analyzed as examples, and some relevant conclusions are drawn. (authors)

3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets

Energy Technology Data Exchange (ETDEWEB)

Buice, E S; Alger, E T; Antipa, N A; Bhandarkar, S D; Biesiada, T A; Conder, A D; Dzenitis, E G; Flegel, M S; Hamza, A V; Heinbockel, C L; Horner, J; Johnson, M A; Kegelmeyer, L M; Meyer, J S; Montesanti, R C; Reynolds, J L; Taylor, J S; Wegner, P J

2011-02-18

This paper presents the development of a 3D surface mapping system used to measure the surface of a fusion target Capsule Fill-Tube Assembly (CFTA). The CFTA consists of a hollow Ge-doped plastic sphere, called a capsule, ranging in outer diameter between 2.2 mm and 2.6 mm and an attached 150 {micro}m diameter glass-core fill-tube that tapers down to a 10{micro} diameter at the capsule. The mapping system is an enabling technology to facilitate a quality assurance program and to archive 3D surface information of each capsule used in fusion ignition experiments that are currently being performed at the National Ignition Facility (NIF). The 3D Surface Mapping System is designed to locate and quantify surface features with a height of 50 nm and 300 nm in width or larger. Additionally, the system will be calibrated such that the 3D measured surface can be related to the capsule surface angular coordinate system to within 0.25 degree (1{sigma}), which corresponds to approximately 5 {micro}m linear error on the capsule surface.

3D Surface Mapping of Capsule Fill-Tube Assemblies used in Laser-Driven Fusion Targets

International Nuclear Information System (INIS)

Buice, E.S.; Alger, E.T.; Antipa, N.A.; Bhandarkar, S.D.; Biesiada, T.A.; Conder, A.D.; Dzenitis, E.G.; Flegel, M.S.; Hamza, A.V.; Heinbockel, C.L.; Horner, J.; Johnson, M.A.; Kegelmeyer, L.M.; Meyer, J.S.; Montesanti, R.C.; Reynolds, J.L.; Taylor, J.S.; Wegner, P.J.

2011-01-01

This paper presents the development of a 3D surface mapping system used to measure the surface of a fusion target Capsule Fill-Tube Assembly (CFTA). The CFTA consists of a hollow Ge-doped plastic sphere, called a capsule, ranging in outer diameter between 2.2 mm and 2.6 mm and an attached 150 (micro)m diameter glass-core fill-tube that tapers down to a 10(micro) diameter at the capsule. The mapping system is an enabling technology to facilitate a quality assurance program and to archive 3D surface information of each capsule used in fusion ignition experiments that are currently being performed at the National Ignition Facility (NIF). The 3D Surface Mapping System is designed to locate and quantify surface features with a height of 50 nm and 300 nm in width or larger. Additionally, the system will be calibrated such that the 3D measured surface can be related to the capsule surface angular coordinate system to within 0.25 degree (1σ), which corresponds to approximately 5 (micro)m linear error on the capsule surface.

Using high-intensity laser-generated energetic protons to radiograph directly driven implosions

Science.gov (United States)

Zylstra, A. B.; Li, C. K.; Rinderknecht, H. G.; Séguin, F. H.; Petrasso, R. D.; Stoeckl, C.; Meyerhofer, D. D.; Nilson, P.; Sangster, T. C.; Le Pape, S.; Mackinnon, A.; Patel, P.

2012-01-01

The recent development of petawatt-class lasers with kilojoule-picosecond pulses, such as OMEGA EP [L. Waxer et al., Opt. Photonics News 16, 30 (2005), 10.1364/OPN.16.7.000030], provides a new diagnostic capability to study inertial-confinement-fusion (ICF) and high-energy-density (HED) plasmas. Specifically, petawatt OMEGA EP pulses have been used to backlight OMEGA implosions with energetic proton beams generated through the target normal sheath acceleration (TNSA) mechanism. This allows time-resolved studies of the mass distribution and electromagnetic field structures in ICF and HED plasmas. This principle has been previously demonstrated using Vulcan to backlight six-beam implosions [A. J. Mackinnon et al., Phys. Rev. Lett. 97, 045001 (2006), 10.1103/PhysRevLett.97.045001]. The TNSA proton backlighter offers better spatial and temporal resolution but poorer spatial uniformity and energy resolution than previous D3He fusion-based techniques [C. Li et al., Rev. Sci. Instrum. 77, 10E725 (2006), 10.1063/1.2228252]. A target and the experimental design technique to mitigate potential problems in using TNSA backlighting to study full-energy implosions is discussed. The first proton radiographs of 60-beam spherical OMEGA implosions using the techniques discussed in this paper are presented. Sample radiographs and suggestions for troubleshooting failed radiography shots using TNSA backlighting are given, and future applications of this technique at OMEGA and the NIF are discussed.

Effects of food on a gastrically degraded drug: azithromycin fast-dissolving gelatin capsules and HPMC capsules.

Science.gov (United States)

Curatolo, William; Liu, Ping; Johnson, Barbara A; Hausberger, Angela; Quan, Ernest; Vendola, Thomas; Vatsaraj, Neha; Foulds, George; Vincent, John; Chandra, Richa

2011-07-01

Commercial azithromycin gelatin capsules (Zithromax®) are known to be bioequivalent to commercial azithromycin tablets (Zithromax®) when dosed in the fasted state. These capsules exhibit a reduced bioavailability when dosed in the fed state, while tablets do not. This gelatin capsule negative food effect was previously proposed to be due to slow and/or delayed capsule disintegration in the fed stomach, resulting in extended exposure of the drug to gastric acid, leading to degradation to des-cladinose-azithromycin (DCA). Azithromycin gelatin capsules were formulated with "superdisintegrants" to provide fast-dissolving capsules, and HPMC capsule shells were substituted for gelatin capsule shells, in an effort to eliminate the food effect. Healthy volunteers were dosed with these dosage forms under fasted and fed conditions; pharmacokinetics were evaluated. DCA pharmacokinetics were also evaluated for the HPMC capsule subjects. In vitro disintegration of azithromycin HPMC capsules in media containing food was evaluated and compared with commercial tablets and commercial gelatin capsules. When the two fast-dissolving capsule formulations were dosed to fed subjects, the azithromycin AUC was 38.9% and 52.1% lower than after fasted-state dosing. When HPMC capsules were dosed to fed subjects, the azithromycin AUC was 65.5% lower than after fasted-state dosing. For HPMC capsules, the absolute fasting-state to fed-state decrease in azithromycin AUC (on a molar basis) was similar to the increase in DCA AUC. In vitro capsule disintegration studies revealed extended disintegration times for commercial azithromycin gelatin capsules and HPMC capsules in media containing the liquid foods milk and Ensure®. Interaction of azithromycin gelatin and HPMC capsules with food results in slowed disintegration in vitro and decreased bioavailability in vivo. Concurrent measurement of serum azithromycin and the acid-degradation product DCA demonstrates that the loss of azithromycin

Waste Encapsulation and Storage Facility (WESF) Basis for Interim Operation (BIO)

International Nuclear Information System (INIS)

COVEY, L.I.

2000-01-01

The Waste Encapsulation and Storage Facility (WESF) is located in the 200 East Area adjacent to B Plant on the Hanford Site north of Richland, Washington. The current WESF mission is to receive and store the cesium and strontium capsules that were manufactured at WESF in a safe manner and in compliance with all applicable rules and regulations. The scope of WESF operations is currently limited to receipt, inspection, decontamination, storage, and surveillance of capsules in addition to facility maintenance activities. The capsules are expected to be stored at WESF until the year 2017, at which time they will have been transferred for ultimate disposition. The WESF facility was designed and constructed to process, encapsulate, and store the extracted long-lived radionuclides, 90 Sr and 137 Cs, from wastes generated during the chemical processing of defense fuel on the Hanford Site thus ensuring isolation of hazardous radioisotopes from the environment. The construction of WESF started in 1971 and was completed in 1973. Some of the 137 Cs capsules were leased by private irradiators or transferred to other programs. All leased capsules have been returned to WESF. Capsules transferred to other programs will not be returned except for the seven powder and pellet Type W overpacks already stored at WESF

Waste Encapsulation and Storage Facility (WESF) Basis for Interim Operation (BIO)

Energy Technology Data Exchange (ETDEWEB)

COVEY, L.I.

2000-11-28

The Waste Encapsulation and Storage Facility (WESF) is located in the 200 East Area adjacent to B Plant on the Hanford Site north of Richland, Washington. The current WESF mission is to receive and store the cesium and strontium capsules that were manufactured at WESF in a safe manner and in compliance with all applicable rules and regulations. The scope of WESF operations is currently limited to receipt, inspection, decontamination, storage, and surveillance of capsules in addition to facility maintenance activities. The capsules are expected to be stored at WESF until the year 2017, at which time they will have been transferred for ultimate disposition. The WESF facility was designed and constructed to process, encapsulate, and store the extracted long-lived radionuclides, {sup 90}Sr and {sup 137}Cs, from wastes generated during the chemical processing of defense fuel on the Hanford Site thus ensuring isolation of hazardous radioisotopes from the environment. The construction of WESF started in 1971 and was completed in 1973. Some of the {sup 137}Cs capsules were leased by private irradiators or transferred to other programs. All leased capsules have been returned to WESF. Capsules transferred to other programs will not be returned except for the seven powder and pellet Type W overpacks already stored at WESF.

Potential value of Cs-137 capsules

Energy Technology Data Exchange (ETDEWEB)

Bloomster, C.H.; Brown, D.R.; Bruno, G.A.; Hazelton, R.F.; Hendrickson, P.L.; Lezberg, A.J.; Tingey, G.L.; Wilfert, G.L.

1985-04-01

We determined the value of Cs-137 compared to Co-60 as a source for the irradiation of fruit (apples and cherries), pork and medical supplies. Cs-137, in the WESF capsule form, had a value of approximately $0.40/Ci as a substitute for Co-60 priced at approximately $1.00/Ci. The comparison was based on the available curies emitted from the surface of each capsule. We developed preliminary designs for fourteen irradiation facilities; seven were based on Co-60 and seven were based on Cs-137. These designs provided the basis for estimating capital and operating costs which, in turn, provided the basis for determining the value of Cs-137 relative to Co-60 in these applications. We evaluated the effect of the size of the irradiation facility on the value of Cs-137. The cost of irradiation is low compared to the value of the product. Irradiation of apples for disinfestation costs $.01 to .02 per pound. Irradiation for trichina-safe pork costs $.02 per pound. Irradiation of medical supplies for sterilization costs $.07 to .12 per pound. The cost of the irradiation source, either Co-60 or Cs-137, contributed only a minor amount to the total cost of irradiation, about 5% for the fruit and hog cases and about 20% for the medical supply cases. We analyzed the sensitivity of the irradiation costs and Cs-137 value to several key assumptions.

Potential value of Cs-137 capsules

International Nuclear Information System (INIS)

Bloomster, C.H.; Brown, D.R.; Bruno, G.A.; Hazelton, R.F.; Hendrickson, P.L.; Lezberg, A.J.; Tingey, G.L.; Wilfert, G.L.

1985-04-01

We determined the value of Cs-137 compared to Co-60 as a source for the irradiation of fruit (apples and cherries), pork and medical supplies. Cs-137, in the WESF capsule form, had a value of approximately $0.40/Ci as a substitute for Co-60 priced at approximately $1.00/Ci. The comparison was based on the available curies emitted from the surface of each capsule. We developed preliminary designs for fourteen irradiation facilities; seven were based on Co-60 and seven were based on Cs-137. These designs provided the basis for estimating capital and operating costs which, in turn, provided the basis for determining the value of Cs-137 relative to Co-60 in these applications. We evaluated the effect of the size of the irradiation facility on the value of Cs-137. The cost of irradiation is low compared to the value of the product. Irradiation of apples for disinfestation costs $.01 to .02 per pound. Irradiation for trichina-safe pork costs $.02 per pound. Irradiation of medical supplies for sterilization costs $.07 to .12 per pound. The cost of the irradiation source, either Co-60 or Cs-137, contributed only a minor amount to the total cost of irradiation, about 5% for the fruit and hog cases and about 20% for the medical supply cases. We analyzed the sensitivity of the irradiation costs and Cs-137 value to several key assumptions

In situ mechanical-radiation effects test capsule for simulating fusion material environments

International Nuclear Information System (INIS)

Christensen, K.E.; Bennett, G.A.; Sommer, W.F.

1981-01-01

Conditions of radiation and simultaneous cyclic stress on materials are inherent in advanced energy source designs such as inertially and magnetically confined controlled thermonuclear reactors. A test capsule capable of applying a cyclic stress to test specimens while they are being irradiated in the 800-MeV proton beam at the Clinton P. Anderson Los Alamos Meson Physics Facility has been developed. The design and performance of this device are discussed in this report. This machine has facilities for seven pairs of differential samples; one sample of a pair receives an applied cyclic stress and its companion in an identical flux will be the unstressed control. Control of the sample temperature and in situ monitoring of sample elongation and load are provided in the design. Results of an earlier experiment will be discussed, along with those of preliminary bench tests of the redesigned capsule

Summary of the first neutron image data collected at the National Ignition Facility

Directory of Open Access Journals (Sweden)

Grim Gary P.

2013-11-01

Full Text Available 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.

Defect-induced mix experiment for NIF

Directory of Open Access Journals (Sweden)

Schmitt M.J.

2013-11-01

Full Text Available The Defect Induced Mix Experiment (DIME-II will measure the implosion and mix characteristics of CH capsules filled with 5 atmospheres of DT by incorporating mid-Z dopant layers of Ge and Ga. This polar direct drive (PDD experiment also will demonstrate the filling of a CH capsule at target chamber center using a fill tube. Diagnostics for these experiments include areal x-ray backlighting to obtain early time images of the implosion trajectory and a multiple-monochromatic imager (MMI to collect spectrally-resolved images of the capsule dopant line emission near bangtime. The inclusion of two (or more thin dopant layers at separate depths within the capsule shell facilitates spatial correlation of mix between the layers and the hot gas core on a single shot. The dopant layers are typically 2 μm thick and contain dopant concentrations of 1.5%. Three dimensional Hydra simulations have been performed to assess the effects of PDD asymmetry on capsule performance.

Documentation associated with the WESF preparation for receiving 25 cesium capsules from the Applied Radiant Energy Corporation (ARECO)

Energy Technology Data Exchange (ETDEWEB)

Pawlak, M.W.

1996-10-21

The purpose of this report is to compile all documentation associated with facility preparation of WESF to receive 25 cesium capsules from ARECO. The WESF validated it`s preparedness by completing a facility preparedness review using a performance indicator checklist.

Moving finite element method for ICF target implosion

Science.gov (United States)

Furuta, J.; Kawata, S.; Niu, K.

1985-03-01

One dimensional hydrodynamic codes for the analysis of internal confinement fusion (ICF) target implosion which include various effects were developed, but most of them utilize the artificial viscosity (e.g., Von Neumann's viscosity) which cannot reveal accurately the shock waves. A gain of ICF target implosion is much due to the dissipation at the shock fronts, so it is necessary to express correctly the shock waves which are affected by the viscosity. The width of the shock waves is usually a few times as large as the length of mean free path, therefore the meshes for the shock waves must be set to about 10 to the 4th to 10 to the 5th power. It is a serious problem because of the computational memories or CPU time. In the moving finite element (MPE) method, both nodal amplitudes and nodal positions move continuously with time in such a way as to satisfy simultaneous ordinary differential equations (OPDs) which minimize partial differential equation (PDE) residuals.

Hydromagnetic Rayleigh endash Taylor instability in high-velocity gas-puff implosions

International Nuclear Information System (INIS)

Roderick, N.F.; Peterkin, R.E. Jr.; Hussey, T.W.; Spielman, R.B.; Douglas, M.R.; Deeney, C.

1998-01-01

Experiments using the Saturn pulsed power generator have produced high-velocity z-pinch plasma implosions with velocities over 100 cm/μs using both annular and uniform-fill gas injection initial conditions. Both types of implosion show evidence of the hydromagnetic Rayleigh endash Taylor instability with the uniform-fill plasmas producing a more spatially uniform pinch. Two-dimensional magnetohydrodynamic simulations including unsteady flow of gas from a nozzle into the diode region have been used to investigate these implosions. The instability develops from the nonuniform gas flow field that forms as the gas expands from the injection nozzle. Instability growth is limited to the narrow unstable region of the current sheath. For the annular puff the unstable region breaks through the inner edge of the annulus increasing nonlinear growth as mass ejected from the bubble regions is not replenished by accretion. This higher growth leads to bubble thinning and disruption producing greater nonuniformity at pinch for the annular puff. The uniform puff provides gas to replenish bubble mass loss until just before pinch resulting in less bubble thinning and a more uniform pinch. copyright 1998 American Institute of Physics

Analysis of staged Z-pinch implosion trajectories from experiments on Zebra

Science.gov (United States)

Ross, Mike P.; Conti, F.; Darling, T. W.; Ruskov, E.; Valenzuela, J.; Wessel, F. J.; Beg, F.; Narkis, J.; Rahman, H. U.

2017-10-01

The Staged Z-pinch plasma confinement concept relies on compressing an annular liner of high-Z plasma onto a target plasma column of deuterium fuel. The interface between the liner and target is stable against the Magneto-Rayleigh-Taylor Instability, which leads to effective fuel compression and makes the concept interesting as a potential fusion reactor. The liner initiates as a neutral gas puff, while the target plasma is a partially ionized (Zeff coaxial plasma gun. The Zebra pulsed power generator (1 MA peak current, 100 ns rise time) provides the discharge that ionizes the liner and drives the Z-pinch implosion. Diverse diagnostics observe the 100-300 km/s implosions including silicon diodes, photo-conducting detectors (PCDs), laser shadowgraphy, an XUV framing camera, and a visible streak camera. The imaging diagnostics track instabilities smaller than 0.1 mm, and Z-pinch diameters below 2.5 mm are seen at peak compression. This poster correlates the data from these diagnostics to elucidate implosion behavior dependencies on liner gas, liner pressure, target pressure, and applied, axial-magnetic field. Funded by the Advanced Research Projects Agency - Energy, DE-AR0000569.

Two-dimensional integrated Z-pinch ICF design simulations

International Nuclear Information System (INIS)

Lash, J.S.

1999-01-01

The dynamic hohlraum ICF concept for a Z-pinch driver utilizes the imploding wire array collision with a target to produce a radiation history suitable for driving an embedded inertial confinement fusion (ICF) capsule. This target may consist of various shaped layers of low-density foams or solid-density materials. The use of detailed radiation magneto-hydrodynamic (RMHD) modeling is required for understanding and designing these complex systems. Critical to producing credible simulations and designs is inclusion of the Rayleigh-Taylor unstable wire-array dynamics; the bubble and spike structure of the collapsing sheath may yield regions of low-opacity enhancing radiation loss as well as introduce non-uniformities in the capsule's radiation drive. Recent improvements in LASNEX have allowed significant progress to be made in the modeling of unstable z-pinch implosions. Combining this with the proven ICF capsule design capabilities of LASNEX, the authors now have the modeling tools to produce credible, fully-integrated ICF dynamic hohlraum simulations. They present detailed two-dimensional RMHD simulations of recent ICF dynamic hohlraum experiments on the Sandia Z-machine as well as design simulations for the next-generation Z-pinch facility and future high-yield facility

Two-dimensional integrated Z-pinch ICF design simulations

Energy Technology Data Exchange (ETDEWEB)

Lash, J.S.

1999-07-01

The dynamic hohlraum ICF concept for a Z-pinch driver utilizes the imploding wire array collision with a target to produce a radiation history suitable for driving an embedded inertial confinement fusion (ICF) capsule. This target may consist of various shaped layers of low-density foams or solid-density materials. The use of detailed radiation magneto-hydrodynamic (RMHD) modeling is required for understanding and designing these complex systems. Critical to producing credible simulations and designs is inclusion of the Rayleigh-Taylor unstable wire-array dynamics; the bubble and spike structure of the collapsing sheath may yield regions of low-opacity enhancing radiation loss as well as introduce non-uniformities in the capsule's radiation drive. Recent improvements in LASNEX have allowed significant progress to be made in the modeling of unstable z-pinch implosions. Combining this with the proven ICF capsule design capabilities of LASNEX, the authors now have the modeling tools to produce credible, fully-integrated ICF dynamic hohlraum simulations. They present detailed two-dimensional RMHD simulations of recent ICF dynamic hohlraum experiments on the Sandia Z-machine as well as design simulations for the next-generation Z-pinch facility and future high-yield facility.

The LLNL [Lawrence Livermore National Laboratory] ICF [Inertial Confinement Fusion] Program: Progress toward ignition in the Laboratory

International Nuclear Information System (INIS)

Storm, E.; Batha, S.H.; Bernat, T.P.; Bibeau, C.; Cable, M.D.; Caird, J.A.; Campbell, E.M.; Campbell, J.H.; Coleman, L.W.; Cook, R.C.; Correll, D.L.; Darrow, C.B.; Davis, J.I.; Drake, R.P.; Ehrlich, R.B.; Ellis, R.J.; Glendinning, S.G.; Haan, S.W.; Haendler, B.L.; Hatcher, C.W.; Hatchett, S.P.; Hermes, G.L.; Hunt, J.P.; Kania, D.R.; Kauffman, R.L.; Kilkenny, J.D.; Kornblum, H.N.; Kruer, W.L.; Kyrazis, D.T.; Lane, S.M.; Laumann, C.W.; Lerche, R.A.; Letts, S.A.; Lindl, J.D.; Lowdermilk, W.H.; Mauger, G.J.; Montgomery, D.S.; Munro, D.H.; Murray, J.R.; Phillion, D.W.; Powell, H.T.; Remington, B.R.; Ress, D.B.; Speck, D.R.; Suter, L.J.; Tietbohl, G.L.; Thiessen, A.R.; Trebes, J.E.; Trenholme, J.B.; Turner, R.E.; Upadhye, R.S.; Wallace, R.J.; Wiedwald, J.D.; Woodworth, J.G.; Young, P.M.; Ze, F.

1990-01-01

The Inertial Confinement Fusion (ICF) Program at the Lawrence Livermore National Laboratory (LLNL) has made substantial progress in target physics, target diagnostics, and laser science and technology. In each area, progress required the development of experimental techniques and computational modeling. The objectives of the target physics experiments in the Nova laser facility are to address and understand critical physics issues that determine the conditions required to achieve ignition and gain in an ICF capsule. The LLNL experimental program primarily addresses indirect-drive implosions, in which the capsule is driven by x rays produced by the interaction of the laser light with a high-Z plasma. Experiments address both the physics of generating the radiation environment in a laser-driven hohlraum and the physics associated with imploding ICF capsules to ignition and high-gain conditions in the absence of alpha deposition. Recent experiments and modeling have established much of the physics necessary to validate the basic concept of ignition and ICF target gain in the laboratory. The rapid progress made in the past several years, and in particular, recent results showing higher radiation drive temperatures and implosion velocities than previously obtained and assumed for high-gain target designs, has led LLNL to propose an upgrade of the Nova laser to 1.5 to 2 MJ (at 0.35 μm) to demonstrate ignition and energy gains of 10 to 20 -- the Nova Upgrade

Calibration of the time response functions of a quenched plastic scintillator for neutron time of flight

CERN Document Server

Chen, J B; Peng, H S; Tang, C H; Zhang, B H; Ding, Y K; Chen, M; Chen, H S; Li, C G; Wen, T S; Yu, R Z

2002-01-01

The time response functions of an ultrafast quenched plastic scintillation detector used to measure neutron time of flight spectra were calibrated by utilizing cosmic rays and implosion neutrons from DT-filled capsules at the Shenguang II laser facility. These sources could be regarded as delta function pulses due to their much narrower time widths than those of the time response functions of the detection system. The results showed that the detector responses to DT neutrons and to cosmic rays were 1.18 and 0.96 ns FWHM, respectively.

The colorimetric analysis of anti-tuberculosis fixed-dose combination tablets and capsules.

Science.gov (United States)

Ellard, G A

1999-11-01

The perceived need to demonstrate whether or not the actual amounts of rifampicin, isoniazid and pyrazinamide in fixed-dose combination tablets or capsules correspond to their stated drug contents. To adapt specific, robust and simple colorimetric methods that have been previously applied to measuring plasma and urinary rifampicin, isoniazid, pyrazinamide and ethambutol concentrations to estimate tablet and capsule drug contents. The methods were applied to the analysis of 14 commercially manufactured fixed-dose combinations: two capsule and three tablet formulations containing rifampicin and isoniazid; seven tablet formulations containing rifampicin, isoniazid and pyrazinamide; and two tablet formulations containing rifampicin, isoniazid, pyrazinamide and ethambutol. All the combined formulations contained near to their stated drug contents. Replicate analyses confirmed the excellent precision of the drug analyses. Such methods are not only rapid to perform but should be practical in many Third World situations with relatively modest laboratory facilities.

Cylindrical implosion to measure the radiative properties of high density and temperature plasmas

International Nuclear Information System (INIS)

Xu Yan; Rose, S.J.

2000-01-01

Cylindrical implosion is of great interest because of its excellent diagnostic access. The authors present one-dimensional numerical simulations to explore the plasma conditions that may be achieved. Combined with the numerical data, the development of Rayleigh-Taylor instabilities and Richtmyer-Meshkov instabilities in those targets are estimated. The authors found that it is possible to achieve a high density and temperature plasma with a relatively low temperature and density gradient using a cylindrical implosion directly-driven by a high-power laser

Status of the material capsule irradiation and the development of the new capsule technology in HANARO

International Nuclear Information System (INIS)

Choo, Kee-Nam; Kang, Young-Hwan; Choi, Myoung-Hwan; Cho, Man-Soon; Kim, Bong-Goo

2006-01-01

A material capsule system including a main capsule, fixing, control, cutting, and transport systems was developed for an irradiation test of non-fissile materials in HANARO. 14 irradiation capsules (12 instrumented and 2 non-instrumented capsules) have been designed, fabricated and successfully irradiated in the HANARO CT and IR test holes since 1995. The capsules were mainly designed for an irradiation of the RPV (Reactor Pressure Vessel), reactor core materials, and Zr-based alloys. Most capsules were made for KAERI material research projects, but 5 capsules were made as a part of national projects for the promotion of the HANARO utilization for universities. Based on the accumulated irradiation experience and the user's sophisticated requirements, development of new instrumented capsule technologies for a more precise control of the irradiation temperature and fluence of a specimen irrespective of the reactor operation has been performed in HANARO. (author)

Angular biasing in implicit Monte-Carlo

International Nuclear Information System (INIS)

Zimmerman, G.B.

1994-01-01

Calculations of indirect drive Inertial Confinement Fusion target experiments require an integrated approach in which laser irradiation and radiation transport in the hohlraum are solved simultaneously with the symmetry, implosion and burn of the fuel capsule. The Implicit Monte Carlo method has proved to be a valuable tool for the two dimensional radiation transport within the hohlraum, but the impact of statistical noise on the symmetric implosion of the small fuel capsule is difficult to overcome. We present an angular biasing technique in which an increased number of low weight photons are directed at the imploding capsule. For typical parameters this reduces the required computer time for an integrated calculation by a factor of 10. An additional factor of 5 can also be achieved by directing even smaller weight photons at the polar regions of the capsule where small mass zones are most sensitive to statistical noise

Charged--particle beam implosion of fusion targets

International Nuclear Information System (INIS)

Clauser, M.J.; Sweeney, M.A.

1975-01-01

This paper discusses the calculated behavior of fusion targets consisting of solid shells filled with DT gas, irradiated by high power electron or ion beams. The current required for breakeven with gold shells is 500 to 1000 MA, independent of target radius and nearly independent of beam voltage in the 1 / 2 to 1 MeV range. Above 1 MeV the breakeven current increases because of the increased bremsstrahlung production by the beam electrons. By using a diamond ablator and a gold pusher, the breakeven current is reduced to 220 MA. The ion current required for breakeven (about 10 MA of protons) is independent of proton voltage above 10 MeV with gold shell targets. Below 10 MeV the range of the proton becomes too short for efficient coupling, and the required current increases, but the power does not. Various aspects of the symmetry and stability of the implosion are discussed. One finds that the relatively long deposition lengths of electrons result in relatively small growths of the Rayleigh--Taylor instability during the acceleration of the pusher, resulting in a relatively stable implosion

Design options for reducing the impact of the fill-tube in ICF implosion experiments on the NIF

Science.gov (United States)

Weber, Christopher R.; Berzak Hopkins, L. F.; Casey, D. T.; Clark, D. S.; Hammel, B. A.; Le Pape, S.; Macphee, A.; Milovich, J.; Pickworth, L. A.; Robey, H. F.; Smalyuk, V. A.; Stadermann, M.; Felker, S. J.; Nikroo, A.; Thomas, C. A.; Crippen, J.; Rice, N.

2017-10-01

Inertial Confinement Fusion (ICF) capsules on the National Ignition Facility (NIF) are filled with thermonuclear fuel through a fill-tube. When the capsule implodes, perturbations caused by the fill-tube allow ablator material to mix into the hot spot and reduce fusion performance. This talk will explore several design options that attempt to reduce this damaging effect. Reducing the diameter of the fill-tube and its entrance hole is the obvious course and has been tested in experiments. Simulations also show sensitivity to the amount of glue holding the fill-tube to the capsule and suggest that careful control of this feature can limit the amount of injected mass. Finally, an off-axis fill-tube reduces the initial squirt of material into the fuel and may be a way of further optimizing this engineering feature. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

Fabrication of hybrid graphene oxide/polyelectrolyte capsules by means of layer-by-layer assembly on erythrocyte cell templates

Directory of Open Access Journals (Sweden)

Joseba Irigoyen

2015-12-01

Full Text Available A novel and facile method was developed to produce hybrid graphene oxide (GO–polyelectrolyte (PE capsules using erythrocyte cells as templates. The capsules are easily produced through the layer-by-layer technique using alternating polyelectrolyte layers and GO sheets. The amount of GO and therefore its coverage in the resulting capsules can be tuned by adjusting the concentration of the GO dispersion during the assembly. The capsules retain the approximate shape and size of the erythrocyte template after the latter is totally removed by oxidation with NaOCl in water. The PE/GO capsules maintain their integrity and can be placed or located on other surfaces such as in a device. When the capsules are dried in air, they collapse to form a film that is approximately twice the thickness of the capsule membrane. AFM images in the present study suggest a film thickness of approx. 30 nm for the capsules in the collapsed state implying a thickness of approx. 15 nm for the layers in the collapsed capsule membrane. The polyelectrolytes used in the present study were polyallylamine hydrochloride (PAH and polystyrenesulfonate sodium salt (PSS. Capsules where characterized by transmission electron microscopy (TEM, atomic force microscopy (AFM, dynamic light scattering (DLS and Raman microscopy, the constituent layers by zeta potential and GO by TEM, XRD, and Raman and FTIR spectroscopies.

LLE Review 97 (October-December 2003)

International Nuclear Information System (INIS)

Goncharov, V.N.

2004-01-01

This volume of the LLE Review, covering October-December 2003, features 'Direct-Drive Cryogenic Target Implosion Performance on OMEGA.' Layered and characterized cryogenic D2 capsules have been imploded using high-contrast pulse shapes on the 60-beam OMEGA laser at the Laboratory for Laser Energetics. These experiments measure the sensitivity of the direct-drive implosion performance to parameters such as the inner-ice-surface roughness, the adiabat of the fuel during the implosion, and the laser power balance

Analytical Model for the Probability Characteristics of a Crack Penetrating Capsules in Capsule-Based Self-Healing Cementitious Materials

Directory of Open Access Journals (Sweden)

Zhong LV

2017-08-01

Full Text Available Autonomous crack healing using pre-embedded capsules containing healing agent is becoming a promising approach to restore the strength of damaged structures. In addition to the material properties, the size and volume fraction of capsules influence crack healing in the matrix. Understanding the crack and capsule interaction is critical in the development and design of structures made of capsule-based self-healing materials. Continuing our previous study, in this contribution a more practical rupturing mode of capsules characterizing the rupturing manner of capsules fractured by cracks in cementitious materials is presented, i.e., penetrating mode. With the underlying assumption that a crack penetrating capsules undoubtedly leads to crack healing, geometrical probability theory is employed to develop the quantitative relationship between crack size and capsule size, capsule concentration in capsule-based self-healing virtual cementitious material. Moreover, an analytical expression of probability of a crack penetrating with randomly dispersed capsules is developed in two-dimensional material matrix setup. The influences of the induced rupturing modes of capsules embedded on the self-healing efficiency are analyzed. Much attention is paid to compare the penetrating probability and the hitting probability, in order to assist the designer to make a choice of the optimal rupturing modes of capsules embedded. The accuracy of results of the theoretical model is also compared with Monte-Carlo numerical analysis of crack interacting with capsules. It shows that the developed probability characteristics of a crack interaction with capsules for different rupturing modes is helpful to provide guidelines for designer working with capsule-based self-healing cementitious materials.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16888

A hybrid-drive nonisobaric-ignition scheme for inertial confinement fusion

Energy Technology Data Exchange (ETDEWEB)

He, X. T., E-mail: xthe@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009, Beijing 100094 (China); Center for Applied Physics and Technology, HEDPS, Peking University, Beijing 100871 (China); IFSA Collaborative Innovation Center of MoE, Shanghai Jiao-Tong University, Shanghai 200240 (China); Institute of Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Li, J. W.; Wang, L. F.; Liu, J.; Lan, K.; Ye, W. H. [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009, Beijing 100094 (China); Center for Applied Physics and Technology, HEDPS, Peking University, Beijing 100871 (China); IFSA Collaborative Innovation Center of MoE, Shanghai Jiao-Tong University, Shanghai 200240 (China); Fan, Z. F.; Wu, J. F. [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009, Beijing 100094 (China)

2016-08-15

A new hybrid-drive (HD) nonisobaric ignition scheme of inertial confinement fusion (ICF) is proposed, in which a HD pressure to drive implosion dynamics increases via increasing density rather than temperature in the conventional indirect drive (ID) and direct drive (DD) approaches. In this HD (combination of ID and DD) scheme, an assembled target of a spherical hohlraum and a layered deuterium-tritium capsule inside is used. The ID lasers first drive the shock to perform a spherical symmetry implosion and produce a large-scale corona plasma. Then, the DD lasers, whose critical surface in ID corona plasma is far from the radiation ablation front, drive a supersonic electron thermal wave, which slows down to a high-pressure electron compression wave, like a snowplow, piling up the corona plasma into high density and forming a HD pressurized plateau with a large width. The HD pressure is several times the conventional ID and DD ablation pressure and launches an enhanced precursor shock and a continuous compression wave, which give rise to the HD capsule implosion dynamics in a large implosion velocity. The hydrodynamic instabilities at imploding capsule interfaces are suppressed, and the continuous HD compression wave provides main pdV work large enough to hotspot, resulting in the HD nonisobaric ignition. The ignition condition and target design based on this scheme are given theoretically and by numerical simulations. It shows that the novel scheme can significantly suppress implosion asymmetry and hydrodynamic instabilities of current isobaric hotspot ignition design, and a high-gain ICF is promising.

X-ray continuum as a measure of pressure and fuel–shell mix in compressed isobaric hydrogen implosion cores

Energy Technology Data Exchange (ETDEWEB)

Epstein, R.; Goncharov, V. N.; Marshall, F. J. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Betti, R.; Nora, R.; Christopherson, A. R. [Fusion Science Center and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Golovkin, I. E.; MacFarlane, J. J. [Prism Computational Sciences, Madison, Wisconsin 53711 (United States)

2015-02-15

Pressure, by definition, characterizes the conditions within an isobaric implosion core at peak compression [Gus'kov et al., Nucl. Fusion 16, 957 (1976); Betti et al., Phys. Plasmas 8, 5257 (2001)] and is a key parameter in quantifying its near-ignition performance [Lawson, Proc. Phys. Soc. London, B 70, 6 (1957); Betti et al., Phys. Plasmas 17, 058102 (2010); Goncharov et al., Phys. Plasmas 21, 056315 (2014); and Glenzer et al., Phys. Plasmas 19, 056318 (2012)]. At high spectral energy, where the x-ray emission from an imploded hydrogen core is optically thin, the emissivity profile can be inferred from the spatially resolved core emission. This emissivity, which can be modeled accurately under hot-core conditions, is dependent almost entirely on the pressure when measured within a restricted spectral range matched to the temperature range anticipated for the emitting volume. In this way, the hot core pressure at the time of peak emission can be inferred from the measured free-free emissivity profile. The pressure and temperature dependences of the x-ray emissivity and the neutron-production rate explain a simple scaling of the total filtered x-ray emission as a constant power of the total neutron yield for implosions of targets of similar design over a broad range of shell implosion isentropes. This scaling behavior has been seen in implosion simulations and is confirmed by measurements of high-isentrope implosions [Sangster et al., Phys. Plasmas 20, 056317 (2013)] on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)]. Attributing the excess emission from less-stable, low-isentrope implosions, above the level expected from this neutron-yield scaling, to the higher emissivity of shell carbon mixed into the implosion's central hot spot, the hot-spot “fuel–shell” mix mass can be inferred.

X-ray continuum as a measure of pressure and fuel–shell mix in compressed isobaric hydrogen implosion cores

International Nuclear Information System (INIS)

Epstein, R.; Goncharov, V. N.; Marshall, F. J.; Betti, R.; Nora, R.; Christopherson, A. R.; Golovkin, I. E.; MacFarlane, J. J.

2015-01-01

Pressure, by definition, characterizes the conditions within an isobaric implosion core at peak compression [Gus'kov et al., Nucl. Fusion 16, 957 (1976); Betti et al., Phys. Plasmas 8, 5257 (2001)] and is a key parameter in quantifying its near-ignition performance [Lawson, Proc. Phys. Soc. London, B 70, 6 (1957); Betti et al., Phys. Plasmas 17, 058102 (2010); Goncharov et al., Phys. Plasmas 21, 056315 (2014); and Glenzer et al., Phys. Plasmas 19, 056318 (2012)]. At high spectral energy, where the x-ray emission from an imploded hydrogen core is optically thin, the emissivity profile can be inferred from the spatially resolved core emission. This emissivity, which can be modeled accurately under hot-core conditions, is dependent almost entirely on the pressure when measured within a restricted spectral range matched to the temperature range anticipated for the emitting volume. In this way, the hot core pressure at the time of peak emission can be inferred from the measured free-free emissivity profile. The pressure and temperature dependences of the x-ray emissivity and the neutron-production rate explain a simple scaling of the total filtered x-ray emission as a constant power of the total neutron yield for implosions of targets of similar design over a broad range of shell implosion isentropes. This scaling behavior has been seen in implosion simulations and is confirmed by measurements of high-isentrope implosions [Sangster et al., Phys. Plasmas 20, 056317 (2013)] on the OMEGA laser system [Boehly et al., Opt. Commun. 133, 495 (1997)]. Attributing the excess emission from less-stable, low-isentrope implosions, above the level expected from this neutron-yield scaling, to the higher emissivity of shell carbon mixed into the implosion's central hot spot, the hot-spot “fuel–shell” mix mass can be inferred

Polydopamine-coated capsules

Science.gov (United States)

White, Scott R.; Sottos, Nancy R.; Kang, Sen; Baginska, Marta B.

2018-04-17

One aspect of the invention is a polymer material comprising a capsule coated with PDA. In certain embodiments, the capsule encapsulates a functional agent. The encapsulated functional agent may be an indicating agent, healing agent, protecting agent, pharmaceutical drug, food additive, or a combination thereof.

Rayleigh-Taylor instability in the deceleration phase of spherical implosion experiments

International Nuclear Information System (INIS)

Smalyuk, V.A.; Delettrez, J.A.; Goncharov, V.N.; Marshall, F.J.; Meyerhofer, D.D.; Regan, S.P.; Sangster, T.C.; Town, R.P.J.; Yaakobi, B.

2002-01-01

The temporal evolution of inner-shell modulations, unstable during the deceleration phase of a laser-driven spherical implosion, has been measured through K-edge imaging [B. Yaakobi et al., Phys. Plasmas 7, 3727 (2000)] of shells with titanium-doped layers. The main study was based on the implosions of 1 mm diam, 20 μm thick shells filled with either 18 atm or 4 atm of D 3 He gas driven with 23 kJ, 1 ns square laser pulses on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. These targets have similar modulation levels at the beginning of the deceleration phase due to similar modulation growths in the acceleration phase, but different modulation growths throughout the deceleration phase due to different fill pressures (convergence ratios). At peak compression, the measured inner surface, areal-density nonuniformity σ rms levels were 23±5 % for more-stable 18 atm fill targets and 53±11 % for less-stable 4 atm fill targets. The inner-surface modulations grow throughout the deceleration phase due to Rayleigh-Taylor instability and Bell-Plesset convergence effects. The nonuniformity at peak compression is sensitive to the initial perturbation level as measured in implosions with different laser-smoothing conditions

Review of safety issues that pertain to the use of WESF cesium chloride capsules in an irradiator

International Nuclear Information System (INIS)

Tingey, G.L.; Wheelwright, E.J.; Lytle, J.M.

1984-07-01

Since the recovery of the fission product cesium-137 began in 1967, about 1500 capsules, each containing an average of about 50,000 curies of cesium chloride, have been produced. These capsules were designed to safely store this gamma-emitting fission product, but they are now considered to be a valuable source for irradiators. The capsules were designed to have a large margin of safety in their mechanical properties. Impact, percussion, and thermal tests have been conducted that demonstrate their ability to meet anticipated licensing requirements. Although this document is not intended to develop or evaluate accident scenarios, an examination of the effects of heating a capsule to 800 0 C for up to 90 min was completed. At 800 0 C, the salt volume would be expected to exceed the initial capsule volume in a few (up to 1/3) of the WESF capsules. Under these conditions, the inner capsule would expand to accommodate the salt volume and the gas pressure. The strength and ductility of the capsule are more than adequate to permit this expansion with a safety margin of at least a factor of three. Capsules have now been stored in the WESF pool for 10 years, and 15 capsules have been used in the Sandia Irradiator for Dried Sewage Solids facility for nearly 5 years without any capsule failure. This experience, along with available laboratory and production data, gives reasonable assurance that the capsules can be safely used in properly designed commercial irradiators. This is especially the case when one considers current and future evaluation programs designed to assess the long-term effects of corrosion and mechanical properties degradation

Computational modeling of plasma-flow switched foil implosions

International Nuclear Information System (INIS)

Lindemuth, I.R.

1985-01-01

A ''plasma-flow'', or ''commutator'', switch has been proposed as a means of achieving high dI/dt in a radially imploding metallic foil plasma. In this concept, an axially moving foil provides the initial coaxial gun discharge path for the prime power source and provides and ''integral'' inductive storage of magnetic energy. As the axially moving foil reaches the end of the coaxial gun, a radially imploding load foil is switched into the circuit. The authors have begun two-dimensional computer modeling of the two-foil implosion system. They use a magnetohydrodynamic (MHD) model which includes tabulated state and transport properties of the metallic foil material. Moving numerical grids are used to achieve adequate resolution of the moving foils. A variety of radiation models are used to compute the radiation generated when the imploding load foil converges on axis. These computations are attempting to examine the interaction of the switching foil with the load foil. In particular, they examine the relationship between foil placement and implosion quality

Implosive Thermal Plasma Source for Energy Conversion

Czech Academy of Sciences Publication Activity Database

Šonský, Jiří; Tesař, Václav; Gruber, Jan; Mašláni, Alan

2017-01-01

Roč. 4, č. 1 (2017), s. 87-90 ISSN 2336-2626 Institutional support: RVO:61388998 ; RVO:61389021 Keywords : implosion * thermal plasma * detonation wave Subject RIV: BL - Plasma and Gas Discharge Physics; BL - Plasma and Gas Discharge Physics (UFP-V) OBOR OECD: Fluids and plasma physics (including surface physics); Fluids and plasma physics (including surface physics) (UFP-V) https://ppt.fel.cvut.cz/ppt2017.html#number1

Investigation on shortening fabrication process of instrumented irradiation capsule of JMTR

International Nuclear Information System (INIS)

Nagata, Hiroshi; Inoue, Shuichi; Yamaura, Takayuki; Tsuchiya, Kunihiko; Nagao, Yoshiharu

2013-06-01

Refurbishment of The Japan Materials Testing Reactor (JMTR) was completed in FY2010. For damage caused by the 2011 off the Pacific coast of Tohoku Earthquake, the repair of facilities was completed in October 2012. Currently, the JMTR is in preparation for restart. Irradiation tests for LWRs safety research, science and technologies and production of RI for medical diagnosis medicine, etc. are expected after the JMTR restart. On the other hand, aiming at the attractive irradiation testing reactor, the usability improvement has been discussed. As a part of the usability improvement, shortening of turnaround time to get irradiation results from an application for irradiation use was discussed focusing on the fabrication process of irradiation capsules, where the fabrication process was analyzed and reviewed by referring a trial fabrication of the mockup capsule. As a result, it was found that the turnaround time can be shortened 2 months from fabrication period of 6 months with communize of irradiation capsule parts, application of ready-made instrumentation including the sheath heater, reconsideration of inspection process, etc. (author)

Systematic Versus Semantic Desensitization and Implosive Therapy: A Comparative Study

Science.gov (United States)

Hekmat, Hamid

1973-01-01

In this study, both the semantic and systematic desensitization methods were found to be significantly more effective than the implosive therapy and the control treatments in the modification of phobic behavior among the college student population. (Author)

Fast ignition upon the implosion of a thin shell onto a precompressed deuterium-tritium ball

Science.gov (United States)

Gus'kov, S. Yu.; Zmitrenko, N. V.

2012-11-01

Fast ignition of a precompressed inertial confinement fusion (ICF) target by a hydrodynamic material flux is investigated. A model system of hydrodynamic objects consisting of a central deuterium-tritium (DT) ball and a concentric two-layer shell separated by a vacuum gap is analyzed. The outer layer of the shell is an ablator, while the inner layer consists of DT ice. The igniting hydrodynamic flux forms as a result of laser-driven acceleration and compression of the shell toward the system center. A series of one-dimensional numerical simulations of the shell implosion, the collision of the shell with the DT ball, and the generation and propagation of thermonuclear burn waves in both parts of the system are performed. Analytic models are developed that describe the implosion of a thin shell onto a central homogeneous ball of arbitrary radius and density and the initiation and propagation of a thermonuclear burn wave induced by such an implosion. Application of the solution of a model problem to analyzing the implosion of a segment of a spherical shell in a conical channel indicates the possibility of fast ignition of a spherical ICF target from a conical target driven by a laser pulse with an energy of 500-700 kJ.

Design and manufacturing of instrumented capsule (02F-06K/02F-11K) for nuclear fuel irradiation test in HANARO

International Nuclear Information System (INIS)

Kim, Bong Goo; Kang, Y. H.; Cho, M. S.; Sohn, J. M.; Choo, K. N.; Kim, D. S.; Oh, J. M.; Shin, Y.T.; Park, S.J.; Kim, Y. J.; Seo, C.G.; Ryu, J.S.; Cho, Y. G.

2003-02-01

To measure the characteristics of nuclear fuel during irradiation test, it is necessary to develop the instrumented capsule for the nuclear fuel irradiation test. Then considering the requirements for the nuclear fuel irradiation test and the compatibility with OR test hole in HANARO as well as the requirements for HANARO operation and related equipments, the instrumented capsule for the nuclear fuel irradiation test was designed and successfully manufactured. The structural integrity of the capsule design was verified by performing nuclear physics, structural and thermal analyses. And, not only out-of-pile tests such as pressure drop test, vibration test, endurance test, were performed in HANARO design verification test facility, but the mechanical and hydraulic safety of the capsule and the compatibility of the capsule with HANARO was verified

Waste Encapsulation and Storage Facility interim operational safety requirements

CERN Document Server

Covey, L I

2000-01-01

The Interim Operational Safety Requirements (IOSRs) for the Waste Encapsulation and Storage Facility (WESF) define acceptable conditions, safe boundaries, bases thereof, and management or administrative controls required to ensure safe operation during receipt and inspection of cesium and strontium capsules from private irradiators; decontamination of the capsules and equipment; surveillance of the stored capsules; and maintenance activities. Controls required for public safety, significant defense-in-depth, significant worker safety, and for maintaining radiological consequences below risk evaluation guidelines (EGs) are included.

Hohlraum designs for high velocity implosions on NIF