An antiproton driver for ICF propulsion

NASA Technical Reports Server (NTRS)

Chiang, Pi-Ren; Lewis, R. A.; Smith, G. A.; Gazze, C.; Higman, K.; Newton, R.; Chiaverini, M.; Dailey, J.; Surratt, M.; Werthman, W. Lance

1993-01-01

Inertial confinement fusion (ICF) utilizing an anitprotoncatalyzed target is discussed as a possible source of propulsion for rapid interplanetary manned space missions. The relevant compression, ignition, and thrust mechanisms are presented. Progress on an experiment presently in progress at the Phillips Laboratory, Kirtland AFB, NM to demonstrate proof-of-principle is reviewed.

Inertial Confinement Fusion Quarterly Report: April--June 1993. Volume 3, Number 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacGowan, B.J.; Kotowski, M.; Schleich, D.

1993-11-01

This issue of the ICF Quarterly contains six articles describing recent advances in Lawrence Livermore National Laboratory`s inertial confinement fusion (ICF) program. The current emphasis of the ICF program is in support of DOE`s National Ignition Facility (NIF) initiative for demonstrating ignition and gain with a 1-2 MJ glass laser. The articles describe recent Nova experiments and investigations tailored towards enhancing understanding of the key physics and technological issues for the NIF. Titles of the articles are: development of large-aperture KDP crystals; inner-shell photo-ionized X-ray lasers; X-ray radiographic measurements of radiation-driven shock and interface motion in solid density materials; themore » role of nodule defects in laser-induced damage of multilayer optical coatings; techniques for Mbar to near-Gbar equation-of-state measurements with the Nova laser; parametric instabilities and laser-beam smoothing.« less

Computer modeling and simulation in inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCrory, R.L.; Verdon, C.P.

1989-03-01

The complex hydrodynamic and transport processes associated with the implosion of an inertial confinement fusion (ICF) pellet place considerable demands on numerical simulation programs. Processes associated with implosion can usually be described using relatively simple models, but their complex interplay requires that programs model most of the relevant physical phenomena accurately. Most hydrodynamic codes used in ICF incorporate a one-fluid, two-temperature model. Electrons and ions are assumed to flow as one fluid (no charge separation). Due to the relatively weak coupling between the ions and electrons, each species is treated separately in terms of its temperature. In this paper wemore » describe some of the major components associated with an ICF hydrodynamics simulation code. To serve as an example we draw heavily on a two-dimensional Lagrangian hydrodynamic code (ORCHID) written at the University of Rochester's Laboratory for Laser Energetics. 46 refs., 19 figs., 1 tab.« less

FY14 LLNL OMEGA Experimental Programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heeter, R. F.; Fournier, K. B.; Baker, K.

In FY14, LLNL’s High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted several campaigns on the OMEGA laser system and on the EP laser system, as well as campaigns that used the OMEGA and EP beams jointly. Overall these LLNL programs led 324 target shots in FY14, with 246 shots using just the OMEGA laser system, 62 shots using just the EP laser system, and 16 Joint shots using Omega and EP together. Approximately 31% of the total number of shots (62 OMEGA shots, 42 EP shots) shots supported the Indirect Drive Inertial Confinement Fusion Campaign (ICF-ID).more » The remaining 69% (200 OMEGA shots and 36 EP shots, including the 16 Joint shots) were dedicated to experiments for High- Energy-Density Physics (HED). Highlights of the various HED and ICF campaigns are summarized in the following reports.« less

FY15 LLNL OMEGA Experimental Programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heeter, R. F.; Baker, K. L.; Barrios, M. A.

In FY15, LLNL’s High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted several campaigns on the OMEGA laser system and on the EP laser system, as well as campaigns that used the OMEGA and EP beams jointly. Overall these LLNL programs led 468 target shots in FY15, with 315 shots using just the OMEGA laser system, 145 shots using just the EP laser system, and 8 Joint shots using Omega and EP together. Approximately 25% of the total number of shots (56 OMEGA shots and 67 EP shots, including the 8 Joint shots) supported the Indirect Drivemore » Inertial Confinement Fusion Campaign (ICF-ID). The remaining 75% (267 OMEGA shots and 86 EP shots) were dedicated to experiments for High-Energy-Density Physics (HED). Highlights of the various HED and ICF campaigns are summarized in the following reports.« less

Hugoniot equation of state of Si-doped glow discharge polymer and scaling to other plastic ablators

NASA Astrophysics Data System (ADS)

Huser, G.; Ozaki, N.; Colin-Lalu, P.; Recoules, V.; Sano, T.; Sakawa, Y.; Miyanishi, K.; Kodama, R.

2018-05-01

Pressure, density, and temperature were measured along the principal Hugoniot of the Si-doped Glow Discharge Polymer used in Inertial Confinement Fusion (ICF) capsules up to 5 Mbar, covering conditions beyond the first shock in a full-scale Inertial Confinement Fusion (ICF) capsule. The experiments were performed using the GEKKOXII laser at the Institute of Laser Engineering at Osaka University in Japan. Results are in good agreement with predictions obtained from ab initio Hugoniot calculations, but softer than the quotidian equation of state average atom model. Ab initio calculations show that dissociation of carbon bonds need to be taken into account in order to explain Hugoniot compressibility.

The Nova Upgrade Facility for ICF ignition and gain

NASA Astrophysics Data System (ADS)

Lowdermilk, W. H.; Campbell, E. M.; Hunt, J. T.; Murray, J. R.; Storm, E.; Tobin, M. T.; Trenholme, J. B.

1992-01-01

Research on Inertial Confinement Fusion (ICF) is motivated by its potential defense and civilian applications, including ultimately the generation of electric power. The U.S. ICF Program was reviewed recently by the National Academy of Science (NAS) and the Fusion Policy Advisory Committee (FPAC). Both committees issued final reports in 1991 which recommended that first priority in the ICF program be placed on demonstrating fusion ignition and modest gain (G less than 10). The U.S. Department of Energy and Lawrence Livermore National Laboratory (LLNL) have proposed an upgrade of the existing Nova Laser Facility at LLNL to accomplish these goals. Both the NAS and FPAC have endorsed the upgrade of Nova as the optimal path to achieving ignition and gain. Results from Nova Upgrade Experiments will be used to define requirements for driver and target technology both for future high-yield military applications, such as the Laboratory Microfusion Facility (LMF) proposed by the Department of Energy, and for high-gain energy applications leading to an ICF engineering test facility. The central role and modifications which Nova Upgrade would play in the national ICF strategy are described.

The potential of imposed magnetic fields for enhancing ignition probability and fusion energy yield in indirect-drive inertial confinement fusion

NASA Astrophysics Data System (ADS)

Perkins, L. J.; Ho, D. D.-M.; Logan, B. G.; Zimmerman, G. B.; Rhodes, M. A.; Strozzi, D. J.; Blackfield, D. T.; Hawkins, S. A.

2017-06-01

We examine the potential that imposed magnetic fields of tens of Tesla that increase to greater than 10 kT (100 MGauss) under implosion compression may relax the conditions required for ignition and propagating burn in indirect-drive inertial confinement fusion (ICF) targets. This may allow the attainment of ignition, or at least significant fusion energy yields, in presently performing ICF targets on the National Ignition Facility (NIF) that today are sub-marginal for thermonuclear burn through adverse hydrodynamic conditions at stagnation [Doeppner et al., Phys. Rev. Lett. 115, 055001 (2015)]. Results of detailed two-dimensional radiation-hydrodynamic-burn simulations applied to NIF capsule implosions with low-mode shape perturbations and residual kinetic energy loss indicate that such compressed fields may increase the probability for ignition through range reduction of fusion alpha particles, suppression of electron heat conduction, and potential stabilization of higher-mode Rayleigh-Taylor instabilities. Optimum initial applied fields are found to be around 50 T. Given that the full plasma structure at capsule stagnation may be governed by three-dimensional resistive magneto-hydrodynamics, the formation of closed magnetic field lines might further augment ignition prospects. Experiments are now required to further assess the potential of applied magnetic fields to ICF ignition and burn on NIF.

Addressing Common Technical challenges in Inertial Confinement Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haynes, Donald A.

2016-09-22

The implosion phase for Inertial Confinement Fusion (ICF) occurs from initiation of the drive until just before stagnation. Evolution of the shell and fusion fuel during the implosion phase is affected by the initial conditions of the target, the drive history. Poor performing implosions are a result of the behavior that occurs during the implosion phase such as low mode asymmetries, mixing of the ablator into the fuel, and the hydrodynamic evolution of initial target features and defects such as the shell mounting hardware. The ultimate results of these effects can only be measured at stagnation. However, studying the implosionmore » phase can be effective for understanding and mitigating these effects and for of ultimately improving the performance of ICF implosions. As the ICF program moves towards the 2020 milestone to “determine the efficacy of ignition”, it will be important to understand the physics that occurs during the implosion phase. This will require both focused and integrated experiments. Focused experiments will provide the understanding and the evidence needed to support any determination concerning the efficacy of ignition.« less

Spallation as a dominant source of pusher-fuel and hot-spot mix in inertial confinement fusion capsules

DOE PAGES

Orth, Charles D.

2016-02-23

We suggest that a potentially dominant but previously neglected source of pusher-fuel and hot-spot “mix” may have been the main degradation mechanism for fusion energy yields of modern inertial confinement fusion (ICF) capsules designed and fielded to achieve high yields — not hydrodynamic instabilities. This potentially dominant mix source is the spallation of small chunks or “grains” of pusher material into the fuel regions whenever (1) the solid material adjacent to the fuel changes its phase by nucleation, and (2) this solid material spalls under shock loading and sudden decompression. Finally, we describe this mix mechanism, support it with simulationsmore » and experimental evidence, and explain how to eliminate it and thereby allow higher yields for ICF capsules and possibly ignition at the National Ignition Facility.« less

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

NASA Astrophysics Data System (ADS)

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 been briefly described, several of which are novel.

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

PubMed

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.

Generalized Lawson Criteria for Inertial Confinement Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tipton, Robert E.

2015-08-27

The Lawson Criterion was proposed by John D. Lawson in 1955 as a general measure of the conditions necessary for a magnetic fusion device to reach thermonuclear ignition. Over the years, similar ignition criteria have been proposed which would be suitable for Inertial Confinement Fusion (ICF) designs. This paper will compare and contrast several ICF ignition criteria based on Lawson’s original ideas. Both analytical and numerical results will be presented which will demonstrate that although the various criteria differ in some details, they are closely related and perform similarly as ignition criteria. A simple approximation will also be presented whichmore » allows the inference of each ignition parameter directly from the measured data taken on most shots fired at the National Ignition Facility (NIF) with a minimum reliance on computer simulations. Evidence will be presented which indicates that the experimentally inferred ignition parameters on the best NIF shots are very close to the ignition threshold.« less

Effects of magnetization on fusion product trapping and secondary neutron spectraa)

NASA Astrophysics Data System (ADS)

Knapp, P. F.; Schmit, P. F.; Hansen, S. B.; Gomez, M. R.; Hahn, K. D.; Sinars, D. B.; Peterson, K. J.; Slutz, S. A.; Sefkow, A. B.; Awe, T. J.; Harding, E.; Jennings, C. A.; Desjarlais, M. P.; Chandler, G. A.; Cooper, G. W.; Cuneo, M. E.; Geissel, M.; Harvey-Thompson, A. J.; Porter, J. L.; Rochau, G. A.; Rovang, D. C.; Ruiz, C. L.; Savage, M. E.; Smith, I. C.; Stygar, W. A.; Herrmann, M. C.

2015-05-01

By magnetizing the fusion fuel in inertial confinement fusion (ICF) systems, the required stagnation pressure and density can be relaxed dramatically. This happens because the magnetic field insulates the hot fuel from the cold pusher and traps the charged fusion burn products. This trapping allows the burn products to deposit their energy in the fuel, facilitating plasma self-heating. Here, we report on a comprehensive theory of this trapping in a cylindrical DD plasma magnetized with a purely axial magnetic field. Using this theory, we are able to show that the secondary fusion reactions can be used to infer the magnetic field-radius product, BR, during fusion burn. This parameter, not ρR, is the primary confinement parameter in magnetized ICF. Using this method, we analyze data from recent Magnetized Liner Inertial Fusion experiments conducted on the Z machine at Sandia National Laboratories. We show that in these experiments BR ≈ 0.34(+0.14/-0.06) MG . cm, a ˜ 14× increase in BR from the initial value, and confirming that the DD-fusion tritons are magnetized at stagnation. This is the first experimental verification of charged burn product magnetization facilitated by compression of an initial seed magnetic flux.

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

NASA Astrophysics Data System (ADS)

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.

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

PubMed

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

2016-12-09

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D_{2} and DT layer inertial confinement fusion (ICF) implosions that can access a low-to-moderate hot-spot convergence ratio (1230) 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.

Progress In Magnetized Target Fusion Driven by Plasma Liners

NASA Technical Reports Server (NTRS)

Thio, Francis Y. C.; Kirkpatrick, Ronald C.; Knapp, Charles E.; Cassibry, Jason; Eskridge, Richard; Lee, Michael; Smith, James; Martin, Adam; Wu, S. T.; Schmidt, George;

Block Ignition Inertial Confinement Fusion (ICF) with Condensed Matter Cluster Type Targets for p-B11 Powered Space Propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, George H.; Hora, H.; Badziak, J.

The use of laser-driven Inertial Confinement Fusion (ICF) for space propulsion has been the subject of several earlier conceptual design studies, (see: Orth, 1998; and other references therein). However, these studies were based on older ICF technology using either 'direct' or 'in-direct x-ray driven' type target irradiation. Important new directions have opened for laser ICF in recent years following the development of 'chirped' lasers capable of ultra short pulses with powers of TW up to few PW which leads to the concept of 'fast ignition (FI)' to achieve higher energy gains from target implosions. In a recent publication the authorsmore » showed that use of a modified type of FI, termed 'block ignition' (Miley et al., 2008), could meet many of the requirements anticipated (but not then available) by the designs of the Vehicle for Interplanetary Space Transport Applications (VISTA) ICF fusion propulsion ship (Orth, 2008) for deep space missions. Subsequently the first author devised and presented concepts for imbedding high density condensed matter 'clusters' of deuterium into the target to obtain ultra high local fusion reaction rates (Miley, 2008). Such rates are possible due to the high density of the clusters (over an order of magnitude above cryogenic deuterium). Once compressed by the implosion, the yet higher density gives an ultra high reaction rate over the cluster volume since the fusion rate is proportional to the square of the fuel density. Most recently, a new discovery discussed here indicates that the target matrix could be composed of B{sup 11} with proton clusters imbedded. This then makes p-B{sup 11} fusion practical, assuming all of the physics issues such as stability of the clusters during compression are resolved. Indeed, p-B{sup 11} power is ideal for fusion propulsion since it has a minimum of unwanted side products while giving most of the reaction energy to energetic alpha particles which can be directed into an exhaust (propulsion) nozzle. Power plants using p-B{sup 11} have been discussed for such applications before, but prior designs face formidable physics/technology issues, largely overcome with the present approach.« less

Fusion yield rate recovery by escaping hot-spot fast ions in the neighboring fuel layer

NASA Astrophysics Data System (ADS)

Tang, Xian-Zhu; McDevitt, C. J.; Guo, Zehua; Berk, H. L.

2014-02-01

Free-streaming loss by fast ions can deplete the tail population in the hot spot of an inertial confinement fusion (ICF) target. Escaping fast ions in the neighboring fuel layer of a cryogenic target can produce a surplus of fast ions locally. In contrast to the Knudsen layer effect that reduces hot-spot fusion reactivity due to tail ion depletion, the inverse Knudsen layer effect increases fusion reactivity in the neighboring fuel layer. In the case of a burning ICF target in the presence of significant hydrodynamic mix which aggravates the Knudsen layer effect, the yield recovery largely compensates for the yield reduction. For mix-dominated sub-ignition targets, the yield reduction is the dominant process.

Energy-resolved neutron imaging for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Moran, M. J.; Haan, S. W.; Hatchett, S. P.; Izumi, N.; Koch, J. A.; Lerche, R. A.; Phillips, T. W.

2003-03-01

The success of the National Ignition Facility program will depend on diagnostic measurements which study the performance of inertial confinement fusion (ICF) experiments. Neutron yield, fusion-burn time history, and images are examples of important diagnostics. Neutron and x-ray images will record the geometries of compressed targets during the fusion-burn process. Such images provide a critical test of the accuracy of numerical modeling of ICF experiments. They also can provide valuable information in cases where experiments produce unexpected results. Although x-ray and neutron images provide similar data, they do have significant differences. X-ray images represent the distribution of high-temperature regions where fusion occurs, while neutron images directly reveal the spatial distribution of fusion-neutron emission. X-ray imaging has the advantage of a relatively straightforward path to the imaging system design. Neutron imaging, by using energy-resolved detection, offers the intriguing advantage of being able to provide independent images of burning and nonburning regions of the nuclear fuel. The usefulness of energy-resolved neutron imaging depends on both the information content of the data and on the quality of the data that can be recorded. The information content will relate to the characteristic neutron spectra that are associated with emission from different regions of the source. Numerical modeling of ICF fusion burn will be required to interpret the corresponding energy-dependent images. The exercise will be useful only if the images can be recorded with sufficient definition to reveal the spatial and energy-dependent features of interest. Several options are being evaluated with respect to the feasibility of providing the desired simultaneous spatial and energy resolution.

High-Energy-Density-Physics Studies for Inertial Confinement Fusion Applications

NASA Astrophysics Data System (ADS)

Hu, S. X.

2017-10-01

Accurate knowledge of the static, transport, and optical properties of high-energy-density (HED) plasmas is essential for reliably designing and understanding inertial confinement fusion (ICF) implosions. In the warm-dense-matter regime routinely accessed by low-adiabat ICF implosions, many-body strong-coupling and quantum electron degeneracy effects play an important role in determining plasma properties. The past several years have witnessed intense efforts to assess the importance of the microphysics of ICF targets, both theoretically and experimentally. On the theory side, first-principles methods based on quantum mechanics have been applied to investigate the properties of warm, dense plasmas. Specifically, self-consistent investigations have recently been performed on the equation of state, thermal conductivity, and opacity of a variety of ICF ablators such as polystyrene (CH), beryllium, carbon, and silicon over a wide range of densities and temperatures. In this talk, we will focus on the most-recent progress on these ab initio HED physics studies, which generally result in favorable comparisons with experiments. Upon incorporation into hydrocodes for ICF simulations, these first-principles ablator-plasma properties have produced significant differences over traditional models in predicting 1-D target performance of ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944. *In collaboration with L. A. Collins, T. R. Boehly, G. W. Collins, J. D. Kress, and V. N. Goncharov.

1 Hz fast-heating fusion driver HAMA pumped by a 10 J green diode-pumped solid-state laser

NASA Astrophysics Data System (ADS)

Mori, Y.; Sekine, T.; Komeda, O.; Nakayama, S.; Ishii, K.; Hanayama, R.; Fujita, K.; Okihara, S.; Satoh, N.; Kurita, T.; Kawashima, T.; Kan, H.; Nakamura, N.; Kondo, T.; Fujine, M.; Azuma, H.; Hioki, T.; Kakeno, M.; Motohiro, T.; Nishimura, Y.; Sunahara, A.; Sentoku, Y.; Kitagawa, Y.

2013-07-01

A Ti : sapphire laser HAMA pumped by a diode-pumped solid-state laser (DPSSL) is developed to enable a high-repetitive inertial confinement fusion (ICF) experiment to be conducted. To demonstrate a counter-irradiation fast-heating fusion scheme, a 3.8 J, 0.4 ns amplified chirped pulse is divided into four beams: two counter-irradiate a target with intensities of 6 × 1013 W cm-2, and the remaining two are pulse-compressed to 110 fs for heating the imploded target with intensities of 2 × 1017 W cm-2. HAMA contributed to the first demonstration by showing that a 10 J class DPSSL is adaptable to ICF experiments and succeeded in DD neutron generation in the repetition mode. Based on HAMA, we can design and develop an integrated repetitive ICF experiment machine by including target injection and tracking.

Antiproton catalyzed microfission/fusion propulsion

NASA Technical Reports Server (NTRS)

Chiang, Pi-Ren; Lewis, Raymond A.; Smith, Gerald A.; Newton, Richard; Dailey, James; Werthman, W. Lance; Chakrabarti, Suman

1994-01-01

Inertial confinement fusion (ICF) utilizing an antiproton catalyzed hybrid fission/fusion target is discussed as a potential energy source for interplanetary propulsion. A proof-of-principle experiment underway at Phillips Laboratory, Kirtland AFB and antiproton trapping experiments at CERN, Geneva, Switzerland, are presented. The ICAN propulsion concept is described and results of performance analyses are reviewed. Future work to further define the ICAN concept is outlined.

Project Icarus: Analysis of Plasma jet driven Magneto-Inertial Fusion as potential primary propulsion driver for the Icarus probe

NASA Astrophysics Data System (ADS)

Stanic, M.; Cassibry, J. T.; Adams, R. B.

2013-05-01

Hopes of sending probes to another star other than the Sun are currently limited by the maturity of advanced propulsion technologies. One of the few candidate propulsion systems for providing interstellar flight capabilities is nuclear fusion. In the past many fusion propulsion concepts have been proposed and some of them have even been explored in detail, Project Daedalus for example. However, as scientific progress in this field has advanced, new fusion concepts have emerged that merit evaluation as potential drivers for interstellar missions. Plasma jet driven Magneto-Inertial Fusion (PJMIF) is one of those concepts. PJMIF involves a salvo of converging plasma jets that form a uniform liner, which compresses a magnetized target to fusion conditions. It is an Inertial Confinement Fusion (ICF)-Magnetic Confinement Fusion (MCF) hybrid approach that has the potential for a multitude of benefits over both ICF and MCF, such as lower system mass and significantly lower cost. This paper concentrates on a thermodynamic assessment of basic performance parameters necessary for utilization of PJMIF as a candidate propulsion system for the Project Icarus mission. These parameters include: specific impulse, thrust, exhaust velocity, mass of the engine system, mass of the fuel required etc. This is a submission of the Project Icarus Study Group.

Effects of magnetization on fusion product trapping and secondary neutron spectra

DOE PAGES

Knapp, Patrick F.; Schmit, Paul F.; Hansen, Stephanie B.; ...

2015-05-14

In magnetizing the fusion fuel in inertial confinement fusion (ICF) systems, we found that the required stagnation pressure and density can be relaxed dramatically. This happens because the magnetic field insulates the hot fuel from the cold pusher and traps the charged fusion burn products. This trapping allows the burn products to deposit their energy in the fuel, facilitating plasma self-heating. Here, we report on a comprehensive theory of this trapping in a cylindrical DD plasma magnetized with a purely axial magnetic field. Using this theory, we are able to show that the secondary fusion reactions can be used tomore » infer the magnetic field-radius product, BR, during fusion burn. This parameter, not ρR, is the primary confinement parameter in magnetized ICF. Using this method, we analyze data from recent Magnetized Liner InertialFusion experiments conducted on the Z machine at Sandia National Laboratories. Furthermore, we show that in these experiments BR ≈ 0.34(+0.14/-0.06) MG · cm, a ~ 14× increase in BR from the initial value, and confirming that the DD-fusion tritons are magnetized at stagnation. Lastly, this is the first experimental verification of charged burn product magnetization facilitated by compression of an initial seed magnetic flux.« less

Neutron imaging with bubble chambers for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Ghilea, Marian C.

One of the main methods to obtain energy from controlled thermonuclear fusion is inertial confinement fusion (ICF), a process where nuclear fusion reactions are initiated by heating and compressing a fuel target, typically in the form of a pellet that contains deuterium and tritium, relying on the inertia of the fuel mass to provide confinement. In inertial confinement fusion experiments, it is important to distinguish failure mechanisms of the imploding capsule and unambiguously diagnose compression and hot spot formation in the fuel. Neutron imaging provides such a technique and bubble chambers are capable of generating higher resolution images than other types of neutron detectors. This thesis explores the use of a liquid bubble chamber to record high yield 14.1 MeV neutrons resulting from deuterium-tritium fusion reactions on ICF experiments. A design tool to deconvolve and reconstruct penumbral and pinhole neutron images was created, using an original ray tracing concept to simulate the neutron images. The design tool proved that misalignment and aperture fabrication errors can significantly decrease the resolution of the reconstructed neutron image. A theoretical model to describe the mechanism of bubble formation was developed. A bubble chamber for neutron imaging with Freon 115 as active medium was designed and implemented for the OMEGA laser system. High neutron yields resulting from deuterium-tritium capsule implosions were recorded. The bubble density was too low for neutron imaging on OMEGA but agreed with the model of bubble formation. The research done in here shows that bubble detectors are a promising technology for the higher neutron yields expected at National Ignition Facility (NIF).

A technique for thick polymer coating of inertial-confinement-fusion targets

NASA Technical Reports Server (NTRS)

Lee, M. C.; Feng, I.-A.; Wang, T. G.; Kim, H.-G.

1983-01-01

A technique to coat a stalk-mounted inertial-confinement fusion (ICF) target with a thick polymer layer has been successfully demonstrated. The polymer solution is first atomized, allowed to coalesce into a droplet, and positioned in a stable acoustic levitating field. The stalk-mounted ICF target is then moved into the acoustic field by manipulating a 3-D positioner to penetrate the surface membrane of the droplet, thus immersing the target in the levitated coating solution. The target inside the droplet is maintained at the center of the levitated liquid using the 3-D positional information provided by two orthogonally placed TV cameras until the drying process is completed. The basic components of the experimental apparatus, including an acoustic levitator, liquid sample deployment device, image acquisition instrumentation, and 3-D positioner, are briefly described.

First quantitative measurements of charged-particle stopping and its dependence on electron temperature and density in Inertial-Confinement-Fusion plasmas

NASA Astrophysics Data System (ADS)

Frenje, J.; Li, C. K.; Séguin, F.; Zylstra, A.; Rinderknecht, H.; Petrasso, R.; Delettrez, J.; Glebov, V.; Sangster, T.

2013-10-01

We report on the first quantitative measurements of charged-particle stopping in Inertial-Confinement-Fusion (ICF) plasmas at various conditions. In these experiments, four charged fusion products from the DD and D3He reactions in D3He gas-filled filled implosions were used to determine the stopping power of ICF plasmas at electron temperatures (Te) , ion temperatures (Ti) , and areal densities (ρR) in the range of 0.6-4.0 keV, 3-14 keV and 2-10 mg/cm2, respectively. The resulting data, in the form of measured energy downshift of the charged fusion products, clearly indicate that the stopping-power function depends strongly on Te. It was also observed that the stopping-power function change in characteristics for higher-density implosions in which ions and electrons equilibrate faster, resulting in higher Te relative to Ti and higher ρR s. These results will be modelled by Landau-Spitzer theory and contrasted to different stopping-power models. This work was partially supported by the US DOE, NLUF, LLE, and GA.

Magnetized Target Fusion Driven by Plasma Liners

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Kirkpatrick, Ronald C.; Knapp, Charles E.; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

Magnetized target fusion is an emerging, relatively unexplored approach to fusion for electrical power and propulsion application. The physical principles of the concept are founded upon both inertial confinement fusion (ICF) and magnetic confinement fusion (MCF). It attempts to combine the favorable attributes of both these orthogonal approaches to fusion, but at the same time, avoiding the extreme technical challenges of both by exploiting a fusion regime intermediate between them. It uses a material liner to compress, heat and contain the fusion reacting plasma (the target plasma) mentally. By doing so, the fusion burn could be made to occur at plasma densities as high as six orders of magnitude higher than conventional MCF such as tokamak, thus leading to an approximately three orders of magnitude reduction in the plasma energy required for ignition. It also uses a transient magnetic field, compressed to extremely high intensity (100's T to 1000T) in the target plasma, to slow down the heat transport to the liner and to increase the energy deposition of charged-particle fusion products. This has several compounding beneficial effects. It leads to longer energy confinement time compared with conventional ICF without magnetized target, and thus permits the use of much lower plasma density to produce reasonable burn-up fraction. The compounding effects of lower plasma density and the magneto-insulation of the target lead to greatly reduced compressional heating power on the target. The increased energy deposition rate of charged-particle fusion products also helps to lower the energy threshold required for ignition and increasing the burn-up fraction. The reduction in ignition energy and the compressional power compound to lead to reduced system size, mass and R&D cost. It is a fusion approach that has an affordable R&D pathway, and appears attractive for propulsion application in the nearer term.

Lawrence Livermore National Laboratories Perspective on Code Development and High Performance Computing Resources in Support of the National HED/ICF Effort

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clouse, C. J.; Edwards, M. J.; McCoy, M. G.

2015-07-07

Through its Advanced Scientific Computing (ASC) and Inertial Confinement Fusion (ICF) code development efforts, Lawrence Livermore National Laboratory (LLNL) provides a world leading numerical simulation capability for the National HED/ICF program in support of the Stockpile Stewardship Program (SSP). In addition the ASC effort provides high performance computing platform capabilities upon which these codes are run. LLNL remains committed to, and will work with, the national HED/ICF program community to help insure numerical simulation needs are met and to make those capabilities available, consistent with programmatic priorities and available resources.

Measurement of Hydrodynamic Growth near Peak Velocity in an Inertial Confinement Fusion Capsule Implosion using a Self-Radiography Technique

NASA Astrophysics Data System (ADS)

Pickworth, L. A.; Hammel, B. A.; Smalyuk, V. A.; MacPhee, A. G.; Scott, H. A.; Robey, H. F.; Landen, O. L.; Barrios, M. A.; Regan, S. P.; Schneider, M. B.; Hoppe, M.; Kohut, T.; Holunga, D.; Walters, C.; Haid, B.; Dayton, M.

2016-07-01

First measurements of hydrodynamic growth near peak implosion velocity in an inertial confinement fusion (ICF) implosion at the National Ignition Facility were obtained using a self-radiographing technique and a preimposed Legendre mode 40, λ =140 μ m , sinusoidal perturbation. These are the first measurements of the total growth at the most unstable mode from acceleration Rayleigh-Taylor achieved in any ICF experiment to date, showing growth of the areal density perturbation of ˜7000 × . Measurements were made at convergences of ˜5 to ˜10 × at both the waist and pole of the capsule, demonstrating simultaneous measurements of the growth factors from both lines of sight. The areal density growth factors are an order of magnitude larger than prior experimental measurements and differed by ˜2 × between the waist and the pole, showing asymmetry in the measured growth factors. These new measurements significantly advance our ability to diagnose perturbations detrimental to ICF implosions, uniquely intersecting the change from an accelerating to decelerating shell, with multiple simultaneous angular views.

Measurement of hydrodynamic growth near peak velocity in an inertial confinement fusion capsule implosion using a self-radiography technique

DOE PAGES

Pickworth, L. A.; Hammel, B. A.; Smalyuk, V. A.; ...

2016-07-11

First measurements of hydrodynamic growth near peak implosion velocity in an inertial confinement fusion (ICF) implosion at the National Ignition Facility were obtained using a self-radiographing technique and a preimposed Legendre mode 40, λ = 140 μm, sinusoidal perturbation. These are the first measurements of the total growth at the most unstable mode from acceleration Rayleigh-Taylor achieved in any ICF experiment to date, showing growth of the areal density perturbation of ~7000×. Measurements were made at convergences of ~5 to ~10× at both the waist and pole of the capsule, demonstrating simultaneous measurements of the growth factors from both linesmore » of sight. The areal density growth factors are an order of magnitude larger than prior experimental measurements and differed by ~2× between the waist and the pole, showing asymmetry in the measured growth factors. As a result, these new measurements significantly advance our ability to diagnose perturbations detrimental to ICF implosions, uniquely intersecting the change from an accelerating to decelerating shell, with multiple simultaneous angular views.« less

Next generation laser for Inertial Confinement Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, C.D.; Beach, J.; Bibeau, C.

1997-07-18

We are in the process of developing and building the ``Mercury`` laser system as the first in a series of a new generation of diode-pumped solid-state Inertial Confinement Fusion (ICF) lasers at LLNL. Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced high energy density (HED) physics applications. Primary performance goals include 10% efficiencies at 10 Hz and a 1-10 ns pulse with 1{omega} energies of 100 J and with 2{omega}/3{omega} frequency conversion.

FY16 LLNL Omega Experimental Programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heeter, R. F.; Ali, S. J.; Benstead, J.

In FY16, LLNL’s High-Energy-Density Physics (HED) and Indirect Drive Inertial Confinement Fusion (ICF-ID) programs conducted several campaigns on the OMEGA laser system and on the EP laser system, as well as campaigns that used the OMEGA and EP beams jointly. Overall, these LLNL programs led 430 target shots in FY16, with 304 shots using just the OMEGA laser system, and 126 shots using just the EP laser system. Approximately 21% of the total number of shots (77 OMEGA shots and 14 EP shots) supported the Indirect Drive Inertial Confinement Fusion Campaign (ICF-ID). The remaining 79% (227 OMEGA shots and 112more » EP shots) were dedicated to experiments for High-Energy-Density Physics (HED). Highlights of the various HED and ICF campaigns are summarized in the following reports. In addition to these experiments, LLNL Principal Investigators led a variety of Laboratory Basic Science campaigns using OMEGA and EP, including 81 target shots using just OMEGA and 42 shots using just EP. The highlights of these are also summarized, following the ICF and HED campaigns. Overall, LLNL PIs led a total of 553 shots at LLE in FY 2016. In addition, LLNL PIs also supported 57 NLUF shots on Omega and 31 NLUF shots on EP, in collaboration with the academic community.« less

Mach-Zehnder Fiber-Optic Links for ICF Diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, E. K., Hermann, H. W.

2012-11-01

This article describes the operation and evolution of Mach-Zehnder links for single-point detectors in inertial confinement fusion experimental facilities, based on the Gamma Reaction History (GRH) diagnostic at the National Ignition Facility.

PhD Dissertation Proposal - Introduction to Dark Mix Concept: Gamma Measurements of Capsule Mixture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meaney, Kevin Daniel

Presentation slides: Intro to Inertial Confinement Fusion; Types of Mixture in ICF capsules; Previous mixture experiments; Dark Mix Concept; Measuring Dark Mix with Gamma Cherenkov Detector; Dissertation Outline.

Inertial Confinement Fusion Annual Report 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

Correll, D

The ICF Annual Report provides documentation of the achievements of the LLNL ICF Program during the fiscal year by the use of two formats: (1) an Overview that is a narrative summary of important results for the fiscal year and (2) a compilation of the articles that previously appeared in the ICF Quarterly Report that year. Both the Overview and Quarterly Report are also on the Web at http://lasers.llnl.gov/lasers/pubs/icfq.html. Beginning in Fiscal Year 1997, the fourth quarter issue of the ICF Quarterly was no longer printed as a separate document but rather included in the ICF Annual. This change providedmore » a more efficient process of documenting our accomplishments with-out unnecessary duplication of printing. In addition we introduced a new document, the ICF Program Monthly Highlights. Starting with the September 1997 issue and each month following, the Monthly Highlights will provide a brief description of noteworthy activities of interest to our DOE sponsors and our stakeholders. The underlying theme for LLNL's ICF Program research continues to be defined within DOE's Defense Programs missions and goals. In support of these missions and goals, the ICF Program advances research and technology development in major interrelated areas that include fusion target theory and design, target fabrication, target experiments, and laser and optical science and technology. While in pursuit of its goal of demonstrating thermonuclear fusion ignition and energy gain in the laboratory, the ICF Program provides research and development opportunities in fundamental high-energy-density physics and supports the necessary research base for the possible long-term application of inertial fusion energy for civilian power production. ICF technologies continue to have spin-off applications for additional government and industrial use. In addition to these topics, the ICF Annual Report covers non-ICF funded, but related, laser research and development and associated applications. We also provide a short summary of the quarterly activities within Nova laser operations, Beamlet laser operations, and National Ignition Facility laser design. LLNL's ICF Program falls within DOE's national ICF program, which includes the Nova and Beamlet (LLNL), OMEGA (University of Rochester Laboratory for Laser Energetics), Nike (Naval Research Laboratory), and Trident (Los Alamos National Laboratory) laser facilities. The Particle Beam Fusion Accelerator (Z) and Saturn pulsed-power facilities are at Sandia National Laboratories. General Atomics, Inc., develops and provides many of the targets for the above experimental facilities. Many of the ICF Annual Report articles are co-authored with our colleagues from these other ICF institutions.« less

Impact of first-principles properties of deuterium-tritium on inertial confinement fusion target designsa)

NASA Astrophysics Data System (ADS)

Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; McCrory, R. L.; Skupsky, S.; Collins, L. A.; Kress, J. D.; Militzer, B.

2015-05-01

A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium-tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF "path" to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κQMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ˜2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.

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

NASA Astrophysics Data System (ADS)

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.

Ion Implantation Doping of Inertial Confinement Fusion Targets

DOE PAGES

Shin, S. J.; Lee, J. R. I.; van Buuren, T.; ...

2017-12-19

Controlled doping of inertial confinement fusion (ICF) targets is needed to enable nuclear diagnostics of implosions. Here in this study, we demonstrate that ion implantation with a custom-designed carousel holder can be used for azimuthally uniform doping of ICF fuel capsules made from a glow discharge polymer (GDP). Particular emphasis is given to the selection of the initial wall thickness of GDP capsules as well as implantation and postimplantation annealing parameters in order to minimize capsule deformation during a postimplantation thermal treatment step. In contrast to GDP, ion-implanted high-density carbon exhibits excellent thermal stability and ~100% implantation efficiency for themore » entire range of ion doses studied (2 × 10 14 to 1 × 10 16 cm -2) and for annealing temperatures up to 700°C. Lastly, we demonstrate a successful doping of planar Al targets with isotopes of Kr and Xe to doses of ~10 17 cm -2.« less

Ion Implantation Doping of Inertial Confinement Fusion Targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shin, S. J.; Lee, J. R. I.; van Buuren, T.

Controlled doping of inertial confinement fusion (ICF) targets is needed to enable nuclear diagnostics of implosions. Here in this study, we demonstrate that ion implantation with a custom-designed carousel holder can be used for azimuthally uniform doping of ICF fuel capsules made from a glow discharge polymer (GDP). Particular emphasis is given to the selection of the initial wall thickness of GDP capsules as well as implantation and postimplantation annealing parameters in order to minimize capsule deformation during a postimplantation thermal treatment step. In contrast to GDP, ion-implanted high-density carbon exhibits excellent thermal stability and ~100% implantation efficiency for themore » entire range of ion doses studied (2 × 10 14 to 1 × 10 16 cm -2) and for annealing temperatures up to 700°C. Lastly, we demonstrate a successful doping of planar Al targets with isotopes of Kr and Xe to doses of ~10 17 cm -2.« less

High-energy krypton fluoride lasers for inertial fusion.

PubMed

Obenschain, Stephen; Lehmberg, Robert; Kehne, David; Hegeler, Frank; Wolford, Matthew; Sethian, John; Weaver, James; Karasik, Max

2015-11-01

Laser fusion researchers have realized since the 1970s that the deep UV light from excimer lasers would be an advantage as a driver for robust high-performance capsule implosions for inertial confinement fusion (ICF). Most of this research has centered on the krypton-fluoride (KrF) laser. In this article we review the advantages of the KrF laser for direct-drive ICF, the history of high-energy KrF laser development, and the present state of the art and describe a development path to the performance needed for laser fusion and its energy application. We include descriptions of the architecture and performance of the multi-kilojoule Nike KrF laser-target facility and the 700 J Electra high-repetition-rate KrF laser that were developed at the U.S. Naval Research Laboratory. Nike and Electra are the most advanced KrF lasers for inertial fusion research and energy applications.

Next-generation laser for Inertial Confinement Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, C.D.; Deach, R.J.; Bibeau, C.

1997-09-29

We report on the progress in developing and building the Mercury laser system as the first in a series of a new generation of diode- pumped solid-state Inertial Confinement Fusion (ICF) lasers at Lawrence Livermore National Laboratory (LLNL). Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced high energy density (HED) physics applications. Primary performance goals include 10% efficiencies at 10 Hz and a 1-10 ns pulse with 1 omega energies of 100 J and with 2 omega/3 omega frequency conversion.

High-resolution Imaging of Deuterium-Tritium Capsule Implosions on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Bachmann, Benjamin; Rygg, Ryan; Collins, Gilbert; Patel, Pravesh

2017-10-01

Highly-resolved 3-D simulations of inertial confinement fusion (ICF) implosions predict a hot spot plasma that exhibits complex micron-scale structure originating from a variety of 3-D perturbations. Experimental diagnosis of these conditions requires high spatial resolution imaging techniques. X-ray penumbral imaging can improve the spatial resolution over pinhole imaging while simultaneously increasing the detected photon yield at x-ray energies where the ablator opacity becomes negligible. Here we report on the first time-integrated x-ray penumbral imaging experiments of ICF capsule implosions at the National Ignition Facility that achieved spatial resolution as high as 4 micrometer. 6 to 30 keV hot spot images from layered DT implosions will be presented from a variety of experimental ICF campaigns, revealing previously unseen detail. It will be discussed how these and future results can be used to improve our physics understanding of inertially confined fusion plasmas by enabling spatially resolved measurements of hot spot properties, such as radiation energy, temperature or derived quantities. This work performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

Progress in Direct-Drive Inertial Confinement Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCrory, R.L.; Meyerhofer, D.D.; Betti, R.

Significant progress in direct-drive inertial confinement fusion (ICF) research has been made since the completion of the 60-beam, 30-kJ UV OMEGA Laser System [T. R. Boehly, Opt. Commun. 133, 495 (1997)] in 1995. A theory of ignition requirements, applicable to any ICF concept, has been developed. Detailed understanding of laser-plasma coupling, electron thermal transport, and hot-electron preheating has lead to the measurement of neutron-averaged areal densities of ~200 mg/cm^2 in cryogenic target implosions. These correspond to an estimated peak fuel density in excess of 100 g/cm^3 and are in good agreement with hydrodynamic simulations. The implosions were performed using anmore » 18-kJ drive pulse designed to put the converging fuel on an adiabat of two. The polar-drive concept will allow direct-drive-ignition research on the National Ignition Facility while it is configured for indirect drive. Advanced ICF ignition concepts—fast ignition [Tabak et al., Phys. Plasmas 1, 1626 (1994)] and shock ignition [R. Betti et al., Phys. Rev. Lett. 98, 155001 (2007)]—have the potential to significantly reduce ignition driver energies and/or provide higher target gain.« less

Progress in direct-drive inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCrory, R. L.; Meyerhofer, D. D.; Betti, R.

Significant progress in direct-drive inertial confinement fusion (ICF) research has been made since the completion of the 60-beam, 30-kJ{sub UV} OMEGA Laser System [Boehly, Opt. Commun. 133, 495 (1997)] in 1995. A theory of ignition requirements, applicable to any ICF concept, has been developed. Detailed understanding of laser-plasma coupling, electron thermal transport, and hot-electron preheating has lead to the measurement of neutron-averaged areal densities of {approx}200 mg/cm{sup 2} in cryogenic target implosions. These correspond to an estimated peak fuel density in excess of 100 g/cm{sup 3} and are in good agreement with hydrodynamic simulations. The implosions were performed using anmore » 18-kJ drive pulse designed to put the converging fuel on an adiabat of two. The polar-drive concept will allow direct-drive-ignition research on the National Ignition Facility while it is configured for indirect drive. Advanced ICF ignition concepts - fast ignition [Tabak et al., Phys. Plasmas 1, 1626 (1994)] and shock ignition [Betti et al., Phys. Rev. Lett. 98, 155001 (2007)] - have the potential to significantly reduce ignition driver energies and/or provide higher target gain.« less

Fluorescence and absorption spectroscopy for warm dense matter studies and ICF plasma diagnostics

NASA Astrophysics Data System (ADS)

Hansen, S. B.; Harding, E. C.; Knapp, P. F.; Gomez, M. R.; Nagayama, T.; Bailey, J. E.

2018-05-01

The burning core of an inertial confinement fusion (ICF) plasma produces bright x-rays at stagnation that can directly diagnose core conditions essential for comparison to simulations and understanding fusion yields. These x-rays also backlight the surrounding shell of warm, dense matter, whose properties are critical to understanding the efficacy of the inertial confinement and global morphology. We show that the absorption and fluorescence spectra of mid-Z impurities or dopants in the warm dense shell can reveal the optical depth, temperature, and density of the shell and help constrain models of warm, dense matter. This is illustrated by the example of a high-resolution spectrum collected from an ICF plasma with a beryllium shell containing native iron impurities. Analysis of the iron K-edge provides model-independent diagnostics of the shell density (2.3 × 1024 e/cm3) and temperature (10 eV), while a 12-eV red shift in Kβ and 5-eV blue shift in the K-edge discriminate among models of warm dense matter: Both shifts are well described by a self-consistent field model based on density functional theory but are not fully consistent with isolated-atom models using ad-hoc density effects.

Compact torus accelerator as a driver for ICF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tobin, M.T.; Meier, W.R.; Morse, E.C.

1986-01-01

The authors have carried out further investigations of the technical issues associated with using a compact torus (CT) accelerator as a driver for inertial confinement fusion (ICF). In a CT accelerator, a magnetically confined, torus-shaped plasma is compressed, accelerated, and focused by two concentric electrodes. After its initial formation, the torus shape is maintained for lifetimes exceeding 1 ms by inherent poloidal and toroidal currents. Hartman suggests acceleration and focusing of such a plasma ring will not cause dissolution within certain constraints. In this study, we evaluated a point design based on an available capacitor bank energy of 9.2 MJ.more » This accelerator, which was modeled by a zero-dimensional code, produces a xenon plasma ring with a 0.73-cm radius, a velocity of 4.14 x 10/sup 9/ cm/s, and a mass of 4.42 ..mu..g. The energy of the plasma ring as it leaves the accelerator is 3.8 MJ, or 41% of the capacitor bank energy. Our studies confirm the feasibility of producing a plasma ring with the characteristics required to induce fusion in an ICF target with a gain greater than 50. The low cost and high efficiency of the CT accelerator are particularly attractive. Uncertainties concerning propagation, accelerator lifetime, and power supply must be resolved to establish the viability of the accelerator as an ICF driver.« less

A review on ab initio studies of static, transport, and optical properties of polystyrene under extreme conditions for inertial confinement fusion applications

NASA Astrophysics Data System (ADS)

Hu, S. X.; Collins, L. A.; Boehly, T. R.; Ding, Y. H.; Radha, P. B.; Goncharov, V. N.; Karasiev, V. V.; Collins, G. W.; Regan, S. P.; Campbell, E. M.

2018-05-01

Polystyrene (CH), commonly known as "plastic," has been one of the widely used ablator materials for capsule designs in inertial confinement fusion (ICF). Knowing its precise properties under high-energy-density conditions is crucial to understanding and designing ICF implosions through radiation-hydrodynamic simulations. For this purpose, systematic ab initio studies on the static, transport, and optical properties of CH, in a wide range of density and temperature conditions (ρ = 0.1 to 100 g/cm3 and T = 103 to 4 × 106 K), have been conducted using quantum molecular dynamics (QMD) simulations based on the density functional theory. We have built several wide-ranging, self-consistent material-properties tables for CH, such as the first-principles equation of state, the QMD-based thermal conductivity (κQMD) and ionization, and the first-principles opacity table. This paper is devoted to providing a review on (1) what results were obtained from these systematic ab initio studies; (2) how these self-consistent results were compared with both traditional plasma-physics models and available experiments; and (3) how these first-principles-based properties of polystyrene affect the predictions of ICF target performance, through both 1-D and 2-D radiation-hydrodynamic simulations. In the warm dense regime, our ab initio results, which can significantly differ from predictions of traditional plasma-physics models, compared favorably with experiments. When incorporated into hydrocodes for ICF simulations, these first-principles material properties of CH have produced significant differences over traditional models in predicting 1-D/2-D target performance of ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility. Finally, we will discuss the implications of these studies on the current small-margin ICF target designs using a CH ablator.

Performance and Mix Measurements of Indirect Drive Cu-Doped Be Implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casey, D.  T.; Woods, D. T.; Smalyuk, V. A.

2015-05-19

The ablator couples energy between the driver and fusion fuel in inertial confinement fusion (ICF). Because of its low opacity, high solid density, and material properties, beryllium has long been considered an ideal ablator for ICF ignition experiments at the National Ignition Facility. We report here the first indirect drive Be implosions driven with shaped laser pulses and diagnosed with fusion yield at the OMEGA laser. The results show good performance with an average DD neutron yield of ~2 × 10⁹ at a convergence ratio of R₀/R ~ 10 and little impact due to the growth of hydrodynamic instabilities andmore » mix. In addition, the effect of adding an inner liner of W between the Be and DD is demonstrated.« less

The Physics of Advanced High-Gain Targets for Inertial Fusion Energy

NASA Astrophysics Data System (ADS)

Perkins, L. John

2010-11-01

In ca. 2011-2012, the National Ignition Facility is poised to demonstrate fusion ignition and gain in the laboratory for the first time. This key milestone in the development of inertial confinement fusion (ICF) can be expected to engender interest in the development of inertial fusion energy (IFE) and expanded efforts on a number of advanced targets that may achieve high fusion energy gain at lower driver energies. In this tutorial talk, we will discuss the physics underlying ICF ignition and thermonuclear burn, examine the requirements for high gain, and outline candidate R&D programs that will be required to assess the performance of these target concepts under various driver systems including lasers, heavy-ions and pulsed power. Such target concepts include those operating by fast ignition, shock ignition, impact ignition, dual-density, magnetically-insulated, one- and two-sided drive, etc., some of which may have potential to burn advanced, non-DT fusion fuels. We will then delineate the role of such targets in their application to the production of high average fusion power. Here, systems studies of IFE economics suggest that we should strive for target fusion gains of around 100 at drive energies of 1MJ, together with corresponding rep-rates of up to 10Hz and driver electrical efficiencies around 15%. In future years, there may be exciting opportunities to study such ``innovative confinement concepts'' with prospects of fielding them on facilities such as NIF to obtain high fusion energy gains on a single shot basis.

The first experiments on the national ignition facility

NASA Astrophysics Data System (ADS)

Landen, O. L.; Glenzer, S.; Froula, D.; Dewald, E.; Suter, L. J.; Schneider, M.; Hinkel, D.; Fernandez, J.; Kline, J.; Goldman, S.; Braun, D.; Celliers, P.; Moon, S.; Robey, H.; Lanier, N.; Glendinning, G.; Blue, B.; Wilde, B.; Jones, O.; Schein, J.; Divol, L.; Kalantar, D.; Campbell, K.; Holder, J.; McDonald, J.; Niemann, C.; MacKinnon, A.; Collins, R.; Bradley, D.; Eggert, J.; Hicks, D.; Gregori, G.; Kirkwood, R.; Niemann, C.; Young, B.; Foster, J.; Hansen, F.; Perry, T.; Munro, D.; Baldis, H.; Grim, G.; Heeter, R.; Hegelich, B.; Montgomery, D.; Rochau, G.; Olson, R.; Turner, R.; Workman, J.; Berger, R.; Cohen, B.; Kruer, W.; Langdon, B.; Langer, S.; Meezan, N.; Rose, H.; Still, B.; Williams, E.; Dodd, E.; Edwards, J.; Monteil, M.-C.; Stevenson, M.; Thomas, B.; Coker, R.; Magelssen, G.; Rosen, P.; Stry, P.; Woods, D.; Weber, S.; Alvarez, S.; Armstrong, G.; Bahr, R.; Bourgade, J.-L.; Bower, D.; Celeste, J.; Chrisp, M.; Compton, S.; Cox, J.; Constantin, C.; Costa, R.; Duncan, J.; Ellis, A.; Emig, J.; Gautier, C.; Greenwood, A.; Griffith, R.; Holdner, F.; Holtmeier, G.; Hargrove, D.; James, T.; Kamperschroer, J.; Kimbrough, J.; Landon, M.; Lee, D.; Malone, R.; May, M.; Montelongo, S.; Moody, J.; Ng, E.; Nikitin, A.; Pellinen, D.; Piston, K.; Poole, M.; Rekow, V.; Rhodes, M.; Shepherd, R.; Shiromizu, S.; Voloshin, D.; Warrick, A.; Watts, P.; Weber, F.; Young, P.; Arnold, P.; Atherton, L.; Bardsley, G.; Bonanno, R.; Borger, T.; Bowers, M.; Bryant, R.; Buckman, S.; Burkhart, S.; Cooper, F.; Dixit, S.; Erbert, G.; Eder, D.; Ehrlich, B.; Felker, B.; Fornes, J.; Frieders, G.; Gardner, S.; Gates, C.; Gonzalez, M.; Grace, S.; Hall, T.; Haynam, C.; Heestand, G.; Henesian, M.; Hermann, M.; Hermes, G.; Huber, S.; Jancaitis, K.; Johnson, S.; Kauffman, B.; Kelleher, T.; Kohut, T.; Koniges, A. E.; Labiak, T.; Latray, D.; Lee, A.; Lund, D.; Mahavandi, S.; Manes, K. R.; Marshall, C.; McBride, J.; McCarville, T.; McGrew, L.; Menapace, J.; Mertens, E.; Munro, D.; Murray, J.; Neumann, J.; Newton, M.; Opsahl, P.; Padilla, E.; Parham, T.; Parrish, G.; Petty, C.; Polk, M.; Powell, C.; Reinbachs, I.; Rinnert, R.; Riordan, B.; Ross, G.; Robert, V.; Tobin, M.; Sailors, S.; Saunders, R.; Schmitt, M.; Shaw, M.; Singh, M.; Spaeth, M.; Stephens, A.; Tietbohl, G.; Tuck, J.; van Wonterghem, B.; Vidal, R.; Wegner, P.; Whitman, P.; Williams, K.; Winward, K.; Work, K.; Wallace, R.; Nobile, A.; Bono, M.; Day, B.; Elliott, J.; Hatch, D.; Louis, H.; Manzenares, R.; O'Brien, D.; Papin, P.; Pierce, T.; Rivera, G.; Ruppe, J.; Sandoval, D.; Schmidt, D.; Valdez, L.; Zapata, K.; MacGowan, B.; Eckart, M.; Hsing, W.; Springer, P.; Hammel, B.; Moses, E.; Miller, G.

2006-06-01

A first set of shock propagation, laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics.

Next-generation laser for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, C; Bibeau, C; Bayramian, A

1998-03-13

We are developing and building the ''Mercury'' laser system as the first in a series of a new generation of diode-pumped solid-state lasers (DPSSL) for advanced high energy density (HED) physics experiments at LLNL. Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced Inertial Confinement Fusion (ICF) goals. Primary performance goals include 10% efficiencies at 10 Hz and a <10 ns pulse with l {omega} energies of 100 J and with 2 {omega}/3 {omega} frequency conversion. Achieving this performance will provide a near term capability for HED experiments and prove the potential of DPSSLsmore » for inertial fusion energy (IFE).« less

Simulations of inertial confinement fusion driven by a novel synchrotron-radiation-based x-ray igniter

NASA Astrophysics Data System (ADS)

Shlyaptsev, Vyacheslav N.; Tatchyn, Roman O.

2004-01-01

The advantages and challenges of using a powerful x-ray source for the fast ignition of compressed Inertial Confinement Fusion (ICF) targets have been considered. The requirements for such a source together with the optics to focus the x-rays onto compressed DT cores lead to a conceptual design based on Energy Recovery Linacs (ERLs) and long wigglers to produce x-ray pulses with the appropriate phase space properties. A comparative assessment of the parameters of the igniter system indicates that the technologies for building it, although expensive, are physically achievable. Our x-ray fast ignition (XFI) scheme requires substantially smaller energy for the initiation of nuclear fusion reactions than other methods.

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, S. X., E-mail: shu@lle.rochester.edu; Goncharov, V. N.; Boehly, T. R.

2015-05-15

A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into accountmore » in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κ{sub QMD}), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ∼2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.« less

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

DOE PAGES

Hu, S. X.; Goncharov, V. N.; Boehly, T. R.; ...

2015-04-20

In this study, a comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximatelymore » taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (K QMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of –2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.« less

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

DOE PAGES

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

2016-12-07

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D 2 and DT layer Inertial Confinement Fusion (ICF) implosions that can access low-to-moderate hot spot convergence ratio (1230) 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 CR’s of 12-17, and the hot spot formation is well understood, demonstratedmore » by 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.« less

First-principles studies on the equation-of-state, thermal-conductivity, and opacity of deuterium-tritium and polystyrene (CH) for inertial confinement fusion applications

DOE PAGES

Hu, Suxing; Collins, Lee A.; Goncharov, V. N.; ...

2016-05-26

Using first-principles (FP) methods, we have performed ab initio compute for the equation of state (EOS), thermal conductivity, and opacity of deuterium-tritium (DT) in a wide range of densities and temperatures for inertial confinement fusion (ICF) applications. These systematic investigations have recently been expanded to accurately compute the plasma properties of CH ablators under extreme conditions. In particular, the first-principles EOS and thermal-conductivity tables of CH are self-consistently built from such FP calculations, which are benchmarked by experimental measurements. When compared with the traditional models used for these plasma properties in hydrocodes, significant differences have been identified in the warmmore » dense plasma regime. When these FP-calculated properties of DT and CH were used in our hydrodynamic simulations of ICF implosions, we found that the target performance in terms of neutron yield and energy gain can vary by a factor of 2 to 3, relative to traditional model simulations.« less

Plasma Stopping Power Measurements Relevant to Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

McEvoy, Aaron; Herrmann, Hans; Kim, Yongho; Hoffman, Nelson; Schmitt, Mark; Rubery, Michael; Garbett, Warren; Horsfield, Colin; Gales, Steve; Zylstra, Alex; Gatu Johnson, Maria; Frenje, Johan; Petrasso, Richard; Marshall, Frederic; Batha, Steve

2015-11-01

Ignition in inertial confinement fusion (ICF) experiments may be achieved if the alpha particle energy deposition results in a thermonuclear burn wave induced in the dense DT fuel layer surrounding the hotspot. As such, understanding the physics of particle energy loss in a plasma is of critical importance to designing ICF experiments. Experiments have validated various stopping power models under select ne and Te conditions, however there remain unexplored regimes where models predict differing rates of energy deposition. An upcoming experiment at the Omega laser facility will explore charged particle stopping in CH plastic capsule ablators across a range of plasma conditions (ne between 1024 cm-3 and 1025 cm-3 and Te on the order of hundreds of eV). Plasma conditions will be measured using x-ray and gamma ray diagnostics, while plasma stopping power will be measured using charged particle energy loss measurements. Details on the experiment and the theoretical models to be tested will be presented.

Nova Upgrade: A proposed ICF facility to demonstrate ignition and gain, revision 1

NASA Astrophysics Data System (ADS)

1992-07-01

The present objective of the national Inertial Confinement Fusion (ICF) Program is to determine the scientific feasibility of compressing and heating a small mass of mixed deuterium and tritium (DT) to conditions at which fusion occurs and significant energy is released. The potential applications of ICF will be determined by the resulting fusion energy yield (amount of energy produced) and gain (ratio of energy released to energy required to heat and compress the DT fuel). Important defense and civilian applications, including weapons physics, weapons effects simulation, and ultimately the generation of electric power will become possible if yields of 100 to 1,000 MJ and gains exceeding approximately 50 can be achieved. Once ignition and propagating bum producing modest gain (2 to 10) at moderate drive energy (1 to 2 MJ) has been achieved, the extension to high gain (greater than 50) is straightforward. Therefore, the demonstration of ignition and modest gain is the final step in establishing the scientific feasibility of ICF. Lawrence Livermore National Laboratory (LLNL) proposes the Nova Upgrade Facility to achieve this demonstration by the end of the decade. This facility would be constructed within the existing Nova building at LLNL for a total cost of approximately $400 M over the proposed FY 1995-1999 construction period. This report discusses this facility.

Direct-drive inertial confinement fusion research at the Laboratory for Laser Energetics: charting the path to thermonuclear ignition

NASA Astrophysics Data System (ADS)

McCrory, R. L.; Regan, S. P.; Loucks, S. J.; Meyerhofer, D. D.; Skupsky, S.; Betti, R.; Boehly, T. R.; Craxton, R. S.; Collins, T. J. B.; Delettrez, J. A.; Edgell, D.; Epstein, R.; Fletcher, K. A.; Freeman, C.; Frenje, J. A.; Glebov, V. Yu.; Goncharov, V. N.; Harding, D. R.; Igumenshchev, I. V.; Keck, R. L.; Kilkenny, J. D.; Knauer, J. P.; Li, C. K.; Marciante, J.; Marozas, J. A.; Marshall, F. J.; Maximov, A. V.; McKenty, P. W.; Myatt, J.; Padalino, S.; Petrasso, R. D.; Radha, P. B.; Sangster, T. C.; Séguin, F. H.; Seka, W.; Smalyuk, V. A.; Soures, J. M.; Stoeckl, C.; Yaakobi, B.; Zuegel, J. D.

2005-10-01

Significant theoretical and experimental progress continues to be made at the University of Rochester's Laboratory for Laser Energetics (LLE), charting the path to direct-drive inertial confinement fusion (ICF) ignition. Direct drive offers the potential for higher-gain implosions than x-ray drive and is a leading candidate for an inertial fusion energy power plant. LLE's direct-drive ICF ignition target designs for the National Ignition Facility (NIF) are based on hot-spot ignition. A cryogenic target with a spherical DT-ice layer, within or without a foam matrix, enclosed by a thin plastic shell, will be directly irradiated with ~1.5 MJ of laser energy. Cryogenic and plastic/foam (surrogate-cryogenic) targets that are hydrodynamically scaled from these ignition target designs are imploded on the 60-beam, 30 kJ, UV OMEGA laser system to validate the key target physics issues, including energy coupling, hydrodynamic instabilities and implosion symmetry. Prospects for direct-drive ignition on the NIF are extremely favourable, even while it is in its x-ray-drive irradiation configuration, with the development of the polar-direct-drive concept. A high-energy petawatt capability is being constructed at LLE next to the existing 60-beam OMEGA compression facility. This OMEGA EP (extended performance) laser will add two short-pulse, 2.6 kJ beams to the OMEGA laser system to backlight direct-drive ICF implosions and study fast-ignition physics with focused intensities up to 6 × 1020 W cm-2.

Kinetic studies of ICF implosions

DOE PAGES

Kagan, Grigory; Herrmann, H. W.; Kim, Y. -H.; ...

2016-05-26

Here, kinetic effects on inertial confinement fusion have been investigated. In particular, inter-ion-species diffusion and suprathermal ion distribution have been analyzed. The former drives separation of the fuel constituents in the hot reacting core and governs mix at the shell/fuel interface. The latter underlie measurements obtained with nuclear diagnostics, including the fusion yield and inferred ion burn temperatures. Basic mechanisms behind and practical consequences from these effects are discussed.

Fluorescence and absorption spectroscopy for warm dense matter studies and ICF plasma diagnostics

DOE PAGES

Hansen, Stephanie B.; Harding, Eric C.; Knapp, Patrick F.; ...

2018-03-07

The burning core of an inertial confinement fusion (ICF) plasma produces bright x-rays at stagnation that can directly diagnose core conditions essential for comparison to simulations and understanding fusion yields. These x-rays also backlight the surrounding shell of warm, dense matter, whose properties are critical to understanding the efficacy of the inertial confinement and global morphology. In this work, we show that the absorption and fluorescence spectra of mid-Z impurities or dopants in the warm dense shell can reveal the optical depth, temperature, and density of the shell and help constrain models of warm, dense matter. This is illustrated bymore » the example of a high-resolution spectrum collected from an ICF plasma with a beryllium shell containing native iron impurities. Lastly, analysis of the iron K-edge provides model-independent diagnostics of the shell density (2.3 × 10 24 e/cm 3) and temperature (10 eV), while a 12-eV red shift in Kβ and 5-eV blue shift in the K-edge discriminate among models of warm dense matter: Both shifts are well described by a self-consistent field model based on density functional theory but are not fully consistent with isolated-atom models using ad-hoc density effects.« less

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

NASA Astrophysics Data System (ADS)

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.

Lead (Pb) Hohlraum: Target for Inertial Fusion Energy

PubMed Central

Ross, J. S.; Amendt, P.; Atherton, L. J.; Dunne, M.; Glenzer, S. H.; Lindl, J. D.; Meeker, D.; Moses, E. I.; Nikroo, A.; Wallace, R.

2013-01-01

Recent progress towards demonstrating inertial confinement fusion (ICF) ignition at the National Ignition Facility (NIF) has sparked wide interest in Laser Inertial Fusion Energy (LIFE) for carbon-free large-scale power generation. A LIFE-based fleet of power plants promises clean energy generation with no greenhouse gas emissions and a virtually limitless, widely available thermonuclear fuel source. For the LIFE concept to be viable, target costs must be minimized while the target material efficiency or x-ray albedo is optimized. Current ICF targets on the NIF utilize a gold or depleted uranium cylindrical radiation cavity (hohlraum) with a plastic capsule at the center that contains the deuterium and tritium fuel. Here we show a direct comparison of gold and lead hohlraums in efficiently ablating deuterium-filled plastic capsules with soft x rays. We report on lead hohlraum performance that is indistinguishable from gold, yet costing only a small fraction. PMID:23486285

Lead (Pb) hohlraum: target for inertial fusion energy.

PubMed

Ross, J S; Amendt, P; Atherton, L J; Dunne, M; Glenzer, S H; Lindl, J D; Meeker, D; Moses, E I; Nikroo, A; Wallace, R

2013-01-01

Recent progress towards demonstrating inertial confinement fusion (ICF) ignition at the National Ignition Facility (NIF) has sparked wide interest in Laser Inertial Fusion Energy (LIFE) for carbon-free large-scale power generation. A LIFE-based fleet of power plants promises clean energy generation with no greenhouse gas emissions and a virtually limitless, widely available thermonuclear fuel source. For the LIFE concept to be viable, target costs must be minimized while the target material efficiency or x-ray albedo is optimized. Current ICF targets on the NIF utilize a gold or depleted uranium cylindrical radiation cavity (hohlraum) with a plastic capsule at the center that contains the deuterium and tritium fuel. Here we show a direct comparison of gold and lead hohlraums in efficiently ablating deuterium-filled plastic capsules with soft x rays. We report on lead hohlraum performance that is indistinguishable from gold, yet costing only a small fraction.

A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility

NASA Astrophysics Data System (ADS)

Sutcliffe, G. D.; Milanese, L. M.; Orozco, D.; Lahmann, B.; Gatu Johnson, M.; Séguin, F. H.; Sio, H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.; Park, H.-S.; Rygg, J. R.; Casey, D. T.; Bionta, R.; Turnbull, D. P.; Huntington, C. M.; Ross, J. S.; Zylstra, A. B.; Rosenberg, M. J.; Glebov, V. Yu.

2016-11-01

CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint of the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.

A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility.

PubMed

Sutcliffe, G D; Milanese, L M; Orozco, D; Lahmann, B; Gatu Johnson, M; Séguin, F H; Sio, H; Frenje, J A; Li, C K; Petrasso, R D; Park, H-S; Rygg, J R; Casey, D T; Bionta, R; Turnbull, D P; Huntington, C M; Ross, J S; Zylstra, A B; Rosenberg, M J; Glebov, V Yu

2016-11-01

CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint of the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.

A review on ab initio studies of static, transport, and optical properties of polystyrene under extreme conditions for inertial confinement fusion applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, L. A.; Boehly, T. R.; Ding, Y. H.

Polystyrene (CH), commonly known as “plastic,” has been one of the widely used ablator materials for capsule designs in inertial confinement fusion (ICF). Knowing its precise properties under high-energy-density conditions is crucial to understanding and designing ICF implosions through radiation–hydrodynamic simulations. For this purpose, systematic ab initio studies on the static, transport, and optical properties of CH, in a wide range of density and temperature conditions (ρ= 0.1 to 100 g/cm 3 and T = 10 3 to 4 × 10 6K), have been conducted using quantum molecular dynamics (QMD) simulations based on the density functional theory. We have builtmore » several wide-ranging, self-consistent material-properties tables for CH, such as the first-principles equation of state (FPEOS), the QMD-based thermal conductivity (Κ QMD) and ionization, and the first-principles opacity table (FPOT). This paper is devoted to providing a review on (1) what results were obtained from these systematic ab initio studies; (2) how these self-consistent results were compared with both traditional plasma-physics models and available experiments; and (3) how these first-principles–based properties of polystyrene affect the predictions of ICF target performance, through both 1-D and 2-D radiation–hydrodynamic simulations. In the warm dense regime, our ab initio results, which can significantly differ from predictions of traditional plasma-physics models, compared favorably with experiments. When incorporated into hydrocodes for ICF simulations, these first-principles material properties of CH have produced significant differences over traditional models in predicting 1-D/2-D target performance of ICF implosions on OMEGA and direct-drive–ignition designs for the National Ignition Facility. Lastly, we will discuss the implications of these studies on the current small-margin ICF target designs using a CH ablator.« less

A review on ab initio studies of static, transport, and optical properties of polystyrene under extreme conditions for inertial confinement fusion applications

DOE PAGES

Collins, L. A.; Boehly, T. R.; Ding, Y. H.; ...

2018-03-23

Polystyrene (CH), commonly known as “plastic,” has been one of the widely used ablator materials for capsule designs in inertial confinement fusion (ICF). Knowing its precise properties under high-energy-density conditions is crucial to understanding and designing ICF implosions through radiation–hydrodynamic simulations. For this purpose, systematic ab initio studies on the static, transport, and optical properties of CH, in a wide range of density and temperature conditions (ρ= 0.1 to 100 g/cm 3 and T = 10 3 to 4 × 10 6K), have been conducted using quantum molecular dynamics (QMD) simulations based on the density functional theory. We have builtmore » several wide-ranging, self-consistent material-properties tables for CH, such as the first-principles equation of state (FPEOS), the QMD-based thermal conductivity (Κ QMD) and ionization, and the first-principles opacity table (FPOT). This paper is devoted to providing a review on (1) what results were obtained from these systematic ab initio studies; (2) how these self-consistent results were compared with both traditional plasma-physics models and available experiments; and (3) how these first-principles–based properties of polystyrene affect the predictions of ICF target performance, through both 1-D and 2-D radiation–hydrodynamic simulations. In the warm dense regime, our ab initio results, which can significantly differ from predictions of traditional plasma-physics models, compared favorably with experiments. When incorporated into hydrocodes for ICF simulations, these first-principles material properties of CH have produced significant differences over traditional models in predicting 1-D/2-D target performance of ICF implosions on OMEGA and direct-drive–ignition designs for the National Ignition Facility. Lastly, we will discuss the implications of these studies on the current small-margin ICF target designs using a CH ablator.« less

ICF quarterly report January - March 1997 volume 7, number 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, J

The National Ignition Facility Project The mission of the National Ignition Facility (NIF) is to produce ignition and modest energy gain in inertial confinement fusion (ICF) targets. Achieving these goals will maintain U.S. world leadership in ICF and will directly benefit the U.S. Department of Energy (DOE) missions in national security, science and technology, energy resources, and industrial competitiveness. Development and operation of the NIF are consistent with DOE goals for environmental quality, openness to the community, and nuclear nonproliferation and arms control. Although the primary mission of inertial fusion is for defense applications, inertial fusion research will provide criticalmore » information for the development of inertial fusion energy. The NIF, under construction at Lawrence Livermore National Laboratory (LLNL), is a cornerstone of the DOE's science-based Stockpile Stewardship Program for addressing high-energy-density physics issues in the absence of nuclear weapons testing. In pursuit of this mission, the DOE's Defense Programs has developed a state-of-the-art capability with the NIF to investigate high-energy-density physics in the laboratory with a microfusion capability for defense and energy applications. As a Strategic System Acquisition, the NIF Project has a separate and disciplined reporting chain to DOE as shown below.« less

Self-pinched transport for ion-driven inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welch, D.R.; Olson, C.L.

Efficient transport of intense ion beams is necessary for ion-driven inertial confinement fusion (ICF). The self-pinched transport scheme involves the focusing of an ion beam to a radius of about 1 cm or less. At this radius, using the beam`s self-magnetic field for confinement, the ion beam propagates through the reactor chamber to an ICF target. A promising regime for self-pinched transport involves the injection of a high current beam into an initially neutral gas at about 200 mTorr less. A simple equilibrium theory of a beam with a temporally pinching radial envelope predicts that large confining magnetic fields aremore » possible with net currents of more than 50% of the beam current. The magnitude of these fields is strongly dependent on the rate of ionization of the given ion species. The authors have simulated ion-beam propagation, using the hybrid code IPROP, which self-consistently calculates the gas breakdown and electromagnetic fields. In agreement, with the theory, a propagation window of 20-200 mTorr of argon is calculated for a 50 kA, 5 MeV proton beam similar to the parameters of the SABRE accelerator at Sandia National Laboratories. The authors present simulations of the focusing and propagation of the SABRE beam, with the purpose of designing a self-pinch experiment.« less

Seeding of capsule instability growth by fill tubes and support rods for inertial confinement fusion implosions

NASA Astrophysics Data System (ADS)

Macphee, Andrew; Casey, Daniel; Clark, Daniel; Field, John; Haan, Steven; Hammel, Bruce; Kroll, Jeremy; Landen, Otto; Martinez, David; Milovich, Jose; Nikroo, Abbas; Rice, Neal; Robey, Harry; Smalyuk, Vladimir; Stadermann, Michael; Weber, Christopher; Lawrence Livermore National Laboratory Collaboration; Atomics Collaboration, General

2016-10-01

Features associated with the target support tent and deuterium-tritium fuel fill tube and support rods can seed hydrodynamic instabilities leading to degraded performance for inertial confinement fusion (ICF) experiments at the National Ignition Facility. We performed in-flight radiography of ICF capsules in the vicinity of the capsule support tent and fill tube surrogates to investigate instability growth associated with these features. For both plastic and high density carbon ablators, the shadow of the 10 μm diameter glass fill-tube cast by the x-ray spots on the hohlraum wall were observed to imprint radial instabilities around the fill tube/capsule interface. Similarly, instability growth was observed for the shadow cast by 12 μm diameter silicon carbide capsule support rods mounted orthogonal to the fill tube as a tent alternative for a plastic ablator. The orientation of the shadows is consistent with raytracing. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

First-principles equation of state of polystyrene and its effect on inertial confinement fusion implosions

DOE PAGES

Hu, S. X.; Collins, L. A.; Goncharov, V. N.; ...

2015-10-14

Obtaining an accurate equation of state (EOS) of polystyrene (CH) is crucial to reliably design inertial confinement fusion (ICF) capsules using CH/CH-based ablators. Thus, with first-principles calculations, we have investigated the extended EOS of CH over a wide range of plasma conditions (ρ = 0.1 to 100 g/cm 3 and T = 1,000 to 4,000,000 K). When compared with the widely used SESAME-EOS table, the first-principles equation of state (FPEOS) of CH has shown significant differences in the low-temperature regime, in which strong coupling and electron degeneracy play an essential role in determining plasma properties. Hydrodynamic simulations of cryogenic targetmore » implosions on OMEGA using the FPEOS table of CH have predicted ~5% reduction in implosion velocity and ~30% decrease in neutron yield in comparison with the usual SESAME simulations. This is attributed to the ~10% lower mass ablation rate of CH predicted by FPEOS. Simulations using CH-FPEOS show better agreement with measurements of Hugoniot temperature and scattered lights from ICF implosions.« less

First-principles equation of state of polystyrene and its effect on inertial confinement fusion implosions.

PubMed

Hu, S X; Collins, L A; Goncharov, V N; Kress, J D; McCrory, R L; Skupsky, S

2015-10-01

Obtaining an accurate equation of state (EOS) of polystyrene (CH) is crucial to reliably design inertial confinement fusion (ICF) capsules using CH/CH-based ablators. With first-principles calculations, we have investigated the extended EOS of CH over a wide range of plasma conditions (ρ=0.1to100g/cm(3) and T=1000 to 4,000,000 K). When compared with the widely used SESAME-EOS table, the first-principles equation of state (FPEOS) of CH has shown significant differences in the low-temperature regime, in which strong coupling and electron degeneracy play an essential role in determining plasma properties. Hydrodynamic simulations of cryogenic target implosions on OMEGA using the FPEOS table of CH have predicted ∼30% decrease in neutron yield in comparison with the usual SESAME simulations. This is attributed to the ∼5% reduction in implosion velocity that is caused by the ∼10% lower mass ablation rate of CH predicted by FPEOS. Simulations using CH-FPEOS show better agreement with measurements of Hugoniot temperature and scattered light from ICF implosions.

Picosecond imaging of inertial confinement fusion plasmas using electron pulse-dilation

NASA Astrophysics Data System (ADS)

Hilsabeck, T. J.; Nagel, S. R.; Hares, J. D.; Kilkenny, J. D.; Bell, P. M.; Bradley, D. K.; Dymoke-Bradshaw, A. K. L.; Piston, K.; Chung, T. M.

2017-02-01

Laser driven inertial confinement fusion (ICF) plasmas typically have burn durations on the order of 100 ps. Time resolved imaging of the x-ray self emission during the hot spot formation is an important diagnostic tool which gives information on implosion symmetry, transient features and stagnation time. Traditional x-ray gated imagers for ICF use microchannel plate detectors to obtain gate widths of 40-100 ps. The development of electron pulse-dilation imaging has enabled a 10X improvement in temporal resolution over legacy instruments. In this technique, the incoming x-ray image is converted to electrons at a photocathode. The electrons are accelerated with a time-varying potential that leads to temporal expansion as the electron signal transits the tube. This expanded signal is recorded with a gated detector and the effective temporal resolution of the composite system can be as low as several picoseconds. An instrument based on this principle, known as the Dilation X-ray Imager (DIXI) has been constructed and fielded at the National Ignition Facility. Design features and experimental results from DIXI will be presented.

On the utility of antiprotons as drivers for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Perkins, L. John; Orth, Charles D.; Tabak, Max

2004-10-01

In contrast to the large mass, complexity and recirculating power of conventional drivers for inertial confinement fusion (ICF), antiproton annihilation offers a specific energy of 90 MJ µg-1 and thus a unique form of energy packaging and delivery. In principle, antiproton drivers could provide a profound reduction in system mass for advanced space propulsion by ICF. We examine the physics underlying the use of antiprotons ( \\bar{p} ) to drive various classes of high-yield ICF targets by the methods of volumetric ignition, hotspot ignition and fast ignition. The useable fraction of annihilation deposition energy is determined for both \\bar{p} -driven ablative compression and \\bar{p} -driven fast ignition, in association with zero- and one-dimensional target burn models. Thereby, we deduce scaling laws for the number of injected antiprotons required per capsule, together with timing and focal spot requirements. The kinetic energy of the injected antiproton beam required to penetrate to the desired annihilation point is always small relative to the deposited annihilation energy. We show that heavy metal seeding of the fuel and/or ablator is required to optimize local deposition of annihilation energy and determine that a minimum of ~3 × 1015 injected antiprotons will be required to achieve high yield (several hundred megajoules) in any target configuration. Target gains—i.e. fusion yields divided by the available p- \\bar{p} annihilation energy from the injected antiprotons ( 1.88\\,GeV/\\bar{p} )—range from ~3 for volumetric ignition targets to ~600 for fast ignition targets. Antiproton-driven ICF is a speculative concept, and the handling of antiprotons and their required injection precision—temporally and spatially—will present significant technical challenges. The storage and manipulation of low-energy antiprotons, particularly in the form of antihydrogen, is a science in its infancy and a large scale-up of antiproton production over present supply methods would be required to embark on a serious R&D programme for this application.

Measurement of the complex transmittance of large optical elements with Ptychographical Iterative Engine.

PubMed

Wang, Hai-Yan; Liu, Cheng; Veetil, Suhas P; Pan, Xing-Chen; Zhu, Jian-Qiang

2014-01-27

Wavefront control is a significant parameter in inertial confinement fusion (ICF). The complex transmittance of large optical elements which are often used in ICF is obtained by computing the phase difference of the illuminating and transmitting fields using Ptychographical Iterative Engine (PIE). This can accurately and effectively measure the transmittance of large optical elements with irregular surface profiles, which are otherwise not measurable using commonly used interferometric techniques due to a lack of standard reference plate. Experiments are done with a Continue Phase Plate (CPP) to illustrate the feasibility of this method.

Ignition and Inertial Confinement Fusion at The National Ignition Facility

NASA Astrophysics Data System (ADS)

Moses, Edward I.

2016-10-01

The National Ignition Facility (NIF), the world's largest and most powerful laser system for inertial confinement fusion (ICF) and for studying high-energy-density (HED) science, is now operational at Lawrence Livermore National Laboratory (LLNL). The NIF is now conducting experiments to commission the laser drive, the hohlraum and the capsule and to develop the infrastructure needed to begin the first ignition experiments in FY 2010. Demonstration of ignition and thermonuclear bum in the laboratory is a major NIF goal. NIF will achieve this by concentrating the energy from the 192 beams into a mm3-sized target and igniting a deuterium-tritium mix, liberating more energy than is required to initiate the fusion reaction. NIP's ignition program is a national effort managed via the National Ignition Campaign (NIC). The NIC has two major goals: execution of DT ignition experiments starting in FY20l0 with the goal of demonstrating ignition and a reliable, repeatable ignition platform by the conclusion of the NIC at the end of FY2012. The NIC will also develop the infrastructure and the processes required to operate NIF as a national user facility. The achievement of ignition at NIF will demonstrate the scientific feasibility of ICF and focus worldwide attention on laser fusion as a viable energy option. A laser fusion-based energy concept that builds on NIF, known as LIFE (Laser Inertial Fusion Energy), is currently under development. LIFE is inherently safe and can provide a global carbon-free energy generation solution in the 21st century. This paper describes recent progress on NIF, NIC, and the LIFE concept.

Definition of Ignition in Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Christopherson, A. R.; Betti, R.

2017-10-01

Defining ignition in inertial confinement fusion (ICF) is an unresolved problem. In ICF, a distinction must be made between the ignition of the hot spot and the propagation of the burn wave in the surrounding dense fuel. Burn propagation requires that the hot spot is robustly ignited and the dense shell exhibits enough areal density. Since most of the energy gain comes from burning the dense shell, in a scale of increasing yields, hot-spot ignition comes before high gains. Identifying this transition from hot-spot ignition to burn-wave propagation is key to defining ignition in general terms applicable to all fusion approaches that use solid DT fuel. Ad hoc definitions such as gain = 1 or doubling the temperature are not generally valid. In this work, we show that it is possible to identify the onset of ignition through a unique value of the yield amplification defined as the ratio of the fusion yield including alpha-particle deposition to the fusion yield without alphas. Since the yield amplification is a function of the fractional alpha energy fα =EαEα 2Ehs 2Ehs (a measurable quantity), it appears possible not only to define ignition but also to measure the onset of ignition by the experimental inference of the fractional alpha energy and yield amplification. This material is based upon work supported by the Department of Energy Office of Fusion Energy Services under Award Number DE-FC02-04ER54789 and National Nuclear Security Administration under Award Number DE-NA0001944.

Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets

NASA Technical Reports Server (NTRS)

Annamalai, P.; Lee, M. C.; Crawley, R. L.; Downs, R. L.

1985-01-01

An inertial confinement fusion (ICF) target made of polystyrene is first levitated in an acoustic field. The surface of the target is then etched using an appropriate solution (e.g., cyclohexane) to enhance the wetting characteristics. A specially prepared polyvinyl alcohol solution is atomized using an acoustic atomizer and deposited on the surface of the target. The solution is air dried to form a thin coating (2 microns) on the target (outside diameter of about 350-850 microns). Thicker coatings are obtained by repeated applications of the coating solutions. Preliminary results indicate that uniform coatings may be achievable on the targets with a background surface smoothness in the order of 1000 A.

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

NASA Astrophysics Data System (ADS)

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.

Inertial confinement fusion quarterly report, October--December 1992. Volume 3, No. 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dixit, S.N.

1992-12-31

This report contains papers on the following topics: The Beamlet Front End: Prototype of a new pulse generation system;imaging biological objects with x-ray lasers; coherent XUV generation via high-order harmonic generation in rare gases; theory of high-order harmonic generation; two-dimensional computer simulations of ultra- intense, short-pulse laser-plasma interactions; neutron detectors for measuring the fusion burn history of ICF targets; the recirculator; and lasnex evolves to exploit computer industry advances.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutcliffe, G. D.; Milanese, L. M.; Orozco, D.

CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint ofmore » the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.« less

First measurements of deuterium-tritium and deuterium-deuterium fusion reaction yields in ignition-scalable direct-drive implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forrest, C. J.; Radha, P. B.; Knauer, J. P.

In this study, the deuterium-tritium (D-T) and deuterium-deuterium neutron yield ratio in cryogenic inertial confinement fusion (ICF) experiments is used to examine multifluid effects, traditionally not included in ICF modeling. This ratio has been measured for ignition-scalable direct-drive cryogenic DT implosions at the Omega Laser Facility using a high-dynamic-range neutron time-of-flight spectrometer. The experimentally inferred yield ratio is consistent with both the calculated values of the nuclear reaction rates and the measured preshot target-fuel composition. These observations indicate that the physical mechanisms that have been proposed to alter the fuel composition, such as species separation of the hydrogen isotopes, aremore » not significant during the period of peak neutron production in ignition-scalable cryogenic direct-drive DT implosions.« less

First measurements of deuterium-tritium and deuterium-deuterium fusion reaction yields in ignition-scalable direct-drive implosions

DOE PAGES

Forrest, C. J.; Radha, P. B.; Knauer, J. P.; ...

2017-03-03

In this study, the deuterium-tritium (D-T) and deuterium-deuterium neutron yield ratio in cryogenic inertial confinement fusion (ICF) experiments is used to examine multifluid effects, traditionally not included in ICF modeling. This ratio has been measured for ignition-scalable direct-drive cryogenic DT implosions at the Omega Laser Facility using a high-dynamic-range neutron time-of-flight spectrometer. The experimentally inferred yield ratio is consistent with both the calculated values of the nuclear reaction rates and the measured preshot target-fuel composition. These observations indicate that the physical mechanisms that have been proposed to alter the fuel composition, such as species separation of the hydrogen isotopes, aremore » not significant during the period of peak neutron production in ignition-scalable cryogenic direct-drive DT implosions.« less

Uniform hydrogen fuel layers for inertial fusion targets by microgravity

NASA Technical Reports Server (NTRS)

Parks, P. B.; Fagaly, Robert L.

1994-01-01

A critical concern in the fabrication of targets for inertial confinement fusion (ICF) is ensuring that the hydrogenic (D(sub 2) or DT) fuel layer maintains spherical symmetry. Solid layered targets have structural integrity, but lack the needed surface smoothness. Liquid targets are inherently smooth, but suffer from gravitationally induced sagging. One method to reduce the effective gravitational field environment is freefall insertion into the target chamber. Another method to counterbalance field gravitational force is to use an applied magnetic field combined with a gradient field to induce a magnetic dipole force on the liquid fuel layer. Based on time dependent calculations of the dynamics of the liquid fuel layer in microgravity environments, we show that it may be possible to produce a liquid layered ICF target that satisfies both smoothness and symmetry requirements.

A Computational Study of a Circular Interface Richtmyer-Meshkov Instability in MHD

NASA Astrophysics Data System (ADS)

Maxon, William; Black, Wolfgang; Denissen, Nicholas; McFarland, Jacob; Los Alamos National Laboratory Collaboration; University of Missouri Shock Tube Laboratory Team

2017-11-01

The Richtmyer-Meshkov instability (RMI) is a hydrodynamic instability that appears in several high energy density applications such as inertial confinement fusion (ICF). In ICF, as the thermonuclear fuel is being compressed it begins to mix due to fluid instabilities including the RMI. This mixing greatly decreases the energy output. The RMI occurs when two fluids of different densities are impulsively accelerated and the pressure and density gradients are misaligned. In magnetohydrodynamics (MHD), the RMI may be suppressed by introducing a magnetic field in an electrically conducting fluid, such as a plasma. This suppression has been studied as a possible mechanism for improving confinement in ICF targets. In this study,ideal MHD simulations are performed with a circular interface impulsively accelerated by a shock wave in the presence of a magnetic field. These simulations are executed with the research code FLAG, a multiphysics, arbitrary Lagrangian/Eulerian, hydrocode developed and utilized at Los Alamos National Laboratory. The simulation results will be assessed both quantitatively and qualitatively to examine the stabilization mechanism. These simulations will guide ongoing MHD experiments at the University of Missouri Shock Tube Facility.

New amplifying laser concept for inertial fusion driver

NASA Astrophysics Data System (ADS)

Mourou, G. A.; Labaune, C.; Hulin, D.; Galvanauskas, A.

2008-05-01

This paper presents a new amplifying laser concept designed to produce high energy in either short or long pulses using coherent or incoherent addition of few millions fibers. These are called respectively CAN for Coherent Amplification Network and FAN for Fiber Amplification Network. The fibers would be large core or Large Mode Area (LMA) which have demonstrated up to 10, mJ output energy per fiber1. Such a system could meet the driver criteria of Inertial Fusion Energy (IFE) power plants based on Inertial Confinement Fusion (ICF), in particular high efficiency and high repetition rate.

Cryogenic Hydrogen Fuel for Controlled Inertial Confinement Fusion (Cryogenic Target Factory Concept Based on FST-Layering Method)

NASA Astrophysics Data System (ADS)

Aleksandrova, I. V.; Koresheva, E. R.; Koshelev, I. E.; Krokhin, O. N.; Nikitenko, A. I.; Osipov, I. E.

2017-12-01

A central element of a power plant based on inertial confinement fusion (ICF) is a target with cryogenic hydrogen fuel that should be delivered to the center of a reactor chamber with a high accuracy and repetition rate. Therefore, a cryogenic target factory (CTF) is an integral part of any ICF reactor. A promising way to solve this problem consists in the FST layering method developed at the Lebedev Physical Institute (LPI). This method (rapid fuel layering inside moving free-standing targets) is unique, having no analogs in the world. The further development of FST-layering technologies is implemented in the scope of the LPI program for the creation of a modular CTF and commercialization of the obtained results. In this report, we discuss our concept of CTF (CTF-LPI) that exhibits the following distinctive features: using a FST-layering technology for the elaboration of an in-line production of cryogenic targets, using an effect of quantum levitation of high-temperature superconductors (HTSCs) in magnetic field for noncontacting manipulation, transport, and positioning of the free-standing cryogenic targets, as well as in using a Fourier holography technique for an on-line characterization and tracking of the targets flying into the reactor chamber. The results of original experimental and theoretical investigations performed at LPI indicate that the existing and developing target fabrication capabilities and technologies can be applied to ICF target production. The unique scientific, engineering, and technological base developed in Russia at LPI allows one to make a CTFLPI prototype for mass production of targets and delivery thereof at the required velocity into the ICF reactor chamber.

A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility

DOE PAGES

Sutcliffe, G. D.; Milanese, L. M.; Orozco, D.; ...

2016-08-05

CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint ofmore » the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.« less

A novel method to recover DD fusion proton CR-39 data corrupted by fast ablator ions at OMEGA and the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutcliffe, G. D., E-mail: gdsut@mit.edu; Milanese, L. M.; Orozco, D.

2016-11-15

CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully. The technique involves removing material from the surface of the CR-39 to a depth beyond the endpoint ofmore » the ablator ion tracks. The technique preserves signal magnitude (yield) as well as structure in radiograph images. The technique is effective when signal particle range is at least 10 μm deeper than the necessary bulk material removal.« less

Laser Program Annual Report - 1979 Unclassified Excerpts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lindl, J D

The objective of the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) program is to demonstrate the scientific feasibility of ICF for military applications (to develop and utilize the capability to study nuclear weapons physics in support of the weapons program) and for energy-directed uses in the civilian sector. The demonstration of scientific feasibility for both military and civilian objectives will require achieving gains on the order of 10 to 100 in fusion microexplosions. Our major near-term milestones include the attainment of high compression, one-hundred to one-thousand times (100 to 1000X) liquid D-T density in the thermonuclear fuel andmore » ignition of thermonuclear burn. In 1979, our laser fusion experiments and analysis programs focused on two important areas related to achieving this goal: conducting x-ray-driven implosions of a variety of D-T-filled fuel capsule's to unprecedented high densities ({approx}> 50X liquid D-T density) and the determination of the scaling of hot electrons and thermal radiation in hohlraums.« less

Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

PubMed

Herrmann, Hans W; Mack, Joseph M; Young, Carlton S; Malone, Robert M; Stoeffl, Wolfgang; Horsfield, Colin J

2008-10-01

Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.

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

NASA Astrophysics Data System (ADS)

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.

First-principles thermal conductivity of warm-dense deuterium plasmas for inertial confinement fusion applications.

PubMed

Hu, S X; Collins, L A; Boehly, T R; Kress, J D; Goncharov, V N; Skupsky, S

2014-04-01

Thermal conductivity (κ) of both the ablator materials and deuterium-tritium (DT) fuel plays an important role in understanding and designing inertial confinement fusion (ICF) implosions. The extensively used Spitzer model for thermal conduction in ideal plasmas breaks down for high-density, low-temperature shells that are compressed by shocks and spherical convergence in imploding targets. A variety of thermal-conductivity models have been proposed for ICF hydrodynamic simulations of such coupled and degenerate plasmas. The accuracy of these κ models for DT plasmas has recently been tested against first-principles calculations using the quantum molecular-dynamics (QMD) method; although mainly for high densities (ρ > 100 g/cm3), large discrepancies in κ have been identified for the peak-compression conditions in ICF. To cover the wide range of density-temperature conditions undergone by ICF imploding fuel shells, we have performed QMD calculations of κ for a variety of deuterium densities of ρ = 1.0 to 673.518 g/cm3, at temperatures varying from T = 5 × 103 K to T = 8 × 106 K. The resulting κQMD of deuterium is fitted with a polynomial function of the coupling and degeneracy parameters Γ and θ, which can then be used in hydrodynamic simulation codes. Compared with the "hybrid" Spitzer-Lee-More model currently adopted in our hydrocode lilac, the hydrosimulations using the fitted κQMD have shown up to ∼20% variations in predicting target performance for different ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility (NIF). The lower the adiabat of an imploding shell, the more variations in predicting target performance using κQMD. Moreover, the use of κQMD also modifies the shock conditions and the density-temperature profiles of the imploding shell at early implosion stage, which predominantly affects the final target performance. This is in contrast to the previous speculation that κQMD changes mainly the inside ablation process during the hot-spot formation of an ICF implosion.

First-principles thermal conductivity of warm-dense deuterium plasmas for inertial confinement fusion applications

NASA Astrophysics Data System (ADS)

Hu, S. X.; Collins, L. A.; Boehly, T. R.; Kress, J. D.; Goncharov, V. N.; Skupsky, S.

2014-04-01

Thermal conductivity (κ) of both the ablator materials and deuterium-tritium (DT) fuel plays an important role in understanding and designing inertial confinement fusion (ICF) implosions. The extensively used Spitzer model for thermal conduction in ideal plasmas breaks down for high-density, low-temperature shells that are compressed by shocks and spherical convergence in imploding targets. A variety of thermal-conductivity models have been proposed for ICF hydrodynamic simulations of such coupled and degenerate plasmas. The accuracy of these κ models for DT plasmas has recently been tested against first-principles calculations using the quantum molecular-dynamics (QMD) method; although mainly for high densities (ρ > 100 g/cm3), large discrepancies in κ have been identified for the peak-compression conditions in ICF. To cover the wide range of density-temperature conditions undergone by ICF imploding fuel shells, we have performed QMD calculations of κ for a variety of deuterium densities of ρ = 1.0 to 673.518 g/cm3, at temperatures varying from T = 5 × 103 K to T = 8 × 106 K. The resulting κQMD of deuterium is fitted with a polynomial function of the coupling and degeneracy parameters Γ and θ, which can then be used in hydrodynamic simulation codes. Compared with the "hybrid" Spitzer-Lee-More model currently adopted in our hydrocode lilac, the hydrosimulations using the fitted κQMD have shown up to ˜20% variations in predicting target performance for different ICF implosions on OMEGA and direct-drive-ignition designs for the National Ignition Facility (NIF). The lower the adiabat of an imploding shell, the more variations in predicting target performance using κQMD. Moreover, the use of κQMD also modifies the shock conditions and the density-temperature profiles of the imploding shell at early implosion stage, which predominantly affects the final target performance. This is in contrast to the previous speculation that κQMD changes mainly the inside ablation process during the hot-spot formation of an ICF implosion.

On the importance of minimizing "coast-time" in x-ray driven inertially confined fusion implosions

NASA Astrophysics Data System (ADS)

Hurricane, O. A.; Kritcher, A.; Callahan, D. A.; Landen, O.; Patel, P. K.; Springer, P. T.; Casey, D. T.; Dewald, E. L.; Dittrich, T. R.; Döppner, T.; Hinkel, D. E.; Berzak Hopkins, L. F.; Kline, J.; Le Pape, S.; Ma, T.; MacPhee, A. G.; Moore, A.; Pak, A.; Park, H.-S.; Ralph, J.; Salmonson, J. D.; Widmann, K.

2017-09-01

By the time an inertially confined fusion (ICF) implosion has converged a factor of 20, its surface area has shrunk 400 × , making it an inefficient x-ray energy absorber. So, ICF implosions are traditionally designed to have the laser drive shut off at a time, toff, well before bang-time, tBT, for a coast-time of t coast = t B T - t o f f > 1 ns. High-foot implosions on NIF showed a strong dependence of many key ICF performance quantities on reduced coast-time (by extending the duration of laser power after the peak power is first reached), most notably stagnation pressure and fusion yield. Herein we show that the ablation pressure, pabl, which drives high-foot implosions, is essentially triangular in temporal shape, and that reducing tcoast boosts pabl by as much as ˜ 2 × prior to stagnation thus increasing fuel and hot-spot compression and implosion speed. One-dimensional simulations are used to track hydrodynamic characteristics for implosions with various coast-times and various assumed rates of hohlraum cooling after toff to illustrate how the late-time conditions exterior to the implosion can impact the fusion performance. A simple rocket model-like analytic theory demonstrates that reducing coast-time can lead to a ˜ 15 % higher implosion velocity because the reduction in x-ray absorption efficiency at late-time is somewhat compensated by small ( ˜ 5 % - 10 %) ablator mass remaining. Together with the increased ablation pressure, the additional implosion speed for short coast-time implosions can boost the stagnation pressure by ˜ 2 × as compared to a longer coast-time version of the same implosion. Four key dimensionless parameters are identified and we find that reducing coast-time to as little as 500 ps still provides some benefit. Finally, we show how the high-foot implosion data is consistent with the above mentioned picture.

On the importance of minimizing “coast-time” in x-ray driven inertially confined fusion implosions

DOE PAGES

Hurricane, O. A.; Kritcher, A.; Callahan, D. A.; ...

2017-09-01

By the time an inertially confined fusion (ICF) implosion has converged a factor of 20, its surface area has shrunk 400×, making it an inefficient x-ray energy absorber. So, ICF implosions are traditionally designed to have the laser drive shut off at a time, t off, well before bang-time, t BT, for a coast-time of t coast = t BT – t off > 1 ns. High-foot implosions on NIF showed a strong dependence of many key ICF performance quantities on reduced coast-time (by extending the duration of laser power after the peak power is first reached), most notably stagnationmore » pressure and fusion yield. Herein we show that the ablation pressure, p abl, which drives high-foot implosions, is essentially triangular in temporal shape, and that reducing t coast boosts p abl by as much as ~2× prior to stagnation thus increasing fuel and hot-spot compression and implosion speed. One-dimensional simulations are used to track hydrodynamic characteristics for implosions with various coast-times and various assumed rates of hohlraum cooling after t off to illustrate how the late-time conditions exterior to the implosion can impact the fusion performance. A simple rocket model-like analytic theory demonstrates that reducing coast-time can lead to a ~15% higher implosion velocity because the reduction in x-ray absorption efficiency at late-time is somewhat compensated by small (~5%–10%) ablator mass remaining. Together with the increased ablation pressure, the additional implosion speed for short coast-time implosions can boost the stagnation pressure by ~2× as compared to a longer coast-time version of the same implosion. Four key dimensionless parameters are identified and we find that reducing coast-time to as little as 500 ps still provides some benefit. Lastly, we show how the high-foot implosion data is consistent with the above mentioned picture.« less

On the importance of minimizing “coast-time” in x-ray driven inertially confined fusion implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurricane, O. A.; Kritcher, A.; Callahan, D. A.

By the time an inertially confined fusion (ICF) implosion has converged a factor of 20, its surface area has shrunk 400×, making it an inefficient x-ray energy absorber. So, ICF implosions are traditionally designed to have the laser drive shut off at a time, t off, well before bang-time, t BT, for a coast-time of t coast = t BT – t off > 1 ns. High-foot implosions on NIF showed a strong dependence of many key ICF performance quantities on reduced coast-time (by extending the duration of laser power after the peak power is first reached), most notably stagnationmore » pressure and fusion yield. Herein we show that the ablation pressure, p abl, which drives high-foot implosions, is essentially triangular in temporal shape, and that reducing t coast boosts p abl by as much as ~2× prior to stagnation thus increasing fuel and hot-spot compression and implosion speed. One-dimensional simulations are used to track hydrodynamic characteristics for implosions with various coast-times and various assumed rates of hohlraum cooling after t off to illustrate how the late-time conditions exterior to the implosion can impact the fusion performance. A simple rocket model-like analytic theory demonstrates that reducing coast-time can lead to a ~15% higher implosion velocity because the reduction in x-ray absorption efficiency at late-time is somewhat compensated by small (~5%–10%) ablator mass remaining. Together with the increased ablation pressure, the additional implosion speed for short coast-time implosions can boost the stagnation pressure by ~2× as compared to a longer coast-time version of the same implosion. Four key dimensionless parameters are identified and we find that reducing coast-time to as little as 500 ps still provides some benefit. Lastly, we show how the high-foot implosion data is consistent with the above mentioned picture.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Stephanie B.; Harding, Eric C.; Knapp, Patrick F.

The burning core of an inertial confinement fusion (ICF) plasma produces bright x-rays at stagnation that can directly diagnose core conditions essential for comparison to simulations and understanding fusion yields. These x-rays also backlight the surrounding shell of warm, dense matter, whose properties are critical to understanding the efficacy of the inertial confinement and global morphology. In this work, we show that the absorption and fluorescence spectra of mid-Z impurities or dopants in the warm dense shell can reveal the optical depth, temperature, and density of the shell and help constrain models of warm, dense matter. This is illustrated bymore » the example of a high-resolution spectrum collected from an ICF plasma with a beryllium shell containing native iron impurities. Lastly, analysis of the iron K-edge provides model-independent diagnostics of the shell density (2.3 × 10 24 e/cm 3) and temperature (10 eV), while a 12-eV red shift in Kβ and 5-eV blue shift in the K-edge discriminate among models of warm dense matter: Both shifts are well described by a self-consistent field model based on density functional theory but are not fully consistent with isolated-atom models using ad-hoc density effects.« less

One-dimensional Lagrangian implicit hydrodynamic algorithm for Inertial Confinement Fusion applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramis, Rafael, E-mail: rafael.ramis@upm.es

A new one-dimensional hydrodynamic algorithm, specifically developed for Inertial Confinement Fusion (ICF) applications, is presented. The scheme uses a fully conservative Lagrangian formulation in planar, cylindrical, and spherically symmetric geometries, and supports arbitrary equations of state with separate ion and electron components. Fluid equations are discretized on a staggered grid and stabilized by means of an artificial viscosity formulation. The space discretized equations are advanced in time using an implicit algorithm. The method includes several numerical parameters that can be adjusted locally. In regions with low Courant–Friedrichs–Lewy (CFL) number, where stability is not an issue, they can be adjusted tomore » optimize the accuracy. In typical problems, the truncation error can be reduced by a factor between 2 to 10 in comparison with conventional explicit algorithms. On the other hand, in regions with high CFL numbers, the parameters can be set to guarantee unconditional stability. The method can be integrated into complex ICF codes. This is demonstrated through several examples covering a wide range of situations: from thermonuclear ignition physics, where alpha particles are managed as an additional species, to low intensity laser–matter interaction, where liquid–vapor phase transitions occur.« less

Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping

PubMed Central

Depierreux, S.; Yahia, V.; Goyon, C.; Loisel, G.; Masson-Laborde, P. -E.; Borisenko, N.; Orekhov, A.; Rosmej, O.; Rienecker, T.; Labaune, C.

2014-01-01

Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime. PMID:24938756

Compact Torus plasma ring accelerator: a new type driver for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartman, C.W.; Eddleman, J.L.; Hammer, J.H.

1986-08-22

We discuss the acceleration of magnetically-confined plasma rings to provide a driver for ICF. The acceleration of plasma rings is predicted to be efficient and following focusing, to generate ion-bombardment power in the range 10/sup 15/ to 10/sup 16/ W/cm/sup 2/ at a total deposition energy of multimegajoules. The simplicity of plasma ring accelerator suggests that a 5 MJ (on target) driver would cost in the range 1 to 5 $/joule. First experimental tests of the accelerator are described.

Process for manufacture of inertial confinement fusion targets and resulting product

DOEpatents

Masnari, Nino A.; Rensel, Walter B.; Robinson, Merrill G.; Solomon, David E.; Wise, Kensall D.; Wuttke, Gilbert H.

1982-01-01

An ICF target comprising a spherical pellet of fusion fuel surrounded by a concentric shell; and a process for manufacturing the same which includes the steps of forming hemispheric shells of a silicon or other substrate material, adhering the shell segments to each other with a fuel pellet contained concentrically therein, then separating the individual targets from the parent substrate. Formation of hemispheric cavities by deposition or coating of a mold substrate is also described. Coatings or membranes may also be applied to the interior of the hemispheric segments prior to joining.

Measuring the shock impedance mismatch between high-density carbon and deuterium at the National Ignition Facility

DOE PAGES

Millot, M.; Celliers, P. M.; Sterne, P. A.; ...

2018-04-18

Fine-grained diamond, or high-density carbon (HDC), is being used as an ablator for inertial confinement fusion (ICF) research at the National Ignition Facility (NIF). Accurate equation of state (EOS) knowledge over a wide range of phase space is critical in the design and analysis of integrated ICF experiments. Here in this paper, we report shock and release measurements of the shock impedance mismatch between HDC and liquid deuterium conducted during shock-timing experiments having a first shock in the ablator ranging between 8 and 14 Mbar. Using ultrafast Doppler imaging velocimetry to track the leading shock front, we characterize the shockmore » velocity discontinuity upon the arrival of the shock at the HDC/liquid deuterium interface. Comparing the experimental data with tabular EOS models used to simulate integrated ICF experiments indicates the need for an improved multiphase EOS model for HDC in order to achieve a significant increase in neutron yield in indirect-driven ICF implosions with HDC ablators.« less

Measuring the shock impedance mismatch between high-density carbon and deuterium at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Millot, M.; Celliers, P. M.; Sterne, P. A.; Benedict, L. X.; Correa, A. A.; Hamel, S.; Ali, S. J.; Baker, K. L.; Berzak Hopkins, L. F.; Biener, J.; Collins, G. W.; Coppari, F.; Divol, L.; Fernandez-Panella, A.; Fratanduono, D. E.; Haan, S. W.; Le Pape, S.; Meezan, N. B.; Moore, A. S.; Moody, J. D.; Ralph, J. E.; Ross, J. S.; Rygg, J. R.; Thomas, C.; Turnbull, D. P.; Wild, C.; Eggert, J. H.

2018-04-01

Fine-grained diamond, or high-density carbon (HDC), is being used as an ablator for inertial confinement fusion (ICF) research at the National Ignition Facility (NIF). Accurate equation of state (EOS) knowledge over a wide range of phase space is critical in the design and analysis of integrated ICF experiments. Here, we report shock and release measurements of the shock impedance mismatch between HDC and liquid deuterium conducted during shock-timing experiments having a first shock in the ablator ranging between 8 and 14 Mbar. Using ultrafast Doppler imaging velocimetry to track the leading shock front, we characterize the shock velocity discontinuity upon the arrival of the shock at the HDC/liquid deuterium interface. Comparing the experimental data with tabular EOS models used to simulate integrated ICF experiments indicates the need for an improved multiphase EOS model for HDC in order to achieve a significant increase in neutron yield in indirect-driven ICF implosions with HDC ablators.

Measuring the shock impedance mismatch between high-density carbon and deuterium at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Millot, M.; Celliers, P. M.; Sterne, P. A.

Fine-grained diamond, or high-density carbon (HDC), is being used as an ablator for inertial confinement fusion (ICF) research at the National Ignition Facility (NIF). Accurate equation of state (EOS) knowledge over a wide range of phase space is critical in the design and analysis of integrated ICF experiments. Here in this paper, we report shock and release measurements of the shock impedance mismatch between HDC and liquid deuterium conducted during shock-timing experiments having a first shock in the ablator ranging between 8 and 14 Mbar. Using ultrafast Doppler imaging velocimetry to track the leading shock front, we characterize the shockmore » velocity discontinuity upon the arrival of the shock at the HDC/liquid deuterium interface. Comparing the experimental data with tabular EOS models used to simulate integrated ICF experiments indicates the need for an improved multiphase EOS model for HDC in order to achieve a significant increase in neutron yield in indirect-driven ICF implosions with HDC ablators.« less

Critical Science Issues for Direct Drive Inertial Fusion Energy

NASA Astrophysics Data System (ADS)

Dahlburg, Jill P.; Gardner, John H.; Schmitt, Andrew J.; Obenschain, S. P.

1998-09-01

There are several topics that require resolution prior to the construction of an Inertial Fusion Energy [IFE] laboratory Engineering Test Facility [ETF]: a pellet that produces high gain; a pellet fabrication system that cost-effectively and rapidly manufactures these pellets; a sufficiently uniform and durable high repetition-rate laser pellet driver; a practical target injection system that provides accurate pellet aiming; and, a target chamber that will survive the debris and radiation of repeated high-gain pellet implosions. In this summary we describe the science issues and opportunities that are involved in the design of a successful high gain direct drive Inertial Confinement Fusion [ICF] pellet.

Approximate models for the ion-kinetic regime in inertial-confinement-fusion capsule implosions

DOE PAGES

Hoffman, Nelson M.; Zimmerman, George B.; Molvig, Kim; ...

2015-05-19

“Reduced” (i.e., simplified or approximate) ion-kinetic (RIK) models in radiation-hydrodynamic simulations permit a useful description of inertial-confinement-fusion (ICF) implosions where kinetic deviations from hydrodynamic behavior are important. For implosions in or near the kinetic regime (i.e., when ion mean free paths are comparable to the capsule size), simulations using a RIK model give a detailed picture of the time- and space-dependent structure of imploding capsules, allow an assessment of the relative importance of various kinetic processes during the implosion, enable explanations of past and current observations, and permit predictions of the results of future experiments. The RIK simulation method describedmore » here uses moment-based reduced kinetic models for transport of mass, momentum, and energy by long-mean-free-path ions, a model for the decrease of fusion reactivity owing to the associated modification of the ion distribution function, and a model of hydrodynamic turbulent mixing. Transport models are based on local gradient-diffusion approximations for the transport of moments of the ion distribution functions, with coefficients to impose flux limiting or account for transport modification. After calibration against a reference set of ICF implosions spanning the hydrodynamic-to-kinetic transition, the method has useful, quantifiable predictive ability over a broad range of capsule parameter space. Calibrated RIK simulations show that an important contributor to ion species separation in ICF capsule implosions is the preferential flux of longer-mean-free-path species out of the fuel and into the shell, leaving the fuel relatively enriched in species with shorter mean free paths. Also, the transport of ion thermal energy is enhanced in the kinetic regime, causing the fuel region to have a more uniform, lower ion temperature, extending over a larger volume, than implied by clean simulations. Furthermore, we expect that the success of our simple approach will motivate continued theoretical research into the development of first-principles-based, comprehensive, self-consistent, yet useable models of kinetic multispecies ion behavior in ICF plasmas.« less

Ignition and pusher adiabat

DOE PAGES

Cheng, B. L.; Kwan, T. J. T.; Wang, Y. M.; ...

2018-05-18

In the last five years, large amounts of high quality experimental data in inertial confinement fusion (ICF) were produced at the National Ignition Facility (NIF). From the NIF data, we have significantly advanced our scientific understanding of the physics of thermonuclear (TN) ignition in ICF and identified the critical physical issues important to achieve ignition, such as implosion energetics, pusher adiabat, tamping effects in fuel confinement, and confinement time. In this article, we will present recently developed TN ignition theory and implosion scaling laws [1, 2] characterizing the thermodynamic properties of the hot spot and the TN ignition metrics atmore » NIF. We compare our theoretical predictions with NIF data with good agreement between theory and experiments. We will also demonstrate the fundamental effects of the pusher adiabat on the energy partition between the cold shell and the hot deuterium-tritium and on the neutron yields of ICF capsules. Applications [3–5] to NIF experiments and physical explanations of the discrepancies among theory, data and simulations will be presented. In our theory, the actual adiabat of the cold DT fuel can be inferred from neutron image data of a burning capsule. With the experimentally inferred hot spot mix, the CH mix in the cold fuel could be estimated, as well as the preheat. Finally, possible path forwards to reach high yields are discussed.« less

Multiscale Modeling of Ionospheric Irregularities

DTIC Science & Technology

2014-10-22

REPORT TYPE 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER...Taylor (RT) instabilities, occurs in settings that are as varied as exploding stars (supernovae), inertial confinement fusion (ICF) and macroscopic...These global models, together with the large observational data sets that have been accu- mulated over the years, have led to a much greater under

NRL Review 2005. Pioneering the Future

DTIC Science & Technology

2005-01-01

pulse high- intensity lasers —the Table-Top Terawatt (T3) laser and the new Ti:Sapphire Femtosecond Laser (TFL)—to study intense laser -plasma...56 laser beams and is single- pulsed (4-ns pulse ). This facility provides intense radiation for studying inertial confinement fusion (ICF) target... ultrashort - pulse (40 fs), Ti:Sapphire Fem- tosecond Laser (TFL) system is now operational at 1 TW. These lasers comprise a

Imaging Research With Non-Periodic Multilayers for Inertial Confinement Fusion Diagnostic Experiments

NASA Astrophysics Data System (ADS)

L. Wang, F.; Mu, B. Z.; Wang, Z. S.; Gu, C. S.; Zhang, Z.; Qin, S. J.; Chen, L. Y.

A grazing Kirkpatrick-Baez (K-B) microscope was designed for hard x-ray (8keV; Cu Ka radiation) imaging in Inertial Confinement Fusion (ICF) diagnostic experiments. Ray tracing software was used to simulate optical system performance. The optimized theoretical resolution of K-B microscope was about 2 micron and better than 10 micron in 200 micron field of view. Tungsten and boron carbide were chosen as multilayer materials and the multilayer was deposited onto the silicon wafer substrate and the reflectivity was measured by x-ray diffraction (XRD). The reflectivity of supermirror was about 20 % in 0.3 % of bandwidth. 8keV Cu target x-ray tube source was used in x-ray imaging experiments and the magnification of 1x and 2x x-ray images were obtained.

Fluorescence and absorption spectroscopy for warm dense matter studies and ICF plasma diagnostics

NASA Astrophysics Data System (ADS)

Hansen, Stephanie

2017-10-01

The burning core of an inertial confinement fusion (ICF) plasma at stagnation is surrounded by a shell of warm, dense matter whose properties are difficult both to model (due to a complex interplay of thermal, degeneracy, and strong coupling effects) and to diagnose (due to low emissivity and high opacity). We demonstrate a promising technique to study the warm dense shells of ICF plasmas based on the fluorescence emission of dopants or impurities in the shell material. This emission, which is driven by x-rays produced in the hot core, exhibits signature changes in response to compression and heating. High-resolution measurements of absorption and fluorescence features can refine our understanding of the electronic structure of material under high compression, improve our models of density-driven phenomena such as ionization potential depression and plasma polarization shifts, and help diagnose shell density, temperature, mass distribution, and residual motion in ICF plasmas at stagnation. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA-0003525. This work was supported by the U.S. Department of Energy, Office of Science Early Career Research Program, Office of Fusion Energy Sciences under FWP-14-017426.

The effect of turbulent kinetic energy on inferred ion temperature from neutron spectra

NASA Astrophysics Data System (ADS)

Murphy, T. J.

2014-07-01

Measuring the width of the energy spectrum of fusion-produced neutrons from deuterium (DD) or deuterium-tritium (DT) plasmas is a commonly used method for determining the ion temperature in inertial confinement fusion (ICF) implosions. In a plasma with a Maxwellian distribution of ion energies, the spread in neutron energy arises from the thermal spread in the center-of-mass velocities of reacting pairs of ions. Fluid velocities in ICF are of a similar magnitude as the center-of-mass velocities and can lead to further broadening of the neutron spectrum, leading to erroneous inference of ion temperature. Motion of the reacting plasma will affect DD and DT neutrons differently, leading to disagreement between ion temperatures inferred from the two reactions. This effect may be a contributor to observations over the past decades of ion temperatures higher than expected from simulations, ion temperatures in disagreement with observed yields, and different temperatures measured in the same implosion from DD and DT neutrons. This difference in broadening of DD and DT neutrons also provides a measure of turbulent motion in a fusion plasma.

A dual-PIXE tomography setup for reconstruction of Germanium in ICF target

NASA Astrophysics Data System (ADS)

Guo, N.; Lu, H. Y.; Wang, Q.; Meng, J.; Gao, D. Z.; Zhang, Y. J.; Liang, X. X.; Zhang, W.; Li, J.; Ma, X. J.; Shen, H.

2017-08-01

Inertial Confinement Fusion (ICF) is one type of fusion energy research which could initiate nuclear fusion reactions through heating and compressing thermonuclear fuel. Compared to a pure plastic target, Germanium doping into the CH ablator layer by Glow Discharge Polymer (GDP) technique can increase the ablation velocity and the standoff distance between the ablation front and laser-deposition region. During target fabrication process, quantitative doping of Ge should be accurately controlled. Particle Induced X-ray Emission Tomography (PIXE-T) can make not only quantification of the concentration, but also reconstruction of the spatial distribution of doped element. The Si (Li) detector for PIXE tomography technique had a disadvantage of low counting rate. To make up this deficiency, another detector of Si (Li) with the same configuration positioned at the opposite side with the same detective angle 135° have been implemented. Simultaneously acquired elemental maps of Ge obtained using two detectors may be different because of the X-ray absorption along the X-ray exit route in the target. In this paper, the X-ray detection efficiency is drastically improved by this dual-PIXE tomography system.

Fusion-neutron-yield, activation measurements at the Z accelerator: design, analysis, and sensitivity.

PubMed

Hahn, K D; Cooper, G W; Ruiz, C L; Fehl, D L; Chandler, G A; Knapp, P F; Leeper, R J; Nelson, A J; Smelser, R M; Torres, J A

2014-04-01

We present a general methodology to determine the diagnostic sensitivity that is directly applicable to neutron-activation diagnostics fielded on a wide variety of neutron-producing experiments, which include inertial-confinement fusion (ICF), dense plasma focus, and ion beam-driven concepts. This approach includes a combination of several effects: (1) non-isotropic neutron emission; (2) the 1/r(2) decrease in neutron fluence in the activation material; (3) the spatially distributed neutron scattering, attenuation, and energy losses due to the fielding environment and activation material itself; and (4) temporally varying neutron emission. As an example, we describe the copper-activation diagnostic used to measure secondary deuterium-tritium fusion-neutron yields on ICF experiments conducted on the pulsed-power Z Accelerator at Sandia National Laboratories. Using this methodology along with results from absolute calibrations and Monte Carlo simulations, we find that for the diagnostic configuration on Z, the diagnostic sensitivity is 0.037% ± 17% counts/neutron per cm(2) and is ∼ 40% less sensitive than it would be in an ideal geometry due to neutron attenuation, scattering, and energy-loss effects.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2013-09-27

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”more » (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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2013-09-15

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”more » (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.« less

A study of thermal hydraulic and kinetic phenomena in HYLIFE-2: An inertial confinement fusion reactor

NASA Astrophysics Data System (ADS)

Chen, Xiang Ming

1993-01-01

Researchers have studied the different aspects of commercial fusion energy for several decades. A variety of inertial confinement fusion (ICF) reactors have been proposed. Different from the magnetic confinement fusion concept, inertial confinement fusion does not need long-term confinement of the fusion fuel but achieves fusion reaction in a short microexplosion under a high density, high temperature condition. The HYLIFE-2 reactor design started in 1987 is based on the study of a previous concept called HYLIFE (High Yield Lithium Injection Fusion Energy). Similar to the old concept, the HYLIFE-2 design uses a vacuum chamber in which D-T fusion pellets are injected and ignited by high energy beams shot into the reactor through different ports. The reactor vessel is protected from explosion radiations by a liquid fall (blanket) that also breeds tritium through the (n, alpha) reaction of lithium and conveys the fusion energy to the power cycle. In addition to some geometric chances, the new design replaces liquid metal lithium with the molten salt Flibe (Li2BeF4) as the protective blanket material. The objective was to remove the possibility of fire hazard. The important thermal hydraulic issues in the design are (1) equation of state of Flibe; (2) liquid relaxation after isochoric (constant volume) heating; (3) ablation and gas dynamics; (4) interaction of the vapor and liquid; and (5) condensation of the vaporized material. The first four issues have to do with the internal relaxation after the fusion microexplosion in the chamber. Vaporized material, as well as liquid, may assert strong impulses on the chamber wall during the process of relaxing after absorbing the energy from the microexplosion. Item (5) is related to the rapid vacuum recovery between the ignitions. Some aspects of the first four issues are studied.

Transparent electrode for optical switch

DOEpatents

Goldhar, J.; Henesian, M.A.

1984-10-19

The invention relates generally to optical switches and techniques for applying a voltage to an electro-optical crystal, and more particularly, to transparent electodes for an optical switch. System architectures for very large inertial confinement fusion (ICF) lasers require active optical elements with apertures on the order of one meter. Large aperture optical switches are needed for isolation of stages, switch-out from regenerative amplifier cavities and protection from target retroreflections.

On the transport coefficients of hydrogen in the inertial confinement fusion regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambert, Flavien; Recoules, Vanina; Decoster, Alain

2011-05-15

Ab initio molecular dynamics is used to compute the thermal and electrical conductivities of hydrogen from 10 to 160 g cm{sup -3} and temperatures up to 800 eV, i.e., thermodynamical conditions relevant to inertial confinement fusion (ICF). The ionic structure is obtained using molecular dynamics simulations based on an orbital-free treatment for the electrons. The transport properties were computed using ab initio simulations in the DFT/LDA approximation. The thermal and electrical conductivities are evaluated using Kubo-Greenwood formulation. Particular attention is paid to the convergence of electronic transport properties with respect to the number of bands and atoms. These calculations aremore » then used to check various analytical models (Hubbard's, Lee-More's and Ichimaru's) widely used in hydrodynamics simulations of ICF capsule implosions. The Lorenz number, which is the ratio between thermal and electrical conductivities, is also computed and compared to the well-known Wiedemann-Franz law in different regimes ranging from the highly degenerate to the kinetic one. This allows us to deduce electrical conductivity from thermal conductivity for analytical model. We find that the coupling of Hubbard and Spitzer models gives a correct description of the behavior of electrical and thermal conductivities in the whole thermodynamic regime.« less

D-Cluster Converter Foil for Laser-Accelerated Deuteron Beams: Towards Deuteron-Beam-Driven Fast Ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miley, George H.

Fast Ignition (FI) uses Petawatt laser generated particle beam pulse to ignite a small volume called a pre-compressed Inertial Confinement Fusion (ICF) target, and is the favored method to achieve the high energy gain per target burn needed for an attractive ICF power plant. Ion beams such as protons, deuterons or heavier carbon ions are especially appealing for FI as they have relative straight trajectory, and easier to focus on the fuel capsule. But current experiments have encountered problems with the 'converter-foil' which is irradiated by the Petawatt laser to produce the ion beams. The problems include depletion of themore » available ions in the convertor foils, and poor energy efficiency (ion beam energy/ input laser energy). We proposed to develop a volumetrically-loaded ultra-high-density deuteron deuterium cluster material as the basis for converter-foil for deuteron beam generation. The deuterons will fuse with the ICF DT while they slow down, providing an extra 'bonus' energy gain in addition to heating the hot spot. Also, due to the volumetric loading, the foil will provide sufficient energetic deuteron beam flux for 'hot spot' ignition, while avoiding the depletion problem encountered by current proton-driven FI foils. After extensive comparative studies, in Phase I, high purity PdO/Pd/PdO foils were selected for the high packing fraction D-Cluster converter foils. An optimized loading process has been developed to increase the cluster packing fraction in this type of foil. As a result, the packing fraction has been increased from 0.1% to 10% - meeting the original Phase I goal and representing a significant progress towards the beam intensities needed for both FI and pulsed neutron applications. Fast Ignition provides a promising approach to achieve high energy gain target performance needed for commercial Inertial Confinement Fusion (ICF). This is now a realistic goal for near term in view of the anticipated ICF target burn at the National Ignition Facility (NIF) in CA within a year. This will usher in the technology development Phase of ICF after years of research aimed at achieving breakeven experiment. Methods to achieve the high energy gain needed for a competitive power plant will then be a key developmental issue, and our D-cluster target for Fast Ignition (FI) is expected to meet that need.« less

Damage mechanisms avoided or managed for NIF large optics

DOE PAGES

Manes, K. R.; Spaeth, M. L.; Adams, J. J.; ...

2016-02-09

After every other failure mode has been considered, in the end, the high-performance limit of all lasers is set by optical damage. The demands of inertial confinement fusion (ICF) pushed lasers designed as ICF drivers into this limit from their very earliest days. The first ICF lasers were small, and their pulses were short. Their goal was to provide as much power to the target as possible. Typically, they faced damage due to high intensity on their optics. As requests for higher laser energy, longer pulse lengths, and better symmetry appeared, new kinds of damage also emerged, some of themmore » anticipated and others unexpected. This paper will discuss the various types of damage to large optics that had to be considered, avoided to the extent possible, or otherwise managed as the National Ignition Facility (NIF) laser was designed, fabricated, and brought into operation. Furthermore, it has been possible for NIF to meet its requirements because of the experience gained in previous ICF systems and because NIF designers have continued to be able to avoid or manage new damage situations as they have appeared.« less

First Measurements of Deuterium-Tritium and Deuterium-Deuterium Fusion Reaction Yields in Ignition-Scalable Direct-Drive Implosions

NASA Astrophysics Data System (ADS)

Forrest, C. J.; Radha, P. B.; Knauer, J. P.; Glebov, V. Yu.; Goncharov, V. N.; Regan, S. P.; Rosenberg, M. J.; Sangster, T. C.; Shmayda, W. T.; Stoeckl, C.; Gatu Johnson, M.

2017-03-01

The deuterium-tritium (D-T) and deuterium-deuterium neutron yield ratio in cryogenic inertial confinement fusion (ICF) experiments is used to examine multifluid effects, traditionally not included in ICF modeling. This ratio has been measured for ignition-scalable direct-drive cryogenic DT implosions at the Omega Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997), 10.1016/S0030-4018(96)00325-2] using a high-dynamic-range neutron time-of-flight spectrometer. The experimentally inferred yield ratio is consistent with both the calculated values of the nuclear reaction rates and the measured preshot target-fuel composition. These observations indicate that the physical mechanisms that have been proposed to alter the fuel composition, such as species separation of the hydrogen isotopes [D. T. Casey et al., Phys. Rev. Lett. 108, 075002 (2012), 10.1103/PhysRevLett.108.075002], are not significant during the period of peak neutron production in ignition-scalable cryogenic direct-drive DT implosions.

Design options for reducing the impact of the fill-tube in ICF implosion experiments on the NIF

NASA Astrophysics Data System (ADS)

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.

Two-plasmon decay mitigation in direct-drive inertial-confinement-fusion experiments using multilayer targets

DOE PAGES

Follett, R. K.; Delettrez, J. A.; Edgell, D. H.; ...

2016-04-15

Multilayer direct-drive inertial-confinement-fusion (ICF) targets are shown to significantly reduce two-plasmon-decay (TPD) driven hot-electron production while maintaining high hydrodynamic efficiency. Implosion experiments on the OMEGA Laser used targets with silicon layered between an inner beryllium and outer silicon-doped plastic ablator. A factor of five reduction in hot-electron generation (> 50 keV) was observed in the multilayer targets relative to pure CH targets. Three-dimensional simulations of the TPD driven hot-electron production using a laser-plasma interaction code (LPSE) that includes nonlinear and kinetic effects show excellent agreement with the measurements. As a result, the simulations suggest that the reduction in hot-electron productionmore » observed in the multilayer targets is primarily due to increased electron-ion collisional damping.« less

Ablative Rayleigh Taylor instability in the limit of an infinitely large density ratio

NASA Astrophysics Data System (ADS)

Clavin, Paul; Almarcha, Christophe

2005-05-01

The instability of ablation fronts strongly accelerated toward the dense medium under the conditions of inertial confinement fusion (ICF) is addressed in the limit of an infinitely large density ratio. The analysis serves to demonstrate that the flow is irrotational to first order, reducing the nonlinear analysis to solve a two-potential flows problem. Vorticity appears at the following orders in the perturbation analysis. This result simplifies greatly the analysis. The possibility for using boundary integral methods opens new perspectives in the nonlinear theory of the ablative RT instability in ICF. A few examples are given at the end of the Note. To cite this article: P. Clavin, C. Almarcha, C. R. Mecanique 333 (2005).

Proceedings of the twelfth target fabrication specialists` meeting

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1999-04-01

Research in fabrication for inertial confinement fusion (ICF) comprises at least three broad categories: targets for high energy density physics on existing drivers, ignition capsule fabrication, and cryogenic fuel layer formation. The latter two are being pursued primarily for the National Ignition Facility (NIF). Scientists from over 14 laboratories, universities, and businesses contributed over 100 papers on all aspects of ICF target fabrication. The NIF is well along in construction and photos of poured concrete and exposed steel added to the technical excitement. It was clear from the meeting that there has been significant progress toward the fabrication of anmore » ignition target for NIF and that new techniques are resulting in higher quality targets for high energy density research.« less

Elucidation of the Dynamics for Hot-Spot Initiation at Nonuniform Interfaces of Highly Shocked Materials

DTIC Science & Technology

2011-12-07

with nonuniform interfaces plays an essential role in the interfacial instabilities in iner- tial confinement fusion (ICF), in shock-induced...involved in interfacial instabilities at the atomic scale, providing insights on such phenomenon. Thus ReaxFF provides the possibility of realistic...calculations was also performed on the IPDI and DOA to determine the charges and structures for the binder model. These QM results and model preparation

Elucidation of the Dynamics for Hot-Spot Initiation at Nonuniform Interfaces of Highly Shocked Materials

DTIC Science & Technology

2011-12-07

with nonuniform interfaces plays an essential role in the interfacial instabilities in iner- tial confinement fusion (ICF), in shock-induced...involved in interfacial instabilities at the atomic scale, providing insights on such phenomenon. Thus ReaxFF provides the possibility of realistic...on the IPDI and DOA to determine the charges and structures for the binder model. These QM results and model preparation procedure are provided as part

Observation of Interspecies Ion Separation in Inertial-Confinement-Fusion Implosions via Imaging X-ray spectroscopy

NASA Astrophysics Data System (ADS)

Joshi, Tirtha Raj

2016-10-01

Interspecies ion separation has been proposed as a yield-degradation mechanism in inertial-confinement-fusion (ICF) experiments. We present direct experimental evidence of interspecies ion separation in direct-drive ICF experiments performed at the OMEGA laser facility. These experiments were designed based on the fact that interspecies ion thermo-diffusion would be strongest for species with large mass and charge difference. The targets were spherical plastic shells filled with D2 and Ar (1% by atom). Ar K-shell spectral features were observed primarily between the time of first-shock convergence and slightly before neutron bang time, using a time- and space-integrated spectrometer, streaked crystal spectrometer, and two gated multi-monochromatic X-ray imagers fielded along quasi-orthogonal lines-of-sight. Detailed spectroscopic analyses of spatially resolved Ar K-shell lines reveal deviation from the initial 1%-Ar gas fill and show both Ar-concentration enhancement and depletion at different times and radial positions of the implosion. The experimental results are interpreted with radiation-hydrodynamic simulations that include recently implemented, first-principles models of interspecies ion diffusion. The experimentally inferred Ar-atom-fraction profiles agree gently with calculated profiles associated with the incoming and rebounding first shock. This work was done in collaboration with P. Hakel, S. C. Hsu, E. L. Vold, M. J. Schmitt, N. M. Hoffman, R. M. Rauenzahn, G. Kagan, X.-Z. Tang, Y. Kim, and H. W. Herrmann of LANL, and R. C. Mancini of UNR. LA-UR-16-24804. Supported by the LANL ICF and ASC Programs under US-DoE contract no. DE-AC52-06NA25396.

Luminescence in the fluoride-containing phosphate-based glasses: A possible origin of their high resistance to nanosecond pulse laser-induced damage

PubMed Central

Wang, Pengfei; Lu, Min; Gao, Fei; Guo, Haitao; Xu, Yantao; Hou, Chaoqi; Zhou, Zhiwei; Peng, Bo

2015-01-01

Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers. PMID:25716328

Luminescence in the fluoride-containing phosphate-based glasses: a possible origin of their high resistance to nanosecond pulse laser-induced damage.

PubMed

Wang, Pengfei; Lu, Min; Gao, Fei; Guo, Haitao; Xu, Yantao; Hou, Chaoqi; Zhou, Zhiwei; Peng, Bo

2015-02-26

Fusion power offers the prospect of an almost inexhaustible source of energy for future generations. It was reported that fusion fuel gains exceeding unity on the National Ignition Facility (NIF) were achieved, but so far great deal of scientific and engineering challenges have to be overcome for realizing fusion power generation. There is a bottleneck for color-separation gratings in NIF and other similar inertial confinement fusion (ICF) lasers. Here we show a series of high performance phosphate-based glasses that can transmit the third harmonic frequency (3ω) laser light with high efficiency meanwhile filter the fundamental (1ω) and the second harmonic frequency (2ω) laser lights through direct absorption, and especially they exhibit excellent damage threshold induced by nanosecond pulse laser compared with that of the fused silica used in NIF. Yellowish-orange fluorescence emits during the laser-material interaction process, and it can be tailored through regulating the glass structure. Study on its structural origin suggests that the fluorescence emission is a key factor that conduces to the high laser-induced damage resistance of these glasses. The results also indicated the feasibility of utilizing these high performance glasses in novel color separation optics, allowing novel design for the final optics assembly in ICF lasers.

Fast Pb-glass neutron-to-light converter for ICF (Inertial Confinement Fusion) target burn history measurements

NASA Astrophysics Data System (ADS)

Lerche, R. A.; Cable, M. D.; Phillion, D. W.

1990-09-01

We are developing a streak camera based instrument to diagnose the fusion reaction rate (burn history) within laser-driven ICF targets filled with D-T fuel. Recently, we attempted measurements using the 16.7 MeV gamma ray emitted in the T(d,gamma)He(5) fusion reaction. Pb glass which has a large cross section for pair production acts as a gamma-ray-to-light converter. Gamma rays interact within the glass to form electron-positron pairs that produce large amounts (1000 photons/gamma ray) of prompt (less than 10 ps) Cerenkov light as they slow down. In our experimental instrument, an f/10 Cassegrain telescope optically couples light produced within the converter to a streak camera having 20-ps resolution. Experiments using high-yield (10(exp 13) D-T neutrons), direct-drive targets at Nova produced good signals with widths of 200 ps. Time-of-flight measurements show the signals to be induced by neutrons rather than gamma rays. The Pb glass appears to act as a fast neutron-to-light converter. We continue to study the interactions process and the possibility of using the 16.7 MeV gamma rays for burn time measurements.

Preface: Twenty-First Target Fabrication Specialists Meeting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikroo, Abbas; Czechowicz, Don

The Twenty First Target Fabrication Meeting held in Las Vegas, Nevada, from June xx-yy 2015, was attended by more than 100 scientists, engineers, and technicians from the United States, the United Kingdom, France, and Japan, bringing together international experts on the design, development, and fabrication of inertial confinement fusion (ICF) and high-energy-density (HED) experimental targets fielded on laser and pulsed-power facilities around the world. We were delighted to have such exceptional international representation. The program included 4 invited papers, 53 contributed papers, and 55 posters. A selection of these is presented in this dedicated issue of Fusion Science and Technologymore » (FST).« less

Preface: Twenty-First Target Fabrication Specialists Meeting

DOE PAGES

Nikroo, Abbas; Czechowicz, Don

2017-04-21

The Twenty First Target Fabrication Meeting held in Las Vegas, Nevada, from June xx-yy 2015, was attended by more than 100 scientists, engineers, and technicians from the United States, the United Kingdom, France, and Japan, bringing together international experts on the design, development, and fabrication of inertial confinement fusion (ICF) and high-energy-density (HED) experimental targets fielded on laser and pulsed-power facilities around the world. We were delighted to have such exceptional international representation. The program included 4 invited papers, 53 contributed papers, and 55 posters. A selection of these is presented in this dedicated issue of Fusion Science and Technologymore » (FST).« less

Non-critical phase-matching fourth harmonic generation of a 1053-nm laser in an ADP crystal

PubMed Central

Ji, Shaohua; Wang, Fang; Zhu, Lili; Xu, Xinguang; Wang, Zhengping; Sun, Xun

2013-01-01

In current inertial confinement fusion (ICF) facilities, KDP and DKDP crystals are the second harmonic generation (SHG) and third harmonic generation (THG) materials for the Nd:glass laser (1053 nm). Based on the trend for the development of short wavelengths for ICF driving lasers, technical solutions for fourth harmonic generation (FHG) will undoubtedly attract more and more attention. In this paper, the rapid growth of an ADP crystal and non-critical phase-matching (NCPM) FHG of a 1053-nm laser using an ADP crystal are reported. The NCPM temperature is 33.7°C. The conversion efficiency from 526 to 263 nm is 70%, and the angular acceptance range is 55.4 mrad; these results are superior to those for the DKDP crystals. This research has shown that ADP crystals will be a competitive candidate in future ICF facilities when the utilisation of high-energy, high-efficiency UV lasers at wavelengths shorter than the present 351 nm is of interest. PMID:23549389

Non-critical phase-matching fourth harmonic generation of a 1053-nm laser in an ADP crystal.

PubMed

Ji, Shaohua; Wang, Fang; Zhu, Lili; Xu, Xinguang; Wang, Zhengping; Sun, Xun

2013-01-01

In current inertial confinement fusion (ICF) facilities, KDP and DKDP crystals are the second harmonic generation (SHG) and third harmonic generation (THG) materials for the Nd:glass laser (1053 nm). Based on the trend for the development of short wavelengths for ICF driving lasers, technical solutions for fourth harmonic generation (FHG) will undoubtedly attract more and more attention. In this paper, the rapid growth of an ADP crystal and non-critical phase-matching (NCPM) FHG of a 1053-nm laser using an ADP crystal are reported. The NCPM temperature is 33.7°C. The conversion efficiency from 526 to 263 nm is 70%, and the angular acceptance range is 55.4 mrad; these results are superior to those for the DKDP crystals. This research has shown that ADP crystals will be a competitive candidate in future ICF facilities when the utilisation of high-energy, high-efficiency UV lasers at wavelengths shorter than the present 351 nm is of interest.

Development of aerogel-lined targets for inertial confinement fusion experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braun, Tom

2013-03-28

This thesis explores the formation of ICF compatible foam layers inside of an ablator shell used for inertial confinement fusion experiments at the National Ignition Facility. In particular, the capability of p- DCPD polymer aerogels to serve as a scaffold for the deuterium-tritium mix was analyzed. Four different factors were evaluated: the dependency of different factors such as thickness or composition of a precursor solution on the uniformity of the aerogel layer, how to bring the optimal composition inside of the ablator shell, the mechanical stability of ultra-low density p-DCPD aerogel bulk pieces during wetting and freezing with hydrogen, andmore » the wetting behavior of thin polymer foam layers in HDC carbon ablator shells with liquid deuterium. The research for thesis was done at Lawrence Livermore National Laboratory in cooperation with the Technical University Munich.« less

Inhibition of turbulence in inertial-confinement-fusion hot spots by viscous dissipation.

PubMed

Weber, C R; Clark, D S; Cook, A W; Busby, L E; Robey, H F

2014-05-01

Achieving ignition in inertial confinement fusion (ICF) requires the formation of a high-temperature (>10 keV) central hot spot. Turbulence has been suggested as a mechanism for degrading the hot-spot conditions by altering transport properties, introducing colder, mixed material, or reducing the conversion of radially directed kinetic energy to hot-spot heating. We show, however, that the hot spot is very viscous, and the assumption of turbulent conditions in the hot spot is incorrect. This work presents the first high-resolution, three-dimensional simulations of National Ignition Facility (NIF) implosion experiments using detailed knowledge of implosion dynamics and instability seeds and including an accurate model of physical viscosity. We find that when viscous effects are neglected, the hot spot can exhibit a turbulent kinetic energy cascade. Viscous effects, however, are significant and strongly damp small-scale velocity structures, with a hot-spot Reynolds number in the range of only 10-100.

Inhibition of turbulence in inertial-confinement-fusion hot spots by viscous dissipation

NASA Astrophysics Data System (ADS)

Weber, C. R.; Clark, D. S.; Cook, A. W.; Busby, L. E.; Robey, H. F.

2014-05-01

Achieving ignition in inertial confinement fusion (ICF) requires the formation of a high-temperature (>10 keV) central hot spot. Turbulence has been suggested as a mechanism for degrading the hot-spot conditions by altering transport properties, introducing colder, mixed material, or reducing the conversion of radially directed kinetic energy to hot-spot heating. We show, however, that the hot spot is very viscous, and the assumption of turbulent conditions in the hot spot is incorrect. This work presents the first high-resolution, three-dimensional simulations of National Ignition Facility (NIF) implosion experiments using detailed knowledge of implosion dynamics and instability seeds and including an accurate model of physical viscosity. We find that when viscous effects are neglected, the hot spot can exhibit a turbulent kinetic energy cascade. Viscous effects, however, are significant and strongly damp small-scale velocity structures, with a hot-spot Reynolds number in the range of only 10--100.

Refraction-enhanced backlit imaging of axially symmetric inertial confinement fusion plasmas.

PubMed

Koch, Jeffrey A; Landen, Otto L; Suter, Laurence J; Masse, Laurent P; Clark, Daniel S; Ross, James S; Mackinnon, Andrew J; Meezan, Nathan B; Thomas, Cliff A; Ping, Yuan

2013-05-20

X-ray backlit radiographs of dense plasma shells can be significantly altered by refraction of x rays that would otherwise travel straight-ray paths, and this effect can be a powerful tool for diagnosing the spatial structure of the plasma being radiographed. We explore the conditions under which refraction effects may be observed, and we use analytical and numerical approaches to quantify these effects for one-dimensional radial opacity and density profiles characteristic of inertial-confinement fusion (ICF) implosions. We also show how analytical and numerical approaches allow approximate radial plasma opacity and density profiles to be inferred from point-projection refraction-enhanced radiography data. This imaging technique can provide unique data on electron density profiles in ICF plasmas that cannot be obtained using other techniques, and the uniform illumination provided by point-like x-ray backlighters eliminates a significant source of uncertainty in inferences of plasma opacity profiles from area-backlit pinhole imaging data when the backlight spatial profile cannot be independently characterized. The technique is particularly suited to in-flight radiography of imploding low-opacity shells surrounding hydrogen ice, because refraction is sensitive to the electron density of the hydrogen plasma even when it is invisible to absorption radiography. It may also provide an alternative approach to timing shockwaves created by the implosion drive, that are currently invisible to absorption radiography.

Statistical Relations for Yield Degradation in Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Woo, K. M.; Betti, R.; Patel, D.; Gopalaswamy, V.

2017-10-01

In inertial confinement fusion (ICF), the yield-over-clean (YOC) is a quantity commonly used to assess the performance of an implosion with respect to the degradation caused by asymmetries. The YOC also determines the Lawson parameter used to identify the onset of ignition and the level of alpha heating in ICF implosions. In this work, we show that the YOC is a unique function of the residual kinetic energy in the compressed shell (with respect to the 1-D case) regardless of the asymmetry spectrum. This result is derived using a simple model of the deceleration phase as well as through an extensive set of 3-D radiation-hydrodynamics simulations using the code DEC3D. The latter has been recently upgraded to include a 3-D spherical moving mesh, the HYPRE solver for 3-D radiation transport and piecewise-parabolic method for robust shock-capturing hydrodynamic simulations. DEC3D is used to build a synthetic single-mode database to study the behavior of yield degradation caused by Rayleigh-Taylor instabilities in the deceleration phase. The relation between YOC and residual kinetic energy is compared with the result in an adiabatic implosion model. The statistical expression of YOC is also applied to the ignition criterion in the presence of multidimensional nonuniformities. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Improved AFM Mapping of ICF Target Surfaces

NASA Astrophysics Data System (ADS)

Olson, D. K.; Drake, T.; Frey, D.; Huang, H.; Stephens, R. B.

2003-10-01

Targets for Inertial Confinement Fusion (ICF) research are made from spherical shells with very strict requirements on surface smoothness. Hydrodynamic instabilities are amplified by the presence of surface defects, greatly reducing the gain of ICF targets. Sub-micron variations in the surface can be examined using an Atomic Force Microscope. The current sphere mapping assembly at General Atomics is designed to trace near the equator of a rotating sphere under the AFM head. Spheres are traced on three mutually orthogonal planes. The ˜10 mm piezo-electric actuator range limits how far off the equator we can scan spheres of millimeter diameter. Because only a small fraction of the target's surface can be covered, localized high-mode defects are difficult to detect. In order to meet the needs of ICF research, we need to scan more surface area of the sphere with the AFM. By integrating an additional stepping motor to the sphere mapping assembly, we will be able to recenter the piezo driver of the AFM while mapping. This additional ability allows us to increase the amount of the sphere's surface we are able to scan with the AFM by extending the range of the AFM from the sphere's equator.

Ion kinetic dynamics in strongly-shocked plasmas relevant to ICF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinderknecht, H. G.; Amendt, P. A.; Rosenberg, M. J.

Implosions of thin-shell capsules produce strongly-shocked (M > 10), low-density (ρ ~1 mg/cc -1), high-temperature (T i ~keV) plasmas, comparable to those produced in the strongly-shocked DT-vapor in inertial confinement fusion (ICF) experiments. A series of thin-glass targets filled with mixtures of deuterium and Helium-3 gas ranging from 7% to 100% deuterium was imploded to investigate the impact of multi-species ion kinetic mechanisms in ICF-relevant plasmas over a wide range of Knudsen numbers (N K ≡ λ ii/R). Anomalous trends in nuclear yields and burn-averaged ion temperatures in implosions with N K > 0.5, which have been interpreted as signaturesmore » of ion species separation and ion thermal decoupling, are found not to be consistent with single-species ion kinetic effects alone. Experimentally inferred Knudsen numbers predict an opposite yield trend to those observed, confirming the dominance of multi-species physics in these experiments. In contrast, implosions with N K ~ 0.01 follow the expected yield trend, suggesting single-species kinetic effects are dominant. In conclusion, the impact of the observed kinetic physics mechanisms on the formation of the hotspot in ICF experiments is discussed.« less

Kinetic physics in ICF: present understanding and future directions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinderknecht, Hans G.; Amendt, P. A.; Wilks, S. C.

Kinetic physics has the potential to impact the performance of indirect-drive inertial confinement fusion (ICF) experiments. Systematic anomalies in the National Ignition Facility implosion dataset have been identified in which kinetic physics may play a role, including inferred missing energy in the hohlraum, drive asymmetry in near-vacuum hohlraums, low areal density and high burn-averaged ion temperatures (T i ) compared with mainline simulations, and low ratios of the DD-neutron and DT-neutron yields and inferred T i . Several components of ICF implosions are likely to be influenced or dominated by kinetic physics: laser-plasma interactions in the LEH and hohlraum interior;more » the hohlraum wall blowoff, blowoff/gas and blowoff/ablator interfaces; the ablator and ablator/ice interface; and the DT fuel all present conditions in which kinetic physics can significantly affect the dynamics. This review presents the assembled experimental data and simulation results to date, which indicate that the effects of long mean-free-path plasma phenomena and self-generated electromagnetic fields may have a significant impact in ICF targets. Finally, simulation and experimental efforts are proposed to definitively quantify the importance of these effects at ignition-relevant conditions, including priorities for ongoing study.« less

Kinetic physics in ICF: present understanding and future directions

DOE PAGES

Rinderknecht, Hans G.; Amendt, P. A.; Wilks, S. C.; ...

2018-03-19

Kinetic physics has the potential to impact the performance of indirect-drive inertial confinement fusion (ICF) experiments. Systematic anomalies in the National Ignition Facility implosion dataset have been identified in which kinetic physics may play a role, including inferred missing energy in the hohlraum, drive asymmetry in near-vacuum hohlraums, low areal density and high burn-averaged ion temperatures (T i ) compared with mainline simulations, and low ratios of the DD-neutron and DT-neutron yields and inferred T i . Several components of ICF implosions are likely to be influenced or dominated by kinetic physics: laser-plasma interactions in the LEH and hohlraum interior;more » the hohlraum wall blowoff, blowoff/gas and blowoff/ablator interfaces; the ablator and ablator/ice interface; and the DT fuel all present conditions in which kinetic physics can significantly affect the dynamics. This review presents the assembled experimental data and simulation results to date, which indicate that the effects of long mean-free-path plasma phenomena and self-generated electromagnetic fields may have a significant impact in ICF targets. Finally, simulation and experimental efforts are proposed to definitively quantify the importance of these effects at ignition-relevant conditions, including priorities for ongoing study.« less

Kinetic physics in ICF: present understanding and future directions

NASA Astrophysics Data System (ADS)

Rinderknecht, Hans G.; Amendt, P. A.; Wilks, S. C.; Collins, G.

2018-06-01

Kinetic physics has the potential to impact the performance of indirect-drive inertial confinement fusion (ICF) experiments. Systematic anomalies in the National Ignition Facility implosion dataset have been identified in which kinetic physics may play a role, including inferred missing energy in the hohlraum, drive asymmetry in near-vacuum hohlraums, low areal density and high burn-averaged ion temperatures (〈Ti 〉) compared with mainline simulations, and low ratios of the DD-neutron and DT-neutron yields and inferred 〈Ti 〉. Several components of ICF implosions are likely to be influenced or dominated by kinetic physics: laser-plasma interactions in the LEH and hohlraum interior; the hohlraum wall blowoff, blowoff/gas and blowoff/ablator interfaces; the ablator and ablator/ice interface; and the DT fuel all present conditions in which kinetic physics can significantly affect the dynamics. This review presents the assembled experimental data and simulation results to date, which indicate that the effects of long mean-free-path plasma phenomena and self-generated electromagnetic fields may have a significant impact in ICF targets. Simulation and experimental efforts are proposed to definitively quantify the importance of these effects at ignition-relevant conditions, including priorities for ongoing study.

Plasma photonics in ICF & HED conditions

NASA Astrophysics Data System (ADS)

Michel, Pierre; Turnbull, David; Divol, Laurent; Pollock, Bradley; Chen, Cecilia Y.; Tubman, Eleanor; Goyon, Clement S.; Moody, John D.

2015-11-01

Interactions between multiple high-energy laser beams and plasma can be used to imprint refractive micro-structures in plasmas via the lasers' ponderomotive force. For example, Inertial confinement fusion (ICF) experiments at the National Ignition Facility already rely on the use of plasma gratings to redirect laser light inside an ICF target and tune the symmetry of the imploded core. More recently, we proposed new concepts of plasma polarizer and waveplate, based on two-wave mixing schemes and laser-induced plasma birefringence. In this talk, we will present new experimental results showing the first demonstration of a fully tunable plasma waveplate, which achieved near-perfect circular laser polarization. We will discuss further prospects for novel ``plasma photonics'' concepts based on two- and four-wave mixing, such as optical switches, bandpass filters, anti-reflection blockers etc. These might find applications in ICF and HED experiments by allowing to manipulate the lasers directly in-situ (i.e. inside the targets), as well as for the design of high power laser systems. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Ion kinetic dynamics in strongly-shocked plasmas relevant to ICF

DOE PAGES

Rinderknecht, H. G.; Amendt, P. A.; Rosenberg, M. J.; ...

2017-04-20

Implosions of thin-shell capsules produce strongly-shocked (M > 10), low-density (ρ ~1 mg/cc -1), high-temperature (T i ~keV) plasmas, comparable to those produced in the strongly-shocked DT-vapor in inertial confinement fusion (ICF) experiments. A series of thin-glass targets filled with mixtures of deuterium and Helium-3 gas ranging from 7% to 100% deuterium was imploded to investigate the impact of multi-species ion kinetic mechanisms in ICF-relevant plasmas over a wide range of Knudsen numbers (N K ≡ λ ii/R). Anomalous trends in nuclear yields and burn-averaged ion temperatures in implosions with N K > 0.5, which have been interpreted as signaturesmore » of ion species separation and ion thermal decoupling, are found not to be consistent with single-species ion kinetic effects alone. Experimentally inferred Knudsen numbers predict an opposite yield trend to those observed, confirming the dominance of multi-species physics in these experiments. In contrast, implosions with N K ~ 0.01 follow the expected yield trend, suggesting single-species kinetic effects are dominant. In conclusion, the impact of the observed kinetic physics mechanisms on the formation of the hotspot in ICF experiments is discussed.« less

Polymer coating of glass microballoons levitated in a focused acoustic field

NASA Technical Reports Server (NTRS)

Young, A. T.; Lee, M. C.; Feng, I.-A.; Elleman, D. D.; Wang, T. G.

1982-01-01

Inertial confinement fusion (ICF) glass microballoons (GMBs) levitated in a focusing radiator acoustic device can be coated with liquid materials by deploying the liquid into the levitation field with a stepped-horn atomizer. The GMB can be forced to the center of the coating liquid with a strong acoustically generated centering force. Water solutions of organic polymers, UV-curable liquid organic monomers, and paraffin waxes have been used to prepare solid coatings on the surface of GMBs using this technique.

Planar hydrodynamic instability computations and experiments with rugby-shaped hohlraums at the Omega laser

NASA Astrophysics Data System (ADS)

Vandenboomgaerde, M.; Liberatore, S.; Galmiche, D.; Casner, A.; Huser, G.; Jadaud, J. P.; Villette, B.

2008-05-01

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 [1, 2], 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 [3, 4]. We present experimental results and comparisons with numerical simulations.

First Measurements of Deuterium-Tritium and Deuterium-Deuterium Fusion Reaction Yields in Ignition-Scalable Direct-Drive Implosions.

PubMed

Forrest, C J; Radha, P B; Knauer, J P; Glebov, V Yu; Goncharov, V N; Regan, S P; Rosenberg, M J; Sangster, T C; Shmayda, W T; Stoeckl, C; Gatu Johnson, M

2017-03-03

The deuterium-tritium (D-T) and deuterium-deuterium neutron yield ratio in cryogenic inertial confinement fusion (ICF) experiments is used to examine multifluid effects, traditionally not included in ICF modeling. This ratio has been measured for ignition-scalable direct-drive cryogenic DT implosions at the Omega Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)OPCOB80030-401810.1016/S0030-4018(96)00325-2] using a high-dynamic-range neutron time-of-flight spectrometer. The experimentally inferred yield ratio is consistent with both the calculated values of the nuclear reaction rates and the measured preshot target-fuel composition. These observations indicate that the physical mechanisms that have been proposed to alter the fuel composition, such as species separation of the hydrogen isotopes [D. T. Casey et al., Phys. Rev. Lett. 108, 075002 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.075002], are not significant during the period of peak neutron production in ignition-scalable cryogenic direct-drive DT implosions.

Energy loss of α-particle moving in warm dense deuterium plasma: Role of local field corrections

NASA Astrophysics Data System (ADS)

Fu, Zhen-Guo; Wang, Zhigang; Zhang, Ping

2017-11-01

We theoretically study the energy loss of α-particles traveling in the warm dense plasma (WDP) of deuterium (D) with temperatures from 10 to 100 eV and electron number densities from 1023 to 1024 cm-3. Beyond the random phase approximation (RPA) model, the extended Mermin dielectric function (MDF) model including the static and dynamic local field corrections (LFC) is employed in the calculations. Compared with the static LFC, the dynamic LFC introduced in the extended MDF model gives rise to a more significant departure from the RPA result. For the plasma conditions focused in this work, the departure induced by dynamic LFC reaches almost ˜ 30 % , which may be detected in the inertial confinement fusion (ICF) related experiment. Moreover, we find that the effect of static e-e collision may be of importance (unimportance) for the WDP of D with a temperature of tens (hundreds) of eV. Our findings may be important for ICF ignition since the uncertainty induced by the correlation effects between plasma component particles is crucial for the prediction of α-particle heating in fusion plasmas.

Effects of Long- and Intermediate-Wavelength Nonuniformities on Hot-Spot Energetics of Hydrodynamic Equivalent Targets

NASA Astrophysics Data System (ADS)

Bose, A.; Betti, R.; Woo, K. M.; Christopherson, A. R.; Shvarts, D.

2015-11-01

The impact of intermediate- and low-mode nonuniformities on the performance of inertial confinement fusion (ICF) implosions is investigated by a detailed study of hot-spot energetics. It is found that low- (1 ~ 2) and intermediate-mode (1 >= 10) asymmetries affect the hot-spot hydrodynamics in very different ways. It is observed that for low-mode asymmetries, the fusion yield decreases because of a significant reduction in hot-spot pressure while the neutron-averaged hot-spot volume remains comparable to that of unperturbed (clean) simulations. On the other hand, implosions with moderate-amplitude, intermediate-wavelength modes, which are amplified by the Rayleigh-Taylor instability (RTI), exhibit a fusion-yield degradation primarily caused by a reduction in the burn volume without significant degradation of the pressure. For very large amplitudes, the intermediate modes show a ``secondary piston effect,'' where the converging RTI spikes compress a much smaller volume, allowing for a secondary conversion of the shell's kinetic energy to internal energy at a central region. Understanding the effects of nonuniformities on the hot-spot energetics provides valuable insight in determining the causes of performance degradation in current ICF experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and DE-FC02-04ER54789 (Fusion Science Center).

Modeling ICF With RAGE, BHR, And The New Laser Package

NASA Astrophysics Data System (ADS)

Cliche, Dylan; Welser-Sherrill, Leslie; Haines, Brian; Mancini, Roberto

2017-10-01

Inertial Confinement Fusion (ICF) is one method used to obtain thermonuclear burn through the either direct or indirect ablation of a millimeter-scale capsule with several lasers. Although progress has been made in theory, experiment, and diagnostics, the community has yet to reach ignition. A way of investigating this is through the use of high performance computer simulations of the implosion. RAGE is an advanced 1D, 2D, and 3D radiation adaptive grid Eulerian code used to simulate hydrodynamics of a system. Due to the unstable nature of two unequal densities accelerating into one another, it is important to include a turbulence model. BHR is a turbulence model which uses Reynolds-averaged Navier-Stokes (RANS) equations to model the mixing that occurs between the shell and fusion fuel material. Until recently, it was still difficult to model direct drive experiments because there was no laser energy deposition model in RAGE. Recently, a new laser energy deposition model has been implemented using the same ray tracing method as the Mazinisin laser package used at the OMEGA laser facility at the Laboratory for Laser Energetics (LLE) in Rochester, New York. Using the new laser package along with BHR for mixing allows us to more accurately simulate ICF implosions and obtain spatially and temporally resolved information (e.g. position, temperature, density, and mix concentrations) to give insight into what is happening inside the implosion.

Deuteron Beam Driven Fast Ignition of a Pre-Compressed Inertial Confinement Fusion (ICF) Fuel Capsule

NASA Astrophysics Data System (ADS)

Yang, Xiaoling; Miley, George; Flippo, Kirk; Hora, Heinrich; Gaillard, Sandrine; Offermann, Dustin

2012-10-01

We proposed to utilize a new ``Deuterium Cluster'' type structure for the laser interaction foil to generate an energetic deuteron beam as the fast igniter to ignite inertial confinement fusion fuel capsule. The benefit of deuteron beam driven fast ignition is that its deposition in the target fuel will not only provide heating but also fuse with fuel as they slow down in the target. The preliminary results from recent laser-deuteron acceleration experiment at LANL were encouraging. Also, in most recent calculations, we found that a 12.73% extra energy gain from deuteron beam-target fusion could be achieved when quasi-Maxwellian deuteron beam was assumed, and when a ρrb = 4.5 g/cm2 was considered, where ρ is the fuel density, and rb is the ion beam focusing radius on the target. These results provide some insight into the contribution of the extra heat produced by deuteron beam-target fusion to the hot spot ignition process. If the physics works as anticipated, this novel type of interaction foil can efficiently generate energetic deuterons during intense laser pulses. The massive yield of deuterons should turn out to be the most efficient way of igniting the DT fuel, making the dream of near-term commercialization of FI fusion more achievable.

Seeding magnetic fields for laser-driven flux compression in high-energy-density plasmas.

PubMed

Gotchev, O V; Knauer, J P; Chang, P Y; Jang, N W; Shoup, M J; Meyerhofer, D D; Betti, R

2009-04-01

A compact, self-contained magnetic-seed-field generator (5 to 16 T) is the enabling technology for a novel laser-driven flux-compression scheme in laser-driven targets. A magnetized target is directly irradiated by a kilojoule or megajoule laser to compress the preseeded magnetic field to thousands of teslas. A fast (300 ns), 80 kA current pulse delivered by a portable pulsed-power system is discharged into a low-mass coil that surrounds the laser target. A >15 T target field has been demonstrated using a <100 J capacitor bank, a laser-triggered switch, and a low-impedance (<1 Omega) strip line. The device has been integrated into a series of magnetic-flux-compression experiments on the 60 beam, 30 kJ OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The initial application is a novel magneto-inertial fusion approach [O. V. Gotchev et al., J. Fusion Energy 27, 25 (2008)] to inertial confinement fusion (ICF), where the amplified magnetic field can inhibit thermal conduction losses from the hot spot of a compressed target. This can lead to the ignition of massive shells imploded with low velocity-a way of reaching higher gains than is possible with conventional ICF.

LLE 2008 annual report, October 2007 - September 2008

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2009-01-31

The research program at the University of Rochester’s Laboratory for Laser Energetics (LLE) focuses on inertial confinement fusion (ICF) research supporting the goal of achieving ignition on the National Ignition Facility (NIF). This program includes the full use of the OMEGA EP Laser System. Within the National Ignition Campaign (NIC), LLE is the lead laboratory for the validation of the performance of cryogenic target implosions, essential to all forms of ICF ignition. LLE has taken responsibility for a number of critical elements within the Integrated Experimental Teams (IET’s) supporting the demonstration of indirect-drive ignition on the NIF and is themore » lead laboratory for the validation of the polardrive approach to ignition on the NIF. LLE is also developing, testing, and building a number of diagnostics to be deployed on the NIF for the NIC.« less

Laser Hole Boring into Overdense Plasma and Relativistic Electron Currents for Fast Ignition of ICF Targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pukhov, A.; Meyer-ter-Vehn, J.

Laser hole boring and relativistic electron transport into plasma of 10 times critical density is studied by means of 2D particle-in-cell simulation. At intensities of I{sub 0}{lambda}{sup 2}=10{sup 20} W(cm){sup {minus}2} {mu}m{sup 2}, a channel 12{lambda} deep and 3{lambda} in diameter has formed after 200 laser cycles. The laser driven electron current carries up to 40{percent} of the incident laser power. When penetrating the overdense region, it breaks up into several filaments at early times, but is channeled into a single magnetized jet later on. These features are essential for fast ignition of targets for inertial confinement fusion (ICF). {copyright}more » {ital 1997} {ital The American Physical Society}« less

Investigation of complete and incomplete fusion in the 7Li+124Sn reaction near Coulomb barrier energies

NASA Astrophysics Data System (ADS)

Parkar, V. V.; Sharma, Sushil K.; Palit, R.; Upadhyaya, S.; Shrivastava, A.; Pandit, S. K.; Mahata, K.; Jha, V.; Santra, S.; Ramachandran, K.; Nag, T. N.; Rath, P. K.; Kanagalekar, Bhushan; Trivedi, T.

2018-01-01

The complete and incomplete fusion cross sections for the 7Li+124Sn reaction were measured using online and offline characteristic γ -ray detection techniques. The complete fusion (CF) cross sections at energies above the Coulomb barrier were found to be suppressed by ˜26 % compared to the coupled channel calculations. This suppression observed in complete fusion cross sections is found to be commensurate with the measured total incomplete fusion (ICF) cross sections. There is a distinct feature observed in the ICF cross sections, i.e., t capture is found to be dominant compared to α capture at all the measured energies. A simultaneous explanation of complete, incomplete, and total fusion (TF) data was also obtained from the calculations based on the continuum discretized coupled channel method with short range imaginary potentials. The cross section ratios of CF/TF and ICF/TF obtained from the data as well as the calculations showed the dominance of ICF at below-barrier energies and CF at above-barrier energies.

A measurable Lawson criterion and hydro-equivalent curves for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, C. D.; Betti, R.; Departments of Mechanical Engineering and Physics and Astronomy, University of Rochester, Rochester, New York 14623

2008-10-15

It is shown that the ignition condition (Lawson criterion) for inertial confinement fusion (ICF) can be cast in a form dependent on the only two parameters of the compressed fuel assembly that can be measured with existing techniques: the hot spot ion temperature (T{sub i}{sup h}) and the total areal density ({rho}R{sub tot}), which includes the cold shell contribution. A marginal ignition curve is derived in the {rho}R{sub tot}, T{sub i}{sup h} plane and current implosion experiments are compared with the ignition curve. On this plane, hydrodynamic equivalent curves show how a given implosion would perform with respect to themore » ignition condition when scaled up in the laser-driver energy. For 3<{sub n}<6 keV, an approximate form of the ignition condition (typical of laser-driven ICF) is {sub n}{sup 2.6}{center_dot}<{rho}R{sub tot}>{sub n}>50 keV{sup 2.6}{center_dot} g/cm{sup 2}, where <{rho}R{sub tot}>{sub n} and {sub n} are the burn-averaged total areal density and hot spot ion temperature, respectively. Both quantities are calculated without accounting for the alpha-particle energy deposition. Such a criterion can be used to determine how surrogate D{sub 2} and subignited DT target implosions perform with respect to the one-dimensional ignition threshold.« less

Three-dimensional modeling of the neutron spectrum to infer plasma conditions in cryogenic inertial confinement fusion implosions

NASA Astrophysics Data System (ADS)

Weilacher, F.; Radha, P. B.; Forrest, C.

2018-04-01

Neutron-based diagnostics are typically used to infer compressed core conditions such as areal density and ion temperature in deuterium-tritium (D-T) inertial confinement fusion (ICF) implosions. Asymmetries in the observed neutron-related quantities are important to understanding failure modes in these implosions. Neutrons from fusion reactions and their subsequent interactions including elastic scattering and neutron-induced deuteron breakup reactions are tracked to create spectra. It is shown that background subtraction is important for inferring areal density from backscattered neutrons and is less important for the forward-scattered neutrons. A three-dimensional hydrodynamic simulation of a cryogenic implosion on the OMEGA Laser System [Boehly et al., Opt. Commun. 133, 495 (1997)] using the hydrodynamic code HYDRA [Marinak et al., Phys. Plasmas 8, 2275 (2001)] is post-processed using the tracking code IRIS3D. It is shown that different parts of the neutron spectrum from the view can be mapped into different regions of the implosion, enabling an inference of an areal-density map. It is also shown that the average areal-density and an areal-density map of the compressed target can be reconstructed with a finite number of detectors placed around the target chamber. Ion temperatures are inferred from the width of the D-D and D-T fusion neutron spectra. Backgrounds can significantly alter the inferred ion temperatures from the D-D reaction, whereas they insignificantly influence the inferred D-T ion temperatures for the areal densities typical of OMEGA implosions. Asymmetries resulting in fluid flow in the core are shown to influence the absolute inferred ion temperatures from both reactions, although relative inferred values continue to reflect the underlying asymmetry pattern. The work presented here is part of the wide range of the first set of studies performed with IRIS3D. This code will continue to be used for post-processing detailed hydrodynamic simulations and interpreting observed neutron spectra in ICF implosions.

Development of Eulerian Code Modeling for ICF Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, Paul A.

2014-02-27

One of the most pressing unexplained phenomena standing in the way of ICF ignition is understanding mix and how it interacts with burn. Experiments were being designed and fielded as part of the Defect-Induced Mix Experiment (DIME) project to obtain data about the extent of material mix and how this mix influenced burn. Experiments on the Omega laser and National Ignition Facility (NIF) provided detailed data for comparison to the Eulerian code RAGE1. The Omega experiments were able to resolve the mix and provide “proof of principle” support for subsequent NIF experiments, which were fielded from July 2012 through Junemore » 2013. The Omega shots were fired at least once per year between 2009 and 2012. RAGE was not originally designed to model inertial confinement fusion (ICF) implosions. It still lacks lasers, so the code has been validated using an energy source. To test RAGE, the simulation output is compared to data and by means of postprocessing tools that were developed. Here, the various postprocessing tools are described with illustrative examples.« less

Isochoric Implosions for Fast Ignition

NASA Astrophysics Data System (ADS)

Clark, Daniel; Tabak, Max

2006-10-01

Various gain models have shown the potentially great advantages of Fast Ignition (FI) Inertial Confinement Fusion (ICF) over its conventional hotspot ignition counterpart. These gain models, however, all assume nearly uniform-density fuel assemblies. By contrast, typical ICF implosions yield hollowed fuel assemblies with a high-density shell of fuel surrounding a low-density, high-pressure hotspot. To realize fully the advantages of FI, then, an alternative implosion design must be found which yields nearly isochoric fuel assemblies without substantial hotspots. 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, i.e., accessible peak pressures, shell aspect ratios, etc. An implosion scheme is presented which meets all of these requirements, suggesting the possibility of genuinely isochoric implosions for FI.

Full-wave and ray-based modeling of cross-beam energy transfer between laser beams with distributed phase plates and polarization smoothing

DOE PAGES

Follett, R. K.; Edgell, D. H.; Froula, D. H.; ...

2017-10-20

Radiation-hydrodynamic simulations of inertial confinement fusion (ICF) experiments rely on ray-based cross-beam energy transfer (CBET) models to calculate laser energy deposition. The ray-based models assume locally plane-wave laser beams and polarization averaged incoherence between laser speckles for beams with polarization smoothing. The impact of beam speckle and polarization smoothing on crossbeam energy transfer (CBET) are studied using the 3-D wave-based laser-plasma-interaction code LPSE. The results indicate that ray-based models under predict CBET when the assumption of spatially averaged longitudinal incoherence across the CBET interaction region is violated. A model for CBET between linearly-polarized speckled beams is presented that uses raymore » tracing to solve for the real speckle pattern of the unperturbed laser beams within the eikonal approximation and gives excellent agreement with the wavebased calculations. Lastly, OMEGA-scale 2-D LPSE calculations using ICF relevant plasma conditions suggest that the impact of beam speckle on laser absorption calculations in ICF implosions is small (< 1%).« less

Full-wave and ray-based modeling of cross-beam energy transfer between laser beams with distributed phase plates and polarization smoothing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Follett, R. K.; Edgell, D. H.; Froula, D. H.

Radiation-hydrodynamic simulations of inertial confinement fusion (ICF) experiments rely on ray-based cross-beam energy transfer (CBET) models to calculate laser energy deposition. The ray-based models assume locally plane-wave laser beams and polarization averaged incoherence between laser speckles for beams with polarization smoothing. The impact of beam speckle and polarization smoothing on crossbeam energy transfer (CBET) are studied using the 3-D wave-based laser-plasma-interaction code LPSE. The results indicate that ray-based models under predict CBET when the assumption of spatially averaged longitudinal incoherence across the CBET interaction region is violated. A model for CBET between linearly-polarized speckled beams is presented that uses raymore » tracing to solve for the real speckle pattern of the unperturbed laser beams within the eikonal approximation and gives excellent agreement with the wavebased calculations. Lastly, OMEGA-scale 2-D LPSE calculations using ICF relevant plasma conditions suggest that the impact of beam speckle on laser absorption calculations in ICF implosions is small (< 1%).« less

Effect of projectile on incomplete fusion reactions at low energies

NASA Astrophysics Data System (ADS)

Sharma, Vijay R.; Shuaib, Mohd.; Yadav, Abhishek; Singh, Pushpendra P.; Sharma, Manoj K.; Kumar, R.; Singh, Devendra P.; Singh, B. P.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.; Prasad, R.

2017-11-01

Present work deals with the experimental studies of incomplete fusion reaction dynamics at energies as low as ≈ 4 - 7 MeV/A. Excitation functions populated via complete fusion and/or incomplete fusion processes in 12C+175Lu, and 13C+169Tm systems have been measured within the framework of PACE4 code. Data of excitation function measurements on comparison with different projectile-target combinations suggest the existence of ICF even at slightly above barrier energies where complete fusion (CF) is supposed to be the sole contributor, and further demonstrates strong projectile structure dependence of ICF. The incomplete fusion strength functions for 12C+175Lu, and 13C+169Tm systems are analyzed as a function of various physical parameters at a constant vrel ≈ 0.053c. It has been found that one neutron (1n) excess projectile 13C (as compared to 12C) results in less incomplete fusion contribution due to its relatively large negative α-Q-value, hence, α Q-value seems to be a reliable parameter to understand the ICF dynamics at low energies. In order to explore the reaction modes on the basis of their entry state spin population, the spin distribution of residues populated via CF and/or ICF in 16O+159Tb system has been done using particle-γ coincidence technique. CF-α and ICF-α channels have been identified from backward (B) and forward (F) α-gated γspectra, respectively. Reaction dependent decay patterns have been observed in different α emitting channels. The CF channels are found to be fed over a broad spin range, however, ICF-α channels was observed only for high-spin states. Further, the existence of incomplete fusion at low bombarding energies indicates the possibility to populate high spin states

Exploring incomplete fusion fraction in 6,7Li induced nuclear reactions

NASA Astrophysics Data System (ADS)

Parkar, V. V.; Jha, V.; Kailas, S.

2017-11-01

We have included breakup effects explicitly to simultaneously calculate the measured cross-sections of the complete fusion, incomplete fusion, and total fusion for 6,7Li projectiles on various targets using the Continuum Discretized Coupled Channels method. The breakup absorption cross-sections obtained with different choices of short range imaginary potentials are utilized to evaluate the individual α-capture and d/t-capture cross-sections and compare with the measured data. It is interesting to note, while in case of 7Li projectile the cross-sections for triton-ICF/triton-capture is far more dominant than α-ICF/α-capture at all energies, similar behavior is not observed in case of 6Li projectile for the deuteron-ICF/deuteron-capture and α-ICF/α-capture. Both these observations are also corroborated by the experimental data for all the systems studied.

Effects of the Ponderomotive Terms in the Thermal Transport on the Hydrodynamic Flow in Inertial Confinement Fusion Experiments

NASA Astrophysics Data System (ADS)

Goncharov, V. N.; Li, G.

2004-11-01

Electron thermal transport is significantly modified by the laser-induced electric fields near the turning point and at the critical surface. It is shown that such modifications lead to an additional limitation in the heat flux in laser-produced plasmas. Furthermore, the ponderomotive terms in the heat flux lead to a steepening in the electron-density profile, which is shown to be a larger effect than the profile modification due to the ponderomotive force [W.L. Kruer, The Physics of Laser--Plasma Interactions, Frontiers in Physics, Vol. 73, edited by D. Pines (Addison-Wesley, Redwood City, CA, 1988)]. To take into account the nonlocal effects, the delocalization model developed in Ref. 2 [G.P. Schurtz, Ph.D. Nicolaï, and M. Busquet, Phys. Plasmas 7, 4238 (2000).] has been applied to conditions relevant to ICF experiments. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

High temperature surface effects of He + implantation in ICF fusion first wall materials

NASA Astrophysics Data System (ADS)

Zenobia, Samuel J.; Radel, R. F.; Cipiti, B. B.; Kulcinski, Gerald L.

2009-06-01

The first wall armor of the inertial confinement fusion reactor chambers must withstand high temperatures and significant radiation damage from target debris and neutrons. The resilience of multiple materials to one component of the target debris has been investigated using energetic (20-40 keV) helium ions generated in the inertial electrostatic confinement device at the University of Wisconsin. The materials studied include: single-crystalline, and polycrystalline tungsten, tungsten-coated tantalum-carbide 'foams', tungsten-rhenium alloy, silicon carbide, carbon-carbon velvet, and tungsten-coated carbon-carbon velvet. Steady-state irradiation temperatures ranged from 750 to 1250 °C with helium fluences between 5 × 10 17 and 1 × 10 20 He +/cm 2. The crystalline, rhenium alloyed, carbide foam, and powder metallurgical tungsten specimens each experienced extensive pore formation after He + irradiation. Flaking and pore formation occurred on silicon carbide samples. Individual fibers of carbon-carbon velvet specimens sustained erosion and corrugation, in addition to the roughening and rupturing of tungsten coatings after helium ion implantation.

Experimental investigation of the deformable mirror with bidirectional thermal actuators.

PubMed

Huang, Lei; Ma, Xingkun; Gong, Mali; Bian, Qi

2015-06-29

A deformable mirror with actuators of thermoelectric coolers (TECs) is introduced in this paper. Due to the bidirectional thermal actuation property of the TEC, both upward and downward surface control is available for the DM. The response functions of the actuators are investigated. A close-loop wavefront control experiment is performed too, where the defocus and the astigmatism were corrected. The results reveal that there is a promising prospect for the novel design to be used in corrections of static aberrations, such as in the Inertial Confinement Fusion (ICF).

Measuring the properties of shock released Quartz and Parylene-N

NASA Astrophysics Data System (ADS)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2016-10-01

The high pressure and temperature properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies the single shock Hugoniot. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography.

The ePLAS Code for Ignition Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mason, Rodney J

2012-09-20

Inertial Confinement Fusion (ICF) presents unique opportunities for the extraction of clean energy from Fusion. Intense lasers and particle beams can create and interact with such plasmas, potentially yielding sufficient energy to satisfy all our national needs. However, few models are available to help aid the scientific community in the study and optimization of such interactions. This project enhanced and disseminated the computer code ePLAS for the early understanding and control of Ignition in ICF. ePLAS is a unique simulation code that tracks the transport of laser light to a target, the absorption of that light resulting in the generationmore » and transport of hot electrons, and the heating and flow dynamics of the background plasma. It uses an implicit electromagnetic field-solving method to greatly reduce computing demands, so that useful target interaction studies can often be completed in 15 minutes on a portable 2.1 GHz PC. The code permits the rapid scoping of calculations for the optimization of laser target interactions aimed at fusion. Recent efforts have initiated the use of analytic equations of state (EOS), K-alpha image rendering graphics, allocatable memory for source-free usage, and adaption to the latest Mac and Linux Operating Systems. The speed and utility of ePLAS are unequaled in the ICF simulation community. This project evaluated the effects of its new EOSs on target heating, compared fluid and particle models for the ions, initiated the simultaneous use of both ion models in the code, and studied long time scale 500 ps hot electron deposition for shock ignition. ePLAS has been granted EAR99 export control status, permitting export without a license to most foreign countries. Beta-test versions of ePLAS have been granted to several Universities and Commercial users. The net Project was aimed at achieving early success in the laboratory ignition of thermonuclear targets and the mastery of controlled fusion power for the nation.« less

Influence of radiative processes on the ignition of deuterium–tritium plasma containing inactive impurities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gus’kov, S. Yu., E-mail: guskov@sci.lebedev.ru; Sherman, V. E.

2016-08-15

The degree of influence of radiative processes on the ignition of deuterium–tritium (DT) plasma has been theoretically studied as dependent on the content of inactive impurities in plasma. The analytic criterion of plasma ignition in inertial confinement fusion (ICF) targets is modified taking into account the absorption of intrinsic radiation from plasma in the ignition region. The influence of radiative processes on the DT plasma ignition has been analytically and numerically studied for plasma that contains a significant fraction of inactive impurities either as a result of DT fuel mixing with ICF target ablator material or as a result ofmore » using light metal DT-hydrides as solid noncryogenic fuel. It has been shown that the effect of the absorption of intrinsic radiation leads to lower impurity-induced increase in the ignition energy as compared to that calculated in the approximation of optically transparent ignition region.« less

Coated foams, preparation, uses and articles

DOEpatents

Duchane, D.V.; Barthell, B.L.

1982-10-21

Hydrophobic cellular material is coated with a thin hydrophilic polymer skin which stretches tightly over the foam but which does not fill the cells of the foam, thus resulting in a polymer-coated foam structure having a smoothness which was not possible in the prior art. In particular, when the hydrophobic cellular material is a specially chosen hydrophobic polymer foam and is formed into arbitrarily chosen shapes prior to the coating with hydrophilic polymer, inertial confinement fusion (ICF) targets of arbitrary shapes can be produced by subsequently coating the shapes with metal or with any other suitable material. New articles of manufacture are produced, including improved ICF targets, improved integrated circuits, and improved solar reflectors and solar collectors. In the coating method, the cell size of the hydrophobic cellular material, the viscosity of the polymer solution used to coat, and the surface tension of the polymer solution used to coat are all very important to the coating.

Measurements of Deuterium-Tritium Fuel Fractionation from Kinetic Effects in Ignition-Relevant Direct-Drive Cryogenic Implosions

NASA Astrophysics Data System (ADS)

Forrest, C.; Glebov, V. Yu.; Knauer, J. P.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Stoeckl, C.

2016-10-01

Measurements of DT and DD reaction yields have been studied using ignition-relevant, cryogenically cooled deuterium-tritium gas-filled cryogenic DT targets in inertial confinement fusion (ICF) implosions. In these experiments, carried out at the Omega Laser Facility, highresolution time-of-flight spectroscopy was used to measure the primary neutron peak distribution required to infer the DT and DD reaction yields. From these measurements, it will be shown that the yield ratio has a χ2/per degree of freedom of 0.67 as compared with the measured fraction of the target fuel composition. This observation indicates that kinetic effects leading to species separation are insignificant in ICF ignition-relevant DT implosions on OMEGA. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Summaries of FY16 LANL experimental campaigns at the OMEGA and EP Laser Facilities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loomis, Eric Nicholas; Merritt, Elizabeth Catherine; Montgomery, David

In FY16, Los Alamos National Laboratory carried out 22 shot days on the OMEGA and OMEGA- EP laser facilities in the areas of High Energy Density (HED) Science and Inertial Confinement Fusion (ICF). In HED our focus areas were on radiation flow, hydrodynamic turbulent mix and burn, warm dense matter equations of state, and coupled Kelvin-­Helmholtz (KH)/Richtmyer-­ Meshkov (RM) instability growth. For ICF our campaigns focused on the Priority Research Directions (PRD) of implosion phase mix and stagnation and burn, specifically as they pertain to Laser Direct Drive (LDD). We also had several focused shot days on transport properties inmore » the kinetic regime. We continue to develop advanced diagnostics such as Neutron Imaging, Gamma Reaction History, and Gas Cherenkov Detectors. Below are a summary of our campaigns, their motivation, and main results from this year.« less

Topology of megagauss magnetic fields and of heat-carrying electrons produced in a high-power laser-solid interaction.

PubMed

Lancia, L; Albertazzi, B; Boniface, C; Grisollet, A; Riquier, R; Chaland, F; Le Thanh, K-C; Mellor, Ph; Antici, P; Buffechoux, S; Chen, S N; Doria, D; Nakatsutsumi, M; Peth, C; Swantusch, M; Stardubtsev, M; Palumbo, L; Borghesi, M; Willi, O; Pépin, H; Fuchs, J

2014-12-05

The intricate spatial and energy distribution of magnetic fields, self-generated during high power laser irradiation (at Iλ^{2}∼10^{13}-10^{14}  W.cm^{-2}.μm^{2}) of a solid target, and of the heat-carrying electron currents, is studied in inertial confinement fusion (ICF) relevant conditions. This is done by comparing proton radiography measurements of the fields to an improved magnetohydrodynamic description that fully takes into account the nonlocality of the heat transport. We show that, in these conditions, magnetic fields are rapidly advected radially along the target surface and compressed over long time scales into the dense parts of the target. As a consequence, the electrons are weakly magnetized in most parts of the plasma flow, and we observe a reemergence of nonlocality which is a crucial effect for a correct description of the energetics of ICF experiments.

eHXI: A permanently installed, hard x-ray imager for the National Ignition Facility

DOE PAGES

Doppner, T.; Bachmann, B.; Albert, F.; ...

2016-06-14

We have designed and built a multi-pinhole imaging system for high energy x-rays (≥ 50 keV) that is permanently installed in the equatorial plane outside of the target chamber at the National Ignition Facility (NIF). It records absolutely-calibrated, time-integrated x-ray images with the same line-of-sight as the multi-channel, spatially integrating hard x-ray detector FFLEX [McDonald et al., Rev. Sci. Instrum. 75 (2004) 3753], having a side view of indirect-drive inertial confinement fusion (ICF) implosion targets. The equatorial hard x-ray imager (eHXI) has recorded images on the majority of ICF implosion experiments since May 2011. Lastly, eHXI provides valuable information onmore » hot electron distribution in hohlraum experiments, target alignment, potential hohlraum drive asymmetries and serves as a long term reference for the FFLEX diagnostics.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenberg, M. J., E-mail: mrosenbe@mit.edu; Zylstra, A. B.; Séguin, F. H.

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 themore » 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.« less

BigFoot: a program to reduce risk for indirect drive laser fusion

NASA Astrophysics Data System (ADS)

Thomas, Cliff

2017-10-01

The conventional approach to inertial confinement fusion (ICF) with indirect drive is to design for high convergence (40), DT areal density, and target gain. By construction, this strategy is challenged by low-mode control of the implosion (Legendre P2 and P4), instability, and difficulties interpreting data. Here we consider an alternative - an approach to ICF that emphasizes control. To begin, we optimize for hohlraum predictability, and coupling to the capsule. Rather than focus on density, we work on making a high-energy hotspot we can diagnose and ``tune'' at low convergence (20). Though gain is reduced, this makes it possible to study (and improve) stagnation physics in a regime relevant to ignition (1E16-1E17). Further improvements can then be made with small, incremental increases in areal density, target scale, etc. Details regarding the ``BigFoot'' platform and pulse are reported, including recent findings. Work that could enable additional improvements in capsule stability and hohlraum control 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.

Numerical studies of the use of thin high-Z layers for reducing laser imprint in direct-drive inertial-fusion targets

NASA Astrophysics Data System (ADS)

Bates, Jason; Schmitt, Andrew; Karasik, Max; Obenschain, Steve

2012-10-01

Using the FAST code, we present numerical studies of the effect of thin metallic layers with high atomic number (high-Z) on the hydrodynamics of directly-driven inertial-confinement-fusion (ICF) targets. Previous experimental work on the NIKE Laser Facility at the U.S. Naval Research Laboratory demonstrated that the use of high-Z layers may be efficacious in reducing laser non-uniformities imprinted on the target during the start-up phase of the implosion. Such a reduction is highly desirable in a direct-drive ICF scenario because laser non-uniformities seed hydrodynamic instabilities that can amplify during the implosion process, prevent uniform compression and spoil high gain. One of the main objectives of the present work is to assess the utility of high-Z layers for achieving greater laser uniformity in polar-drive target designs planned for the National Ignition Facility. To address this problem, new numerical routines have recently been incorporated in the FAST code, including an improved radiation-transfer package and a three-dimensional ray-tracing algorithm. We will discuss these topics, and present initial simulation results for high-Z planar-target experiments planned on the NIKE Laser Facility later this year.

Uncertainty Quantification For Physical and Numerical Diffusion Models In Inertial Confinement Fusion Simulations

NASA Astrophysics Data System (ADS)

Rana, Verinder S.

This thesis concerns simulations of Inertial Confinement Fusion. Inertial confinement is carried out in a large scale facility at National Ignition Facility. The experiments have failed to reproduce design calculations, and so uncertainty quantification of calculations is an important asset. Uncertainties can be classified as aleatoric or epistemic. This thesis is concerned with aleatoric uncertainty quantification. Among the many uncertain aspects that affect the simulations, we have narrowed our study of possible uncertainties. The first source of uncertainty we present is the amount of pre-heating of the fuel done by hot electrons. The second source of uncertainty we consider is the effect of the algorithmic and physical transport diffusion and their effect on the hot spot thermodynamics. Physical transport mechanisms play an important role for the entire duration of the ICF capsule, so modeling them correctly becomes extremely vital. In addition, codes that simulate material mixing introduce numerical (algorithmically) generated transport across the material interfaces. This adds another layer of uncertainty in the solution through the artificially added diffusion. The third source of uncertainty we consider is physical model uncertainty. The fourth source of uncertainty we focus on a single localized surface perturbation (a divot) which creates a perturbation to the solution that can potentially enter the hot spot to diminish the thermonuclear environment. Jets of ablator material are hypothesized to enter the hot spot and cool the core, contributing to the observed lower reactions than predicted levels. A plasma transport package, Transport for Inertial Confinement Fusion (TICF) has been implemented into the Radiation Hydrodynamics code FLASH, from the University of Chicago. TICF has thermal, viscous and mass diffusion models that span the entire ICF implosion regime. We introduced a Quantum Molecular Dynamics calibrated thermal conduction model due to Hu for thermal transport. The numerical approximation uncertainties are introduced by the choice of a hydrodynamic solver for a particular flow. Solvers tend to be diffusive at material interfaces and the Front Tracking (FT) algorithm, which is an already available software code in the form of an API, helps to ameliorate such effects. The FT algorithm has also been implemented in FLASH and we use this to study the effect that divots can have on the hot spot properties.

Conceptual design of a laser fusion power plant. Part I. An integrated facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This study is a new preliminary conceptual design and economic analysis of an inertial confinement fusion (ICF) power plant performed by Bechtel under the direction of Lawrence Livermore National Laboratory (LLNL). The purpose of a new conceptual design is to examine alternatives to the LLNL HYLIFE power plant and to incorporate information from the recent liquid metal cooled power plant conceptual design study (CDS) into the reactor system and balance of plant design. A key issue in the design of a laser fusion power plant is the degree of symmetry in the illumination of the target that will be requiredmore » for a proper burn. Because this matter is expected to remain unresolved for some time, another purpose of this study is to determine the effect of symmetry requirements on the total plant size, layout, and cost.« less

Suprathermal Ion Populations in ICF Plasmas - Implications for Diagnostics and Ignition

NASA Astrophysics Data System (ADS)

Knapp, Patrick; Schmit, Paul; Sinars, Daniel

2013-10-01

We report on investigations into the effects of suprathermal ion populations on neutron production in Inertial Confinement and Magneto-Inertial Fusion plasmas. In a recent article we showed that a suprathermal population taking the form of a power-law in energy will significantly modify the shape and width of the neutron spectrum and can dramatically increase the fusion reactivity compared to the Maxwellian case. Specific diagnostic signatures are discussed in detail. We build on this work to include the effect of an applied magnetic field on the neutron spectra, isotropy and production rate. Finally, the impact that these modifications have on the ability to reach high fusion yields and ignition is discussed. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration.

Project Icarus: Nuclear Fusion Propulsion Concept Comparison

NASA Astrophysics Data System (ADS)

Stanic, M.

Project Icarus will use nuclear fusion as the primary propulsion, since achieving breakeven is imminent within the next decade. Therefore, fusion technology provides confidence in further development and fairly high technological maturity by the time the Icarus mission would be plausible. Currently there are numerous (over 2 dozen) different fusion approaches that are simultaneously being developed around the World and it is difficult to predict which of the concepts is going to be the most successful one. This study tried to estimate current technological maturity and possible technological extrapolation of fusion approaches for which appropriate data could be found. Figures of merit that were assessed include: current technological state, mass and volume estimates, possible gain values, main advantages and disadvantages of the concept and an attempt to extrapolate current technological state for the next decade or two. Analysis suggests that Magnetic Confinement Fusion (MCF) concepts are not likely to deliver sufficient performance due to size, mass, gain and large technological barriers of the concept. However, ICF and PJMIF did show potential for delivering necessary performance, assuming appropriate techno- logical advances. This paper is a submission of the Project Icarus Study Group.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haines, Brian M., E-mail: bmhaines@lanl.gov

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 duemore » 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.« less

A hybrid-drive nonisobaric-ignition scheme for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, X. T., E-mail: xthe@iapcm.ac.cn; Center for Applied Physics and Technology, HEDPS, Peking University, Beijing 100871; IFSA Collaborative Innovation Center of MoE, Shanghai Jiao-Tong University, Shanghai 200240

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 radiationmore » 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.« less

Hard X-ray Imaging for Measuring Laser Absorption Spatial Profiles on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dewald, E L; Jones, O S; Landen, O L

2006-04-25

Hard x-ray (''Thin wall'') imaging will be employed on the National Ignition Facility (NIF) to spatially locate laser beam energy deposition regions on the hohlraum walls in indirect drive Inertial Confinement Fusion (ICF) experiments, relevant for ICF symmetry tuning. Based on time resolved imaging of the hard x-ray emission of the laser spots, this method will be used to infer hohlraum wall motion due to x-ray and laser ablation and any beam refraction caused by plasma density gradients. In optimizing this measurement, issues that have to be addressed are hard x-ray visibility during the entire ignition laser pulse with intensitiesmore » ranging from 10{sup 13} to 10{sup 15} W/cm{sup 2}, as well as simultaneous visibility of the inner and the outer laser drive cones. In this work we will compare the hard x-ray emission calculated by LASNEX and analytical modeling with thin wall imaging data recorded previously on Omega and during the first hohlraum experiments on NIF. Based on these calculations and comparisons the thin wall imaging will be optimized for ICF/NIF experiments.« less

Development of hierarchical, tunable pore size polymer foams for ICF targets

DOE PAGES

Hamilton, Christopher E.; Lee, Matthew Nicholson; Parra-Vasquez, A. Nicholas Gerardo

2016-08-01

In this study, one of the great challenges of inertial confinement fusion experiments is poor understanding of the effects of reactant heterogeneity on fusion reactions. The Marble campaign, conceived at Los Alamos National Laboratory, aims to gather new insights into this issue by utilizing target capsules containing polymer foams of variable pore sizes, tunable over an order of magnitude. Here, we describe recent and ongoing progress in the development of CH and CH/CD polymer foams in support of Marble. Hierarchical and tunable pore sizes have been achieved by utilizing a sacrificial porogen template within an open-celled poly(divinylbenzene) or poly(divinylbenzene-co-styrene) aerogelmore » matrix, resulting in low-density foams (~30 mg/ml) with continuous multimodal pore networks.« less

Minimizing scatter-losses during pre-heat for magneto-inertial fusion targets

NASA Astrophysics Data System (ADS)

Geissel, Matthias; Harvey-Thompson, Adam J.; Awe, Thomas J.; Bliss, David E.; Glinsky, Michael E.; Gomez, Matthew R.; Harding, Eric; Hansen, Stephanie B.; Jennings, Christopher; Kimmel, Mark W.; Knapp, Patrick; Lewis, Sean M.; Peterson, Kyle; Schollmeier, Marius; Schwarz, Jens; Shores, Jonathon E.; Slutz, Stephen A.; Sinars, Daniel B.; Smith, Ian C.; Speas, C. Shane; Vesey, Roger A.; Weis, Matthew R.; Porter, John L.

2018-02-01

The size, temporal and spatial shape, and energy content of a laser pulse for the pre-heat phase of magneto-inertial fusion affect the ability to penetrate the window of the laser-entrance-hole and to heat the fuel behind it. High laser intensities and dense targets are subject to laser-plasma-instabilities (LPI), which can lead to an effective loss of pre-heat energy or to pronounced heating of areas that should stay unexposed. While this problem has been the subject of many studies over the last decades, the investigated parameters were typically geared towards traditional laser driven Inertial Confinement Fusion (ICF) with densities either at 10% and above or at 1% and below the laser's critical density, electron temperatures of 3-5 keV, and laser powers near (or in excess of) 1 × 1015 W/cm2. In contrast, Magnetized Liner Inertial Fusion (MagLIF) [Slutz et al., Phys. Plasmas 17, 056303 (2010) and Slutz and Vesey, Phys. Rev. Lett. 108, 025003 (2012)] currently operates at 5% of the laser's critical density using much thicker windows (1.5-3.5 μm) than the sub-micron thick windows of traditional ICF hohlraum targets. This article describes the Pecos target area at Sandia National Laboratories using the Z-Beamlet Laser Facility [Rambo et al., Appl. Opt. 44(12), 2421 (2005)] as a platform to study laser induced pre-heat for magneto-inertial fusion targets, and the related progress for Sandia's MagLIF program. Forward and backward scattered light were measured and minimized at larger spatial scales with lower densities, temperatures, and powers compared to LPI studies available in literature.

Ignition and pusher adiabat

NASA Astrophysics Data System (ADS)

Cheng, B.; Kwan, T. J. T.; Wang, Y. M.; Yi, S. A.; Batha, S. H.; Wysocki, F.

2018-07-01

In the last five years, large amounts of high quality data on inertial confinement fusion (ICF) experiments were produced at the National Ignition Facility (NIF). From this data we have significantly advanced our scientific understanding of the physics of thermonuclear (TN) ignition and identified critical issues that must be addressed to achieve a burning hotspot, such as implosion energetics, pusher adiabat, tamping effects, and confinement time. In this paper we present a review of recently developed TN ignition and implosion scaling theory (Cheng et al 2013 Phys. Rev. E 88 041101; Cheng et al 2014 Phys. Plasmas 21 10270) that characterizes the thermodynamic properties of the hotspot and the ignition criteria for ICF. We compare our theoretical predictions with NIF data and find good agreement between theory and experiments. We demonstrate the fundamental effects of the pusher adiabat on the energy partition between the cold shell and the hot deuterium–tritium (DT) gas, and thus on the integrated performance of ICF capsules. Theoretical analysis of NIF experiments (Cheng et al 2015 Phys. Plasmas 22 082704; Melvin et al 2015 Phys. Plasmas 22 022708; Cheng et al 2016 Phys. Plasmas 23 120702) and physical explanations of the discrepancies between theory, data, and simulations are presented. It is shown that the true experimental adiabat of the cold DT fuel can be inferred from neutron image data of a capsule implosion. We show that the ablator mix and preheat in the cold fuel can be estimated from the experimentally inferred hotspot mix. Finally, possible paths forward to reach higher yields at NIF implied by the theory are discussed.

In-flight neutron spectra as an ICF diagnostic for implosion asymmetries

NASA Astrophysics Data System (ADS)

Cerjan, C.; Sayre, D. B.; Sepke, S. M.

2018-02-01

The yield and spectral shape of the neutrons produced during in-flight reactions provide stringent constraints upon the symmetry of the fully compressed fuel conditions in Inertial Confinement Fusion implosions. Neutron production from a specific deuterium gas-filled implosion is simulated in detail and compared with the experimental neutron spectra along two lines-of-sight. An approximate reactivity formulation is applied to obtain further insight into the underlying fuel configuration. This analysis suggests that the differences observed in the observed spectra correspond to angularly dependent triton velocity distributions created by an asymmetric plasma configuration.

Three-dimensional modeling of the neutron spectrum to infer plasma conditions in cryogenic inertial confinement fusion implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weilacher, F.; Radha, P. B.; Forrest, C.

Neutron-based diagnostics are typically used to infer compressed core conditions such as areal density and ion temperature in deuterium–tritium (D–T) inertial confinement fusion (ICF) implosions. Asymmetries in the observed neutron-related quantities are important to understanding failure modes in these implosions. Neutrons from fusion reactions and their subsequent interactions including elastic scattering and neutron-induced deuteron breakup reactions are tracked to create spectra. Here, it is shown that background subtraction is important for inferring areal density from backscattered neutrons and is less important for the forward-scattered neutrons. A three-dimensional hydrodynamic simulation of a cryogenic implosion on the OMEGA Laser System [T. R.more » Boehly et al., Opt. Commun. 133, 495 (1997)] using the hydrodynamic code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] is post-processed using the tracking code IRIS3D. It is shown that different parts of the neutron spectrum from the view can be mapped into different regions of the implosion, enabling an inference of an areal-density map. It is also shown that the average areal-density and an areal-density map of the compressed target can be reconstructed with a finite number of detectors placed around the target chamber. Ion temperatures are inferred from the width of the D–D and D–T fusion neutron spectra. Backgrounds can significantly alter the inferred ion temperatures from the D–D reaction, whereas they insignificantly influence the inferred D–T ion temperatures for the areal densities typical of OMEGA implosions. Asymmetries resulting in fluid flow in the core are shown to influence the absolute inferred ion temperatures from both reactions, although relative inferred values continue to reflect the underlying asymmetry pattern. The work presented here is part of the wide range of the first set of studies performed with IRIS3D. Finally, this code will continue to be used for post-processing detailed hydrodynamic simulations and interpreting observed neutron spectra in ICF implosions.« less

Three-dimensional modeling of the neutron spectrum to infer plasma conditions in cryogenic inertial confinement fusion implosions

DOE PAGES

Weilacher, F.; Radha, P. B.; Forrest, C.

2018-04-26

Neutron-based diagnostics are typically used to infer compressed core conditions such as areal density and ion temperature in deuterium–tritium (D–T) inertial confinement fusion (ICF) implosions. Asymmetries in the observed neutron-related quantities are important to understanding failure modes in these implosions. Neutrons from fusion reactions and their subsequent interactions including elastic scattering and neutron-induced deuteron breakup reactions are tracked to create spectra. Here, it is shown that background subtraction is important for inferring areal density from backscattered neutrons and is less important for the forward-scattered neutrons. A three-dimensional hydrodynamic simulation of a cryogenic implosion on the OMEGA Laser System [T. R.more » Boehly et al., Opt. Commun. 133, 495 (1997)] using the hydrodynamic code HYDRA [M. M. Marinak et al., Phys. Plasmas 8, 2275 (2001)] is post-processed using the tracking code IRIS3D. It is shown that different parts of the neutron spectrum from the view can be mapped into different regions of the implosion, enabling an inference of an areal-density map. It is also shown that the average areal-density and an areal-density map of the compressed target can be reconstructed with a finite number of detectors placed around the target chamber. Ion temperatures are inferred from the width of the D–D and D–T fusion neutron spectra. Backgrounds can significantly alter the inferred ion temperatures from the D–D reaction, whereas they insignificantly influence the inferred D–T ion temperatures for the areal densities typical of OMEGA implosions. Asymmetries resulting in fluid flow in the core are shown to influence the absolute inferred ion temperatures from both reactions, although relative inferred values continue to reflect the underlying asymmetry pattern. The work presented here is part of the wide range of the first set of studies performed with IRIS3D. Finally, this code will continue to be used for post-processing detailed hydrodynamic simulations and interpreting observed neutron spectra in ICF implosions.« less

Magnetized Target Fusion in Advanced Propulsion Research

NASA Technical Reports Server (NTRS)

Cylar, Rashad

2003-01-01

The Magnetized Target Fusion (MTF) Propulsion lab at NASA Marshall Space Flight Center in Huntsville, Alabama has a program in place that has adopted to attempt to create a faster, lower cost and more reliable deep space transportation system. In this deep space travel the physics and development of high velocity plasma jets must be understood. The MTF Propulsion lab is also in attempt to open up the solar system for human exploration and commercial use. Fusion, as compared to fission, is just the opposite. Fusion involves the light atomic nuclei combination to produce denser nuclei. In the process, the energy is created by destroying the mass according to the distinguished equation: E = mc2 . Fusion energy development is being pursued worldwide as a very sustainable form of energy that is environmentally friendly. For the purposes of space exploration fusion reactions considered include the isotopes of hydrogen-deuterium (D2) and tritium (T3). Nuclei have an electrostatic repulsion between them and in order for the nuclei to fuse this repulsion must be overcome. One technique to bypass repulsion is to heat the nuclei to very high temperatures. The temperatures vary according to the type of reactions. For D-D reactions, one billion degrees Celsius is required, and for D-T reactions, one hundred million degrees is sufficient. There has to be energy input for useful output to be obtained form the fusion To make fusion propulsion practical, the mass, the volume, and the cost of the equipment to produce the reactions (generally called the reactor) need to be reduced by an order of magnitude or two from the state-of-the-art fusion machines. Innovations in fusion schemes are therefore required, especially for obtaining thrust for propulsive applications. Magnetized target fusion (MTF) is one of the innovative fusion concepts that have emerged over the last several years. MSFC is working with Los Alamos National Laboratory and other research groups in studying the underlying principles involved in MTF. Magnetized Target Fusion is an attempt to combine MCF (magnetic confinement fusion) for energy confinement and ICF (inertial confinement fusion) for efficient compression heating and wall free containment of the fusing plasma. It also seeks to combine the best features to these two main commonplace approaches to fusion.

Observed side feeding in incomplete fusion dynamics in 16O + 160Gd reaction at energy ∼5.6 MeV/A: Spin distribution measurements

NASA Astrophysics Data System (ADS)

Ali, Rahbar; Afzal Ansari, M.; Singh, D.; Kumar, Rakesh; Singh, D. P.; Sharma, M. K.; Gupta, Unnati; Singh, B. P.; Shidling, P. D.; Negi, Dinesh; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.

2017-12-01

Spin distributions of various residues populated via complete fusion (CF) and incomplete fusion (ICF) reactions in the interaction of 16O with 160Gd at the projectile energy Eproj ∼ 5.6 MeV/A have been studied. The experimentally measured spin distributions of the residues associated with the ICF reactions are found to be distinctly different from those populated via the CF reactions. An attempt has been made to extract the side-feeding pattern from the spin distributions of CF and ICF reaction products. It has been observed that the CF products are strongly fed over a broad spin range. But, no side-feeding takes place in the low observed spins as low partial waves are strongly hindered in the fast α-emission channels (associated with ICF) in the forward direction. It has also been observed that the mean input angular momentum for direct α-emitting (ICF) channels is relatively higher than evaporation α-emitting (CF) channels, and it increases with direct α-multiplicity in forward direction.

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

NASA Astrophysics Data System (ADS)

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 fuel-ablator interface, they cannot capture the effects of ion viscosity on the capsule compression, or effects associated with the interface, which are expected to be important. Studies of such effects are left for future work.

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

NASA Astrophysics Data System (ADS)

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.

Development of optics for x-ray phase-contrast imaging of high energy density plasmas.

PubMed

Stutman, D; Finkenthal, M; Moldovan, N

2010-10-01

Phase-contrast or refraction-enhanced x-ray radiography can be useful for the diagnostic of low-Z high energy density plasmas, such as imploding inertial confinement fusion (ICF) pellets, due to its sensitivity to density gradients. To separate and quantify the absorption and refraction contributions to x-ray images, methods based on microperiodic optics, such as shearing interferometry, can be used. To enable applying such methods with the energetic x rays needed for ICF radiography, we investigate a new type of optics consisting of grazing incidence microperiodic mirrors. Using such mirrors, efficient phase-contrast imaging systems could be built for energies up to ∼100 keV. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors based on the difference in the total reflection between a low-Z substrate and a high-Z film. Prototype mirrors fabricated with this method show promising characteristics in laboratory tests.

Rapid measurement and compensation method of eccentricity in automatic profile measurement of the ICF capsule.

PubMed

Li, Shaobai; Wang, Yun; Wang, Qi; Ma, Xianxian; Wang, Longxiao; Zhao, Weiqian; Zhang, Xusheng

2018-05-10

In this paper, we propose a new measurement and compensation method for the eccentricity of the inertial confinement fusion (ICF) capsule, which combines computer vision and the laser differential confocal method to align the capsule in rotation measurement. This technique measures the eccentricity of the capsule by obtaining the sub-pixel profile with a moment-based algorithm, then performs the preliminary alignment by the two-dimensional adjustment. Next, we use the laser differential confocal sensor to measure the height data of the equatorial surface of the capsule by turning it around, then obtain and compensate the remaining eccentricity ultimately. This method is a non-contact, automatic, rapid, high-precision measurement and compensation technique of eccentricity for the capsule. Theoretical analyses and preliminary experiments indicate that the maximum measurement range of eccentricity of this proposed method is 1.8 mm for the capsule with a diameter of 1 mm, and it could eliminate the eccentricity to less than 0.5 μm in 30 s.

Return current instability driven by a temperature gradient in ICF plasmas

DOE PAGES

Rozmus, W.; Brantov, A. V.; Sherlock, M.; ...

2017-10-12

Here, hot plasmas with strong temperature gradients in inertial confinement fusion (ICF) experiments are examined for ion acoustic instabilities produced by electron heat flow. The return current instability (RCI) due to a neutralizing current of cold electrons arising in response to a large electron heat flux has been considered. First, the linear threshold and growth rates are derived in the nonlocal regime of thermal transport. They are compared with the results of Vlasov-Fokker-Planck (VFP) simulations in one spatial dimension. Very good agreement has been found between kinetic VFP simulations and the linear theory of the RCI. A quasi-stationary state ofmore » ion acoustic turbulence produced by the RCI is achieved in the VFP simulations. Saturation of the RCI involves heating of ions in the tail of the ion distribution function and convection of the enhanced ion acoustic fluctuations from the unstable region of the plasma. Further evolution of the ion acoustic turbulence and its effects on absorption and transport are also discussed.« less

Low-stress mounting configuration design for large aperture laser transport mirror

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Quan, Xusong; Yao, Chao; Wang, Hui

2016-10-01

TM1-6S1 large aperture laser transport mirror is a crucial optical unit of high power solid-state laser in the Inertial Confinement Fusion (ICF) facility. This article focuses on the low-stress and precise mounting method of large-aperture mirror. Based on the engineering practice of SG-III, the state-of-the-art and key problems of current mounting configuration are clarified firstly. Subsequently, a brand new low-stress mounting configuration with flexure supports is proposed. Opto-mechanical model of the mirror under mounting force is built up with elastic mechanics theory. Further, numerical methods and field tests are employed to verify the favorable load uniform capacity and load adjust capacity of flexure supports. With FEM, the relation between the mounting force from new configuration and the mirror surface distortion (wavefront error) is clarified. The novel mounting method of large aperture optics could be not only used on this laser transport mirror, but also on the other transmission optics and large crystals in ICF facilities.

Design and fabrication of x-ray Kirkpatrick-Baez microscope for ICF

NASA Astrophysics Data System (ADS)

Mu, Baozhong; Wang, Zhanshan; Huang, Shengling; Yi, Shengzhen; Shen, Zhengxiang

2007-12-01

A hard x-ray (8 keV, Kα line of Cu) Kirkpatrick-Baez (KB) microscope was designed for the diagnostics of inertial confinement fusion (ICF). Three main parts including optical design, fabrication of multilayers, and alignment method were discussed in this paper. According to the deduced equation of aberration in whole field, an optical system was designed, which gives attention to not only spatial resolution but also the collection efficiency. Tungsten (W) and boron carbide (B4C) were chosen as multilayer materials and the non-periodic multilayer with 40 layers was deposited. The measured reflectivity by XRD is better than 18% in the bandwidth range of about 0.3%. Super accurately alignment is another difficulty in the application of KB microscope. To meet the requirements of pointing and co-focusing, a binocular laser pointer which is flexible enough was designed. Finally, an 8keV x-ray tube was used as source in x-ray imaging experiment and images with magnification of 2× were obtained.

Method of forming a continuous polymeric skin on a cellular foam material

DOEpatents

Duchane, David V.; Barthell, Barry L.

1985-01-01

Hydrophobic cellular material is coated with a thin hydrophilic polymer skin which stretches tightly over the outer surface of the foam but which does not fill the cells of the foam, thus resulting in a polymer-coated foam structure having a smoothness which was not possible in the prior art. In particular, when the hydrophobic cellular material is a specially chosen hydrophobic polymer foam and is formed into arbitrarily chosen shapes prior to the coating with hydrophilic polymer, inertial confinement fusion (ICF) targets of arbitrary shapes can be produced by subsequently coating the shapes with metal or with any other suitable material. New articles of manufacture are produced, including improved ICF targets, improved integrated circuits, and improved solar reflectors and solar collectors. In the coating method, the cell size of the hydrophobic cellular material, the viscosity of the polymer solution used to coat, and the surface tensin of the polymer solution used to coat are all very important to the coating.

Metal Alloy ICF Capsules Created by Electrodeposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horwood, Corie; Stadermann, Michael; Bunn, Thomas L.

Electrochemical deposition is an attractive alternative to physical vapor deposition and micromachining to produce metal capsules for inertial confinement fusion (ICF). Electrochemical deposition (also referred to as electrodeposition or plating) is expected to produce full-density metal capsules without seams or inclusions of unwanted atomic constituents, the current shortcomings of micromachine and physical vapor deposition, respectively. In this paper, we discuss new cathode designs that allow for the rapid electrodeposition of gold and copper alloys on spherical mandrels by making transient contact with the constantly moving spheres. Electrodeposition of pure gold, copper, platinum, and alloys of gold-copper and gold-silver are demonstrated,more » with nonporous coatings of >40 µm achieved in only a few hours of plating. The surface roughness of the spheres after electrodeposition is comparable to the starting mandrel, and the coatings appear to be fully dense with no inclusions. A detailed understanding of the electrodeposition conditions that result in different alloy compositions and plating rates will allow for the electrodeposition of graded alloys on spheres in the near future. Finally, this report on the electrodeposition of metals on spherical mandrels is an important first step toward the fabrication of graded-density metal capsules for ICF experiments at the National Ignition Facility.« less

AXIS: an instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF.

PubMed

Hall, G N; Izumi, N; Tommasini, R; Carpenter, A C; Palmer, N E; Zacharias, R; Felker, B; Holder, J P; Allen, F V; Bell, P M; Bradley, D; Montesanti, R; Landen, O L

2014-11-01

Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV-200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

Metal Alloy ICF Capsules Created by Electrodeposition

DOE PAGES

Horwood, Corie; Stadermann, Michael; Bunn, Thomas L.

2017-12-04

Electrochemical deposition is an attractive alternative to physical vapor deposition and micromachining to produce metal capsules for inertial confinement fusion (ICF). Electrochemical deposition (also referred to as electrodeposition or plating) is expected to produce full-density metal capsules without seams or inclusions of unwanted atomic constituents, the current shortcomings of micromachine and physical vapor deposition, respectively. In this paper, we discuss new cathode designs that allow for the rapid electrodeposition of gold and copper alloys on spherical mandrels by making transient contact with the constantly moving spheres. Electrodeposition of pure gold, copper, platinum, and alloys of gold-copper and gold-silver are demonstrated,more » with nonporous coatings of >40 µm achieved in only a few hours of plating. The surface roughness of the spheres after electrodeposition is comparable to the starting mandrel, and the coatings appear to be fully dense with no inclusions. A detailed understanding of the electrodeposition conditions that result in different alloy compositions and plating rates will allow for the electrodeposition of graded alloys on spheres in the near future. Finally, this report on the electrodeposition of metals on spherical mandrels is an important first step toward the fabrication of graded-density metal capsules for ICF experiments at the National Ignition Facility.« less

Pulsed x-ray sources for characterization of gated framing cameras

NASA Astrophysics Data System (ADS)

Filip, Catalin V.; Koch, Jeffrey A.; Freeman, Richard R.; King, James A.

2017-08-01

Gated X-ray framing cameras are used to measure important characteristics of inertial confinement fusion (ICF) implosions such as size and symmetry, with 50 ps time resolution in two dimensions. A pulsed source of hard (>8 keV) X-rays, would be a valuable calibration device, for example for gain-droop measurements of the variation in sensitivity of the gated strips. We have explored the requirements for such a source and a variety of options that could meet these requirements. We find that a small-size dense plasma focus machine could be a practical single-shot X-ray source for this application if timing uncertainties can be overcome.

The proceedings of the 1st international workshop on laboratory astrophysics experiments with large lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Remington, B.A.; Goldstein, W.H.

1996-08-09

The world has stood witness to the development of a number of highly sophisticated and flexible, high power laser facilities (energies up to 50 kJ and powers up to 50 TW), driven largely by the world-wide effort in inertial confinement fusion (ICF). The charter of diagnosing implosions with detailed, quantitative measurements has driven the ICF laser facilities to be exceedingly versatile and well equipped with diagnostics. Interestingly, there is considerable overlap in the physics of ICF and astrophysics. Both typically involve compressible radiative hydrodynamics, radiation transport, complex opacities, and equations of state of dense matter. Surprisingly, however, there has beenmore » little communication between these two communities to date. With the recent declassification of ICF in the USA, and the approval to commence with construction of the next generation ``superlasers``, the 2 MJ National Ignition Facility in the US, and its equivalent, the LMJ laser in France, the situation is ripe for change. . Given the physics similarities that exist between ICF and astrophysics, one strongly suspects that there should exist regions of overlap where supporting research on the large lasers could be beneficial to the astrophysics community. As a catalyst for discussions to this end, Lawrence Livermore National Laboratory sponsored this workshop. Approximately 100 scientists attended from around the world, representing eight countries: the USA, Canada, UK, France, Germany, Russia, Japan, and Israel. A total of 30 technical papers were presented. The two day workshop was divided into four sessions, focusing on nonlinear hydrodynamics, radiative hydrodynamics, radiation transport, and atomic physics-opacities. Copies of the presentations are contained in these proceedings.« less

Cryogenic hydrogen fuel for controlled inertial confinement fusion (formation of reactor-scale cryogenic targets)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aleksandrova, I. V.; Koresheva, E. R., E-mail: elena.koresheva@gmail.com; Krokhin, O. N.

2016-12-15

In inertial fusion energy research, considerable attention has recently been focused on low-cost fabrication of a large number of targets by developing a specialized layering module of repeatable operation. The targets must be free-standing, or unmounted. Therefore, the development of a target factory for inertial confinement fusion (ICF) is based on methods that can ensure a cost-effective target production with high repeatability. Minimization of the amount of tritium (i.e., minimization of time and space at all production stages) is a necessary condition as well. Additionally, the cryogenic hydrogen fuel inside the targets must have a structure (ultrafine layers—the grain sizemore » should be scaled back to the nanometer range) that supports the fuel layer survivability under target injection and transport through the reactor chamber. To meet the above requirements, significant progress has been made at the Lebedev Physical Institute (LPI) in the technology developed on the basis of rapid fuel layering inside moving free-standing targets (FST), also referred to as the FST layering method. Owing to the research carried out at LPI, unique experience has been gained in the development of the FST-layering module for target fabrication with an ultrafine fuel layer, including a reactor- scale target design. This experience can be used for the development of the next-generation FST-layering module for construction of a prototype of a target factory for power laser facilities and inertial fusion power plants.« less

Assessment of ion kinetic effects in shock-driven inertial confinement fusion (ICF) implosions using fusion burn imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenberg, M. J.; Séguin, F. H.; Amendt, P. A.

The significance and nature of ion kinetic effects in D³He-filled, shock-driven inertial confinement fusion implosions are assessed through measurements of fusion burn profiles. Over this series of experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number, N K) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially resolvedmore » measurements of the fusion burn are used to examine kinetic ion transport effects in greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison of measured and simulated burn profiles shows that models including ion transport effects are able to better match the experimental results. In implosions characterized by large Knudsen numbers (N K ~ 3), the fusion burn profiles predicted by hydrodynamics simulations that exclude ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that includes a model of ion diffusion is able to qualitatively match the measured profile shapes. Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the observed trends, though further refinement of the models is needed for a more complete and quantitative understanding of ion kinetic effects.« less

Assessment of ion kinetic effects in shock-driven inertial confinement fusion (ICF) implosions using fusion burn imaging

DOE PAGES

Rosenberg, M. J.; Séguin, F. H.; Amendt, P. A.; ...

2015-06-02

The significance and nature of ion kinetic effects in D³He-filled, shock-driven inertial confinement fusion implosions are assessed through measurements of fusion burn profiles. Over this series of experiments, the ratio of ion-ion mean free path to minimum shell radius (the Knudsen number, N K) was varied from 0.3 to 9 in order to probe hydrodynamic-like to strongly kinetic plasma conditions; as the Knudsen number increased, hydrodynamic models increasingly failed to match measured yields, while an empirically-tuned, first-step model of ion kinetic effects better captured the observed yield trends [Rosenberg et al., Phys. Rev. Lett. 112, 185001 (2014)]. Here, spatially resolvedmore » measurements of the fusion burn are used to examine kinetic ion transport effects in greater detail, adding an additional dimension of understanding that goes beyond zero-dimensional integrated quantities to one-dimensional profiles. In agreement with the previous findings, a comparison of measured and simulated burn profiles shows that models including ion transport effects are able to better match the experimental results. In implosions characterized by large Knudsen numbers (N K ~ 3), the fusion burn profiles predicted by hydrodynamics simulations that exclude ion mean free path effects are peaked far from the origin, in stark disagreement with the experimentally observed profiles, which are centrally peaked. In contrast, a hydrodynamics simulation that includes a model of ion diffusion is able to qualitatively match the measured profile shapes. Therefore, ion diffusion or diffusion-like processes are identified as a plausible explanation of the observed trends, though further refinement of the models is needed for a more complete and quantitative understanding of ion kinetic effects.« less

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

NASA Astrophysics Data System (ADS)

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.

Yb:YAG ceramic-based laser driver for Inertial Fusion Energy (IFE)

NASA Astrophysics Data System (ADS)

Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.

2016-03-01

We report on a new class of laser amplifiers for inertial confinement fusion (ICF) drivers based on a Yb:YAG ceramic disk in an edge-pumped configuration and cooled by a high-velocity gas flow. The Yb lasant offers very high efficiency and low waste heat. The ceramic host material has a thermal conductivity nearly 15-times higher than the traditionally used glass and it is producible in sizes suitable for a typical 10- to 20-kJ driver beam line. The combination of high lasant efficiency, low waste heat, edge-pumping, and excellent thermal conductivity of the host, enable operation at 10 to 20 Hz at over 20% wall plug efficiency while being comparably smaller and less costly than recently considered face-pumped alternative drivers using Nd:glass, Yb:S-FAP, and cryogenic Yb:YAG. Scalability of the laser driver over a broad range of sizes is presented.

Advances in HYDRA and its application to simulations of Inertial Confinement Fusion targets

NASA Astrophysics Data System (ADS)

Marinak, M. M.; Kerbel, G. D.; Koning, J. M.; Patel, M. V.; Sepke, S. M.; Brown, P. N.; Chang, B.; Procassini, R.; Veitzer, S. A.

2008-11-01

We will outline new capabilities added to the HYDRA 2D/3D multiphysics ICF simulation code. These include a new SN multigroup radiation transport package (1D), constitutive models for elastic-plastic (strength) effects, and a mix model. A Monte Carlo burn package is being incorporated to model diagnostic signatures of neutrons, gamma rays and charged particles. A 3D MHD package that treats resistive MHD is available. Improvements to HYDRA's implicit Monte Carlo photonics package, including the addition of angular biasing, now enable integrated hohlraum simulations to complete in substantially shorter time. The heavy ion beam deposition package now includes a new model for ion stopping power developed by the Tech-X Corporation, with improved accuracy below the Bragg peak. Examples will illustrate HYDRA's enhanced capabilities to simulate various aspects of inertial confinement fusion targets.This work was performed under the auspices of the Lawrence Livermore National Security, LLC, (LLNS) under Contract No. DE-AC52-07NA27344. The work of Tech-X personnel was funded by the Department of Energy under Small Business Innovation Research Contract No. DE-FG02-03ER83797.

Stability of stagnation via an expanding accretion shock wave

NASA Astrophysics Data System (ADS)

Velikovich, A. L.; Murakami, M.; Taylor, B. D.; Giuliani, J. L.; Zalesak, S. T.; Iwamoto, Y.

2016-05-01

Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave is ubiquitous in inertial confinement fusion (ICF) and high-energy-density plasma physics, the examples ranging from plasma flows in x-ray-generating Z pinches [Maron et al., Phys. Rev. Lett. 111, 035001 (2013)] to the experiments in support of the recently suggested concept of impact ignition in ICF [Azechi et al., Phys. Rev. Lett. 102, 235002 (2009); Murakami et al., Nucl. Fusion 54, 054007 (2014)]. Some experimental evidence indicates that stagnation via an expanding shock wave is stable, but its stability has never been studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock front and is described by the classic ideal-gas Noh solution in spherical and cylindrical geometry. In either case, the stagnated flow has been demonstrated to be stable, initial perturbations exhibiting a power-law, oscillatory or monotonic, decay with time for all the eigenmodes. This conclusion has been supported by our simulations done both on a Cartesian grid and on a curvilinear grid in spherical coordinates. Dispersion equation determining the eigenvalues of the problem and explicit formulas for the eigenfunction profiles corresponding to these eigenvalues are presented, making it possible to use the theory for hydrocode verification in two and three dimensions.

Canonical Descriptions of High Intensity Laser-Plasma Interaction

NASA Astrophysics Data System (ADS)

Le Cornu, B. J.

The problem of laser-plasma interaction has been studied extensively in the context of inertial confinement fusion (ICF). These studies have focussed on effects like the nonlinear force, self-focusing, Rayleigh- Taylor instabilities, stimulated Brillouin scattering and stimulated Raman scattering observed in ICF schemes. However, there remains a large discrepancy between theory and experiment in the context of nuclear fusion schemes. Several authors have attempted to gain greater understanding of the physics involved by the application of standard or 'canonical' methods used in Lagrangian and Hamiltonian mechanics to the problem of plasma physics. This thesis presents a new canonical description of laser-plasma interaction based on the Podolsky Lagrangian. Finite self-energy of charged particles, incroporation of high-frequency effects and an ability to quantise are the main advantages of this new model. The nature of the Podolsky constant is also analysed in the context of plasma physics, specifically in terms of the plasma dispersion relation. A new gauge invariant expression of the energy-momentum tensor for any gauge invariant Lagrangian dependent on second order derivatives is derived for the first time. Finally, the transient and nontransient expressions of the nonlinear ponderomotive force in laser-plasma interaction are discussed and shown to be closely approximated by a canonical derivation of the electromagnetic Lagrangian, a fact that seems to have been missed in the literature.

Stability of stagnation via an expanding accretion shock wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velikovich, A. L.; Giuliani, J. L.; Murakami, M.

Stagnation of a cold plasma streaming to the center or axis of symmetry via an expanding accretion shock wave is ubiquitous in inertial confinement fusion (ICF) and high-energy-density plasma physics, the examples ranging from plasma flows in x-ray-generating Z pinches [Maron et al., Phys. Rev. Lett. 111, 035001 (2013)] to the experiments in support of the recently suggested concept of impact ignition in ICF [Azechi et al., Phys. Rev. Lett. 102, 235002 (2009); Murakami et al., Nucl. Fusion 54, 054007 (2014)]. Some experimental evidence indicates that stagnation via an expanding shock wave is stable, but its stability has never beenmore » studied theoretically. We present such analysis for the stagnation that does not involve a rarefaction wave behind the expanding shock front and is described by the classic ideal-gas Noh solution in spherical and cylindrical geometry. In either case, the stagnated flow has been demonstrated to be stable, initial perturbations exhibiting a power-law, oscillatory or monotonic, decay with time for all the eigenmodes. This conclusion has been supported by our simulations done both on a Cartesian grid and on a curvilinear grid in spherical coordinates. Dispersion equation determining the eigenvalues of the problem and explicit formulas for the eigenfunction profiles corresponding to these eigenvalues are presented, making it possible to use the theory for hydrocode verification in two and three dimensions.« less

Starlight: A stationary inertial-confinement-fusion reactor with nonvaporizing walls

NASA Astrophysics Data System (ADS)

Pitts, John H.

1989-09-01

The Starlight concept for an inertial-confinement-fusion (ICF) reactor utilizes a softball-sized solid-lithium x ray and debris shield that surrounds each fuel pellet as it is injected into the reactor. The shield is sacrificial and vaporizes as it absorbs x ray and ion-debris energy emanating from the fusion reactions in the fuel pellets. However, the energy deposition time at the surface if the first wall is lengthened by four orders of magnitude (to greater than 100 microns) which allows the energy to be conducted into the wall fast enough to prevent vaporization. Starlight operates at 5 Hz with 300-MJ-yield fuel pellets. It features a stationary, nonvaporizing first wall that eliminates erosion and shock waves which can destroy the wall; also, it allows arbitrary fuel pellet illumination geometries so that efficient coupling of either laser or heavy ion beam driver energy to the fuel pellet can be achieved. When neutrons penetrate the shield, the wall experiences neutron damage that limits its lifetime. Hence, we must choose wall materials that have ab economic lifetime. We describe the general concept and a specific design for laser drivers using a 6-m-radius, 2 1/4 Cr 1 Mo steel first wall. We include heat transfer calculations used to establish the radius and structural analysis that shows stresses are within allowable limits. A wall lifetime of over six years is predicted.

Hybrid-drive implosion system for ICF targets

DOEpatents

Mark, James W.

1988-08-02

Hybrid-drive implosion systems (20,40) for ICF targets (10,22,42) are described which permit a significant increase in target gain at fixed total driver energy. The ICF target is compressed in two phases, an initial compression phase and a final peak power phase, with each phase driven by a separate, optimized driver. The targets comprise a hollow spherical ablator (12) surroundingly disposed around fusion fuel (14). The ablator is first compressed to higher density by a laser system (24), or by an ion beam system (44), that in each case is optimized for this initial phase of compression of the target. Then, following compression of the ablator, energy is directly delivered into the compressed ablator by an ion beam driver system (30,48) that is optimized for this second phase of operation of the target. The fusion fuel (14) is driven, at high gain, to conditions wherein fusion reactions occur. This phase separation allows hydrodynamic efficiency and energy deposition uniformity to be individually optimized, thereby securing significant advantages in energy gain. In additional embodiments, the same or separate drivers supply energy for ICF target implosion.

Hybrid-drive implosion system for ICF targets

DOEpatents

Mark, James W.

1988-01-01

Hybrid-drive implosion systems (20,40) for ICF targets (10,22,42) are described which permit a significant increase in target gain at fixed total driver energy. The ICF target is compressed in two phases, an initial compression phase and a final peak power phase, with each phase driven by a separate, optimized driver. The targets comprise a hollow spherical ablator (12) surroundingly disposed around fusion fuel (14). The ablator is first compressed to higher density by a laser system (24), or by an ion beam system (44), that in each case is optimized for this initial phase of compression of the target. Then, following compression of the ablator, energy is directly delivered into the compressed ablator by an ion beam driver system (30,48) that is optimized for this second phase of operation of the target. The fusion fuel (14) is driven, at high gain, to conditions wherein fusion reactions occur. This phase separation allows hydrodynamic efficiency and energy deposition uniformity to be individually optimized, thereby securing significant advantages in energy gain. In additional embodiments, the same or separate drivers supply energy for ICF target implosion.

Hybrid-drive implosion system for ICF targets

DOEpatents

Mark, J.W.K.

1987-10-14

Hybrid-drive implosion systems for ICF targets are described which permit a significant increase in target gain at fixed total driver energy. The ICF target is compressed in two phases, an initial compression phase and a final peak power phase, with each phase driven by a separate, optimized driver. The targets comprise a hollow spherical ablator surroundingly disposed around fusion fuel. The ablator is first compressed to higher density by a laser system, or by an ion beam system, that in each case is optimized for this initial phase of compression of the target. Then, following compression of the ablator, energy is directly delivered into the compressed ablator by an ion beam driver system that is optimized for this second phase of operation of the target. The fusion fuel is driven, at high gain, to conditions wherein fusion reactions occur. This phase separation allows hydrodynamic efficiency and energy deposition uniformity to be individually optimized, thereby securing significant advantages in energy gain. In additional embodiments, the same or separate drivers supply energy for ICF target implosion. 3 figs.

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

NASA Astrophysics Data System (ADS)

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.

Damage behavior of Nd:glass of high-power disk amplifier medium in ICF Facility

NASA Astrophysics Data System (ADS)

He, Shaobo; Chen, Lin; Yuan, Xiaodong; Chen, Yuanbin; Cheng, Xiaofeng; Xie, Xudong; Wang, Wenyi; Zu, Xiaotao

2016-12-01

Large aperture Nd:glass disk is often used as the amplifier medium in the inertial confinement fusion (ICF) facilities. The typical size of Nd:glass is up to 810mm×460mm×40mm and more than 3,000 Nd:glass components are needed in the ICF facility. At present, the 3ω fused silica glass and DKDP crystal are mainly responsible for the damage of driver used for ICF. However, with the enlargement of the facility and increase of laser shot number, the laser damage of Nd:glass at 1ω waveband is still an important problem to limit the stable operation of facility and improvement of laser beam quality. In this work, the influence of Nd:glass material itself, mechanical processing, service environment, and laser beam quality on its damage behavior is investigated experimentally and theoretically. The results and conclusions can be summarized as follows: (1) It is very important to control the concentration of platinum impurity particles during melting and the sputtering effect of the cladding materials. (2) The number and length of fractural and brittle scratches should be strictly suppressed during mechanical processing of Nd:glass. (3) The B-integral of high power laser beam should be rigorously controlled. Particularly, the top shape of pulses must be well controlled when operating at high peak laser power. (4) The service environment should be well managed to make sure the cleanness of the surface of Nd:glass better than 100/A level during mounting and running. (5) The service environment and beam quality should be monitored during operation.

Impact of flows on ion temperatures inferred from neutron spectra in asymmetrically driven OMEGA DT implosions

NASA Astrophysics Data System (ADS)

Gatu Johnson, M.; Frenje, J. A.; Seguin, F. H.; Petrasso, R. D.; Aappelbe, B.; Chittenden, J.; Walsh, C.; Knauer, J. P.; Glebov, V. Yu.; Forrest, C.; Marshall, F.; Michel, T.; Stoeckl, C.; Sangster, T. C.; Zylstra, A.

2016-10-01

Ion temperatures (Tion) in Inertial Confinement Fusion (ICF) experiments have traditionally been inferred from the broadening of primary neutron spectra. Directional motion (flow) of the fuel at burn, expected to arise due to asymmetries imposed by engineering features (such as stalks, fill tubes, tents, or capsule imperfections) or drive non-uniformity, also impacts broadening and may lead to artificially inflated ``Tion'' values. Flow due to low-mode asymmetries is expected to give rise to line-of-sight variations in measured Tion, as observed in OMEGA cryogenic DT implosions but not in similar experiments at the NIF. In this presentation we report on an OMEGA experiment with intentionally asymmetric drive, designed to test the ability to accurately predict and measure line-of-sight differences in apparent Tion due to low-mode asymmetry-seeded flows. The results provide insight into the complexity of hot-spot dynamics, which is a problem that must be mastered to achieve ICF ignition. This work was supported in part by LLE, the U.S. DoE (NNSA, NLUF) and LLNL.

Data driven models of the performance and repeatability of NIF high foot implosions

NASA Astrophysics Data System (ADS)

Gaffney, Jim; Casey, Dan; Callahan, Debbie; Hartouni, Ed; Ma, Tammy; Spears, Brian

2015-11-01

Recent high foot (HF) inertial confinement fusion (ICF) experiments performed at the national ignition facility (NIF) have consisted of enough laser shots that a data-driven analysis of capsule performance is feasible. In this work we use 20-30 individual implosions of similar design, spanning laser drive energies from 1.2 to 1.8 MJ, to quantify our current understanding of the behavior of HF ICF implosions. We develop a probabilistic model for the projected performance of a given implosion and use it to quantify uncertainties in predicted performance including shot-shot variations and observation uncertainties. We investigate the statistical significance of the observed performance differences between different laser pulse shapes, ablator materials, and capsule designs. Finally, using a cross-validation technique, we demonstrate that 5-10 repeated shots of a similar design are required before real trends in the data can be distinguished from shot-shot variations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-674957.

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

NASA Astrophysics Data System (ADS)

Swadling, G. F.; Ross, J. S.; Datte, P.; Moody, J.; Divol, L.; Jones, O.; Landen, O.

2016-11-01

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ˜8 J cm-2. This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 1019 cm-2 Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic.

PubMed

Swadling, G F; Ross, J S; Datte, P; Moody, J; Divol, L; Jones, O; Landen, O

2016-11-01

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm -2 . This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

Pulse shaping system

DOEpatents

Skeldon, Mark D.; Letzring, Samuel A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Pulse shaping system

DOEpatents

Skeldon, M.D.; Letzring, S.A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

AXIS: An instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, G. N., E-mail: hall98@llnl.gov; Izumi, N.; Tommasini, R.

2014-11-15

Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detectormore » for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV–200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.« less

The National Ignition Facility modular Kirkpatrick-Baez microscope

DOE PAGES

Pickworth, L. A.; Ayers, J.; Bell, P.; ...

2016-08-10

Current two-dimensional X-ray imaging at the National Ignition Facility (NIF) uses time resolved pinhole cameras with ~10-25µm pinholes. This method has limitations in the smallest resolvable features that can be imaged with reasonable photon statistics for inertial confinement fusion (ICF) applications. ICF sources have a broadband self-emission spectrum that causes the pinhole images obtained, through thin foil filters, to contain a similarly broadband spectrum complicating the interpretation of structure in the source. In order to study phenomena on the scale of ~5 µm, such as dopant mix in the ICF capsule, a narrow energy band, higher spatial resolution microscope systemmore » with improved signal/noise has been developed using X-ray optics. Utilizing grazing incidence mirrors in a Kirkpatrick-Baez microscope (KBM) configuration, an X-ray microscope has been designed and fielded on NIF with four imaging channels. The KBM has ~12x magnification, <8 µm resolution and higher throughput in comparison to similar pinhole systems. The first KBM mirrors are coated with a multilayer mirror to allow a ‘narrow band’ energy response at 10.2keV with ΔE~3keV. By adjusting the mirror coating only, the energy response can be matched to future experimental requirements. Here, several mirror packs have been commissioned and are interchangeable in the diagnostic snout.« less

The National Ignition Facility modular Kirkpatrick-Baez microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickworth, L. A.; Ayers, J.; Bell, P.

Current two-dimensional X-ray imaging at the National Ignition Facility (NIF) uses time resolved pinhole cameras with ~10-25µm pinholes. This method has limitations in the smallest resolvable features that can be imaged with reasonable photon statistics for inertial confinement fusion (ICF) applications. ICF sources have a broadband self-emission spectrum that causes the pinhole images obtained, through thin foil filters, to contain a similarly broadband spectrum complicating the interpretation of structure in the source. In order to study phenomena on the scale of ~5 µm, such as dopant mix in the ICF capsule, a narrow energy band, higher spatial resolution microscope systemmore » with improved signal/noise has been developed using X-ray optics. Utilizing grazing incidence mirrors in a Kirkpatrick-Baez microscope (KBM) configuration, an X-ray microscope has been designed and fielded on NIF with four imaging channels. The KBM has ~12x magnification, <8 µm resolution and higher throughput in comparison to similar pinhole systems. The first KBM mirrors are coated with a multilayer mirror to allow a ‘narrow band’ energy response at 10.2keV with ΔE~3keV. By adjusting the mirror coating only, the energy response can be matched to future experimental requirements. Here, several mirror packs have been commissioned and are interchangeable in the diagnostic snout.« less

The National Ignition Facility modular Kirkpatrick-Baez microscope.

PubMed

Pickworth, L A; Ayers, J; Bell, P; Brejnholt, N F; Buscho, J G; Bradley, D; Decker, T; Hau-Riege, S; Kilkenny, J; McCarville, T; Pardini, T; Vogel, J; Walton, C

2016-11-01

Current two-dimensional X-ray imaging at the National Ignition Facility (NIF) uses time resolved pinhole cameras with ∼10-25 μm pinholes. This method has limitations in the smallest resolvable features that can be imaged with reasonable photon statistics for inertial confinement fusion (ICF) applications. ICF sources have a broadband self-emission spectrum that causes the pinhole images obtained, through thin foil filters, to contain a similarly broadband spectrum complicating the interpretation of structure in the source. In order to study phenomena on the scale of ∼5 μm, such as dopant mix in the ICF capsule, a narrow energy band, higher spatial resolution microscope system with improved signal/noise has been developed using X-ray optics. Utilizing grazing incidence mirrors in a Kirkpatrick-Baez microscope (KBM) configuration [P. Kirkpatrick and A. V. Baez, J. Opt. Soc. Am. 38, 766-774 (1948)], an X-ray microscope has been designed and fielded on NIF with four imaging channels. The KBM has ∼12 × magnification, <8 μm resolution, and higher throughput in comparison to similar pinhole systems. The first KBM mirrors are coated with a multilayer mirror to allow a "narrow band" energy response at 10.2 keV with ΔE ∼ 3 keV. By adjusting the mirror coating only, the energy response can be matched to the future experimental requirements. Several mirror packs have been commissioned and are interchangeable in the diagnostic snout.

Role of partial linear momentum transfer on incomplete fusion reaction

NASA Astrophysics Data System (ADS)

Ali, Sabir; Ahmad, Tauseef; Kumar, Kamal; Gull, Muntazir; Rizvi, I. A.; Agarwal, Avinash; Ghugre, S. S.; Sinha, A. K.; Chaubey, A. K.

2018-04-01

Measurements of forward recoil range distributions (FRRDs) of the evaporation residues, populated in the 20Ne+51V reaction at E_{lab}≈ 145 MeV, have been carried out using the offline characteristic γ-ray detection method. The observation does corroborate the presence of complete fusion (CF) process in the population of p xn channel residues and both complete as well as incomplete fusion (ICF) processes in the population of α emitting channel residues. The FRRDs of p xn channel residues comprise single peak only, whereas α emitting channel residues have multiple peaks in their FRRDs. CF cross section data were used to extract the fusion functions. Extracted fusion functions were found to be suppressed with respect to the universal fusion function which is used as a uniform standard reference. The observed contribution arising from the ICF process in the population of α emitting channel residues is explained in terms of breakup fusion model.

Anomalous DD and TT yields relative to the DT yield in inertial-confinement-fusion implosions

NASA Astrophysics Data System (ADS)

Casey, Daniel T.

2011-10-01

Measurements of the D(d,p)T (DD), T(t,2n)4He (TT) and D(t,n)4He (DT) reactions have been conducted using deuterium-tritium gas-filled inertial confinement fusion (ICF) implosions. In these experiments, which were carried out at the OMEGA laser facility, absolute spectral measurements of the DD protons and TT neutrons were conducted and compared to neutron-time-of-flight measured DT-neutron yields. From these measurements, it is concluded that the DD yield is anomalously low and the TT yield is anomalously high relative to the DT yield, an effect that is enhanced with increasing ion temperature. These results can be explained by an enrichment of tritium in the core of an ICF implosion, which may be present in ignition experiments planned on the National Ignition Facility. In addition, the spectral measurements of the TT-neutron spectrum were conducted for the first time at reactant central-mass energies in the range of 15-30 keV. The results from these measurements indicate that the TT reaction proceeds primarily through the direct three-body reaction channel, producing a continuous TT-neutron spectrum in the range 0 - 9.5 MeV. This work was conducted in collaboration with J. A. Frenje, M. Gatu Johnson, M. J.-E. Manuel, H. G. Rinderknecht, N. Sinenian, F. H. Seguin, C. K. Li, R. D. Petrasso, P. B. Radha, J. A. Delettrez, V. Yu Glebov, D. D. Meyerhofer, T. C. Sangster, D. P. McNabb, P. A. Amendt, R. N. Boyd, J. R. Rygg, H. W. Herrmann, Y. H. Kim, G. P. Grim and A. D. Bacher. This work was supported in part by the U.S. Department of Energy (Grant No. DE-FG03-03SF22691), LLE (subcontract Grant No. 412160-001G), LLNL (subcontract Grant No. B504974).

First-principles opacity table of warm dense deuterium for inertial-confinement-fusion applications.

PubMed

Hu, S X; Collins, L A; Goncharov, V N; Boehly, T R; Epstein, R; McCrory, R L; Skupsky, S

2014-09-01

Accurate knowledge of the optical properties of a warm dense deuterium-tritium (DT) mixture is important for reliable design of inertial confinement fusion (ICF) implosions using radiation-hydrodynamics simulations. The opacity of a warm dense DT shell essentially determines how much radiation from hot coronal plasmas can be deposited in the DT fuel of an imploding capsule. Even for the simplest species of hydrogen, the accurate calculation of their opacities remains a challenge in the warm-dense matter regime because strong-coupling and quantum effects play an important role in such plasmas. With quantum-molecular-dynamics (QMD) simulations, we have derived a first-principles opacity table (FPOT) of deuterium (and the DT mixture by mass scaling) for a wide range of densities from ρ(D)=0.5 to 673.518g/cm(3) and temperatures from T=5000K up to the Fermi temperature T(F) for each density. Compared with results from the astrophysics opacity table (AOT) currently used in our hydrocodes, the FPOT of deuterium from our QMD calculations has shown a significant increase in opacity for strongly coupled and degenerate plasma conditions by a factor of 3-100 in the ICF-relevant photon-energy range. As conditions approach those of classical plasma, the opacity from the FPOT converges to the corresponding values of the AOT. By implementing the FPOT of deuterium and the DT mixture into our hydrocodes, we have performed radiation-hydrodynamics simulations for low-adiabat cryogenic DT implosions on the OMEGA laser and for direct-drive-ignition designs for the National Ignition Facility. The simulation results using the FPOT show that the target performance (in terms of neutron yield and energy gain) could vary from ∼10% up to a factor of ∼2 depending on the adiabat of the imploding DT capsule; the lower the adiabat, the more variation is seen in the prediction of target performance when compared to the AOT modeling.

Magnetized Target Fusion Driven by Plasma Liners

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Eskridge, Richard; Smith, James; Lee, Michael; Richeson, Jeff; Schmidt, George; Knapp, Charles E.; Kirkpatrick, Ronald C.; Turchi, Peter J.; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

Magnetized target fusion (MTF) attempts to combine the favorable attributes of magnetic confinement fusion (MCF) for energy confinement with the attributes of inertial confinement fusion (ICF) for efficient compression heating and wall-free containment of the fusing plasma. It uses a material liner to compress and contain a magnetized plasma. For practical applications, standoff drivers to deliver the imploding momentum flux to the target plasma remotely are required. Spherically converging plasma jets have been proposed as standoff drivers for this purpose. The concept involves the dynamic formation of a spherical plasma liner by the merging of plasma jets, and the use of the liner so formed to compress a spheromak or a field reversed configuration (FRC). For the successful implementation of the scheme, plasma jets of the requisite momentum flux density need to be produced. Their transport over sufficiently large distances (a few meters) needs to be assured. When they collide and merge into a liner, relative differences in velocity, density and temperature of the jets could give rise to instabilities in the development of the liner. Variation in the jet properties must be controlled to ensure that the growth rate of the instabilities are not significant over the time scale of the liner formation before engaging with the target plasma. On impact with the target plasma, some plasma interpenetration might occur between the liner and the target. The operating parameter space needs to be identified to ensure that a reasonably robust and conducting contact surface is formed between the liner and the target. A mismatch in the "impedance" between the liner and the target plasma could give rise to undesirable shock heating of the liner leading to increased entropy (thermal losses) in the liner. Any irregularities in the liner will accentuate the Rayleigh-Taylor instabilities during the compression of the target plasma by the liner.

Kinetic Effects in Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Kagan, Grigory

2014-10-01

Sharp background gradients, inevitably introduced during ICF implosion, are likely responsible for the discrepancy between the predictions of the standard single-fluid rad-hydro codes and the experimental observations. On the one hand, these gradients drive the inter-ion-species transport, so the fuel composition no longer remains constant, unlike what the single-fluid codes assume. On the other hand, once the background scale is comparable to the mean free path, a fluid description becomes invalid. This point takes on special significance in plasmas, where the particle's mean free path scales with the square of this particle's energy. The distribution function of energetic ions may therefore be far from Maxwellian, even if thermal ions are nearly equilibrated. Ironically, it is these energetic, or tail, ions that are supposed to fuse at the onset of ignition. A combination of studies has been conducted to clarify the role of such kinetic effects on ICF performance. First, transport formalism applicable to multi-component plasmas has been developed. In particular, a novel ``electro-diffusion'' mechanism of the ion species separation has been shown to exist. Equally important, in drastic contrast to the classical case of the neutral gas mixture, thermo-diffusion is predicted to be comparable to, or even much larger than, baro-diffusion. By employing the effective potential theory this formalism has then been generalized to the case of a moderately coupled plasma with multiple ion species, making it applicable to the problem of mix at the shell/fuel interface in ICF implosion. Second, distribution function for the energetic ions has been found from first principles and the fusion reactivity reduction has been calculated for hot-spot relevant conditions. A technique for approximate evaluation of the distribution function has been identified. This finding suggests a path to effectively introducing the tail modification effects into mainline rad-hydro codes, while being in good agreement with the first principle based solution. This work was partially supported by the Laboratory Directed Research and Development (LDRD) program of LANL.

Simulations of Radiation-Driven Shock Wave Experiments

NASA Astrophysics Data System (ADS)

Dukart, R. J.; Asay, J. R.; Porter, J. L.; Matzen, M. K.

1997-07-01

For inertial confinement fusion (I.C.F.) target design, we need to understand material properties between 1- and 150-Mbar pressure. In this presentation we will show that we can use radiatively-driven ablation to generate high pressures in a wide variety of materials. PBFA-Z is being developed to generate centimeter scale hohlraums with temperatures from 80 to 150 eV. 1-D radiation/hydrodynamic simulations using these hohlraums predict the generation 1- to 15-Mbar pressures in a wide variety of materials through direct ablation. Through the use of thick ablators, we can obtain 4.5- to 25-Mbar pressures in Aluminum. This pressure regime can be extended to 40 Mbar for 200-eV hohlraums predicted for the X1, next generation, Z-pinch driver.

Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility

DOE PAGES

Izumi, N.; Meezan, N. B.; Divol, L.; ...

2016-08-12

The high fuel capsule compression required for indirect drive inertial confinement fusion (ICF) requires careful control of the X-raydrive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagation and hencethe X-raydrive symmetry especially at thefinal stage of the drive pulse. In order to quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Finally, we discuss details of the experiment andmore » the technique of spectrally selectivex-ray imaging.« less

FY17 LLNL Omega Experimental Programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heeter, R. F.; Albert, F.; Ali, S. J.

The Capseed campaign goal is to measure shock front velocity non-uniformities in Inertial Confinement Fusion (ICF) ablator materials and quantify the level of non-uniformity caused by intrinsic effects. This is done using the Omega High Resolution Velocimeter (OHRV) to obtain velocity maps of the optically reflecting shock front following release of the ablator material into either PMMA for the warm experiments or cryogenic deuterium for the cryo experiments. For the three half-days in FY17 the focus was twofold: complete measurements on the impact of oxygen heterogeneity and oxygen mitigation layers for glow discharge polymer (GDP), and begin measuring velocity non-uniformitiesmore » on deep release from Be, GDP, and highdensity carbon (HDC) into D2 with improved velocity sensitivity.« less

Observation of hohlraum-wall motion with spectrally selective x-ray imaging at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izumi, N.; Meezan, N. B.; Divol, L.

The high fuel capsule compression required for indirect drive inertial confinement fusion (ICF) requires careful control of the X-raydrive symmetry throughout the laser pulse. When the outer cone beams strike the hohlraum wall, the plasma ablated off the hohlraum wall expands into the hohlraum and can alter both the outer and inner cone beam propagation and hencethe X-raydrive symmetry especially at thefinal stage of the drive pulse. In order to quantitatively understand the wall motion, we developed a new experimental technique which visualizes the expansion and stagnation of the hohlraum wall plasma. Finally, we discuss details of the experiment andmore » the technique of spectrally selectivex-ray imaging.« less

Metal shell technology based upon hollow jet instability. [for inertial confinement fusion

NASA Technical Reports Server (NTRS)

Kendall, J. M.; Lee, M. C.; Wang, T. G.

1982-01-01

Spherical shells of submillimeter size are sought as ICF targets. Such shells must be dimensionally precise, smooth, of high strength, and composed of a high atomic number material. A technology for the production of shells based upon the hydrodynamic instability of an annular jet of molten metal is described. Shells in the 0.7-2.0 mm size range have been produced using tin as a test material. Specimens exhibit good sphericity, fair concentricity, and excellent finish over most of the surface. Work involving a gold-lead-antimony alloy is in progress. Droplets of this are amorphous and possess superior surface finish. The flow of tin models that of the alloy well; experiments on both metals show that the technique holds considerable promise.

Positron radiography of ignition-relevant ICF capsules

NASA Astrophysics Data System (ADS)

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.

Damage resistant optics for a mega-joule solid-state laser

NASA Astrophysics Data System (ADS)

Campbell, J. H.; Rainer, F.; Kozlowski, M. R.; Wolfe, C. R.; Thomas, I.; Milanovich, F.

1990-12-01

Research on Inertial Confinement Fusion (ICF) has progressed rapidly in the past several years. As a consequence, LLNL is developing plans to upgrade the current 120 kJ solid state (Nd3+ phosphate glass) Nova laser to a 1.5 to 2 megajoule system with the goal of achieving fusion ignition. The design of the planned Nova Upgrade is briefly discussed. Because of recent improvements in the damage resistance of optical materials it is now technically and economically feasible to build a megajoule-class solid state laser. Specifically, the damage threshold of Nd(+3)-doped phosphate laser glass, multilayer dielectric coatings, and non-linear optical crystals (e.g., KDP) have been dramatically improved. These materials now meet the fluence requirements for a 1.5 to 2 MJ Nd(+3)-glass laser operating at 1054 and 351 nm and at a pulse length of 3 ns. The recent improvements in damage thresholds are reviewed; threshold data at both 1064 and 355 nm and the measured pulse length scaling are presented.

Damage resistant optics for a megajoule solid state laser

NASA Astrophysics Data System (ADS)

Campbell, Jack H.; Rainer, Frank; Kozlowski, Mark R.; Wolfe, C. Robert; Thomas, Ian M.; Milanovich, Fred P.

1991-06-01

Research on Inertial Confinement Fusion (ICF) has progressed rapidly in the past several years. As a consequence LLNL is developing plans to upgrade the current 120 kJ solid state (Nd3-phosphate glass) Nova laser to a 1 . 5 to 2 megajoule system with the goal of achieving fusion ignition. The design of the planned Nova Upgrade is briefly discussed. Because of recent improvements in the damage resistance of optical materials it is now technically and economically feasible to build a megajoule-class solid state laser. Specifically the damage threshold of Nd3- doped phosphate laser glass muliilayer dielectric coatings and non-linear optical crystals (e. g. KDP) have been dramatically improved. These materials now meet the fluence requirements for a 1. 5-2 MJ Nd3-glass laser operating at 1054 and 351 nm and at a pulse length of 3 ns. The recent improvements in damage thresholds are reviewed threshold data at both 1064 and 355 nm and the measured pulse length scaling are presented. 1.

Laser program annual report 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendricks, C.D.; Rufer, M.L.; Murphy, P.W.

1984-06-01

In the 1983 Laser Program Annual Report we present the accomplishments and unclassified activities of the Laser Program at Lawrence Livermore National laboratory (LLNL) for the year 1983. It should be noted that the report, of necessity, is a summary, and more detailed expositions of the research can be found in the many publications and reports authored by staff members in the Laser Program. The purpose of this report is to present our work in a brief form, but with sufficient depth to provide an overview of the analytical and experimental aspects of the LLNL Inertial-Confinement Fusion (ICF) Program. Themore » format of this report is basically the same as that of previous years. Section 1 is an overview and highlights the important accomplishments and directions of the Program. Sections 2 through 7 provide the detailed information on the various major parts of the Program: Laser Systems and Operations, Target Design, Target Fabrication, Fusion Experiments, Laser Research and Development, and Energy Applications.« less

Parameter space for the collective laser coupling in the laser fusion driver based on the concept of fiber amplification network.

PubMed

Huang, Zhihua; Lin, Honghuan; Xu, Dangpeng; Li, Mingzhong; Wang, Jianjun; Deng, Ying; Zhang, Rui; Zhang, Yongliang; Tian, Xiaocheng; Wei, Xiaofeng

2013-07-15

Collective laser coupling of the fiber array in the inertial confinement fusion (ICF) laser driver based on the concept of fiber amplification network (FAN) is researched. The feasible parameter space is given for laser coupling of the fundamental, second and third harmonic waves by neglecting the influence of the frequency conversion on the beam quality under the assumption of beam quality factor conservation. Third harmonic laser coupling is preferred due to its lower output energy requirement from a single fiber amplifier. For coplanar fiber array, the energy requirement is around 0.4 J with an effective mode field diameter of around 500 μm while maintaining the fundamental mode operation which is more than one order of magnitude higher than what can be achieved with state-of-the-art technology. Novel waveguide structure needs to be developed to enlarge the fundamental mode size while mitigating the catastrophic self-focusing effect.

The National Ignition Facility modular Kirkpatrick-Baez microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pickworth, L. A., E-mail: pickworth1@llnl.gov; Ayers, J.; Bell, P.

Current two-dimensional X-ray imaging at the National Ignition Facility (NIF) uses time resolved pinhole cameras with ∼10-25 μm pinholes. This method has limitations in the smallest resolvable features that can be imaged with reasonable photon statistics for inertial confinement fusion (ICF) applications. ICF sources have a broadband self-emission spectrum that causes the pinhole images obtained, through thin foil filters, to contain a similarly broadband spectrum complicating the interpretation of structure in the source. In order to study phenomena on the scale of ∼5 μm, such as dopant mix in the ICF capsule, a narrow energy band, higher spatial resolution microscopemore » system with improved signal/noise has been developed using X-ray optics. Utilizing grazing incidence mirrors in a Kirkpatrick-Baez microscope (KBM) configuration [P. Kirkpatrick and A. V. Baez, J. Opt. Soc. Am. 38, 766–774 (1948)], an X-ray microscope has been designed and fielded on NIF with four imaging channels. The KBM has ∼12 × magnification, <8 μm resolution, and higher throughput in comparison to similar pinhole systems. The first KBM mirrors are coated with a multilayer mirror to allow a “narrow band” energy response at 10.2 keV with ΔE ∼ 3 keV. By adjusting the mirror coating only, the energy response can be matched to the future experimental requirements. Several mirror packs have been commissioned and are interchangeable in the diagnostic snout.« less

A 2D and 3D Code Comparison of Turbulent Mixing in Spherical Implosions

NASA Astrophysics Data System (ADS)

Flaig, Markus; Thornber, Ben; Grieves, Brian; Youngs, David; Williams, Robin; Clark, Dan; Weber, Chris

2016-10-01

Turbulent mixing due to Richtmyer-Meshkov and Rayleigh-Taylor instabilities has proven to be a major obstacle on the way to achieving ignition in inertial confinement fusion (ICF) implosions. Numerical simulations are an important tool for understanding the mixing process, however, the results of such simulations depend on the choice of grid geometry and the numerical scheme used. In order to clarify this issue, we compare the simulation codes FLASH, TURMOIL, HYDRA, MIRANDA and FLAMENCO for the problem of the growth of single- and multi-mode perturbations on the inner interface of a dense imploding shell. We consider two setups: A single-shock setup with a convergence ratio of 4, as well as a higher convergence multi-shock setup that mimics a typical NIF mixcap experiment. We employ both singlemode and ICF-like broadband perturbations. We find good agreement between all codes concerning the evolution of the mix layer width, however, the are differences in the small scale mixing. We also develop a Bell-Plesset model that is able to predict the mix layer width and find excellent agreement with the simulation results. This work was supported by resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government.

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swadling, G. F.; Ross, J. S.; Datte, P.

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimatedmore » to be ∼8 J cm{sup −2}. This is significantly above the expected threshold for the onset of “blanking” effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate “blanking.” Estimates suggest that an areal density of 10{sup 19} cm{sup −2} Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.« less

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swadling, G. F.; Ross, J. S.; Datte, P.

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Labs (LLNL). This diagnostic is designed to make measurements of hohlraum plasma parameters, such as the electron temperature and density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated tomore » be ~ 8 J cm -2. This is then significantly above the expected threshold for the onset of “blanking” effects. A novel Xenon Plasma X-ray Shield (XPXS) has been proposed to protect the blast shield from x-rays and mitigate “blanking”. Finally, these estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% the soft x-ray flux. Two potential designs for this shield are presented.« less

Planarization of Isolated Defects on ICF Target Capsule Surfaces by Pulsed Laser Ablation

DOE PAGES

Alfonso, Noel; Carlson, Lane C.; Bunn, Thomas L.

2016-08-09

Demanding surface quality requirements for inertial confinement fusion (ICF) capsules motivated the development of a pulsed laser ablation method to reduce or eliminate undesirable surface defects. The pulsed laser ablation technique takes advantage of a full surface (4π) capsule manipulation system working in combination with an optical profiling (confocal) microscope. Based on the defect topography, the material removal rate, the laser pulse energy and its beam profile, a customized laser raster pattern is derived to remove the defect. The pattern is a table of coordinates and number of pulses that dictate how the defect will be vaporized until its heightmore » is level with the capsule surface. This paper explains how the raster patterns are optimized to minimize surface roughness and how surface roughness after laser ablation is simulated. The simulated surfaces are compared with actual ablated surfaces. Large defects are reduced to a size regime where a tumble finishing process produces very high quality surfaces devoid of high mode defects. The combined polishing processes of laser ablation and tumble finishing have become routine fabrication steps for National Ignition Facility capsule production.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caillaud, T.; Landoas, O.; Briat, M.

Inertial confinement fusion (ICF) requires a high resolution ({approx}10 {mu}m) neutron imaging system to observe deuterium and tritium (DT) core implosion asymmetries. A new large (150 mm entrance diameter: scaled for Laser MegaJoule [P. A. Holstein, F. Chaland, C. Charpin, J. M. Dufour, H. Dumont, J. Giorla, L. Hallo, S. Laffite, G. Malinie, Y. Saillard, G. Schurtz, M. Vandenboomgaerde, and F. Wagon, Laser and Particle Beams 17, 403 (1999)]) neutron imaging detector has been developed for such ICF experiments. The detector has been fully characterized using a linear accelerator and a {sup 60}Co {gamma}-ray source. A penumbral aperture was usedmore » to observe DT-gas-filled target implosions performed on the OMEGA laser facility. [T. R. Boehly, D. L. Brown, R. S. Craxton, R. L. Keck, J. P. Knauer, J. H. Kelly, T. J. Kessler, S. A. Kumpan, S. J. Loucks, S. A. Letzring, F. J. Marshall, R. L. McCrory, S. F. B. Morse, W. Seka, J. M. Soures, and C. P. Verdon, Opt. Commun. 133, 495 (1997)] Neutron core images of 14 MeV with a resolution of 15 {mu}m were obtained and are compared to x-ray images of comparable resolution.« less

Impact of flows on ion temperatures inferred from neutron spectra in asymmetrically driven OMEGA DT implosions

NASA Astrophysics Data System (ADS)

Gatu Johnson, M.; Frenje, J.; Lahmann, B.; Seguin, F.; Petrasso, R.; Appelbe, B.; Chittenden, J.; Walsh, C.; Delettrez, J.; Igumenshchev, I.; Knauer, J. P.; Glebov, V. Yu.; Forrest, C.; Grimble, W.; Marshall, F.; Michel, T.; Stoeckl, C.; Haines, B. M.; Zylstra, A. B.

2017-10-01

Ion temperatures (Tion) in Inertial Confinement Fusion (ICF) experiments have traditionally been inferred from the broadening of primary neutron spectra. Directional motion (flow) of the fuel at burn, expected to arise due to asymmetries imposed by e.g. engineering features or drive non-uniformity, also impacts broadening and may lead to artificially inflated ``Tion'' values. Flow due to low-mode asymmetries is expected to give rise to line-of-sight variations in measured Tion, as observed in OMEGA cryogenic DT implosions but not in similar experiments at the NIF. In this presentation, we report on OMEGA experiments with intentional drive asymmetry designed for testing the ability to accurately predict and measure line-of-sight differences in apparent Tion due to low-mode asymmetry-seeded flows. The measurements are contrasted to CHIMERA, RAGE and ASTER simulations, providing insight into implosion dynamics and the relative importance of laser drive non-uniformity, stalk and offset as sources of asymmetry. The results highlight the complexity of hot-spot dynamics, which is a problem that must be mastered to achieve ICF ignition. This work was supported in part by the U.S. DOE, NLUF and LLE.

Cryogenic THD and DT layer implosions with high density carbon ablators in near-vacuum hohlraums

DOE PAGES

Meezan, N. B.; Berzak Hopkins, L. F.; Le Pape, S.; ...

2015-06-02

High Density Carbon (HDC 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 [E. I. Moses et al., Phys. Plasmas 16, 041006 (2009)] culminated in a 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 THD layered capsule demonstrated an ablator implosion velocity of 385 km/s with a slightlymore » 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 x 10¹⁵ neutrons, 40% of the 1D simulated yield.« less

Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

NASA Astrophysics Data System (ADS)

Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

2013-10-01

Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

DOE PAGES

Swadling, G. F.; Ross, J. S.; Datte, P.; ...

2016-07-21

An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Labs (LLNL). This diagnostic is designed to make measurements of hohlraum plasma parameters, such as the electron temperature and density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated tomore » be ~ 8 J cm -2. This is then significantly above the expected threshold for the onset of “blanking” effects. A novel Xenon Plasma X-ray Shield (XPXS) has been proposed to protect the blast shield from x-rays and mitigate “blanking”. Finally, these estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% the soft x-ray flux. Two potential designs for this shield are presented.« less

Ignition threshold for non-Maxwellian plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hay, Michael J., E-mail: hay@princeton.edu; Fisch, Nathaniel J.; Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543

2015-11-15

An optically thin p-{sup 11}B plasma loses more energy to bremsstrahlung than it gains from fusion reactions, unless the ion temperature can be elevated above the electron temperature. In thermal plasmas, the temperature differences required are possible in small Coulomb logarithm regimes, characterized by high density and low temperature. Ignition could be reached more easily if the fusion reactivity can be improved with nonthermal ion distributions. To establish an upper bound for the potential utility of a nonthermal distribution, we consider a monoenergetic beam with particle energy selected to maximize the beam-thermal reactivity. Comparing deuterium-tritium (DT) and p-{sup 11}B, themore » minimum Lawson criteria and minimum ρR required for inertial confinement fusion (ICF) volume ignition are calculated with and without the nonthermal feature. It turns out that channeling fusion alpha energy to maintain such a beam facilitates ignition at lower densities and ρR, improves reactivity at constant pressure, and could be used to remove helium ash. On the other hand, the reactivity gains that could be realized in DT plasmas are significant, the excess electron density in p-{sup 11}B plasmas increases the recirculated power cost to maintain a nonthermal feature and thereby constrains its utility to ash removal.« less

Sensitivity of low-energy incomplete fusion to various entrance-channel parameters

NASA Astrophysics Data System (ADS)

Kumar, Harish; Tali, Suhail A.; Afzal Ansari, M.; Singh, D.; Ali, Rahbar; Kumar, Kamal; Sathik, N. P. M.; Ali, Asif; Parashari, Siddharth; Dubey, R.; Bala, Indu; Kumar, R.; Singh, R. P.; Muralithar, S.

2018-03-01

The disentangling of incomplete fusion dependence on various entrance channel parameters has been made from the forward recoil range distribution measurement for the 12C+175Lu system at ≈ 88 MeV energy. It gives the direct measure of full and/or partial linear momentum transfer from the projectile to the target nucleus. The comparison of observed recoil ranges with theoretical ranges calculated using the code SRIM infers the production of evaporation residues via complete and/or incomplete fusion process. Present results show that incomplete fusion process contributes significantly in the production of α xn and 2α xn emission channels. The deduced incomplete fusion probability (F_{ICF}) is compared with that obtained for systems available in the literature. An interesting behavior of F_{ICF} with ZP ZT is observed in the reinvestigation of incomplete fusion dependency with the Coulomb factor (ZPZT), contrary to the recent observations. The present results based on (ZPZT) are found in good agreement with recent observations of our group. A larger F_{ICF} value for 12C induced reactions is found than that for 13C, although both have the same ZPZT. A nonsystematic behavior of the incomplete fusion process with the target deformation parameter (β2) is observed, which is further correlated with a new parameter (ZP ZT . β2). The projectile α -Q-value is found to explain more clearly the discrepancy observed in incomplete fusion dependency with parameters ( ZPZT) and (ZP ZT . β2). It may be pointed out that any single entrance channel parameter (mass-asymmetry or (ZPZT) or β2 or projectile α-Q-value) may not be able to explain completely the incomplete fusion process.

Description of the NIF Laser

DOE PAGES

Spaeth, M. L.; Manes, K. R.; Kalantar, D. H.; ...

2017-03-23

The possibility of imploding small capsules to produce mini-fusion explosions was explored soon after the first thermonuclear explosions in the early 1950s. Various technologies have been pursued to achieve the focused power and energy required for laboratory-scale fusion. Each technology has its own challenges. For example, electron and ion beams can deliver the large amounts of energy but must contend with Coulomb repulsion forces that make focusing these beams a daunting challenge. The demonstration of the first laser in 1960 provided a new option. Energy from laser beams can be focused and deposited within a small volume; the challenge becamemore » whether a practical laser system can be constructed that delivers the power and energy required while meeting all other demands for achieving a high-density, symmetric implosion. The National Ignition Facility (NIF) is the laser designed and built to meet the challenges for study of high-energy-density physics and inertial confinement fusion (ICF) implosions. This study describes the architecture, systems, and subsystems of NIF. Finally, it describes how they partner with each other to meet these new, complex demands and describes how laser science and technology were woven together to bring NIF into reality.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spaeth, M. L.; Manes, K. R.; Kalantar, D. H.

The possibility of imploding small capsules to produce mini-fusion explosions was explored soon after the first thermonuclear explosions in the early 1950s. Various technologies have been pursued to achieve the focused power and energy required for laboratory-scale fusion. Each technology has its own challenges. For example, electron and ion beams can deliver the large amounts of energy but must contend with Coulomb repulsion forces that make focusing these beams a daunting challenge. The demonstration of the first laser in 1960 provided a new option. Energy from laser beams can be focused and deposited within a small volume; the challenge becamemore » whether a practical laser system can be constructed that delivers the power and energy required while meeting all other demands for achieving a high-density, symmetric implosion. The National Ignition Facility (NIF) is the laser designed and built to meet the challenges for study of high-energy-density physics and inertial confinement fusion (ICF) implosions. This study describes the architecture, systems, and subsystems of NIF. Finally, it describes how they partner with each other to meet these new, complex demands and describes how laser science and technology were woven together to bring NIF into reality.« less

The Magnetic Recoil Spectrometer for time-resolved neutron measurements (MRSt) at the NIF

NASA Astrophysics Data System (ADS)

Parker, C. E.; Frenje, J. A.; Wink, C. W.; Gatu Johnson, M.; Lahmann, B.; Li, C. K.; Seguin, F. H.; Petrasso, R. D.; Hilsabeck, T. J.; Kilkenny, J. D.; Bionta, R.; Casey, D. T.; Khater, H. Y.; Forrest, C. J.; Glebov, V. Yu.; Sorce, C.; Hares, J. D.; Siegmund, O. H. W.

2017-10-01

The next-generation Magnetic Recoil Spectrometer, called MRSt, will provide time-resolved measurements of the DT-neutron spectrum. These measurements will provide critical information about the time evolution of the fuel assembly, hot-spot formation, and nuclear burn in Inertial Confinement Fusion (ICF) implosions at the National Ignition Facility (NIF). The neutron spectrum in the energy range 12-16 MeV will be measured with high accuracy ( 5%), unprecedented energy resolution ( 100 keV) and, for the first time ever, time resolution ( 20 ps). An overview of the physics motivation, conceptual design for meeting these performance requirements, and the status of the offline tests for critical components will be presented. This work was supported in part by the U.S. DOE, LLNL, and LLE.

Enhancements to the timing of the OMEGA laser system to improve illumination uniformity

NASA Astrophysics Data System (ADS)

Donaldson, W. R.; Katz, J.; Kosc, T. Z.; Kelly, J. H.; Hill, E. M.; Bahr, R. E.

2016-09-01

Two diagnostics have been developed to improve the uniformity on the OMEGA Laser System, which is used for inertial confinement fusion (ICF) research. The first diagnostic measures the phase of an optical modulator (used for the spectral dispersion technique employed on OMEGA to enhance spatial smoothing), which adds bandwidth to the optical pulse. Setting this phase precisely is required to reduce pointing errors. The second diagnostic ensures that the arrival times of all the beams are synchronized. The arrival of each of the 60 OMEGA beams is measured by placing a 1-mm diffusing sphere at target chamber center. By comparing the arrival time of each beam with respect to a reference pulse, the measured timing spread of the OMEGA Laser System is now 3.8 ps.

Advances in shock timing experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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.

Positron radiography of ignition-relevant ICF capsules

DOE PAGES

Williams, G. J.; Chen, Hui; Field, J. E.; ...

2017-12-11

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 ×10 12 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 2g/cm 2. 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. Here, we evaluate the effects of magnetic fields near themore » capsule surface using analytic estimates where it is shown that this diagnostic can tolerate line integrated field strengths of 100 T mm.« less

Positron radiography of ignition-relevant ICF capsules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, G. J.; Chen, Hui; Field, J. E.

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 ×10 12 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 2g/cm 2. 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. Here, we evaluate the effects of magnetic fields near themore » capsule surface using analytic estimates where it is shown that this diagnostic can tolerate line integrated field strengths of 100 T mm.« less

A new gated x-ray detector for the Orion laser facility

NASA Astrophysics Data System (ADS)

Clark, David D.; Aragonez, Robert; Archuleta, Thomas; Fatherley, Valerie; Hsu, Albert; Jorgenson, Justin; Mares, Danielle; Oertel, John; Oades, Kevin; Kemshall, Paul; Thomas, Phillip; Young, Trevor; Pederson, Neal

2012-10-01

Gated X-Ray Detectors (GXD) are considered the work-horse target diagnostic of the laser based inertial confinement fusion (ICF) program. Recently, Los Alamos National Laboratory (LANL) has constructed three new GXDs for the Orion laser facility at the Atomic Weapons Establishment (AWE) in the United Kingdom. What sets these three new instruments apart from what has previously been constructed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is: improvements in detector head microwave transmission lines, solid state embedded hard drive and updated control software, and lighter air box design and other incremental mechanical improvements. In this paper we will present the latest GXD design enhancements and sample calibration data taken on the Trident laser facility at Los Alamos National Laboratory using the newly constructed instruments.

Time-resolved absolute measurements by electro-optic effect of giant electromagnetic pulses due to laser-plasma interaction in nanosecond regime

PubMed Central

Consoli, F.; De Angelis, R.; Duvillaret, L.; Andreoli, P. L.; Cipriani, M.; Cristofari, G.; Di Giorgio, G.; Ingenito, F.; Verona, C.

2016-01-01

We describe the first electro-optical absolute measurements of electromagnetic pulses (EMPs) generated by laser-plasma interaction in nanosecond regime. Laser intensities are inertial-confinement-fusion (ICF) relevant and wavelength is 1054 nm. These are the first direct EMP amplitude measurements with the detector rather close and in direct view of the plasma. A maximum field of 261 kV/m was measured, two orders of magnitude higher than previous measurements by conductive probes on nanosecond regime lasers with much higher energy. The analysis of measurements and of particle-in-cell simulations indicates that signals match the emission of charged particles detected in the same experiment, and suggests that anisotropic particle emission from target, X-ray photoionization and charge implantation on surfaces directly exposed to plasma, could be important EMP contributions. Significant information achieved on EMP features and sources is crucial for future plants of laser-plasma acceleration and inertial-confinement-fusion and for the use as effective plasma diagnostics. It also opens to remarkable applications of laser-plasma interaction as intense source of RF-microwaves for studies on materials and devices, EMP-radiation-hardening and electromagnetic compatibility. The demonstrated extreme effectivity of electric-fields detection in laser-plasma context by electro-optic effect, leads to great potential for characterization of laser-plasma interaction and generated Terahertz radiation. PMID:27301704

Time-resolved absolute measurements by electro-optic effect of giant electromagnetic pulses due to laser-plasma interaction in nanosecond regime

NASA Astrophysics Data System (ADS)

Consoli, F.; de Angelis, R.; Duvillaret, L.; Andreoli, P. L.; Cipriani, M.; Cristofari, G.; di Giorgio, G.; Ingenito, F.; Verona, C.

2016-06-01

We describe the first electro-optical absolute measurements of electromagnetic pulses (EMPs) generated by laser-plasma interaction in nanosecond regime. Laser intensities are inertial-confinement-fusion (ICF) relevant and wavelength is 1054 nm. These are the first direct EMP amplitude measurements with the detector rather close and in direct view of the plasma. A maximum field of 261 kV/m was measured, two orders of magnitude higher than previous measurements by conductive probes on nanosecond regime lasers with much higher energy. The analysis of measurements and of particle-in-cell simulations indicates that signals match the emission of charged particles detected in the same experiment, and suggests that anisotropic particle emission from target, X-ray photoionization and charge implantation on surfaces directly exposed to plasma, could be important EMP contributions. Significant information achieved on EMP features and sources is crucial for future plants of laser-plasma acceleration and inertial-confinement-fusion and for the use as effective plasma diagnostics. It also opens to remarkable applications of laser-plasma interaction as intense source of RF-microwaves for studies on materials and devices, EMP-radiation-hardening and electromagnetic compatibility. The demonstrated extreme effectivity of electric-fields detection in laser-plasma context by electro-optic effect, leads to great potential for characterization of laser-plasma interaction and generated Terahertz radiation.

Generating High-Brightness Ion Beams for Inertial Confinement Fusion

NASA Astrophysics Data System (ADS)

Cuneo, M. E.

1997-11-01

The generation of high current density ion beams with applied-B ion diodes showed promise in the late-1980's as an efficient, rep-rate, focusable driver for inertial confinement fusion. These devices use several Tesla insulating magnetic fields to restrict electron motion across anode-cathode gaps of order 1-2 cm, while accelerating ions to generate ≈ 1 kA/cm^2, 5 - 15 MeV beams. These beams have been used to heat hohlraums to about 65 eV. However, meeting the ICF driver requirements for low-divergence and high-brightness lithium ion beams has been more technically challenging than initially thought. Experimental and theoretical work over the last 5 years shows that high-brightness beams meeting the requirements for inertial confinement fusion are possible. The production of these beams requires the simultaneous integration of at least four conditions: 1) rigorous vacuum cleaning techniques for control of undesired anode, cathode, ion source and limiter plasma formation from electrode contaminants to control impurity ions and impedance collapse; 2) carefully tailored insulating magnetic field geometry for uniform beam generation; 3) high magnetic fields (V_crit/V > 2) and other techniques to control the electron sheath and the onset of a high divergence electromagnetic instability that couples strongly to the ion beam; and 4) an active, pre-formed, uniform lithium plasma for low source divergence which is compatible with the above electron-sheath control techniques. These four conditions have never been simultaneously present in any lithium beam experiment, but simulations and experimental tests of individual conditions have been done. The integration of these conditions is a goal of the present ion beam generation program at Sandia. This talk will focus on the vacuum cleaning techniques for ion diodes and pulsed power devices in general, including experimental results obtained on the SABRE and PBFA-II accelerators over the last 3 years. The current status of integration of the other key physics and technologies required to demonstrate high-brightness ion beams will also be presented.

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

DOE PAGES

Taitano, William T.; Simakov, Andrei N.; Chacon, Luis; ...

2018-04-09

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 ICFmore » capsule implosions with the fuel comprising various hydrodynamically equivalent mixtures of deuterium (D) and helium-3 (3He), as in the original. We employ the same computational setup as in O. Larroche, 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 fuel-ablator interface, they cannot capture the effects of ion viscosity on the capsule compression, or effects associated with the interface, which are expected to be important. As a result, studies of such effects are left for future work.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taitano, William T.; Simakov, Andrei N.; Chacon, Luis

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 ICFmore » capsule implosions with the fuel comprising various hydrodynamically equivalent mixtures of deuterium (D) and helium-3 (3He), as in the original. We employ the same computational setup as in O. Larroche, 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 fuel-ablator interface, they cannot capture the effects of ion viscosity on the capsule compression, or effects associated with the interface, which are expected to be important. As a result, studies of such effects are left for future work.« less

Inertial Confinement Fusion Annual Report 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kauffman, Robert L.

The ICF Program has undergone a significant change in 1999 with the decommissioning of the Nova laser and the transfer of much of the experimental program to the OMEGA laser at the University of Rochester. The Nova laser ended operations with the final experiment conducted on May 27, 1999. This marked the end to one of DOE's most successful experimental facilities. Since its commissioning in 1985, Nova performed 13,424 experiments supporting ICF, Defense Sciences, high-power laser research, and basic science research. At the time of its commissioning, Nova was the world's most powerful laser. Its early experiments demonstrated that 3ωmore » light could produce high-drive, low-preheat environment required for indirect-drive ICE. In the early 1990s, the technical program on Nova for indirect drive ignition was defined by the Nova technical contract established by National Academy Review of ICF in 1990. Successful completion of this research program contributed significantly to the recommendation by the ICF Advisory Committee in 1995 to proceed with the construction of the National Ignition Facility? Nova experiments also demonstrated the utility of high-powered lasers for studying the physics of interest to Defense Sciences. Now, high-powered lasers along with pulsed-power machines are the principal facilities for studying high energy density science in DOE's Stockpile Stewardship Program (SSP). In 1997, one beam of Nova was converted to a short pulsed beam producing a petawatt of power in subpicosecond pulses. The petawatt beam was used for pioneering research in short-pulse laser-matter interactions relevant to fast ignitor ICF and short pulsed x-ray, electron, and particle production for use as probes. Nova is being disassembled and the space is being used to support NIF construction. Nova components are being distributed to a number of other laser laboratories around the world for reuse as determined by DOE. This report summarizes the research performed by the ICF Program in FY1999. The report is divided into five sections corresponding to the major areas of program activities. These are sections on (1) ignition target physics experiments theory and modeling, (2) high energy density experimental science, (3) target development, fabrication, and handling, (4) NIF laser development, and (5) optics technology development.« less

Incomplete fusion analysis of the 7Li-induced reaction on 93Nb within 3-6.5 MeV/nucleon

NASA Astrophysics Data System (ADS)

Kumar, Deepak; Maiti, Moumita

2017-10-01

Background: It is understood from the recent experimental studies that prompt/resonant breakup, and transfer followed by breakup in the weakly bound Li,76-induced reactions play a significant role in the complete-incomplete fusion (CF-ICF), suppression/enhancement in the fusion cross section around the Coulomb barrier. Purpose: Investigation of ICF over CF by measuring cross sections of the populated residues, produced via different channels in the 7Li-induced reaction on a natNb target within the 3-6.5 MeV/nucleon energy region. Method: The 7Li beam was allowed to hit the self-supporting 93Nb targets, backed by the aluminium (Al) foil alternately, within 3-6.5 MeV/nucleon energy. Populated residues were identified by offline γ -ray spectrometry. Measured excitation functions of different channels were compared with different equilibrium and pre-equilibrium models. Result: The enhancement in cross sections in the proton (˜20 -30 MeV) and α -emitting channels, which may be ascribed to ICF, was observed in the measured energy range when compared to the Hauser-Feshbach and exciton model calculations using empire, which satisfactorily reproduces the neutron channels, compared to the Weisskopf-Ewing model and hybrid Monte Carlo calculations. The increment of the incomplete fusion fraction was observed with rising projectile energy. Conclusion: Contrary to the alice14, experimental results are well reproduced by the empire throughout the measured energy range. The signature of ICF over CF indicates that the breakup/transfer processes are involved in the weakly bound 7Li-induced reaction on 93Nb slightly above the Coulomb barrier.

The neutron imaging diagnostic at NIF (invited).

PubMed

Merrill, F E; Bower, D; Buckles, R; Clark, D D; Danly, C R; Drury, O B; Dzenitis, J M; Fatherley, V E; Fittinghoff, D N; Gallegos, R; Grim, G P; Guler, N; Loomis, E N; Lutz, S; Malone, R M; Martinson, D D; Mares, D; Morley, D J; Morgan, G L; Oertel, J A; Tregillis, I L; Volegov, P L; Weiss, P B; Wilde, C H; Wilson, D C

2012-10-01

A neutron imaging diagnostic has recently been commissioned at the National Ignition Facility (NIF). This new system is an important diagnostic tool for inertial fusion studies at the NIF for measuring the size and shape of the burning DT plasma during the ignition stage of Inertial Confinement Fusion (ICF) implosions. The imaging technique utilizes a pinhole neutron aperture, placed between the neutron source and a neutron detector. The detection system measures the two dimensional distribution of neutrons passing through the pinhole. This diagnostic has been designed to collect two images at two times. The long flight path for this diagnostic, 28 m, results in a chromatic separation of the neutrons, allowing the independently timed images to measure the source distribution for two neutron energies. Typically the first image measures the distribution of the 14 MeV neutrons and the second image of the 6-12 MeV neutrons. The combination of these two images has provided data on the size and shape of the burning plasma within the compressed capsule, as well as a measure of the quantity and spatial distribution of the cold fuel surrounding this core.

Gas-filled Rugby hohlraum energetics and implosions experiments on OMEGA

NASA Astrophysics Data System (ADS)

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).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rojas-Herrera, J., E-mail: jimmy06@mit.edu; Rinderknecht, H. G.; Zylstra, A. B.

The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray fluences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-K{sub α} and K{sub β} x-rays. The CR-39 detectors were then exposed to 1–5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those notmore » exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.« less

Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications

DOE PAGES

Rosenberg, M. J.; Séguin, F. H.; Waugh, C. J.; ...

2014-04-14

CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ~0.5–8 MeV protons. When the fluence of incident particles becomes too high, the overlap of particle tracks leads to under-counting at typical processing conditions (5h etch in 6N NaOH at 80°C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7–4.3-MeV protons and established that for 2.4-MeV protons, relevant for detectionmore » of DD protons, the maximum fluence that can be detected using normal processing techniques is ≲3 ×10 6 cm -2. A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ~50, increasing the operating yield upper limit by a comparable amount.« less

Ion species stratification within strong shocks in two-ion plasmas

DOE PAGES

Keenan, Brett D.; Simakov, Andrei N.; Taitano, William T.; ...

2018-03-01

We report strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan et al., Phys. Rev. E 96, 053203 (2017)] answered in detail a number of outstanding questions concerning the kinetic structure of steady-state, planar plasma shocks, e.g., the shock width scaling by the Mach number, M. However, it did not discuss shock-driven ion-species stratification (e.g., relative concentration modification and temperature separation). These are important effects since many recent ICF experiments have evaded explanation by standard, single-fluid, radiation-hydrodynamic (rad-hydro) numerical simulations, and shock-driven fuel stratification likelymore » contributes to this discrepancy. Employing the state-of-the-art Vlasov-Fokker-Planck code, iFP, along with multi-ion hydro simulations and semi-analytics, we quantify the ion stratification by planar shocks with the arbitrary Mach number and the relative species concentration for two-ion plasmas in terms of ion mass and charge ratios. In particular, for strong shocks, we find that the structure of the ion temperature separation has a nearly universal character across ion mass and charge ratios. Lastly, we find that the shock fronts are enriched with the lighter ion species and the enrichment scales as M 4 for M»1.« less

Ion species stratification within strong shocks in two-ion plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keenan, Brett D.; Simakov, Andrei N.; Taitano, William T.

We report strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan et al., Phys. Rev. E 96, 053203 (2017)] answered in detail a number of outstanding questions concerning the kinetic structure of steady-state, planar plasma shocks, e.g., the shock width scaling by the Mach number, M. However, it did not discuss shock-driven ion-species stratification (e.g., relative concentration modification and temperature separation). These are important effects since many recent ICF experiments have evaded explanation by standard, single-fluid, radiation-hydrodynamic (rad-hydro) numerical simulations, and shock-driven fuel stratification likelymore » contributes to this discrepancy. Employing the state-of-the-art Vlasov-Fokker-Planck code, iFP, along with multi-ion hydro simulations and semi-analytics, we quantify the ion stratification by planar shocks with the arbitrary Mach number and the relative species concentration for two-ion plasmas in terms of ion mass and charge ratios. In particular, for strong shocks, we find that the structure of the ion temperature separation has a nearly universal character across ion mass and charge ratios. Lastly, we find that the shock fronts are enriched with the lighter ion species and the enrichment scales as M 4 for M»1.« less

Ion species stratification within strong shocks in two-ion plasmas

NASA Astrophysics Data System (ADS)

Keenan, Brett D.; Simakov, Andrei N.; Taitano, William T.; Chacón, Luis

2018-03-01

Strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan et al., Phys. Rev. E 96, 053203 (2017)] answered in detail a number of outstanding questions concerning the kinetic structure of steady-state, planar plasma shocks, e.g., the shock width scaling by the Mach number, M. However, it did not discuss shock-driven ion-species stratification (e.g., relative concentration modification and temperature separation). These are important effects since many recent ICF experiments have evaded explanation by standard, single-fluid, radiation-hydrodynamic (rad-hydro) numerical simulations, and shock-driven fuel stratification likely contributes to this discrepancy. Employing the state-of-the-art Vlasov-Fokker-Planck code, iFP, along with multi-ion hydro simulations and semi-analytics, we quantify the ion stratification by planar shocks with the arbitrary Mach number and the relative species concentration for two-ion plasmas in terms of ion mass and charge ratios. In particular, for strong shocks, we find that the structure of the ion temperature separation has a nearly universal character across ion mass and charge ratios. Additionally, we find that the shock fronts are enriched with the lighter ion species and the enrichment scales as M4 for M ≫ 1.

Stopping and Coulomb explosion of energetic carbon clusters in a plasma irradiated by an intense laser field

NASA Astrophysics Data System (ADS)

Wang, Guiqiu; Wang, Younian

2015-09-01

The interaction of a charged particle beam with a plasma is a very important subject of relevance for many fields of physics, such as inertial confinement fusion (ICF) driven by ion or electron beams, high energy density physics, and related astrophysical problems. Recently, a promising ICF scheme has been proposed, in which the plasma target is irradiated simultaneously by intense laser and ion beams. For molecular ion or cluster, slowing down process will company the Coulomb explosion phenomenon. In this paper, we present a study of the effects of intense radiation field (RF) on the interaction of energetic carbon clusters in a plasma. The emphasis is laid on the dynamic polarization and correlation effects of the constituent ions within the cluster in order to disclose the role of the vicinage effects on the Coulomb explosion and energy deposition of the clusters in plasma. On the other hand, affecting of a strong laser field on the cluster propagating in plasma is considered, the influence of a large range of laser parameters and plasma parameters on the Coulomb explosion and stopping power are discussed. This work is supported by the National Natural Science Foundation of China (11375034), and the Fundamental Research Funds for the Central Universities of China (3132015144, 3132014337).

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meezan, N. B., E-mail: meezan1@llnl.gov; Hopkins, L. F. Berzak; Pape, S. Le

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.more » 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.« less

Simulations and model of the nonlinear Richtmyer–Meshkov instability

DOE PAGES

Dimonte, Guy; Ramaprabhu, P.

2010-01-21

The nonlinear evolution of the Richtmyer-Meshkov (RM) instability is investigated using numerical simulations with the FLASH code in two-dimensions (2D). The purpose of the simulations is to develop an empiricial nonlinear model of the RM instability that is applicable to inertial confinement fusion (ICF) and ejecta formation, namely, at large Atwood number A and scaled initial amplitude kh o (k ≡ wavenumber) of the perturbation. The FLASH code is first validated with a variety of RM experiments that evolve well into the nonlinear regime. They reveal that bubbles stagnate when they grow by an increment of 2/k and that spikesmore » accelerate for A > 0.5 due to higher harmonics that focus them. These results are then compared with a variety of nonlinear models that are based on potential flow. We find that the models agree with simulations for moderate values of A < 0.9 and kh o< 1, but not for the larger values that characterize ICF and ejecta formation. We thus develop a new nonlinear empirical model that captures the simulation results consistent with potential flow for a broader range of A and kh o. Our hope is that such empirical models concisely capture the RM simulations and inspire more rigorous solutions.« less

Fast-Ion Spectrometry of ICF Implosions and Laser-Foil Experiments at the Omega and MTW Laser Facilities

NASA Astrophysics Data System (ADS)

Sinenian, Nareg

Fast ions generated from laser-plasma interactions (LPI) have been used to study inertial confinement fusion (ICF) implosions and laser-foil interactions. LPI, which vary in nature depending on the wavelength and intensity of the driver, generate hot electrons with temperatures ranging from tens to thousands of kilo-electron-volts. These electrons, which accelerate the ions measured in this work, can be either detrimental or essential to implosion performance depending on the ICF scheme employed. In direct-drive hot-spot ignition, hot electrons can preheat the fuel and raise the adiabat, potentially degrading compression in the implosion. The amount of preheat depends on the hot-electron source characteristics and the time duration over which electrons can deposit energy into the fuel. This time duration is prescribed by the evolution of a sheath that surrounds the implosion and traps electrons. Fast-ion measurements have been used to develop a circuit model that describes the time decay of the sheath voltage for typical OMEGA implosions. In the context of electron fast ignition, the produced fast ions are considered a loss channel that has been characterized for the first time. These ions have also been used as a diagnostic tool to infer the temperature of the hot electrons in fast-ignition experiments. It has also been shown that the hot-electron temperature scales with laser intensity as expected, but is enhanced by a factor of 2-3. This enhancement is possibly due to relativistic effects and leads to poor implosion performance. Finally, fast-ion generation by ultra-intense lasers has also been studied using planar targets. The mean and maximum energies of protons and heavy ions has been measured, and it has been shown that a two-temperature hot-electron distribution affects the energies of heavy ions and protons. This work is important for advanced fusion concepts that utilize ion beams and also has applications in medicine. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs@mit.edu)

An overview on incomplete fusion reaction dynamics at energy range ∼ 3-8 MeV/A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Rahbar, E-mail: rahbarali1@rediffmail.com; Singh, D.; Ansari, M. Afzal

2014-08-14

The information of ICF reaction has been obtained from the measurement of excitation function (EF) of ERs populated in the interaction of {sup 20}Ne and {sup 16}O on {sup 55}Mn, {sup 159}Tb and {sup 156}Gd targets. Sizable enhancement in the measured cross-sections has been observed in α-emitting channels over theoretical predictions, which has been attributed to ICF of the projectile. In order to confirm the findings of the measurements and analysis of EFs, the forward recoil range distributions of ERs populated in {sup 20}Ne+{sup 159}Tb (E ∼165MeV) and {sup 16}O+{sup 156}Gd (E ∼ 72, 82 and 93MeV) systems, have beenmore » measured. It has been observed that peaks appearing at different cumulative thicknesses in the stopping medium are related with different degree of linear momentum transfer from projectile to target nucleus by adopting the break-up fusion model consideration. In order to deduce the angular momentum involved in various CF and / or ICF reaction products, spin distribution and side-feeding intensity profiles of radio-nuclides populated via CF and ICF channels in {sup 16}O+{sup 160}Gd system at energy, E ∼ 5.6 MeV/A, have been studied. Spin distribution of ICF products are found to be distinctly different than that observed from CF products.« less

Research in pulsed power plasma physics

NASA Astrophysics Data System (ADS)

Hinshelwood, David; Rose, David

1993-11-01

The research was conducted in support of light-ion-driven inertial confinement fusion (ICF) for the Department of Energy (DOE), and nuclear weapon effects simulation (NWES) for the Defense Nuclear Agency (DNA). Accomplishments related to ion beams include: development of a practical backup approach to ion beam transport; the first studies of ion-beam interaction with a neutral gas; initial investigations of a promising industrial application of ion beam technology; and detailed theoretical evaluation of several different ion beam transport schemes. Major accomplishments relating to opening switches include: the first direct measurement of the electron density in an opening switch; detailed studies of switch conduction-time scaling; evaluation of several different switch plasma sources; and extensive studies of switch performance into diode loads, leading to the development of a new (and now generally accepted) model of switch behavior.

A nonlocal electron conduction model for multidimensional radiation hydrodynamics codes

NASA Astrophysics Data System (ADS)

Schurtz, G. P.; Nicolaï, Ph. D.; Busquet, M.

2000-10-01

Numerical simulation of laser driven Inertial Confinement Fusion (ICF) related experiments require the use of large multidimensional hydro codes. Though these codes include detailed physics for numerous phenomena, they deal poorly with electron conduction, which is the leading energy transport mechanism of these systems. Electron heat flow is known, since the work of Luciani, Mora, and Virmont (LMV) [Phys. Rev. Lett. 51, 1664 (1983)], to be a nonlocal process, which the local Spitzer-Harm theory, even flux limited, is unable to account for. The present work aims at extending the original formula of LMV to two or three dimensions of space. This multidimensional extension leads to an equivalent transport equation suitable for easy implementation in a two-dimensional radiation-hydrodynamic code. Simulations are presented and compared to Fokker-Planck simulations in one and two dimensions of space.

Neutronics Evaluation of Lithium-Based Ternary Alloys in IFE Blankets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jolodosky, A.; Fratoni, M.

2014-11-20

Pre-conceptual fusion blanket designs require research and development to reflect important proposed changes in the design of essential systems, and the new challenges they impose on related fuel cycle systems. One attractive feature of using liquid lithium as the breeder and coolant is that it has very high tritium solubility and results in very low levels of tritium permeation throughout the facility infrastructure. However, lithium metal vigorously reacts with air and water and presents plant safety concerns. If the chemical reactivity of lithium could be overcome, the result would have a profound impact on fusion energy and associated safety basis.more » The overriding goal of this project is to develop a lithium-based alloy that maintains beneficial properties of lithium (e.g. high tritium breeding and solubility) while reducing overall flammability concerns. To minimize the number of alloy combinations that must be explored, only those alloys that meet certain nuclear performance metrics will be considered for subsequent thermodynamic study. The specific scope of this study is to evaluate the neutronics performance of lithium-based alloys in the blanket of an inertial confinement fusion (ICF) engine. The results of this study will inform the development of lithium alloys that would guarantee acceptable neutronics performance while mitigating the chemical reactivity issues of pure lithium.« less

7Li-induced reaction on natMo: A study of complete versus incomplete fusion

NASA Astrophysics Data System (ADS)

Kumar, Deepak; Maiti, Moumita; Lahiri, Susanta

2017-07-01

Background: Several investigations on the complete-incomplete fusion (CF-ICF) dynamics of α -cluster well-bound nuclei have been contemplated above the Coulomb barrier (˜4 -7 MeV/nucleon) in recent years. It is therefore expected to observe significant ICF over CF in the reactions induced by a weakly bound α -cluster nucleus at slightly above the barrier. Purpose: Study of the CF-ICF dynamics by measuring the populated residues in the weakly bound 7Li+natMo system at energies slightly above the Coulomb barrier to well above it. Method: In order to investigate CF-ICF in the loosely bound system, 7Li beam was bombarded on the natMo foils, separated by the aluminium (Al) catcher foils alternatively, within ˜3 -6.5 MeV/nucleon. Evaporation residues produced in each foil were identified by the off-line γ -ray spectrometry. Measured cross section data of the residues were compared with the theoretical model calculations based on the equilibrium (EQ) and pre-equilibrium (PEQ) reaction mechanisms. Results: The experimental cross section of Rh 101 m,100 ,99 m,97 ,Ru,9597,Tc 99 m,96 ,95 ,94 ,93 m+g , and 93mMo residues measured at various projectile energies were satisfactorily reproduced by the simplified coupled channel approach in comparison to single barrier penetration model calculation. Significant cross section enhancement in the α -emitting channels was observed compared to EQ and PEQ model calculations throughout observed energy region. The ICF process over CF was analyzed by comparing with EMPIRE. The increment of the incomplete fusion fraction was observed with increasing projectile energies. Conclusions: Theoretical model calculations reveal that the compound reaction mechanism is the major contributor to the production of residues in 7Li+natMo reaction. Theoretical evaluations substantiate the contribution of ICF over the CF in α -emitting channels. EMPIRE estimations shed light on its predictive capability of cross sections of the residues from the heavy-ion induced reactions.

Improved algorithm of ray tracing in ICF cryogenic targets

NASA Astrophysics Data System (ADS)

Zhang, Rui; Yang, Yongying; Ling, Tong; Jiang, Jiabin

2016-10-01

The high precision ray tracing inside inertial confinement fusion (ICF) cryogenic targets plays an important role in the reconstruction of the three-dimensional density distribution by algebraic reconstruction technique (ART) algorithm. The traditional Runge-Kutta methods, which is restricted by the precision of the grid division and the step size of ray tracing, cannot make an accurate calculation in the case of refractive index saltation. In this paper, we propose an improved algorithm of ray tracing based on the Runge-Kutta methods and Snell's law of refraction to achieve high tracing precision. On the boundary of refractive index, we apply Snell's law of refraction and contact point search algorithm to ensure accuracy of the simulation. Inside the cryogenic target, the combination of the Runge-Kutta methods and self-adaptive step algorithm are employed for computation. The original refractive index data, which is used to mesh the target, can be obtained by experimental measurement or priori refractive index distribution function. A finite differential method is performed to calculate the refractive index gradient of mesh nodes, and the distance weighted average interpolation methods is utilized to obtain refractive index and gradient of each point in space. In the simulation, we take ideal ICF target, Luneberg lens and Graded index rod as simulation model to calculate the spot diagram and wavefront map. Compared the simulation results to Zemax, it manifests that the improved algorithm of ray tracing based on the fourth-order Runge-Kutta methods and Snell's law of refraction exhibits high accuracy. The relative error of the spot diagram is 0.2%, and the peak-to-valley (PV) error and the root-mean-square (RMS) error of the wavefront map is less than λ/35 and λ/100, correspondingly.

Viscosity Control Experiment Feasibility Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, Heidi E.; Bradley, Paul Andrew

Turbulent mix has been invoked to explain many results in Inertial Confinement Fusion (ICF) and High Energy Density (HED) physics, such as reduced yield in capsule implosions. Many ICF capsule implosions exhibit interfacial instabilities seeded by the drive shock, but it is not clear that fully developed turbulence results from this. Many simulations use turbulent mix models to help match simulation results to data, but this is not appropriate if turbulence is not present. It would be useful to have an experiment where turbulent mixing could be turned on or off by design. The use of high-Z dopants to modifymore » viscosity and the resulting influence on turbulence is considered here. A complicating factor is that the plasma in some implosions can become strongly coupled, which makes the Spitzer expression for viscosity invalid. We first consider equations that cover a broad parameter space in temperature and density to address regimes for various experimental applications. Next, a previous shock-tube and other ICF experiments that investigate viscosity or use doping to examine the effects on yield are reviewed. How viscosity and dopants play a role in capsule yield depends on the region and process under consideration. Experiments and simulations have been performed to study the effects of viscosity on both the hot spot and the fuel/ablator mix. Increases in yield have been seen for some designs, but not all. We then discuss the effect of adding krypton dopant to the gas region of a typical OMEGA and a 2-shock NIF implosion to determine approximately the effect of adding dopant on the computed Reynolds number. Recommendations for a path forward for possible experiments using high-Z dopants to affect viscosity and turbulence are made.« less

Experimental Test in a Tokamak of Fusion with Spin-Polarized D and 3He

NASA Astrophysics Data System (ADS)

Honig, Arnold; Sandorfi, Andrew

2007-06-01

An experiment to test polarization retention of highly polarized D and 3He fusion fuels prior to their fusion reactions in a tTokamak is in preparation. The fusion reaction rate with 100% vector polarized reactants is expected from simple theory to increase by a factor of 1.5. With presently available polarizations, fusion reaction enhancements of ˜15% are achievable and of significant interest, while several avenues for obtaining higher polarizations are open. The potential for survival of initial fusion fuel polarizations at ˜108 K plasma core temperatures (˜5KeV) throughout the time interval preceding fusion burn was addressed in a seminal paper in 1982. While the positive conclusion from those calculations suggests that reaction enhancements are indeed feasible, this crucial factor has never been tested in a high temperature plasma core because of difficulties in preparation and injection of sufficiently polarized fusion fuels into a high temperature reactorfusion plasma. Our solution to these problems employs a new source of highly polarized D in the form of solid HD which has been developed and used in our laboratories. Solid HD is compatible with fusion physics in view of its simplicity of elemental composition and very long (weeks) relaxation times at 4K temperature, allowing efficient polarization-preserving cold-transfer operations. Containment and polarization of the HD within polymer capsules, similar to those used in inertial confinement fusion (ICF), is an innovation which simplifies the cold-transfer of polarized fuel from the dilution refrigerator polarization-production apparatus to other liquid helium temperature cryostats, for storage, transport and placement into the barrel of a cryogenic pellet gun for firing at high velocity into the reactor. The other polarized fuel partner, 3He, has been prepared as a polarized gas for applications including high-energy polarized targets and magnetic resonance imaging (MRI) scans. It will be introduced into the reactor by loading at high pressure into a thick-walled ICF-type polymer shell for injection into the plasma core with a room temperature injection gun. Based on current experience, polarizations of both D and 3He of ˜55% are projected, producing a fusion yield increase of about 15%. A collaboration is being developed for implementing this experiment at the DIII-D Ttokamak experiment at San Diego, operated by General Atomics for the U.S. Department of Energy. Calculations indicate a 10% fusion yield increase in the 14.6 MeV protons from the D-3He reaction will provide a statistically significant test of polarization retention in the plasma. Injection of the polarized fuels into a 4He or 1H plasma improves the discrimination of the effects of polarized fuels. Details of the HD fuel preparation, of the polarization processes, and of the injection into the plasma will beare presented. If the expected fusion reaction yield increase indicative of polarization retention is detected, a route to significantly improved second generation D-3He fusion would be established, as well as confidence to undertake the more difficult polarization of tritium, which would offer important cost savings and improved prospects of ignition in the ITER program.

Downscattered Neutron Imaging for ICF

NASA Astrophysics Data System (ADS)

Moran, Michael; Haan, Steven; Hatchett, Stephen; Izumi, Nobuhiko; Koch, Jeffrey; Lerche, Richard; Phillips, Thomas

2002-11-01

Diagnostics which measure the performance of implosions are critical for the success of ignition. Neutron yield, fusion-burn time history, and images are examples of important diagnostics. Neutron and x-ray images will record the geometries of compressed targets during the fusion-burn process. Such images provide a critical test of the accuracy of numerical modeling of ICF experiments. Imaging of downscattered neutrons, by using energy-resolved detection, offers the intriguing advantage of being able to provide independent images of burning and non-burning regions of the nuclear fuel. The usefulness of downscattered neutron imaging depends on both the information content of the data and on the quality of the data that can be recorded. The information content will relate to the characteristic neutron spectra that are associated with emission from different regions of the source. Numerical modeling of ICF fusion burn will be required to interpret the corresponding energy-dependent images. The exercise will be useful only if the images can be recorded with sufficient definition to reveal the spatial and energy-dependent features of interest. Several options are being evaluated with respect to the feasibility of providing the desired simultaneous spatial and energy resolution. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Recent developments in high average power driver technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prestwich, K.R.; Buttram, M.T.; Rohwein, G.J>

1979-01-01

Inertial confinement fusion (ICF) reactors will require driver systems operating with tens to hundreds of megawatts of average power. The pulse power technology that will be required to build such drivers is in a primitive state of development. Recent developments in repetitive pulse power are discussed. A high-voltage transformer has been developed and operated at 3 MV in a single pulse experiment and is being tested at 1.5 MV, 5 kj and 10 pps. A low-loss, 1 MV, 10 kj, 10 pps Marx generator is being tested. Test results from gas-dynamic spark gaps that operate both in the 100 kVmore » and 700 kV range are reported. A 250 kV, 1.5 kA/cm/sup 2/, 30 ns electron beam diode has operated stably for 1.6 x 10/sup 5/ pulses.« less

Effect of Symmetry on Performance of Imploding Capsules using the Big Foot Design

NASA Astrophysics Data System (ADS)

Khan, Shahab; Casey, Daniel; Baker, Kevin; Thomas, Cliff; Nora, Ryan; Spears, Brian; Benedetti, Laura; Izumi, Nobuhiko; Ma, Tammy; Nagel, Sabrina; Pak, Arthur; National Ignition Facility Collaboration

2017-10-01

At the National Ignition Facility, several simultaneous designs are investigated for optimizing Inertial Confinement Fusion (ICF) energy gain of indirectly driven imploding fuel capsules. Relatively high neutron yield has been achieved while exhibiting a non-symmetric central core and/or shell. While developing the ``Big Foot'' design, several tuning steps were undertaken to minimize the asymmetry of both the central hot core as well as the shell. Surrogate capsules (symcaps) were utilized in the 2-D Radiography platform to assess both the shell and central core symmetry. The results of the tuning experiments are presented. In addition, a comparison of performance and shape metrics demonstrates that improving symmetry of the implosion can yield better 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. LLNL-ABS-683471.

Cross-Beam Energy Transfer Driven by Incoherent Laser Beams with Frequency Detuning

NASA Astrophysics Data System (ADS)

Maximov, A.; Myatt, J. F.; Short, R. W.; Igumenshchev, I. V.; Seka, W.

2015-11-01

In the direct-drive method of the inertial confinement fusion (ICF), the coupling of laser energy to target plasmas is strongly influenced by the effect of cross-beam energy transfer (CBET) between multiple driving laser beams. The laser -plasma interaction (LPI) model of CBET is based on the nonparaxial laser light propagation coupled with the low-frequency ion-acoustic-domain plasma response. Common ion waves driven by multiple laser beams play a very important role in CBET. The effect of the frequency detuning (colors) in the driving laser beams is studied and it is shown to significantly reduce the level of common ion waves and therefore the level of CBET. The differences between the LPI-based CBET model and the ray-based CBET model used in hydrocodes are discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

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

NASA Astrophysics Data System (ADS)

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.

Overlapped optics induced perfect coherent effects.

PubMed

Li, Jian Jie; Zang, Xiao Fei; Mao, Jun Fa; Tang, Min; Zhu, Yi Ming; Zhuang, Song Lin

2013-12-20

For traditional coherent effects, two separated identical point sources can be interfered with each other only when the optical path difference is integer number of wavelengths, leading to alternate dark and bright fringes for different optical path difference. For hundreds of years, such a perfect coherent condition seems insurmountable. However, in this paper, based on transformation optics, two separated in-phase identical point sources can induce perfect interference with each other without satisfying the traditional coherent condition. This shifting illusion media is realized by inductor-capacitor transmission line network. Theoretical analysis, numerical simulations and experimental results are performed to confirm such a kind of perfect coherent effect and it is found that the total radiation power of multiple elements system can be greatly enhanced. Our investigation may be applicable to National Ignition Facility (NIF), Inertial Confined Fusion (ICF) of China, LED lighting technology, terahertz communication, and so on.

Design of a Neutron Temporal Diagnostic for measuring DD or DT burn histories at the NIF

NASA Astrophysics Data System (ADS)

Lahmann, B.; Frenje, J. A.; Sio, H.; Petrasso, R. D.; Bradley, D. K.; Le Pape, S.; MacKinnon, A. J.; Isumi, N.; Macphee, A.; Zayas, C.; Spears, B. K.; Hermann, H.; Hilsabeck, T. J.; Kilkenny, J. D.

2015-11-01

The DD or DT burn history in Inertial Confinement Fusion (ICF) implosions provides essential information about implosion performance and helps to constrain numerical modeling. The capability of measuring this burn history is thus important for the NIF in its pursuit of ignition. Currently, the Gamma Reaction History (GRH) diagnostic is the only system capable of measuring the burn history for DT implosions with yields greater than ~ 1e14. To complement GRH, a new NIF Neutron Temporal Diagnostic (NTD) is being designed for measuring the DD or DT burn history with yields greater than ~ 1e10. A traditional scintillator-based design and a pulse-dilation-based design are being considered. Using MCNPX simulations, both designs have been optimized, validated and contrasted for various types of implosions at the NIF. This work was supported in part by the U.S. DOE, LLNL and LLE.

Thermonuclear Reaction Rate of T(t,2n) α Measured in ICF Plasmas

NASA Astrophysics Data System (ADS)

Brune, C. R.; Casey, D. T.; Caggiano, J. A.; Hatarik, R.; McNabb, D. P.; Sayre, D. B.; Smalyuk, V. A.; Bacher, A. D.; Frenje, J. A.; Gatu-Johnson, M.; Zylstra, A. B.; Couder, M.

2014-09-01

Measurements of charged-particle reactivity have been performed in inertial confinement fusion experiments at the National Ignition Facility. Time-of-flight detectors were used to measure neutrons from the T(t,2n) and T(d,n) reactions produced by implosions with tritium-filled targets (0.1% deuterium). Along with the measured target fuel composition and reactant ion temperature, the well-known T(d,n) reactivity was used to convert the measured neutron yields into a T(t,2n) reactivity. The ion temperature was determined to be 3.3(3) keV, corresponding to an effective energy of 16 keV. In comparison to accelerator measurements of the low-energy T(t,2n) cross section, the source of all previous data, our experiment has resulted in T(t,2n) data with better statistics and lower backgrounds.

SABRE, a 10-MV linear induction accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corely, J.P.; Alexander, J.A.; Pankuch, P.J.

SABRE (Sandia Accelerator and Beam Research Experiment) is a 10-MV, 250-kA, 40-ns linear induction accelerator. It was designed to be used in positive polarity output. Positive polarity accelerators are important for application to Sandia's ICF (Inertial Confinement Fusion) and LMF (Laboratory Microfusion Facility) program efforts. SABRE was built to allow a more detailed study of pulsed power issues associated with positive polarity output machines. MITL (Magnetically Insulated Transmission Line) voltage adder efficiency, extraction ion diode development, and ion beam transport and focusing. The SABRE design allows the system to operate in either positive polarity output for ion extraction applications ormore » negative polarity output for more conventional electron beam loads. Details of the design of SABRE and the results of initial machine performance in negative polarity operation are presented in this paper. 13 refs., 12 figs., 1 tab.« less

Resolving Controversies Concerning the Kinetic Structure of Multi-Ion Plasma Shocks

NASA Astrophysics Data System (ADS)

Keenan, Brett; Simakov, Andrei; Chacon, Luis; Taitano, William

2017-10-01

Strong collisional shocks in multi-ion plasmas are featured in several high-energy-density environments, including Inertial Confinement Fusion (ICF) implosions. Yet, basic structural features of these shocks remain poorly understood (e.g., the shock width's dependence on the Mach number and the plasma ion composition, and temperature decoupling between ion species), causing controversies in the literature; even for stationary shocks in planar geometry [cf., Ref. and Ref.]. Using a LANL-developed, high-fidelity, 1D-2V Vlasov-Fokker-Planck code (iFP), as well as direct comparisons to multi-ion hydrodynamic simulations and semi-analytic predictions, we critically examine steady-state, planar shocks in two-ion species plasmas and put forward resolutions to these controversies. This work was supported by the Los Alamos National Laboratory LDRD Program, Metropolis Postdoctoral Fellowship for W.T.T., and used resources provided by the Los Alamos National Laboratory Institutional Computing Program.

FY96-98 Summary Report Mercury: Next Generation Laser for High Energy Density Physics SI-014

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayramian, A.; Beach, R.; Bibeau, C.

The scope of the Mercury Laser project encompasses the research, development, and engineering required to build a new generation of diode-pumped solid-state lasers for Inertial Confinement Fusion (ICF). The Mercury Laser will be the first integrated demonstration of laser diodes, crystals, and gas cooling within a scalable laser architecture. This report is intended to summarize the progress accomplished during the first three years of the project. Due to the technological challenges associated with production of 900 nm diode-bars, heatsinks, and high optical-quality Yb:S-FAP crystals, the initial focus of the project was primarily centered on the R&D in these three areas.more » During the third year of the project, the R&D continued in parallel with the development of computer codes, partial activation of the laser, component testing, and code validation where appropriate.« less

Nonlinear plasma wave models in 3D fluid simulations of laser-plasma interaction

NASA Astrophysics Data System (ADS)

Chapman, Thomas; Berger, Richard; Arrighi, Bill; Langer, Steve; Banks, Jeffrey; Brunner, Stephan

2017-10-01

Simulations of laser-plasma interaction (LPI) in inertial confinement fusion (ICF) conditions require multi-mm spatial scales due to the typical laser beam size and durations of order 100 ps in order for numerical laser reflectivities to converge. To be computationally achievable, these scales necessitate a fluid-like treatment of light and plasma waves with a spatial grid size on the order of the light wave length. Plasma waves experience many nonlinear phenomena not naturally described by a fluid treatment, such as frequency shifts induced by trapping, a nonlinear (typically suppressed) Landau damping, and mode couplings leading to instabilities that can cause the plasma wave to decay rapidly. These processes affect the onset and saturation of stimulated Raman and Brillouin scattering, and are of direct interest to the modeling and prediction of deleterious LPI in ICF. It is not currently computationally feasible to simulate these Debye length-scale phenomena in 3D across experimental scales. Analytically-derived and/or numerically benchmarked models of processes occurring at scales finer than the fluid simulation grid offer a path forward. We demonstrate the impact of a range of kinetic processes on plasma reflectivity via models included in the LPI simulation code pF3D. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

First-principles equation-of-state table of beryllium based on density-functional theory calculations

DOE PAGES

Ding, Y. H.; Hu, S. X.

2017-06-06

Beryllium has been considered a superior ablator material for inertial confinement fusion (ICF) target designs. An accurate equation-of-state (EOS) of beryllium under extreme conditions is essential for reliable ICF designs. Based on density-functional theory (DFT) calculations, we have established a wide-range beryllium EOS table of density ρ = 0.001 to 500 g/cm 3 and temperature T = 2000 to 10 8 K. Our first-principle equation-of-state (FPEOS) table is in better agreement with the widely used SESAME EOS table (SESAME 2023) than the average-atom INFERNO and Purgatorio models. For the principal Hugoniot, our FPEOS prediction shows ~10% stiffer than the lastmore » two models in the maximum compression. Although the existing experimental data (only up to 17 Mbar) cannot distinguish these EOS models, we anticipate that high-pressure experiments at the maximum compression region should differentiate our FPEOS from INFERNO and Purgatorio models. Comparisons between FPEOS and SESAME EOS for off-Hugoniot conditions show that the differences in the pressure and internal energy are within ~20%. By implementing the FPEOS table into the 1-D radiation–hydrodynamic code LILAC, we studied in this paper the EOS effects on beryllium-shell–target implosions. Finally, the FPEOS simulation predicts higher neutron yield (~15%) compared to the simulation using the SESAME 2023 EOS table.« less

History of HERMES III diode to z-pinch breakthrough and beyond :

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanford, Thomas Williamlou.

HERMES III and Z are two flagship accelerators of Sandias pulsed-power program developed to generate intense -ray fields for the study of nuclear radiation effects, and to explore high energy-density physics (including the production of intense x-ray fields for Inertia Confinement Fusion [ICF]), respectively. A diode at the exit of HERMES III converts its 20-MeV electron beam into -rays. In contrast, at the center of Z, a z-pinch is used to convert its 20-MA current into an intense burst of x-rays. Here the history of how the HERMES III diode emerged from theoretical considerations to actual hardware is discussed. Next,more » the reverse process of how the experimental discovery of wire-array stabilization in a z-pinch, led to a better theory of wirearray implosions and its application to one of the ICF concepts on Z--the DH (Dynamic Hohlraum) is reviewed. Lastly, the report concludes with how the unexpected axial radiation asymmetry measured in the DH is understood. The first discussion illustrates the evolution of physics from theory-to-observationto- refinement. The second two illustrate the reverse process of observationto- theory-to refinement. The histories are discussed through the vehicle of my research at Sandia, illustrating the unique environment Sandia provides for personal growth and development into a scientific leader.« less

Rayleigh Taylor growth at an embedded interface driven by a radiative shock

NASA Astrophysics Data System (ADS)

Huntington, Channing

2016-10-01

Radiative shocks are those where the radiation generated by the shock influences the hydrodynamics of the matter in the system. Radiative shocks are common in astrophysics, including during type II supernovae, and have also been observed in the rebound phase of a compressed inertial confinement fusion (ICF) capsule. It is predicted that the radiative heating serves to stabilize hydrodynamic instabilities in these systems, but studying the effect is challenging. Only in recent experiments at the National Ignition Facility has the energy been available to drive a radiative shock across a planar, Rayleigh-Taylor unstable interface in solid-density materials. Because the generation of radiation at the shock front is a strong function of shock velocity (v8) , the RT growth rates in the presence of fast and slow shockas were directly compared. We observe reduced RT spike development when the driving shock is expected to be radiative. Both low drive (225 eV) hydrodynamic RT growth and high drive (325 eV), radiatively-stabilized growth rates are in good agreement with 2D models. This NIF Discovery Science result has important implications for our understanding of astrophysical radiative shocks, as well as the dynamics of ICF capsules. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

First-principles equation-of-state table of beryllium based on density-functional theory calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, Y. H.; Hu, S. X.

Beryllium has been considered a superior ablator material for inertial confinement fusion (ICF) target designs. An accurate equation-of-state (EOS) of beryllium under extreme conditions is essential for reliable ICF designs. Based on density-functional theory (DFT) calculations, we have established a wide-range beryllium EOS table of density ρ = 0.001 to 500 g/cm 3 and temperature T = 2000 to 10 8 K. Our first-principle equation-of-state (FPEOS) table is in better agreement with the widely used SESAME EOS table (SESAME 2023) than the average-atom INFERNO and Purgatorio models. For the principal Hugoniot, our FPEOS prediction shows ~10% stiffer than the lastmore » two models in the maximum compression. Although the existing experimental data (only up to 17 Mbar) cannot distinguish these EOS models, we anticipate that high-pressure experiments at the maximum compression region should differentiate our FPEOS from INFERNO and Purgatorio models. Comparisons between FPEOS and SESAME EOS for off-Hugoniot conditions show that the differences in the pressure and internal energy are within ~20%. By implementing the FPEOS table into the 1-D radiation–hydrodynamic code LILAC, we studied in this paper the EOS effects on beryllium-shell–target implosions. Finally, the FPEOS simulation predicts higher neutron yield (~15%) compared to the simulation using the SESAME 2023 EOS table.« less

Monte Carlo Modeling of Non-Local Electron Conduction in High Energy Density Plasmas

NASA Astrophysics Data System (ADS)

Chenhall, Jeffrey John

The implicit SNB (iSNB) non-local multigroup thermal electron conduction method of Schurtz et. al. [Phys. Plasmas 7, 4238 (2000)] and Cao et. al. [Phys. Plasmas 22, 082308 (2015)] is adapted into an electron thermal transport Monte Carlo (ETTMC) transport method to better model higher order angular and long mean free path non-local effects. The ETTMC model is used to simulate the electron thermal transport within inertial confinement fusion (ICF) type problems. The new model aims to improve upon the currently used iSNB, in particular by using finite particle ranges in comparison to the exponential solution of a diffusion method and by improved higher order angular modeling. The new method has been implemented in the 1D LILAC and 2D DRACO multiphysics production codes developed by the University of Rochester Laboratory for Laser Energetics. The ETTMC model is compared to iSNB for several direct drive ICF type simulations: Omega shot 60303 a shock timing experiment, Omega shot 59529 a shock timing experiment, Omega shot 68951 a cryogenic target implosion and a NIF polar direct drive phase plate design. Overall, the ETTMC method performs at least as well as the iSNB method and predicts lower preheating ahead of the shock fronts. This research was supported by University of Rochester Laboratory for Laser Energetics, Sandia National Laboratories and the University of Wisconsin-Madison Foundation.

Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas

DOE PAGES

Rojas-Herrera, J.; Rinderknecht, H. G.; Zylstra, A. B.; ...

2015-03-01

The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray uences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-K α and K β x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those notmore » exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.« less

Monochromatic x-ray radiography of laser-driven spherical targets using high-energy, picoseconds LFEX laser

NASA Astrophysics Data System (ADS)

Sawada, Hiroshi; Fujioka, S.; Lee, S.; Arikawa, Y.; Shigemori, K.; Nagatomo, H.; Nishimura, H.; Sunahara, A.; Theobald, W.; Perez, F.; Patel, P. K.; Beg, F. N.

2015-11-01

Formation of a high density fusion fuel is essential in both conventional and advanced Inertial Confinement Fusion (ICF) schemes for the self-sustaining fusion process. In cone-guided Fast Ignition (FI), a metal cone is attached to a spherical target to maintain the path for the injection of an intense short-pulse ignition laser from blow-off plasma created when nanoseconds compression lasers drive the target. We have measured a temporal evolution of a compressed deuterated carbon (CD) sphere using 4.5 keV K-alpha radiography with the Kilo-Joule, picosecond LFEX laser at the Institute of Laser Engineering. A 200 μm CD sphere attached to the tip of a Au cone was directly driven by 9 Gekko XII beams with 300 J/beam in a 1.3 ns Gaussian pulse. The LFEX laser irradiated on a Ti foil to generate 4.51 Ti K-alpha x-ray. By varying the delay between the compression and backlighter lasers, the measured radiograph images show an increase of the areal density of the imploded target. The detail of the quantitative analyses to infer the areal density and comparisons to hydrodynamics simulations will be presented. This work was performed with the support and under the auspices of the NIFS Collaboration Research program (NIFS13KUGK072). H.S. was supported by the UNR's International Activities Grant program.

A 1-D Study of the Ignition Space for Magnetic Indirect (X-ray) Drive Targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobble, James Allen; Sinars, Daniel Brian

The ICF program today is investigating three approaches to achieving multi-MJ fusion yields and ignition: (1) laser indirect (x-ray) drive on the National Ignition Facility (NIF), (2) laser direct drive (primarily on the Omega laser facility at the University of Rochester), and (3) magnetic direct drive on the Z pulsed power facility. In this white paper we briefly consider a fourth approach, magnetic indirect drive, in which pulsedpower- driven x-ray sources are used in place of laser driven sources. We first look at some of the x-ray sources studied on Z prior to 2007 before the pulsed power ICF programmore » shifted to magnetic direct drive. We then show results from a series of 1D Helios calculations of double-shell capsules that suggest that these sources, scaled to higher temperatures, could be a promising path to achieving multi-MJ fusion yields and ignition. We advocate here that more detailed design calculations with widely accepted 2D/3D ICF codes should be conducted for a better assessment of the prospects.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prasad, M.K.; Kershaw, D.S.; Shaw, M.J.

The authors present detailed features of the ICF3D hydrodynamics code used for inertial fusion simulations. This code is intended to be a state-of-the-art upgrade of the well-known fluid code, LASNEX. ICF3D employs discontinuous finite elements on a discrete unstructured mesh consisting of a variety of 3D polyhedra including tetrahedra, prisms, and hexahedra. The authors discussed details of how the ROE-averaged second-order convection was applied on the discrete elements, and how the C++ coding interface has helped to simplify implementing the many physics and numerics modules within the code package. The author emphasized the virtues of object-oriented design in large scalemore » projects such as ICF3D.« less

Enhancing Ignition Probability and Fusion Yield in NIF Indirect Drive Targets with Applied Magnetic Fields

NASA Astrophysics Data System (ADS)

Perkins, L. John; Logan, B. Grant; Ho, Darwin; Zimmerman, George; Rhodes, Mark; Blackfield, Donald; Hawkins, Steven

2017-10-01

Imposed magnetic fields of tens of Tesla that increase to greater than 10 kT (100 MGauss) under capsule compression may relax conditions for ignition and propagating burn in indirect-drive ICF targets. This may allow attainment of ignition, or at least significant fusion energy yields, in presently-performing ICF targets on the National Ignition Facility that today are sub-marginal for thermonuclear burn through adverse hydrodynamic conditions at stagnation. Results of detailed 2D radiation-hydrodynamic-burn simulations applied to NIF capsule implosions with low-mode shape perturbations and residual kinetic energy loss indicate that such compressed fields may increase the probability for ignition through range reduction of fusion alpha particles, suppression of electron heat conduction and stabilization of higher-mode RT instabilities. Optimum initial applied fields are around 50 T. Off-line testing has been performed of a hohlraum coil and pulsed power supply that could be integrated on NIF; axial fields of 58T were obtained. Given the full plasma structure at capsule stagnation may be governed by 3-D resistive MHD, the formation of closed magnetic field lines might further augment ignition prospects. Experiments are now required to assess the potential of applied magnetic fields to NIF ICF ignition and burn. Work performed under auspices of U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Quantitative studies of kinetic effects in direct- and indirect-drive Inertial Confinement Fusion implosions

NASA Astrophysics Data System (ADS)

Rinderknecht, Hans

2013-10-01

A comprehensive set of experiments using shock-driven implosions has been conducted to quantitatively study kinetic effects by exploring deviations from hydrodynamic behavior in plasmas relevant to inertial confinement fusion (ICF). Two types of targets were imploded at OMEGA to create ~10 keV, ~1022 cm-3 plasmas with conditions comparable to the incipient hotspot in ignition designs: thin-glass targets filled with mixtures of D2 and 3He gas; and thin deuterated-plastic shells filled with 3He. In the thin-glass experiments, the gas pressure was varied from 1 to 25 atm to scan the ion-mean-free path in the plasma at shock burn. The observed nuclear yields and temperatures deviated more strongly from hydrodynamic predictions as the ion-mean-free path increased to the order of the plasma size. This result provides the first direct experimental evidence how kinetic effects impact yields and ion temperature. The ratio of D to 3He was also varied while maintaining the fuel mass density. As the D fraction was reduced, the DD and D3He fusion products displayed an anomalous yield reduction. Separation of the D and 3He ion species across the strong (Mach ~10) shock-front will be discussed as the likely cause of this result. Finally, thin-CD shells filled with 3He produced significantly more D3He-protons when imploded than is explained by hydrodynamic mix models. This result suggests a kinetic form of mix dominates at the strongly-shocked shell-gas interface. This work was performed in collaboration with C. Li, M. Rosenberg, A. Zylstra, H. Sio, M. Gatu Johnson, F. Séguin, J. Frenje, and R. Petrasso (MIT), V. Glebov, C. Stoeckl, J. Delettrez, and C. Sangster (LLE), J. Pino, P. Amendt, C. Bellei, and S. Wilks (LLNL), G. Kagan, N. Hoffmann and K. Molvig (LANL), and A. Nikroo (GA) and was supported in part by the NLUF, FSC/UR, U.S. DOE, LLNL and LLE.

Measurement of excitation functions of evaporation residues in the 16O+124Sn reaction and investigation of the dependence of incomplete fusion dynamics on entrance channel parameters

NASA Astrophysics Data System (ADS)

Singh, D.; Linda, Sneha B.; Giri, Pankaj K.; Mahato, Amritraj; Tripathi, R.; Kumar, Harish; Tali, Suhail A.; Parashari, Siddharth; Ali, Asif; Dubey, Rakesh; Ansari, M. Afzal; Kumar, R.; Muralithar, S.; Singh, R. P.

2018-06-01

Excitation functions for the 11 evaporation residues populated through complete and/or incomplete fusion in 16O+124Sn system at low projectile energies ≈3 -7 MeV /nucleon have been measured. Recoil catcher activation technique followed by offline γ -ray spectrometry has been employed. Some of the evaporation residues are found to have contributions from precursor decays. The precursor contributions have been separated out from the measured cumulative cross-sections of evaporation residues. Independent cross-sections are compared with statistical model code PACE-4 predictions. The evaporation residues produced through x n and pxn channels are found to be well reproduced with the PACE-4 predictions after subtraction of precursor decay contributions. A substantial enhancement in the measured excitation functions over their theoretical predictions for the evaporation residues produced in α -emitting channels has been observed, which is attributed to the presence of incomplete fusion of projectile with target at these low energies. The present study shows that the incomplete fusion and the break-up probability of the incident 16O into α clusters (i.e., break-up of 16O into 12C+α and/or 8Be+8Be ) increases with projectile energy. The present data suggests that the deformation of target is highlighting the important role to affect the ICF reactions independently with different projectiles. The comparison of the present study with literature data also shows that the ICF probability depends on various entrance channel parameters, namely, projectile energy, entrance channel mass-asymmetry, α -Q value, Coulomb factor (ZPZT) , deformation parameter (β2), and their combinations. Moreover, the combined parameters ZPZT.β2 and μECAS.β2 are not found suitable to explain whole ICF characteristics, particularly for spherical and slightly deformed targets. On the other hand, the combined parameter ZPZT.μECAS has been found to explain more precisely the ICF dynamics as compared to other single and combined entrance channel parameters.

Power balance on a multibeam laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sampat, Sid; Kelly, John H.; Kosc, Tanya Z.

Inertial confinement fusion (ICF) cryogenic experiments on the 60-beam OMEGA laser have strict requirements for the laser energy delivered on target to be power balanced in order to maximize target-irradiation uniformity. For OMEGA, this quantity (power balance) is inferred from measurements of the time-integrated energy and time-resolved, spatially integrated temporal profile of each of the 60 beams at the output of the laser. The work presented here proposes a general definition of power balance as measured at the laser output and discusses the conditions that are fundamental to achieving laser power balance. Power balance necessitates equal gain across all stagesmore » of amplification, equal net losses across each amplifier stage, equal frequency conversion (from 1053 nm to 351 nm) of all 60 beams, and equal beam path lengths (beam timing). Typical OMEGA ICF laser pulse shapes consist of one or more short (100-ps) “pickets” followed by a shaped “drive” pulse of 1 to 2 ns. For these experiments, power balance is assessed for the pickets and the drive independently, with the ultimate goal of achieving root-mean-square (rms) imbalance across all 60 beams of less than 2% rms on both. Our work presents a comprehensive summary of laser shot campaigns conducted to significantly improve laser power balance from typical rms values of 4.7% and 5.2%, respectively, to the 3% level for both features along with a discussion of future work required to further reduce the rms power imbalance of the laser system.« less

Power balance on a multibeam laser

NASA Astrophysics Data System (ADS)

Sampat, S.; Kelly, J. H.; Kosc, T. Z.; Rigatti, A. L.; Kwiatkowski, J.; Donaldson, W. R.; Romanofsky, M. H.; Waxer, L. J.; Dean, R.; Moshier, R.

2018-02-01

Inertial confinement fusion (ICF) cryogenic experiments on the 60-beam OMEGA laser have strict requirements for the laser energy delivered on target to be power balanced in order to maximize target-irradiation uniformity. For OMEGA, this quantity (power balance) is inferred from measurements of the time-integrated energy and time-resolved, spatially integrated temporal profile of each of the 60 beams at the output of the laser. The work presented here proposes a general definition of power balance as measured at the laser output and discusses the conditions that are fundamental to achieving laser power balance. Power balance necessitates equal gain across all stages of amplification, equal net losses across each amplifier stage, equal frequency conversion (from 1053 nm to 351 nm) of all 60 beams, and equal beam path lengths (beam timing). Typical OMEGA ICF laser pulse shapes consist of one or more short (100-ps) "pickets" followed by a shaped "drive" pulse of 1 to 2 ns. For these experiments, power balance is assessed for the pickets and the drive independently, with the ultimate goal of achieving root-mean-square (rms) imbalance across all 60 beams of less than 2% rms on both. This work presents a comprehensive summary of laser shot campaigns conducted to significantly improve laser power balance from typical rms values of 4.7% and 5.2%, respectively, to the 3% level for both features along with a discussion of future work required to further reduce the rms power imbalance of the laser system.

Power balance on a multibeam laser

DOE PAGES

Sampat, Sid; Kelly, John H.; Kosc, Tanya Z.; ...

2018-02-15

Inertial confinement fusion (ICF) cryogenic experiments on the 60-beam OMEGA laser have strict requirements for the laser energy delivered on target to be power balanced in order to maximize target-irradiation uniformity. For OMEGA, this quantity (power balance) is inferred from measurements of the time-integrated energy and time-resolved, spatially integrated temporal profile of each of the 60 beams at the output of the laser. The work presented here proposes a general definition of power balance as measured at the laser output and discusses the conditions that are fundamental to achieving laser power balance. Power balance necessitates equal gain across all stagesmore » of amplification, equal net losses across each amplifier stage, equal frequency conversion (from 1053 nm to 351 nm) of all 60 beams, and equal beam path lengths (beam timing). Typical OMEGA ICF laser pulse shapes consist of one or more short (100-ps) “pickets” followed by a shaped “drive” pulse of 1 to 2 ns. For these experiments, power balance is assessed for the pickets and the drive independently, with the ultimate goal of achieving root-mean-square (rms) imbalance across all 60 beams of less than 2% rms on both. Our work presents a comprehensive summary of laser shot campaigns conducted to significantly improve laser power balance from typical rms values of 4.7% and 5.2%, respectively, to the 3% level for both features along with a discussion of future work required to further reduce the rms power imbalance of the laser system.« less

Experimental study on ablative stabilization of Rayleigh-Taylor instability of laser-irradiated targets

NASA Astrophysics Data System (ADS)

Shigemori, Keisuke; Sakaiya, Tatsuhiko; Otani, Kazuto; Fujioka, Shinsuke; Nakai, Mitsuo; Azechi, Hiroshi; Shiraga, Hiroyuki; Tamari, Yohei; Okuno, Kazuki; Sunahara, Atsushi; Nagatomo, Hideo; Murakami, Masakatsu; Nishihara, Katsunobu; Izawa, Yasukazu

2004-09-01

Hydrodynamic instabilities are key issues of the physics of inertial confinement fusion (ICF) targets. Among the instabilities, Rayleigh-Taylor (RT) instability is the most important because it gives the largest growth factor in the ICF targets. Perturbations on the laser irradiated surface grow exponentially, but the growth rate is reduced by ablation flow. The growth rate γ is written as Takabe-Betti formula: γ = [kg/(1+kL)]1/2-βkm/pa, where k is wave number of the perturbation, g is acceleration, L is density scale-length, β is a coefficient, m is mass ablation rate per unit surface, and ρa is density at the ablation front. We experimentally measured all the parameters in the formula for polystyrene (CH) targets. Experiments were done on the HIPER laser facility at Institute of Laser Engineering, Osaka University. We found that the β value in the formula is ~ 1.7, which is in good agreements with the theoretical prediction, whereas the β for certain perturbation wavelengths are larger than the prediction. This disagreement between the experiment and the theory is mainly due to the deformation of the cutoff surface, which is created by non-uniform ablation flow from the ablation surface. We also found that high-Z doped plastic targets have multiablation structure, which can reduce the RT growth rate. When a low-Z target with high-Z dopant is irradiated by laser, radiation due to the high-Z dopant creates secondary ablation front deep inside the target. Since, the secondary ablation front is ablated by x-rays, the mass ablation rate is larger than the laser-irradiated ablation surface, that is, further reduction of the RT growth is expected. We measured the RT growth rate of Br-doped polystyrene targets. The experimental results indicate that of the CHBr targets show significantly small growth rate, which is very good news for the design of the ICF targets.

Large-scale 3D simulations of ICF and HEDP targets

NASA Astrophysics Data System (ADS)

Marinak, Michael M.

2000-10-01

The radiation hydrodynamics code HYDRA continues to be developed and applied to 3D simulations of a variety of targets for both inertial confinement fusion (ICF) and high energy density physics. Several packages have been added enabling this code to perform ICF target simulations with similar accuracy as two-dimensional codes of long-time historical use. These include a laser ray trace and deposition package, a heavy ion deposition package, implicit Monte Carlo photonics, and non-LTE opacities, derived from XSN or the linearized response matrix approach.(R. More, T. Kato, Phys. Rev. Lett. 81, 814 (1998), S. Libby, F. Graziani, R. More, T. Kato, Proceedings of the 13th International Conference on Laser Interactions and Related Plasma Phenomena, (AIP, New York, 1997).) LTE opacities can also be calculated for arbitrary mixtures online by combining tabular values generated by different opacity codes. Thermonuclear burn, charged particle transport, neutron energy deposition, electron-ion coupling and conduction, and multigroup radiation diffusion packages are also installed. HYDRA can employ ALE hydrodynamics; a number of grid motion algorithms are available. Multi-material flows are resolved using material interface reconstruction. Results from large-scale simulations run on up to 1680 processors, using a combination of massively parallel processing and symmetric multiprocessing, will be described. A large solid angle simulation of Rayleigh-Taylor instability growth in a NIF ignition capsule has resolved simultaneously the full spectrum of the most dangerous modes that grow from surface roughness. Simulations of a NIF hohlraum illuminated with the initial 96 beam configuration have also been performed. The effect of the hohlraum’s 3D intrinsic drive asymmetry on the capsule implosion will be considered. We will also discuss results from a Nova experiment in which a copper sphere is crushed by a planar shock. Several interacting hydrodynamic instabilities, including the Widnall instability, cause breakup of the resulting vortex ring.

Gamma-based Measurement of ``Dark Mix'' in ICF Capsules

NASA Astrophysics Data System (ADS)

Meaney, Kevin; Herrmann, H.; Kim, Yh; Zylstra, Ab; Geppert-Kleinrath, H.; Hoffman, Nm; Yi, As

2017-10-01

Mix of capsule ablator material into the fusion fuel is a source of yield degradation in inertial confinement fusion. Jetting or chunk mix, such as the elusive ``meteors'' that have been observed at NIF, can be difficult to diagnose because the chunks may not get hot enough to excite dopant x-rays, nor atomized enough for separated-reactants to fuse. Using the gamma reaction history (GRH-6m) diagnostic, (n,n') gammas from strategically placed carbon layer within a beryllium capsule gives a measure of the time-resolved areal density of this carbon during the burn and hence an indication of the compression and spatial distribution of this layer. As the carbon moves further from the fuel, the areal density nominally decreases as 1/r2 for unablated material. However, mix of this carbon into the cold dense fuel layer or hot spot will have a significant effect on the carbon gamma signal. Different types of mix (e.g., jetting, Rayleigh-Taylor fingers, diffusive, ...) as well as features that can seed this mix (eg., tents, fill,...) will be discussed along with their expected effect on the carbon signal. The design for upcoming OMEGA shots, which will demonstrate this technique, and the potential for use on the NIF will be presented.

Two-temperature equilibration in warm dense hydrogen measured with x-ray scattering from the LCLS

NASA Astrophysics Data System (ADS)

Fletcher, Luke; High Energy Density Sciences Collaboration

2017-10-01

Understanding the properties of warm dense hydrogen plasmas is critical for modeling stellar and planetary interiors, as well as for inertial confinement fusion (ICF) experiments. Of central importance are the electron-ion collision and equilibration times that determine the microscopic properties in a high energy density state. Spectrally and angularly resolved x-ray scattering measurements from fs-laser heated hydrogen have resolved the picosecond evolution and energy relaxation from a two-temperature plasma towards thermodynamic equilibrium in the warm dense matter regime. The interaction of rapidly heated cryogenic hydrogen irradiated by a 400 nm, 5x1017 W/cm2 , 70 fs-laser is visualized with ultra-bright 5.5 kev x-ray pulses from the Linac Coherent Light (LCLS) source in 1 Hz repetition rate pump-probe setting. We demonstrate that the energy relaxation is faster than many classical binary collision theories that use ad hoc cutoff parameters used in the Landau-Spitzer determination of the Coulomb logarithm. This work was supported by the DOE Office of Science, Fusion Energy Science under contract No. SF00515 and supported under FWP 100182 and DOE Office of Basic Energy Sciences, Materials Sciences and Engineering Division, contract DE-AC02-76SF00515.

Monte Carlo charged-particle tracking and energy deposition on a Lagrangian mesh.

PubMed

Yuan, J; Moses, G A; McKenty, P W

2005-10-01

A Monte Carlo algorithm for alpha particle tracking and energy deposition on a cylindrical computational mesh in a Lagrangian hydrodynamics code used for inertial confinement fusion (ICF) simulations is presented. The straight line approximation is used to follow propagation of "Monte Carlo particles" which represent collections of alpha particles generated from thermonuclear deuterium-tritium (DT) reactions. Energy deposition in the plasma is modeled by the continuous slowing down approximation. The scheme addresses various aspects arising in the coupling of Monte Carlo tracking with Lagrangian hydrodynamics; such as non-orthogonal severely distorted mesh cells, particle relocation on the moving mesh and particle relocation after rezoning. A comparison with the flux-limited multi-group diffusion transport method is presented for a polar direct drive target design for the National Ignition Facility. Simulations show the Monte Carlo transport method predicts about earlier ignition than predicted by the diffusion method, and generates higher hot spot temperature. Nearly linear speed-up is achieved for multi-processor parallel simulations.

The first target experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Landen, O. L.; Glenzer, S. H.; Froula, D. H.; Dewald, E. L.; Suter, L. J.; Schneider, M. B.; Hinkel, D. E.; Fernandez, J. C.; Kline, J. L.; Goldman, S. R.; Braun, D. G.; Celliers, P. M.; Moon, S. J.; Robey, H. S.; Lanier, N. E.; Glendinning, S. G.; Blue, B. E.; Wilde, B. H.; Jones, O. S.; Schein, J.; Divol, L.; Kalantar, D. H.; Campbell, K. M.; Holder, J. P.; McDonald, J. W.; Niemann, C.; MacKinnon, A. J.; Collins, G. W.; Bradley, D. K.; Eggert, J. H.; Hicks, D. G.; Gregori, G.; Kirkwood, R. K.; Young, B. K.; Foster, J. M.; Hansen, J. F.; Perry, T. S.; Munro, D. H.; Baldis, H. A.; Grim, G. P.; Heeter, R. F.; Hegelich, M. B.; Montgomery, D. S.; Rochau, G. A.; Olson, R. E.; Turner, R. E.; Workman, J. B.; Berger, R. L.; Cohen, B. I.; Kruer, W. L.; Langdon, A. B.; Langer, S. H.; Meezan, N. B.; Rose, H. A.; Still, C. H.; Williams, E. A.; Dodd, E. S.; Edwards, M. J.; Monteil, M.-C.; Stevenson, R. M.; Thomas, B. R.; Coker, R. F.; Magelssen, G. R.; Rosen, P. A.; Stry, P. E.; Woods, D.; Weber, S. V.; Young, P. E.; Alvarez, S.; Armstrong, G.; Bahr, R.; Bourgade, J.-L.; Bower, D.; Celeste, J.; Chrisp, M.; Compton, S.; Cox, J.; Constantin, C.; Costa, R.; Duncan, J.; Ellis, A.; Emig, J.; Gautier, C.; Greenwood, A.; Griffith, R.; Holdner, F.; Holtmeier, G.; Hargrove, D.; James, T.; Kamperschroer, J.; Kimbrough, J.; Landon, M.; Lee, F. D.; Malone, R.; May, M.; Montelongo, S.; Moody, J.; Ng, E.; Nikitin, A.; Pellinen, D.; Piston, K.; Poole, M.; Rekow, V.; Rhodes, M.; Shepherd, R.; Shiromizu, S.; Voloshin, D.; Warrick, A.; Watts, P.; Weber, F.; Young, P.; Arnold, P.; Atherton, L.; Bardsley, G.; Bonanno, R.; Borger, T.; Bowers, M.; Bryant, R.; Buckman, S.; Burkhart, S.; Cooper, F.; Dixit, S. N.; Erbert, G.; Eder, D. C.; Ehrlich, R. E.; Felker, B.; Fornes, J.; Frieders, G.; Gardner, S.; Gates, C.; Gonzalez, M.; Grace, S.; Hall, T.; Haynam, C. A.; Heestand, G.; Henesian, M. A.; Hermann, M.; Hermes, G.; Huber, S.; Jancaitis, K.; Johnson, S.; Kauffman, B.; Kelleher, T.; Kohut, T.; Koniges, A. E.; Labiak, T.; Latray, D.; Lee, A.; Lund, D.; Mahavandi, S.; Manes, K. R.; Marshall, C.; McBride, J.; McCarville, T.; McGrew, L.; Menapace, J.; Mertens, E.; Murray, J.; Neumann, J.; Newton, M.; Opsahl, P.; Padilla, E.; Parham, T.; Parrish, G.; Petty, C.; Polk, M.; Powell, C.; Reinbachs, I.; Rinnert, R.; Riordan, B.; Ross, G.; Robert, V.; Tobin, M.; Sailors, S.; Saunders, R.; Schmitt, M.; Shaw, M.; Singh, M.; Spaeth, M.; Stephens, A.; Tietbohl, G.; Tuck, J.; van Wonterghem, B. M.; Vidal, R.; Wegner, P. J.; Whitman, P.; Williams, K.; Winward, K.; Work, K.; Wallace, R.; Nobile, A.; Bono, M.; Day, B.; Elliott, J.; Hatch, D.; Louis, H.; Manzenares, R.; O'Brien, D.; Papin, P.; Pierce, T.; Rivera, G.; Ruppe, J.; Sandoval, D.; Schmidt, D.; Valdez, L.; Zapata, K.; MacGowan, B. J.; Eckart, M. J.; Hsing, W. W.; Springer, P. T.; Hammel, B. A.; Moses, E. I.; Miller, G. H.

2007-08-01

A first set of shock timing, laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and X-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in flattop and shaped 1 9 ns pulses focused with various beam smoothing options. The experiments have demonstrated excellent agreement between measured and predicted laser-target coupling in foils and hohlraums, even when extended to a longer pulse regime unattainable at previous laser facilities, validated the predicted effects of beam smoothing on intense laser beam propagation in long scale-length plasmas and begun to test 3D codes by extending the study of laser driven hydrodynamic jets to 3D geometries.

Identification of Cr valence states in Cr and Nd co-doped Lu3Al5O12 laser ceramics

NASA Astrophysics Data System (ADS)

Zhang, Pande; Jiang, Benxue; Fan, Jintai; Mao, Xiaojian; Zhang, Long

2017-09-01

Cr and Nd co-doped laser ceramics, as the potential gain materials in inertial confinement fusion (ICF), have been widely investigated. And the study on valence states of chromium ions is important. The effects of sintering additives and annealing atmosphere on the valence state of chromium were studied in detail, and the results shown that the Cr valence states were demonstrated to be Cr2+ and Cr3+ ions in HIP-sintered Cr(0.2 at.%), Nd(0.8 at.%): LuAG laser ceramics. And the intensity of the near-infrared absorption band caused by Cr2+ ions was attenuated with the decreasing SiO2 concentration and increasing MgO amount. The near-infrared absorption could be eliminated by annealing in air. And the transformation of valence states of Cr ions in the Cr,Nd:LuAG ceramics were also confirmed by electron paramagnetic resonance and X-ray photoelectron spectroscopy.

Effect of Ponderomotive Terms on Heat Flux in Laser-Produced Plasmas

NASA Astrophysics Data System (ADS)

Li, G.

2005-10-01

A laser electromagnetic field introduces ponderomotive termsootnotetextV. N. Goncharov and G. Li, Phys. Plasmas 11, 5680 (2004). in the heat flux in a plasma. To account for the nonlocal effects in the ponderomotive terms, first, the kinetic equation coupled with the Maxwell equations is numerically solved for the isotropic part of the electron distribution function. Such an equation includes self-consistent electromagnetic fields and laser absorption through the inverse bremsstrahlung. Then, the anisotropic part is found by solving a simplified Fokker--Planck equation. Using the distribution function, the electric current and heat flux are obtained and substituted into the hydrocode LILAC to simulate ICF implosions. The simulation results are compared against the existing nonlocal electron conduction modelsootnotetextG. P. Schurtz, P. D. Nicola"i, and M. Busquet, Phys. Plasmas 9, 4238 (2000). and Fokker--Planck simulations. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-92SF19460.

Full-band error control and crack-free surface fabrication techniques for ultra-precision fly cutting of large-aperture KDP crystals

NASA Astrophysics Data System (ADS)

Zhang, F. H.; Wang, S. F.; An, C. H.; Wang, J.; Xu, Q.

2017-06-01

Large-aperture potassium dihydrogen phosphate (KDP) crystals are widely used in the laser path of inertial confinement fusion (ICF) systems. The most common method of manufacturing half-meter KDP crystals is ultra-precision fly cutting. When processing KDP crystals by ultra-precision fly cutting, the dynamic characteristics of the fly cutting machine and fluctuations in the fly cutting environment are translated into surface errors at different spatial frequency bands. These machining errors should be suppressed effectively to guarantee that KDP crystals meet the full-band machining accuracy specified in the evaluation index. In this study, the anisotropic machinability of KDP crystals and the causes of typical surface errors in ultra-precision fly cutting of the material are investigated. The structures of the fly cutting machine and existing processing parameters are optimized to improve the machined surface quality. The findings are theoretically and practically important in the development of high-energy laser systems in China.

New developments and applications of intense pulsed radiation sources at Sandia National Laboratories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cook, D.

In the past thirty-six months, tremendous strides have been made in x-ray production using high-current z-pinches. Today, the x-ray energy (1.9 MJ) and power (200 TW) output of the Z accelerator (formerly PBFA-II) is the largest available in the laboratory. These z-pinch x-ray sources are being developed for research into the physics of high energy density plasmas of interest in weapon behavior and in inertial confinement fusion. Beyond the Z accelerator current of 20 MA, an extrapolation to the X-1 accelerator level of 60 MA may have the potential to drive high-yield ICF reactions at affordable cost if several challengingmore » technical problems can be overcome. New developments have also taken place at Sandia in the area of high current, mm-diameter electron beams for advanced hydrodynamic radiography. On SABRE, x-ray spot diameters were less than 2 mm with a dose of 100 R at 1 meter in a 40 ns pulse.« less

Foam-lined hohlraums at the National Ignition Facility

NASA Astrophysics Data System (ADS)

Thomas, Cliff

2017-10-01

Indirect drive inertial confinement fusion (ICF) is made difficult by hohlraum wall motion, laser backscatter, x-ray preheat, high-energy electrons, and specular reflection of the incident laser (i.e. glint). To mitigate, we line the hohlraum with a low-density metal foam, or tamper, whose properties can be readily engineered (opacity, density, laser absorption, ion-acoustic damping, etc.). We motivate the use of low-density foams for these purposes, discuss their development, and present initial findings. Importantly, we demonstrate that we can fabricate a 200-500 um thick liner at densities of 10-100 mg/cm3 that could extend the capabilities of existing physics platforms. The goal of this work is to increase energy coupled to the capsule, and maximize the yield available to science missions at the National Ignition Facility. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Return current instability driven by a temperature gradient in ICF plasmas

NASA Astrophysics Data System (ADS)

Rozmus, W.; Brantov, A. V.; Sherlock, M.; Bychenkov, V. Yu

2018-01-01

Hot plasmas with strong temperature gradients in inertial confinement fusion experiments are examined for ion acoustic instabilities produced by electron heat flow. The return current instability (RCI) due to a neutralizing current of cold electrons arising in response to a large electron heat flux has been considered. First, the linear threshold and growth rates are derived in the non-local regime of thermal transport. They are compared with the results of Vlasov-Fokker-Planck (VFP) simulations in one spatial dimension. Very good agreement has been found between kinetic VFP simulations and the linear theory of the RCI. A quasi-stationary state of ion acoustic turbulence (IAT) produced by the RCI is achieved in the VFP simulations. Saturation of the RCI involves heating of ions in the tail of the ion distribution function and convection of the enhanced ion acoustic fluctuations from the unstable region of the plasma. Further evolution of the IAT and its effects on absorption and transport are also discussed.

Laser ``M'egajoule'' cryogenic target program: from target fabrication to conformation of the deuterium-tritium ice layer

NASA Astrophysics Data System (ADS)

Collier, Rémy; Durut, Frédéric; Reneaume, Benoît; Chicane, Cédric; Théobald, Marc; Breton, Olivier; Martin, Michel; Fleury, Emmanuel; Vincent-Viry, Olivier; Bachelet, Franck; Jeannot, Laurent; Geoffray, Isabelle; Botrel, Ronan; Dauteuil, Christophe; Hermerel, Cyril; Choux, Alexandre; Bednarczyk, Sophie; Legaie, Olivier

2008-11-01

For the French inertial confinement fusion (ICF) experiments, cryogenic target assemblies (CTAs) for the LMJ program are manufactured and filled at CEA Valduc (Dijon) in the cryogenic targets filling station (IRCC). They will be moved at about 20 K into a transport cryostat for cryogenic targets and will be driven from CEA/Valduc to CEA/CESTA (Bordeaux). Cryogenic targets will then be transferred by several cryogenic grippers on the cryogenic target positioner before shots. The CTA has to meet severe specifications and involves a lot of challenging tasks for its manufacture. To fill CTAs by permeation with deuterium-tritium (DT), the IRCC need to meet strict thermal, mechanical and dimensional specifications. To obtain a good combustion yield, a very homogenous DT ice layer and very smooth roughness at 1.5 K below the DT triple point are also required. This paper deals with the up to date main issues in the different fields of the LMJ cryogenic target program.

Electromagnetic Pulses Generated From Laser Target Interactions at Shenguang II Laser Facility

NASA Astrophysics Data System (ADS)

Yang, Jinwen; Li, Tingshuai; Yi, Tao; Wang, Chuanke; Yang, Ming; Yang, Weiming; Liu, Shenye; Jiang, Shaoen; Ding, Yongkun

2016-10-01

Significant electromagnetic pulses (EMP) can be generated by the intensive laser irradiating solid targets in inertial confinement fusion (ICF). To evaluate the EMP intensity and distribution in and outside the laser chamber, we designed and fabricated a discone antenna with ultra-wide bands of over 10 GHz. The return loss (S11 parameter) of this antenna was below -10 dB and could even achieve under -30 dB at 3.1 GHz. The EMP intensity in this study at 80 cm and 40 cm away from the target chamber center (TCC) reached 400 kV/m and 2000 kV/m. The current results are expected to offer preliminary information to study physics regarding laser plasma interactions and will also lay experimental foundation for EMI shielding design to protect various diagnostics. supported by the Fundamental Research Funds for the Central Universities of China (No. ZYGX2015J108) and National Natural Science Foundation of China (Nos. 11575166 and 51581140)

High-resolution imaging of a shock front in plastic by phase contrast imaging at LCLS

NASA Astrophysics Data System (ADS)

Beckwith, M.; Jiang, S.; Zhao, Y.; Schropp, A.; Fernandez-Panella, A.; Rinderknecht, H. G.; Wilks, S.; Fournier, K.; Galtier, E.; Xing, Z.; Granados, E.; Gamboa, E.; Glenzer, S. H.; Heimann, P.; Zastrau, U.; Cho, B. I.; Eggert, J. H.; Collins, G. W.; Ping, Y.

2017-10-01

Understanding the propagation of shock waves is important for many areas of high energy density physics, including inertial confinement fusion (ICF) and shock compression science. In order to probe the shock front structures in detail, a diagnostic capable of detecting both the small spatial and temporal changes in the material is required. Here we show the experiment using hard X-ray phase contrast imaging (PCI) to probe the shock wave propagation in polyimide with submicron spatial resolution. The experiment was performed at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Lightsource (LCLS). PCI together with the femtosecond time scales of x-ray free electron lasers enables the imaging of optically opaque materials that undergo rapid temporal and spatial changes. The result reveals the evolution of the density profile with time. Work performed under DOE Contract No. DE-AC52-07NA27344 with support from OFES Early Career and LLNL LDRD program.

Development of large-aperture electro-optical switch for high power laser at CAEP

NASA Astrophysics Data System (ADS)

Zhang, Xiongjun; Wu, Dengsheng; Zhang, Jun; Lin, Donghui; Zheng, Jiangang; Zheng, Kuixing

2015-02-01

Large-aperture electro-optical switch based on plasma Pockels cell (PPC) is one of important components for inertial confinement fusion (ICF) laser facility. We have demonstrated a single-pulse driven 4×1 PPC with 400mm×400mm aperture for SGIII laser facility. And four 2×1 PPCs modules with 350mm×350mm aperture have been operated in SGII update laser facility. It is different to the PPC of NIF and LMJ for its simple operation to perform Pockels effect. With optimized operation parameters, the PPCs meet the SGII-U laser requirement of four-pass amplification control. Only driven by one high voltage pulser, the simplified PPC system would be provided with less associated diagnostics, and higher reliability. To farther reduce the insert loss of the PPC, research on the large-aperture PPC based on DKDP crystal driven by one pulse is developed. And several single-pulse driven PPCs with 80mm×80mm DKDP crystal have been manufactured and operated in laser facilities.

Measurements of the Shock Release Of Quartz and Paralyene-N

NASA Astrophysics Data System (ADS)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2017-06-01

The shock and release properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies single shock or multiple shock conditions. The challenge with measuring release properties is unlike shocks which have a single interface from which to measure the properties, the release establishes gradients in the sample. The streaked x-ray imaging capability of the NIKE laser allow the interface between quartz and CH to be measured during the release, giving measurements of the interface velocity and CH density. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography Work supported by DOE/NNSA.

2D Implosion Simulations with a Kinetic Particle Code

NASA Astrophysics Data System (ADS)

Sagert, Irina; Even, Wesley; Strother, Terrance

2017-10-01

Many problems in laboratory and plasma physics are subject to flows that move between the continuum and the kinetic regime. We discuss two-dimensional (2D) implosion simulations that were performed using a Monte Carlo kinetic particle code. The application of kinetic transport theory is motivated, in part, by the occurrence of non-equilibrium effects in inertial confinement fusion (ICF) capsule implosions, which cannot be fully captured by hydrodynamics simulations. Kinetic methods, on the other hand, are able to describe both, continuum and rarefied flows. We perform simple 2D disk implosion simulations using one particle species and compare the results to simulations with the hydrodynamics code RAGE. The impact of the particle mean-free-path on the implosion is also explored. In a second study, we focus on the formation of fluid instabilities from induced perturbations. I.S. acknowledges support through the Director's fellowship from Los Alamos National Laboratory. This research used resources provided by the LANL Institutional Computing Program.

Quantifying Fusion Born Ion Populations in Magnetically Confined Plasmas using Ion Cyclotron Emission

NASA Astrophysics Data System (ADS)

Carbajal, L.; Dendy, R. O.; Chapman, S. C.; Cook, J. W. S.

2017-03-01

Ion cyclotron emission (ICE) offers a unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity PICE scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, nα/ni, of fusion born alpha particles confined within the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling for the first time. This resolves a long-standing question in the physics of fusion alpha-particle confinement and stability in magnetic confinement fusion plasmas. It confirms the magnetoacoustic cyclotron instability as the likely emission mechanism and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas.

Quantifying Fusion Born Ion Populations in Magnetically Confined Plasmas using Ion Cyclotron Emission.

PubMed

Carbajal, L; Dendy, R O; Chapman, S C; Cook, J W S

2017-03-10

Ion cyclotron emission (ICE) offers a unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity P_{ICE} scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, n_{α}/n_{i}, of fusion born alpha particles confined within the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling for the first time. This resolves a long-standing question in the physics of fusion alpha-particle confinement and stability in magnetic confinement fusion plasmas. It confirms the magnetoacoustic cyclotron instability as the likely emission mechanism and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas.

Dense plasma chemistry of hydrocarbons at conditions relevant to planetary interiors and inertial confinement fusion

NASA Astrophysics Data System (ADS)

Kraus, Dominik

2017-10-01

Carbon-hydrogen demixing and subsequent diamond precipitation has been predicted to strongly participate in shaping the internal structure and evolution of icy giant planets like Neptune and Uranus. The very same dense plasma chemistry is also a potential concern for CH plastic ablator materials in inertial confinement fusion (ICF) experiments where similar conditions are present during the first compression stage of the imploding capsule. Here, carbon-hydrogen demixing may enhance the hydrodynamic instabilities occurring in the following compression stages. First experiments applying dynamic compression and ultrafast in situ X-ray diffraction at SLAC's Linac Coherent Light Source demonstrated diamond formation from polystyrene (CH) at 150 GPa and 5000 K. Very recent experiments have now investigated the influence of oxygen, which is highly abundant in icy giant planets on the phase separation process. Compressing PET (C5H4O2) and PMMA(C5H8O2), we find again diamond formation at pressures above 150 GPa and temperatures of several thousand kelvins, showing no strong effect due to the presence of oxygen. Thus, diamond precipitation deep inside icy giant planets seems very likely. Moreover, small-angle X-ray scattering (SAXS) was added to the platform, which determines an upper limit for the diamond particle size, while the width of the diffraction features provides a lower limit. We find that diamond particles of several nanometers in size are formed on a nanosecond timescale. Finally, spectrally resolved X-ray scattering is used to scale amorphous diffraction signals and allows for determining the amount of carbon-hydrogen demixing inside the compressed samples even if no crystalline diamond is formed. This whole set of diagnostics provides unprecedented insights into the nanosecond kinetics of dense plasma chemistry.

Spherical torus fusion reactor

DOEpatents

Martin Peng, Y.K.M.

1985-10-03

The object of this invention is to provide a compact torus fusion reactor with dramatic simplification of plasma confinement design. Another object of this invention is to provide a compact torus fusion reactor with low magnetic field and small aspect ratio stable plasma confinement. In accordance with the principles of this invention there is provided a compact toroidal-type plasma confinement fusion reactor in which only the indispensable components inboard of a tokamak type of plasma confinement region, mainly a current conducting medium which carries electrical current for producing a toroidal magnet confinement field about the toroidal plasma region, are retained.

Direct-drive inertial confinement fusion: A review

NASA Astrophysics Data System (ADS)

Craxton, R. S.; Anderson, K. S.; Boehly, T. R.; Goncharov, V. N.; Harding, D. R.; Knauer, J. P.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Myatt, J. F.; Schmitt, A. J.; Sethian, J. D.; Short, R. W.; Skupsky, S.; Theobald, W.; Kruer, W. L.; Tanaka, K.; Betti, R.; Collins, T. J. B.; Delettrez, J. A.; Hu, S. X.; Marozas, J. A.; Maximov, A. V.; Michel, D. T.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Seka, W.; Solodov, A. A.; Soures, J. M.; Stoeckl, C.; Zuegel, J. D.

2015-11-01

The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser-plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon-decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive-ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

Control of a laser inertial confinement fusion-fission power plant

DOEpatents

Moses, Edward I.; Latkowski, Jeffery F.; Kramer, Kevin J.

2015-10-27

A laser inertial-confinement fusion-fission energy power plant is described. The fusion-fission hybrid system uses inertial confinement fusion to produce neutrons from a fusion reaction of deuterium and tritium. The fusion neutrons drive a sub-critical blanket of fissile or fertile fuel. A coolant circulated through the fuel extracts heat from the fuel that is used to generate electricity. The inertial confinement fusion reaction can be implemented using central hot spot or fast ignition fusion, and direct or indirect drive. The fusion neutrons result in ultra-deep burn-up of the fuel in the fission blanket, thus enabling the burning of nuclear waste. Fuels include depleted uranium, natural uranium, enriched uranium, spent nuclear fuel, thorium, and weapons grade plutonium. LIFE engines can meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the highly undesirable stockpiles of depleted uranium, spent nuclear fuel and excess weapons materials.

50 years of fusion research

NASA Astrophysics Data System (ADS)

Meade, Dale

2010-01-01

Fusion energy research began in the early 1950s as scientists worked to harness the awesome power of the atom for peaceful purposes. There was early optimism for a quick solution for fusion energy as there had been for fission. However, this was soon tempered by reality as the difficulty of producing and confining fusion fuel at temperatures of 100 million °C in the laboratory was appreciated. Fusion research has followed two main paths—inertial confinement fusion and magnetic confinement fusion. Over the past 50 years, there has been remarkable progress with both approaches, and now each has a solid technical foundation that has led to the construction of major facilities that are aimed at demonstrating fusion energy producing plasmas.

Reduction of time-averaged irradiation speckle nonuniformity in laser-driven plasmas due to target ablation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Epstein, R.

1997-09-01

In inertial confinement fusion (ICF) experiments, irradiation uniformity is improved by passing laser beams through distributed phase plates (DPPs), which produce focused intensity profiles with well-controlled, reproducible envelopes modulated by fine random speckle. [C. B. Burckhardt, Appl. Opt. {bold 9}, 695 (1970); Y. Kato and K. Mima, Appl. Phys. B {bold 29}, 186 (1982); Y. Kato {ital et al.}, Phys. Rev. Lett. {bold 53}, 1057 (1984); Laboratory for Laser Energetics LLE Review 33, NTIS Document No. DOE/DP/40200-65, 1987 (unpublished), p. 1; Laboratory for Laser Energetics LLE Review 63, NTIS Document No. DOE/SF/19460-91, 1995 (unpublished), p. 1.] A uniformly ablating plasmamore » atmosphere acts to reduce the contribution of the speckle to the time-averaged irradiation nonuniformity by causing the intensity distribution to move relative to the absorption layer of the plasma. This occurs most directly as the absorption layer in the plasma moves with the ablation-driven flow, but it is shown that the effect of the accumulating ablated plasma on the phase of the laser light also makes a quantitatively significant contribution. Analytical results are obtained using the paraxial approximation applied to the beam propagation, and a simple statistical model is assumed for the properties of DPPs. The reduction in the time-averaged spatial spectrum of the speckle due to these effects is shown to be quantitatively significant within time intervals characteristic of atmospheric hydrodynamics under typical ICF irradiation intensities. {copyright} {ital 1997 American Institute of Physics.}« less

First beryllium capsule implosions on the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kline, J. L.; Yi, S. A.; Simakov, A. N.

2016-05-15

The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm the superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since the 1990s, Be has been the preferred Inertial Confinement Fusion (ICF) ablator because of its higher mass ablation rate compared to that of carbon-based ablators. This enables ICF target designs with higher implosion velocities at lower radiation temperatures and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs measured the backscattered laser energy, capsule implosion velocity, core implosionmore » shape from self-emission, and in-flight capsule shape from backlit imaging. The laser backscatter is similar to that from comparable plastic (CH) targets under the same hohlraum conditions. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable to plastic ablators. The measured implosion shape indicates no significant reduction of laser energy from the inner laser cone beams reaching the hohlraum wall as compared with plastic and high-density carbon ablators. These results indicate that the high mass ablation rate for beryllium capsules does not significantly alter hohlraum energetics. In addition, these data, together with data for low fill-density hohlraum performance, indicate that laser power multipliers, required to reconcile simulations with experimental observations, are likely due to our limited understanding of the hohlraum rather than the capsule physics since similar multipliers are needed for both Be and CH capsules as seen in experiments.« less

COBRA accelerator for Sandia ICF diode research at Cornell University

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, D.L.; Ingwersen, P.; Bennett, L.F.

1995-05-01

The new COBRA accelerator is being built in stages at the Laboratory of Plasma Studies in Cornell University where its applications will include extraction diode and ion beam research in support of the light ion inertial confinement fusion (ICF) program at Sandia National Laboratories. The 4- to 5-MV, 125- to 250-kA accelerator is based on a four-cavity inductive voltage adder (IVA) design. It is a combination of new ferromagnetically-isolated cavities and self magnetically insulated transmission line (MITL) hardware and components from existing Sandia and Cornell facilities: Marx generator capacitors, hardware, and power supply from the DEMON facility; water pulse formingmore » lines (PFL) and gas switch from the Subsystem Test Facility (STF); a HERMES-III intermediate store capacitor (ISC); and a modified ion diode from Cornell`s LION. The present accelerator consists of a single modified cavity similar to those of the Sandia SABRE accelerator and will be used to establish an operating system for the first stage initial lower voltage testing. Four new cavities will be fabricated and delivered in the first half of FY96 to complete the COBRA accelerator. COBRA is unique in the sense that each cavity is driven by a single pulse forming line, and the IVA output polarity may be reversed by rotating the cavities 180{degrees} about their vertical axis. The site preparations, tank construction, and diode design and development are taking place at Cornell with growing enthusiasm as this machine becomes a reality. Preliminary results with the single cavity and short positive inner cylinder MITL configuration will soon be available.« less

First beryllium capsule implosions on the National Ignition Facility

DOE PAGES

Kline, J. L.; Yi, S. A.; Simakov, A. N.; ...

2016-05-01

The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm the superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since the 1990s, Be has been the preferred Inertial Confinement Fusion (ICF) ablator because of its higher mass ablation rate compared to that of carbon-based ablators. This enables ICF target designs with higher implosion velocities at lower radiation temperatures and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs measured the backscattered laser energy, capsule implosion velocity, core implosionmore » shape from self-emission, and in-flight capsule shape from backlit imaging. The laser backscatter is similar to that from comparable plastic (CH) targets under the same hohlraum conditions. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable to plastic ablators. The measured implosion shape indicates no significant reduction of laser energy from the inner laser cone beams reaching the hohlraum wall as compared with plastic and high-density carbon ablators. These results indicate that the high mass ablation rate for beryllium capsules does not significantly alter hohlraum energetics. In addition, these data, together with data for low fill-density hohlraum performance, indicate that laser power multipliers, required to reconcile simulations with experimental observations, are likely due to our limited understanding of the hohlraum rather than the capsule physics since similar multipliers are needed for both Be and CH capsules as seen in experiments.« less

Measurement of inflight shell areal density near peak velocity using a self backlighting technique

NASA Astrophysics Data System (ADS)

Pickworth, L. A.; Hammel, B. A.; Smalyuk, V. A.; MacPhee, A. G.; Scott, H. A.; Robey, H. F.; Landen, O. L.; Barrios, M. A.; Regan, S. P.; Schneider, M. B.; Hoppe, M., Jr.; Kohut, T.; Holunga, D.; Walters, C.; Haid, B.; Dayton, M.

2016-05-01

The growth of perturbations in inertial confinement fusion (ICF) capsules can lead to significant variation of inflight shell areal density (ρR), ultimately resulting in poor compression and ablator material mixing into the hotspot. As the capsule is accelerated inward, the perturbation growth results from the initial shock-transit through the shell and then amplification by Rayleigh-Taylor as the shell accelerates inwards. Measurements of ρR perturbations near peak implosion velocity (PV) are essential to our understanding of ICF implosions because they reflect the integrity of the capsule, after the inward acceleration growth is complete, of the actual shell perturbations including native capsule surface roughness and “isolated defects”. Quantitative measurements of shell-ρR perturbations in capsules near PV are challenging, requiring a new method with which to radiograph the shell. An innovative method, utilized in this paper, is to use the self-emission from the hotspot to “self- backlight” the shell inflight. However, with nominal capsule fills there is insufficient self-emission for this method until the capsule nears peak compression (PC). We produce a sufficiently bright continuum self-emission backlighter through the addition of a high-Z gas (∼ 1% Ar) to the capsule fill. This provides a significant (∼10x) increase in emission at hυ∼8 keV over nominal fills. “Self backlit” radiographs are obtained for times when the shock is rebounding from the capsule center, expanding out to meet the incoming shell, providing a means to sample the capsule optical density though only one side, as it converges through PV.

Experimental Observation of Nonlinear Mode Coupling In the Ablative Rayleigh-Taylor Instability on the NIF

NASA Astrophysics Data System (ADS)

Martinez, David

2015-11-01

We investigate on the National Ignition Facility (NIF) the ablative Rayleigh-Taylor (RT) instability in the transition from linear to highly nonlinear regimes. This work is part of the Discovery Science Program on NIF and of particular importance to indirect-drive inertial confinement fusion (ICF) where careful attention to the form of the rise to final peak drive is calculated to prevent the RT instability from shredding the ablator in-flight and leading to ablator mixing into the cold fuel. The growth of the ablative RT instability was investigated using a planar plastic foil with pre-imposed two-dimensional broadband modulations and diagnosed using x-ray radiography. The foil was accelerated for 12ns by the x-ray drive created in a gas-filled Au radiation cavity with a radiative temperature plateau at 175 eV. The dependence on initial conditions was investigated by systematically changing the modulation amplitude, ablator material and the modulation pattern. For each of these cases bubble mergers were observed and the nonlinear evolution of the RT instability showed insensitivity to the initial conditions. This experiment provides critical data needed to validate current theories on the ablative RT instability for indirect drive that relies on the ablative stabilization of short-scale modulations for ICF ignition. This paper will compare the experimental data to the current nonlinear theories. 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.

A revised analysis of Lawson criteria and its implications for ICF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panarella, E.

1995-12-31

Recently, a re-examination of the breakeven conditions for D-T plasmas has been presented. The results show that breakeven might not follow the Lawson nt rule, and in particular the plasma containment time seems to have lost the importance that it previously had. Moreover, a minimum particle density of the order of {approximately}10{sup 15} cm{sup {minus}3} has been found to be required for breakeven, which indicates that the inertial confinement fusion effort is in the right position to reach the fusion goal. In light of these results, a reassessment of Lawson`s analysis has been undertaken. Lawson considered the case of amore » pulsed system that followed this idealized cycle: the gas is heated instantaneously to a temperature T, which is maintained for a time t, after which the gas is allowed to cool. Conduction loss is neglected entirely, and the energy used to heat the gas and supply the radiation loss is regained as useful heat. In order to illustrate how the analysis by Lawson can be improved, the cycle to which the gas is subjected should be divided in three phases: 1st phase: rapid heating of the gas for a time t{sub 1} to bring it from the original ambient temperature to the fusion temperature T; 2nd phase: continuous injection of energy in the plasma for a time t{sub 2} to maintain the temperature T; 3rd phase: no more injection of energy and cooling of the gas to the ambient temperature in a time t{sub 3}.« less

Quantifying Fusion Born Ion Populations in Magnetically Confined Plasmas using Ion Cyclotron Emission

DOE PAGES

Carbajal, L.; Warwick Univ., Coventry; Dendy, R. O.; ...

2017-03-07

Ion cyclotron emission (ICE) offers unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity P ICE scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, n /n i , of fusion-born alpha-particles confined within the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling for the first time. This resolves a longstanding question in the physics of fusion alpha particle confinement and stability in MCF plasmas. It confirms the MCI as the likely emissionmore » mechanism and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas.« less

Direct-drive inertial confinement fusion: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Craxton, R. S.; Anderson, K. S.; Boehly, T. R.

The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermalmore » electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.« less

Direct-drive inertial confinement fusion: A review

DOE PAGES

Craxton, R. S.; Anderson, K. S.; Boehly, T. R.; ...

2015-11-25

In this study, the direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. Themore » problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 um—the third harmonic of the Nd:glass laser—and 0.248 um (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be non-local in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [C. A. Haynam et al., Appl. Opt. 46 (16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.« less

Direct-drive inertial confinement fusion: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Craxton, R. S.; Anderson, K. S.; Boehly, T. R.

In this study, the direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. Themore » problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 um—the third harmonic of the Nd:glass laser—and 0.248 um (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be non-local in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [C. A. Haynam et al., Appl. Opt. 46 (16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.« less

Simulations of Converging Shock Collisions for Shock Ignition

NASA Astrophysics Data System (ADS)

Sauppe, Joshua; Dodd, Evan; Loomis, Eric

2016-10-01

Shock ignition (SI) has been proposed as an alternative to achieving high gain in inertial confinement fusion (ICF) targets. A central hot spot below the ignition threshold is created by an initial compression pulse, and a second laser pulse drives a strong converging shock into the fuel. The collision between the rebounding shock from the compression pulse and the converging shock results in amplification of the converging shock and increases the hot spot pressure above the ignition threshold. We investigate shock collision in SI drive schemes for cylindrical targets with a polystyrene foam interior using radiation-hydrodynamics simulations with the RAGE code. The configuration is similar to previous targets fielded on the Omega laser. The CH interior results in a lower convergence ratio and the cylindrical geometry facilitates visualization of the shock transit using an axial X-ray backlighter, both of which are important for comparison to potential experimental measurements. One-dimensional simulations are used to determine shock timing, and the effects of low mode asymmetries in 2D computations are also quantified. LA-UR-16-24773.

A molecular dynamics approach to barrodiffusion

NASA Astrophysics Data System (ADS)

Cooley, James; Marciante, Mathieu; Murillo, Michael

2016-10-01

Unexpected phenomena in the reaction rates for Inertial Confinement Fusion (ICF) capsules have led to a renewed interest in the thermo-dynamically driven diffusion process for the past 10 years, often described collectively as barodiffusion. In the current context, barodiffusion would manifest as a process that separates ions of differing mass and charge ratios due to pressure and temperature gradients set-up through shock structures in the capsule core. Barrodiffusion includes additional mass transfer terms that account for the irreversible transport of species due to gradients in the system, both thermodynamic and electric e.g, i = - ρD [ ∇c +kp ∇ln(pi) +kT(i) ∇ln(Ti) +kt(e) ∇ln(Te) +eke/Ti ∇ϕ ] . Several groups have attacked this phenomena using continuum scale models and supplemented with kinetic theory to derive coefficients for the different diffusion terms based on assumptions about the collisional processes. In contrast, we have applied a molecular dynamics (MD) simulation to this system to gain a first-principle understanding of the rate kinetics and to assess the accuracy of the differin

Calibration of Fuji BAS-SR type imaging plate as high spatial resolution x-ray radiography recorder

NASA Astrophysics Data System (ADS)

Yan, Ji; Zheng, Jianhua; Zhang, Xing; Chen, Li; Wei, Minxi

2017-05-01

Image Plates as x-ray recorder have advantages including reusable, high dynamic range, large active area, and so on. In this work, Fuji BAS-SR type image plate combined with BAS-5000 scanner is calibrated. The fade rates of Image Plates has been measured using x-ray diffractometric in different room temperature; the spectral response of Image Plates has been measured using 241Am radioactive sealed source and fitting with linear model; the spatial resolution of Image Plates has been measured using micro-focus x-ray tube. The results show that Image Plates has an exponent decade curve and double absorption edge response curve. The spatial resolution of Image Plates with 25μ/50μ scanner resolution is 6.5lp/mm, 11.9lp/mm respectively and gold grid radiography is collected with 80lp/mm spatial resolution using SR-type Image Plates. BAS-SR type Image Plates can do high spatial resolution and quantitative radiographic works. It can be widely used in High energy density physics (HEDP), inertial confinement fusion (ICF) and laboratory astronomy physics.

Electroplating Gold-Silver Alloys for Spherical Capsules for NIF Double-Shell Targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhandarkar, N.; Horwood, C.; Bunn, T.

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 percentmore » 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.« less

Testing low-mode symmetry control with low-adiabat, extended pulse-lengths in BigFoot implosions on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Hohenberger, Matthias; Casey, D. T.; Thomas, C. A.; Baker, K. L.; Spears, B. K.; Khan, S. F.; Hurricane, O. A.; Callahan, D.

2017-10-01

The Bigfoot approach to indirect-drive inertial confinement fusion (ICF) has been developed as a compromise trading high-convergence and areal densities for high implosion velocities, large adiabats and hydrodynamic stability. Shape control and predictability are maintained by using relatively short laser pulses and merging the shocks within the DT-ice layer. These design choices ultimately limit the theoretically achievable performance, and one strategy to increase the 1-D performance is to reduce the shell adiabat by extending the pulse shape. However, this can result in loss of low-mode symmetry control, as the hohlraum ``bubble,'' the high-Z material launched by the outer-cone beams during the early part of the laser pulse, has more time to expand and will eventually intercept inner-cone beams preventing them from reaching the hohlraum waist, thus losing equatorial capsule drive. We report on experimental results exploring shape control and predictability with extended pulse shapes in BigFoot implosions. Prepared by LLNL under Contract DE-AC52-07NA27344.

The design of the optical Thomson scattering diagnostic for the National Ignition Facility.

PubMed

Datte, P S; Ross, J S; Froula, D H; Daub, K D; Galbraith, J; Glenzer, S; Hatch, B; Katz, J; Kilkenny, J; Landen, O; Manha, D; Manuel, A M; Molander, W; Montgomery, D; Moody, J; Swadling, G F; Weaver, J

2016-11-01

The National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community's understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot. A deep-UV probe beam (λ 0 -210 nm) will be used to optimize the scattered signal for plasma densities of 5 × 10 20 electrons/cm 3 while a 3ω probe will be used for experiments investigating lower density plasmas of 1 × 10 19 electrons/cm 3 . We report the phase I design of a two phase design strategy. Phase I includes the OTS telescope, spectrometer, and streak camera; these will be used to assess the background levels at NIF. Phase II will include the design and installation of a probe laser.

A high-speed two-frame, 1-2 ns gated X-ray CMOS imager used as a hohlraum diagnostic on the National Ignition Facility (invited).

PubMed

Chen, Hui; Palmer, N; Dayton, M; Carpenter, A; Schneider, M B; Bell, P M; Bradley, D K; Claus, L D; Fang, L; Hilsabeck, T; Hohenberger, M; Jones, O S; Kilkenny, J D; Kimmel, M W; Robertson, G; Rochau, G; Sanchez, M O; Stahoviak, J W; Trotter, D C; Porter, J L

2016-11-01

A novel x-ray imager, which takes time-resolved gated images along a single line-of-sight, has been successfully implemented at the National Ignition Facility (NIF). This Gated Laser Entrance Hole diagnostic, G-LEH, incorporates a high-speed multi-frame CMOS x-ray imager developed by Sandia National Laboratories to upgrade the existing Static X-ray Imager diagnostic at NIF. The new diagnostic is capable of capturing two laser-entrance-hole images per shot on its 1024 × 448 pixels photo-detector array, with integration times as short as 1.6 ns per frame. Since its implementation on NIF, the G-LEH diagnostic has successfully acquired images from various experimental campaigns, providing critical new information for understanding the hohlraum performance in inertial confinement fusion (ICF) experiments, such as the size of the laser entrance hole vs. time, the growth of the laser-heated gold plasma bubble, the change in brightness of inner beam spots due to time-varying cross beam energy transfer, and plasma instability growth near the hohlraum wall.

Helium Catalyzed D-D Fusion in a Levitated Dipole

NASA Astrophysics Data System (ADS)

Kesner, J.; Bromberg, L.; Garnier, D. T.; Hansen, A.; Mauel, M. E.

2003-10-01

Fusion research has focused on the goal of deuterium and tritium (D-T) fusion power because the reaction rate is large compared with the other fusion fuels: D-D or D-He3. Furthermore, the D-D cycle is difficult in traditional confinement devices, such as tokamaks, because good energy confinement is accompanied by good particle confinement which leads to an accumulation of ash. Fusion reactors based on the D-D reaction would be advantageous to D-T based reactors since they do not require the breeding of tritium and can reduce the flux of energetic neutrons that cause material damage. We propose a fusion power source based on the levitated dipole fusion concept that uses a "helium catalyzed D-D" fuel cycle, where rapid circulation of plasma allows the removal of tritium and the re-injection of the He3 decay product, eliminating the need for a massive blanket and shield. Stable dipole confinement derives from plasma compressibility instead of the magnetic shear and average good curvature. As a result, a dipole magnetic field can stabilize plasma at high beta while allowing large-scale adiabatic particle circulation. These properties may make the levitated dipole uniquely capable of achieving good energy confinement with low particle confinement. We find that a dipole based D-D power source can provide better utilization of magnetic field energy with a comparable mass power density to a D-T based tokamak power source.

Inertial-Electrostatic Confinement (IEC) Fusion for Space Propulsion

NASA Technical Reports Server (NTRS)

Nadler, Jon

1999-01-01

An Inertial-Electrostatic Confinement (IEC) device was assembled at the Marshall Space Flight Center (MSFC) Propulsion Research Center (PRC) to study the possibility of using EEC technology for deep space propulsion and power. Inertial-Electrostatic Confinement is capable of containing a nuclear fusion plasma in a series of virtual potential wells. These wells would substantially increase plasma confinement, possibly leading towards a high-gain, breakthrough fusion device. A one-foot in diameter IEC vessel was borrowed from the Fusion Studies Laboratory at the University of Illinois@Urbana-Champaign for the summer. This device was used in initial parameterization studies in order to design a larger, actively cooled device for permanent use at the PRC.

Inertial-Electrostatic Confinement (IEC) Fusion For Space Propulsion

NASA Technical Reports Server (NTRS)

Nadler, Jon

1999-01-01

An Inertial-Electrostatic Confinement (IEC) device was assembled at the Marshall Space Flight Center (MSFC) Propulsion Research Center (PRC) to study the possibility of using IEC technology for deep space propulsion and power. Inertial-Electrostatic Confinement is capable of containing a nuclear fusion plasma in a series of virtual potential wells. These wells would substantially increase plasma confinement, possibly leading towards a high-gain, breakthrough fusion device. A one-foot in diameter IEC vessel was borrowed from the Fusion Studies Laboratory at the University of Illinois @ Urbana-Champaign for the summer. This device was used in initial parameterization studies in order to design a larger, actively cooled device for permanent use at the PRC.

Theoretical z -pinch scaling relations for thermonuclear-fusion experiments.

PubMed

Stygar, W A; Cuneo, M E; Vesey, R A; Ives, H C; Mazarakis, M G; Chandler, G A; Fehl, D L; Leeper, R J; Matzen, M K; McDaniel, D H; McGurn, J S; McKenney, J L; Muron, D J; Olson, C L; Porter, J L; Ramirez, J J; Seamen, J F; Speas, C S; Spielman, R B; Struve, K W; Torres, J A; Waisman, E M; Wagoner, T C; Gilliland, T L

2005-08-01

We have developed wire-array z -pinch scaling relations for plasma-physics and inertial-confinement-fusion (ICF) experiments. The relations can be applied to the design of z -pinch accelerators for high-fusion-yield (approximately 0.4 GJ/shot) and inertial-fusion-energy (approximately 3 GJ/shot) research. We find that (delta(a)/delta(RT)) proportional (m/l)1/4 (Rgamma)(-1/2), where delta(a) is the imploding-sheath thickness of a wire-ablation-dominated pinch, delta(RT) is the sheath thickness of a Rayleigh-Taylor-dominated pinch, m is the total wire-array mass, l is the axial length of the array, R is the initial array radius, and gamma is a dimensionless functional of the shape of the current pulse that drives the pinch implosion. When the product Rgamma is held constant the sheath thickness is, at sufficiently large values of m/l, determined primarily by wire ablation. For an ablation-dominated pinch, we estimate that the peak radiated x-ray power P(r) proportional (I/tau(i))(3/2)Rlphigamma, where I is the peak pinch current, tau(i) is the pinch implosion time, and phi is a dimensionless functional of the current-pulse shape. This scaling relation is consistent with experiment when 13 MA < or = I < or = 20 MA, 93 ns < or = tau(i) < or = 169 ns, 10 mm < or = R < or = 20 mm, 10 mm < or = l < or = 20 mm, and 2.0 mg/cm < or = m/l < or = 7.3 mg/cm. Assuming an ablation-dominated pinch and that Rlphigamma is held constant, we find that the x-ray-power efficiency eta(x) congruent to P(r)/P(a) of a coupled pinch-accelerator system is proportional to (tau(i)P(r)(7/9 ))(-1), where P(a) is the peak accelerator power. The pinch current and accelerator power required to achieve a given value of P(r) are proportional to tau(i), and the requisite accelerator energy E(a) is proportional to tau2(i). These results suggest that the performance of an ablation-dominated pinch, and the efficiency of a coupled pinch-accelerator system, can be improved substantially by decreasing the implosion time tau(i). For an accelerator coupled to a double-pinch-driven hohlraum that drives the implosion of an ICF fuel capsule, we find that the accelerator power and energy required to achieve high-yield fusion scale as tau(i)0.36 and tau(i)1.36, respectively. Thus the accelerator requirements decrease as the implosion time is decreased. However, the x-ray-power and thermonuclear-yield efficiencies of such a coupled system increase with tau(i). We also find that increasing the anode-cathode gap of the pinch from 2 to 4 mm increases the requisite values of P(a) and E(a) by as much as a factor of 2.

Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager

DOE PAGES

Nagayama, T.; Mancini, R. C.; Mayes, D.; ...

2015-11-18

Temperature and density asymmetry diagnosis is critical to advance inertial confinement fusion (ICF) science. A multi-monochromatic x-ray imager (MMI) is an attractive diagnostic for this purpose. The MMI records the spectral signature from an ICF implosion core with time resolution, 2-D space resolution, and spectral resolution. While narrow-band images and 2-D space-resolved spectra from the MMI data constrain temperature and density spatial structure of the core, the accuracy of the images and spectra depends not only on the quality of the MMI data but also on the reliability of the post-processing tools. In this paper, we synthetically quantify the accuracymore » of images and spectra reconstructed from MMI data. Errors in the reconstructed images are less than a few percent when the space-resolution effect is applied to the modeled images. The errors in the reconstructed 2-D space-resolved spectra are also less than a few percent except those for the peripheral regions. Spectra reconstructed for the peripheral regions have slightly but systematically lower intensities by ~6% due to the instrumental spatial-resolution effects. However, this does not alter the relative line ratios and widths and thus does not affect the temperature and density diagnostics. We also investigate the impact of the pinhole size variation on the extracted images and spectra. A 10% pinhole size variation could introduce spatial bias to the images and spectra of ~10%. A correction algorithm is developed, and it successfully reduces the errors to a few percent. Finally, it is desirable to perform similar synthetic investigations to fully understand the reliability and limitations of each MMI application.« less

Investigation of thickness uniformity of thin metal films by using α-particle energy loss method and successive scanning measurements

NASA Astrophysics Data System (ADS)

Li, Gang; Xu, Jiayun; Bai, Lixin

2017-03-01

The metal films are widely used in the Inertial Confinement Fusion (ICF) experiments to obtain the radiation opacity, and the accuracy of the measuring results mainly depends on the accuracy of the film thickness and thickness uniformity. The traditional used measuring methods all have various disadvantages, the optical method and stylus method cannot provide mass thickness which reflects the internal density distribution of the films, and the weighing method cannot provide the uniformity of the thickness distribution. This paper describes a new method which combines the α-particle energy loss (AEL) method and the successive scanning measurements to obtain the film thickness and thickness uniformity. The measuring system was partly installed in the vacuum chamber, and the relationship of chamber pressure and energy loss caused by the residual air in the vacuum chamber was studied for the source-to-detector distance ranging from 1 to 5 cm. The results show that the chamber pressure should be less than 10 Pa for the present measuring system. In the process of measurement, the energy spectrum of α-particles transmitted through each different measuring point were obtained, and then recorded automatically by a self-developed multi-channel analysis software. At the same time, the central channel numbers of the spectrum (CH) were also saved in a text form document. In order to realize the automation of data processing and represent the thickness uniformity visually in a graphic 3D plot, a software package was developed to convert the CH values into film thickness and thickness uniformity. The results obtained in this paper make the film thickness uniformity measurements more accurate and efficient in the ICF experiments.

Radiation-driven hydrodynamics of long pulse hohlraums on the National Ignition Facility*,**

NASA Astrophysics Data System (ADS)

Dewald, Eduard

2005-10-01

The first hohlraum experiments have been performed at the National Ignition Facility (NIF) in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics. Vacuum hohlraums have been irradiated with laser powers up to 8 TW, 1-9 ns pulse lengths and energies up to 17 kJ to activate several hohlraum drive diagnostics, to study the radiation temperature scaling with the laser power and hohlraum size, and to make contact with hohlraum experiments performed at the NOVA and Omega laser facilities. The vacuum hohlraums yield low laser backscattering and hot electron fractions, and the hohlraum radiation temperature measured with a newly activated 18 channel Dante soft x-ray power diagnostic agrees well with two-dimensional LASNEX calculations. Using the unique feature of NIF to deliver long steady laser drives, these hohlraum experiments have also validated analytical models and LASNEX calculations of hohlraum plasma filling as evidenced by time-resolved hard x-ray imaging and coronal hohlraum radiation production measured by Dante. Analytical modeling used to estimate hohlraum radiation limits due to plasma filling is in agreement with measurements and predicts for full NIF system with peak powers up to 500 TW peak radiation temperatures that are considerably higher than required in ICF designs. * Work performed in collaboration with L.J. Suter, O.L. Landen, J. Schein, K. Campbell, M.S. Schneider, J. Holder, S.H. Glenzer, J.W. McDonald, C. Niemann, A.J. Mackinnon, D.H. Kalantar, C. Haynam, S. Dixit **This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.

In search of late time evolution self-similar scaling laws of Rayleigh-Taylor and Richtmyer-Meshkov hydrodynamic instabilities - recent theorical advance and NIF Discovery-Science experiments

NASA Astrophysics Data System (ADS)

Shvarts, Dov

2017-10-01

Hydrodynamic instabilities, and the mixing that they cause, are of crucial importance in describing many phenomena, from very large scales such as stellar explosions (supernovae) to very small scales, such as inertial confinement fusion (ICF) implosions. Such mixing causes the ejection of stellar core material in supernovae, and impedes attempts at ICF ignition. The Rayleigh-Taylor instability (RTI) occurs at an accelerated interface between two fluids with the lower density accelerating the higher density fluid. The Richtmyer-Meshkov (RM) instability occurs when a shock wave passes an interface between the two fluids of different density. In the RTI, buoyancy causes ``bubbles'' of the light fluid to rise through (penetrate) the denser fluid, while ``spikes'' of the heavy fluid sink through (penetrate) the lighter fluid. With realistic multi-mode initial conditions, in the deep nonlinear regime, the mixing zone width, H, and its internal structure, progress through an inverse cascade of spatial scales, reaching an asymptotic self-similar evolution: hRT =αRT Agt2 for RT and hRM =αRM tθ for RM. While this characteristic behavior has been known for years, the self-similar parameters αRT and θRM and their dependence on dimensionality and density ratio have continued to be intensively studied and a relatively wide distribution of those values have emerged. This talk will describe recent theoretical advances in the description of this turbulent mixing evolution that sheds light on the spread in αRT and θRM. Results of new and specially designed experiments, done by scientists from several laboratories, were performed recently using NIF, the only facility that is powerful enough to reach the self-similar regime, for quantitative testing of this theoretical advance, will be presented.

Measurements of ion species separation in strong plasma shocks

NASA Astrophysics Data System (ADS)

Rinderknecht, Hans

2017-10-01

Shocks are important dynamic phenomena in inertial confinement fusion (ICF) and astrophysical plasmas. While the relationship between upstream and downstream plasmas far from the shock front is fully determined by conservation equations, the structure of shock fronts is determined by dynamic kinetic processes. Kinetic theory and simulations predict that the width of a strong (M >2) collisional plasma shock front is on the order of tens of ion mean-free-paths. The shock front structure plays an important role for overall dynamics when the shock front width approaches plasma scale lengths, as in the spherically converging shock in the DT-vapor in an ICF implosion. However, there has been no experimental data benchmarking shock front structure in the plasma phase. The structure of a shock front in a plasma with multiple ion species has been directly measured for the first time using a combination of Thomson scattering and proton radiography in experiments on the OMEGA laser. Thomson scattering of a 263.25 nm probe beam is used to diagnose electron density, electron and ion temperature, ion species concentration, and flow velocity in strong shocks (M 5) propagating through low-density (ρ 0.1 mg/cc) plasmas composed of H(98%) +Ne(2%). Within the shock front, velocity separation of the ion species is observed for the first time: the light species (H) accelerates to of order the shocked fluid velocity (450 microns/ns) before the heavy species (Ne) begins to move. This velocity-space separation implies that the separation of ion species occurs at the shock front, a predicted feature of shocks in multi-species plasmas but never observed experimentally until now. Comparison of experimental data with PIC, Vlasov-Fokker-Planck, and multi-component hydrodynamic simulations will be presented.

Hydrodynamic Instabilities in High-Energy-Density Settings

NASA Astrophysics Data System (ADS)

Smalyuk, Vladimir

2016-10-01

Our understanding of hydrodynamic instabilities, such as the Rayleigh-Taylor (RT), Richtmyer-Meshkov (RM), and Kelvin-Helmholtz (KH) instabilities, in high-energy-density (HED) settings over past two decades has progressed enormously. The range of conditions where hydrodynamic instabilities are experimentally observed now includes direct and indirect drive inertial confinement fusion (ICF) where surprises continue to emerge, linear and nonlinear regimes, classical interfaces vs. stabilized ablation fronts, tenuous ideal plasmas vs. high density Fermi degenerate plasmas, bulk fluid interpenetration vs. mixing down to the atomic level, in the presence of magnetic fields and/or intense radiation, and in solid state plastic flow at high pressures and strain rates. Regimes in ICF can involve extreme conditions of matter with temperatures up to kilovolts, densities of a thousand times solid densities, and time scales of nanoseconds. On the other hand, scaled conditions can be generated that map to exploding stars (supernovae) with length and time scales of millions of kilometers and hours to days or even years of instability evolution, planetary formation dynamics involving solid-state plastic flow which severely modifies the RT growth and continues to challenge reliable theoretical descriptions. This review will look broadly at progress in probing and understanding hydrodynamic instabilities in these very diverse HED settings, and then will examine a few cases in more depth to illustrate the detailed science involved. Experimental results on large-scale HED facilities such as the Omega, Nike, Gekko, and Shenguang lasers will be reviewed and the latest developments at the National Ignition Facility (NIF) and Z machine will be covered. Finally, current overarching questions and challenges will be summarized to motivate research directions for future. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagayama, T.; Mancini, R. C.; Mayes, D.

2015-11-15

Temperature and density asymmetry diagnosis is critical to advance inertial confinement fusion (ICF) science. A multi-monochromatic x-ray imager (MMI) is an attractive diagnostic for this purpose. The MMI records the spectral signature from an ICF implosion core with time resolution, 2-D space resolution, and spectral resolution. While narrow-band images and 2-D space-resolved spectra from the MMI data constrain temperature and density spatial structure of the core, the accuracy of the images and spectra depends not only on the quality of the MMI data but also on the reliability of the post-processing tools. Here, we synthetically quantify the accuracy of imagesmore » and spectra reconstructed from MMI data. Errors in the reconstructed images are less than a few percent when the space-resolution effect is applied to the modeled images. The errors in the reconstructed 2-D space-resolved spectra are also less than a few percent except those for the peripheral regions. Spectra reconstructed for the peripheral regions have slightly but systematically lower intensities by ∼6% due to the instrumental spatial-resolution effects. However, this does not alter the relative line ratios and widths and thus does not affect the temperature and density diagnostics. We also investigate the impact of the pinhole size variation on the extracted images and spectra. A 10% pinhole size variation could introduce spatial bias to the images and spectra of ∼10%. A correction algorithm is developed, and it successfully reduces the errors to a few percent. It is desirable to perform similar synthetic investigations to fully understand the reliability and limitations of each MMI application.« less

Understanding reliability and some limitations of the images and spectra reconstructed from a multi-monochromatic x-ray imager.

PubMed

Nagayama, T; Mancini, R C; Mayes, D; Tommasini, R; Florido, R

2015-11-01

Temperature and density asymmetry diagnosis is critical to advance inertial confinement fusion (ICF) science. A multi-monochromatic x-ray imager (MMI) is an attractive diagnostic for this purpose. The MMI records the spectral signature from an ICF implosion core with time resolution, 2-D space resolution, and spectral resolution. While narrow-band images and 2-D space-resolved spectra from the MMI data constrain temperature and density spatial structure of the core, the accuracy of the images and spectra depends not only on the quality of the MMI data but also on the reliability of the post-processing tools. Here, we synthetically quantify the accuracy of images and spectra reconstructed from MMI data. Errors in the reconstructed images are less than a few percent when the space-resolution effect is applied to the modeled images. The errors in the reconstructed 2-D space-resolved spectra are also less than a few percent except those for the peripheral regions. Spectra reconstructed for the peripheral regions have slightly but systematically lower intensities by ∼6% due to the instrumental spatial-resolution effects. However, this does not alter the relative line ratios and widths and thus does not affect the temperature and density diagnostics. We also investigate the impact of the pinhole size variation on the extracted images and spectra. A 10% pinhole size variation could introduce spatial bias to the images and spectra of ∼10%. A correction algorithm is developed, and it successfully reduces the errors to a few percent. It is desirable to perform similar synthetic investigations to fully understand the reliability and limitations of each MMI application.

Foam shell cryogenic ICF target

DOEpatents

Darling, Dale H.

1987-01-01

A uniform cryogenic layer of DT fuel is maintained in a fusion target having a low density, small pore size, low Z rigid foam shell saturated with liquid DT fuel. Capillary action prevents gravitational slumping of the fuel layer. The saturated shell may be cooled to produce a solid fuel layer.

BOOK REVIEW: Inertial confinement fusion: The quest for ignition and energy gain using indirect drive

NASA Astrophysics Data System (ADS)

Yamanaka, C.

1999-06-01

Inertial confinement fusion (ICF) is an alternative way to control fusion which is based on scaling down a thermonuclear explosion to a small size, applicable for power production, a kind of thermonuclear internal combustion engine. This book extends many interesting topics concerning the research and development on ICF of the last 25 years. It provides a systematic development of the physics basis and also various experimental data on radiation driven implosion. This is a landmark treatise presented at the right time. It is based on the article ``Development of the indirect-drive approach to inertial confinement fusion and the target physics basis for ignition and gain'' by J.D. Lindl, published in Physics of Plasmas, Vol. 2, November 1995, pp. 3933-4024. As is well known, in the United States of America research on the target physics basis for indirect drive remained largely classified until 1994. The indirect drive approaches were closely related to nuclear weapons research at Lawrence Livermore and Los Alamos National Laboratories. In Japan and other countries, inertial confinement fusion research for civil energy has been successfully performed to achieve DT fuel pellet compression up to 1000 times normal density, and indirect drive concepts, such as the `Cannon Ball' scheme, also prevailed at several international conferences. In these circumstances the international fusion community proposed the Madrid Manifesto in 1988, which urged openness of ICF information to promote international collaboration on civil energy research for the future resources of the human race. This proposal was also supported by some of the US scientists. The United States Department of Energy revised its classification guidelines for ICF six years after the Madrid Manifesto. This first book from the USA treating target physics issues, covering topics from implosion dynamics to hydrodynamic stability, ignition physics, high-gain target design and the scope for energy applications is enthusiastically welcomed. The author joined Lawrence Livermore National Laboratory in 1972 to perform intensive theoretical and computational research on implosion and ignition. He was awarded the Edward Teller Medal in 1993. One therefore expects the topics to be treated with authority, and this expectation is well fulfilled. The general treatment throughout the book is to begin with the basic physics of implosion and show how its development leads to an explanation of many fundamental ideas about implosion, via direct drive or indirect drive, particularly ideas associated with radiation transport. This approach is generally successful, with the reader immediately able to relate the theoretical treatments to physical problems. One danger in this approach, however, is that fundamental concepts in implosion often become stressed within the framework of indirect radiation drive of hohlraum targets oriented towards research in the National Ignition Facility. The references in this book to Livermore or Los Alamos internal documents are not yet publicly available, because many are in the process of review for declassification. The reader will have to become accustomed to this situation, which has lasted for a long time but now seems to be gradually improving. The treatise is composed of 13 chapters, including 271 illustrations. An overview of ICF and the historical development of indirect drive in the ICF programme are described in Chapters 1 and 2. Direct drive and indirect drive have different features. The choice of which to use is a very interesting issue. The former has a higher laser-target coupling efficiency but is less uniform in laser irradiation due to discrete beams of lasers. Beam smoothing techniques have a key role in direct drive. The indirect drive by soft X rays which are generated at the inner surface of a hohlraum can have a higher uniform irradiation to reduce the growth of perturbations due to Rayleigh-Taylor (RT) instabilities. The soft X ray drive has much higher ablation rates and is less sensitive to hot electron preheat. A potential disadvantage of indirect drive is the larger scale length of the plasma travelled by the laser beam from the inlet hole to the hohlraum wall. Parametric instabilities in hohlraums have problems because of energy loss and coupling. One of the most important issues for indirect drive is a radiation drive concept which is essentially independent of the driver, such as laser or particle beam. The historical progress of ICF in the USA mainly depended upon the resolution of the fusion database for weaponry. This was a reason to choose indirect drive as the main scheme. Several structures of hohlraum target are described which for a long time were closed to the public. As the minimum energy for ignition depends strongly on the achievable implosion velocity, a great deal of benefit is derived from operating at the highest possible hohlraum temperature and in-flight aspect ratio (IFAR). The conclusion of Chapters 3, 4 and 5 is that achieving an implosion velocity of 3 × 107cm/s with an IFAR-30 Fermi degenerated shell would require a minimum drive temperature of about 200 eV. The hydrodynamic instability, ignition threshold and capsule gain are discussed in Chapter 6. The RT hydrodynamic instability began at the upper limit of the IFAR and hence at the peak implosion velocity. The growth rate of the instability in the acceleration phase was found to be suppressed by the ablation flow at Osaka. Instability during the deceleration phase was primarily stabilized by electron conduction. The combined effects of acceleration, feed-through and deceleration show that the principal modes contributing to perturbations in the fuel have spherical harmonic mode numbers less than about 30-40. The higher modes are rapidly reduced by rarefaction. The lower modes are killed by so-called `fire polishing'. The target uniformity and irradiation uniformity are very effective at suppressing instabilities. The maximum number of e-foldings sets the upper limit of the implosion velocity. This gives the threshold energy of ignition. The minimum capsule energy for ignition for indirect drive is compared with Nuckoll's projections for direct drive. The estimation depends strongly upon the effects of hydrodynamic instability and symmetry in the compressed fuel volume. If the margin of energy is 2, the necessary capsule absorbed energy is about 90 kJ with a radiation temperature of 300 eV. The coupling between driver and capsule is 10-15%, and the driver energy is 0.6-0.9 MJ. The scaling laws for the capsule absorbed power, radius and pulse length with a certain IFAR are given. It is concluded (Chapter 6) that the optimum strategy for gain is operation at the minimum implosion velocity consistent with the desired capsule size and yield, because at the excess implosion velocity the capsules tend to ignite earlier than the optimal point in the compression process. The most crucial issues for the hohlraum target are the coupling efficiency and hohlraum radiation uniformity. Various kinds of devices for hohlraum structures and double cone irradiation schemes have been investigated. These technological developments are energetically described. The implosion symmetry reproducibility (Chapters 7 and 8) for the Precision Nova advanced system meets the requirement of 1% uniformity for ignition experiment time averaged flux. Combined tests of symmetry and hydrodynamic instability as well as the hohlraum plasma conditions estimating the simulated Brillouin scattering (SBS) and simulated Raman scattering (SRS) effects and their influence on the hot electron preheat are summarized in Chapters 9, 10 and 11. The tolerable fraction of hot electrons for keeping the DT fuel preheat at approximately the Fermi specific energy indicates that direct drive capsules are 3 to 4 times larger than the indirect drive capsules. As a conclusion, Chapters 12 and 13 are proudly devoted to the National Ignition Facility and ignition targets. The NIF has a 192 beam, frequency tripled Nd:glass laser system with routine target energies and powers of 1.8 MJ and 500 TW, appropriately pulse shaped. The 192 beams are clustered in groups of 4, so that there are effectively 8 spots in each of the inner cones, and 16 in the outer cones in the hohlraum. Each cluster of 4 beams combines to form an effective f/8 optic. Various kinds of target design are described, for instance, a baseline design 300 eV hohlraum capsule, which absorbs 1.35 MJ of light, an ignition point hydrocarbon (CH) capsule, which is aimed at determining the requirements for symmetry, stability and ignition, and a lower temperature 250 eV capsule with a beryllium ablator, which provides a trade-off between hydroinstabilities and laser-plasma effects. The NIF baseline capsule designs absorb 150 kJ, of which about 25 kJ ends up in the compressed fuel. The central temperature increases to 10 keV when the capsule produces 400 kJ. The fuel energy gain is about 16 at ignition, or when the alpha particle deposition is about 3 times the initial energy delivered to the compressed fuel. The NIF baseline targets are then expected to yield up to 15 MJ and a fuel gain of about 600. Estimates based on NOVA experiments and modelling indicate that SBS, SRS and other plasma hazard processes can be kept within acceptable limits. If these are not attained, the ultimate recourse is to increase the hohlraum size, reduce the laser intensity and reduce the drive temperature to that of the 250 eV design, which has significantly less plasma. The remaining uncertainties can be mitigated by changes in the target design. The author has confidence ignition will be achieved in NIF, which seems to be strongly supported by the Centurion-Halite underground nuclear experiments demonstrating the excellent performance and the basic feasibility of achieving high gain. He thoughtfully adds a comment that developments in direct drive have reached the point where this approach also looks quite promising. NIF will be able to shift rapidly ( <= 1 d) between indirect drive and direct drive. Finally, the short last chapter (Chapter 13) gives an overview on the greatest potential for future ICF power plants. In a book review, questions are usually asked about the readers the book is primarily intended for, whether the book is written at the appropriate level for those readers and whether there are other books that achieve similar objectives. The last section of the Preface states that this book provides an in-depth analysis of theoretical and experimental work on indirect drive ICF classified up to 1994, as well as work carried out throughout the world. It is intended to serve as a reference guide for researchers in the field. Each topic covered contains enough introductory material that the book can also be used at the graduate level by students or newly interested researchers. Most of the laser technology and diagnostic development are not covered at all. To this reviewer that statement is a succinct summary of what the book achieves. Working fusion physicists, particularly in ICF, will find the book to be both instructive and enjoyable. As a secondary market, the book could well be used as a text for a graduate course in laser plasma physics, although some parts are like review papers. As to which books cover some of the same material, W.L. Kruer published Physics of Laser Plasma Interactions (Addison-Wesley, Redwood City, CA, 1988), which is suitable as a textbook for graduate students and also for the plasma physicist in general and C. Yamanaka published Introduction to Laser Fusion (Harwood Academic, Chur, 1991), which is the only book treating implosion physics, lasers, target design and diagnostics prior to the USDOE's declassification. As for the Handbook of Plasma Physics series (edited by M.N. Rosenbluth and R.Z. Sagdeev), Vol. 3, Physics of Laser Plasma (edited by A.H. Rubenchik and S. Witkowski) (Elsevier Science, Amsterdam, 1991) comes to mind. However, this last book is larger, and covers somewhat diverse topics. The typography of the book presently under review is also much to be preferred. In summary, I would strongly recommend the book by Lindl to my colleagues in plasma physics, particularly to those engaged in ICF.

Thermonuclear Fusion: An Energy Source for the Future

ERIC Educational Resources Information Center

Drummond, William E.

1973-01-01

Discusses current research in thermonuclear fusion with particular emphasis on the problem of confining hot plasma. Recent experiments indicate that magnetic bottles called tokamaks may achieve the necessary confinement times, and this break-through has given renewed optimism to the feasibility of commercial fusion power by the turn of the…

Inertial-confinement fusion with lasers

NASA Astrophysics Data System (ADS)

Betti, R.; Hurricane, O. A.

2016-05-01

The quest for controlled fusion energy has been ongoing for over a half century. The demonstration of ignition and energy gain from thermonuclear fuels in the laboratory has been a major goal of fusion research for decades. Thermonuclear ignition is widely considered a milestone in the development of fusion energy, as well as a major scientific achievement with important applications in national security and basic sciences. The US is arguably the world leader in the inertial confinement approach to fusion and has invested in large facilities to pursue it, with the objective of establishing the science related to the safety and reliability of the stockpile of nuclear weapons. Although significant progress has been made in recent years, major challenges still remain in the quest for thermonuclear ignition via laser fusion. Here, we review the current state of the art in inertial confinement fusion research and describe the underlying physical principles.

EDITORIAL: Inertial Fusion State of the Art---A Collection of Overview and Technical Papers from IFSA2003

NASA Astrophysics Data System (ADS)

Hogan, W. J.

2004-12-01

The Third International Conference on Inertial Fusion Sciences and Applications (IFSA2003) was held in Monterey, CA, USA, on 7--12 September 2003. The goal of IFSA2003 was to bring together scientists and engineers in the fields of inertial fusion sciences, high energy density physics, inertial fusion energy (IFE) and other related research and applications. By all measures IFSA2003 was a resounding success. IFSA2003 was hosted by the University of California, which was supported in organizing the conference by seven institutions: General Atomics, Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, Los Alamos National Laboratory, Naval Research Laboratory, Sandia National Laboratory and the University of Rochester, Laboratory for Laser Energetics. IFSA2003 was the largest IFSA conference yet with 405 participants from 17 countries. Approximately 430 papers were presented and 236 appeared in the Proceedings, published in July 2004 by the American Nuclear Society [1]. A subset of the Nuclear Fusion Board of Editors, those who work on inertial confinement fusion (ICF), recommended creating this special issue of Nuclear Fusion by selecting a representative cross-section of the papers presented at IFSA2003. Authors of the selected papers were asked to expand their papers and make them suitable for publication in it Nuclear Fusion. Nineteen papers are presented in this special issue. They represent a cross-section of the papers presented at IFSA2003. However, there was no attempt to represent the `feel' of the conference by having the same fraction of papers on each topic as existed at IFSA. There were far more detailed scientific papers at IFSA than are presented in this special issue. However, in the interest of giving the reader a cross-section of the papers and showing the entire breadth of ICF research going on, we have biased the selection process toward review papers. The first three papers here are based upon the keynote talks at IFSA2003 and are, therefore, overviews of all ICF research being done in the Americas, Asia, and Europe. The next two papers are also reviews but of a different sort. The Teller Medal is awarded at the IFSA conferences for pioneering work and leadership in inertial fusion and high energy density science. The two recipients for 2003 were H. Takabe of the Institute of Laser Engineering at Osaka University and L. Suter of Lawrence Livermore National Laboratory. These awardees were asked to deliver the two Teller Lectures at IFSA based upon the work for which they were being honoured. The papers presented here are expansions of those two review talks. Suter chose to focus his review on his recent work on ignition physics for targets driven by 0.54 m light. This is of interest because large facilities like the National Ignition Facility (NIF) will deliver much more energy in the frequency doubled wavelength than in the frequency tripled one. Takabe, on the other hand chose to give a historical perspective of his lifelong work. The other 14 papers were selected to represent a cross-section of the research being conducted in the science and engineering of inertial fusion. The papers by Haan et al and Holstein et al represent some of the recent progress in target design calculations for the ignition first experiments. Haan presents his team's work on indirect drive ignition targets (driven by 0.35 m) intended for the National Ignition Facility (NIF) when all the beamlines are activated. Holstein does the same for targets being design for the Laser MegaJoule (LMJ). Suter's paper, presented earlier as a Teller Lecture also falls into this ignition target physics category. The next four papers look at some of the exciting high energy density physics being studied in ICF facilities around the world. Glenzer et al looks at stimulated light scattering processes in hot dense plasmas. Pukhov et al look at relativistic laser-plasma interactions that produce energetic particles and x-rays. Peyrusse et al examine atomic physics and radiative processes in hot dense plasmas. Koenig et al examine ways to simulate planetary physics processes using high pressures generated in laser driven shocks. Non-laser approaches to inertial fusion were also fully represented at IFSA2003. The paper by Lebedev et al shows important physics developments in Z-pinch plasmas. Sharp et al present chamber transport modelling for heavy ion fusion drivers. Technology development studies were also well represented at IFSA2003. There was a special session on facility and driver developments that contained several papers. Presented here are the papers by Miller et al on the NIF, Danson et al on the Vulcan petawatt facility, and Myers et al on KrF lasers for IFE. A paper by Goodin et al shows progress in finding cost effective target manufacturing methods for IFE. Finally, there were many papers at IFSA2003 that focused upon the very promising but more immature field of fast ignition. Barty et al give an overview of the development issues for short pulse lasers that will be essential if fast ignition is to become mainstream. A paper by Kodama et al looks at target physics using cone focus targets. Fast ignition lasers and innovative target physics within this concept were a `hot topic' at IFSA2003. The IFSA conferences have become the principal forum for the exchange of research results in inertial fusion and high energy and density science. There is a unique blend of science and technology. All fields of inertial fusion are represented. This special issue is a snapshot and a cross-section of the field at this time. We hope the reader is encouraged to look into more of the papers in areas that interest them. References [1] Inertial Fusion Sciences and Applications: State of the Art 2003 ed B. Hammel, D. Meyerhofer, J. Meyer-ter-Vehn and H. Azechi American Nuclear Society (July 2004) These IFSA2003 proceedings may be purchased on-line at http://www.ans.org.

HEDP and new directions for fusion energy

NASA Astrophysics Data System (ADS)

Kirkpatrick, Ronald C.

2010-06-01

Magnetic-confinement fusion energy and inertia-confinement fusion energy (IFE) represent two extreme approaches to the quest for the application of thermonuclear fusion to electrical energy generation. Blind pursuit of these extreme approaches has long delayed the achievement of their common goal. We point out the possibility of an intermediate approach that promises cheaper, and consequently more rapid development of fusion energy. For example, magneto-inertial fusion appears to be possible over a broad range of parameter space. It is further argued that imposition of artificial constraints impedes the discovery of physics solutions for the fusion energy problem.

The kinetic stabilizer: a route to simpler tandem mirror systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, R F

2001-02-02

As we enter the new millennium there is a growing urgency to address the issue of finding long-range solutions to the world's energy needs. Fusion offers such a solution, provided economically viable means can be found to extract useful energy from fusion reactions. While the magnetic confinement approach to fusion has a long and productive history, to date the mainline approaches to magnetic confinement, namely closed systems such as the tokamak, appear to many as being too large and complex to be acceptable economically, despite the impressive progress that has made toward the achievement of fusion-relevant confinement parameters. Thus theremore » is a growing feeling that it is imperative to search for new and simpler approaches to magnetic fusion, ones that might lead to smaller and more economically attractive fusion power plants.« less

High-Energy Electron Confinement in a Magnetic Cusp Configuration

NASA Astrophysics Data System (ADS)

Park, Jaeyoung; Krall, Nicholas A.; Sieck, Paul E.; Offermann, Dustin T.; Skillicorn, Michael; Sanchez, Andrew; Davis, Kevin; Alderson, Eric; Lapenta, Giovanni

2015-04-01

We report experimental results validating the concept that plasma confinement is enhanced in a magnetic cusp configuration when β (plasma pressure/magnetic field pressure) is of order unity. This enhancement is required for a fusion power reactor based on cusp confinement to be feasible. The magnetic cusp configuration possesses a critical advantage: the plasma is stable to large scale perturbations. However, early work indicated that plasma loss rates in a reactor based on a cusp configuration were too large for net power production. Grad and others theorized that at high β a sharp boundary would form between the plasma and the magnetic field, leading to substantially smaller loss rates. While not able to confirm the details of Grad's work, the current experiment does validate, for the first time, the conjecture that confinement is substantially improved at high β . This represents critical progress toward an understanding of the plasma dynamics in a high-β cusp system. We hope that these results will stimulate a renewed interest in the cusp configuration as a fusion confinement candidate. In addition, the enhanced high-energy electron confinement resolves a key impediment to progress of the Polywell fusion concept, which combines a high-β cusp configuration with electrostatic fusion for a compact, power-producing nuclear fusion reactor.

Inertial confinement fusion for energy: overview of the ongoing experimental, theoretical and numerical studies

NASA Astrophysics Data System (ADS)

Jacquemot, S.

2017-10-01

This paper provides an overview of the results presented at the 26th IAEA Fusion Energy Conference in the field of inertial confinement fusion for energy, covering its various experimental, numerical/theoretical and technological facets, as well as the different paths towards ignition that are currently followed worldwide.

Status of fusion research and implications for D/He-3 systems

NASA Technical Reports Server (NTRS)

Miley, George H.

1988-01-01

World wide programs in both magnetic confinement and inertial confinement fusion research have made steady progress towards the experimental demonstration of energy breakeven. However, after breakeven is achieved, considerable time and effort must still be expended to develop a usable power plant. The main program described is focused on Deuterium-Tritium devices. In magnetic confinement, three of the most promising high beta approaches with a reasonable experimental data base are the Field Reversed Configuration, the high field tokamak, and the dense Z-pinch. The situation is less clear in inertial confinement where the first step requires an experimental demonstration of D/T spark ignition. It appears that fusion research has reached a point in time where an R and D plan to develop a D/He-3 fusion reactor can be laid out with some confidence of success.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carbajal, L.; Warwick Univ., Coventry; Dendy, R. O.

Ion cyclotron emission (ICE) offers unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity P ICE scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, n /n i , of fusion-born alpha-particles confined within the plasma. We present fully nonlinear self-consistent kinetic simulations that reproduce this scaling for the first time. This resolves a longstanding question in the physics of fusion alpha particle confinement and stability in MCF plasmas. It confirms the MCI as the likely emissionmore » mechanism and greatly strengthens the basis for diagnostic exploitation of ICE in future burning plasmas.« less

Measuring spatial distributions of nuclear burn in ICF implosions at OMEGA and the NIF using proton emission imaging

NASA Astrophysics Data System (ADS)

Seguin, Fredrick; Rinderknecht, H. G.; Zylstra, A.; Sio, H.; Frenje, J.; Li, C. K.; Petrasso, R.; Rosenberg, M.; Marshall, F. J.; Sangster, T. C.; McKenty, P.; Craxton, S.; Rygg, J. R.; Le Pape, S.; Smalyuk, V.; Amendt, P. A.; Wilks, S. C.; MacKinnon, A.; Hoffman, N. M.

2015-11-01

Fusion reactions in ICF implosions of D3He-filled capsules produce 14.7-MeV D3He protons and 3-MeV DD protons. Spatial distributions of the D3He and DD reactions are studied with a penumbral imaging camera that utilizes a CR-39-based imaging detector to detect the protons. Up to three orthogonal cameras have been used simultaneously at OMEGA to study the 3-D structure of asymmetric implosions, and two orthogonal cameras have now been used to study an exploding-pusher implosion at the NIF. Recent data from OMEGA and from the NIF will be shown. This work was supported in part by NLUF, US DOE, and LLE.

Hard X-ray and Particle Beams Research on 1.7 MA Z-pinch and Laser Plasma Experiments

NASA Astrophysics Data System (ADS)

Shrestha, Ishor; Kantsyrev, Victor; Safronova, Alla; Esaulov, Andrey; Nishio, Mineyuki; Shlyaptseva, Veronica; Keim, Steven; Weller, Michael; Stafford, Austin; Petkov, Emil; Schultz, Kimberly; Cooper, Matthew; PPDL Team

2013-10-01

Studies of hard x-ray (HXR) emission, electron and ion beam generation in z-pinch and laser plasmas are important for Inertial Confinement Fusion (ICF) and development of HXR sources from K-shell and L-shell radiation. The characteristics of HXR and particle beams produced by implosions of planar wire arrays, nested and single cylindrical wire arrays, and X-pinches were analyzed on 100 ns UNR Zebra generator with current up to 1.7 MA. In addition, the comparison of characteristics of HXR and electron beams on Zebra and 350 fs UNR Leopard laser experiments with foils has been performed. The diagnostics include Faraday cups, HXR diodes, different x-ray spectrometers and imaging systems, and ion mass spectrometer using the technique of Thomson parabola. Future work on HXRs and particle beams in HED plasmas is discussed. This work was supported by the DOE/NNSA Cooperative agreement DE-NA0001984 and in part by DE-FC52-06NA27616. This work was also supported by the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-13-1-0033, to University of Nevada, Reno.

Hot spot mix in ICF implosions on the NIF

NASA Astrophysics Data System (ADS)

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.

Heating a plasma by a broadband stream of fast electrons: Fast ignition, shock ignition, and Gbar shock wave applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gus’kov, S. Yu., E-mail: guskov@sci.lebedev.ru; Nicolai, Ph.; Ribeyre, X.

2015-09-15

An exact analytic solution is found for the steady-state distribution function of fast electrons with an arbitrary initial spectrum irradiating a planar low-Z plasma with an arbitrary density distribution. The solution is applied to study the heating of a material by fast electrons of different spectra such as a monoenergetic spectrum, a step-like distribution in a given energy range, and a Maxwellian spectrum, which is inherent in laser-produced fast electrons. The heating of shock- and fast-ignited precompressed inertial confinement fusion (ICF) targets as well as the heating of a target designed to generate a Gbar shock wave for equation ofmore » state (EOS) experiments by laser-produced fast electrons with a Maxwellian spectrum is investigated. A relation is established between the energies of two groups of Maxwellian fast electrons, which are responsible for generation of a shock wave and heating the upstream material (preheating). The minimum energy of the fast and shock igniting beams as well as of the beam for a Gbar shock wave generation increases with the spectral width of the electron distribution.« less

National Ignition Facility project acquisition plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Callaghan, R.W.

The purpose of this National Ignition Facility Acquisition Plan is to describe the overall procurement strategy planned for the National Ignition Facility (NIF) Project. The scope of the plan describes the procurement activities and acquisition strategy for the following phases of the NIF Project, each of which receives either plant and capital equipment (PACE) or other project cost (OPC) funds: Title 1 and 2 design and Title 3 engineering (PACE); Optics manufacturing facilitization and pilot production (OPC); Convention facility construction (PACE); Procurement, installation, and acceptance testing of equipment (PACE); and Start-up (OPC). Activities that are part of the base Inertialmore » Confinement Fusion (ICF) Program are not included in this plan. The University of California (UC), operating Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory, and Lockheed-Martin, which operates Sandia National Laboratory (SNL) and the University of Rochester Laboratory for Laser Energetics (UR-LLE), will conduct the acquisition of needed products and services in support of their assigned responsibilities within the NIF Project structure in accordance with their prime contracts with the Department of Energy (DOE). LLNL, designated as the lead Laboratory, will have responsibility for all procurements required for construction, installation, activation, and startup of the NIF.« less

Study on the temperature gradient evolution of large size nonlinear crystal based on the fluid-solid coupling theory

NASA Astrophysics Data System (ADS)

Sun, F. Z.; Zhang, P.; Liang, Y. C.; Lu, L. H.

2014-09-01

In the non-critical phase-matching (NCPM) along the Θ =90° direction, ADP and DKDP crystals which have many advantages, including a large effective nonlinear optical coefficient, a small PM angular sensitivity and non beam walk-off, at the non-critical phase-matching become the competitive candidates in the inertial confinement fusion(ICF) facility, so the reasonable temperature control of crystals has become more and more important .In this paper, the fluid-solid coupling models of ADP crystal and DKDP crystal which both have anisotropic thermal conductivity in the states of vacuum and non-vacuum were established firstly, and then simulated using the fluid analysis software Fluent. The results through the analysis show that the crystal surface temperature distribution is a ring shape, the temperature gradients in the direction of the optical axis both the crystals are 0.02°C and 0.01°C due to the air, the lowest temperature points of the crystals are both at the center of surface, and the temperatures are lower than 0.09°C and 0.05°C compared in the vacuum and non-vacuum environment, then propose two designs for heating apparatus.

Self characterization of a coded aperture array for neutron source imaging

DOE PAGES

Volegov, P. L.; Danly, C. R.; Fittinghoff, D. N.; ...

2014-12-15

The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning DT plasma during the stagnation stage of ICF implosions. Since the neutron source is small (~100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be preciselymore » aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.« less

Laser-driven formation of a high-pressure phase in amorphous silica.

PubMed

Salleo, Alberto; Taylor, Seth T; Martin, Michael C; Panero, Wendy R; Jeanloz, Raymond; Sands, Timothy; Génin, François Y

2003-12-01

Because of its simple composition, vast availability in pure form and ease of processing, vitreous silica is often used as a model to study the physics of amorphous solids. Research in amorphous silica is also motivated by its ubiquity in modern technology, a prominent example being as bulk material in transmissive and diffractive optics for high-power laser applications such as inertial confinement fusion (ICF). In these applications, stability under high-fluence laser irradiation is a key requirement, with optical breakdown occurring when the fluence of the beam is higher than the laser-induced damage threshold (LIDT) of the material. The optical strength of polished fused silica transmissive optics is limited by their surface LIDT. Surface optical breakdown is accompanied by densification, formation of point defects, cratering, material ejection, melting and cracking. Through a combination of electron diffraction and infrared reflectance measurements we show here that synthetic vitreous silica transforms partially into a defective form of the high-pressure stishovite phase under high-intensity (GW cm(-2)) laser irradiation. This phase transformation offers one suitable mechanism by which laser-induced damage grows catastrophically once initiated, thereby dramatically shortening the service lifetime of optics used for high-power photonics.

A novel hybrid algorithm for the design of the phase diffractive optical elements for beam shaping

NASA Astrophysics Data System (ADS)

Jiang, Wenbo; Wang, Jun; Dong, Xiucheng

2013-02-01

In this paper, a novel hybrid algorithm for the design of a phase diffractive optical elements (PDOE) is proposed. It combines the genetic algorithm (GA) with the transformable scale BFGS (Broyden, Fletcher, Goldfarb, Shanno) algorithm, the penalty function was used in the cost function definition. The novel hybrid algorithm has the global merits of the genetic algorithm as well as the local improvement capabilities of the transformable scale BFGS algorithm. We designed the PDOE using the conventional simulated annealing algorithm and the novel hybrid algorithm. To compare the performance of two algorithms, three indexes of the diffractive efficiency, uniformity error and the signal-to-noise ratio are considered in numerical simulation. The results show that the novel hybrid algorithm has good convergence property and good stability. As an application example, the PDOE was used for the Gaussian beam shaping; high diffractive efficiency, low uniformity error and high signal-to-noise were obtained. The PDOE can be used for high quality beam shaping such as inertial confinement fusion (ICF), excimer laser lithography, fiber coupling laser diode array, laser welding, etc. It shows wide application value.

Experiments to measure ablative Richtmyer-Meshkov growth of Gaussian bumps in plastic capsules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loomis, Eric; Batha, Steve; Sedillo, Tom

2010-06-02

Growth of hydrodynamic instabilities at the interfaces of inertial confinement fusion capsules (ICF) due to ablator and fuel non-uniformities have been of primary concern to the ICF program since its inception. To achieve thermonuclear ignition at Megajoule class laser systems such as the NIF, targets must be designed for high implosion velocities, which requires higher in-flight aspect ratios (IFAR) and diminished shell stability. Controlling capsule perturbations is thus of the utmost importance. Recent simulations have shown that features on the outer surface of an ICF capsule as small as 10 microns wide and 100's of nanometers tall such as bumps,more » divots, or even dust particles can profoundly impact capsule performance by leading to material jetting or mix into the hotspot. Recent x-ray images of implosions on the NIF may be evidence of such mixing. Unfortunately, our ability to accurately predict these effects is uncertain due to disagreement between equation of state (EOS) models. In light of this, we have begun a campaign to measure the growth of isolated defects (Gaussian bumps) due to ablative Richtmyer-Meshkov in CH capsules to validate these models. The platform that has been developed uses halfraums with radiation temperatures near 75 eV (Rev. 4 foot-level) driven by 15-20 beams from the Omega laser (Laboratory for Laser Energetics, University of Rochester, NY), which sends a ~2.5 Mbar shock into a planar CH foil. Gaussian-shaped bumps (20 microns wide, 4-7 microns tall) are deposited onto the ablation side of the target. On-axis radiography with a saran (Cl He α - 2.8 keV) backlighter is used to measure bump evolution prior to shock breakout. Shock speed measurements will also be made with Omega's active shock breakout (ASBO) and streaked optical pyrometery (SOP) diagnostics in conjunction with filtered x-ray photodiode arrays (DANTE) to determine drive conditions in the target. These data will be used to discriminate between EOS models so that one may be selected to design the shape and intensity of the foot in an ignition-level drive pulse so that bump amplitude is minimized by the time the shell begins to accelerate.« less

Comparison between initial Magnetized Liner Inertial Fusion experiments and integrated simulations

NASA Astrophysics Data System (ADS)

Sefkow, A. B.; Gomez, M. R.; Geissel, M.; Hahn, K. D.; Hansen, S. B.; Harding, E. C.; Peterson, K. J.; Slutz, S. A.; Koning, J. M.; Marinak, M. M.

2014-10-01

The Magnetized Liner Inertial Fusion (MagLIF) approach to ICF has obtained thermonuclear fusion yields using the Z facility. Integrated magnetohydrodynamic simulations provided the design for the first neutron-producing experiments using capabilities that presently exist, and the initial experiments measured stagnation radii rstag < 75 μm, temperatures around 3 keV, and isotropic neutron yields up to YnDD = 2 ×1012 from imploded liners reaching peak velocities around 70 km/s over an implosion time of about 60 ns. We present comparisons between the experimental observables and post-shot degraded integrated simulations. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Incomplete mass transfer processes in 28Si +93Nb reaction

NASA Astrophysics Data System (ADS)

Tripathi, R.; Sodaye, S.; Ramachandran, K.; Sharma, S. K.; Pujari, P. K.

Cross sections of reaction products were measured in 28Si +93Nb reaction using recoil catcher technique involving by off-line gamma-ray spectrometry at beam energies of 105 and 155MeV. At Elab = 155MeV, the contribution from different incomplete mass transfer processes is investigated. Results of the present studies show the contribution from deep inelastic collision (DIC), massive transfer or incomplete fusion (ICF) and quasi-elastic transfer (QET). The contribution from massive transfer reactions was confirmed from the fractional yield of the reaction products in the forward catcher foil. The present results are different from those from the reactions with comparatively higher entrance channel mass asymmetry with lighter projectiles, for which dominant transfer processes are ICF and QET which involve mass transfer predominantly from projectile to target. The N/Z values of the products close to the target mass were observed to be in a wide range, starting from N/Z of the target (93Nb) and extending slightly below the N/Z of the composite system, consistent with the contribution from DIC and QET reactions. At Elab = 105MeV, a small contribution from QET was observed in addition to complete fusion.

EDITORIAL: Message from the Editor

NASA Astrophysics Data System (ADS)

Schüller, F. C.

2005-01-01

The group of 25 articles published in this special issue of Nuclear Fusion aims to monitor the progress made with experiments on fusion physics that have been conducted worldwide up to the end of 2004. These articles are based on overview reports from the various experimental teams presented at the Fusion Energy Conference (FEC 2004). This conference was organized by the IAEA together with the Portuguese host organization CFN-IST and was held in Vilamoura, Portugal, in early November 2004. The overviews presented at the conference have been rewritten and extended for the purpose of this special issue and submitted to the standard double-referee peer-review of Nuclear Fusion. Most teams have made use of this opportunity. Therefore this issue, which also includes four conference summaries, presents a reasonably complete picture of the progress made since FEC 2002 in Lyon. The articles are placed in the following sequence: Conference summaries Theory of magnetic confinement Experimental confinement, plasma-material interactions and innovative concepts Experiments on stability, energetic particles, waves and current drive Inertial confinement fusion Tokamaks Performance: JT-60U, JET, DIII-D, ASDEX-U, C-MOD Steady state/long pulse operation: Tore Supra, HT-7, TRIAM Spherical tokamaks: MAST, NSTX Tritium experiments: JET Diagnostics and heating methods: JET (diagnostics), T-10 (ECRH and diagnostics) and FTU (LHH + ECRH) New devices: HL-2A Small devices Alternative magnetic confinement concepts Stellarators: LHD, TJ-II Reversed field pinches: MST Inertial confinement Direct drive Heavy ion beam fusion Readers will also notice the supplementary issue of the journal (volume 45, issue 10A). This extra issue contains the 15-year overview report on progress in fusion research as written by the International Fusion Research Council (IFRC) under the editorial responsibility of the IFRC. Both issues together will give the interested reader a state-of-the-art picture of the progress in nuclear fusion research.

The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, A.; Betti, R.; Shvarts, D.

To achieve ignition with inertial confinement fusion (ICF), it is important to under- stand the effect of asymmetries on the hydrodynamics and energetics of the compres- sion. This paper describes a theoretical model for the compression of distorted hot spots, and quantitative estimates using hydrodynamic simulations. The asymmetries are categorized into low (Ι < 6) and intermediate (Ι < A < 40) modes by comparison of the wavelength with the thermal-diffusion scale length. Long-wavelength modes introduce substantial nonradial motion, whereas intermediate-wavelength modes in- volve more cooling by thermal ablation. We discover that for distorted hot spots, the measured neutron-averaged propertiesmore » can be very different from the real hydro- dynamic conditions. This is because mass ablation driven my thermal conduction introduces flows in the Rayleigh–Taylor bubbles, this results in pressure variation, in addition to temperature variation between the bubbles and the neutron-producing region (~1 keV for intermediate modes). The differences are less pronounced for long-wavelength asymmetries since the bubbles are relatively hot and sustain fusion reactions. The yield degradation$-$ with respect to the symmetric$-$ results primarily from a reduction in the hot-spot pressure for low modes and from a reduction in burn volume for intermediate modes. It is shown that the degradation in internal energy of the hot-spot is equivalent for both categories, and is equal to the total residual energy in the shell including the bubbles. This quantity is correlated with the shell residual kinetic energy for low-modes, and includes the kinetic energy in the bubbles for mid-modes.« less

The physics of long- and intermediate-wavelength asymmetries of the hot spot: Compression hydrodynamics and energetics

DOE PAGES

Bose, A.; Betti, R.; Shvarts, D.; ...

2017-10-03

To achieve ignition with inertial confinement fusion (ICF), it is important to under- stand the effect of asymmetries on the hydrodynamics and energetics of the compres- sion. This paper describes a theoretical model for the compression of distorted hot spots, and quantitative estimates using hydrodynamic simulations. The asymmetries are categorized into low (Ι < 6) and intermediate (Ι < A < 40) modes by comparison of the wavelength with the thermal-diffusion scale length. Long-wavelength modes introduce substantial nonradial motion, whereas intermediate-wavelength modes in- volve more cooling by thermal ablation. We discover that for distorted hot spots, the measured neutron-averaged propertiesmore » can be very different from the real hydro- dynamic conditions. This is because mass ablation driven my thermal conduction introduces flows in the Rayleigh–Taylor bubbles, this results in pressure variation, in addition to temperature variation between the bubbles and the neutron-producing region (~1 keV for intermediate modes). The differences are less pronounced for long-wavelength asymmetries since the bubbles are relatively hot and sustain fusion reactions. The yield degradation$-$ with respect to the symmetric$-$ results primarily from a reduction in the hot-spot pressure for low modes and from a reduction in burn volume for intermediate modes. It is shown that the degradation in internal energy of the hot-spot is equivalent for both categories, and is equal to the total residual energy in the shell including the bubbles. This quantity is correlated with the shell residual kinetic energy for low-modes, and includes the kinetic energy in the bubbles for mid-modes.« less

Control of plasma stored energy for burn control using DIII-D in-vessel coils

DOE PAGES

Hawryluk, Richard J.; Eidietis, Nicholas W.; Grierson, Brian A.; ...

2015-04-09

A new approach has been experimentally demonstrated to control the stored energy by applying a non-axisymmetric magnetic field using the DIII-D in-vessel coils to modify the energy confinement time. In future burning plasma experiments as well as magnetic fusion energy power plants, various concepts have been proposed to control the fusion power. The fusion power in a power plant operating at high gain can be related to the plasma stored energy and hence, is a strong function of the energy confinement time. Thus, an actuator that modifies the confinement time can be used to adjust the fusion power. In relativelymore » low collisionality DIII-D discharges, the application of nonaxisymmetric magnetic fields results in a decrease in confinement time and density pumpout. Furthermore, gas puffing was used to compensate the density pumpout in the pedestal while control of the stored energy was demonstrated by the application of non-axisymmetric fields.« less

Using a Z-pinch precursor plasma to produce a cylindrical, hotspot ignition, ICF

NASA Astrophysics Data System (ADS)

Chittenden, Jeremy

2005-10-01

We show that if the same precursor plasma that exists in metal wire arrays can be generated with a Deuterium-Tritium plasma then this precursor provides an ideal target for a cylindrical magneto-inertial ICF scheme. The precursor is generated from a fraction of the mass of the array which arrives on the axis early in time and remains confined at high density by the inertia of further material bombarding the axis. Later on, the main implosion of the DT Z-pinch produces a dense, low temperature shell which compressively heats the precursor target to high temperatures and tamps its expansion. The azimuthal magnetic field in the hotspot is sufficient to reduce the Larmor radius for the alpha particles to much less than the hotspot size, which dramatically reduces the ρR required for ignition. A computational analysis of this approach is presented, including a study of the thermonuclear burn wave propagation. The robustness of the scheme with respect to instabilities, confinement time and drive parameters is examined. The results indicate that a high energy gain can be achieved using Z-pinches with 50-100 MA currents and a few hundred nanosecond rise-times. This work was partially supported by the U.S. Department of Energy through cooperative agreement DE-FC03-02NA00057.

Laboratory Study of the Shaping and Evolution of Magnetized Episodic Plasma Jets

NASA Astrophysics Data System (ADS)

Higginson, Drew

2015-11-01

The expansion of hot, dense plasma (100 eV, 1018 cm-3) into vacuum occupied by a strong magnetic field (β =Pkinetic /Pmag ~ 1) along the expansion axis is a seemingly elementary physics problem, yet it is one that has scarcely been investigated. As well as being a fundamental problem in plasma physics, understanding such a situation is important to provide an explanation of large-scale jets observed in the formation of young stellar objects (YSO). Additionally, the ability to manipulate such a situation (e.g. to optimize x-ray emission) may be essential to the feasibility of recently proposed inertial confinement fusion (ICF) schemes with an imposed magnetic field. To investigate these situations, a CF2 foil is irradiated with the ELFIE laser (1013 W/cm2, 0.6 ns) in an external axial magnetic field of 20 T. As the plasma expands radially it is restricted by magnetic pressure that creates a cavity with a shock at the expansion edge. This shock redirects flow back on axis and creates a strong, stationary, conical shock that collimates the flow into a jet traveling over 1000 km/s and extending many centimeters. The effect of episodic heating (e.g. from variable mass ejection in a YSO, or pulse shaping in ICF) was investigated by irradiating the target with a precursor laser (1012 W/cm2, 0.6 ns) at 9 to 19 ns prior to the main pulse. The addition of this relatively small addition of energy (<20% of the main pulse energy) changed the dynamics of the expansion dramatically by increasing the strength of the conical shock, reducing the forward expansion of the cavity and dramatically increasing emission. We also present MHD simulations that reproduce the experimental observables and help to understand dynamics of jet and cavity formation. Prepared by LLNL under Contract DE-AC52-07NA27344. Presently at Lawrence Livermore National Laboratory.

Lithium ion beam divergence on SABRE extraction ion diode experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, D.L.; Cuneo, M.E.; Johnson, D.J.

Intense lithium beams are of particular interest for light ion inertial confinement fusion applications because lithium ions can be accelerated at high voltage in a single charge state (Li{sup +}) with a high mass-to-charge ratio and appropriate range for efficient focusing and heating of a hohlraum ICF target. Scaling to ion power densities adequate to drive high gain pellet implosions (600 TW at 30 MeV) will require a large number of beams transported, temporally bunched, and focused onto a target, with the necessary target standoff to ensure survival of the driver modules. For efficient long distance transport and focusing tomore » a small pellet, lithium beam divergence must be reduced to about 12 mrad or less (depending on the transport scheme). To support the eventual development of a light ion driver module for ICF applications, the authors are currently working to improve the composition, uniformity, and divergence of lithium ion beams produced by both passive LiF and active laser-generated lithium ion sources on extraction applied-B ion diodes on the SABRE accelerator (1 TW, 5 MV, 250 kA). While lithium beam divergence accounting and control are an essential goal of these experiments, divergence measurements for lithium beams present some unique problems not encountered to the same degree in divergence measurements on proton sources. To avoid these difficulties, the authors have developed a large aperture ion imaging diagnostic for time-resolved lithium divergence measurements. The authors will report on the operation of this lithium beam divergence diagnostic and on results of time-resolved divergence measurements in progress for passive LiF ion sources and laser-produced active lithium sources operated in diode configurations designed to control divergence growth. Comparisons will also be made with time-integrated divergence results obtained with small entrance aperture ultracompact pinhole cameras.« less

The Physics Basis of ITER Confinement

NASA Astrophysics Data System (ADS)

Wagner, F.

2009-02-01

ITER will be the first fusion reactor and the 50 year old dream of fusion scientists will become reality. The quality of magnetic confinement will decide about the success of ITER, directly in the form of the confinement time and indirectly because it decides about the plasma parameters and the fluxes, which cross the separatrix and have to be handled externally by technical means. This lecture portrays some of the basic principles which govern plasma confinement, uses dimensionless scaling to set the limits for the predictions for ITER, an approach which also shows the limitations of the predictions, and describes briefly the major characteristics and physics behind the H-mode—the preferred confinement regime of ITER.

Inertial Confinement Fusion quarterly report, January-March 1998, volume 8, number 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruer, W

1998-03-31

The coupling of laser light with plasmas is one of the key physics issues for the use of high-power lasers for inertial fusion, high-energy-density physics, and scientific stockpile stewardship. The coupling physics is extremely rich and challenging, particularly in the large plasmas to be accessed on the National Ignition Facility (NIF). The coupling mechanisms span the gamut from classical inverse bremsstrahlung absorption to a variety of nonlinear optical processes. These include stimulated Raman scattering (SRS) from electron plasma waves, stimulated Brillouin scattering (SBS) from ion sound waves, resonant decay into electron plasma and ion sound waves, and laser beam filamentation.more » These processes depend on laser intensity and produce effects such as changes in the efficiency and location of the energy deposition or generation of a component of very energetic electrons, which can preheat capsules. Coupling physics issues have an extremely high leverage. The coupling models are clearly very important ingredients for detailed calculations of laser-irradiated target behavior. Improved understanding and models enable a more efficient use of laser facilities, which becomes even more important as these facilities become larger and more expensive. Advances in the understanding also allow a more timely and cost-effective identification of new applications of high-power lasers, such as for generation of high-temperature hohlraums and compact x-ray sources, or for discovery of advanced fusion schemes. Finally, the interaction of intense electromagnetic waves with ionized media is a fundamental topic of interest to numerous areas of applied science and is an excellent test bed for advancing plasma science and computational modeling of complex phenomena. This issue of the ICF Quarterly Report is dedicated to laser--plasma interactions. The eight articles present a cross section of the broad progress in understanding the key interaction issues, such as laser beam bending, spraying, and scattering, as well as scaling the Nova results to NIF.« less

Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donovan, D. C.; Boris, D. R.; Kulcinski, G. L.

2013-03-15

A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies inmore » a high voltage ({approx}100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device.« less

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

NASA Astrophysics Data System (ADS)

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.

Zonal flow generation in inertial confinement fusion implosions

DOE PAGES

Peterson, J. L.; Humbird, K. D.; Field, J. E.; ...

2017-03-06

A supervised machine learning algorithm trained on a multi-petabyte dataset of inertial confinement fusion simulations has identified a class of implosions that robustly achieve high yield, even in the presence of drive variations and hydrodynamic perturbations. These implosions are purposefully driven with a time-varying asymmetry, such that coherent flow generation during hotspot stagnation forces the capsule to self-organize into an ovoid, a shape that appears to be more resilient to shell perturbations than spherical designs. Here this new class of implosions, whose configurations are reminiscent of zonal flows in magnetic fusion devices, may offer a path to robust inertial fusion.

Diagnosing magnetized liner inertial fusion experiments on Z

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, Stephanie B.; Gomez, Matthew R.; Sefkow, Adam B.

The Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (~10 12 DD neutrons) from multi-keV deuterium plasmasinertially confined by slow (~10 cm/μs), stable, cylindrical implosions. Moreover, effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 10 10. Further analysis of extensive power, imaging, and spectroscopicx-ray measurements provides a detailed picture of ~3 keV temperatures, 0.3 g/cm 3 densities, gradients, and mix in the fuel and liner over the 1–2 ns stagnation duration.

Zonal flow generation in inertial confinement fusion implosions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peterson, J. L.; Humbird, K. D.; Field, J. E.

A supervised machine learning algorithm trained on a multi-petabyte dataset of inertial confinement fusion simulations has identified a class of implosions that robustly achieve high yield, even in the presence of drive variations and hydrodynamic perturbations. These implosions are purposefully driven with a time-varying asymmetry, such that coherent flow generation during hotspot stagnation forces the capsule to self-organize into an ovoid, a shape that appears to be more resilient to shell perturbations than spherical designs. Here this new class of implosions, whose configurations are reminiscent of zonal flows in magnetic fusion devices, may offer a path to robust inertial fusion.

Diagnosing magnetized liner inertial fusion experiments on Z

DOE PAGES

Hansen, Stephanie B.; Gomez, Matthew R.; Sefkow, Adam B.; ...

2015-05-14

The Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (~10 12 DD neutrons) from multi-keV deuterium plasmasinertially confined by slow (~10 cm/μs), stable, cylindrical implosions. Moreover, effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 10 10. Further analysis of extensive power, imaging, and spectroscopicx-ray measurements provides a detailed picture of ~3 keV temperatures, 0.3 g/cm 3 densities, gradients, and mix in the fuel and liner over the 1–2 ns stagnation duration.

System and method for generating steady state confining current for a toroidal plasma fusion reactor

DOEpatents

Fisch, Nathaniel J.

1981-01-01

A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave RF energy is injected into said plasma to establish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected RF energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected RF energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range .DELTA.. The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width .DELTA. in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated in the plasma.

System and method for generating steady state confining current for a toroidal plasma fusion reactor

DOEpatents

Bers, Abraham

1981-01-01

A system for generating steady state confining current for a toroidal plasma fusion reactor providing steady-state generation of the thermonuclear power. A dense, hot toroidal plasma is initially prepared with a confining magnetic field with toroidal and poloidal components. Continuous wave RF energy is injected into said plasma to estalish a spectrum of traveling waves in the plasma, where the traveling waves have momentum components substantially either all parallel, or all anti-parallel to the confining magnetic field. The injected RF energy is phased to couple to said traveling waves with both a phase velocity component and a wave momentum component in the direction of the plasma traveling wave components. The injected RF energy has a predetermined spectrum selected so that said traveling waves couple to plasma electrons having velocities in a predetermined range .DELTA.. The velocities in the range are substantially greater than the thermal electron velocity of the plasma. In addition, the range is sufficiently broad to produce a raised plateau having width .DELTA. in the plasma electron velocity distribution so that the plateau electrons provide steady-state current to generate a poloidal magnetic field component sufficient for confining the plasma. In steady state operation of the fusion reactor, the fusion power density in the plasma exceeds the power dissipated inthe plasma.

The design of the optical Thomson scattering diagnostic for the National Ignition Facility [The preliminary design of the optical Thomson scattering diagnostic for the National Ignition Facility

DOE PAGES

Datte, P. S.; Ross, J. S.; Froula, D. H.; ...

2016-09-21

Here, the National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community’s understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot. A deep-UV probe beam (λ 0-210 nm) will be used to optimize the scatteredmore » signal for plasma densities of 5 × 10 20 electrons/cm 3 while a 3ω probe will be used for experiments investigating lower density plasmas of 1 × 10 19 electrons/cm 3. We report the phase I design of a two phase design strategy. Phase I includes the OTS telescope, spectrometer, and streak camera; these will be used to assess the background levels at NIF. Phase II will include the design and installation of a probe laser.« less

Vorticity dynamics after the shock–turbulence interaction

DOE PAGES

Livescu, Daniel; Ryu, Jaiyoung

2015-07-23

In this article, the interaction of a shock wave with quasi-vortical isotropic turbulence (IT) represents a basic problem for studying some of the phenomena associated with high speed flows, such as hypersonic flight, supersonic combustion and Inertial Confinement Fusion (ICF). In general, in practical applications, the shock width is much smaller than the turbulence scales and the upstream turbulent Mach number is modest. In this case, recent high resolution shock-resolved Direct Numerical Simulations (DNS) (Ryu and Livescu, J Fluid Mech 756, R1, 2014) show that the interaction can be described by the Linear Interaction Approximation (LIA). Using LIA to alleviatemore » the need to resolve the shock, DNS post-shock data can be generated at much higher Reynolds numbers than previously possible. Here, such results with Taylor Reynolds number approximately 180 are used to investigate the changes in the vortical structure as a function of the shock Mach number, M s, up to M s = 10. It is shown that, as M s increases, the shock interaction induces a tendency towards a local axisymmetric state perpendicular to the shock front, which has a profound influence on the vortex-stretching mechanism and divergence of the Lamb vector and, ultimately, on the flow evolution away from the shock.« less

The design of the optical Thomson scattering diagnostic for the National Ignition Facility [The preliminary design of the optical Thomson scattering diagnostic for the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Datte, P. S.; Ross, J. S.; Froula, D. H.

Here, the National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community’s understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot. A deep-UV probe beam (λ 0-210 nm) will be used to optimize the scatteredmore » signal for plasma densities of 5 × 10 20 electrons/cm 3 while a 3ω probe will be used for experiments investigating lower density plasmas of 1 × 10 19 electrons/cm 3. We report the phase I design of a two phase design strategy. Phase I includes the OTS telescope, spectrometer, and streak camera; these will be used to assess the background levels at NIF. Phase II will include the design and installation of a probe laser.« less

Mitigation of hot electrons from laser-plasma instabilities in high-Z, highly ionized plasmas

DOE PAGES

Fein, J. R.; Holloway, J. P.; Trantham, M. R.; ...

2017-03-20

Intense lasers interacting with under-dense plasma can drive laser-plasma instabilities (LPIs) that generate largeamplitude electron plasma waves (EPWs). Suprathermal or “hot” electrons produced in the EPWs are detrimental to inertial confinement fusion (ICF), by reducing capsule implosion efficiency through preheat, and also present an unwanted source of background on x-ray diagnostics. Mitigation of hot electrons was demonstrated in the past by altering plasma conditions near the quarter-critical density, n c/4, with the interpretation of reduced growth of the twoplasmon decay (TPD) instability. Here, we present measurements of hot electrons generated in laser-irradiated planar foils of material ranging from low- tomore » high-Z, where the fraction of laser energy converted to hot electrons, fhot was reduced by a factor of 10 3 going from CH to Au. This correlates with steepening density gradient length-scales that were also measured. Radiation hydrodynamic simulations produced electron density profiles in reasonable agreement with our measurements. According to the simulations, both multi-beam TPD and stimulated Raman scattering were predicted to be above threshold with linear threshold parameters that decreased with increasing Z due to steepening length-scales, as well as enhanced laser absorption and increased EPW collisional and Landau damping.« less

Mitigation of hot electrons from laser-plasma instabilities in high-Z, highly ionized plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fein, J. R.; Holloway, J. P.; Trantham, M. R.

Intense lasers interacting with under-dense plasma can drive laser-plasma instabilities (LPIs) that generate largeamplitude electron plasma waves (EPWs). Suprathermal or “hot” electrons produced in the EPWs are detrimental to inertial confinement fusion (ICF), by reducing capsule implosion efficiency through preheat, and also present an unwanted source of background on x-ray diagnostics. Mitigation of hot electrons was demonstrated in the past by altering plasma conditions near the quarter-critical density, n c/4, with the interpretation of reduced growth of the twoplasmon decay (TPD) instability. Here, we present measurements of hot electrons generated in laser-irradiated planar foils of material ranging from low- tomore » high-Z, where the fraction of laser energy converted to hot electrons, fhot was reduced by a factor of 10 3 going from CH to Au. This correlates with steepening density gradient length-scales that were also measured. Radiation hydrodynamic simulations produced electron density profiles in reasonable agreement with our measurements. According to the simulations, both multi-beam TPD and stimulated Raman scattering were predicted to be above threshold with linear threshold parameters that decreased with increasing Z due to steepening length-scales, as well as enhanced laser absorption and increased EPW collisional and Landau damping.« less

Simulation of Ge Dopant Emission in Indirect-Drive ICF Implosion Experiments

NASA Astrophysics Data System (ADS)

Macfarlane, J. J.; Golovkin, I.; Kulkarni, S.; Regan, S.; Epstein, R.; Mancini, R.; Peterson, K.; Suter, L. J.

2013-10-01

We present results from simulations performed to study the radiative properties of dopants used in inertial confinement fusion indirect-drive capsule implosion experiments on NIF. In Rev5 NIF ignition capsules, a Ge dopant is added to an inner region of the CH ablator to absorb hohlraum x-ray preheat. Spectrally resolved emission from ablator dopants can be used to study the degree of mixing of ablator material into the ignition hot spot. Here, we study the atomic processes that affect the radiative characteristics of these elements using a set of simulation tools to first estimate the evolution of plasma conditions in the compressed target, and then to compute the atomic kinetics of the dopant and the resultant radiative emission. Using estimates of temperature and density profiles predicted by radiation-hydrodynamics simulations, we set up simple 2-D plasma grids where we allow dopant material to be embedded in the fuel, and perform multi-dimensional collisional-radiative simulations using SPECT3D to compute non-LTE atomic level populations and spectral signatures from the dopant. Recently improved Stark-broadened line shape modeling for Ge K-shell lines has been included. The goal is to study the radiative and atomic processes that affect the emergent spectra, including the effects of inner-shell photoabsorption and K α reemission from the dopant.

Fusion Applications and Market Evaluation (FAME) Study

DTIC Science & Technology

1988-02-01

fuel from the breeder. Pyrochemical reprocessing is identified as having the potential for low cost, but needs development . The fast-fission designs... Development Administration, "Alternatives for Man- aging Wastes from Reactors and Post-Fission Operations in the LWR Fuel Cycle," ERDA-76-43 (1976). 5...of the ICF program to produce pulsed radiation for military development applications. X-rays can be converted into UV at about 50% energy efficiency

Effects of large-angle Coulomb collisions on inertial confinement fusion plasmas.

PubMed

Turrell, A E; Sherlock, M; Rose, S J

2014-06-20

Large-angle Coulomb collisions affect the rates of energy and momentum exchange in a plasma, and it is expected that their effects will be important in many plasmas of current research interest, including in inertial confinement fusion. Their inclusion is a long-standing problem, and the first fully self-consistent method for calculating their effects is presented. This method is applied to "burn" in the hot fuel in inertial confinement fusion capsules and finds that the yield increases due to an increase in the rate of temperature equilibration between electrons and ions which is not predicted by small-angle collision theories. The equilibration rate increases are 50%-100% for number densities of 10(30)  m(-3) and temperatures around 1 keV.

Nuclear diagnostic for fast alpha particles

DOEpatents

Grisham, L.R.; Post, D.E. Jr.; Dawson, J.M.

1983-11-23

This invention relates generally to high energy confined plasmas and more particularly is directed to measuring the velocity distribution of confined energetic alpha particles resulting from deuterium-tritium fusion reactions in a confined energetic plasma.

Fluid mechanics of fusion lasers. Final report, September 11, 1978-June 5, 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shwartz, J; Kulkarny, V A; Ausherman, D A

1980-01-01

Flow loop components required to operate continuous-flow, repetitively-pulsed CO/sub 2/ and KrF laser drivers for ICF were identified and their performance requirements were specified. It was found that the laser flow loops can have a major effect on the laser beam quality and overall efficiency. The pressure wave suppressor was identified as the most critical flow loop component. The performance of vented side-wall suppressors was evaluated both analytically and experimentally and found capable of meeting the performance requirements of the CO/sub 2/ and KrF fusion lasers. All other laser flow loop components are essentially similar to those used in conventional,more » low speed wind tunnels and are therefore well characterized and can be readily incorporated into fusion laser flow systems designs.« less

Diagnosing magnetized liner inertial fusion experiments on Z

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hansen, S. B., E-mail: sbhanse@sandia.gov; Gomez, M. R.; Sefkow, A. B.

Magnetized Liner Inertial Fusion experiments performed at Sandia's Z facility have demonstrated significant thermonuclear fusion neutron yields (∼10{sup 12} DD neutrons) from multi-keV deuterium plasmas inertially confined by slow (∼10 cm/μs), stable, cylindrical implosions. Effective magnetic confinement of charged fusion reactants and products is signaled by high secondary DT neutron yields above 10{sup 10}. Analysis of extensive power, imaging, and spectroscopic x-ray measurements provides a detailed picture of ∼3 keV temperatures, 0.3 g/cm{sup 3} densities, gradients, and mix in the fuel and liner over the 1–2 ns stagnation duration.

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

NASA Astrophysics Data System (ADS)

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yongsheng; Graduate School, China Academy of Engineering Physics, Beijing 100088; Gu, Jianfa

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 themore » 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.« less

A Close-Coupled, Heavy Ion ICF Target

NASA Astrophysics Data System (ADS)

Callahan-Miller, Debra A.; Tabak, Max

1998-11-01

A ``close-coupled'' version of the distributed radiator, heavy ion ICF target has produced gain > 130 from 3.1 MJ of ion beam energy. To achieve these results, we reduced the hohlraum dimensions by 27% from our previous designs(M. Tabak, D. Callahan-Miller, D. D.-M. Ho, G. B. Zimmerman, Nuc. Fusion, 38, 509 (1998)) (M. Tabak, D. A. Callahan-Miller, Phys. Plasmas, 5, 1895 (1998).) while driving the same capsule. This reduced the beam energy required from 5.9-6.5 MJ to 3.1 MJ. The smaller hohlraum resulted in a smaller beam spot; elliptically shaped beams with effective radius 1.7 mm were used in this design. In addition to describing this target, we will discuss the effect of the close-coupled hohlraum on the Rayleigh-Taylor instability and scaling this design down to 1.5-2 MJ for an ETF (Engineering Test Facility).

Fusion Propulson System Requirements for an Interstellar Probe

NASA Technical Reports Server (NTRS)

Spencer, D. F.

1963-01-01

An examination of the engine constraints for a fusion-propelled vehicle indicates that minimum flight times for a probe to a 5 light-year star will be approximately 50 years. The principal restraint on the vehicle is the radiator weight and size necessary to dissipate the heat which enters the chamber walls from the fusion plasma. However, it is interesting, at least theoretically, that the confining magnetic field strength is of reasonable magnitude, 2 to 3 x 10(exp5) gauss, and the confinement time is approximately 0.1 sec.

Self-organizing plasma behavior in multiple grid IEC fusion devices for propulsion

NASA Astrophysics Data System (ADS)

McGuire, Thomas; Dietrich, Carl; Sedwick, Raymond

2004-11-01

Inertial Electrostatic Confinement, IEC, of charged particles for the purpose of producing fusion energy is a low mass alternative to more traditional magnetic and inertial confinement fusion schemes. Experimental fusion production and energy efficiency in IEC devices to date has been hindered by confinement limitations. Analysis of the major loss mechanisms suggests that the low pressure beam-beam interaction regime holds the most promise for improved efficiency operation. Numerical simulation of multiple grid schemes shows greatly increased confinement times over contemporary single grid designs by electrostatic focusing of the ion beams. An analytical model of this focusing is presented. With the increased confinement, beams self-organize from a uniform condition into bunches that oscillate at the bounce frequency. The bunches from neighboring beams are then observed to synchronize with each other. Analysis of the anisotropic collisional dynamics responsible for the synchronization is presented. The importance of focusing and density on the beam dynamics are examined. Further, this synchronization appears to modify the particle distribution so as to maintain the non-maxwellian, beam-like energy profile within a bunch. The ability of synchronization to modify and counter-act the thermalization process is examined analytically at the 2-body interaction level and as a conglomeration of particles via numerical simulation. Detailed description of the experiment under development at MIT to investigate the synchronization phenomenon is presented.

Hotspot ignition using a Z-pinch precursor plasma in a magneto-inertial ICF scheme

NASA Astrophysics Data System (ADS)

Chittenden, J. P.; Vincent, P.; Jennings, C. A.; Ciardi, A.

2006-01-01

Precursor plasma flow is a common feature of wire array Z-pinches. The precursor flow represents a fraction of the mass of the array which arrives on the axis early in time and remains confined at high density by the inertia of further material bombarding the axis. Later on, the main implosion of the Z-pinch then compresses this precursor to substantially higher density. We show that if the same system can be generated with a Deuterium-Tritium plasma then the precursor provides an ideal target for a cylindrical magneto-inertial ICF scheme. The implosion of the DT Z-pinch produces a dense, low temperature shell which compressively heats the precursor target to high temperatures and tamps its expansion. The azimuthal magnetic field in the hotspot is sufficient to reduce the Larmor radius for the alpha particles to much less than the hotspot size, which dramatically reduces the pR required for ignition. A computational analysis of this approach is presented, including a study of the thermonuclear burn wave propagation. The robustness of the scheme with respect to instabilities, confinement time and drive parameters is examined. The results indicate that a high energy gain can be achieved using Z-pinches with 50-100 MA currents and a few hundred nanosecond rise-times. This work was partially supported by the U.S. Department of Energy through cooperative agreement DE-FC03-02NA00057.

Theory of plasma confinement in non-axisymmetric magnetic fields.

PubMed

Helander, Per

2014-08-01

The theory of plasma confinement by non-axisymmetric magnetic fields is reviewed. Such fields are used to confine fusion plasmas in stellarators, where in contrast to tokamaks and reversed-field pinches the magnetic field generally does not possess any continuous symmetry. The discussion is focussed on magnetohydrodynamic equilibrium conditions, collisionless particle orbits, and the kinetic theory of equilbrium and transport. Each of these topics is fundamentally affected by the absence of symmetry in the magnetic field: the field lines need not trace out nested flux surfaces, the particle orbits may not be confined, and the cross-field transport can be very large. Nevertheless, by tailoring the magnetic field appropriately, well-behaved equilibria with good confinement can be constructed, potentially offering an attractive route to magnetic fusion. In this article, the mathematical apparatus to describe stellarator plasmas is developed from first principles and basic elements underlying confinement optimization are introduced.

Gasdynamic Mirror (GDM) Fusion Propulsion Engine Experiment

NASA Technical Reports Server (NTRS)

1999-01-01

The Gasdynamic Mirror, or GDM, is an example of a magnetic mirror-based fusion propulsion system. Its design is primarily consisting of a long slender solenoid surrounding a vacuum chamber that contains plasma. The bulk of the fusion plasma is confined by magnetic field generated by a series of toroidal-shaped magnets in the center section of the device. the purpose of the GDM Fusion Propulsion Experiment is to confirm the feasibility of the concept and to demonstrate many of the operational characteristics of a full-size plasma can be confined within the desired physical configuration and still reman stable. This image shows an engineer from Propulsion Research Technologies Division at Marshall Space Flight Center inspecting solenoid magnets-A, an integrate part of the Gasdynamic Mirror Fusion Propulsion Engine Experiment.

Shock ignition: a new approach to high gain inertial confinement fusion on the national ignition facility.

PubMed

Perkins, L J; Betti, R; LaFortune, K N; Williams, W H

2009-07-24

Shock ignition, an alternative concept for igniting thermonuclear fuel, is explored as a new approach to high gain, inertial confinement fusion targets for the National Ignition Facility (NIF). Results indicate thermonuclear yields of approximately 120-250 MJ may be possible with laser drive energies of 1-1.6 MJ, while gains of approximately 50 may still be achievable at only approximately 0.2 MJ drive energy. The scaling of NIF energy gain with laser energy is found to be G approximately 126E (MJ);{0.510}. This offers the potential for high-gain targets that may lead to smaller, more economic fusion power reactors and a cheaper fusion energy development path.

Negative specific heat of a magnetically self-confined plasma torus

PubMed Central

Kiessling, Michael K.-H.; Neukirch, Thomas

2003-01-01

It is shown that the thermodynamic maximum-entropy principle predicts negative specific heat for a stationary, magnetically self-confined current-carrying plasma torus. Implications for the magnetic self-confinement of fusion plasma are considered. PMID:12576553

Computation of Hemagglutinin Free Energy Difference by the Confinement Method

PubMed Central

2017-01-01

Hemagglutinin (HA) mediates membrane fusion, a crucial step during influenza virus cell entry. How many HAs are needed for this process is still subject to debate. To aid in this discussion, the confinement free energy method was used to calculate the conformational free energy difference between the extended intermediate and postfusion state of HA. Special care was taken to comply with the general guidelines for free energy calculations, thereby obtaining convergence and demonstrating reliability of the results. The energy that one HA trimer contributes to fusion was found to be 34.2 ± 3.4kBT, similar to the known contributions from other fusion proteins. Although computationally expensive, the technique used is a promising tool for the further energetic characterization of fusion protein mechanisms. Knowledge of the energetic contributions per protein, and of conserved residues that are crucial for fusion, aids in the development of fusion inhibitors for antiviral drugs. PMID:29151344

Lithium-based surfaces controlling fusion plasma behavior at the plasma-material interfacea)

NASA Astrophysics Data System (ADS)

Allain, Jean Paul; Taylor, Chase N.

2012-05-01

The plasma-material interface and its impact on the performance of magnetically confined thermonuclear fusion plasmas are considered to be one of the key scientific gaps in the realization of nuclear fusion power. At this interface, high particle and heat flux from the fusion plasma can limit the material's lifetime and reliability and therefore hinder operation of the fusion device. Lithium-based surfaces are now being used in major magnetic confinement fusion devices and have observed profound effects on plasma performance including enhanced confinement, suppression and control of edge localized modes (ELM), lower hydrogen recycling and impurity suppression. The critical spatial scale length of deuterium and helium particle interactions in lithium ranges between 5-100 nm depending on the incident particle energies at the edge and magnetic configuration. Lithium-based surfaces also range from liquid state to solid lithium coatings on a variety of substrates (e.g., graphite, stainless steel, refractory metal W/Mo/etc., or porous metal structures). Temperature-dependent effects from lithium-based surfaces as plasma facing components (PFC) include magnetohydrodynamic (MHD) instability issues related to liquid lithium, surface impurity, and deuterium retention issues, and anomalous physical sputtering increase at temperatures above lithium's melting point. The paper discusses the viability of lithium-based surfaces in future burning-plasma environments such as those found in ITER and DEMO-like fusion reactor devices.

Simulation of High-Beta Plasma Confinement

NASA Astrophysics Data System (ADS)

Font, Gabriel; Welch, Dale; Mitchell, Robert; McGuire, Thomas

2017-10-01

The Lockheed Martin Compact Fusion Reactor concept utilizes magnetic cusps to confine the plasma. In order to minimize losses through the axial and ring cusps, the plasma is pushed to a high-beta state. Simulations were made of the plasma and magnetic field system in an effort to quantify particle confinement times and plasma behavior characteristics. Computations are carried out with LSP using implicit PIC methods. Simulations of different sub-scale geometries at high-Beta fusion conditions are used to determine particle loss scaling with reactor size, plasma conditions, and gyro radii. ©2017 Lockheed Martin Corporation. All Rights Reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baylor, Larry R.; Meitner, Steven J.

Magnetically confined fusion plasmas generate energy from deuterium-tritium (DT) fusion reactions that produce energetic 3.5 MeV alpha particles and 14 MeV neutrons. Since the DT fusion reaction rate is a strong function of plasma density, an efficient fueling source is needed to maintain high plasma density in such systems. Energetic ions in fusion plasmas are able to escape the confining magnetic fields at a much higher rate than the fusion reactions occur, thus dictating the fueling rate needed. These lost ions become neutralized and need to be pumped away as exhaust gas to be reinjected into the plasma as fuelmore » atoms.The technology to fuel and pump fusion plasmas has to be inherently compatible with the tritium fuel. An ideal holistic solution would couple the pumping and fueling such that the pump exhaust is directly fed back into pellet formation without including impurity gases. This would greatly reduce the processing needs for the exhaust. Concepts to accomplish this are discussed along with the fueling and pumping needs for a DT fusion reactor.« less

Fuel gain exceeding unity in an inertially confined fusion implosion.

PubMed

Hurricane, O A; Callahan, D A; Casey, D T; Celliers, P M; Cerjan, C; Dewald, E L; Dittrich, T R; Döppner, T; Hinkel, D E; Berzak Hopkins, L F; Kline, J L; Le Pape, S; Ma, T; MacPhee, A G; Milovich, J L; Pak, A; Park, H-S; Patel, P K; Remington, B A; Salmonson, J D; Springer, P T; Tommasini, R

2014-02-20

Ignition is needed to make fusion energy a viable alternative energy source, but has yet to be achieved. A key step on the way to ignition is to have the energy generated through fusion reactions in an inertially confined fusion plasma exceed the amount of energy deposited into the deuterium-tritium fusion fuel and hotspot during the implosion process, resulting in a fuel gain greater than unity. Here we report the achievement of fusion fuel gains exceeding unity on the US National Ignition Facility using a 'high-foot' implosion method, which is a manipulation of the laser pulse shape in a way that reduces instability in the implosion. These experiments show an order-of-magnitude improvement in yield performance over past deuterium-tritium implosion experiments. We also see a significant contribution to the yield from α-particle self-heating and evidence for the 'bootstrapping' required to accelerate the deuterium-tritium fusion burn to eventually 'run away' and ignite.

Effects of fuel-capsule shimming and drive asymmetry on inertial-confinement-fusion symmetry and yield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Séguin, F. H.; Li, C. K.; DeCiantis, J. L.

Three orthogonal proton emission imaging cameras were used to study the 3D effects of low-mode drive asymmetries and target asymmetries on nuclear burn symmetry and yield in direct-drive, inertial-confinement-fusion experiments. The fusion yield decreased quickly as the burn region became asymmetric due to either drive or capsule asymmetry. Measurements and analytic scaling are used to predict how intentionally asymmetric capsule shells could improve performance by compensating for drive asymmetry when it cannot be avoided (such as with indirect drive or with polar direct drive).

Effects of fuel-capsule shimming and drive asymmetry on inertial-confinement-fusion symmetry and yield

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seguin, F. H.; Li, C. K.; DeCiantis, J. L.

Three orthogonal proton emission imaging cameras were used to study the 3D effects of low-mode drive asymmetries and target asymmetries on nuclear burn symmetry and yield in direct-drive, inertial-confinement-fusion experiments. The fusion yield decreased quickly as the burn region became asymmetric due to either drive or capsule asymmetry. Furthermore, measurements and analytic scaling are used to predict how intentionally asymmetric capsule shells could improve performance by compensating for drive asymmetry when it cannot be avoided (such as with indirect drive or with polar direct drive).

Aperture tolerances for neutron-imaging systems in inertial confinement fusion.

PubMed

Ghilea, M C; Sangster, T C; Meyerhofer, D D; Lerche, R A; Disdier, L

2008-02-01

Neutron-imaging systems are being considered as an ignition diagnostic for the National Ignition Facility (NIF) [Hogan et al., Nucl. Fusion 41, 567 (2001)]. Given the importance of these systems, a neutron-imaging design tool is being used to quantify the effects of aperture fabrication and alignment tolerances on reconstructed neutron images for inertial confinement fusion. The simulations indicate that alignment tolerances of more than 1 mrad would introduce measurable features in a reconstructed image for both pinholes and penumbral aperture systems. These simulations further show that penumbral apertures are several times less sensitive to fabrication errors than pinhole apertures.

Effects of fuel-capsule shimming and drive asymmetry on inertial-confinement-fusion symmetry and yield

DOE PAGES

Seguin, F. H.; Li, C. K.; DeCiantis, J. L.; ...

2016-03-22

Three orthogonal proton emission imaging cameras were used to study the 3D effects of low-mode drive asymmetries and target asymmetries on nuclear burn symmetry and yield in direct-drive, inertial-confinement-fusion experiments. The fusion yield decreased quickly as the burn region became asymmetric due to either drive or capsule asymmetry. Furthermore, measurements and analytic scaling are used to predict how intentionally asymmetric capsule shells could improve performance by compensating for drive asymmetry when it cannot be avoided (such as with indirect drive or with polar direct drive).

Use of /sup 3/He/sup + +/ ICRF minority heating to simulate alpha particle heating

DOEpatents

Post, D.E. Jr.; Hwang, D.Q.; Hovey, J.

1983-11-16

It is an object of the present invention to provide a better understanding of alpha particle behavior in a magnetically confined, energetic plasma. Another object of the present invention is to provide an improved means and method for studying and measuring the energy distribution of heated alpha particles in a confined plasma. Yet another object of the present invention is to permit detailed analysis of energetic alpha particle behavior in a magnetically confined plasma for use in near term fusion reactor experiments. A still further object of the present invention is to simulate energetic alpha particle behavior in a deuterium-tritium plasma confined in a fusion reactor without producing the neutron activation associated with the thus produced alpha particles.

Understanding fuel magnetization and mix using secondary nuclear reactions in magneto-inertial fusion.

PubMed

Schmit, P F; Knapp, P F; Hansen, S B; Gomez, M R; Hahn, K D; Sinars, D B; Peterson, K J; Slutz, S A; Sefkow, A B; Awe, T J; Harding, E; Jennings, C A; Chandler, G A; Cooper, G W; Cuneo, M E; Geissel, M; Harvey-Thompson, A J; Herrmann, M C; Hess, M H; Johns, O; Lamppa, D C; Martin, M R; McBride, R D; Porter, J L; Robertson, G K; Rochau, G A; Rovang, D C; Ruiz, C L; Savage, M E; Smith, I C; Stygar, W A; Vesey, R A

2014-10-10

Magnetizing the fuel in inertial confinement fusion relaxes ignition requirements by reducing thermal conductivity and changing the physics of burn product confinement. Diagnosing the level of fuel magnetization during burn is critical to understanding target performance in magneto-inertial fusion (MIF) implosions. In pure deuterium fusion plasma, 1.01 MeV tritons are emitted during deuterium-deuterium fusion and can undergo secondary deuterium-tritium reactions before exiting the fuel. Increasing the fuel magnetization elongates the path lengths through the fuel of some of the tritons, enhancing their probability of reaction. Based on this feature, a method to diagnose fuel magnetization using the ratio of overall deuterium-tritium to deuterium-deuterium neutron yields is developed. Analysis of anisotropies in the secondary neutron energy spectra further constrain the measurement. Secondary reactions also are shown to provide an upper bound for the volumetric fuel-pusher mix in MIF. The analysis is applied to recent MIF experiments [M. R. Gomez et al., Phys. Rev. Lett. 113, 155003 (2014)] on the Z Pulsed Power Facility, indicating that significant magnetic confinement of charged burn products was achieved and suggesting a relatively low-mix environment. Both of these are essential features of future ignition-scale MIF designs.

Using gamma-ray emission to measure areal density of inertial confinement fusion capsulesa)

NASA Astrophysics Data System (ADS)

Hoffman, N. M.; Wilson, D. C.; Herrmann, H. W.; Young, C. S.

2010-10-01

Fusion neutrons streaming from a burning inertial confinement fusion capsule generate gamma rays via inelastic nuclear scattering in the ablator of the capsule. The intensity of gamma-ray emission is proportional to the product of the ablator areal density (ρR) and the yield of fusion neutrons, so by detecting the gamma rays we can infer the ablator areal density, provided we also have a measurement of the capsule's total neutron yield. In plastic-shell capsules, for example, C12 nuclei emit gamma rays at 4.44 MeV after excitation by 14.1 MeV neutrons from D+T fusion. These gamma rays can be measured by a new gamma-ray detector under development. Analysis of predicted signals is in progress, with results to date indicating that the method promises to be useful for diagnosing imploded capsules.

Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse.

PubMed

Bang, W

2015-07-01

Energetic deuterium ions from large deuterium clusters (>10nm diameter) irradiated by an intense laser pulse (>10(16)W/cm(2)) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We present an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the available experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10-keV deuterium fusion plasma for 10ns.

A comprehensive alpha-heating model for inertial confinement fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christopherson, A. R.; Betti, R.; Bose, A.

In this paper, a comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot confined by a compressible shell, heated by fusion alphas, and cooled by radiation and thermal losses. The model includes the deceleration, stagnation, and burn phases of inertial confinement fusion implosions, and is valid for sub-ignited targets with ≤10× amplification of the fusion yield from alpha-heating. The results of radiation-hydrodynamic simulations are used to derive realistic initial conditions and dimensionless parameters for the model. It is found that most of the alpha energy (~90%) producedmore » before bang time is deposited within the hot spot mass, while a small fraction (~10%) drives mass ablation off the inner shell surface and its energy is recycled back into the hot spot. Of the bremsstrahlung radiation emission, ~40% is deposited in the hot spot, ~40% is recycled back in the hot spot by ablation off the shell, and ~20% leaves the hot spot. We show here that the hot spot, shocked shell, and outer shell trajectories from this analytical model are in good agreement with simulations. Finally, a detailed discussion of the effect of alpha-heating on the hydrodynamics is also presented.« less

A comprehensive alpha-heating model for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Christopherson, A. R.; Betti, R.; Bose, A.; Howard, J.; Woo, K. M.; Campbell, E. M.; Sanz, J.; Spears, B. K.

2018-01-01

A comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot confined by a compressible shell, heated by fusion alphas, and cooled by radiation and thermal losses. The model includes the deceleration, stagnation, and burn phases of inertial confinement fusion implosions, and is valid for sub-ignited targets with ≤10 × amplification of the fusion yield from alpha-heating. The results of radiation-hydrodynamic simulations are used to derive realistic initial conditions and dimensionless parameters for the model. It is found that most of the alpha energy (˜90%) produced before bang time is deposited within the hot spot mass, while a small fraction (˜10%) drives mass ablation off the inner shell surface and its energy is recycled back into the hot spot. Of the bremsstrahlung radiation emission, ˜40% is deposited in the hot spot, ˜40% is recycled back in the hot spot by ablation off the shell, and ˜20% leaves the hot spot. We show here that the hot spot, shocked shell, and outer shell trajectories from this analytical model are in good agreement with simulations. A detailed discussion of the effect of alpha-heating on the hydrodynamics is also presented.

A comprehensive alpha-heating model for inertial confinement fusion

DOE PAGES

Christopherson, A. R.; Betti, R.; Bose, A.; ...

2018-01-08

In this paper, a comprehensive model is developed to study alpha-heating in inertially confined plasmas. It describes the time evolution of a central low-density hot spot confined by a compressible shell, heated by fusion alphas, and cooled by radiation and thermal losses. The model includes the deceleration, stagnation, and burn phases of inertial confinement fusion implosions, and is valid for sub-ignited targets with ≤10× amplification of the fusion yield from alpha-heating. The results of radiation-hydrodynamic simulations are used to derive realistic initial conditions and dimensionless parameters for the model. It is found that most of the alpha energy (~90%) producedmore » before bang time is deposited within the hot spot mass, while a small fraction (~10%) drives mass ablation off the inner shell surface and its energy is recycled back into the hot spot. Of the bremsstrahlung radiation emission, ~40% is deposited in the hot spot, ~40% is recycled back in the hot spot by ablation off the shell, and ~20% leaves the hot spot. We show here that the hot spot, shocked shell, and outer shell trajectories from this analytical model are in good agreement with simulations. Finally, a detailed discussion of the effect of alpha-heating on the hydrodynamics is also presented.« less

Ohmic ignition with high engineering beta based on the RFP

NASA Astrophysics Data System (ADS)

Sarff, J. S.; Anderson, J. K.; Chapman, B. E.; McCollam, K. J.

2017-10-01

The RFP configuration allows the possibility of ohmic ignition for fusion energy, eliminating the need for auxiliary heating by rf or neutral beam injection. Complex plasma-facing antennas and NBI sources are therefore not required, simplifying the difficult fusion materials challenge. While all toroidal configurations require a volume-average 〈 B 〉 >= 5 T, the field strength at the magnet in the RFP is only Bcoil 3T since plasma current generates almost all of the field. Engineering beta is therefore maximized. We summarize access to ohmic ignition by examining a Lawson-like power balance for an RFP fusion plasma comparable to the ARIES-AT advanced tokamak, which generates neutron wall loading Pn / A 5 MW/m2. The required energy confinement for ohmic ignition in an RFP is similar to that for a tokamak. Confinement in MST is comparable to a same-size, same-field tokamak plasma, but 〈 B 〉 in MST is only 1/20th that required for fusion. While transport could ultimately be dominated by micro turbulence, extrapolation of stochastic transport using Lundquist number scaling for MHD tearing indicates standard RFP confinement (not enhanced by current profile control) could be sufficient to access ohmic ignition. This bolsters the possibility for steady-state inductive sustainment using oscillating field current drive. The high beta and classical energetic ion confinement measured in MST also bolster the RFP's fusion potential. Work supported by U.S. DoE.

Research Technology

NASA Image and Video Library

1999-05-12

The Gasdynamic Mirror, or GDM, is an example of a magnetic mirror-based fusion propulsion system. Its design is primarily consisting of a long slender solenoid surrounding a vacuum chamber that contains plasma. The bulk of the fusion plasma is confined by magnetic field generated by a series of toroidal-shaped magnets in the center section of the device. the purpose of the GDM Fusion Propulsion Experiment is to confirm the feasibility of the concept and to demonstrate many of the operational characteristics of a full-size plasma can be confined within the desired physical configuration and still reman stable. This image shows an engineer from Propulsion Research Technologies Division at Marshall Space Flight Center inspecting solenoid magnets-A, an integrate part of the Gasdynamic Mirror Fusion Propulsion Engine Experiment.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruenwald, J., E-mail: johannes.gruenwald@inp-greifswald.de; Fröhlich, M.

A model of the behavior of transit time instabilities in an electrostatic confinement fusion reactor is presented in this letter. It is demonstrated that different modes are excited within the spherical cathode of a Farnsworth fusor. Each of these modes is dependent on the fusion products as well as the acceleration voltage applied between the two electrodes and they couple to a resulting oscillation showing non-linear beat phenomena. This type of instability is similar to the transit time instability of electrons between two resonant surfaces but the presence of ions and the occurring fusion reactions alter the physics of thismore » instability considerably. The physics of this plasma instability is examined in detail for typical physical parameter ranges of electrostatic confinement fusion devices.« less

Introduction to Nuclear Fusion Power and the Design of Fusion Reactors. An Issue-Oriented Module.

ERIC Educational Resources Information Center

Fillo, J. A.

This three-part module focuses on the principles of nuclear fusion and on the likely nature and components of a controlled-fusion power reactor. The physical conditions for a net energy release from fusion and two approaches (magnetic and inertial confinement) which are being developed to achieve this goal are described. Safety issues associated…

Status and problems of fusion reactor development.

PubMed

Schumacher, U

2001-03-01

Thermonuclear fusion of deuterium and tritium constitutes an enormous potential for a safe, environmentally compatible and sustainable energy supply. The fuel source is practically inexhaustible. Further, the safety prospects of a fusion reactor are quite favourable due to the inherently self-limiting fusion process, the limited radiologic toxicity and the passive cooling property. Among a small number of approaches, the concept of toroidal magnetic confinement of fusion plasmas has achieved most impressive scientific and technical progress towards energy release by thermonuclear burn of deuterium-tritium fuels. The status of thermonuclear fusion research activity world-wide is reviewed and present solutions to the complicated physical and technological problems are presented. These problems comprise plasma heating, confinement and exhaust of energy and particles, plasma stability, alpha particle heating, fusion reactor materials, reactor safety and environmental compatibility. The results and the high scientific level of this international research activity provide a sound basis for the realisation of the International Thermonuclear Experimental Reactor (ITER), whose goal is to demonstrate the scientific and technological feasibility of a fusion energy source for peaceful purposes.

X-ray shadow imprint of hydrodynamic instabilities on the surface of inertial confinement fusion capsules by the fuel fill tube

DOE PAGES

MacPhee, A. G.; Casey, D. T.; Clark, D. S.; ...

2017-03-30

Measurements of hydrodynamic instability growth for a high-density carbon ablator for indirectly driven inertial confinement fusion implosions on the National Ignition Facility are reported. We observe significant unexpected features on the capsule surface created by shadows of the capsule fill tube, as illuminated by laser-irradiated x-ray spots on the hohlraum wall. These shadows increase the spatial size and shape of the fill tube perturbation in a way that can significantly degrade performance in layered implosions compared to previous expectations. The measurements were performed at a convergence ratio of ~2 using in-flight x-ray radiography. The initial seed due to shadow imprintmore » is estimated to be equivalent to ~50–100 nm of solid ablator material. As a result, this discovery has prompted the need for a mitigation strategy for future inertial confinement fusion designs as proposed here.« less

X-ray shadow imprint of hydrodynamic instabilities on the surface of inertial confinement fusion capsules by the fuel fill tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacPhee, A. G.; Casey, D. T.; Clark, D. S.

Measurements of hydrodynamic instability growth for a high-density carbon ablator for indirectly driven inertial confinement fusion implosions on the National Ignition Facility are reported. We observe significant unexpected features on the capsule surface created by shadows of the capsule fill tube, as illuminated by laser-irradiated x-ray spots on the hohlraum wall. These shadows increase the spatial size and shape of the fill tube perturbation in a way that can significantly degrade performance in layered implosions compared to previous expectations. The measurements were performed at a convergence ratio of ~2 using in-flight x-ray radiography. The initial seed due to shadow imprintmore » is estimated to be equivalent to ~50–100 nm of solid ablator material. As a result, this discovery has prompted the need for a mitigation strategy for future inertial confinement fusion designs as proposed here.« less

P2 Asymmetry of Au's M-band Flux and its smoothing effect due to high-Z ablator dopants

NASA Astrophysics Data System (ADS)

Li, Yongsheng; Zhai, Chuanlei; Ren, Guoli; Gu, Jianfa; Huo, Wenyi; Meng, Xujun; Ye, Wenhua; Lan, Ke; Zhang, Weiyan

2017-10-01

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. More particularly, the P2 asymmetry of Au's M-band flux can also severely influence the implosion performance. Here we study the smoothing effect of mid- and/or high-Z dopants in ablator on M-band flux asymmetries, by modeling and comparing the implosion processes of a Ge-doped and a Si-doped ignition capsule driven by x-ray sources with asymmetric M-band flux. As the results, (1) mid- or high-Z dopants absorb M-band flux and re-emit isotropically, helping to smooth 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 due to its higher opacity than the latter in Au's M-band; 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.

Heavy ion beams from an Alphatross source for use in calibration and testing of diagnostics

NASA Astrophysics Data System (ADS)

Ward, R. J.; Brown, G. M.; Ho, D.; Stockler, B. F. O. F.; Freeman, C. G.; Padalino, S. J.; Regan, S. P.

2016-10-01

Ion beams from the 1.7 MV Pelletron Accelerator at SUNY Geneseo have been used to test and calibrate many inertial confinement fusion (ICF) diagnostics and high energy density physics (HEDP) diagnostics used at the Laboratory for Laser Energetics (LLE). The ion source on this accelerator, a radio-frequency (RF) alkali-metal charge exchange source called an Alphatross, is designed to produce beams of hydrogen and helium isotopes. There is interest in accelerating beams of carbon, oxygen, argon, and other heavy ions for use in testing several diagnostics, including the Time Resolved Tandem Faraday Cup (TRTF). The feasibility of generating these heavy ion beams using the Alphatross source will be reported. Small amounts of various gases are mixed into the helium plasma in the ion source bottle. A velocity selector is used to allow the desired ions to pass into the accelerator. As the heavy ions pass through the stripper canal of the accelerator, they emerge in a variety of charge states. The energy of the ion beam at the high-energy end of the accelerator will vary as a function of the charge state, however the maximum energy deliverable to target is limited by the maximum achievable magnetic field produced by the accelerator's steering magnet. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

ICF Gamma-Ray measurements on the NIF

NASA Astrophysics Data System (ADS)

Herrmann, Hans; Kim, Y.; Hoffman, N. M.; Batha, S. H.; Stoeffl, W.; Church, J. A.; Sayre, D. B.; Liebman, J. A.; Cerjan, C. J.; Carpenter, A. C.; Grafil, E. M.; Khater, H. Y.; Horsfield, C. J.; Rubery, M.

2013-10-01

The primary objective of the NIF Gamma Reaction History (GRH) diagnostic is to provide bang time and burn width information in order to constrain implosion simulation parameters such as shell velocity and confinement time. This is accomplished by measuring DT fusion gamma-rays with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. Burn-weighted CH ablator areal density is also inferred based on measurement of the 12C(n,n') gammas emitted at 4.44 MeV from DT neutrons inelastically scattering off carbon nuclei as they pass through the plastic ablator. This requires that the four independent GRH gas cells be set to differing Cherenkov thresholds (e.g., 2.9, 4.5, 8 & 10 MeV) in order to be able to unfold the primary spectral components predicted to be in the gamma ray energy spectrum (i.e., DT γ 27Al & 28Si (n,n') γ from the thermo-mechanical package (TMP); and 12C(n,n' γ from the ablator). The GRH response to 12C(n,n') γ is calibrated in-situ by placing a known areal density of carbon in the form of a puck placed ~6 cm from a DT exploding pusher implosion. Comparisons between inferred gamma fluences and simulations based on the nuclear cross sections databases will be presented. Supported by US DOE NNSA.

Simulation of Ge Dopant Emission in Indirect-Drive ICF Implosion Experiments

NASA Astrophysics Data System (ADS)

Macfarlane, Joseph; Golovkin, I.; Regan, S.; Epstein, R.; Mancini, R.; Peterson, K.; Suter, L.

2012-10-01

We present results from simulations performed to study the radiative properties of dopants used in inertial confinement fusion indirect-drive capsule implosion experiments on NIF. In Rev5 NIF ignition capsules, a Ge dopant is added to an inner region of the CH ablator to absorb hohlraum x-ray preheat. Spectrally resolved emission from ablator dopants can be used to study the degree of mixing of ablator material into the ignition hot spot. Here, we study the atomic processes that affect the radiative characteristics of these elements using a set of simulation tools to first estimate the evolution of plasma conditions in the compressed target, and then to compute the atomic kinetics of the dopant and the resultant radiative emission. Using estimates of temperature and density profiles predicted by radiation-hydrodynamics simulations, we set up simple plasma grids where we allow dopant material to be embedded in the fuel, and perform multi-dimensional collisional-radiative simulations using SPECT3D to compute non-LTE atomic level populations and spectral signatures from the dopant. Recently improved Stark-broadened line shape modeling for Ge K-shell lines has been included. The goal is to study the radiative and atomic processes that affect the emergent spectra, including the effects of inner-shell photoabsorption and Kα reemission from the dopant, and to study the sensitivity of the emergent spectra to the dopant and the hot spot and ablator conditions.

Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

DOEpatents

Rostoker, Norman [Irvine, CA; Binderbauer, Michl [Irvine, CA; Qerushi, Artan [Irvine, CA; Tahsiri, Hooshang [Irvine, CA

2008-10-21

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

DOEpatents

Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

2006-10-10

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2013-06-11

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2016-07-05

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2006-10-31

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman; Binderbauer, Michl

2006-04-11

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Apparatus for magnetic and electrostatic confinement of plasma

DOEpatents

Rostoker, Norman [Irvine, CA; Binderbauer, Michl [Irvine, CA

2009-08-04

An apparatus and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions ions are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Magnetic and electrostatic confinement of plasma with tuning of electrostatic field

DOEpatents

Rostoker, Norman; Binderbauer, Michl; Qerushi, Artan; Tahsiri, Hooshang

2006-03-21

A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.

Fusion energy division annual progress report, period ending December 31, 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1981-11-01

The ORNL Program encompasses most aspects of magnetic fusion research including research on two magnetic confinement programs (tokamaks and ELMO bumpy tori); the development of the essential technologies for plasma heating, fueling, superconducting magnets, and materials; the development of diagnostics; the development of atomic physics and radiation effect data bases; the assessment of the environmental impact of magnetic fusion; the physics and engineering of present-generation devices; and the design of future devices. The integration of all of these activities into one program is a major factor in the success of each activity. An excellent example of this integration is themore » extremely successful application of neutral injection heating systems developed at ORNL to tokamaks both in the Fusion Energy Division and at Princeton Plasma Physics Laboratory (PPPL). The goal of the ORNL Fusion Program is to maintain this balance between plasma confinement, technology, and engineering activities.« less

Disassembly time of deuterium-cluster-fusion plasma irradiated by an intense laser pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bang, W.

Energetic deuterium ions from large deuterium clusters (>10 nm diameter) irradiated by an intense laser pulse (>10¹⁶ W/cm²) produce DD fusion neutrons for a time interval determined by the geometry of the resulting fusion plasma. We show an analytical solution of this time interval, the plasma disassembly time, for deuterium plasmas that are cylindrical in shape. Assuming a symmetrically expanding deuterium plasma, we calculate the expected fusion neutron yield and compare with an independent calculation of the yield using the concept of a finite confinement time at a fixed plasma density. The calculated neutron yields agree quantitatively with the availablemore » experimental data. Our one-dimensional simulations indicate that one could expect a tenfold increase in total neutron yield by magnetically confining a 10 - keV deuterium fusion plasma for 10 ns.« less