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The National Ignition Campaign (NIC) will use non-igniting THD capsules with cryogenic ice layers to study and optimize the hydrodynamic assembly of the fuel without burn. These capsules are characterized by the ratios of T:H:D. The species ratios are set with two goals in mind: (1) control T:D in order to adjust the nuclear energy production and (2) preserve the average atomic number of the fuel at 2.5 to maintain hydrodynamic similarity with the DT ignition capsule. We have developed an experimentally observable ignition threshold factor (ITFX) that uses measurements from THD experiments to predict the performance of DT ignition implosions. It was developed and tested on multiple large databases of 2D radhydro simulations. Each of the thousands of simulations includes twin DT and THD simulations with a variety of physical failure mechanisms – drive asymmetry, capsule roughness, continuum mixing, fabrication errors, among others. The results of our numerical database and the ITFX metric have allowed us to develop an experimental estimate of the probability of DT ignition based on THD experiments. The analysis accounts for both diagnostic precision and the effects of a finite number of shots. The NIC expects to field a combination of diagnostics and experimental attempts that result in a 15 to 20 percent uncertainty in the experimentally inferred probability of ignition. This work was completed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52–07NA27344.

For the first time high areal-density (ρR) cryogenic deuterium-tritium (DT) implosions have been probed using downscattered neutron spectra measured with the magnetic recoil spectrometer (MRS) [J. A. Frenje et al., Rev. Sci. Instrum. 79, 10E502 (2008)], recently installed and commissioned on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The ρR data obtained with the MRS have been essential for understanding how the fuel is assembled and for guiding the cryogenic program at the Laboratory for Laser Energetics (LLE) to ρR values up to ∼300 mg/cm2. The ρR data obtained from well-established charged particle spectrometry techniques [C. K. Li et al., Phys. Plasmas 8, 4902 (2001)] were used to authenticate the MRS data for low-ρR plastic capsule implosions, and the ρR values inferred from these techniques are in excellent agreement, indicating that the MRS technique provides high-fidelity data. Recent OMEGA-MRS data and Monte Carlo simulations have shown that the MRS on the NIF [G. H. Miller et al....

Experimental results showing hot electron penetration into Cu wires using Kα fluorescence imaging are presented. A 500 J, 1 ps laser was focused at f/3 into hollow aluminum cones joined at their tip to Cu wires of diameters from 10 to 40 μm. Comparison of the axially diminishing absolute intensity of Cu Kα with modeling shows that the penetration of the electrons is consistent with one dimensional Ohmic potential limited transport. The laser coupling efficiency to electron energy within the wire is shown to be proportional to the cross sectional area of the wire, reaching 15% for 40 μm wires. Further, we find the hot electron temperature within the wire to be about 750 keV. The relevance of these data to cone coupled fast ignition is discussed. © 2009 American Institute of Physics.

By fielding several compact proton spectrometers at various locations around an ignition-capsule implosion at the National Ignition Facility [G. H. Miller, E. I. Moses, and C. R. Wuest, Nucl. Fusion 44, S228 (2004)], ρR and ρR asymmetries of the ablator for a failed implosion can be obtained through absolute measurements of knock-on proton (KO-P) spectra. For ignition capsules with a Cu-doped beryllium (Be) ablator, 50:50 mixture of deuterium-tritium (DT) fuel and ∼1% residual hydrogen (H) by atom, failed implosions can be diagnosed for neutron yields ranging from ∼1011 to ∼6×1015 and local ρRs up to ∼240mg∕cm2. For capsules with an ablator of Ge-doped CH, which contains a large amounts of H, failed implosions can be diagnosed for neutron yields ranging from ∼1010 to ∼6×1015 and local ρRs up to ∼200mg∕cm2. Prior to the first ignition experiments, capsules with a Cu-doped Be ablator (or Ge-doped CH ablator), more deuterium-lean fuel mixture and H-dopant levels up to 25% in the fuel will be imploded to prim...

We have developed 17 keV to 75 keV 1-dimensional and 2-dimensional high-resolution ( 10{sup 17} W/cm{sup 2}. We have achieved high resolution point projection 1-dimensional and 2-dimensional radiography using micro-foil and micro-wire targets attached to low-Z substrate materials. The micro-wire size was 10 {micro}m x 10 {micro}m x 300 {micro}m on a 300 {micro}m x 300 {micro}m x 5 {micro}m CH substrate. The radiography performance was demonstrated using the Titan laser at LLNL. We observed that the resolution is dominated by the micro-wire target size and there is very little degradation from the plasma plume, implying that the high energy x-ray photons are generated mostly within the micro-wire volume. We also observe that there are enough K{alpha} photons created with a 300 J, 1-{omega}, 40 ps pulse laser from these small volume targets, and that the signal-to-noise ratio is sufficiently high, for single shot radiography experiments. This unique technique will be used on future high energy density (HED) experiments at the new Omega-EP, ZR and NIF facilities.

Fast ignition research has reached the stage where point designs are becoming crucial to the identification of key issues and the development of projects to demonstrate high gain fast ignition. The status of point designs for cone coupled electron fast ignition and some of the issues they highlight are discussed.

Measurements of plasma temperature at the rear surface of foil targets due to heating by hot electrons, which were produced in short pulse high intensity laser matter interactions using the 150 J, 0.5 ps Titan laser, are reported. Extreme ultraviolet (XUV) imaging at 256 and 68 eV energies is used to determine spatially resolved target rear surface temperature patterns by comparing absolute intensities to radiation hydrodynamic modeling. XUV mirrors at these two energies were absolutely calibrated at the Advanced Light Source at the Lawrence Berkeley Laboratory. Temperatures deduced from both imagers are validated against each other within the range of 75-225 eV.

Experiments have been performed on the OMEGA Laser Facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] to study the hydrodynamics of directly driven cone-in-shell, fast-ignitor targets. A 35° or 70° opening-angle gold cone was inserted into spherical plastic shells of ∼24-μm thickness and ∼870-μm diameter, which were imploded with up to 21kJ of 351-nm laser light. A backlighter was used on some experiments to compare the fuel assembly of targets with or without a high-pressure fill gas. The shock breakthrough to the inside of the cone, where the ultrafast laser propagates in integrated fast-ignitor experiments, was studied using a streaked optical pyrometer. No plasma was seen inside the cone before the assembled core reached peak compression.

The results of laser-driven proton beam focusing and heating with a high energy (170J) short pulse are reported. Thin hemispherical aluminum shells are illuminated with the Gekko petawatt laser using 1μm light at intensities of ∼3×1018W∕cm2 and measured heating of thin Al slabs. The heating pattern is inferred by imaging visible and extreme-ultraviolet light Planckian emission from the rear surface. When Al slabs 100μm thick were placed at distances spanning the proton focus beam waist, the highest temperatures were produced at 0.94× the hemisphere radius beyond the equatorial plane. Isochoric heating temperatures reached 81eV in 15μm thick foils. The heating with a three-dimensional Monte Carlo model of proton transport with self-consistent heating and proton stopping in hot plasma was modeled.

The interaction of a 75 J 10 ps, high intensity laser beam with low-mass, solid Cu targets is investigated. Two instruments were fielded as diagnostics of Cu K -shell emission from the targets: a single photon counting spectrometer provided the absolute Kα yield [C. Stoeckl, Rev. Sci. Instrum. 75, 3705 (2004)] and a spherically bent Bragg crystal recorded 2D monochromatic images with a spatial resolution of 10 μm [J. A. Koch, Rev. Sci. Instrum. 74, 2130 (2003)]. Due to the shifting and broadening of the Kα spectral lines with increasing temperature, there is a temperature dependence of the crystal collection efficiency. This affects measurements of the spatial pattern of electron transport, and it provides a temperature diagnostic when cross calibrated against the single photon counting spectrometer. The experimental data showing changing collection efficiency are presented. The results are discussed in light of modeling of the temperature-dependent spectrum of Cu K -shell emission. © 2007 American Institute of Physics.

A 68 eV extreme-ultraviolet light imaging diagnostic measures short pulse isochoric heating by electrons and protons in petawatt laser experiments. Temperatures are deduced from the absolute intensities and comparison with modeling using a radiation hydrodynamics code.

The National Ignition Facility (NIF) will provide up to 1.8MJ of laser energy for imploding inertial confinement fusion (ICF) targets. Ignited NIF targets are expected to produce up to 1019 DT neutrons. This will provide unprecedented opportunities and challenges for the use of nuclear diagnostics in ICF experiments. In 2005, the suite of nuclear-ignition diagnostics for the NIF was defined and they are under development through collaborative efforts at several institutions. This suite includes PROTEX and copper activation for primary yield measurements, a magnetic recoil spectrometer and carbon activation for fuel areal density, neutron time-of-flight detectors for yield and ion temperature, a gamma bang time detector, and neutron imaging systems for primary and downscattered neutrons. An overview of the conceptual design, the developmental status, and recent results of prototype tests on the OMEGA laser will be presented.

A novel monoenergetic proton backlighter source and matched imaging detector have been utilized on the OMEGA laser system to study electric (E) and magnetic (B) fields generated by laser-plasma interactions and will be utilized in the future to radiograph implosions and high-energy density (HED) plasmas. The backlighter consists of an imploding glass microballoon with DHe3 fuel, producing 14.7MeV DHe3 protons and 3MeV DD protons that are then passed through a mesh that divides the protons into beamlets. For quantitative study of E+B field structure, monoenergetic protons have several unique advantages compared to the broad energy spectrum used in previous experiments. Recent experiments have been performed with a single laser beam (intensity of ∼1014W∕cm2) interacting with a CH foil, and B fields of ∼0.5MG and E fields of ∼1.5×108V∕m have been measured using proton deflectometry. LASNEX simulations are being used to interpret these experiments. Additional information will also be presented on the applicat...

The fast ignition (FI) concept requires the generation of a compact, dense, pure fuel mass accessible to an external ignition source. The current base line FI target is a shell fitted with a reentrant cone extending to near its center. Conventional direct- or indirect-drive collapses the shell near the tip of the cone and then an ultraintense laser pulse focused to the inside cone tip generates high-energy electrons to ignite the dense fuel. A theoretical and experimental investigation was undertaken of the collapse of such targets, validating modeling, and exploring the trade-offs available, in such an asymmetric geometry, to optimize compaction of the fuel and maintain the integrity of the cone. The collapse is complex. Away from the cone, the shell collapses much as does a conventional implosion, generating a hot, low-density inner core. But because of the open side, hot plasma exhausts out toward the tip of the cone. This hot plasma is advantageous for implosion diagnostics; it can provide protons for angular dependent measurements of the shell wall, neutrons for temperature measurements, and self-emission for contamination measurements. But for FI it is a liability; the hot, low-density inner core impedes the compaction of the cold fuel, lowering the implosion/burn efficiency and the gain. Approaches to optimizing this shell design are discussed.

Marshall Rosenbluth’s extensive contributions included seminal analysis of the physics of the laser-plasma interaction and review and advocacy of the inertial fusion program. Over the last decade he avidly followed the efforts of many scientists around the world who have studied Fast Ignition, an alternate form of inertial fusion. In this scheme, the fuel is first compressed by a conventional inertial confinement fusion driver and then ignited by a short (∼10ps) pulse, high-power laser. Due to technological advances, such short-pulse lasers can focus power equivalent to that produced by the hydrodynamic stagnation of conventional inertial fusion capsules. This review will discuss the ignition requirements and gain curves starting from simple models and then describe how these are modified, as more detailed physics understanding is included. The critical design issues revolve around two questions: How can the compressed fuel be efficiently assembled? And how can power from the driver be delivered efficient...

Measurements from three classes of direct-drive implosions at the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] were combined with Monte Carlo simulations to investigate models for determining hot-fuel areal density (ρRhot) in compressed, D2-filled capsules, and to assess the impact of mix and other factors on the determination of ρRhot. The results of the Monte Carlo simulations were compared to predictions of simple, commonly used models that use ratios of either secondary D3He proton yields or secondary DT neutron yields to primary DD neutron yields to provide estimates ρRhot,2p or ρRhot,2n, respectively, for ρRhot. For the first class of implosion, where ρRhot is low (⩽3 mg/cm2), ρRhot,2p and ρRhot,2n often agree with each other and are often good estimates of the actual ρRhot. For the second class of implosion, where ρRhot is of order 10 mg/cm2, ρRhot,2p often underestimates the actual value due to secondary proton yield saturation; in addition, fuel-shell mix causes ρRhot,2p...

Ion-acceleration processes have been studied in ultraintense laser plasma interactions for normal incidence irradiation of solid deuterated targets via neutron spectroscopy. The experimental neutron spectra strongly suggest that the ions are preferentially accelerated radially, rather than into the bulk of the material from three-dimensional Monte Carlo fitting of the neutron spectra. Although the laser system has a ${10}^{\ensuremath{-}7}$ contrast ratio, a two-dimensional magnetic hydrodynamics simulation shows that the laser pedestal generates a $10\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ scale length in the coronal plasma with a $3\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{m}$ scale-length plasma near the critical density. Two-dimensional particle-in-cell simulations, incorporating this realistic density profile, indicate that the acceleration of the ions is caused by a collisionless shock formation. This has implications for modeling energy transport in solid density plasmas as well as cone-focused fast ignition using the next generation PW lasers currently under construction.

The degradation in implosion performance of surface‐pitted, indirectly driven Br‐doped capsules which have been intentionally designed to be susceptible to large hydrodynamic instability growth has been systematically and reproducibly measured by a wide array of x‐ray and neutron diagnostics. Primary and secondary neutron yields, and x‐ray line ratios and durations from Ar and Ti fuel and pusher dopants are presented, showing clear sensitivity to increasing surface roughness and by inference, increasing pusher‐fuel mix. The sensitivity of core x‐ray emissivity and neutron bang‐times to micron variations in capsule ablator thickness is also demonstrated. The experimental trends are compared to expectations based on two different models for the effects of instability growth at the pusher‐fuel interface (atomic mixing versus Rayleigh–Taylor bubble‐and‐spike growth).

Measurements of the ratio of dt to dd neutrons from pure deuterium fuel have been used as a method for determination of fuel areal density (〈ρR〉). The relationship between fuel 〈ρR〉 and dt neutron production becomes uncertain for 〈ρR〉 values large enough that the 1.01‐MeV tritons from the d(d,t)p reaction lose a significant amount of energy in the fuel. A method based on neutron spectroscopy is described that improves the determination of fuel 〈ρR〉 in the region where tritons lose significant energy but have not yet thermalized. Charged particle stopping powers relevant to inertial confinement fusion ignition conditions may also be determined.

The paper presents infrared photometry of the RS CVn binary stars AR Lac (1.2-10 microns) and MM Her (1.2-3.5 microns) as they egressed from their primary and secondary eclipses; of the eclipsing systems RS CVn and Z Her at maximum light (1.2-10 microns) and of the non-eclipsing systems UX Ari and HR 1099 (1.2-10 microns). An analysis of these and published V data based on flux ratio diagrams (linear analogues of color-color diagrams) shows that G and K stars supply the infrared light of these systems. In AR Lac, the combined light of a G5-K0 subgiant and either a late F dwarf or an early F subgiant can account for the observed visual and infrared light curves. None of these systems shows infrared emission from circumstellar matter. This result is simply understood: dust grains would not be expected to form in the physical conditions surrounding the subgiant, and the corona and chromosphere (whose properties have been deduced from spectroscopic X-ray observations) should not produce appreciable infrared emission.

The Petawatt laser at Lawrence Livermore National Laboratory (LLNL) has opened a new regime of laser matter interactions in which the quiver motion of plasma electrons is fully relativistic with energies extending well above the threshold for nuclear processes. In addition to ∼few MeV ponderomotive electrons produced in ultra intense laser-solid interactions, we have found a high energy component of electrons extending to ∼100 MeV apparently from relativistic selffocusing and plasma acceleration in the underdense preformed plasma. The generation of hard bremsstrahlung, photonuclear reactions, and preliminary evidence for positron-electron pair production will be discussed.

Solid targets irradiated with 1019 W/cm2 or greater of 1 μm light in picosecond pulses are found to be radioactive. The strongest activities observed are the result of photonuclear reactions in which an energetic photon excites the nucleus sufficiently to produce particle emission leaving a radioactive daughter. The photoreaction cross sections are known for a wide range of nuclei and provide a quantitative measure of the photon flux produced in the target. Both the delayed daughter activities and measurements of the prompt particles emitted in the reaction can be used as diagnostics. Examples of these techniques applied in diagnosing experiments at the Nova laser facility adapted to generate petawatt pulses using chirped pulse amplification will be presented. These results will be compared with bremsstrahlung photon spectra calculated using electron spectra measured in a magnetic spectrograph.

THE detection of ∼ 100-MeV γ rays from Cyg X-3 has been reported from recently published SAS-2 data (R. C. Lamb et al.17). The γ-ray luminosity is ∼ 1037 erg s−1 assuming the source is ∼ 10 kpc distant. Cyg X-3 is well known as an X-ray and infrared source, and a source of non-thermal radio outbursts1 (Lx ∼ 1038, LIR ∼ 1037, Lradio ∼ 1033–1035 erg s−1). The infrared, X-ray and γ-ray fluxes all display a 4.8-h modulation in phase with one another1, which we shall presume to be attributable to binary motion2,3. We note here that inverse Compton scattering of ∼ 100 MeV relativistic electrons, in a region between the X-ray source and its companion, by the plentiful X rays, provides a mechanism for the γ-ray emission and its observed modulation.

We analyze the energetics of models for SS 433 which derive the large oscillatory Doppler shifts from the 164 day precession of a pair of oppositely directed beams. We propose that the beams power the emission lines (both shifted and unshifted), the compact X-ray source, and the radio source by dissipating a small fraction of their kinetic energy as they sweep through an ambient gaseous medium. An X-ray photoionization model fits the data well. The beams are also responsible for the elongated shape and filled-in structure of the extended radio source W50. From these two manifestations, we infer that the luminosity in kinetic energy in each beam exceeds 10/sup 40/ ergs s/sup -1/, five orders of magnitude greater than the H..cap alpha.. luminosity.

We show that a moderately massive disk (10/sup -5/--10/sup -2/ M/sub sun/) can cause the Lense-Thirring precession of the compact object (neutron star or black hole) at its center. The inner regions of the disk (r< or approx. =10/sup 8/ cm) align with the equator of an will precess at the same rate as the compact object. We propose that this disk-driven precession produces the 164 day period in SS 433. In our model, SS 433 represents a stage in the evolution of a binary X-ray source, containing a nondegenerate primary star, a compact companion, and an accretion disk about the compact object. A large rate of mass loss from the primary produces the moderately massive, supercritical accretion disk. The accretion luminosity, which greatly exceeds the Eddington limit, appears as kinetic energy of outflow of accreted material. The high accretion rate causes the inner disk to be thick; this toriodal inner disk collimates the outflow into two beams.

A series of direct drive implosions of D‐T filled, glass microballoons has been initiated in an effort to produce intense neutron sources for diagnostics development. In particular, measurements such as neutron imaging, burn history using a neutron‐sensitive streak camera, and fuel ρr by both neutron activation and neutron spectroscopy could be more easily tested with these simple targets than high‐density targets that initially are not expected to produce such high yields. Targets with nominal dimensions of 1000×2 μm which contained D‐T at 12–14 atm were imploded with 18 kJ of 0.35‐μm light from the 10‐beam Nova system. For pulse widths of 1 ns in either converging or diverging geometry, fusion yields in excess of 1013 have been obtained. The yields are comparable to those predicted from numerous 1‐D model calculations in spite of the asymmetric illumination geometry of the driver. Work performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under contract number W‐7405‐E...