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Background The immune-checkpoint inhibitors (ICIs) announced a new era in cancer treatment allowing long-term survival in advanced cancers. However, immune related adverse events impose treatment limitations being one of the main challenges when dealing with ICI treated patients. Neurologic toxicities have unique presentations and can progress rapidly, requiring prompt recognition. Among them, ICI-related peripheral nerve disorders are highly heterogeneous, profoundly debilitating, and insufficiently explored. Material and Methods We reviewed the clinical and electrodiagnostic features of a retrospective cohort of patients hospitalized in our centre for ICI related neuropathies. We applied the EFNS 2021 electrodiagnostic criteria for neuropathies and we researched the outcome according to the treatment received. Results We included 16 patients: 4 men and 12 women, median age 61 years (31-72) treated by anti-PD1 monotherapy (10) or antiCTLA4-antiPD1 combination (6). Median delay from ICIs initiation to neuropathy symptoms was 58,5 days (4 cycles), it seemed lower in combination group (median 33,5 days vs 81,5 days in monotherapy patients p=0,02). Half of patients presented with concurrent non-neurological irAE. CSF was inflammatory in 56% of cases, pleocytosis was seen in 57% of these. Cranial nerve involvement was rare (3/16) the most frequent phenotype was demyelinating polyneuropathy fulfilling EFNS 2021 EMG criteria in 10 cases. The other 6 presented with non-length dependent sensory neuropathy, (3) dysautonomic neuropathy (1) or sensory motor neuropathy with incomplete EFNS 2021 EMG criteria (2). ICI treatment was stopped, and steroids were the first line of treatment for all patients. However, 12/16 patients received additional iv immunoglobulin. Supplementary immunomodulation (cyclophosphamide, tocilizumab) was required in 2 cases. 75% of patients improved within a median of 4.5 months, median decrease in mRS was 2 points. Noteworthy, the rechallenge by antiPD1 monotherapy was proposed in 4 patients with a single neuropathy relapse. Conclusion Our series expand the knowledge on the clinical and electrophysiological phenotype of ICI related neuropathies improving their recognition in clinical practice. Moreover, our findings argue for the benefit of adding iv immunoglobulin to steroids as a first line treatment for different phenotypes of ICI related neuropathies.

We detail results of an experiment performed at the Ligne d'Intégration Laser facility aimed at studying supersonic and diffusive radiation front propagation in low-density SiO2 aerogel (20 and 40 mg/cm3) enclosed in a gold tube, driven by thermal emission from a laser-heated spherical gold cavity. The evolution of the front is studied continuously by measuring its self-emission with a 1D (one-dimensional) time-resolved soft x-ray imager. Measurement is performed along (through a 200- μm-wide observation slit) and at the exit of the tube giving access to the dynamics and the curvature of the front. Experimental results are then compared successfully to results from the 3D (three-dimensional) radiation hydrodynamics code TROLL, which shows that if continuous tracking of the front position is accessible with this experimental scheme, measurement of its maximum radiation temperature is on the contrary affected by radiation closure of the observation slit. 3D simulations also indicate that this effect can even be worsened if one includes pointing errors of the x-ray imager. Radiation temperature along the tube was then inferred by combining results from the imager to a wall shock breakout time measurement using a velocity interferometer system for any reflector and results from a broadband x-ray spectrometer used to determine the temperature at the exit of the tube. A decrease in the radiation temperature along the tube is observed, the decrease being more important for the higher SiO2 aerogel density.

International audience; We detail results of an experiment performed at the Laser Mégajoule (LMJ) facilityaimed at studying transition from supersonic radiation front to shock front in a lowdensity CHOBr foam enclosed in a plastic tube driven by thermal emission producedin a laser heated spherical gold cavity. Time resolved 2D hard x-ray radiographyimaging using a Sc source (photon energy at ~ 4.3 keV) is employed to measure thedensity perturbation front position, absorption, curvature and shocked materialcompression (defined as the compressed foam density normalized to its nominal value)from the supersonic to the subsonic regimes of propagation. Between these two regimeswhere compression goes from 1 (limited hydrodynamics) to 4 (strong shock formed), aquick increase of the foam compression is observed at the transition time tHS =6.75±0.75 ns, corresponding to the transient transonic regime (HS means“hydrodynamically separated” and refers to the instant when the shock and the radiationfront physically separate). This time is associated to a foam compression ratio of ~2and a Mach number of the slowing down front below M < 2. Experimental results aresuccessfully compared to 3D hydrodynamics simulations; comparisons never presentedfor that regime in past similar studies to our knowledge. Simulations show that thetransition time tHS is sensitive to the radiation closure of the tube entrance. This closure, which occurs in 3D, affects the amount of x-ray energy coupled from the laser heatedcavity to the CHOBr foam, and consequently the transient transonic regime dynamics.

We report on the performance of the highest radiant energy x-ray source at the LaserMegaJoule facility (LMJ) for testing material properties under irradiation. This radiation source was produced by the L-shell emission of xenon contained in a gas-pipe. The target was an epoxy ortho-cylinder tube with a diameter of 3 mm and a 50- μm thickness wall containing xenon gas at 1.2 atm. For this proof of principle shot, the LaserMegaJoule facility delivered a total energy of around 90 kJ of 351 nm laser and a total power of 30 TW. Thirty-two beams, divided into eight beamlets each, are arranged into two cones. The laser pulses were nearly flat, with a duration of 3 ns and a power range of 3.5–5 TW for each quadruplet. Two broadband spectrometers, DMX (DP4) and miniDMX (DP11), have been used to characterize the x-ray emission up to 10 keV. Radiant energy up to 0.5 kJ/sr has been recorded in the xenon L-shell band between 3 and 6 keV. This was the highest energy ever delivered for creating an x-ray source on the LMJ. Even though the target was axisymmetric, the strong asymmetric laser irradiation (nor axi or bottom/top symmetric) required full 3D radiation-hydrodynamic calculations to retrieve the radiant energy measured by broad band spectrometers. The main purpose of this work was to benchmark our 3D hydrorad code and the non-local thermodynamic equilibrium model by using newly developed x-ray spectrometers.

We report a laser-plasma experiment that was carried out at the LMJ-PETAL facility and realized the first magnetized, turbulent, supersonic plasma with a large magnetic Reynolds number ($\mathrm{Rm} \approx 45$) in the laboratory. Initial seed magnetic fields were amplified, but only moderately so, and did not become dynamically significant. A notable absence of magnetic energy at scales smaller than the outer scale of the turbulent cascade was also observed. Our results support the notion that moderately supersonic, low-magnetic-Prandtl-number plasma turbulence is inefficient at amplifying magnetic fields., 6 pages, 4 figures; supplemental information included (14 pages, 10 figures)

The effectiveness of a dome-shaped wall covered by a thin gold foil (hollow wall) [M. Vandenboomgaerde et al., Phys. Plasmas 25, 012713 (2018)PHPAEN1070-664X10.1063/1.5008669] in holding back the high-Z plasma expansion in a gas-filled hohlraum is demonstrated for the first time in experiments reproducing the irradiation conditions of indirect drive at the ignition scale. The setup exploits a 1D geometry enabling record of the complete history of the gold expansion for 8 ns by imaging its emission in multiple x-ray energy ranges featuring either the absorption zones or the thermal emission regions. The measured expansion dynamics is well reproduced by numerical simulations. This novel wall design could now be tailored for the megajoule scale to enable the propagation of the inner beams up to the equator in low gas-filled hohlraum thus allowing the fine-tuning of the irradiation symmetry on the timescale required for ignition.

The effectiveness of a dome-shaped wall covered by a thin gold foil (hollow wall) [M. Vandenboomgaerde et al., Phys. Plasmas 25, 012713 (2018)PHPAEN1070-664X10.1063/1.5008669] in holding back the high-Z plasma expansion in a gas-filled hohlraum is demonstrated for the first time in experiments reproducing the irradiation conditions of indirect drive at the ignition scale. The setup exploits a 1D geometry enabling record of the complete history of the gold expansion for 8 ns by imaging its emission in multiple x-ray energy ranges featuring either the absorption zones or the thermal emission regions. The measured expansion dynamics is well reproduced by numerical simulations. This novel wall design could now be tailored for the megajoule scale to enable the propagation of the inner beams up to the equator in low gas-filled hohlraum thus allowing the fine-tuning of the irradiation symmetry on the timescale required for ignition.

International audience; We present an experiment performed in 2016 at the LULI2000 laser facility in which X-ray and XUV absorption structures of nickel hot plasmas were measured simultaneously. Such experiments may provide stringent tests of the accuracy of plasma atomic-physics codes used to the modeling of plasmas close to local thermodynamic equilibrium. The experimental setup relies on a symmetric heating of the sample foil by two gold hohlraums in order to reduce the spatial gradients. The plasma conditions are characterized by temperatures between 10 and 20 eV and densities of the order of 10$^{−3}$ g/cm $^3$-10$^{−2}$ g/cm$^3$. For the X-ray part, we investigate the 2p-3d and 2p-4d transitions, and for the XUV part, we recorded the $\Delta$n = 0 (n = 3) transitions, which present a high sensitivity to plasma temperature. These latter transitions are of particular interest because, in mid-Z plasmas, they dominate the Planck and Rosseland mean opacities. Measured spectra are compared to calculations performed using the hybrid opacity code SCO-RCG and the Flexible Atomic Code (FAC). The influence of a spectator electron on the calculated spectra is analyzed using the latter code.

Implosion experiments of an inertial confinement fusion (ICF) target on the laser megajoule (LMJ) and the National Ignition Facility require, for certain designs, a precise timing coalescence of fo...

The advent of high-power lasers facilities such as the National Ignition Facility (NIF), and the Laser Megajoule (LMJ) in the near future, opens a new era in the field of High Energy Density Laboratory Astrophysics. These versatile laser facilities will provide unique platforms to study the rich physics of nonlinear and turbulent mixing flows. The extended laser pulse duration could be harnessed to accelerate targets over much larger distances and longer time periods than previously achieved. We report on the first results acquired on NIF with the ablative Rayleigh–Taylor Instability (RTI) platform. A 20-ns X-ray drive is tailored to accelerate planar modulated samples into the highly-nonlinear bubble merger regime. Based on the analogy between flames front and ablation front, highly nonlinear RTI measurements at ablation front can provide important insights into the initial deflagration stage of thermonuclear supernova of Type Ia. We also report on an innovative concept used to create even longer drive on multi-beam laser facilities. The multi-barrel hohlraum (Gattling Gun) approach consists, here, of three adjacent cavities, driven in succession in time. This novel concept has been validated on the Omega EP laser system. The three cavities were irradiated with three 6–10 ns pulse UV beams and a 30 ns, 90 eV X-ray radiation drive was measured with the time-resolved X-ray spectrometer μDMX. This concept is promising to investigate the pillar structures in the Eagle Nebula or for photoionization studies which require a steady light source of sufficient duration to recreate relevant physics.

The advent of high-power lasers facilities such as the National Ignition Facility (NIF), and Laser Megajoule (LMJ) in the near future opens a new era in the field of High Energy Density Laboratory Astrophysics. The LMJ, keystone of the French Simulation Program, is under construction at CEA/CESTA and will deliver 1.5 MJ with 176 beamlines. The first physics experiments on LMJ will be performed at the end of 2014 with 2 quadruplets (8 beams). The operational capabilities (number of beams and plasma diagnostics) will increase gradually during the following years. We describe the current status of the LMJ facility and the first set of diagnostics to be used during the commissioning phase and the first experiments. The PETAL project (PETawatt Aquitaine Laser), part of the CEA opening policy, consists in the addition of one short-pulse (500 fs to 10 ps) ultra-high-power, high-energy beam (a few kJ compressed energy) to the LMJ facility. PETAL is focalized into the LMJ target chamber and could be used alone or in combination with LMJ beams. In the later case, PETAL will offer a combination of a very high intensity multi-petawatt beam, synchronized with the nanosecond beams of the LMJ. PETAL, which is devoted to the academic research, will also extend the LMJ diagnostic capabilities. Specific diagnostics adapted to PETAL capacities are being fabricated in order to characterize particles and radiation yields that can be created by PETAL. A first set of diagnostics will measure the particles (protons/ions/electrons) spectrum (0.1–200 MeV range) and will also provide point projection proton-radiography capability. LMJ/PETAL, like previously the LIL laser [X. Julien et al., Proc. SPIE 7916 (2011) 791610], will be open to the academic community. Laboratory astrophysics experiments have already been performed on the LIL facility, as for example radiative shock experiments and planetary interiors equation of state measurements.

International audience; Ion stopping experiments in plasma for beam energies of few hundred keV per nucleon are of great interest to benchmark the stopping-power models in the context of inertial confinement fusion and high-energy-density physics research. For this purpose, a specific ion detector on chemical-vapor-deposition diamond basis has been developed for precise time-of-flight measurements of the ion energy loss. The electrode structure is interdigitated for maximizing its sensitivity to low-energy ions, and it has a finger width of 100 μm and a spacing of 500 μm. A short single α-particle response is obtained, with signals as narrow as 700 ps at full width at half maximum. The detector has been tested with α-particle bunches at a 500 keV per nucleon energy, showing an excellent time-of-flight resolution down to 20 ps. In this way, beam energy resolutions from 0.4 keV to a few keV have been obtained in an experimental configuration using a 100 μg/cm2 thick carbon foil as an energy-loss target and a 2 m time-of-flight distance. This allows a highly precise beam energy measurement of δE/E ≈ 0.04%–0.2% and a resolution on the energy loss of 0.6%–2.5% for a fine testing of stopping-power models.

A novel concept for using hybrid targets to create multi-keV X-ray sources was tested on the GEKKO XII facility of the OSAKA University and on the OMEGA facility of the University of Rochester. The sources were made via laser irradiation of a titanium foil placed at the end of a plastic cylinder, filled with a very low-density (2 and 5 mg/cm3) silicon-dioxide aerogel that was designed to control the longitudinal expansion of the titanium plasma. Preliminary calculations were used to determine optimal conditions for the aerogel density, cylinder diameter and length that maximize multi-keV X-ray emission. The X-ray emission power was measured on OMEGA using absolutely calibrated broad-band, diode-based CEA diagnostics, in addition to high resolution crystal spectrometers. On GEKKO XII, the heat wave propagation velocity in the aerogel was also measured with an X-ray framing camera. The advantage of using the thermal wave generated in the aerogel to heat a solid material to increase the conversion efficiency has not been fully demonstrated in these experiments. However, it was shown that a 5 mg/cm3 aerogel placed in front of a titanium foil can improve the x-ray conversion efficiency with respect to the case of 2 mg/cm3 for some target diameter and length.

Due to the iconic status of the pillars of the Eagle Nebula, this research will bring popular attention to plasma physics, HED laboratory physics, and fundamental science at NIF and other experimental facilities. The result will be to both to bring new perspectives to the studies of hydrodynamics in inertial confinement fusion and HED scenarios in general, and to promote interest in the STEM disciplines.

This research will; confirm the possibility of studying the structure and evolution of star-forming regions of molecular clouds in the laboratory; test the cometary model for the formation of the pillar structures in molecular clouds; assess the effect of magnetic fields on the evolution of structures in molecular clouds; and develop and demonstrate a new, long-duration (60-100 ns), directional source of x-ray radiation that can be used for the study of deeply nonlinear hydrodynamics, hydrodynamic instabilities that occur in the presence of directional radiation, shock-driven and radiatively-driven collapse of dense cores, and photoionization. Due to the iconic status of the pillars of the Eagle Nebula, this research will bring popular attention to plasma physics, HED laboratory physics, and fundamental science at NIF and other experimental facilities. The result will be to both to bring new perspectives to the studies of hydrodynamics in inertial confinement fusion and HED scenarios in general, and to promote interest in the STEM disciplines.

The time resolved crystal x-ray spectrometers called SXDHR-lt of the Ligne d’Integration laser is presented. It is necessary to calibrate all x-ray sensitive elements of diagnostics before using them in laser matter interaction experiments. In particular, crystals need to be calibrated. Measurements of the integrated coefficient of reflection of a beryl cylindrical crystal used in this spectrometer were performed with synchrotron radiation and with an x-ray tube and are presented. A test of the homogeneity of the reflection of the crystal was also performed. Aging or accidental pollution of x-ray diagnostics installed around target chambers is always possible. This happened to the DMX broadband spectrometer installed on the OMEGA Laser Facility at the University of Rochester (Laboratory for Laser Energetics) and this changed the spectral sensitivity of its channels. The evolution over time of the x-ray sensitivity needs to be critically assessed and if necessary x-ray sensitive elements will need to be recalibrated.

Introduction L’efficacite et la tolerance du facteur VII active recombinant (rFVIIa) sont reconnues chez les patients avec une hemophilie A acquise (HAA), mais des donnees detaillees sur le controle du saignement en pratique medicale sont limitees. Patients et methodes L’objectif de cette etude prospective, observationnelle, multicentrique, francaise (ACQUI-7) etait de renforcer les connaissances sur les differents types de saignements survenant chez des patients HAA (titre de l’auto-anticorps anti-FVIII > 1 UB ; taux de FVIII Les donnees ont ete collectees dans 20 centres de traitement de l’hemophilie ou departement de medecine interne entre 2010 et 2013. Apres inclusion pour prise en charge d’un episode hemorragique traite par rFVIIa en 1re ou 2nde intention, les patients etaient suivis pendant 1 an. Les modalites d’utilisation du rFVIIa etaient laissees au libre arbitre de l’investigateur. Resultats Vingt-sept patients (18 hommes), âges de 76 ans (± 14 DS) ont ete recrutes. Seize (59 %) patients avaient une HAA idiopathique, les autres avaient une pathologie associee possiblement liee a la survenue de HAA (5 une polyarthrite rhumatoide, 1 un lupus erythemateux systemique, 3 une pathologie tumorale active) et/ou des medicaments potentiellement inducteurs (betalactamines [2], clopidrogel [3]). Plus de la moitie des patients avaient une maladie ou des facteurs de risque cardiovasculaires. Vingt-sept saignements (89 % severes) ont ete traites avec rFVIIa, en premiere intention. Le saignement justifiant le traitement par rFVIIa etait musculaire (12), cutane (3), digestif (3), urinaire (2), pleural (2), retroperitoneal (2), oropharynge (1), articulaire (1) et post-extraction dentaire (1). Plus de 15 jours avant l’episode hemorragique a l’origine du diagnostic, 9 patients ont presente des saignements et principalement cutanes et/ou muqueux (7). Le delai median entre le diagnostic et le traitement etait de 1,5 jour. rFVIIa etait efficace dans 89 % des saignements. La dose initiale etait de 90,5 mg/kg [83,2 ; 100,0], la duree du traitement de 4 jours [2 ; 11] avec 12 [5 ; 21] injections et la dose cumulee de 0,90 mg/kg [0,48 ; 1,79] (mediane [Q1 ; Q3]). Le nombre median quotidien d’injections pendant les 4 premiers jours etait entre 2 et 3. L’utilisation du rFVIIa pour le traitement des saignements severes entre j1 (1er jour de traitement) et j4 sont presentees dans le Tableau 1 . Au cours du traitement, une modification de la dose et/ou frequence des injections etait realisee chez 19 patients avec une augmentation chez 6 patients et une diminution chez 16 patients. Aucun evenement indesirable grave, dont evenement thromboembolique, lie au rFVIIa n’a ete rapporte. Six deces sont survenus (septicemie, saignement, deterioration generale [1] , neoplasmes [1] ). Conclusion Ces donnees sont en accord avec celles des etudes EACH2, SACHA, pour le type de saignements traites et la prise en charge globale par rFVIIa (doses cumulees, nombre total d’injections, duree de traitement). ACQUI-7 apporte des informations complementaires sur l’utilisation quotidienne du rFVIIa dans l’hemophilie acquise.

X-ray transmission spectra of copper, nickel and aluminum laser produced plasmas were measured at the LULI2000 laser facility with an improved target design of indirect heating. Measurements were performed in plasmas close to local thermodynamic equilibrium at temperatures around 25 eV and densities between 10−3 g/cm3 and 10−2 g/cm3. This improved design provides several advantages, which are discussed in this paper. The sample is a thin foil of mid-Z material inserted between two gold cavities heated by two 300J, 2ω, nanosecond laser beams. A third laser beam irradiates a gold foil to create a spectrally continuous X-ray source (backlight) used to probe the sample. We investigate 2p–3d absorption structures in Ni and Cu plasmas as well as 1s–2p transitions in an additional Al plasma layer to infer the in-situ plasma temperature. Geometric and hydrodynamic calculations indicate that the improved geometry reduces spatial gradients during the transmission measurements. Experimental absorption spectra are in good agreement with calculations from the hybrid atomic physics code SCO-RCG.

This work describes measurements of laser propagation through very low-density aerogels and subsequent multi-keV photon production from titanium foils. For efficient foil heating, SiO 2 aerogel with densities of 2 and 5 mg/cm 3 have been cast into a plastic cylinder, which are then mounted to Ti foils that are 3–20 μm thick. Experiments have been performed on the GEKKO-XII laser facility to characterize laser propagation through the aerogel and X-ray production from the Ti foil. Multi-keV emission is diagnosed with a full set of diagnostics giving laser-to-X-ray conversion efficiencies, time-dependent X-ray power and two-dimensional X-ray imaging.

Dans le cadre du projet Simulation du CEA/DAM, l'acces experimental aux hautes densites d'energie et au domaine de la fusion thermonucleaire en Laboratoire se fera par le Laser Megajoules (LMJ) dont le prototype LIL est en cours de construction au CEA/CESTA pres de Bordeaux. Les programmes experimentaux correspondants ont necessite des performances elevees et le developpement d'une instrumentation de premier plan. C'est notamment le cas des diagnostics plasma qui ont evolue avec le developpement des lasers de puissance et celui des technologies adaptees pour etudier leur comportement. Le Service Diagnostics Experimentaux du CEA/Bruyeres-Le-Chatel developpe des diagnostics et integre la metrologie associee dans la conception de diagnostics. Nous presentons les moyens dont on dispose aupres du rayonnement synchrotron pour la metrologie des diagnostics et l'interet de cette metrologie pour l'etude des plasmas-laser.

In high flux (1013–15 W/cm2) laser-plasma interaction, a large part of the incoming laser energy is radiated into soft x-rays. To determine both the shape of this spectrum and the conversion efficiency, we have designed and tested an absolutely calibrated broadband soft x-ray spectrometer with a high temporal resolution (100 ps). The detector in this spectrometer is a new coaxial x-ray diode coupled with a fast single shot oscilloscope (French IN7100 with 7 GHz frequency response cutoff). Both absolute calibrations (x-ray response of diodes) and relative calibrations (filters and mirrors) have used the French synchrotron beam lines at Laboratoire pour l’utilisation du Rayonnement Electromagnetique (LURE) in Orsay. The initial version of this instrument was first successfully implemented on laser plasmas experiments at the Phebus facility in France and an improved version is now operating at the Omega laser facility in Rochester, New York. The emitted x-ray spectrum is absolutely measured in 18 broad bands...

The feasibility of efficient X-ray sources for radiography on the LMJ (Laser MegaJoule) in the multi-kJ/ns range was demonstrated on the OMEGA laser facility (Univ. Rochester) from 2002 to 2004 [1,2]. We significantly enhanced the conversion efficiency of titanium (4–6 keV), copper (8–10 keV) and germanium (9–13 keV) foils by using an optimized pre-pulse/pulse combination. Since higher X-ray energy and therefore electronic temperature need hydroconfinement, plastic cylindrical hohlraums internally coated with titanium, copper and germanium with various OMEGA beam configurations were successfully tested from 2005 to 2009 [3–5]. In addition, many shots with metal-doped aerogel (Ti, Fe, Ge) were tested on OMEGA [6].Recently we tested a new concept of “HYBRID sources” based on the combination of a thin titanium foil at the exit hole of a plastic cylinder filled with very low density SiO 2 aerogel (2 and 5 mg/cc). The benefit of the underdense medium is, first, to transport the laser energy to the titanium foil after its conversion into a supersonic ionization front and, second, to prevent foil expansion and excessive kinetic energy losses by longitudinal hydroconfinement.

In 2009 a series of metal-lined hohlraums were tested on the Omega laser facility. The main aims of the campaign were to improve our understanding of the multi-keV energy production and our capability to numerically reproduce the measured conversion efficiencies (CE's). Two studies have been primarily planned: the effect of the metallic plasma mean ionization states and that of hydrodynamics. Six targets were experimented for which the metallic materials (titanium, copper, germanium), the cavity diameter, and the irradiation energy were varied. Here we compare experimental and calculated results. The numerical simulations are performed with the 2D hydro-radiative code FCI2. For all the cavities, the measured multi-keV x-ray powers versus time are qualitatively well reproduced by the simulations, indicating that hohlraum hydrodynamics seems to be well calculated. But we have an underestimation by a factor of ∼2 for the calculated CEs versus experimental values for titanium and copper hohlraums. By contrast there is a good agreement between measurements and calculations for the germanium hohlraum. To explain these results, we have calculated off-line integrated emissivities for couples of (ρ, Te) values contributing to the multi-keV production with several non-local-thermal-equilibrium (NLTE) atomic physics models.

We use the LIL (Ligne d'Integration Laser ) facility to study the coalescence of two planar shocks in an indirectly-driven planar sample of polystyrene. This experiment represents the preliminary stage of the future shock-timing campaign for the Laser Megajoule (LMJ). The main objectives are to validate the experimental concept and to test the numerical simulations. We used a gold spherical hohlraum to convert into X-ray the 351 nm wavelength laser pulse and to initiate the two shocks in the sample. To access time resolved shock velocities and temperature, we used two rear-side diagnostics: a VISAR (Velocity Interferometer System for Any Reflection) working at two different wavelengths and a streaked optical self-emission diagnostic. We observed the coalesced shock, in good agreement with the numerical simulations. We also observed a loss of signal during the first nanoseconds probably due to sample heating from the hohlraum X-ray flux.

The international OPAC consortium consists of astrophysicists, plasma physicists and experimentalists who examine opacity calculations used in stellar physics that appear questionable and perform new calculations and laser experiments to understand the differences and improve the calculations. We report on iron and nickel opacities for envelopes of stars from 2 to 14 M ⊙ and deliver our first conclusions concerning the reliability of the used calculations by illustrating the importance of the configuration interaction and of the completeness of the calculations for temperatures around 15–27 eV.

International audience; A new channel of an X-ray broadband spectrometer has been developed for the 2 – 4 keV spectral range. It uses a spectral filtering by using a non-periodic multilayer mirror. This channel is composed by a filter, an aperiodic multilayer mirror and a detector. The design and realization of the optical coating mirror has been defined such as the reflectivity is above 8% in almost the entire bandwidth range 2 – 4 keV and lower than 2% outside. The mirror is optimized for working at 1.9° grazing incidence. The mirror is coated with a stack of 115 chromium / scandium (Cr / Sc) non-periodic layers, between 0.6 nm and 7.3 nm and a 3 nm thick top SiO2 layer to protect the stack from oxidization. To control thin thicknesses, we produced specific multilayer mirrors which consist on a superposition of two periodic Cr / Sc multilayers with the layer to calibrate in between. The mirror and subnanometric layers characterizations were made at the “Laboratoire Charles Fabry” (LCF) with a grazing incidence reflectometer working at 8.048 keV (Cu Kα radiation) and at the synchrotron radiation facility SOLEIL on the hard X-ray branch of the “Metrology” beamline. The reflectivity of the mirrors as a function of the photon energy was obtained in the Physikalisch Technische Bundesanstalt (PTB) laboratory at the synchrotron radiation facility Bessy II.

The structure and morphology of the Ag/MgO(001) interface have been investigated in situ by grazing incidence X-ray diffraction during the first stages of Ag deposition by molecular beam epitaxy. At the very beginning, Ag is perfectly registered, consisting of wide, one monolayer high platelets that cover half of the surface. The growth then proceeds in the form of islands, with Ag relaxation on surfaces. Finally, plastic relaxation occurs through a misfit dislocation network. The epitaxial site (on top of oxygen atoms) and interfacial distance are experimentally determined for the first time. Comparison with previous theoretical results on this model metal/insulator interface shows that the most recent ab initio calculations predict the correct interfacial structure.

At CEA/Bruyeres-le-Châtel (Service CEM), there are facilities to calibrate X-ray detectors from 200 eV to 100 keV, with an accuracy of 4% at high energies ( E > 3 keV). The source is the direct radiation from the X-ray tubes [C Kα (277 eV) to Ti KαKβ (4.51/4.93 keV)] or fluorescence emission from secondary targets [Mg Kα (1.25 keV) to U Kα (98 keV)]. In addition, calibrations are carried out with the synchrotron radiation of the Super-ACO storage ring (LURE-Orsay), by selecting the monoenergetic beams with a double crystal monochromator which is tunable between 0.8 and 8 keV. The resolution is better than 1 eV. This last tool is very useful in the study of the absorption edges of the detector compounds (for example, Si K-edge and Ar K-edge). Some examples are presented of results obtained between 1 and 50 keV, with special reference to high flux detectors such as gold photocathodes and silicon avalanche photodiodes. Thick silicon photodiodes (for the high energy range) were also calibrated.

En 2011, une campagne experimentale dediee a l'etude des sources X a eu lieu sur la LIL. Son objectif principal etait de mesurer l'energie X emise dans la bande K par des feuilles metalliques irradiees par le quadruplet LIL. Les materiaux utilises etaient le titane, le fer, le cuivre, le zinc et le germanium qui permettent de couvrir la gamme d'energie ∼ (4,7–10,5) keV pour les besoins radiographiques. Deux series de tirs, a des energies delivrees sur cible de ∼5 kJ et ∼10 kJ, ont ete realisees. Les premiers resultats experimentaux, ainsi que leur comparaison avec ceux de simulations effectuees avec le code d'hydrodynamique radiative FCI2, sont presentes.

A novel surface diffractometer devoted to structural studies of surfaces and interfaces by X-ray scattering is described. It is composed of a very precise goniometer, onto which different UHV chambers can be rapidly aligned and interchanged without breaking the vacuum, thus allowing a more efficient use of the synchrotron X-ray beam. Two UHV chambers have been designed, one for horizontal sample surface, and one for vertical sample surface. The latter is equipped with all necessary tools to prepare the surface and perform molecular beam epitaxy at the same time as surface X-ray scattering. Both allow one to reach very large out-of-plane momentum transfer values with high accuracy.

An x-ray grating spectrometer was built in order to measure opacities in the 50 eV to 250 eV spectral range with an average spectral resolution ⟨E/δE⟩ ∼ 50. It has been used at the LULI-2000 laser facility at Ecole Polytechnique (France) to measure the Δn = 0, n = 3 transitions of several elements with neighboring atomic number: Cr, Fe, Ni, and Cu in the same experimental conditions. Hence a spectrometer with a wide spectral range is required. This spectrometer features one line of sight looking through a heated sample at backlighter emission. It is outfitted with one toroidal condensing mirror and several flat mirrors cutting off higher energy photons. The spectral dispersion is obtained with a flatfield grating. Detection consists of a streak camera sensitive to soft x-ray radiation. Some experimental results showing the performance of this spectrometer are presented.

International audience; We have developed non-periodic Cr/Sc multilayer mirrors specifically designed to reflect energy photons between 2 and 4 keV with a pre-defined reflectivity profile. Furthermore, these mirrors have to work as filters in the 1-2 keV and 4-12 keV energy bandpass with a reflectivity as low as possible in these bandwidths. The mirrors were designed and optimized with the help of a commercial calculation code. Numerous combinations of layers have been investigated with two or three different materials in the multilayer. The interfacial effect, leading to thickness modifications, has been investigated. Layer thicknesses were accurately controlled, taking into account compaction effect at interfaces. The best results lead to non-periodic mirrors dedicated to work at 1.5° grazing incidence with a reflectivity above 15% in almost the entire energy range 2-4 keV and lower than 1% outside, except in the total reflection zone. The final choice of material was made from the experimental knowledge of corresponding layer deposited behavior. The multilayers have been deposited by magnetron sputtering. Grazing-incidence X-ray reflectance at 8.05 keV (0.154 nm) and at the Physikalisch-Technische Bundesanstalt laboratory (PTB) at the synchrotron radiation facility BESSY II in Berlin for X-ray reflectance over the whole range were used both in order to characterize the multilayers (thicknesses, complex indices, and roughnesses). The final results show good agreement with the requested reflectivity profile.

The concept of X-UV Lamellar Multilayer Amplitude Grating (LMAG) is introduced and a method of fabrication is given. Dynamical and kinematic theories of the diffraction by a LMAG are presented. Different applications of the LMAGs are considered. The first one is the achievement of a narrow bandpass multilayer monochromator for the X-UV domain. The second one is the reduction of specular background in the reflectivity curve of a multilayer structure. The third one is the polychromator system which allows one to split spatially and to perform a spectral sampling of a polychromatic beam. Finally we studied experimentally the behavior of an LMAG in conical mounting.

Metal/ceramic interfaces are used in various technologically important areas such as thin film technology, electronic packaging, composites, protective coatings, catalysis and the glass industry. The mechanical properties of these systems strongly depend on the defects at the interface such as misfit dislocations. The Ag/MgO interface has been chosen as a model of such interfaces. If one assumes first that Ag atoms preferentially bond with only one type of ion Mg or O, the 0-lattice theory predicts a misfit dislocation network which is a square array of edge dislocations 9.5 nm apart and aligned along (110) directions with 1/2 (110) Burgers vectors. Another geometry might be expected in the case of similar bond strength of Ag-O and Ag-Mg. In this case the points of best match produce a square array of 6.7 nm parallel to (100) directions with 1/2 (100) Burgers vectors. Recently Trampert et al. have observed dislocations at the Ag/MgO interface by High Resolution Transmission Microscopy (HRTEM). From observations at (100) cross sections they claim that the dislocation network is of the latter type (dislocation lines along (100)), arguing that the observed dislocations are equally spaced in this direction. But lattice images show only weakly localized end-on dislocations whichmore » could be the result of sample preparation. The (100) project of the Burgers vector is found to be 1/2(100), from which they infer that the misfit dislocations separate the regions where Ag is on O from those where Ag is on Mg. However the (100) Burgers vector projection is the same for the two networks. Therefore there is not yet clear evidence for the orientation of the dislocation network in this system. In an attempt to determine unambiguously the network orientation and Burgers vector, the authors present here a first study of the dislocation network at this interface using grazing incidence X-ray diffraction.« less

The projected atomic structure of the $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(0001)(\sqrt{31}\ifmmode\times\else\texttimes\fi{}\sqrt{31})R\ifmmode\pm\else\textpm\fi{}9\ifmmode^\circ\else\textdegree\fi{}$ reconstruction has been analyzed by means of the grazing incidence x-ray diffraction technique, which is not limited by the surface insulating character. It consists of two Al planes whose structure is close to that of metallic Al(111). This overlayer is rotationally reconstructed, is commensurate with the substrate, and displays strong nonlinear static distortion waves. This layer, oxygen depleted, explains why the surface properties are dramatically changed.

This paper deals with theoretical studies on the 2p-3d absorption in iron, nickel, and copper plasmas related to LULI2000 (Laboratoire pour l'Utilisation des Lasers Intenses, 2000J facility) measurements in which target temperatures were of the order of 20 eV and plasma densities were in the range 0.004-0.01 g/cm(3). The radiatively heated targets were close to local thermodynamic equilibrium (LTE). The structure of 2p-3d transitions has been studied with the help of the statistical superconfiguration opacity code SCO and with the fine-structure atomic physics codes HULLAC and FAC. A new mixed version of the sco code allowing one to treat part of the configurations by detailed calculation based on the Cowan's code RCG has been also used in these comparisons. Special attention was paid to comparisons between theory and experiment concerning the term features which cannot be reproduced by SCO. The differences in the spin-orbit splitting and the statistical (thermal) broadening of the 2p-3d transitions have been investigated as a function of the atomic number Z. It appears that at the conditions of the experiment the role of the term and configuration broadening was different in the three analyzed elements, this broadening being sensitive to the atomic number. Some effects of the temperature gradients and possible non-LTE effects have been studied with the help of the radiative-collisional code SCRIC. The sensitivity of the 2p-3d structures with respect to temperature and density in medium-Z plasmas may be helpful for diagnostics of LTE plasmas especially in future experiments on the Δn=0 absorption in medium-Z plasmas for astrophysical applications.

Nous decrivons les premiers diagnostics X developpes actuellement pour le LMJ. Ceux-ci sont principalement dedies a la qualification de l’installation (mesure de tache focale, controle du pointage et de l’equilibrage des faisceaux), mais egalement au diagnostic de la cavite, du transfert radiatif (mesure de rendement de conversion X), au diagnostic de l’hydrodynamique (experiences de radiographie d’instabilites hydrodynamiques) et a l’imagerie de microballons DT. Ce premier lot de diagnostics comprend deux systemes de multi imagerie X bidimensionnelle associes a un tube obturateur et un systeme d’imagerie monodimensionnelle avec une camera a balayage de fente. Ces trois systemes d’imagerie X appeles « imageurs X » mesurent le rayonnement dans le domaine [500 eV–15 keV]. Un diagnostic de spectrometrie X large bande fonctionnant dans le domaine [30 eV–20 keV] est egalement developpe. Le design des diagnostics prend en compte les problematiques de vulnerabilite aux produits de tirs, de durcissement aux X-durs, gammas et neutrons, de contamination au tritium. Les contraintes liees a l’exploitation sont egalement considerees puisque l’intervention humaine au sein des diagnostics doit etre limitee au cours d’une campagne d’experiences. Les concepts retenus pour ces diagnostics sont presentes, de meme que la caracterisation d’une premiere maquette de microscope de multi imagerie X.

We present here an experimental study of the growth of Re/W(110). Auger electron spectroscopy, core level photoelectron spectroscopy and LEED experiments at T = 500 K and as a function of Re coverage θ show first (θ < 0.5 ML) a surface reconstruction followed (θ ≈ 1 ML) by formation of a two-layer surface alloy which is then buried by additional Re-layers (θ ≈ 3 ML). An empirical model is developed to simulate the growth mode. The main effect of annealing is to increase the number of Re-enriched layers. The establishment of a surface alloy over several atomic layers introduces the new idea of local equilibrium. Finally, the extension to non equilibrium situations of the usual thermodynamical Born-Haber cycle allowed us to derive from the KTBIM the time-evolution of the W4f core level spectra and shifts in good agreement with the experimental data.

We study here the relation between the surface segregation at thermodynamical equilibrium in an alloy AcB1−c and the kinetics of either segregation in the system A-B or dissolution of AB or BA. This is possible within a new kinetic model based on the electronic structure: the kinetic tight-binding Ising model (KTBIM). In particular, the existence of a local equilibrium between the surface and the first underlayer is stressed. Some illustrations are given in the particular case of the W-Re system.

The x-ray broadband spectrometer, DMX, is among the first plasma diagnostics to be deployed on Laser Megajoule (LMJ). The emitted x-ray spectrum from laser-produced plasmas is measured in 20 channels from 50 eV up to 20 keV. Each band combines mirrors and filters which realize x-ray band-pass filter and a coaxial diode coupled by a coaxial cable with a fast digitizer that realize the acquisition. The measurement accuracy depends on the equipment performance and the spectrum to acquire. In this context, Commissariat a l'Energie Atomique (CEA) is developing a numerical method called Acquisition Channel Simulator (ACS) whose purpose is to define and optimize all electrical acquisition channels of such diagnostics. The ACS goals are to define numerical model for each element the electrical channel and optimize it. This paper introduces the work led by CEA regarding the development of the ACS method particularly for the equipment model and the first results for the DMX diagnostic.

This Letter presents first experimental results of the laser imprint reduction in fusion scale plasmas using a low-density foam layer. The experiments were conducted on the LIL facility at the energy level of 12 kJ with millimeter-size plasmas, reproducing the conditions of the initial interaction phase in the direct-drive scheme. The results include the generation of a supersonic ionization wave in the foam and the reduction of the initial laser fluctuations after propagation through 500 {mu}m of foam with limited levels of stimulated Brillouin and Raman scattering. The smoothing mechanisms are analyzed and explained.

In contrast to what is commonly accepted, electronic structure calculations show that the core levels (S1, S2) associated with the surface and first underlayer atoms can be displaced in opposite directions in energy with respect to the bulk level (B). This is fully confirmed by experiments performed on the 4f 7 2 level of the Ir(100) surface, both in the unreconstructed (1 × 1) and reconstructed (5 × 1) case.

Surface EXAFS is used to determine the crystallographic structure of iron films prepared by deposition on Cu(100). These metastable films have structural and vibrational properties strongly dependent on their thickness and on their growth temperature. A well defined fee structure is obtained in films grown at a temperature higher than 350 K and in thick films (8 monolayers) grown at room temperature. The thinner films (2 to 5 monolayers) grown at room temperature do not have an fee structure: the first shell radial distribution function is very broad and anisotropic. The origin of this first shell broadening can be random static disorder in the layer or a well defined reconstruction inducing different nearest neighbour distances. These different crystallographic structures are apparently connected to the different magnetic properties measured in these films.

The knowledge of the crystallography of metastable cobalt and iron films prepared by deposition on suitable substrates is the key for the understanding of their unusual magnetic properties; their local structure is determined precisely by SEXAFS. This technique allows a measure of the asymmetry of the first shell radial distribution function in monometallic cobalt and iron films prepared by vapor condensation on a low temperature amorphous substrate. In both cases the measured profile allows to conclude the existence of true amorphous monometallic samples and compares well with the calculated one assuming a random packing of hard spheres. Following the evolution of the local order with increasing temperature we show that the cobalt amorphous films crystallize abruptly at a temperature dependent on their thickness, while the iron amorphous films crystallize slowly. Moreover EXAFS has been used to investigate the local structure of f.c.c. iron films which have puzzling magnetic properties. These metastable films grown on Cu(100) have a structure strongly dependent on their temperature of growth: Both the short range order and the amplitude of the thermal vibrations measured at room temperature are higher in films prepared at higher temperatures. These different crystallographic structures can be the origin of the conflicting results produced in the study of their magnetic properties.