Dimitri Khaghani

All Publications

• Multi-frame, ultrafast, x-ray microscope for imaging shockwave dynamics. Optics express Hodge, D. S., Leong, A. F., Pandolfi, S., Kurzer-Ogul, K., Montgomery, D. S., Aluie, H., Bolme, C., Carver, T., Cunningham, E., Curry, C. B., Dayton, M., Decker, F., Galtier, E., Hart, P., Khaghani, D., Ja Lee, H., Li, K., Liu, Y., Ramos, K., Shang, J., Vetter, S., Nagler, B., Sandberg, R. L., Gleason, A. E. 2022; 30 (21): 38405-38422

  Abstract

  Inertial confinement fusion (ICF) holds increasing promise as a potential source of abundant, clean energy, but has been impeded by defects such as micro-voids in the ablator layer of the fuel capsules. It is critical to understand how these micro-voids interact with the laser-driven shock waves that compress the fuel pellet. At the Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS), we utilized an x-ray pulse train with ns separation, an x-ray microscope, and an ultrafast x-ray imaging (UXI) detector to image shock wave interactions with micro-voids. To minimize the high- and low-frequency variations of the captured images, we incorporated principal component analysis (PCA) and image alignment for flat-field correction. After applying these techniques we generated phase and attenuation maps from a 2D hydrodynamic radiation code (xRAGE), which were used to simulate XPCI images that we qualitatively compare with experimental images, providing a one-to-one comparison for benchmarking material performance. Moreover, we implement a transport-of-intensity (TIE) based method to obtain the average projected mass density (areal density) of our experimental images, yielding insight into how defect-bearing ablator materials alter microstructural feature evolution, material compression, and shock wave propagation on ICF-relevant time scales.

  View details for DOI 10.1364/OE.472275

  View details for PubMedID 36258406

• Novel fabrication tools for dynamic compression targets with engineered voids using photolithography methods REVIEW OF SCIENTIFIC INSTRUMENTS Pandolfi, S., Carver, T., Hodge, D., Leong, A. T., Kurzer-Ogul, K., Hart, P., Galtier, E., Khaghani, D., Cunningham, E., Nagler, B., Lee, H., Bolme, C., Ramos, K., Li, K., Liu, Y., Sakdinawat, A., Marchesini, S., Kozlowski, P. M., Curry, C. B., Decker, F., Vetter, S., Shang, J., Aluie, H., Dayton, M., Montgomery, D. S., Sandberg, R. L., Gleason, A. E. 2022; 93 (10)

  View details for DOI 10.1063/5.0107542

  View details for Web of Science ID 000869134800001

• Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction. Science advances He, Z., Rodel, M., Lutgert, J., Bergermann, A., Bethkenhagen, M., Chekrygina, D., Cowan, T. E., Descamps, A., French, M., Galtier, E., Gleason, A. E., Glenn, G. D., Glenzer, S. H., Inubushi, Y., Hartley, N. J., Hernandez, J., Heuser, B., Humphries, O. S., Kamimura, N., Katagiri, K., Khaghani, D., Lee, H. J., McBride, E. E., Miyanishi, K., Nagler, B., Ofori-Okai, B., Ozaki, N., Pandolfi, S., Qu, C., Ranjan, D., Redmer, R., Schoenwaelder, C., Schuster, A. K., Stevenson, M. G., Sueda, K., Togashi, T., Vinci, T., Voigt, K., Vorberger, J., Yabashi, M., Yabuuchi, T., Zinta, L. M., Ravasio, A., Kraus, D. 2022; 8 (35): eabo0617

  Abstract

  Extreme conditions inside ice giants such as Uranus and Neptune can result in peculiar chemistry and structural transitions, e.g., the precipitation of diamonds or superionic water, as so far experimentally observed only for pure C─H and H2O systems, respectively. Here, we investigate a stoichiometric mixture of C and H2O by shock-compressing polyethylene terephthalate (PET) plastics and performing in situ x-ray probing. We observe diamond formation at pressures between 72 ± 7 and 125 ± 13 GPa at temperatures ranging from ~3500 to ~6000 K. Combining x-ray diffraction and small-angle x-ray scattering, we access the kinetics of this exotic reaction. The observed demixing of C and H2O suggests that diamond precipitation inside the ice giants is enhanced by oxygen, which can lead to isolated water and thus the formation of superionic structures relevant to the planets' magnetic fields. Moreover, our measurements indicate a way of producing nanodiamonds by simple laser-driven shock compression of cheap PET plastics.

  View details for DOI 10.1126/sciadv.abo0617

  View details for PubMedID 36054354

• Towards performing high-resolution inelastic X-ray scattering measurements at hard X-ray free-electron lasers coupled with energetic laser drivers JOURNAL OF SYNCHROTRON RADIATION Descamps, A., Ofori-Okai, B. K., Baldwin, J. K., Chen, Z., Fletcher, L. B., Glenzer, S. H., Hartley, N. J., Hasting, J. B., Khaghani, D., Mo, M., Nagler, B., Recoules, Redmer, R., Schoerner, M., Sun, P., Wang, Y. Q., White, T. G., McBride, E. E. 2022; 29: 931-938

  Abstract

  High-resolution inelastic X-ray scattering is an established technique in the synchrotron community, used to investigate collective low-frequency responses of materials. When fielded at hard X-ray free-electron lasers (XFELs) and combined with high-intensity laser drivers, it becomes a promising technique for investigating matter at high temperatures and high pressures. This technique gives access to important thermodynamic properties of matter at extreme conditions, such as temperature, material sound speed, and viscosity. The successful realization of this method requires the acquisition of many identical laser-pump/X-ray-probe shots, allowing the collection of a sufficient number of photons necessary to perform quantitative analyses. Here, a 2.5-fold improvement in the energy resolution of the instrument relative to previous works at the Matter in Extreme Conditions (MEC) endstation, Linac Coherent Light Source (LCLS), and the High Energy Density (HED) instrument, European XFEL, is presented. Some aspects of the experimental design that are essential for improving the number of photons detected in each X-ray shot, making such measurements feasible, are discussed. A careful choice of the energy resolution, the X-ray beam mode provided by the XFEL, and the position of the analysers used in such experiments can provide a more than ten-fold improvement in the photometrics. The discussion is supported by experimental data on 10 µm-thick iron and 50 nm-thick gold samples collected at the MEC endstation at the LCLS, and by complementary ray-tracing simulations coupled with thermal diffuse scattering calculations.

  View details for DOI 10.1107/S1600577522004453

  View details for Web of Science ID 000824201700001

  View details for PubMedID 35787558

  View details for PubMedCentralID PMC9255572

• Role of relativistic laser intensity on isochoric heating of metal wire targets OPTICS EXPRESS Martynenko, A. S., Pikuz, S. A., Antonelli, L., Barbato, F., Boutoux, G., Giuffrida, L., Honrubia, J. J., Hume, E., Jacoby, J., Khaghani, D., Lancaster, K., Neumayer, P., Rosmej, O. N., Santos, J. J., Turianska, O., Batani, D. 2021; 29 (8): 12240-12251

  Abstract

  In a recent experimental campaign, we used laser-accelerated relativistic hot electrons to ensure heating of thin titanium wire targets up to a warm dense matter (WDM) state [EPL114, 45002 (2016)10.1209/0295-5075/114/45002]. The WDM temperature profiles along several hundred microns of the wire were inferred by using spatially resolved X-ray emission spectroscopy looking at the Ti Kα characteristic lines. A maximum temperature of ∼30 eV was reached. Our study extends this work by discussing the influence of the laser parameters on temperature profiles and the optimisation of WDM wire-based generation. The depth of wire heating may reach several hundreds of microns and it is proven to be strictly dependent on the laser intensity. At the same time, it is quantitatively demonstrated that the maximum WDM temperature doesn't appear to be sensitive to the laser intensity and mainly depends on the deposited laser energy considering ranges of 6×1018-6×1020 W/cm2 and 50-200 J.

  View details for DOI 10.1364/OE.415091

  View details for Web of Science ID 000640033600072

  View details for PubMedID 33984988

• X-ray spectroscopy evidence for plasma shell formation in experiments modeling accretion columns in young stars MATTER AND RADIATION AT EXTREMES Filippov, E. D., Skobelev, I., Revet, G., Chen, S. N., Khiar, B., Ciardi, A., Khaghani, D., Higginson, D. P., Pikuz, S. A., Fuchs, J. 2019; 4 (6)

  View details for DOI 10.1063/1.5124350

  View details for Web of Science ID 000512299700005

• Properties of laser-driven hard x-ray sources over a wide range of laser intensities PHYSICS OF PLASMAS Borm, B., Khaghani, D., Neumayer, P. 2019; 26 (2)

  View details for DOI 10.1063/1.5081800

  View details for Web of Science ID 000460094400059

• Generation of keV hot near-solid density plasma states at high contrast laser-matter interaction PHYSICS OF PLASMAS Rosmej, O. N., Samsonova, Z., Hoefer, S., Kartashov, D., Arda, C., Khaghani, D., Schoenlein, A., Zaehter, S., Hoffmann, A., Loetzsch, R., Saevert, A., Uschmann, I., Povarnitsyn, M. E., Andreev, N. E., Pugachev, L. P., Kaluza, M. C., Spielmann, C. 2018; 25 (8)

  View details for DOI 10.1063/1.5027463

  View details for Web of Science ID 000443730900081

• Enhancement of Quasistationary Shocks and Heating via Temporal Staging in a Magnetized Laser-Plasma Jet PHYSICAL REVIEW LETTERS Higginson, D. P., Khiar, B., Revet, G., Beard, J., Blecher, M., Borghesi, M., Burdonov, K., Chen, S. N., Filippov, E., Khaghani, D., Naughton, K., Pepin, H., Pikuz, S., Portugall, O., Riconda, C., Riquier, R., Rodriguez, R., Ryazantsev, S. N., Skobelev, I., Soloviev, A., Starodubtsev, M., Vinci, T., Willi, O., Ciardi, A., Fuchs, J. 2017; 119 (25): 255002

  Abstract

  We investigate the formation of a laser-produced magnetized jet under conditions of a varying mass ejection rate and a varying divergence of the ejected plasma flow. This is done by irradiating a solid target placed in a 20 T magnetic field with, first, a collinear precursor laser pulse (10^{12}  W/cm^{2}) and, then, a main pulse (10^{13}  W/cm^{2}) arriving 9-19 ns later. Varying the time delay between the two pulses is found to control the divergence of the expanding plasma, which is shown to increase the strength of and heating in the conical shock that is responsible for jet collimation. These results show that plasma collimation due to shocks against a strong magnetic field can lead to stable, astrophysically relevant jets that are sustained over time scales 100 times the laser pulse duration (i.e., >70  ns), even in the case of strong variability at the source.

  View details for DOI 10.1103/PhysRevLett.119.255002

  View details for Web of Science ID 000418619100008

  View details for PubMedID 29303310

• Laboratory unraveling of matter accretion in young stars SCIENCE ADVANCES Revet, G., Chen, S. N., Bonito, R., Khiar, B., Filippov, E., Argiroffi, C., Higginson, D. P., Orlando, S., Beard, J., Blecher, M., Borghesi, M., Burdonov, K., Khaghani, D., Naughton, K., Pepin, H., Portugall, O., Riquier, R., Rodriguez, R., Ryazantsev, S. N., Skobelev, I., Soloviev, A., Willi, O., Pikuz, S., Ciardi, A., Fuchs, J. 2017; 3 (11): e1700982

  Abstract

  Accretion dynamics in the formation of young stars is still a matter of debate because of limitations in observations and modeling. Through scaled laboratory experiments of collimated plasma accretion onto a solid in the presence of a magnetic field, we open a first window on this phenomenon by tracking, with spatial and temporal resolution, the dynamics of the system and simultaneously measuring multiband emissions. We observe in these experiments that matter, upon impact, is ejected laterally from the solid surface and then refocused by the magnetic field toward the incoming stream. This ejected matter forms a plasma shell that envelops the shocked core, reducing escaped x-ray emission. This finding demonstrates one possible structure reconciling current discrepancies between mass accretion rates derived from x-ray and optical observations, respectively.

  View details for DOI 10.1126/sciadv.1700982

  View details for Web of Science ID 000418002000015

  View details for PubMedID 29109974

  View details for PubMedCentralID PMC5665592

• Enhancing laser-driven proton acceleration by using micro-pillar arrays at high drive energy SCIENTIFIC REPORTS Khaghani, D., Lobet, M., Borm, B., Burr, L., Gaertner, F., Gremillet, L., Movsesyan, L., Rosmej, O., Toimil-Molares, M., Wagner, F., Neumayer, P. 2017; 7: 11366

  Abstract

  The interaction of micro- and nano-structured target surfaces with high-power laser pulses is being widely investigated for its unprecedented absorption efficiency. We have developed vertically aligned metallic micro-pillar arrays for laser-driven proton acceleration experiments. We demonstrate that such targets help strengthen interaction mechanisms when irradiated with high-energy-class laser pulses of intensities ~1017-18 W/cm2. In comparison with standard planar targets, we witness strongly enhanced hot-electron production and proton acceleration both in terms of maximum energies and particle numbers. Supporting our experimental results, two-dimensional particle-in-cell simulations show an increase in laser energy conversion into hot electrons, leading to stronger acceleration fields. This opens a window of opportunity for further improvements of laser-driven ion acceleration systems.

  View details for DOI 10.1038/s41598-017-11589-z

  View details for Web of Science ID 000410297900080

  View details for PubMedID 28900164

  View details for PubMedCentralID PMC5596005

• Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle HIGH ENERGY DENSITY PHYSICS Higginson, D. P., Revet, G., Khiar, B., Beard, J., Blecher, M., Borghesi, M., Burdonov, K., Chen, S. N., Filippov, E., Khaghani, D., Naughton, K., Pepin, H., Pikuz, S., Portugall, O., Riconda, C., Riquier, R., Ryazantsev, S. N., Skobelev, I., Soloviev, A., Starodubtsev, M., Vinci, T., Willi, O., Ciardi, A., Fuchs, J. 2017; 23: 48-59

  View details for DOI 10.1016/j.hedp.2017.02.003

  View details for Web of Science ID 000404314500007

• X-Ray Emission Generated By Laser-Produced Plasmas From Dielectric Nanostructured Targets Samsonova, Z., Hoefer, S., Hoffmann, A., Landgraf, B., Zuerch, M., Uschmann, I., Khaghani, D., Rosmej, O., Neumayer, P., Roeder, R., Trefflich, L., Ronning, C., Foerster, E., Spielmann, C., Kartashov, D., Benredjem, D. AMER INST PHYSICS. 2017

  View details for DOI 10.1063/1.4975743

  View details for Web of Science ID 000404402600032

• X-Ray Emission of Exotic Ions in Dense Plasmas Rosmej, F. B., Khaghani, D., Dozieres, M., Dachicourt, R., Smid, M., Renner, O., Benredjem, D. AMER INST PHYSICS. 2017

  View details for DOI 10.1063/1.4975755

  View details for Web of Science ID 000404402600044

• Improvement of density resolution in short-pulse hard x-ray radiographic imaging using detector stacks REVIEW OF SCIENTIFIC INSTRUMENTS Borm, B., Gaertner, F., Khaghani, D., Neumayer, P. 2016; 87 (9): 093104

  Abstract

  We demonstrate that stacking several imaging plates (IPs) constitutes an easy method to increase hard x-ray detection efficiency. Used to record x-ray radiographic images produced by an intense-laser driven hard x-ray backlighter source, the IP stacks resulted in a significant improvement of the radiograph density resolution. We attribute this to the higher quantum efficiency of the combined detectors, leading to a reduced photon noise. Electron-photon transport simulations of the interaction processes in the detector reproduce the observed contrast improvement. Increasing the detection efficiency to enhance radiographic imaging capabilities is equally effective as increasing the x-ray source yield, e.g., by a larger drive laser energy.

  View details for DOI 10.1063/1.4961666

  View details for Web of Science ID 000385634500005

  View details for PubMedID 27782594

• Generation and characterization of warm dense matter isochorically heated by laser-induced relativistic electrons in a wire target EPL Schoenlein, A., Boutoux, G., Pikuz, S., Antonelli, L., Batani, D., Debayle, A., Franz, A., Giuffrida, L., Honrubia, J. J., Jacoby, J., Khaghani, D., Neumayer, P., Rosmej, O. N., Sakaki, T., Santos, J. J., Sauteray, A. 2016; 114 (4)

  View details for DOI 10.1209/0295-5075/114/45002

  View details for Web of Science ID 000379524100013

• K-shell spectroscopic diagnosis of suprathermal electrons at fusion-relevant environmental conditions Renner, O., Smid, M., Khaghani, D., Rosmej, F. B., IOP IOP PUBLISHING LTD. 2016

  View details for DOI 10.1088/1742-6596/688/1/012091

  View details for Web of Science ID 000376159100091

• Parameters of supersonic astrophysically-relevant plasma jets collimating via poloidal magnetic field measured by x-ray spectroscopy method Filippov, E. D., Pikuz, S. A., Skobelev, I., Ryazantsev, S. N., Higginson, D. P., Khaghani, D., Revet, G., Chen, S. N., Fuchs, J., IOP IOP PUBLISHING LTD. 2016

  View details for DOI 10.1088/1742-6596/774/1/012114

  View details for Web of Science ID 000403483200115

• X-ray opacity measurements in mid-Z dense plasmas with a new target design of indirect heating HIGH ENERGY DENSITY PHYSICS Dozieres, M., Thais, F., Bastiani-Ceccotti, S., Blenski, T., Fariaut, J., Foelsner, W., Gilleron, F., Khaghani, D., Pain, J., Reverdin, C., Rosmej, F., Silvert, V., Soullie, G., Villette, B. 2015; 17: 231-239

  View details for DOI 10.1016/j.hedp.2015.08.001

  View details for Web of Science ID 000366573000002

• Exotic x-ray emission from dense plasmas JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS Rosmej, F. B., Dachicourt, R., Deschaud, B., Khaghani, D., Dozieres, M., Smid, M., Renner, O. 2015; 48 (22)

  View details for DOI 10.1088/0953-4075/48/22/224005

  View details for Web of Science ID 000362459800006

• Electron-ion temperature equilibration in warm dense tantalum HIGH ENERGY DENSITY PHYSICS Hartley, N. J., Belancourt, P., Chapman, D. A., Doeppner, T., Drake, R. P., Gericke, D. O., Glenzer, S. H., Khaghani, D., Lepape, S., Ma, T., Neumayer, P., Pak, A., Peters, L., Richardson, S., Vorberger, J., WHITE, T. G., Gregori, G. 2015; 14: 1-5

  View details for DOI 10.1016/j.hedp.2014.10.003

  View details for Web of Science ID 000353331800001

• Developments toward hard X-ray radiography on heavy-ion heated dense plasmas LASER AND PARTICLE BEAMS Li, K., Borm, B., Hug, F., Khaghani, D., Loether, B., Savran, D., Tahir, N. A., Neumayer, P. 2014; 32 (4): 631-637

  View details for DOI 10.1017/S0263034614000652

  View details for Web of Science ID 000345447500017

• Investigation of x-ray emission induced by hot electrons in dense Cu plasmas Smid, M., Renner, O., Rosmej, F. B., Khaghani, D. IOP PUBLISHING LTD. 2014

  View details for DOI 10.1088/0031-8949/2014/T161/014020

  View details for Web of Science ID 000339620200021