Dimitri Khaghani
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View article: Ultrafast structural dynamics of silicate glasses in extreme environments
Ultrafast structural dynamics of silicate glasses in extreme environments Open
A fundamental understanding of network structure and associated atomic-scale mechanisms in silicate glasses under dynamic compression is crucial for explaining several phenomena including, planetary formation, core-mantle boundary dynamics…
View article: Measurement of turbulent velocity and bounds for thermal diffusivity in laser shock compressed foams by x-ray photon correlation spectroscopy
Measurement of turbulent velocity and bounds for thermal diffusivity in laser shock compressed foams by x-ray photon correlation spectroscopy Open
Experimental benchmarking of transport coefficients under extreme conditions is required for validation of differing theoretical models. To date, measurement of transport properties of dynamically compressed samples remains a challenge wit…
View article: Superheating gold beyond the predicted entropy catastrophe threshold
Superheating gold beyond the predicted entropy catastrophe threshold Open
In their landmark study1, Fecht and Johnson unveiled a phenomenon that they termed the 'entropy catastrophe', a critical point where the entropy of superheated crystals equates to that of their liquid counterparts. This point marks the upp…
View article: Characterizing laser-heated polymer foams with simultaneous x-ray fluorescence spectroscopy and Thomson scattering at the Matter in Extreme Conditions Endstation at LCLS
Characterizing laser-heated polymer foams with simultaneous x-ray fluorescence spectroscopy and Thomson scattering at the Matter in Extreme Conditions Endstation at LCLS Open
Understanding the behavior of polymer foams at high energy density conditions is crucial to advance inertial fusion energy research. Here, we present a new experimental platform designed to measure the thermodynamic state of these material…
View article: X-ray microscopy and talbot imaging with the matter in extreme conditions X-ray imager at LCLS
X-ray microscopy and talbot imaging with the matter in extreme conditions X-ray imager at LCLS Open
The last decade has shown the great potential that X-ray Free Electron Lasers (FEL) have to study High Energy Density (HED) physics. Experiments at FELs have made significant breakthroughs in Shock Physics and Dynamic Diffraction, Dense Pl…
View article: Stability of the fcc phase in shocked nickel up to 332 GPa
Stability of the fcc phase in shocked nickel up to 332 GPa Open
Despite making up 5–20 wt.% of Earth's predominantly iron core, the melting properties of elemental nickel at core conditions remain poorly understood, due largely to a dearth of experimental data. We present an in situ X-ray diffraction s…
View article: Ultrafast structural dynamics of doped silicate glasses in extreme environments
Ultrafast structural dynamics of doped silicate glasses in extreme environments Open
Composition and network structure of doped silicate glasses can strongly dictate the material properties including dynamic behavior in extreme conditions. The fundamental understanding of the role of network structure and related atomic-sc…
View article: Combined speckle- and propagation-based single shot two-dimensional phase retrieval method
Combined speckle- and propagation-based single shot two-dimensional phase retrieval method Open
Single-shot two-dimensional (2D) phase retrieval (PR) can recover the phase shift distribution within an object from a single 2D x-ray phase contrast image (XPCI). Two competing XPCI imaging modalities often used for single-shot 2D PR to r…
View article: Imaging material yielding and phase transitions in shock-compressed matter.
Imaging material yielding and phase transitions in shock-compressed matter. Open
Decades of research have investigated the mechanical properties of matter under extreme conditions, exploring how materials deform, yield, and fail when subjected to high strain rates. While plasticity codes and computational methods can p…
View article: Radiation and Heat Transport in Divergent Shock-Bubble Interactions
Radiation and Heat Transport in Divergent Shock-Bubble Interactions Open
Shock-bubble interactions (SBI) are important across a wide range of physical systems. In inertial confinement fusion, interactions between laser-driven shocks and micro-voids in both ablators and foam targets generate instabilities that a…
View article: Radiation and heat transport in divergent shock–bubble interactions
Radiation and heat transport in divergent shock–bubble interactions Open
Shock–bubble interactions (SBIs) are important across a wide range of physical systems. In inertial confinement fusion, interactions between laser-driven shocks and micro-voids in both ablators and foam targets generate instabilities that …
View article: X-ray Microscopy and Talbot Imaging with the Matter in Extreme Conditions X-ray Imager at LCLS
X-ray Microscopy and Talbot Imaging with the Matter in Extreme Conditions X-ray Imager at LCLS Open
The last decade has shown the great potential that X-ray Free Electron Lasers (FEL) have to study High Energy Density (HED) physics. Experiments at FELs have made significant breakthroughs in Shock Physics and Dynamic Diffraction, Dense Pl…
View article: Evidence for phonon hardening in laser-excited gold using x-ray diffraction at a hard x-ray free electron laser
Evidence for phonon hardening in laser-excited gold using x-ray diffraction at a hard x-ray free electron laser Open
Studies of laser-heated materials on femtosecond timescales have shown that the interatomic potential can be perturbed at sufficiently high laser intensities. For gold, it has been postulated to undergo a strong stiffening leading to an in…
View article: Characterization of blast waves induced by femtosecond laser irradiation in solid targets
Characterization of blast waves induced by femtosecond laser irradiation in solid targets Open
Blast waves have been produced in solid target by irradiation with short-pulse high-intensity lasers. The mechanism of production relies on energy deposition from the hot electrons produced by laser–matter interaction, producing a steep te…
View article: Behavior of soda-lime silicate glass under laser-driven shock compression up to 315 GPa
Behavior of soda-lime silicate glass under laser-driven shock compression up to 315 GPa Open
Shock experiments give a unique insight into the behavior of matter subjected to extremely high pressures and temperatures. Understanding the behavior of materials under such extreme conditions is key to modeling material failure and defor…
View article: The MEC-U Project at LCLS
The MEC-U Project at LCLS Open
We describe the Matter in Extreme Conditions Upgrade (MEC-U) project, co-locating kilojoule long pulse and high repetition rate petawatt lasers with LCLS in a new experimental hall at SLAC National Accelerator Laboratory.
View article: Novel fabrication tools for dynamic compression targets with engineered voids using photolithography methods
Novel fabrication tools for dynamic compression targets with engineered voids using photolithography methods Open
Mesoscale imperfections, such as pores and voids, can strongly modify the properties and the mechanical response of materials under extreme conditions. Tracking the material response and microstructure evolution during void collapse is cru…
View article: Multi-frame, ultrafast, x-ray microscope for imaging shockwave dynamics
Multi-frame, ultrafast, x-ray microscope for imaging shockwave dynamics Open
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 the…
View article: Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction
Diamond formation kinetics in shock-compressed C─H─O samples recorded by small-angle x-ray scattering and x-ray diffraction Open
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 H…
View article: Novel Fabrication Tools for Dynamic Compression Targets with Engineered Voids Using Photolithography Methods
Novel Fabrication Tools for Dynamic Compression Targets with Engineered Voids Using Photolithography Methods Open
Mesoscale imperfections, such as pores and voids, can strongly modify the properties and the mechanical response of materials under extreme conditions. Tracking the material response and microstructure evolution during void collapse is cru…
View article: Towards performing high-resolution inelastic X-ray scattering measurements at hard X-ray free-electron lasers coupled with energetic laser drivers
Towards performing high-resolution inelastic X-ray scattering measurements at hard X-ray free-electron lasers coupled with energetic laser drivers Open
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 …
View article: Visualization of shocked material instabilities using a fast-framing camera and XFEL four-pulse train
Visualization of shocked material instabilities using a fast-framing camera and XFEL four-pulse train Open
Many questions regarding dynamic materials could be answered by using time-resolved ultra-fast imaging techniques to characterize the physical and chemical behavior of materials in extreme conditions and their evolution on the nanosecond s…
View article: Role of relativistic laser intensity on isochoric heating of metal wire targets
Role of relativistic laser intensity on isochoric heating of metal wire targets Open
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 [ EPL 114 , 45002 ( 2016 ) 10.1209/0295-5075/114/45002 ]. The WDM…
View article: X-ray spectroscopy evidence for plasma shell formation in experiments modeling accretion columns in young stars
X-ray spectroscopy evidence for plasma shell formation in experiments modeling accretion columns in young stars Open
Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation. In particular, we have recently demonstrated the possibility of simulating …
View article: Interaction of relativistically intense laser pulses with long-scale near critical plasmas for optimization of laser based sources of MeV electrons and gamma-rays
Interaction of relativistically intense laser pulses with long-scale near critical plasmas for optimization of laser based sources of MeV electrons and gamma-rays Open
Experiments were performed to study electron acceleration by intense sub-picosecond laser pulses propagating in sub-mm long plasmas of near critical electron density (NCD). Low density foam layers of 300–500 μ m thickness were used as targ…
View article: Interaction of relativistically intense laser pulses with long-scale near critical plasmas for optimization of laser based sources of MeV elec-trons and gamma-rays
Interaction of relativistically intense laser pulses with long-scale near critical plasmas for optimization of laser based sources of MeV elec-trons and gamma-rays Open
Experiments were performed to study electron acceleration by intense sub-picosecond laser pulses propagating in sub-mm long plasmas of near critical electron density (NCD). Low density foam layers of 300-500 um thickness were used as targe…
View article: Enhancement of Quasistationary Shocks and Heating via Temporal Staging in a Magnetized Laser-Plasma Jet
Enhancement of Quasistationary Shocks and Heating via Temporal Staging in a Magnetized Laser-Plasma Jet Open
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 fiel…