Si Foil Research Articles

Thick Architected Silicon Composite Battery Electrodes Using Honeycomb Patterned Carbon Nanotube Forests

To meet the growing performance demands for personal electronics and electric vehicles the energy density of lithium-ion batteries can be increased by incorporating thicker electrodes. We present thick “honeycomb” electrodes based on patterned, vertically aligned carbon nanotubes (CNTs) on Cu foils. Thick electrodes are created by Si deposition on >100 μm tall honeycomb patterned CNTs. Si-CNT electrodes are cycled in half-cells, demonstrating electronic connection between the Si and Cu foil via the aligned CNTs. For ~4.7 mAh cm−2 capacity the honeycomb patterning improves capacity retention (78%) over 30 cycles compared to non-patterned electrodes (58%). We attribute this improvement to the honeycomb’s ability to accommodate Si expansion, thereby reducing cracking that causes active material loss and solid electrolyte interphase instability, and to provide pathways for Li-ion transport into the electrode. The Si-CNT electrode capacity is further increased to 20 mAh cm−2 by increasing the Si loading. Finally, a fluoroethylene carbonate containing electrolyte is used to increase cell lifetime. Here, the honeycomb electrodes have a higher areal (~10.2 mAh cm−2) and retained (65%) capacity over 180 cycles, and exhibit superior rate performance to their non-patterned counterparts. Our work demonstrates the role of patterning in enabling aligned CNTs as a robust template for thick battery electrodes.

Towards 3D Lithium-Ion Full Cells Using Honeycomb-Patterned Carbon Nanotube Forests

The growing demand for electric vehicles and portable electronics has created a significant interest in the scalability, recyclability, and economics of both traditional and emerging battery technologies. Although lithium-ion batteries (LiB) are approaching their theoretical energy density, they will remain a widespread and promising technology as alternative (e.g., Li-metal) chemistries and solid-state architectures are still in relatively early stages of commercial scale-up. Yet, LiB performance can be improved by redesigning the cell geometry to move from planar to 3D designs. 3D designs enable the use of thick electrodes to increase the cell level energy density by minimizing the volume and mass contributions of inactive components, such as current collectors or separators. The rationale for 3D full cell designs lies in the relationship between electrode geometry and the respective energy and power densities. When compared to a planar design, 3D architectures allow for a higher surface area for the same volume and footprint of cell. As a result, a given volume of active material can be distributed with a lower electrode feature thickness. Compared to a planar electrode of a given energy density, the lower thickness contributes to a quadratic improvement in power density which decouples the inherent tradeoff between the energy density and power density that is experienced by planar cells. This suggests that a high aspect ratio 3D cell would give greater power per footprint area while retaining high areal energy density. To meet these criteria, the materials used in fabricating 3D cells must be processable in a manner enabling precise control over geometry, layer conformality and porosity.We are developing thick 3D “honeycomb” full cells by starting with patterned, vertically aligned carbon nanotubes (VA-CNTs) as current collectors. CNTs are widely known to have high thermal and electrical conductivities, and to be mechanically durable; properties which make them an ideal scaffold for 3D cell development. VA-CNTs (“forests”) form by self-organization of CNTs during chemical vapor deposition (CVD) on substrates using common hydrocarbon sources (e.g., C2H2, C2H4). However, well-established CNT growth techniques utilize rigid non-conductive substrates, such as silicon wafers, which necessitates a transfer to a suitable substrate for electrochemical applications. Recently, we translated insights from CNT growth on silicon wafer substrates to grow CNT forests on thin metal foils (Cu) suitable for electrode fabrication. We did this by optimizing the moisture level within the CVD furnace, and using a thin-film stack that forms high-density nanoparticles upon annealing while preventing the poisoning of the Fe catalyst by diffusion of Cu. The resulting CNT forests can reach thicknesses over 350 μm and can be grown from patterned catalyst films having regular hole arrays with feature sizes as small as ~5 μm.Thick composite electrodes are then created by coating CNT forests with Si thin films by CVD. The inherent nanoporosity of the CNT forests (>95%) allows for precursor diffusion into the entirety of the forest cross-section and conformal coating of the individual CNTs. The CVD process is tuned to create dense electrodes with tailored Si loading that can range from ~10 to ~90 at.%. Half-cells using monolithic and honeycomb patterned Si-CNT electrodes (~250 μm tall), Li-metal foil, and a liquid electrolyte/separator combination have been cycled over a range of current densities, demonstrating the electronic connection between the deposited Si and Cu foil via the aligned CNTs. At low current densities and high Si loadings these honeycomb electrodes can exhibit large gravimetric (~1500 mAh/gSi) and areal (~12 mAh/cm2) capacities, with honeycomb Si-CNT composites exhibiting reduced capacity fading when compared to non-patterned electrodes.We continue by investigating these Si-CNT composites as a template for a 3D full cell design. In literature, the difficulty of producing 3D full cells comes from the need to produce high conformality electrolyte films that are pinhole free and which demonstrate sufficient ionic conductivity. To address this issue, we utilize an initiated chemical vapor deposition (iCVD) process to deposit conformal poly(hydroxyethyl methacrylate-co-ethylene glycol diacrylate) thin films on the high aspect ratio CNT forests. These copolymer films are doped with lithium salts to exhibit ionic conductivities on the order of ~10-6 to 10-5 S/cm, which is among the highest conductivities ever exhibited by conformal electrolyte technologies. To complete a full cell design, a slurry-based cathode will be infiltrated into the iCVD coated Si-CNT composite electrodes, from which we aim to assess the cycling behavior and compare the areal energy and power densities of non-patterned and honeycomb architectures.

Electronic interaction of slow hydrogen, helium, nitrogen, and neon ions with silicon

We investigate the electronic excitation of silicon by hydrogen, helium, nitrogen, and neon ions for ion energies ranging from several tens to a few hundred kiloelectronvolts. Experiments are carried out in transmission geometry using a time-of-flight medium energy ion scattering system. The targets are self-supporting, single-crystalline Si (100) foils with nominal thicknesses of 50 and 200 nm. Stopping cross-sections (SCSs) are derived and compared with datasets available from the literature and predictions from theory. The results for H projectiles reveal good agreement with literature datasets, within quoted uncertainties. For He projectiles, the results show good agreement with most of the literature data. For N ions, higher values than reported in the literature are measured. For Ne, where literature data are scarce, we extend the velocity regime for which data exist by a factor of two toward higher velocities. The electronic SCS is found to be proportional to ion velocity for all impinging ions, for velocities below the Bohr velocity $(v<{v}_{0})$. Comparison with theoretical predictions for a homogeneous free electron gas indicates strong contributions of local energy loss processes different from those expected for electron-hole pair excitation in binary collisions for all ions different from protons.

Absolute keV x-ray yield and conversion efficiency in over dense Si sub-petawatt laser plasma

Laser-produced plasmas are bright, short sources of x-rays commonly used for time-resolved imaging and spectroscopy. Their usage implies accurate knowledge of laser-to-x-ray conversion efficiency (CE), spectrum, photon yield and angular distribution. Here, we report on soft x-ray emission in the direction close to the target normal from a thin Si foil irradiated by a sub-PW picosecond laser pulse. These absolute measurements cover a continuous and broad spectral range that extends from 4.75 to 7.3 Å (1.7–2.6 keV). The x-ray spectrum consists of spectral line transitions from highly charged ions and broadband emission with contributions from recombination and free-free processes that occur when electrons decelerate in plasma electromagnetic fields. Angular distribution of the emission was investigated via particle-in-cell simulations, which allowed to estimate the yield into the full solid angle. We find that experimental and simulation estimations of laser to free-free emission CE are in good agreement.

Thick Composite Lithium Ion Battery Electrodes Using Honeycomb-Patterned Carbon Nanotube Forests on Metal Foils

The growing demand for electric vehicles and portable devices has brought significant attention to the scalability, recyclability, and economics of both traditional and emerging battery technologies. Lithium-ion batteries (LIB) are approaching their theoretical energy density yet remain the most widespread and promising technology for the next 5-10 years, as alternative (e.g., Li-metal) chemistries and solid-state architectures are still in relatively early stages of commercial scale-up. An alternative route to improve LIB performance and therefore increase energy density, is to redesign the cell geometry to incorporate thick electrodes. Batteries with thick planar (2D) electrodes suffer from power limitations and capacity loss due to increased Li-ion diffusion distances and tortuosity. 3D electrode designs compensate for this weakness by providing micro-scale channels within the electrode to enable rapid charge transport.Prototype LIBs using 3D electrodes have been fabricated using a wide variety of laboratory techniques (e.g., lithography, imprinting, direct-ink writing), which have afforded study of diverse geometries (e.g., pillar arrays, lattices, interpenetrating structures) and active materials (e.g., Si, Sn, carbon-based, lithium transition metal oxides). However, these methods do not have requisite scalability or compatibility with industrial LIB processing techniques, which demand: (1) integration with cost-effective metal substrates as current collectors; (2) compatibility with commodity anode/cathode materials and electrolytes; and (3) high-rate continuous production and cell assembly. Moreover, the materials used in 3D electrodes must be mechanically robust, electrically conductive, patterned at the microscale level, and have sufficient porosity to accommodate expansion and contraction upon charging and discharging.We are developing thick 3D “honeycomb” battery electrodes using patterned, vertically aligned carbon nanotubes (VA-CNTs) as current collectors. CNTs are widely known to have high thermal and electrical conductivities, and to be mechanically durable. VA-CNTs (“forests”) form by self-organization of CNTs during chemical vapor deposition (CVD) on substrates using common hydrocarbon sources (e.g., C2H2, C2H4). However, well-established CNT growth techniques utilize rigid non-conductive substrates, such as silicon wafers, necessitating an additional transfer step to a suitable substrate. Recently, we translated these insights from CNT growth on silicon wafer substrates to thin metal foils (Cu) suitable for battery electrode fabrication, using optimized in-furnace moisture conditions, and a thin-film interface that forms high-density nanoparticles upon annealing, and prevents diffusion of Cu that is known to poison CNT growth. The resulting CNT forests can reach up to 500 μm thickness and can be patterned to have regular hole arrays with feature sizes as small as ~5 μm.Thick composite electrodes are then created by coating CNT forests with Si thin films by CVD. The inherent nanoporosity of the CNT forests (>95%) allows for precursor diffusion into the entirety of the forest cross-section. The CVD conditions are tuned to create dense electrodes with tailored Si loading ranging from ~10 to ~90 at.%. Half-cells using monolithic and patterned Si-CNT electrodes (~200 μm tall), Li-metal foil and a liquid electrolyte/separator combination are cycled over a range of currents, demonstrating electronic connection between the deposited Si and Cu foil via the aligned CNTs. At low currents (C/5) these electrodes demonstrate large gravimetric capacities, indicating the lithiation of CNTs beneath the deposited Si. We will also investigate cycling performance at high currents (>5C) and perform post-mortem characterization of the Si-CNT interface to study how the CNTs and their patterning govern the stability of the electrode. Future work will look to optimize electrode performance by manipulating the geometric parameters of the CNT forests and assess the economics of CNT-based electrode manufacturing at commercial scales.

Kerfless Si Wafering Using Al Metal Paste, Epoxy and Ni Electroplating as Stress-Induced Layer

Kerfless wafering is a beneficial technique that enhances the cost effectiveness of crystalline silicon (c-Si) solar cells, preventing silicon (Si) waste during diamond sawing. This study compared the advantages of three stress layers for kerfless wafering: aluminum (Al) paste, epoxy-, and electroplated nickel (Ni). These materials demonstrated the ability to exfoliate Si foil, with the electroplated Ni layer having the best result. To control crack propagation, a notch was created by laser scribing on the top and the side of the Si wafer with the Al paste and epoxy layers. The Al paste layer with silicon nitride (SiNx) exfoliated the 1 cm × 1 cm Si foil, and the epoxy layer exfoliated the 5 cm x 5 cm Si foil. However, the Si foils were fragmented after etching of the Al paste and epoxy layers. The thickness of the Si foil increased as the Al paste layer increased. The Al paste layer was etched completely but the epoxy was not removed completely. The Ni layer was electroplated on a titanium/nickel (Ti/Ni) seed layer. A 10 cm × 10 cm Si foil with a thickness of approximately 40 µm was exfoliated using an Ni electroplating method. This Si foil’s effective lifetime increased to 8.17us after Al2O3 passivation and annealing.

Observation of soft X-ray Cherenkov radiation in Be and Si foils

Currently, most of the Cherenkov phenomenon researches for the X-ray region are theoretical studies; there are only a few experiments in this area. Here the new experimental results on observation of X-ray Cherenkov radiation generated by 5.7 MeV electrons in the thin Be and Si foils are presented. The Cherenkov effect from Be was observed for the first time. The experimental results are compared with the calculations performed according to the theoretical model of transition radiation taking into account the oxide layer on the target output surface.

Study the Microstructure of Rapidly Quenched Aluminum 30% Silicon Foils Produced By Using Conventional Method

A simple apparatus based on the hammer and anvil principle has been constructed and used to study the microstructure of aluminum 30% Silicon (Al-30% Si) foils with different thicknesses. Both (hammer and anvil) have been fabricated from oxygen free of high conductivity (OFHC) red copper. The cooling rate achieved or estimated was to be in the range of 1.67x104: 5x104 k sec-1. Microstructure studying of rapidly quenched Al-30% Si foils indicated that with decreasing the foil thickness the size of primarily Si crystalline decreases in the whole investigated range. However the volume fraction of the primarily silicon crystals in the structure remained constant down to thickness 0.3 mm; with further decreasing of the thickness the primarily silicon volume started to decreases.

Effect of plastic coating on the density of plasma formed in Si foil targets irradiated by ultra-high-contrast relativistic laser pulses.

The formation of high energy density matter occurs in inertial confinement fusion, astrophysical, and geophysical systems. In this context, it is important to couple as much energy as possible into a target while maintaining high density. A recent experimental campaign, using buried layer (or "sandwich" type) targets and the ultrahigh laser contrast Vulcan petawatt laser facility, resulted in 500 Mbar pressures in solid density plasmas (which corresponds to about 4.6×10^{7}J/cm^{3} energy density). The densities and temperatures of the generated plasma were measured based on the analysis of x-ray spectral line profiles and relative intensities.

Interaction Between Si and N in Solidified Austenitic Fe in 1373–1473 K

In order to investigate the thermodynamic interactions between Si and N in austenitic Fe, equilibrium experiments of Fe–Si foils and N2 gas with controlled partial pressure were carried out at 1373, 1423 and 1473 K. Based on the equilibrium concentration of N in the Fe foil with different Si content, the first order interaction coefficient between Si and N in austenitic Fe could be determined in 1373–1473 K and its temperature dependency was found to be as follows. In the austenitic Fe, Si and N have a positive interaction coefficient value, which has a repulsive relationship with each other. Using interaction between Si and N, the precipitation behavior of various nitrides is to be predicted.$$e_{{\text{N}}}^{{{\text{Si}}}} = \frac{199.5}{{\text{T}}} - 0.119$$

Nanocrystalline Li-Al-Mn-Si Foil as Reversible Li Host: Electronic Percolation and Electrochemical Cycling Stability.

When a metallic foil (Li metal or LixAl) with initial Li inventory (LiInv) is used as the anode in lithium-ion batteries, its metallurgical damage state in the presence of organic liquid electrolyte and cycling electrochemical potential is of great interest. While LixAl foil operates at a voltage that eliminates LiBCC dendrite, the state-of-health (SOH) of LixAl anode can still degrade quickly in full-cell cycling. To analyze the causes, we decompose SOH = SOHe × SOHi × LiInv, where SOHe is SOH of electronic percolation within the anode, SOHi is SOH of Li percolation from cathode to the anode interior, and LiInv is the amount of cyclable lithium in a full cell, all normalized such that 1 means perfectly healthy, and 0 means dead. Any of the three (SOHe, SOHi, LiInv) dropping to zero would mean death of the full cell. Considering the poor performance of pure Al foil due to rapid drop in LiInv, we employed a mechanical prelithiation (MP) method to make LiInv >1 initially. The chemomechanical shock from MP creates an ultrananocrystalline LiAl layer with grain size 10-30 nm on top of unreacted Al. We then monitor SOHe evolution of the anode foil by measuring the in-plane electronic conductance in situ. We find that small additions of Mn or Si into Al induce nanoprecipitates Zener pinning, and the resulting denser grain boundary (GB) network before MP significantly reduces foil porosity after MP, delays gross foil fracture, and improves SOHe in subsequent cycling. Microstructural analysis reveals that the refined grain size of foil before MP relieves stress and reduces the chance of forming electronically isolated dead grain cluster due to cracking and invasion of electrolyte and solid-electrolyte interphase (SEI). By maintaining good electronic percolation, binder-free LixAlMnSi anode demonstrates an order-of-magnitude more stable SOHe and better electrochemical cycling performance than LixAl anode.

Production and characterization of thin, self-supporting Si foils for use as targets in radioactive beam experiments

Development of thin, self-supporting silicon foils (both natural and isotopically-enriched) for use as targets in reaction studies with radioactive beams is detailed. Foils with a thickness of ∼220μg/cm2 were produced using vapor deposition and were floated onto aluminum frames with 10–15 mm diameter holes. During their production, the foil thickness was measured using a quartz crystal monitor. Subsequently, the foil thickness was characterized by α particle energy loss measurements and Rutherford backscattering (RBS). These measurements demonstrated that the thickness could be determined to within a 0.5% uncertainty. The elemental purity of the foils was assessed using RBS and X-ray photoelectron spectroscopy. This analysis demonstrated that the foils have 87%–90% silicon abundance.

Freestanding and supported processing of sub-70 μm kerfless epitaxial Si and thinned Cz/FZ Si foils into solar cells: An overview of recent progress and challenges

Utilisation of expensive silicon (Si) material in crystalline Si modules has come down to 4 g Si per watt-peak in 2018, mainly as a result of reduction in wafer thickness and kerf losses as well as increase in module efficiencies. With continued progress in conventional multi-wire sawing of ingots, wafers as thin as 100 μm could eventually be produced. Beyond this, kerfless lift-off technologies are being investigated which enable wafer thicknesses well below 100 μm with negligible Si kerf waste. Such thin Si wafers and foils would be much lighter in weight than today's standard 165-180 μm-thick wafers and would exhibit considerable flexibility and fragility. This necessitates a rethink about how to handle and process thin Si into solar devices in a manufacturing line with high mechanical yield and high throughput. This paper gives a broad overview of the different approaches for fabricating solar cells on thin Si foils. In particular, three routes are discussed in detail, namely (1) freestanding processing of thin Si, (2) processing of thin Si supported mechanically on a conductive low-cost Si substrate (“wafer-equivalent” approach) and (3) processing of thin Si bonded to a transparent glass superstrate. In each case, the main challenges are explained and the recent progress in addressing them are summarised. Kerfless 50 μm-thick epitaxial Si foils lifted-off using porous Si and thinned-down Si wafers (below 70 μm) are used as model substrates for this work.

Study of laser produced plasma in a longitudinal magnetic field

Laser produced plasma embedded in a longitudinal magnetic field was studied using a 1 MA pulsed power generator coupled with a 50 TW laser. Half turn coil loads with an internal diameter of 2.5–3.5 mm generate a 50–70 T axial magnetic field near the load. A subpicosecond laser pulse with an intensity of 1018–1019 W/cm2 irradiates a thin Si foil target in the magnetic field of the coil load. A laser produced plasma plume collimates within the longitudinal field to a narrow jet 0.2–0.3 mm in diameter with a length of 3–4 mm and an electron plasma density of (0.2–1) × 1020 cm−3 on the jet axis. The jet propagates with a velocity of 160–200 km/s in general agreement with magnetohydrodynamic simulations. X-ray spectral measurements show an increase in the plasma electron density resulting from the magnetic confinement of the jet.

(111)Si thin layers detachment by stress-induced spallation

In this work, results of controlled detachment of (111) silicon by stress induced spalling (SIS) process, which is based on a gluing on a metallic stressor layer by an epoxy adhesive on top of a silicon substrate, are presented. It is shown that silicon foils mainly (1 × 1) cm2 with different thicknesses (~50–170 µm) can be successfully detached using different materials (steel, copper, aluminum, nickel and titanium) as stressor layers with thicknesses ~50–500 µm. Such detachment can be realized by dipping of a stressor/glue/silicon wafer based structure into liquid nitrogen. As a result, Si foils with different thicknesses from ~50 µm to ~170 µm can be detached. An analytical and numerical approaches based on principles of linear elastic fracture mechanics is developed and they are shown that such approaches can predict general trends and conditions for the detachment of silicon foils with desired thicknesses using a stressor layer. Raman spectroscopy analysis of the residual stresses in detached silicon foils shows, that tensile stresses (up to −36 MPa) as well as higher value compressive stresses (up to ~444 MPa) are present in such foils. Moreover, optical and scanning electron microscopy (SEM) measurements show that surface of the detached foils exhibits some periodic lines originated by stresses.

SiC foam sandwich structures obtained by Mo-wrap joining

SiC foams sandwiched between two Ceramic Matrix Composite (CMC) skins are of interest for several high temperature applications ranging from aeronautics to energy production.In this paper, SiC foams were joined to C/SiC composites by the “Mo-wrap” method to obtain sandwich structures. The Mo-wrap method is a recently developed joining technique: it consists of wrapping Si foils inside a Mo wrap in order to prevent molten silicon leaking from the joined area and infiltrating SiC foam and C/SiC during the joining process.Compression and thermal shock resistance tests were performed on the C/SiC – SiC foam – C/SiC sandwich obtaining sound results.

Heterojunction IBC Solar Cells on Thin (< 50μm) Epitaxial Si Foils Produced from Kerfless Layer Transfer Process

Heterojunction IBC Solar Cells on Thin (< 50μm) Epitaxial Si Foils Produced from Kerfless Layer Transfer Process

Highly accurate nuclear and electronic stopping cross sections derived using Monte Carlo simulations to reproduce measured range data

We have examined and confirmed the previously unexplored concept of using Monte Carlo calculations in combination with measured projected ranges of ions implanted in solids to derive a quantitative description of nuclear interaction and electronic stopping. The study involved 98 ranges of 11B in Si between 1 keV and 8 MeV, contained in 12 sets of 10 different groups. Systematic errors by up to ±8% were removed to establish a refined data base with 93 ranges featuring only statistical uncertainties (±1.8%). The Monte Carlo calculations could be set up to reproduce the refined ranges with a mean ratio 1.002 ± 1.7%. The input parameters required for this very high level of agreement are as follows. Nuclear interaction is best described by the Kr-C potential, but in obligatory combination with the Lindhard-Scharff (LS) screening length. Up to 300 keV, the electronic stopping cross section is proportional to the projectile velocity, Se = kSe,LS, with k = 1.46 ± 0.01. At higher energies, Se falls progressively short of kSe,LS. Around the Bragg peak, i.e., between 0.8 and 10 MeV, Se is modeled by an adjustable function serving to tailor the peak shape properly. Calculated and measured isotope effects for ranges of 10B and 11B in Si agree within the experimental uncertainty (±0.25%). The range-based Se,R(E) reported here predicts the scarce experimental data derived from the energy loss in projectile transmission through thin Si foils to within 2% or better. By contrast, Se(E) data of available stopping power tables exhibit deviations from Se,R(E) between −40% and +14%.

X-ray spectroscopy of super-intense laser-produced plasmas for the study of nonlinear processes. Comparison with PIC simulations

We present X-ray spectroscopic diagnostics in femto-second laser-driven experiments revealing nonlinear phenomena caused by the strong coupling of the laser radiation with the created plasma. Among those nonlinear phenomena, we found the signatures of the Two Plasmon Decay (TPD) instability in a laser-driven CO2 cluster-based plasma by analyzing the Langmuir dips in the profile of the O VIII Lyε line, caused by the Langmuir waves created at the high laser intensity 3 1018Wcm-2. With similar laser intensities, we reveal also the nonlinear phenomenon of the Second Harmonic Generation (SHG) of the laser frequency by analyzing the nonlinear phenomenon of satellites of Lyman δ and ε lines of Ar XVII. In the case of relativistic laser-plasma interaction we discovered the Parametric Decay Instability (PDI)-induced ion acoustic turbulence produced simultaneously with Langmuir waves via irradiation of thin Si foils by laser intensities of 1021Wcm-2.

Using X-ray spectroscopy of relativistic laser plasma interaction to reveal parametric decay instabilities: a modeling tool for astrophysics.

By analyzing profiles of experimental x-ray spectral lines of Si XIV and Al XIII, we found that both Langmuir and ion acoustic waves developed in plasmas produced via irradiation of thin Si foils by relativistic laser pulses (intensities ~1021 W/cm2). We prove that these waves are due to the parametric decay instability (PDI). This is the first time that the PDI-induced ion acoustic turbulence was discovered by the x-ray spectroscopy in laser-produced plasmas. These conclusions are also supported by PIC simulations. Our results can be used for laboratory modeling of physical processes in astrophysical objects and a better understanding of intense laser-plasma interactions.