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Silicon polymorphs with exotic electronic and optical properties have recently attracted significant attention due to the wide range of useful bandgap characteristics1,2,3,4. They are typically formed by high pressure techniques, which put limitations on the sample volumes and their crystal structure5,6,7,8,9,10. This constitutes a major obstacle to study these polymorphs and their incorporation into existing technology. Here, we report on a new approach to create unusual crystal structures deep into the bulk of a silicon wafer by MeV-electrons generated by laser irradiation at ultra-relativistic intensity above ~2x10^18 W/cm2. Strong repulsion between the electrons, their branching due to self-generated magnetic field and nonlinear relativistic effects11,12,13 enhance deposition of their energy deep into the target and form high energy density conditions leading to ionisation, followed by fast quenching and restructuring into new crystal arrangements14,15,16,17,18. Analysis by Raman spectroscopy, synchrotron X-ray diffraction, and high-resolution transmission electron microscopy of nanocrystals formed in the irradiated samples provide compelling evidence of the formation of metastable Si phases. The unexplored domain of material transformations exposed to laser-produced MeV-electrons opens new pathways for the conversion into new crystal structures applicable to a wide range of materials at considerably larger quantity, all preserved for further studies and exploitation.

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 2 O systems, respectively. Here, we investigate a stoichiometric mixture of C and H 2 O 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 H 2 O 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.

The full-energy beam injection system from SACLA to the SPring-8 storage ring has been developed. Low-emittance beam injection is required for the future upgrade of SPring-8 due to its small injection beam aperture. The electron beam injection from an X-ray free-electron laser linear accelerator not only satisfies the emittance requirement but also it confers a cost benefit compared to a conventional dedicated injector system. In SPring-8, the SACLA linear accelerator is now delivering X-ray free-electron laser photon beams and serving as a full-time injector of SPring-8 in parallel.

A new method of spatially resolved single-shot absorption spectroscopy for an x-ray free electron laser (XFEL) pulse has been developed by using a dispersive spectrometer and an elliptical mirror to enhance the spatial resolution. As a demonstration, we performed x-ray absorption near-edge structure measurement of Cu with a pump–probe scheme combining an XFEL pulse and a high-power femtosecond laser pulse. In the experiment, changes of an absorption spectrum in a plasma generated with a laser shot were successfully observed. The method will be a powerful tool for experiments requiring a spatial resolution and/or a single-shot measurement, such as high energy density science using a high-power laser pulse.

An experimental platform using X-ray free-electron laser (XFEL) pulses with high-intensity optical laser pulses is open for early users' experiments at the SACLA XFEL facility after completion of the commissioning. The combination of the hard XFEL and the high-intensity laser provides capabilities to open new frontiers of laser-based high-energy-density science. During the commissioning phase, characterization of the XFEL and the laser at the platform has been carried out for the combinative utilization as well as the development of instruments and basic diagnostics for user experiments. An overview of the commissioning and the current capabilities of the experimental platform is presented.

We constructed a synchronized femtosecond optical laser system with spatiotemporal stabilization for pump-probe experiments at SPring-8 Angstrom Compact Free Electron Laser (SACLA). Stabilization of output power and pointing has been achieved with a small fluctuation level of a few percent by controlling conditions of temperature and air-flow in the optical paths. A feedback system using a balanced optical-microwave phase detector (BOMPD) has been successfully realized to reduce jitter down to 50 fs. We demonstrated the temporal stability with a time-resolved X-ray diffraction measurement and observed the coherent phonon oscillation of the photo-excited Bi without the post-processing using the timing monitor.

The extreme pressures achievable with dynamic compression holds great promise for studying planetary interiors. Phase stability of Fe-Si alloys, which are complex to address, is particularly relevant to understanding telluric planetary cores due to the widely varying properties produced by small changes in Si concentration. Here we report the study of phase stability of pure iron and Fe-Si alloys by x-ray diffraction measurements carried out on shocked samples using an x-ray free electron laser (XFEL). Our setup combined with the brilliance of the XFEL allows us to observe the rapid onset of high-pressure solid-solid phase transformation in Fe and Fe-Si8.5wt%; we observe no such evidence in Fe-Si16wt% up to 110 GPa on the nanosecond timescale. Density Functional Theory calculations provide the conceptual framework to rationalize these observations. Taken together our experiments and calculations support recent dynamic compression measurements and shed light on conflicting static compression results. Our work highlights the need to properly consider the differing intrinsic timescales of the static and dynamic experiments when comparing results, and the complementarity of the techniques in assessing phase diagram and transition mechanisms.

Meteorites from interplanetary space often include high-pressure polymorphs of their constituent minerals, which provide records of past hypervelocity collisions. These collisions were expected to occur between kilometre-sized asteroids, generating transient high-pressure states lasting for several seconds to facilitate mineral transformations across the relevant phase boundaries. However, their mechanisms in such a short timescale were never experimentally evaluated and remained speculative. Here, we show a nanosecond transformation mechanism yielding ringwoodite, which is the most typical high-pressure mineral in meteorites. An olivine crystal was shock-compressed by a focused high-power laser pulse, and the transformation was time-resolved by femtosecond diffractometry using an X-ray free electron laser. Our results show the formation of ringwoodite through a faster, diffusionless process, suggesting that ringwoodite can form from collisions between much smaller bodies, such as metre to submetre-sized asteroids, at common relative velocities. Even nominally unshocked meteorites could therefore contain signatures of high-pressure states from past collisions., Meteorites from space often include denser polymorphs of their minerals, providing records of past hypervelocity collisions. An olivine mineral crystal was shock-compressed by a high-power laser, and its transformation into denser ringwoodite was time-resolved using an X-ray free electron laser.

We present the study of optical and spectral properties of radiation-induced stable point defects, known as color centers (CCs), in lithium fluoride (LiF) for the detection of 10 keV XFEL beam at Spring-8 Angstrom Compact free electron LAser (SACLA) in Japan. A thick LiF crystal was irradiated in four spots with 10 keV XFEL beam (pulse duration = 10 fs) with different number of accumulated shots. After irradiation the colored-LiF spots were characterized with an optical microscope in fluorescence mode and their photoluminescence intensity and spectra were analyzed.

Fast-ignition laser fusion involves directing an intense relativistic electron beam onto a fuel target. Experiments and simulations now enable a visualization of the location of fast electrons and the energy-coupling mechanisms at play.

Thermal reactions of materials heated by charged particles may lead to serious damage in a laser fusion reactor. When charged particles irradiate and heat the wall material with high intensity like at above 10 9 W/cm 2 , the material can be ablated. Once the wall is ablated, expanding gas or plasma can disturb the propagation of laser light irradiating the fuel target if it stagnates long enough for next laser shot. In order to understand the ablation dynamics in detail, we have performed 1-D hydro simulation to evaluate this ablation. As a new feature, we introduce the calculation of energy deposition by charged particles focusing on the interaction between ablated material and charged particles.

The dynamic fracture of tantalum is observed at the atomic scale using an x-ray monitoring technique at the SACLA XFEL facility., The understanding of fracture phenomena of a material at extremely high strain rates is a key issue for a wide variety of scientific research ranging from applied science and technological developments to fundamental science such as laser-matter interaction and geology. Despite its interest, its study relies on a fine multiscale description, in between the atomic scale and macroscopic processes, so far only achievable by large-scale atomic simulations. Direct ultrafast real-time monitoring of dynamic fracture (spallation) at the atomic lattice scale with picosecond time resolution was beyond the reach of experimental techniques. We show that the coupling between a high-power optical laser pump pulse and a femtosecond x-ray probe pulse generated by an x-ray free electron laser allows detection of the lattice dynamics in a tantalum foil at an ultrahigh strain rate of ε. ~2 × 108 to 3.5 × 108 s−1. A maximal density drop of 8 to 10%, associated with the onset of spallation at a spall strength of ~17 GPa, was directly measured using x-ray diffraction. The experimental results of density evolution agree well with large-scale atomistic simulations of shock wave propagation and fracture of the sample. Our experimental technique opens a new pathway to the investigation of ultrahigh strain-rate phenomena in materials at the atomic scale, including high-speed crack dynamics and stress-induced solid-solid phase transitions.

This article reports the progress in the beamlines at the SPring-8 Angstrom Compact free electron LAser (SACLA). The beamline optical and diagnostics systems have been upgraded to further accelerate the scientific applications of X-ray free-electron lasers (XFELs). End-station instruments have also been developed to provide user-friendly experimental platforms which allow efficient data collection. Along with the upgrades of beamlines and experimental stations, we have established reliable and efficient procedures of the beamline operation.

It is of critical importance in many physics fields to compare results both from simulation and experiments. In order to make this comparison efficient, visualization of experimental and simulation data is rather essential. In this paper, we focus on the colliding plasma plumes using laser produced plasmas to understand the basic physics in a nuclear laser fusion reactor. To visually compare dynamical data acquired through experiments and simulations, we propose a visualization method to highlight overlapping space-time regions of XYT-space volumes. The visualization of the XYT-space volumes is conducted based on particle-based techniques. First, input data for an experiment and a simulation are both converted into the XYT-space volumes and then further converted into particle data. Second, we perform the particle-based volume fusion. Third, we conduct the particle-based evaluation of the degrees of overlapping and highlight highly overlapping regions using colors with large whiteness. We demonstrate the effectiveness of our method by applying it to the plasma plume collision of tungsten. Our method has visually proven that the univalent ionized plasma is the most dominant plasma in the experiment.

Introduction: The purpose of this study was to quantify the histomorphometric properties of alveolar bone to identify the characteristics of the changes of quantity and quality of alveolar bone between the maxilla and the mandible during orthodontic tooth movement in dogs. Methods: A force of 200 to 250 g was applied from miniature implants to the premolars for either 4 or 12 weeks. Maxillary and mandibular tooth specimens were embedded and sectioned at 100 μm in the sagittal plane for microscopic examination. Results: Significantly more orthodontic tooth movement was observed for maxillary than for mandibular teeth. The primary histomorphometric analysis indicated that, after 4 weeks of tooth movement, a marginal increase in resorptive parameters was associated with a decrease of bone volume at both the tension and compression sites. On the other hand, after 12 weeks of tooth movement, secondary histomorphometric analysis indicated an increase in the bone formation rate, resulting in increased woven bone formation, especially at the tension sites. Conclusions: Clinically, maxillary and mandibular bone responds differently to orthodontic force, resulting in a significant difference in the amounts of tooth movement. Significant differences in the primary and secondary histomorphometric indexes between the jaws and at the different time points during orthodontic tooth movement might affect the amount and rate of tooth movement in orthodontic patients. Moreover, orthodontic tooth movement is characterized by a regional acceleratory phenomenon, manifested as increased bone turnover in the alveolar process.

Several plasma devices to control energetic electrons produced by ultra-intense lasers are studied. Cone targets guide the lasers and electrons, and enhance the generation of energetic electrons consequently. Plasma fibers confine and guide the energetic electrons, and lead an electron beam with very small spatial spread. Plasma lenses transport and collimate the energetic electrons into a very tiny spot. Grating plasmas give out Smith-Purcell radiations. The energy concentration brought by these energetic electrons in the methods of plasma photonics is improved more than 3 magnitudes compared to the simple plane targets, and new radiation source with tunable wavelength induced by energetic electrons is available.

We use one- and two-dimensional particle-in-cell simulations to demonstrate that the propagation of an ultraintense laser (I=10(19)W/cm(2)) in critical density plasma can be interfered with by a high density plasma wall region generated at the propagation front. When the electron flow speed of the wall region exceeds a certain relativistic threshold, the region behaves as an overdense plasma due to a decrease of the effective critical density. The region forms then very small overdense plasma islands. The islands impede the propagation intermittently and slow down the propagation speed significantly.

We experimentally studied relativistic laser propagation in preplasmas at the highest powers ever attempted-0.2 to 0.4petawatt. We demonstrated a single conical-shaped plasma channel formation extending several hundred microns in length from the under dense to over dense plasmas, indicating whole-beam self-focused laser channeling into the high-density plasma. The channel cone was reproduced by a three dimensional particle-in-cell simulation. The confirmation of the relativistic laser channeling into high-density plasmas holds the promise of fast igniting a highly compressed fuel plasma core.

Immunohistochemistry for brain-derived neurotrophic factor (BDNF) was performed on the rat trigeminal ganglion (TG). The immunoreactivity (IR) was detected in 46% of TG neurons. These neurons were mostly small- or medium-sized (range, 149.7-1246.3 microm2; mean +/- SD = 373.4 +/- 151.6 microm2). A double immunofluorescence method also revealed that 54% of BDNF-immunoreactive (IR) neurons were immunoreactive for calcitonin-gene-related peptide. In addition, 93% of BDNF-IR TG neurons contained vanilloid receptor subtype 1. However, the co-expression of BDNF and vanilloid receptor 1-like receptor was very rare (less than 1%). In the trigeminal sensory nuclei, laminae II of the medullary dorsal horn was abundant in presumed BDNF-IR axon terminals. Such profiles were also detected in the dorsolateral part of the subnucleus oralis. The retrograde tracing and immunohistochemical methods demonstrated that BDNF-IR was common among cutaneous TG neurons (47%) but not tooth pulp TG neurons (13%). The present study indicates that BDNF-IR TG neurons have unmyelinated axons and project to the superficial medullary dorsal horn. It is likely that BDNF-containing neurons in both the trigeminal and spinal sensory systems have similarities in morphology and function. However, the content of BDNF in TG neurons probably depends on their peripheral targets. BDNF seems to convey nociceptive cutaneous input to the trigeminal sensory nuclei.

It is suggested that bulk acceleration of ions can occur in a target with density discontinuities when hot electrons are transported through the target. A foam target just belongs to such a kind of target, which is composed of irregular lamellar layers distributed randomly. To simplify the problem, we study the interaction of a high intensity laser pulse with a target consisting of regular micro-thin layers separated with a thickness of around a micrometre. Particle-in-cell simulations suggest that localized electrostatic fields with multi-peaks around the surfaces of the thin layers inside are induced when fast electrons produced are transported through such a target. These fields inhibit hot electron transport and simultaneously accelerate ions from the thin layers inside the target, forming a bulk acceleration in contrast to the surface acceleration at the front and rear sides of a thin solid target. Bulk acceleration can produce a large number of ions of moderate energy, which may be useful for applications such as fast ignition by fast protons. Experimental evidence of bulk acceleration is found with low-density foams irradiated by ultra-intense laser pulses.

Fast electron transport and spatial energy deposition are investigated in integrated cone-guided Fast Ignition experiments by measuring fast electron induced copper K-shell emission using a copper tracer added to deuterated plastic shells with a geometrically reentrant gold cone. Experiments were carried out at the Laboratory for Laser Energetics on the OMEGA/OMEGA-EP Laser where the plastic shells were imploded using 54 of the 60 OMEGA60 beams (3ω, 20 kJ), while the high intensity OMEGA-EP (BL2) beam (1 ω, 10 ps, 500 J, Ipeak > 1019 W/cm2) was focused onto the inner cone tip. A retrograde analysis using the hybrid-PIC electron transport code, ZUMA, is performed to examine the sensitivity of the copper Kα spatial profile on the laser-produced fast electrons, facilitating the optimization of new target point designs and laser configurations to improve the compressed core areal density by a factor of 4 and the fast electron energy coupling by a factor of 3.5.

It is demonstrated experimentally and by numerical simulations that the presence of a long-pulse-laser-created back plasma on the target backside can focus the relativistic electrons produced by short-pulse laser interaction with the front of a solid target. Comparing this to that without the back plasma, the number density of the fast electrons is increased by one order of magnitude, and their divergence angle is reduced fivefold. The effect is attributed to the absence of the backside sheath electric field and the collimation effect of the megagauss self-generated baroclinic magnetic field there. Such an acceleration scheme can be useful to applications requiring high-energy and charge-density electron bunches, such as fast ignition in inertial fusion.

Refluxing of fast electrons generated by high-intensity, short-pulse lasers was investigated by measuring electron-induced Kα x rays from a buried tracer layer. Using planar foils of Au/Cu/CH, the 150-J, 0.7-ps TITAN short-pulse laser was focused on the gold foil to generate fast electrons and the 3-ns, 300-J long pulse beam irradiated on the CH side to create expanding plasma as a conducting medium. By delaying the short-pulse beam timing from the long pulse laser irradiation, the plasma size was varied to change electron refluxing in the target rear. The total yields and two-dimensional images of 8.05-keV Cu-Kα x ray were recorded with an x-ray spectrometer and two monochromatic crystal imagers. The measurements show that the integrated yields decrease by a factor of 10 from refluxing to the nonrefluxing limit. Similar radial profiles of the Kα images in the rear were observed at all delays. Hybrid-particle-in-cell simulations using plasma profiles calculated by a radiation-hydrodynamic code HYDRA agree well with the measured Kα yields. The simulations suggest that conducting plasma with the size of ∼300 μm in the laser direction and ∼600 μm in the lateral direction at the density of 2 × 1020 1/cm3 is sufficiently large to prevent electrons from refluxing in the target. The parameters found in this study can be useful in designing experiments utilizing a Kα x-ray source in refluxing regime or a tracer layer in nonrefluxing regime.

High intensity laser propagation in plasmas is one of the key issues in fast ignition scheme of laser fusion energy. We have investigated experimentally and computationally the laser propagation in dense plasmas. The experiment demonstrates plasma channel formation and indicates laser propagation through overdense plamsas with relativistic self-focusing. The channel direction coincides with the laser axis. Two and three-dimensional particle-in-cell simulation reproduces the plasma channel and reveals that the laser propagation is dependent on the laser focus position in plasmas.

We have studied energy distribution of fast electrons passing through a highly compressed core plasma for fast ignition research in inertial confinement fusion. Recent PIC calculations indicate that the collective effect of electric and magnetic fields on the transport may be less significant than the binary collisions in the case of a high density fusion pellet. In order to understand the net effect of binary collisions in dense plasma, we calculate electron energy distributions at several viewing angles using an electromagnetic cascade Monte-Carlo simulation, EGS5, for estimation of the contribution of multi collisional process. Here, the construction of physical parameters in the code were taken from the calculation results given by 2 dimensional particle-in-cell simulations. In the result, the number of electrons detected on the laser axis within the range to 15 MeV significantly decreases for the superdense region (max: 1.6 · 10 25 (/cm 3 )) compared with the low density plasma. The reduction on the electron number decreases with increase of observation angles gradually and finally the number almost coincides more than 40 degrees.

Summary form only given. With the recent 192-beam experiments at the National Ignition Facility, attention has been directed towards the next step to build a DEMO reactor with a reasonably high-repetition rate (~10Hz) of implosion. Along with repeated implosion, however, the interior of target chamber is exposed to intense pulses of DT-fusion neutrons, X-rays, unburned fuel particles, He-ash and pellet debris. As a result, wall materials will be subject to ablation, emitting particles in the plasma state. Ablated particles will either be re-deposited elsewhere on the wall or collide with each other in the center-of-symmetry region, if any, of the target chamber. Colliding ablation plasma particles may lead to the formation of clusters which can grow into aerosol, possibly floating thereafter. This would affect the subsequent implosion. It is also predictable that tritium be incorporated into re-deposited materials. Despite their importance, the chamber clearing and tritium codeposition issues have not yet been addressed in the inertial fusion community. To investigate the behavior of colliding ablation plasma plumes, a series of systematic experiments have been carried out over the past several years [1, 2, 3]. Used for these experiments is a well-diagnosed laboratory setup in which two arc-shaped targets are set in such a way that ablation plasma plumes, generated simultaneously by 10Hz, 6ns, YAG laser beams, collide with each other in the center-of-arc region. The laser power density ranges from 1 to 30 J/cm2/pulse and the repetition rate is set at 10Hz. These laser ablation experiments have been done both in high vacuum, in hydrogenic atmosphere, and additionally in the present work, in glow discharge plasmas of inert gases. Employed as the target materials are: Li, C, W and Pb, all candidate materials for ICF reactor applications. Data indicate that metallic targets tend to form aerosol in the form of droplet, the diameter of which is of the orders of 100nano~1micron meters, whereas colliding carbon plumes form carbon nano/micro-tubes and fullerene onions, etc. Contrary to our prediction, hydrogen co-deposition has been found to be more significant with carbon than with lithium, the latter of which forms a hydride, though. Possible mechanisms are proposed to understand the aerosol formation and hydrogen co-deposition behavior and effects of background inert gas plasma on them.

Emission of energetic protons (maximum energy \ensuremath{\sim}18 MeV) from the interaction of relativistic intensity laser with a cone-wire target is experimentally measured and numerically simulated with hybrid particle-in-cell code, lsp [D. R. Welch et al., Phys. Plasmas 13, 063105 (2006)]. The protons originate from the wire attached to the cone after the OMEGA EP laser (670 J, 10 ps, 5 \ifmmode\times\else\texttimes\fi{} 10${}^{18}$ W/cm${}^{2}$) deposits its energy inside the cone. These protons are accelerated from the contaminant layer on the wire surface, and are measured in the radial direction, i.e., in a direction transverse to the wire length. Simulations show that the radial electric field, responsible for the proton acceleration, is excited by three factors, viz., (i) transverse momentum of the relativistic fast electrons beam entering into the wire, (ii) scattering of electrons inside the wire, and (iii) refluxing of escaped electrons by ``fountain effect'' at the end of the wire. The underlying physics of radial electric field and acceleration of protons is discussed.

Recently, the use of miniscrews as an anchorage device has become a routine approach in the orthodontic field. However, there is no report that has analyzed the healing process of the miniscrew, such as the thickness of the cortical bone, in the past.In the present study, to histologically assess the healing process of the osseous tissue surrounding miniscrews used as an orthodontic anchorage, the change in the thickness of the cortical bone was analyzed after 3, 6, and 12 weeks after the placement. Furthermore, the change in the bone-implant contact in different regions of the miniscrew during the initial healing period was also investigated.Ninety-six miniscrews were placed in eight beagle dogs. After 3, 6, and 12 weeks of healing, a force of 200-300 g was applied to the force-applied groups for 12 weeks. Non-forced groups remained in the jaw without force application.In the non-forced groups, a significant amount of cortical bone was formed at the head of the miniscrew at the initial stage of the healing process in the maxilla. However, less cortical bone formation was observed in the mandible. After the force application, increased bone formation was observed within 1 mm of the miniscrew compared to other regions in both jaws. In the mandible, significantly less cortical bone was observed 3 and 6 weeks after the force application. Bone-implant contact revealed that the osseous tissue surrounding the miniscrew matured from the apex toward the head of the miniscrew.We suggest that this sufficient amount of cortical bone at the initial stage of healing enables the immediate loading in miniscrews to resist against orthodontic force. Furthermore, less amount of cortical bone formed at the head of the miniscrew may be one reason for the higher failure rate in the mandible.

Since an imaging plate (IP) is sensitive to electron, ion, and x rays, it can be used as a detector for laser plasma experiment using ultraintense laser. Moreover, an IP has the advantageous features such as high sensitivity, wide dynamic range, and high spatial resolution. Even though IP itself has a considerable wide dynamic range up to 10(5), the IP data have appeared often saturated at an IP reading device. We propose a reading technique by inserting optical density filters so that an apparently saturated IP data can be saved.

We produced cylindrically imploded plasmas, which have the same density-radius product of the imploded plasma rhoR with the compressed core in the fast ignition experiment and demonstrated efficient fast heating of cylindrically imploded plasmas with an ultraintense laser light. The coupling efficiency from the laser to the imploded column was 14%-21%, implying strong collimation of energetic electrons over a distance of 300 microm of the plasma. Particle-in-cell simulation shows confinement of the energetic electrons by self-generated magnetic and electrostatic fields excited along the imploded plasmas, and the efficient fast heating in the compressed region.

${K}_{\ensuremath{\alpha}}$ x-ray emission, extreme ultraviolet emission, and plasma imaging techniques have been used to diagnose energy transport patterns in copper foils ranging in thickness from 5 to $75\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ for intensities up to $5\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{W}\text{ }{\mathrm{cm}}^{\ensuremath{-}2}$. The ${K}_{\ensuremath{\alpha}}$ emission and shadowgrams both indicate a larger divergence angle than that reported in the literature at lower intensities [R. Stephens et al., Phys. Rev. E 69, 066414 (2004)]. Foils $5\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ thick show triple-humped plasma expansion patterns at the back and front surfaces. Hybrid code modeling shows that this can be attributed to an increase in the mean energy of the fast electrons emitted at large radii, which only have sufficient energy to form a plasma in such thin targets.

We propose a foam cone-in-shell target design aiming at optimum hot electron production for the fast ignition. A thin low-density foam is proposed to cover the inner tip of a gold cone inserted in a fuel shell. An intense laser is then focused on the foam to generate hot electrons for the fast ignition. Element experiments demonstrate increased laser energy coupling efficiency into hot electrons without increasing the electron temperature and beam divergence with foam coated targets in comparison with solid targets. This may enhance the laser energy deposition in the compressed fuel plasma.

It is known that nerve fibers containing neuropeptides such as galanin increase in the periodontal ligament during experimental tooth movement. However, the origin of galanin-containing nerve fibers in the periodontal ligament remains unclear. This study was conducted to examine our hypothesis that the increased galanin nerve fibers have a sensory neuronal origin, and that the peptide is associated with pain transmission and/or periodontal ligament remodeling during experimental tooth movement. In control rats, galanin-immunoreactive trigeminal ganglion cells were very rare and were observed predominantly in small ganglion cells. After 3 days of experimental tooth movement, galanin-immunoreactive trigeminal ganglion cells significantly increased, and the most marked increase was observed at 5 days after experimental tooth movement. Furthermore, their cell size spectrum also significantly changed after 3 and 5 days of movement: Medium-sized and large trigeminal ganglion cells began expressing, and continued to express, galanin until 14 days after experimental tooth movement. These findings suggest that the increase of galanin in the periodontal ligament during experimental tooth movement at least partially originates from trigeminal ganglion neurons and may play a role in pain transmission and/or periodontal remodeling.

Isochoric heating by electrons has been measured in the two limiting cases of small area thin foils with dominant refluxing and cone-long-wire geometry with negligible refluxing in the wire. Imaging of Cu K alpha fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68eV and 256eV are discussed. Laser power on target was typically 0.5 PW in 0.7ps. Heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a 30 degrees cone has been studied with the same diagnostic methods plus imaging of proton induced K alpha. Conversion efficiency to protons has been measured and modeled. Conclusions from the experiments, links to theoretical understanding and relevance to fast ignition are outlined.