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Laser–plasma interaction and hot electrons have been characterized in detail in laser irradiation conditions relevant for direct-drive inertial confinement fusion. The experiment was carried out at the Gekko XII laser facility in multibeam planar target geometry at an intensity of approximately $3\times {10}^{15}$ W/cm2. Experimental data suggest that high-energy electrons, with temperatures of 20–50 keV and conversion efficiencies of $\eta , were mainly produced by the damping of electron plasma waves driven by two-plasmon decay (TPD). Stimulated Raman scattering (SRS) is observed in a near-threshold growth regime, producing a reflectivity of approximately $0.01\%$ , and is well described by an analytical model accounting for the convective growth in independent speckles. The experiment reveals that both TPD and SRS are collectively driven by multiple beams, resulting in a more vigorous growth than that driven by single-beam laser intensity.

When a laser is focused on an underwater object, it experiences a large amount of pressure owing to the plasma confinement effect of water. A hemispherical bubble is generated on the surface of the object, and large pressure is generated when the bubble collapses. In this study, we conducted experiments using different laser energies to analyze the pressure–time histories associated with bubble contraction. The maximum pressure was 10%–40% of the laser ablation pressure, whereas the pressure pulse width was 5–10 times longer than the laser pulse width. Furthermore, the bubble motion could be adiabatically explained, except for the plasma interaction region. The results indicate that the pressure at which the bubble collapses does not depend on the maximum size of the generated bubble but depends on the energy of water vapor within the bubble.

T. Tamagawa, Y. Hironaka, K. Kawasaki, D. Tanaka, T. Idesaka, N. Ozaki, R. Kodama, R. Takizawa, S. Fujioka, A. Yogo, D. Batani, Ph. Nicolai, G. Cristoforetti, P. Koester, L. A. Gizzi, and K. Shigemori, "Development of an experimental platform for the investigation of laser–plasma interaction in conditions relevant to shock ignition regime", Review of Scientific Instruments 93, 063505 (2022) https://doi.org/10.1063/5.0089969, The shock ignition (SI) approach to inertial confinement fusion is a promising scheme for achieving energy production by nuclear fusion. SI relies on using a high intensity laser pulse (≈1016 W/cm2, with a duration of several hundred ps) at the end of the fuel compression stage. However, during laser-plasma interaction (LPI), several parametric instabilities, such as stimulated Raman scattering and two plasmon decay, nonlinearly generate hot electrons (HEs). The whole behavior of HE under SI conditions, including their generation, transport, and final absorption, is still unclear and needs further experimental investigation. This paper focuses on the development of an experimental platform for SI-related experiments, which simultaneously makes use of multiple diagnostics to characterize LPI and HE generation, transport, and energy deposition. Such diagnostics include optical spectrometers, streaked optical shadowgraph, an x-ray pinhole camera, a two-dimensional x-ray imager, a Cu Kα line spectrometer, two hot-electron spectrometers, a hard x-ray (bremsstrahlung) detector, and a streaked optical pyrometer. Diagnostics successfully operated simultaneously in single-shot mode, revealing the features of HEs under SI-relevant conditions.

In situ femtosecond x-ray diffraction measurements and ab initio molecular dynamics simulations were performed to study the liquid structure of tantalum shock released from several hundred gigapascals (GPa) on the nanosecond timescale. The results show that the internal negative pressure applied to the liquid tantalum reached $\ensuremath{-}5.6\text{ }(0.8)\text{ }\text{ }\mathrm{GPa}$, suggesting the existence of a liquid-gas mixing state due to cavitation. This is the first direct evidence to prove the classical nucleation theory which predicts that liquids with high surface tension can support GPa regime tensile stress.

In this work, we present experimental results on the behavior of liquid water at megabar pressure. The experiment was performed using the HIPER (High-Intensity Plasma Experimental Research) laser facility, a uniaxial irradiation chamber of GEKKO XII (GXII) at the Institute of Laser Engineering (ILE), and the PHELIX at GSI (GSI Helmholtz Centre for Heavy Ion Research), a single-beam high-power laser facility, to launch a planar shock into solid multilayered water samples. Equation-of-state data of water (H2O) are obtained in the pressure range 0.50–4.6 Mbar by tuning the laser-drive parameters. The Hugoniot parameters (pressure, density, etc.) and the shock temperature were simultaneously determined by using VISAR and SOP as diagnostic tools and quartz as the standard material for impedance mismatch experiments. Finally, our experimental results are compared with hydrodynamic simulations tested with different equations of state, showing good compatibility with tabulated SESAME tables for water., The authors would like to acknowledge the support of the laser technical team at GEKKO XII (ILE) and PHELIX (GSI). This work received funding from the Euratom Research and Training Program 2014–2018 and 2019-2020 (Grant agreement no. 633053). The involved teams were operated within the framework of the Enabling Research Project ENR-IFE19.CEA-01, Study of Direct Drive and Shock Ignition for IFE: Theory, Simulations, Experiments, Diagnostics Development. JIHT RAS team members were supported by the Ministry of Science and Higher Education of the Russian Federation (State Assignment no. 075-00460-21-00).

Diamond is a promising alternative capsule material for direct-drive inertial confinement fusion. Previous investigations suggest that the stiffness and higher density of diamond can mitigate laser imprinting, which is an initial perturbation on the ablation surface caused by non-uniform laser irradiation. We conduct diamond capsule fabrication using the hot filament chemical vapor deposition (HF-CVD) technique. This technique is the most suitable diamond deposition method in terms of mass production, since the deposition area can be easily extended just by increasing the number of hot filaments. This paper presents the first direct-drive implosion experiment concerning diamond capsules fabricated using the HF-CVD technique. The compression of thin diamond capsules, with an inner capsule diameter of 482 μm and a shell thickness of 1.6 μm, is successfully achieved, and the implosion trajectory of diamond capsules, with the same diameter and thickness, is consistent with 1D radiation hydrodynamic simulation calculations. However, for diamond capsules with an inner diameter of 482 μm and a shell thickness of 2.4 μm, asymmetry of the implosion trajectory and unexpected x-ray emission are observed. This is attributed to the remaining silicon (Si) mold inside the capsule left over from the fabrication process, revealing that the etching method of Si in diamond capsules should be improved.

In order to achieve the ignition by direct-drive inertial confinement fusion (ICF), smooth and symmetric fuel capsule is required. Our previous research found that stiffness of the capsule material contributes to reduce the laser imprinting. Therefore, diamond is considered to be the most promising candidate as the stiff ablator material for direct-drive ICF capsule. In this study, aiming at improving the surface roughness on the diamond capsule, we obtained dependence of methane concentration and gas pressure on surface roughness and morphology by hot filament chemical vapor deposition technique.

Typical inertial confinement fusion (ICF) plasmas have ultra-high energy density state (UHEDs) with an energy density exceeding 1 × 108 Jcm−3, which corresponds to a pressure of beyond 1 Gbar. In previous investigation, it is suggested that such an UHEDs condition could be generated with a tabletop ultrahigh intensity laser, by irradiating onto a nanowire array. In this research, we have developed to observe the laser energy absorption and transport mechanism in nanowire array samples with x-ray free electron laser facility SACLA. We obtained time-resolved snapshots of x-ray shadowgraph image with very high temporal resolution. From the measured images, however, the UHEDs might be generated only on very thin portion of the target surface because the mean density of the nanowire array was large. On the other hand, we observed significant rear surface expansion in late timing, suggesting that large laser energy deposition was achieved for the nanowire array samples.

The fast ignition realization experiment (FIREX) project is progressing. The new short pulse laser system, LFEX laser, has been completely assembled and one of the four beamlets is now in operation. A fast-ignition experiment was performed using this single short pulse combined with the Gekko XII implosion laser. The energy of the GXII implosion laser was about 2 kJ and the pulse width was 1.5 ns. The energy of the LFEX laser was increased upto 800 J and two pulse durations 5 and 1.6 ps were compared. Targets were deuterated plastic shells with gold cones. It was found that the neutron yield was increased by a factor of 30 as a result of the fast electron-induced heating in LFEX 1.6 ps shot. The estimated coupling efficiency between the LFEX laser pulse and the compressed fuel was low (less than 5%). This may be due to pre-plasma formed by light arriving at the target before the main laser pulse. Further investigations and attempts to overcome these problems are now in progress. © 2011 Elsevier B.V.

A novel custom-developed scintillator for laser fusion diagnostics is reported. With the aim of diagnosing scattered neutrons from the imploded high-density fusion plasma, a fast response lithium-6 glass scintillator has been developed. Praseodymium, instead of the more widely-used cerium was chosen as the dopant. Sufficiently fast luminescence lifetime for scattered neutron diagnostics (

We present herein a comprehensive study of how the equation of state affects laser imprinting by nonuniform laser irradiation of an inertial fusion target. It has been suggested that a stiffer and denser material would reduce laser imprinting based on the equation of motion with pressure perturbation. We examine the detailed temporal evolution of the imprint amplitude by using the two-dimensional radiation hydrodynamic simulation PINOCO-2D for diamond, which is a candidate stiff-ablator material for inertial fusion targets. The simulated laser imprinting amplitude is compared with experimental measurements of areal-density perturbations obtained by using face-on x-ray backlighting for diamond and polystyrene (PS) (the latter as a reference). The experimental results are well reproduced by the results of the PINOCO-2D simulation, which indicates that the imprinting amplitude due to nonuniform irradiation (average intensity, 4.0 × 1012 to 5.0 × 1013) differs by a factor of two to three between diamond and PS. The difference in laser imprinting is mainly related to the material density and compressibility. These parameters are key factors that determine the laser imprinting amplitude.

A new type of cluster ion beam system using organic liquid materials such as ethanol has been developed, and it has several advantages for surface etching and chemical modification based on the different properties of liquid cluster ions. Ethanol vapors were ejected through a nozzle into a high-vacuum region, and ethanol clusters were produced by an adiabatic expansion phenomenon at the vapor pressures larger than 1 atm. In another case of producing ethanol clusters at a lower vapor pressure, He gas was used to mix up with ethanol vapors, and the mixed gases were ejected into a high vacuum region. Even if a vapor pressure of ethanol was 0.1 atm, ethanol clusters were produced at the He gas pressure larger than 1 atm. The ethanol clusters produced were ionized by an electron bombardment method, and the cluster ions were accelerated toward a substrate by applying an acceleration voltage. For the case of ethanol cluster ion irradiation at an acceleration voltage of 9 kV, the sputtering yields for Al, Cu, Ag and Au films, which were used as a substrate, were about ten times larger than that by Ar monomer ion irradiation. In addition, the surface flatness of the metal films was improved by irradiation of ethanol cluster ions.

A combined experimental and numerical study of interaction between cooling flow and mainstream gas flow in a turbine rotor-stator rim cavity is reported. Particular emphasis is put on the flow phenomena in a rim cavity downstream of rotor blades. The experiments are conducted on a rig simulating a engine HP-turbine in which cooling effectiveness distributions as well as velocities, turbulence quantities, pressure and temperature profiles are measured. Numerical calculation, especially at a full 3D, unsteady solution level, can lead to satisfactory predictions in fluid and mass transfer inside the cavity. Both experimental and numerical results indicate that large turbulence stresses near the rotor disk intensify turbulent diffusion across the cavity and consequently axial distribution of the cooling effectiveness inside the cavity becomes uniform. In order to obtain an adequate distribution of cooling effectiveness across the rim cavity and to suppress the turbulence level near the rotor surface for more efficient cooling, a novel cooling method is developed using numerical simulation. The disk-front and -rear cavities are then redesigned according to the new cooling strategy and integrated in the test rig. Experimental results verify a significant advance in cooling performance with the new method.Copyright © 2004 by ASME

The study of fast electron spectrum optimization by suppression of preformed plasma in fast ignition targets is presented in this work. Integrated fast-electron spectra for electron energies below 3 MeV—the energy range responsible for core heating—are compared for different preformed plasma conditions. The pulse contrast (the ratio of peak-to-pedestal laser intensities) is compared for 108, 109 and 1011 conditions at constant laser energy (~500 J), pulse duration (2 ps), spot size (30% encircled energy on 50 µm diameter) and laser intensity (around 1 × 1019 W cm−2). The best electron spectrum optimization, consisting of maximized electron number for energies below 3 MeV was obtained with 14 µm thick cone targets. The energy coupling efficiency from heating laser to core plasma, assuming typical core plasma parameters, was estimated to be 2%, although 0.37% was obtained with previous conditions with poor pulse contrast and a 7 µm thick cone target.

著者人数: 20名, 資料番号: SA1002901000

Flyer acceleration technique using high-power lasers has several advantages such as the achieved velocities higher than 10 km/s and non-contamination to the products generated by impacts. In this study, we show that a high-power laser can achieve flyer velocities higher than 10 km/s up to 60 km/s using spherical projectiles with a diameter of 0.1 − 0.3mm. We discuss the projectile condition during the flight based on the results of numerical simulations.

We have been developing an alternative scheme of fast ignition of inertial confinement targets with converging shock. Experiments were carried out on GEKKO-XII laser facility at ILE, Osaka University. We employed Au cone targets filled with low- density RF foam (2 mg/cm3). The foam-filled cone targets were irradiated by three beams of the GEKKO-XII, with pulse duration of 1.3 ns, intensity of ~ 1014 W/cm2 in 2 :λ(ω0.527μm). Self-emission at the tip of cone was observed by one-dimensional streaked optical pyrometer (SOP) and two-dimensional images.

Developments in measuring sound velocity of matter under ultrahigh pressure are described. We employed a time-resolved x-ray shadowgraph technique to measure the sound velocity of shock-compressed diamond and iron foils at around melt. The sound velocity significantly dropped at melting, a behavior that has been difficult to clarify by conventional measurements by subtracting particle velocity from shock velocity (u(s) - u(p)). In addition to sound velocity, other important parameters were also obtained simultaneously.

A custom developed (6)Li glass scintillator (APLF80+3Pr) for down-scattered neutron diagnostics in inertial confinement fusion experiments is presented. (6)Li provides an enhanced sensitivity for down-scattered neutrons in DD fusion and its experimentally observed 5-6 ns response time fulfills the requirement for down-scattered neutron detectors. A time-of-flight detector operating in the current mode using the APLF80+3Pr was designed and its feasibility observing down-scattered neutrons was demonstrated. Furthermore, a prototype design for a down-scattered neutron imaging detector was also demonstrated. This material promises viability as a future down-scattered neutron detector for the National Ignition Facility.

This paper describes a prototype design and preliminary evaluation of a decentralized modular device network for wide-area monitoring, protection and control of power systems, utilizing off-the-shelf and standardized information and communications technologies (ICT). The prototype network consists of 100M/1Gbps L2 switch networks, device-embedded and external IEEE 1588-based time synchronizing schemes, and function- and application-based modular devices. Experimental results show that a time synchronization error of less than 1 microsecond between modular devices was achieved, and that the versatile implementation of applications such as wide-area current differential protection and state measurements was conducted successfully.

The relationship of gastric hypermotility to mucosal hemodynamics, lipid peroxidation and vascular permeability changes was investigated in the pathogenesis of indomethacin-induced gastric lesions in

The shock induced polarization is one model to explain the electromotive force (EMF) originated from the shock compressed material and provides a good explanation of the variation of the current from the sample with time. This model suggests that the dipole polarization is induced at the shock front and decay behind the front with some characteristic long relaxation time. The precise microscopic mechanism is still unknown. The amount of induced polarization generally depends on the shock pressure and the material. We report the shock induced electromotive forces for several phases of 4-methoxybenzylidene-4-n-butylaniline (MBBA) and the strong dependence of the magnitude of EMF on the initial state of this material.

In this paper, we performed the femtosecond time-resolved X-ray diffraction on the 60-fs laser irradiated a CdTe single crystal and detected the coherent longitudinal optical (LO) phonon (5.07 THz) at Brilliuon zone center. The coherent LO phonon is also confirmed by using an optical reflectivity measurement

Electroluminescent (EL) diodes utilizing poly(3-alkylthiophene) (P3AT) containing fluorescent dyes have been fabricated. It has more than 500 times higher EL efficiency in P3AT diodes doped with (1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene) (PPCP) than in undoped diode. The mechanism of emission enhancement in P3AT diodes with different alkyl side chains has been discussed in terms of carrier confinement and energy band diagram.

Characterization of 5500 V-class reverse conducting SI-thyristors as a pulsed power switching device was examined utilizing a low inductance testing circuit. The testing circuit consisted of nineteen doorknob type ceramic capacitors with the total capacitance of 38 nF, and had a residual inductance of less than 13 nH. The SI-thyristor, tested in this report, was specially designed for pulsed power applications. When the anode voltage of 5 kV was applied, a discharge current rose up to 4.2 kA with dl/dt of 6.8/spl times/10/sup 10/ A/s, and the anode voltage fall time reached 62 ns. The comparison with conventionally designed SI-thyristors indicated the effectiveness of the new design.

Direct observation of lattice dynamics of a 300 ps laser irradiated silicon crystal is performed by means of picosecond time‐resolved X‐ray diffraction. Change in X‐ray diffraction profiles corresponds to propagation of a strain pulse inside the sample with sound velocity. The strain profiles are simulated by considering carrier dynamics and thermo‐elastic treatment.

A 77-year-old female presented with a giant aneurysm of the azygos anterior cerebral artery (ACA) manifesting as acute onset of akinetic mutism caused by enlargement of the aneurysm resulting from rapid thrombus formation within the aneurysmal sac. Thrombus removal to obtain decompression of the aneurysmal bulk and tension was performed before parent artery occlusion to prevent thromboembolic events. The aneurysmal neck was completely clipped with preservation of the parent artery and all branches. This strategy for direct neck clipping of a giant thrombosed distal ACA aneurysm can reduce the possibility of ischemic sequelae.

In 1995, we proposed a non-destructive type of three-stage light-gas gun having an additional preheating and filling stage which allows to regulate in a broad range the initial energy of working gas. Installation and preliminary tests of the system were almost completed. In several shots as a conventional two-stage light-gas gun with unheated helium gas, a velocity of 6.49 km/s was achieved for 1.7-g projectile. In preheating tests, a 9.5-kg pre-pump piston was reusable under the condition in which He-gas was preheated to 1080 K by compressed air of 106 Pa. A relaxation time of heat conduction loss through the pre-pump wall was estimated to be 96 ms from the pressure profile of He-gas confined. In the case of powder, the peak temperature of He was achieved to the value of isentropic compression, 1300 K, and was in good agreement with the value estimated from the sound velocity. From simulation, we propose the concept of operational mode limits that is the difficulty to regulate pressure/temperature profil...

Shock induced polarization is one model used to explain the electromotive forces originating from shock compressed materials. This model supposes that dipoles are induced at the shock front and decay behind the front with a characteristic relaxation time. The resulting polarization is sensed with an oscilloscope which measures the current flowing between two electrodes surrounding the sample being shocked. The polarization model provides a good explanation of the variation of the current from this capacitor with time. Here, we report the shock induced electromotive forces for two classes of materials: several phases of 4-methoxybenzylidene-4-n-butylaniline (MBBA) and dilute solutions of electrolytes in water. These cases shows a strong dependence of the signals on material composition and phase.

We have tested a scheme for using laser implosion plasmas to generate pressures in the gigabar (100 TPa) regime. Cone-in-shell targets employed in fast ignition of inertial confinement fusion were irradiated to create a high-pressure source for compression of materials. The imploded plasmas pushed a foil embedded on the tip of a cone. The pressure was estimated from the shock velocity into the material; the shock velocity was obtained from an optical measurement. The measured shock velocity of the foil was above 100 km/s, corresponding to a pressure greater than 1 Gbar.

A three-stage light-gas gun having a preheating and filling stage of gas was designed and installed in order to independently regulate the initial energy of the light gas. Although the operation and the performance of gun become so complicated, the computer simulations for the gun indicate many advantages, e.g., a scale of the gun much decreases in comparison with a conventional two-stage light-gas gun at the same value of the maximum obtainable projectile velocity.

The world's largest peta watt (PW) laser LFEX, which delivers energy up to 2?kJ in a 1.5?ps pulse, has been constructed beside the GEKKO XII laser at the Institute of Laser Engineering, Osaka University. The GEKKO-LFEX laser facility enables the creation of materials having high-energy-density which do not exist naturally on the Earth and have an energy density comparable to that of stars. High-energy-density plasma is a source of safe, secure, environmentally sustainable fusion energy. Direct-drive fast-ignition laser fusion has been intensively studied at this facility under the auspices of the Fast Ignition Realization Experiment (FIREX) project.In this paper, we describe improvement of the LFEX laser and investigations of advanced target design to increase the energy coupling efficiency of the fast-ignition scheme. The pedestal of the LFEX pulse, which produces a long preformed plasma and results in the generation of electrons too energetic to heat the fuel core, was reduced by introducing an amplified optical parametric fluorescence quencher and saturable absorbers in the front-end system of the LFEX laser. Since fast electrons are scattered and stopped by the strong electric field of highly ionized high-Z (i.e. gold) ions, a low-Z cone was studied for reducing the energy loss of fast electrons in the cone tip region. A diamond-like carbon cone was fabricated for the fast-ignition experiment. An external magnetic field, which is demonstrated to be generated by a laser-driven capacitor-coil target, will be applied to the compression of the fuel capsule to form a strong magnetic field to guide the fast electrons to the fuel core. In addition, the facility offers a powerful means to test and validate astronomical models and computations in the laboratory. As well as demonstrating the ability to recreate extreme astronomical conditions by the facilities, our theoretical description of the laboratory experiment was compared with the generally accepted explanation for astronomical observations.

Hydrogen at high pressure in the fluid state is of great interest for target design of inertial confinement fusion and understanding the interior structure of gas giant planets. In this work, we successfully obtained the Hugoniot data for liquid hydrogen up to 55 GPa under laser-driven shock loading using impedance matching to a quartz standard. The shocked temperature was determined simultaneously by the brightness temperature. The compression and temperature along the principal Hugoniot are in good agreement with theoretical models. High reflectivity of hydrogen was observed at 40 GPa, which suggests the fluid becomes conducting.

[1] The impact velocities of asteroids on Earth and other terrestrial planets can be greater than 10 km/s, and impacts at these high velocities can produce significant effects on the planetary surfaces. However, since macroscopic (>∼0.1 mm) projectiles with an aspect ratio of ∼1 are not easily accelerated to more than 10 km/s in laboratories, there are few detailed experimental studies. In this paper, we demonstrate that impact velocities greater than 10 km/s can be achieved with glass and aluminum projectiles of 0.1–0.3 mm in diameter using a high-power laser, GEKKO XII-HIPER at Institute of Laser Engineering, Osaka University. The velocity of the projectiles is estimated based on the images taken by high-speed X-ray streak and framing cameras. Projectiles collide into copper or LiF plate targets. The copper plates are recovered for analysis. The sizes of craters on the copper plates are not far from the extrapolations from previous work with lower velocities. A tantalum witness plate placed near the copper plates records a large number of secondary craters from each impact. In the case of the impacts of the LiF plates, we observe two emission lines of Li gas using a spectrometer with a streak camera. Thus, we can simulate the hypervelocity impacts with velocities higher than 10 km/s in laboratories.

This paper reports an experimental study on preheating of laser-irradiated targets. We performed temperature measurements at the rear surface of laser-irradiated targets under conditions of two different laser wavelengths (0.35 or 0.53 μm) and several intensities (2×1013–1×1014 W/cm2) in order to verify an effect of radiation and nonlocal electron heat transport. The preheating temperature was evaluated by observing self-emission, reflectivity, and expansion velocity at the rear surface of planar polyimide foils. The experimental results show that the x-ray radiation is dominant for preheating for 0.35-μm laser irradiation, but contribution of nonlocal electron heat transport is not negligible for 0.53-μm laser irradiation conditions.

Equation-of-state data, not only pressure and density but also temperature, for polystyrene (CH) are obtained up to 510 GPa. The region investigated in this work corresponds to an intermediate region, bridging a large gap between available gas-gun data below 60 GPa and laser shock data above 500 GPa. The Hugoniot parameters and shock temperature were simultaneously determined by using optical velocimeters and pyrometers as the diagnostic tools and the α-quartz as a new standard material. The CH Hugoniot obtained tends to become stiffer than a semiempirical chemical theoretical model predictions at ultrahigh pressures but is consistent with other models and available experimental data.

The relationship of gastric hypermotility to mucosal hemodynamics, lipid peroxidation and vascular permeability changes was investigated in the pathogenesis of indomethacin-induced gastric lesions in rats. Subcutaneous administration of indomethacin (25 mg/kg) produced an increase in both the amplitude and frequency of stomach contraction from 30 min after treatment, resulting in hemorrhagic damage 2 h later. Gastric mucosal blood flow measured by a Laser flowmetry showed oscillatory fluctuations under hypercontractile states: a decrease during contraction followed by an increase during relaxation. Mucosal lipid peroxidation and vascular permeability were significantly increased with time after indomethacin treatment, and these changes preceded the appearance of hemorrhagic damage. All these events were prevented when gastric hypermotility was inhibited by atropine or 16,16-dimethyl prostaglandin E2. Pretreatment of the animals with allopurinol and hydroxyurea or continuous infusion of superoxide dismutase and dimethyl sulfoxide during a test period also attenuated these functional changes and mucosal lesions induced by indomethacin, without affecting the motility response. We conclude that oxygen free radicals may play a role in the development of mucosal lesions associated with gastric hypermotility in indomethacin-treated rats.

Experiments on shock compression of diamond foils with intense laser are reported. In order to explore high-pressure and low-temperature region of the carbon phase-diagram, we irradiate single-crystal (Type-Ib) crystal foils with a shaped (ramp) pulse at the pressure of over 1TPa. We observed time-resolved reflectivity from the rear surface of the diamond during the shock compression with velocity interferometer system for any reflector (VISAR). Simultaneous observation of optical measurements and x-ray diffraction has been tested. Preliminary results on decompression of the diamond crystal due to x-ray heating were observed.

We have proposed a new ignition scheme of Fast Ignition, called 'Impact Fast Ignition [1] (IFI)', in which a compressed fuel is ignited by impact collision of a fragment of separately imploded fuel. We have started experiments that used CD colliding foils as the fundamental experiment and integrated experiment of the IFI. In the fundamental experiment, we used targets which are consists of two CD foils (thickness of 20 μm) with a 600 μm separation. We have irradiated one of the CD foils by laser beams of the energy of 2 kJ in total and accelerated. The accelerated CD foil collides with another foil, and neutrons were generated by the nuclear fusion reaction on the heated foil. In this experiment, we measured the neutron yield of 106. In the integrated experiment, we used CD shell targets with a gold cone which had a hemispherical impactor (Fig. 1). The shell was imploded using 9 beams and the impactor was accelerated using 3 beams of the GEKKO XII laser system. The laser energy was 350 J per beam. Observed maximum neutron yield was 2 × 106. This yield was 80 times as large as that without impactor. We will present the experimental details and results.

To elucidate 1-carnitine chloride effects ischemic myocardium for the possibility of a salvage of risk zone around necrosis in myocardial infarcts of dogs, a quantitative evaluation of the extent of myocardial infarcts was done by size detection with use of monastral blue and tissue dehydrogenase histochemistry at 20 hours after coronary ligation. The results show that the ratio of unsalvaged infarct zone to occluded coronary bed is 85.3 +/- 2.9% in the control group, while it is 53.2 +/- 3.6% in the 1-carnitine administered (1 C) group. The difference between these ratios is statistically significant (p less than 0.01). The results also indicate significantly lower serum CPK concentration. Therefore, carnitine may play a role in preventing a size extention of infarcts through improving an altered lipid metabolism, particularly a fatty acid metabolism, of myocardial cells in the risk zone.