Matter and Radiation at Extremes
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2020, 5(1) Column

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Matter and Radiation at Extremes 第5卷 第1期

Author Affiliations
Abstract
1 Key Laboratory of Pulsed Power, Institute of Fluid Physics, China Academy of Engineering Physics, P.O. Box 919-108, Mianyang 621999, China
2 Southwest University of Science and Technology, Mianyang City, Sichuan Province 621010, China
Jets are commonly observed astrophysical phenomena. To study the x-ray emission characteristics of jets, a series of radial foil Z-pinch experiments are carried out on the Primary Test Stand at the Institute of Fluid Physics, China Academy of Engineering Physics. In these experiments, x-ray emission ranging from the soft region (0.1–10 keV) to the hard region (10 keV–500 keV) is observed when the magnetic cavity breaks. The radiation flux of soft x-rays is measured by an x-ray diode and the dose rate of the hard x-rays by an Si-PIN detector. The experimental results indicate that the energy of the soft x-rays is several tens of kilojoules and that of the hard x-rays is ~200 J. The radiation mechanism of the x-ray emission is briefly analyzed. This analysis indicates that the x-ray energy and the plasma kinetic energy come from the magnetic energy when the magnetic cavity breaks. The soft x-rays are thought to be produced by bremsstrahlung of thermal electrons (~100 eV), and the hard x-rays by bremsstrahlung of super-hot electrons (~mega-electron-volt). These results may be helpful to explain the x-ray emission by the jets from young stellar objects.
Matter and Radiation at Extremes
2020, 5(1): 014401
Author Affiliations
Abstract
1 School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, People’s Republic of China
2 Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, People’s Republic of China
3 Science and Technology on Plasma Physics Laboratory, Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900, People’s Republic of China
4 Institute of Applied Physics and Computational Mathematics, Beijing, 100094, People’s Republic of China
5 HEDPS, Center for Applied Physics and Technology, Peking University, Beijing 100871, People’s Republic of China
6 IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China
7 Graduate School, China Academy of Engineering Physics, P.O. Box 2101, Beijing 100088, People’s Republic of China
Powerful lasers interacting with solid targets can generate intense electromagnetic pulses (EMPs). In this study, EMPs produced by a pulsed laser (1 ps, 100 J) shooting at CH targets doped with different titanium (Ti) contents at the XG-III laser facility are measured and analyzed. The results demonstrate that the intensity of EMPs first increases with Ti doping content from 1% to 7% and then decreases. The electron spectra show that EMP emission is closely related to the hot electrons ejected from the target surface, which is confirmed by an analysis based on the target–holder–ground equivalent antenna model. The conclusions of this study provide a new approach to achieve tunable EMP radiation by adjusting the metal content of solid targets, and will also help in understanding the mechanism of EMP generation and ejection of hot electrons during laser coupling with targets.
Matter and Radiation at Extremes
2020, 5(1): 017401
Author Affiliations
Abstract
Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203, China
Metal halide perovskites (HPVs) have been greatly developed over the last decade, with various compositions, dimensionalities, and morphologies, leading to an emergence of high-performance photovoltaic and optoelectronic applications. Despite the tremendous progress made, challenges remain, which calls for a better understanding of the fundamental mechanisms. Pressure, a thermodynamic variable, provides a powerful tool to tune materials’ structures and properties. In combination with in situ characterization methods, high-pressure research could provide a better fundamental understanding. In this review, we summarize the recent studies of the dramatic, pressure-induced changes that occur in HPVs, particularly the enhanced and emergent properties induced under high pressure and their structure-property relationships. We first introduce the characteristics of HPVs and the basic knowledge of high-pressure techniques, as well as in situ characterization methods. We then discuss the effects of pressure on HPVs with different compositions, dimensionalities, and morphologies, and underline their common features and anomalous behaviors. In the last section, we highlight the main challenges and provide suggestions for possible future research on high-pressure HPVs.
Matter and Radiation at Extremes
2020, 5(1): 018201
Author Affiliations
Abstract
Department of Chemistry, Institute of Shock Physics, and Materials Science and Engineering, Washington State University, Pullman, Washington 99164, USA
Recent advances in high-pressure technologies and large-scale experimental and computational facilities have enabled scientists, at an unprecedented rate, to discover and predict novel states and materials under the extreme pressure-temperature conditions found in deep, giant-planet interiors. Based on a well-documented body of work in this field of high-pressure research, we elucidate the fundamental principles that govern the chemistry of dense solids under extreme conditions. These include: (i) the pressure-induced evolution of chemical bonding and structure of molecular solids to extended covalent solids, ionic solids and, ultimately, metallic solids, as pressure increases to the terapascal regime; (ii) novel properties and complex transition mechanisms, arising from the subtle balance between electron hybridization (bonding) and electrostatic interaction (packing) in densely packed solids; and (iii) new dense framework solids with high energy densities, and with tunable properties and stabilities under ambient conditions. Examples are taken primarily from low-Z molecular systems that have scientific implications for giant-planet models, condensed materials physics, and solid-state core-electron chemistry.
Matter and Radiation at Extremes
2020, 5(1): 018202
Author Affiliations
Abstract
1 Lawrence Livermore National Laboratory, Livermore, California 94551, USA
2 University of Rochester, Rochester, New York 14627, USA
3 SLAC National Accelerator, Menlo Park, California 94025, USA
4 University of California Berkeley, Berkeley, California 94720, USA
Over the last six years many experiments have been done at the National Ignition Facility to measure the Hugoniot of materials, such as CH plastic at extreme pressures, up to 800 Mbar. The “Gbar” design employs a strong spherically converging shock launched through a solid ball of material using a hohlraum radiation drive. The shock front conditions are characterized using x-ray radiography. In this paper we examine the role of radiation in heating the unshocked material in front of the shock to understand the impact it has on equation of state measurements and how it drives the measured data off the theoretical Hugoniot curve. In particular, the two main sources of radiation heating are the preheating of the unshocked material by the high-energy kilo-electron-volt x-rays in the hohlraum and the heating of the material in front of the shock, as the shocked material becomes hot enough to radiate significantly. Using our model, we estimate that preheating can reach 4 eV in unshocked material, and that radiation heating can begin to drive data off the Hugoniot significantly, as pressures reach above 400 Mb.
Matter and Radiation at Extremes
2020, 5(1): 018401
Author Affiliations
Abstract
1 Lamont-Doherty Earth Observatory, Columbia University, Palisades New York 10964, USA
2 Earth and Environmental Sciences, University of Michigan, Ann Arbor Michigan 48109, USA
Castable solids from Aremco (http://www.aremco.com/potting-casting-materials/) are convenient media for pressure transmission in multianvil geometries of complex shape. A zirconia-based castable ceramic, Aremco Ceramacast 646, is introduced and compared to MgO-Al2O3-SiO2-based Aremco Ceramacast 584. Ceramacast 646 has some advantages over the widely used Ceramacast 584; these include ease of consistent fabrication and better thermal insulation. Some disadvantages are poorer efficiency in converting press thrust to sample pressure and slower quenching rates. Potential applications are informed by these differences.
Matter and Radiation at Extremes
2020, 5(1): 018402
Author Affiliations
Abstract
1 Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan
2 Department of Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan
3 Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan
4 Center of Science and Technology Under Extremes Conditions, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan
5 Department of Earth Science, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
An overview of the recently renovated high-pressure X-ray diffraction (XRD) BL10XU beamline for the diamond anvil cell at SPring-8 is presented. The renovation includes the replacement of the X-ray source and monochromator, enhanced focusing systems for high-energy XRD, and recent progress in the sample environment control techniques that are available for high-pressure studies. Other simultaneous measurement techniques for combination with XRD, such as Raman scattering spectroscopy and M?ssbauer spectroscopy, have been developed to obtain complementary information under extreme conditions. These advanced techniques are expected to make significant contributions to in-depth understanding of various and complicated high-pressure phenomena. The experience gained with the BL10XU beamline could help promote high-pressure research in future synchrotron radiation facilities.
Matter and Radiation at Extremes
2020, 5(1): 018403

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