Graphite and hexagonal boron nitride (h-BN), despite their structural similarity, exhibit opposing electronic properties, namely, metallic conductivity and wide-bandgap insulation, respectively. In recent years, graphene-h-BN heterostructures have attracted significant research interest, with the resulting hybrid B–C–N atomic-layer systems exhibiting distinctive electronic properties. Notably, interface effects play a decisive role in governing the performance of these heterostructures. Nevertheless, owing to the lack of high-quality composites, the interfacial structure in B–C–N materials and the correlation with critical properties such as charge transport and band structure modulation are not fully clear. Here, we report the direct synthesis of a millimeter-sized hexagonal B–C–N composite via a solvent method under high-pressure and high-temperature conditions. Structural characterization reveals that the synthesized B–C–N composite contains isolated graphite and h-BN. Compared with pure h-BN, the B–C–N composite has a narrower bandgap and shows a pronounced photoelectric response in the visible light region. More interestingly, we find a graphite-like B–C compound with a thickness of about 30 nm at the graphite–h-BN interface, which forms Schottky junctions with graphite, thus realizing rectification properties. Our findings provide a method for synthesizing high-quality B–C–N composites and offer new insights into the structure of the graphite–h-BN interface.
{"title":"Hexagonal B–C–N composite consisting of <i>h</i> -BN and graphite separated by B–C nanolayer","authors":"Baoyin Xu, Xiaohong Yuan, Bingtao Feng, Yifeng Jiang, Yaqi She, Zhanhui Ding, Yue Pan, Shitao Liu, Kuo Hu, Zhaodong Liu, Quanjun Li, Bingbing Liu, Hu Tang","doi":"10.1063/5.0302494","DOIUrl":"https://doi.org/10.1063/5.0302494","url":null,"abstract":"Graphite and hexagonal boron nitride (h-BN), despite their structural similarity, exhibit opposing electronic properties, namely, metallic conductivity and wide-bandgap insulation, respectively. In recent years, graphene-h-BN heterostructures have attracted significant research interest, with the resulting hybrid B–C–N atomic-layer systems exhibiting distinctive electronic properties. Notably, interface effects play a decisive role in governing the performance of these heterostructures. Nevertheless, owing to the lack of high-quality composites, the interfacial structure in B–C–N materials and the correlation with critical properties such as charge transport and band structure modulation are not fully clear. Here, we report the direct synthesis of a millimeter-sized hexagonal B–C–N composite via a solvent method under high-pressure and high-temperature conditions. Structural characterization reveals that the synthesized B–C–N composite contains isolated graphite and h-BN. Compared with pure h-BN, the B–C–N composite has a narrower bandgap and shows a pronounced photoelectric response in the visible light region. More interestingly, we find a graphite-like B–C compound with a thickness of about 30 nm at the graphite–h-BN interface, which forms Schottky junctions with graphite, thus realizing rectification properties. Our findings provide a method for synthesizing high-quality B–C–N composites and offer new insights into the structure of the graphite–h-BN interface.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"11 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147894107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shaojie Wang, Mingtao Li, Zhongyan Wu, Saichao Cao, Penghui Li, Xiang Zhang, Zhiwei Shen, Hongkai Li, Ke Yang, Li Zhang, Guoying Gao, Lin Wang, Yongjun Tian
Recent advances in geoscience have underscored the critical role of abiogenic processes in petroleum formation, especially the formation and polymerization of methane. However, whether a direct carbon–H2 reaction can produce C2+ hydrocarbons (e.g., ethane and propane) beyond methane remains an open question. Here, we demonstrate the direct synthesis of ethane and propane via reactions between amorphous carbon and H2 under upper mantle conditions (2–10 GPa and 800–1200 °C). A systematic investigation reveals that increasing structural disorder in carbon precursors, from graphite to glassy carbon-II and carbon black, enhances the production of C2–C3 hydrocarbons. Through integrated X-ray diffraction and reverse Monte Carlo simulations, we establish that the continuous random atomic network structures in amorphous carbon enable one-step synthesis of heavy hydrocarbons with H2. These models establish a direct link between atomic-scale carbon structures and the one-step synthesis of C2+ hydrocarbons under H2-rich, high-pressure, and high-temperature conditions—potentially revealing an efficient mechanism for the abiotic production of C2+ hydrocarbons in the upper mantle.
{"title":"Structural disorder-driven synthesis of C2+ hydrocarbons via direct hydrogenation of amorphous carbon with continuous random atomic networks","authors":"Shaojie Wang, Mingtao Li, Zhongyan Wu, Saichao Cao, Penghui Li, Xiang Zhang, Zhiwei Shen, Hongkai Li, Ke Yang, Li Zhang, Guoying Gao, Lin Wang, Yongjun Tian","doi":"10.1063/5.0293989","DOIUrl":"https://doi.org/10.1063/5.0293989","url":null,"abstract":"Recent advances in geoscience have underscored the critical role of abiogenic processes in petroleum formation, especially the formation and polymerization of methane. However, whether a direct carbon–H2 reaction can produce C2+ hydrocarbons (e.g., ethane and propane) beyond methane remains an open question. Here, we demonstrate the direct synthesis of ethane and propane via reactions between amorphous carbon and H2 under upper mantle conditions (2–10 GPa and 800–1200 °C). A systematic investigation reveals that increasing structural disorder in carbon precursors, from graphite to glassy carbon-II and carbon black, enhances the production of C2–C3 hydrocarbons. Through integrated X-ray diffraction and reverse Monte Carlo simulations, we establish that the continuous random atomic network structures in amorphous carbon enable one-step synthesis of heavy hydrocarbons with H2. These models establish a direct link between atomic-scale carbon structures and the one-step synthesis of C2+ hydrocarbons under H2-rich, high-pressure, and high-temperature conditions—potentially revealing an efficient mechanism for the abiotic production of C2+ hydrocarbons in the upper mantle.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147898889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhang Yu-tian, Guoliang Niu, Pengfei Tan, Chuanhui Zhu, Huiyang Gou, David Walker, Man‐Rong Li
High-pressure and high-temperature (HPHT) experiments in large-volume presses (LVPs) benefit from reliable, available, and affordable heaters to achieve stable and homogeneous heating and, in some circumstances, X-ray transparency for monitoring of properties of an in situ experiment using X-ray diffraction and contrast imaging techniques. We have developed heaters meeting the above requirements, and we screen the ternary system TiB2–SiC–hexagonal (h)BN (denoted as TSB) to enable manufacture of X-ray transparent heaters for HPHT runs. Heaters fabricated using optimized TSB-631 (60%TiB2–30%SiC–10%hBN by weight) have been tested in modified truncated assemblies, showing excellent performance up to 22 GPa and 2395 K in HPHT runs. TSB-631 has good ceramic machinability, outstanding reproducibility, high stability, and negligible temperature gradient for runs at 3–7 GPa with cell assemblies with truncated edge lengths of 8–12 mm. The fabricated heaters not only show excellent performance in HPHT runs, but also demonstrate high X-ray transparency over a wide X-ray wavelength region, indicating potential applications for in situ X-ray diffraction/imaging under HPHT conditions in LVPs and other high-pressure apparatus.
大容量压机（lvp）中的高压高温（HPHT）实验得益于可靠、可用和价格合理的加热器，以实现稳定和均匀的加热，在某些情况下，使用x射线衍射和对比成像技术监测原位实验特性的x射线透明度。我们开发了满足上述要求的加热器，并筛选了tib2 - sic -六方(h)BN三元体系（表示为TSB），以制造用于高温高温运行的x射线透明加热器。使用优化的TSB-631 （60%TiB2-30%SiC-10%hBN重量）制造的加热器已经在改进的截尾组件中进行了测试，在高温下运行时表现出优异的性能，最高可达22 GPa和2395 K。TSB-631具有良好的陶瓷可加工性，出色的可重复性，高稳定性和可忽略不计的温度梯度，在3-7 GPa下运行，电池组件的截边长度为8-12 mm。所制备的加热器不仅在高温高压运行中表现出优异的性能，而且在宽x射线波长区域内表现出较高的x射线透明度，这表明了在LVPs和其他高压设备中高温高压条件下的原位x射线衍射/成像的潜在应用。
{"title":"Screening of TiB2-based ternary composites for X-ray transparent heaters in high-pressure and high-temperature experiments","authors":"Zhang Yu-tian, Guoliang Niu, Pengfei Tan, Chuanhui Zhu, Huiyang Gou, David Walker, Man‐Rong Li","doi":"10.1063/5.0275504","DOIUrl":"https://doi.org/10.1063/5.0275504","url":null,"abstract":"High-pressure and high-temperature (HPHT) experiments in large-volume presses (LVPs) benefit from reliable, available, and affordable heaters to achieve stable and homogeneous heating and, in some circumstances, X-ray transparency for monitoring of properties of an in situ experiment using X-ray diffraction and contrast imaging techniques. We have developed heaters meeting the above requirements, and we screen the ternary system TiB2–SiC–hexagonal (h)BN (denoted as TSB) to enable manufacture of X-ray transparent heaters for HPHT runs. Heaters fabricated using optimized TSB-631 (60%TiB2–30%SiC–10%hBN by weight) have been tested in modified truncated assemblies, showing excellent performance up to 22 GPa and 2395 K in HPHT runs. TSB-631 has good ceramic machinability, outstanding reproducibility, high stability, and negligible temperature gradient for runs at 3–7 GPa with cell assemblies with truncated edge lengths of 8–12 mm. The fabricated heaters not only show excellent performance in HPHT runs, but also demonstrate high X-ray transparency over a wide X-ray wavelength region, indicating potential applications for in situ X-ray diffraction/imaging under HPHT conditions in LVPs and other high-pressure apparatus.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"10 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147331480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xuesong Geng, Tongjun Xu, Lingang Zhang, Igor Kostyukov, Alexander Pukhov, Baifei Shen, Liangliang Ji
Laser wakefield acceleration (LWFA) promises compact accelerators toward the high-energy frontier. However, the approach to the 100 GeV milestone faces the obstacle of the long focal length required for optimal acceleration with high-power lasers, which reaches hundreds of meters for 10–100 PW lasers. The long focal length originates from optimal laser intensity required to avoid nonlinear effects and hence large spot size and Rayleigh length. We propose a “telescope” geometry in which a micro-plasma parabola (MPP) is coupled with a short-focal-length off-axis parabola, minimizing the focal length to the meter range for LWFA under optimized conditions driven by lasers beyond 1 PW. Full-dimensional kinetic simulations demonstrate the generation of a 9 GeV electron bunch within only 1 m optical length—only one-tenth of that required with the conventional approach with the same performance. The proposed MPP provides a basis for the construction of compact LWFAs toward single-stage 100 GeV acceleration with 100 PW class lasers.
{"title":"Compact laser wakefield acceleration toward high energy with micro-plasma parabola","authors":"Xuesong Geng, Tongjun Xu, Lingang Zhang, Igor Kostyukov, Alexander Pukhov, Baifei Shen, Liangliang Ji","doi":"10.1063/5.0202964","DOIUrl":"https://doi.org/10.1063/5.0202964","url":null,"abstract":"Laser wakefield acceleration (LWFA) promises compact accelerators toward the high-energy frontier. However, the approach to the 100 GeV milestone faces the obstacle of the long focal length required for optimal acceleration with high-power lasers, which reaches hundreds of meters for 10–100 PW lasers. The long focal length originates from optimal laser intensity required to avoid nonlinear effects and hence large spot size and Rayleigh length. We propose a “telescope” geometry in which a micro-plasma parabola (MPP) is coupled with a short-focal-length off-axis parabola, minimizing the focal length to the meter range for LWFA under optimized conditions driven by lasers beyond 1 PW. Full-dimensional kinetic simulations demonstrate the generation of a 9 GeV electron bunch within only 1 m optical length—only one-tenth of that required with the conventional approach with the same performance. The proposed MPP provides a basis for the construction of compact LWFAs toward single-stage 100 GeV acceleration with 100 PW class lasers.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"12 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142247678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hollow ion X-ray emission is of great interest in high-energy-density research, since negligible opacity allows studies from the interior of very dense objects. In this paper, ionization potential depressions of the isoelectronic sequences for single and double K-shell vacancies are obtained from a pure ab initio multiconfiguration Hartree–Fock simulation including exact exchange terms and finite temperature dense plasma effects. It is demonstrated that the simultaneous representation of these ab initio data in the form of a map of hollow ion X-ray transition energies enables identification of important steps in the matter evolution and ionization dynamics. Mapping along the isoelectronic sequence as a function of the pumping energy of a X-ray free electron laser also enables visualization of the impact of ionization potential depression on the pathways of hollow ion formation.
空心离子的 X 射线发射在高能量密度研究中具有重大意义，因为可以忽略的不透明性允许从非常致密的物体内部进行研究。本文从纯 ab initio 多配置 Hartree-Fock 模拟（包括精确交换项和有限温度致密等离子体效应）中获得了单 K 壳空位和双 K 壳空位等电子序列的电离势凹陷。结果表明，以空心离子 X 射线跃迁能量图的形式同时表示这些 ab initio 数据，能够识别物质演化和电离动力学的重要步骤。根据 X 射线自由电子激光器泵浦能量的函数绘制等电子序列图，还能使电离势抑对空心离子形成途径的影响可视化。
{"title":"Hollow ion atomic structure and X-ray emission in dense hot plasmas","authors":"Frank B. Rosmej, Christopher J. Fontes","doi":"10.1063/5.0226041","DOIUrl":"https://doi.org/10.1063/5.0226041","url":null,"abstract":"Hollow ion X-ray emission is of great interest in high-energy-density research, since negligible opacity allows studies from the interior of very dense objects. In this paper, ionization potential depressions of the isoelectronic sequences for single and double K-shell vacancies are obtained from a pure ab initio multiconfiguration Hartree–Fock simulation including exact exchange terms and finite temperature dense plasma effects. It is demonstrated that the simultaneous representation of these ab initio data in the form of a map of hollow ion X-ray transition energies enables identification of important steps in the matter evolution and ionization dynamics. Mapping along the isoelectronic sequence as a function of the pumping energy of a X-ray free electron laser also enables visualization of the impact of ionization potential depression on the pathways of hollow ion formation.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"58 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jun Kong, Kaiyuan Shi, Artem R. Oganov, Jiaqing Zhang, Lei Su, Xiao Dong
It is well known that atoms of the same element in different valence states show very different chemical behaviors. Calcium is a typical divalent metal, sharing or losing both of its valence electrons when forming compounds. Attempts have been made to synthesize compounds of monovalent calcium ions for decades, but with very little success (e.g., in clusters). Pressure can result in substantial changes in the properties of atoms and chemical bonding, creating an extensive variety of unique materials with special valence states. In this study, using the ab initio evolutionary algorithm USPEX, we search for stable calcium–chlorine (Ca–Cl) system compounds at pressures up to 100 GPa. Besides the expected compound CaCl2, we predict three new compounds with monovalent Ca to be stable at high pressures, namely, CaCl, Ca5Cl6, and Ca3Cl4. According to our calculations, CaCl is stable at pressures above 18 GPa and is predicted to undergo a transition from nonmagnetic Fm-3m-CaCl to ferromagnetic Pm-3m-CaCl at 40 GPa. Ca5Cl6 and Ca3Cl4 are stable at pressures above 37 and 73 GPa, with space groups P-1 and R-3, respectively. Following these predictions, we successfully synthesized Pm-3m-CaCl in laser-heated diamond anvil cell experiments. The emergence of the unusual valence state at high pressures reveals exciting opportunities for creating entirely new materials in sufficiently large quantities for a variety of potential applications.
{"title":"Exotic compounds of monovalent calcium synthesized at high pressure","authors":"Jun Kong, Kaiyuan Shi, Artem R. Oganov, Jiaqing Zhang, Lei Su, Xiao Dong","doi":"10.1063/5.0222230","DOIUrl":"https://doi.org/10.1063/5.0222230","url":null,"abstract":"It is well known that atoms of the same element in different valence states show very different chemical behaviors. Calcium is a typical divalent metal, sharing or losing both of its valence electrons when forming compounds. Attempts have been made to synthesize compounds of monovalent calcium ions for decades, but with very little success (e.g., in clusters). Pressure can result in substantial changes in the properties of atoms and chemical bonding, creating an extensive variety of unique materials with special valence states. In this study, using the ab initio evolutionary algorithm USPEX, we search for stable calcium–chlorine (Ca–Cl) system compounds at pressures up to 100 GPa. Besides the expected compound CaCl2, we predict three new compounds with monovalent Ca to be stable at high pressures, namely, CaCl, Ca5Cl6, and Ca3Cl4. According to our calculations, CaCl is stable at pressures above 18 GPa and is predicted to undergo a transition from nonmagnetic Fm-3m-CaCl to ferromagnetic Pm-3m-CaCl at 40 GPa. Ca5Cl6 and Ca3Cl4 are stable at pressures above 37 and 73 GPa, with space groups P-1 and R-3, respectively. Following these predictions, we successfully synthesized Pm-3m-CaCl in laser-heated diamond anvil cell experiments. The emergence of the unusual valence state at high pressures reveals exciting opportunities for creating entirely new materials in sufficiently large quantities for a variety of potential applications.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"27 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Brun, L. Ribotte, G. Boutoux, X. Davoine, P. E. Masson-Laborde, Y. Sentoku, N. Iwata, N. Blanchot, D. Batani, I. Lantuéjoul, L. Lecherbourg, B. Rosse, C. Rousseaux, B. Vauzour, D. Raffestin, E. D’Humières, X. Ribeyre
This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser (PETAL) laser. The experiments were performed during the commissioning of the laser. The laser had an energy of about 400 J, an intensity of 8 × 1018 W cm−2, and a pulse duration of 660 fs (FWHM). It was shot at a 2 mm-thick solid tungsten target. The high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the target. This paper reports measurements of electrons, protons and photons. Hot electrons up to ≈35 MeV with a few-MeV temperature were recorded by a spectrometer, called SESAME (Spectre ÉlectronS Angulaire Moyenne Énergie). K- and L-shells were clearly detected by a photon spectrometer called SPECTIX (Spectromètre Petal à Cristal en TransmIssion pour le rayonnnement X). High-energy photons were diagnosed by CRACC-X (Cassette de RAdiographie Centre Chambre-rayonnement X), a bremsstrahlung cannon. Bremsstrahlung cannon analysis is strongly dependent on the hypothesis adopted for the spectral shape. Different shapes can exhibit similar reproductions of the experimental data. To eliminate dependence on the shape hypothesis and to facilitate analysis of the data, simulations of the interaction were performed. To model the mechanisms involved, a simulation chain including hydrodynamic, particle-in-cell, and Monte Carlo simulations was used. The simulations model the preplasma generated at the front of the target by the PETAL laser prepulse, the acceleration of electrons inside the plasma, the generation of MeV-range photons from these electrons, and the response of the detector impacted by the energetic photon beam. All this work enabled reproduction of the experimental data. The high-energy photons produced have a large emission angle and an exponential distribution shape. In addition to the analysis of the photon spectra, positron production was also investigated. Indeed, if high-energy photons are generated inside the solid target, some positron/electron pairs may be produced by the Bethe–Heitler process. Therefore, the positron production achievable within the PETAL laser facility was quantified. To conclude the study, the possibility of creating electron/positron pairs through the linear Breit–Wheeler process with PETAL was investigated.
本文报告了利用高强度 PETawatt Aquitaine 激光器（PETAL）产生的高能光子的首次测量结果。实验是在激光器调试期间进行的。该激光器的能量约为 400 J，强度为 8 × 1018 W cm-2，脉冲持续时间为 660 fs (FWHM)。它被射向一个 2 毫米厚的实心钨靶。高能光子主要产生于在靶前侧产生的等离子体内加速的相对论电子的轫致辐射过程。本文报告了对电子、质子和光子的测量结果。名为 SESAME（Spectre ÉlectronS Angulaire Moyenne Énergie）的光谱仪记录了温度高达 ≈35 MeV 的热电子。名为 SPECTIX（Spectromètre Petal à Cristal en TransmIssion pour le rayonnnement X）的光子光谱仪清楚地探测到了 K 壳和 L 壳。高能光子由 CRACC-X（Cassette de RAdiographie Centre Chambre-rayonnement X）诊断，这是一种轫致辐射炮。轫致辐射加农炮分析在很大程度上取决于对光谱形状所采用的假设。不同形状的光谱可以重现类似的实验数据。为了消除对形状假设的依赖，并便于分析数据，我们对相互作用进行了模拟。为了模拟相关机制，我们使用了一个模拟链，其中包括流体力学模拟、粒子在细胞内模拟和蒙特卡罗模拟。模拟模拟了 PETAL 激光预脉冲在目标前部产生的预等离子体、等离子体内电子的加速、这些电子产生的 MeV 量级光子以及探测器对高能光子束的响应。所有这些工作都使实验数据得以重现。产生的高能光子具有较大的发射角和指数分布形状。除了分析光子光谱外，还研究了正电子的产生。事实上，如果高能光子在固体靶内产生，一些正电子/电子对可能会通过贝特-海特勒过程产生。因此，我们对 PETAL 激光设备可实现的正电子产生量进行了量化。在研究的最后，还研究了利用 PETAL 通过线性布雷特-惠勒过程产生电子/正电子对的可能性。
{"title":"Experimental measurements of gamma-photon production and estimation of electron/positron production on the PETAL laser facility","authors":"F. Brun, L. Ribotte, G. Boutoux, X. Davoine, P. E. Masson-Laborde, Y. Sentoku, N. Iwata, N. Blanchot, D. Batani, I. Lantuéjoul, L. Lecherbourg, B. Rosse, C. Rousseaux, B. Vauzour, D. Raffestin, E. D’Humières, X. Ribeyre","doi":"10.1063/5.0206416","DOIUrl":"https://doi.org/10.1063/5.0206416","url":null,"abstract":"This article reports the first measurements of high-energy photons produced with the high-intensity PETawatt Aquitaine Laser (PETAL) laser. The experiments were performed during the commissioning of the laser. The laser had an energy of about 400 J, an intensity of 8 × 1018 W cm−2, and a pulse duration of 660 fs (FWHM). It was shot at a 2 mm-thick solid tungsten target. The high-energy photons were produced mainly from the bremsstrahlung process for relativistic electrons accelerated inside a plasma generated on the front side of the target. This paper reports measurements of electrons, protons and photons. Hot electrons up to ≈35 MeV with a few-MeV temperature were recorded by a spectrometer, called SESAME (Spectre ÉlectronS Angulaire Moyenne Énergie). K- and L-shells were clearly detected by a photon spectrometer called SPECTIX (Spectromètre Petal à Cristal en TransmIssion pour le rayonnnement X). High-energy photons were diagnosed by CRACC-X (Cassette de RAdiographie Centre Chambre-rayonnement X), a bremsstrahlung cannon. Bremsstrahlung cannon analysis is strongly dependent on the hypothesis adopted for the spectral shape. Different shapes can exhibit similar reproductions of the experimental data. To eliminate dependence on the shape hypothesis and to facilitate analysis of the data, simulations of the interaction were performed. To model the mechanisms involved, a simulation chain including hydrodynamic, particle-in-cell, and Monte Carlo simulations was used. The simulations model the preplasma generated at the front of the target by the PETAL laser prepulse, the acceleration of electrons inside the plasma, the generation of MeV-range photons from these electrons, and the response of the detector impacted by the energetic photon beam. All this work enabled reproduction of the experimental data. The high-energy photons produced have a large emission angle and an exponential distribution shape. In addition to the analysis of the photon spectra, positron production was also investigated. Indeed, if high-energy photons are generated inside the solid target, some positron/electron pairs may be produced by the Bethe–Heitler process. Therefore, the positron production achievable within the PETAL laser facility was quantified. To conclude the study, the possibility of creating electron/positron pairs through the linear Breit–Wheeler process with PETAL was investigated.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"7 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study radiative transfer in participating binary stochastic mixtures in two dimensions (2D) by developing an accurate and efficient simulation tool. For two different sets of physical parameters, 2D benchmark results are presented, and it is found that the influence of the stochastic mixture on radiative transfer is clearly parameter-dependent. Our results confirm that previous multidimensional results obtained in different studies are basically consistent, which is interpreted in terms of the relationship between the photon mean free path lp and the system size L. Nonlinear effects, including those due to scattering and radiation–material coupling, are also discussed. To further understand the particle size effect, we employ a dimensionless parameter lp/L, from which a critical particle size can be derived. On the basis of further 2D simulations, we find that an inhomogeneous mix is obtained for lp/L > 0.1. Furthermore, 2D material temperature distributions reveal that self-shielding and particle–particle shielding of radiation occur, and are enhanced when lp/L is increased. Our work is expected to provide benchmark results to verify proposed homogenized models and/or other codes for stochastic radiative transfer in realistic physical scenarios.
{"title":"Benchmark simulations of radiative transfer in participating binary stochastic mixtures in two dimensions","authors":"Cong-Zhang Gao, Ying Cai, Cheng-Wu Huang, Yang Zhao, Jian-Wei Yin, Zheng-Feng Fan, Jia-Min Yang, Pei Wang, Shao-Ping Zhu","doi":"10.1063/5.0208236","DOIUrl":"https://doi.org/10.1063/5.0208236","url":null,"abstract":"We study radiative transfer in participating binary stochastic mixtures in two dimensions (2D) by developing an accurate and efficient simulation tool. For two different sets of physical parameters, 2D benchmark results are presented, and it is found that the influence of the stochastic mixture on radiative transfer is clearly parameter-dependent. Our results confirm that previous multidimensional results obtained in different studies are basically consistent, which is interpreted in terms of the relationship between the photon mean free path lp and the system size L. Nonlinear effects, including those due to scattering and radiation–material coupling, are also discussed. To further understand the particle size effect, we employ a dimensionless parameter lp/L, from which a critical particle size can be derived. On the basis of further 2D simulations, we find that an inhomogeneous mix is obtained for lp/L &gt; 0.1. Furthermore, 2D material temperature distributions reveal that self-shielding and particle–particle shielding of radiation occur, and are enhanced when lp/L is increased. Our work is expected to provide benchmark results to verify proposed homogenized models and/or other codes for stochastic radiative transfer in realistic physical scenarios.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"80 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The widely used quasi-isentropic ramp loading technique relies heavily on back-calculation methods that convert the measured free-surface velocity profiles to the stress–density states inside the compressed sample. Existing back-calculation methods are based on one-dimensional isentropic hydrodynamic equations, which assume a well-defined functional relationship P(ρ) between the longitudinal stress and density throughout the entire flow field. However, this kind of idealized stress–density relation does not hold in general, because of the complexities introduced by structural phase transitions and/or elastic–plastic response. How and to what extent these standard back-calculation methods may be affected by such inherent complexities is still an unsettled question. Here, we present a close examination using large-scale molecular dynamics (MD) simulations that include the detailed physics of the irreversibly compressed solid samples. We back-calculate the stress–density relation from the MD-simulated rear surface velocity profiles and compare it directly against the stress–density trajectories measured from the MD simulation itself. Deviations exist in the cases studied here, and these turn out to be related to the irreversibility between compression and release. Rarefaction and compression waves are observed to propagate with different sound velocities in some parts of the flow field, violating the basic assumption of isentropic hydrodynamic models and thus leading to systematic back-calculation errors. In particular, the step-like feature of the P(ρ) curve corresponding to phase transition may be completely missed owing to these errors. This kind of mismatch between inherent properties of matter and the basic assumptions of isentropic hydrodynamics has a fundamental influence on how the ramp loading method can be applied.
{"title":"Fundamental influence of irreversible stress–strain properties in solids on the validity of the ramp loading method","authors":"Jingxiang Shen, Wei Kang","doi":"10.1063/5.0210797","DOIUrl":"https://doi.org/10.1063/5.0210797","url":null,"abstract":"The widely used quasi-isentropic ramp loading technique relies heavily on back-calculation methods that convert the measured free-surface velocity profiles to the stress–density states inside the compressed sample. Existing back-calculation methods are based on one-dimensional isentropic hydrodynamic equations, which assume a well-defined functional relationship P(ρ) between the longitudinal stress and density throughout the entire flow field. However, this kind of idealized stress–density relation does not hold in general, because of the complexities introduced by structural phase transitions and/or elastic–plastic response. How and to what extent these standard back-calculation methods may be affected by such inherent complexities is still an unsettled question. Here, we present a close examination using large-scale molecular dynamics (MD) simulations that include the detailed physics of the irreversibly compressed solid samples. We back-calculate the stress–density relation from the MD-simulated rear surface velocity profiles and compare it directly against the stress–density trajectories measured from the MD simulation itself. Deviations exist in the cases studied here, and these turn out to be related to the irreversibility between compression and release. Rarefaction and compression waves are observed to propagate with different sound velocities in some parts of the flow field, violating the basic assumption of isentropic hydrodynamic models and thus leading to systematic back-calculation errors. In particular, the step-like feature of the P(ρ) curve corresponding to phase transition may be completely missed owing to these errors. This kind of mismatch between inherent properties of matter and the basic assumptions of isentropic hydrodynamics has a fundamental influence on how the ramp loading method can be applied.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"5 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. L. C. Lacoste, A. Hirsch, E. d’Humières, V. T. Tikhonchuk, P. Antici, M. Bardon
An analytical model of current propagation in a helical coil with varying geometry is developed. It can be used for post-acceleration and post-focusing of ions produced via laser-driven target normal sheath acceleration and generation of electromagnetic pulses. We calculate the current that propagates in a helical coil and suggest a method for improving its dispersion properties using a screening tube and with pitch and radius variation. The electromagnetic fields calculated with the analytical model are in agreement with particle-in-cell simulations. The model provides insights into the physics of current propagation in helical coils with varying geometries and enables a numerical implementation for rapid proton spectrum computations, which facilitate the design of such coils for future experiments.
{"title":"Theoretical model of current propagation in a helical coil with varying geometry and screen tube","authors":"C. L. C. Lacoste, A. Hirsch, E. d’Humières, V. T. Tikhonchuk, P. Antici, M. Bardon","doi":"10.1063/5.0221820","DOIUrl":"https://doi.org/10.1063/5.0221820","url":null,"abstract":"An analytical model of current propagation in a helical coil with varying geometry is developed. It can be used for post-acceleration and post-focusing of ions produced via laser-driven target normal sheath acceleration and generation of electromagnetic pulses. We calculate the current that propagates in a helical coil and suggest a method for improving its dispersion properties using a screening tube and with pitch and radius variation. The electromagnetic fields calculated with the analytical model are in agreement with particle-in-cell simulations. The model provides insights into the physics of current propagation in helical coils with varying geometries and enables a numerical implementation for rapid proton spectrum computations, which facilitate the design of such coils for future experiments.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"3 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142186524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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