In traditional high-pressure–temperature assembly design, priority has been given to temperature insulation and retention at high pressures. This limits the efficiency of cooling of samples at the end of experiments, with a negative impact on many studies in high-pressure Earth and planetary science. Inefficient cooling of experiments containing molten phases at high temperature leads to the formation of quench textures, which makes it impossible to quantify key compositional parameters of the original molten phase, such as their volatile contents. Here, we present a new low-cost experimental assembly for rapid cooling in a six-anvil cubic press. This assembly not only retains high heating efficiency and thermal insulation, but also enables a very high cooling rate (∼600 °C/s from 1900 °C to the glass transition temperature). Without using expensive materials or external modification of the press, the cooling rate in an assembly (∼600 °C/s) with cube lengths of 38.5 mm is about ten times faster than that in the traditional assembly (∼60 °C/s). Experiments yielding inhomogeneous quenched melt textures when the traditional assembly is used are shown to yield homogeneous silicate glass without quench textures when the rapid cooling assembly is used.
在传统的高压高温组件设计中，优先考虑的是高压下的温度绝缘和保持。这限制了实验结束时冷却样品的效率，对高压地球和行星科学的许多研究产生了负面影响。在高温下对含有熔融相的实验进行低效冷却会形成淬火纹理，从而无法量化原始熔融相的关键成分参数，如挥发物含量。在此，我们介绍一种新型低成本实验组件，用于在六安立方压力机中快速冷却。该装置不仅保持了较高的加热效率和隔热性能，还实现了极高的冷却速度（从 1900 °C 到玻璃化转变温度的冷却速度为 600 °C/s）。在不使用昂贵材料或对压机进行外部改装的情况下，立方体长度为 38.5 毫米的组件冷却速度（∼600 °C/s）比传统组件（∼60 °C/s）快约十倍。实验表明，使用传统装配时会产生不均匀的淬火熔体纹理，而使用快速冷却装配时则会产生均匀的硅酸盐玻璃，且不会产生淬火纹理。
{"title":"A novel rapid cooling assembly design in a high-pressure cubic press apparatus","authors":"Peiyan Wu, Yongjiang Xu, Yanhao Lin","doi":"10.1063/5.0176025","DOIUrl":"https://doi.org/10.1063/5.0176025","url":null,"abstract":"In traditional high-pressure–temperature assembly design, priority has been given to temperature insulation and retention at high pressures. This limits the efficiency of cooling of samples at the end of experiments, with a negative impact on many studies in high-pressure Earth and planetary science. Inefficient cooling of experiments containing molten phases at high temperature leads to the formation of quench textures, which makes it impossible to quantify key compositional parameters of the original molten phase, such as their volatile contents. Here, we present a new low-cost experimental assembly for rapid cooling in a six-anvil cubic press. This assembly not only retains high heating efficiency and thermal insulation, but also enables a very high cooling rate (∼600 °C/s from 1900 °C to the glass transition temperature). Without using expensive materials or external modification of the press, the cooling rate in an assembly (∼600 °C/s) with cube lengths of 38.5 mm is about ten times faster than that in the traditional assembly (∼60 °C/s). Experiments yielding inhomogeneous quenched melt textures when the traditional assembly is used are shown to yield homogeneous silicate glass without quench textures when the rapid cooling assembly is used.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"47 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139981291","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}
Dong Wang, Ningning Wang, Caoshun Zhang, Chunsheng Xia, Weicheng Guo, Xia Yin, Kejun Bu, Takeshi Nakagawa, Jianbo Zhang, Federico Gorelli, Philip Dalladay-Simpson, Thomas Meier, Xujie Lü, Liling Sun, Jinguang Cheng, Qiaoshi Zeng, Yang Ding, Ho-kwang Mao
Following the recent report by Dasenbrock-Gammon et al. [Nature 615, 244–250 (2023)] of near-ambient superconductivity in nitrogen-doped lutetium trihydride (LuH3−δNε), significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance drop. Here, we meticulously revisit these claims through comprehensive characterization and investigations. We definitively identify the reported material as lutetium dihydride (LuH2), resolving the ambiguity surrounding its composition. Under similar conditions (270–295 K and 1–2 GPa), we replicate the reported sharp decrease in electrical resistance with a 30% success rate, aligning with the observations by Dasenbrock-Gammon et al. However, our extensive investigations reveal this phenomenon to be a novel pressure-induced metal-to-metal transition intrinsic to LuH2, distinct from superconductivity. Intriguingly, nitrogen doping exerts minimal impact on this transition. Our work not only elucidates the fundamental properties of LuH2 and LuH3, but also critically challenges the notion of superconductivity in these lutetium hydride systems. These findings pave the way for future research on lutetium hydride systems, while emphasizing the crucial importance of rigorous verification in claims of ambient-temperature superconductivity.
{"title":"Unveiling a novel metal-to-metal transition in LuH2: Critically challenging superconductivity claims in lutetium hydrides","authors":"Dong Wang, Ningning Wang, Caoshun Zhang, Chunsheng Xia, Weicheng Guo, Xia Yin, Kejun Bu, Takeshi Nakagawa, Jianbo Zhang, Federico Gorelli, Philip Dalladay-Simpson, Thomas Meier, Xujie Lü, Liling Sun, Jinguang Cheng, Qiaoshi Zeng, Yang Ding, Ho-kwang Mao","doi":"10.1063/5.0183701","DOIUrl":"https://doi.org/10.1063/5.0183701","url":null,"abstract":"Following the recent report by Dasenbrock-Gammon et al. [Nature 615, 244–250 (2023)] of near-ambient superconductivity in nitrogen-doped lutetium trihydride (LuH3−δNε), significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance drop. Here, we meticulously revisit these claims through comprehensive characterization and investigations. We definitively identify the reported material as lutetium dihydride (LuH2), resolving the ambiguity surrounding its composition. Under similar conditions (270–295 K and 1–2 GPa), we replicate the reported sharp decrease in electrical resistance with a 30% success rate, aligning with the observations by Dasenbrock-Gammon et al. However, our extensive investigations reveal this phenomenon to be a novel pressure-induced metal-to-metal transition intrinsic to LuH2, distinct from superconductivity. Intriguingly, nitrogen doping exerts minimal impact on this transition. Our work not only elucidates the fundamental properties of LuH2 and LuH3, but also critically challenges the notion of superconductivity in these lutetium hydride systems. These findings pave the way for future research on lutetium hydride systems, while emphasizing the crucial importance of rigorous verification in claims of ambient-temperature superconductivity.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"33 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948430","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 propose an efficient scheme to produce ultrahigh-brightness tens of MeV electron beams by designing a density-tailored plasma to induce a wakefield in the weakly nonlinear regime with a moderate laser energy of 120 mJ. In this scheme, the second bucket of the wakefield can have a much lower phase velocity at the steep plasma density down-ramp than the first bucket and can be exploited to implement longitudinal electron injection at a lower laser intensity, leading to the generation of bright electron beams with ultralow emittance together with low energy spread. Three-dimensional particle-in-cell simulations are carried out and demonstrate that high-quality electron beams with a peak energy of 50 MeV, ultralow emittance of ∼28 nm rad, energy spread of 1%, charge of 4.4 pC, and short duration less than 5 fs can be obtained within a 1-mm-long tailored plasma density, resulting in an ultrahigh six-dimensional brightness B6D,n of ∼2 × 1017 A/m2/0.1%. By changing the density parameters, tunable bright electron beams with peak energies ranging from 5 to 70 MeV, a small emittance of ≤0.1 mm mrad, and a low energy spread at a few-percent level can be obtained. These bright MeV-class electron beams have a variety of potential applications, for example, as ultrafast electron probes for diffraction and imaging, in laboratory astrophysics, in coherent radiation source generation, and as injectors for GeV particle accelerators.
{"title":"Ultrahigh-brightness 50 MeV electron beam generation from laser wakefield acceleration in a weakly nonlinear regime","authors":"Zhongtao Xiang, Changhai Yu, Zhiyong Qin, Xuhui Jiao, Jiahui Cheng, Qiaoxuan Zhou, Gatie Axi, Jianghua Jie, Ya Huang, Jintan Cai, Jiansheng Liu","doi":"10.1063/5.0189460","DOIUrl":"https://doi.org/10.1063/5.0189460","url":null,"abstract":"We propose an efficient scheme to produce ultrahigh-brightness tens of MeV electron beams by designing a density-tailored plasma to induce a wakefield in the weakly nonlinear regime with a moderate laser energy of 120 mJ. In this scheme, the second bucket of the wakefield can have a much lower phase velocity at the steep plasma density down-ramp than the first bucket and can be exploited to implement longitudinal electron injection at a lower laser intensity, leading to the generation of bright electron beams with ultralow emittance together with low energy spread. Three-dimensional particle-in-cell simulations are carried out and demonstrate that high-quality electron beams with a peak energy of 50 MeV, ultralow emittance of ∼28 nm rad, energy spread of 1%, charge of 4.4 pC, and short duration less than 5 fs can be obtained within a 1-mm-long tailored plasma density, resulting in an ultrahigh six-dimensional brightness B6D,n of ∼2 × 1017 A/m2/0.1%. By changing the density parameters, tunable bright electron beams with peak energies ranging from 5 to 70 MeV, a small emittance of ≤0.1 mm mrad, and a low energy spread at a few-percent level can be obtained. These bright MeV-class electron beams have a variety of potential applications, for example, as ultrafast electron probes for diffraction and imaging, in laboratory astrophysics, in coherent radiation source generation, and as injectors for GeV particle accelerators.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"205 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948739","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}
Y. X. Wang, X. L. Zhu, S. M. Weng, P. Li, X. F. Li, H. Ai, H. R. Pan, Z. M. Sheng
The generation of ultrashort high-power light sources in the mid-infrared (mid-IR) to terahertz (THz) range is of interest for applications in a number of fields, from fundamental research to biology and medicine. Besides conventional laser technology, photon deceleration in plasma wakes provides an alternative approach to the generation of ultrashort mid-IR or THz pulses. Here, we present a photon deceleration scheme for the efficient generation of ultrashort mid-IR or THz pulses by using an intense driver laser pulse with a relatively short wavelength and a signal laser pulse with a relatively long wavelength. The signal pulse trails the driver pulse with an appropriate time delay such that it sits at the front of the second wake bubble that is driven by the driver pulse. Owing to its relatively long wavelength, the signal pulse will be subjected to a large gradient of the refractive index in the plasma wake bubble. Consequently, the photon deceleration in the plasma wake becomes faster and more efficient for signal pulses with longer wavelengths. This greatly enhances the capacity and efficiency of photon deceleration in the generation of ultrashort high-power light sources in the long-wavelength IR and THz spectral ranges.
{"title":"Fast efficient photon deceleration in plasmas by using two laser pulses at different frequencies","authors":"Y. X. Wang, X. L. Zhu, S. M. Weng, P. Li, X. F. Li, H. Ai, H. R. Pan, Z. M. Sheng","doi":"10.1063/5.0189638","DOIUrl":"https://doi.org/10.1063/5.0189638","url":null,"abstract":"The generation of ultrashort high-power light sources in the mid-infrared (mid-IR) to terahertz (THz) range is of interest for applications in a number of fields, from fundamental research to biology and medicine. Besides conventional laser technology, photon deceleration in plasma wakes provides an alternative approach to the generation of ultrashort mid-IR or THz pulses. Here, we present a photon deceleration scheme for the efficient generation of ultrashort mid-IR or THz pulses by using an intense driver laser pulse with a relatively short wavelength and a signal laser pulse with a relatively long wavelength. The signal pulse trails the driver pulse with an appropriate time delay such that it sits at the front of the second wake bubble that is driven by the driver pulse. Owing to its relatively long wavelength, the signal pulse will be subjected to a large gradient of the refractive index in the plasma wake bubble. Consequently, the photon deceleration in the plasma wake becomes faster and more efficient for signal pulses with longer wavelengths. This greatly enhances the capacity and efficiency of photon deceleration in the generation of ultrashort high-power light sources in the long-wavelength IR and THz spectral ranges.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"31 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948429","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}
Coherent motion of particles in a plasma can imprint itself on radiation. The recent advent of high-power lasers—allowing the nonlinear inverse Compton-scattering regime to be reached—has opened the possibility of looking at collective effects in laser–plasma interactions. Under certain conditions, the collective interaction of many electrons with a laser pulse can generate coherent radiation in the hard x-ray regime. This perspective paper explains the limitations under which such a regime might be attained.
等离子体中粒子的相干运动会对辐射产生影响。最近出现的大功率激光器可以达到非线性反康普顿散射机制，这为研究激光与等离子体相互作用中的集体效应提供了可能。在某些条件下，许多电子与激光脉冲的集体相互作用可以产生硬 X 射线系统中的相干辐射。这篇视角论文解释了在何种限制条件下可以达到这种机制。
{"title":"Collective coherent emission of electrons in strong laser fields and perspective for hard x-ray lasers","authors":"E. G. Gelfer, A. M. Fedotov, O. Klimo, S. Weber","doi":"10.1063/5.0174508","DOIUrl":"https://doi.org/10.1063/5.0174508","url":null,"abstract":"Coherent motion of particles in a plasma can imprint itself on radiation. The recent advent of high-power lasers—allowing the nonlinear inverse Compton-scattering regime to be reached—has opened the possibility of looking at collective effects in laser–plasma interactions. Under certain conditions, the collective interaction of many electrons with a laser pulse can generate coherent radiation in the hard x-ray regime. This perspective paper explains the limitations under which such a regime might be attained.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"31 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139767435","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}
Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one of the youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to the Moon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertite was found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunar samples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compression during a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stages of an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition for coexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca8Y)□Fe2+(PO4)7 (where □ denotes a vacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form of columnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching up to ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combined with silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials and the special nature of lunar magmatic evolution.
{"title":"High-pressure minerals and new lunar mineral changesite-(Y) in Chang’e-5 regolith","authors":"Jing Yang, Wei Du","doi":"10.1063/5.0148784","DOIUrl":"https://doi.org/10.1063/5.0148784","url":null,"abstract":"Forty-five years after the Apollo and Luna missions, China’s Chang’e-5 (CE-5) mission collected ∼1.73 kg of new lunar materials from one of the youngest basalt units on the Moon. The CE-5 lunar samples provide opportunities to address some key scientific questions related to the Moon, including the discovery of high-pressure silica polymorphs (seifertite and stishovite) and a new lunar mineral, changesite-(Y). Seifertite was found to be coexist with stishovite in a silica fragment from CE-5 lunar regolith. This is the first confirmed seifertite in returned lunar samples. Seifertite has two space group symmetries (Pnc2 and Pbcn) and formed from an α-cristobalite-like phase during “cold” compression during a shock event. The aftershock heating process changes some seifertite to stishovite. Thus, this silica fragment records different stages of an impact process, and the peak shock pressure is estimated to be ∼11 to 40 GPa, which is much lower than the pressure condition for coexistence of seifertite and stishovite on the phase diagram. Changesite-(Y), with ideal formula (Ca8Y)□Fe2+(PO4)7 (where □ denotes a vacancy) is the first new lunar mineral to be discovered in CE-5 regolith samples. This newly identified phosphate mineral is in the form of columnar crystals and was found in CE-5 basalt fragments. It contains high concentrations of Y and rare earth elements (REE), reaching up to ∼14 wt. % (Y,REE)2O3. The occurrence of changesite-(Y) marks the late-stage fractional crystallization processes of CE-5 basalts combined with silicate liquid immiscibility. These new findings demonstrate the significance of studies on high-pressure minerals in lunar materials and the special nature of lunar magmatic evolution.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"91 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139768094","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}
J. Cikhardt, M. Gyrdymov, S. Zähter, P. Tavana, M. M. Günther, N. Bukharskii, N. Borisenko, J. Jacoby, X. F. Shen, A. Pukhov, N. E. Andreev, O. N. Rosmej
Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the process of direct laser acceleration (DLA) of electrons in a relativistic laser channel when the electrons undergo transverse betatron oscillations in self-generated quasi-static electric and magnetic fields. In an experiment at the PHELIX laser system, high-current directed beams of DLA electrons with a mean energy ten times higher than the ponderomotive potential and maximum energy up to 100 MeV were measured at 1019 W/cm2 laser intensity. The spectrum of directed x-rays in the range of 5–60 keV was evaluated using two sets of Ross filters placed at 0° and 10° to the laser pulse propagation axis. The differential x-ray absorption method allowed for absolute measurements of the angular-dependent photon fluence. We report 1013 photons/sr with energies >5 keV measured at 0° to the laser axis and a brilliance of 1021 photons s−1 mm−2 mrad−2 (0.1%BW)−1. The angular distribution of the emission has an FWHM of 14°–16°. Thanks to the ultra-high photon fluence, point-like radiation source, and ultra-short emission time, DLA-based keV backlighters are promising for various applications in high-energy-density research with kilojoule petawatt-class laser facilities.
研究了中等相对论强度的亚皮秒激光脉冲与近临界密度等离子体相互作用时产生的定向 X 射线。在相对论激光通道中的电子直接激光加速（DLA）过程中，当电子在自生的准静态电场和磁场中发生横向贝塔射线振荡时，会产生类似同步加速器（贝塔射线）的辐射。在 PHELIX 激光系统的一次实验中，以 1019 W/cm2 的激光强度测量到了大电流定向 DLA 电子束，其平均能量是深思动势的十倍，最大能量高达 100 MeV。使用与激光脉冲传播轴成 0° 和 10° 的两组罗斯滤波器，对 5-60 keV 范围内的定向 X 射线光谱进行了评估。利用差分 X 射线吸收法可以绝对测量随角度变化的光子通量。我们的报告显示，在与激光轴线成 0°的位置测量到的光子数量为 1013 个/sr，能量为 >5 keV，亮度为 1021 光子 s-1 mm-2 mrad-2（0.1%BW）-1。发射角分布的全宽均方根（FWHM）为 14°-16°。由于具有超高光子通量、点状辐射源和超短发射时间，基于 DLA 的 keV 背光源有望在千焦耳石油瓦级激光设备的高能量密度研究中得到广泛应用。
{"title":"Characterization of bright betatron radiation generated by direct laser acceleration of electrons in plasma of near critical density","authors":"J. Cikhardt, M. Gyrdymov, S. Zähter, P. Tavana, M. M. Günther, N. Bukharskii, N. Borisenko, J. Jacoby, X. F. Shen, A. Pukhov, N. E. Andreev, O. N. Rosmej","doi":"10.1063/5.0181119","DOIUrl":"https://doi.org/10.1063/5.0181119","url":null,"abstract":"Directed x-rays produced in the interaction of sub-picosecond laser pulses of moderate relativistic intensity with plasma of near-critical density are investigated. Synchrotron-like (betatron) radiation occurs in the process of direct laser acceleration (DLA) of electrons in a relativistic laser channel when the electrons undergo transverse betatron oscillations in self-generated quasi-static electric and magnetic fields. In an experiment at the PHELIX laser system, high-current directed beams of DLA electrons with a mean energy ten times higher than the ponderomotive potential and maximum energy up to 100 MeV were measured at 1019 W/cm2 laser intensity. The spectrum of directed x-rays in the range of 5–60 keV was evaluated using two sets of Ross filters placed at 0° and 10° to the laser pulse propagation axis. The differential x-ray absorption method allowed for absolute measurements of the angular-dependent photon fluence. We report 1013 photons/sr with energies >5 keV measured at 0° to the laser axis and a brilliance of 1021 photons s−1 mm−2 mrad−2 (0.1%BW)−1. The angular distribution of the emission has an FWHM of 14°–16°. Thanks to the ultra-high photon fluence, point-like radiation source, and ultra-short emission time, DLA-based keV backlighters are promising for various applications in high-energy-density research with kilojoule petawatt-class laser facilities.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"308 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139767978","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}
Kaiguo Chen, Bo Chen, Yinan Cui, Yuying Yu, Jidong Yu, Huayun Geng, Dongdong Kang, Jianhua Wu, Yao Shen, Jiayu Dai
Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extreme conditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50 is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physical properties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change are successfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relatively insensitive to the strain rate γ̇ when γ̇ ranges from 7.5 × 108 to 2 × 109/s, which are values reachable in QIC experiments, with a magnitude of the order of 10−2kB/atom per GPa. However, when γ̇ is extremely high (>2×109/s), a notable increase in entropy production rate with γ̇ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated that entropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase in configurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamental relation between microstructure evolution and plastic dissipation.
{"title":"On the thermodynamics of plasticity during quasi-isentropic compression of metallic glass","authors":"Kaiguo Chen, Bo Chen, Yinan Cui, Yuying Yu, Jidong Yu, Huayun Geng, Dongdong Kang, Jianhua Wu, Yao Shen, Jiayu Dai","doi":"10.1063/5.0176138","DOIUrl":"https://doi.org/10.1063/5.0176138","url":null,"abstract":"Entropy production in quasi-isentropic compression (QIC) is critically important for understanding the properties of materials under extreme conditions. However, the origin and accurate quantification of entropy in this situation remain long-standing challenges. In this work, a framework is established for the quantification of entropy production and partition, and their relation to microstructural change in QIC. Cu50Zr50 is taken as a model material, and its compression is simulated by molecular dynamics. On the basis of atomistic simulation-informed physical properties and free energy, the thermodynamic path is recovered, and the entropy production and its relation to microstructural change are successfully quantified by the proposed framework. Contrary to intuition, entropy production during QIC of metallic glasses is relatively insensitive to the strain rate γ̇ when γ̇ ranges from 7.5 × 108 to 2 × 109/s, which are values reachable in QIC experiments, with a magnitude of the order of 10−2kB/atom per GPa. However, when γ̇ is extremely high (>2×109/s), a notable increase in entropy production rate with γ̇ is observed. The Taylor–Quinney factor is found to vary with strain but not with strain rate in the simulated regime. It is demonstrated that entropy production is dominated by the configurational part, compared with the vibrational part. In the rate-insensitive regime, the increase in configurational entropy exhibits a linear relation to the Shannon-entropic quantification of microstructural change, and a stretched exponential relation to the Taylor–Quinney factor. The quantification of entropy is expected to provide thermodynamic insights into the fundamental relation between microstructure evolution and plastic dissipation.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"93 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139773517","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 present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Cone-inserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on the point-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peak compression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metal microwire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamic simulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, areal densities of the targets were evaluated.
我们介绍了短脉冲激光产生的硬 X 射线在间接驱动双壳目标诊断中的应用。在升级版 SG-II 激光设备上，通过间接驱动方法对锥形插入式双壳目标进行了内爆。然后，基于点投影硬 X 射线射线照相技术，获得了双壳靶的时间分辨射线照相，包括其近峰值压缩的射线照相。背光源是由高强度短脉冲激光与金属微线靶相互作用产生的。使用金微线获得了目标接近峰值压缩的图像。此外，还进行了辐射流体力学模拟，得到的目标演变与实验结果非常吻合。利用射线图像，对目标的面积密度进行了评估。
{"title":"Diagnosis of indirectly driven double shell targets with point-projection hard x-ray radiography","authors":"Chao Tian, Minghai Yu, Lianqiang Shan, Fengjuan Wu, Bi Bi, Qiangqiang Zhang, Yuchi Wu, Tiankui Zhang, Feng Zhang, Dongxiao Liu, Weiwu Wang, Zongqiang Yuan, Siqian Yang, Lei Yang, Zhigang Deng, Jian Teng, Weimin Zhou, Zongqing Zhao, Yuqiu Gu, Baohan Zhang","doi":"10.1063/5.0045112","DOIUrl":"https://doi.org/10.1063/5.0045112","url":null,"abstract":"We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Cone-inserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on the point-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peak compression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metal microwire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamic simulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, areal densities of the targets were evaluated.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"11 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139500950","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}
Tao Chen, Qianrui Liu, Yu Liu, Liang Sun, Mohan Chen
In traditional finite-temperature Kohn–Sham density functional theory (KSDFT), the partial occupation of a large number of high-energy KS eigenstates restricts the use of first-principles molecular dynamics methods at extremely high temperatures. However, stochastic density functional theory (SDFT) can overcome this limitation. Recently, SDFT and the related mixed stochastic–deterministic density functional theory, based on a plane-wave basis set, have been implemented in the first-principles electronic structure software ABACUS [Q. Liu and M. Chen, Phys. Rev. B 106, 125132 (2022)]. In this study, we combine SDFT with the Born–Oppenheimer molecular dynamics method to investigate systems with temperatures ranging from a few tens of eV to 1000 eV. Importantly, we train machine-learning-based interatomic models using the SDFT data and employ these deep potential models to simulate large-scale systems with long trajectories. Subsequently, we compute and analyze the structural properties, dynamic properties, and transport coefficients of warm dense matter.
在传统的有限温度 Kohn-Sham 密度泛函理论（KSDFT）中，大量高能 KS 特征态的部分占据限制了第一原理分子动力学方法在极高温下的使用。然而，随机密度泛函理论（SDFT）可以克服这一限制。最近，基于平面波基集的 SDFT 和相关的随机-确定混合密度泛函理论已在第一原理电子结构软件 ABACUS 中实现 [Q. Liu and M. Chen, Phys. Rev. B 106, 125132 (2022)]。在本研究中，我们将 SDFT 与 Born-Oppenheimer 分子动力学方法结合起来，研究温度范围从几十 eV 到 1000 eV 的系统。重要的是，我们利用 SDFT 数据训练基于机器学习的原子间模型，并利用这些深度势能模型模拟具有长轨迹的大规模系统。随后，我们计算并分析了温致密物质的结构特性、动态特性和传输系数。
{"title":"Combining stochastic density functional theory with deep potential molecular dynamics to study warm dense matter","authors":"Tao Chen, Qianrui Liu, Yu Liu, Liang Sun, Mohan Chen","doi":"10.1063/5.0163303","DOIUrl":"https://doi.org/10.1063/5.0163303","url":null,"abstract":"In traditional finite-temperature Kohn–Sham density functional theory (KSDFT), the partial occupation of a large number of high-energy KS eigenstates restricts the use of first-principles molecular dynamics methods at extremely high temperatures. However, stochastic density functional theory (SDFT) can overcome this limitation. Recently, SDFT and the related mixed stochastic–deterministic density functional theory, based on a plane-wave basis set, have been implemented in the first-principles electronic structure software ABACUS [Q. Liu and M. Chen, Phys. Rev. B 106, 125132 (2022)]. In this study, we combine SDFT with the Born–Oppenheimer molecular dynamics method to investigate systems with temperatures ranging from a few tens of eV to 1000 eV. Importantly, we train machine-learning-based interatomic models using the SDFT data and employ these deep potential models to simulate large-scale systems with long trajectories. Subsequently, we compute and analyze the structural properties, dynamic properties, and transport coefficients of warm dense matter.","PeriodicalId":54221,"journal":{"name":"Matter and Radiation at Extremes","volume":"9 1","pages":""},"PeriodicalIF":5.1,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139412091","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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