Matter and Radiation at Extremes

Progress in shock wave diagnostic technology based on velocity interferometers for laser inertial confinement fusion

Wang Feng, Li Yulong, Guan Zanyang, Peng Xiaoshi, Liu Xiangming, Yang Dong, Yang Jiamin, Zhao Zongqing

2026, 11(2) doi: 10.1063/5.0249311

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Abstract:
Laser-driven inertial confinement fusion (ICF) is an important experimental platform for high-energy-density physics research under extreme conditions. In ICF research, high-quality shock waves are key to fusion energy release. The velocity interferometer system for any reflector (VISAR) is the most important diagnostic technique for measuring quantities such as shock wave and particle velocities with high precision and high spatiotemporal resolution. This paper provides a detailed introduction to the various configurations of VISAR on 10 and 100 kJ-level laser facilities in China, including Line VISAR, Dual-Axis VISAR, Wide-Angle VISAR, and Compressed Ultrafast Photography-VISAR. Recent advances and applications of VISAR diagnostics at these laser facilities are presented, and the future trend of development of high-spatiotemporal-resolution velocity diagnostic technology is described.

Ab initio density functional theory approach to warm dense hydrogen: From density response to electronic correlations

Moldabekov Zhandos A., Shao Xuecheng, Bellenbaum Hannah M., Ma Cheng, Mi Wenhui, Schwalbe Sebastian, Vorberger Jan, Dornheim Tobias

2026, 11(2) doi: 10.1063/5.0297301

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Abstract:
Understanding the properties of warm dense hydrogen is of key importance for the modeling of compact astrophysical objects and to understand and further optimize inertial confinement fusion applications. The workhorse of warm dense matter theory is thermal density functional theory (DFT), which, however, suffers from two limitations: (i) its accuracy can depend on the utilized exchange–correlation functional, which has to be approximated, and (ii) it is generally limited to single-electron properties such as the density distribution. Here, we present a new ansatz combining time-dependent DFT results for the dynamic structure factor S_ee( q , ω) with static DFT results for the density response. This allows us to estimate the electron–electron static structure factor S_ee( q ) of warm dense hydrogen with high accuracy over a broad range of densities and temperatures. In addition to its value for the study of warm dense matter, our work opens up new avenues for the future study of electronic correlations exclusively within the framework of DFT for a host of applications.

Impact pressure shaping plasma jets and affected by high metallicity

Ma Zuolin, Ping Yongli, Zhong Jiayong

2026, 11(2) doi: 10.1063/5.0275550

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Abstract:
High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts. In this work, we revisit the framework of magnetohydrodynamic (MHD) theory and introduce a new analytical approach for examining plasma jets generated by intense laser–plasma interactions. Specifically, we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution. Furthermore, MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets. In addition, a pronounced dependence on the atomic number is identified: higher-Z materials amplify the impact pressure, suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.

Effect of intense radiation on the X-ray emission spectrum of non-LTE plasmas

Huang Chengwu, Zhu Tuo, Zhang Yuxue, Song Tianming, Zhao Yang, Zhang Jiyan, Zhang Zhiyu, Xiong Gang, Qing Bo, Zhao Yan, Li Liling, Wei Minxi, Wu Zeqing, Yan Jun, Yang Jiamin

2026, 11(2) doi: 10.1063/5.0304724

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Abstract:
Low-density non–local-thermodynamic-equilibrium plasmas in intense radiation fields occur widely in inertial confinement fusion and astrophysics. Understanding the X-ray spectrum and the atomic kinetics of such plasmas is therefore of great importance. However, the creation of uniform-density nonequilibrium plasmas in intense radiation fields in the laboratory and the measurement of their spectra with high resolution are challenging tasks. Here, we present a new method to produce such a uniform aluminum plasma and explore photon-induced kinetics and relevant atomic physics by measuring its spectrum. It is observed that in the presence of an external radiation field, the satellites q, r and a–d of the He-α resonance line are greatly enhanced compared with the satellites j, k, l. Analysis of atomic kinetics reveals that this effect of intense radiation is due to competition between the photoexcitation and autoionization processes. With this effect taken into account, simulated spectra are able to reproduce the measured spectra quite well.

Generation of extremely high-intensity tightly focused laser pulse via microstructured plasma target

Wang Jingyi, Zhang Lingyu, Zhang Hao, Chen Zhidong, Liu Ke, Li Xinyan, Hu Lixiang, Yu Tongpu

2026, 11(2) doi: 10.1063/5.0292697

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Abstract:
Plasma-based optical elements can withstand laser intensities several orders of magnitude higher than traditional optical elements, making them highly promising for manipulating relativistic intensity laser pulses. In this work, we propose and demonstrate a novel microstructured plasma target, inspired by the design of traditional Fresnel zone plates. The specific target structure causes diffraction of the input laser at each zone, resulting in constructive interference and facilitating effective focusing of the input laser pulse. Three-dimensional particle-in-cell simulation results show that the microstructured plasma target can focus Gaussian laser pulses with an intensity of the order of 10²² W/cm² to an intensity exceeding 10²⁴ W/cm² with the laser focus spot size approaching the diffraction limit of ∼0.73 μm and laser fluence enhancement by a factor of 46. It is also found that when the microstructured plasma target is modified into a reflective element, laser intensities up to 10²⁵ W/cm² may be achieved. This extremely high-intensity tightly focused laser pulse can trigger intense photon radiation when interacting with targets, (e.g., wire plasma targets), with potential applications in laboratory astrophysics, as well as providing the opportunity to explore phenomena such as vacuum birefringence and quantum electrodynamical cascades.

Tracking the complete evolution of electromagnetic instability in an ultra-intense laser-driven plasma

Shaikh Moniruzzaman, Lad Amit D., Mandal Devshree, Jana Kamalesh, Sarkar Deep, Das Amita, Kumar G. Ravindra

2026, 11(2) doi: 10.1063/5.0285819

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Abstract:
Plasmas, the most common state of matter in the observable universe, are subject to instabilities of various types: hydrodynamic, magnetohydrodynamic, and electromagnetic. Our limited success in understanding these is due to the lack of direct experimental information on their origins and evolution. Here, we present direct spatially resolved measurements of the femtosecond evolution of the electromagnetic beam-driven instability that arises from the interaction of forward and return currents in an ultrahigh-intensity laser-produced plasma. We track its evolution from the initial linear stage to the later nonlinear stage by measuring the spatiotemporal evolution of the giant (megagauss) magnetic field created in the interaction process. Our experimental findings and numerical simulations are the first to indicate the observed instability triggered by the emission of electromagnetic radiation, like those known in the context of gravitational interaction, where the emission of gravitational radiation drives specific negative-energy modes in rotating black holes or neutron stars.

Experimental and simulation study on high-power laser irradiation of 3D-printed microstructures

Cipriani M., Consoli F., Scisció M., Solovjovas A., Petsi I. A., Malinauskas M., Andreoli P., Cristofari G., Di Ferdinando E., Di Giorgio G.

2026, 11(2) doi: 10.1063/5.0283201

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Abstract:
Inertial confinement fusion (ICF) requires a constant search for the most effective materials to improve the efficiency of compression of the capsule and of laser-to-target energy transfer. Foams could provide a solution, but they require further experimental and theoretical investigation. The new 3D-printing technologies, such as two-photon polymerization, are opening a new era in the production of foams, allowing fine control of material morphology. Very few detailed studies of the interaction of foams with high-power lasers in regimes relevant for ICF have been described in the literature to date, and more investigation is needed. In this work, we present the results of an experimental campaign performed at the ABC laser facility at ENEA Centro Ricerche Frascati in which 3D-printed microstructured materials were irradiated at high power. 3D simulations of the laser–target interaction performed with the FLASH code reveal that the laser is scattered by plasma density gradients and channeled into the structure when the center of the focal spot is on the through hole. The time required for the laser to completely ablate the structure given by the simulations is in good agreement with the experimental measurement. Measurements of the reflected and transmitted laser light indicate that scattering occurred during the irradiation, in accordance with the simulations. Two-plasmon decay has also been found to be active during irradiation.

Asymmetric ion acceleration in laser-produced magnetized collisionless shocks

Zhang Tianyi, Guo Ao, Tang Huibo, Hu Guangyue, Huang Kai, Shao Shuoting, Yang Shunyi, Xie Jiayin, Peng Gaoyuan, E Peng, Lu Quanming

2026, 11(2) doi: 10.1063/5.0284676

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Abstract:
Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laser-produced supersonic plasma flow and a magnetized ambient plasma, exhibiting an angular asymmetric shock profile accompanied by asymmetric ion acceleration. We have conducted test particle simulations using the electromagnetic fields derived from 2D MHD simulations to investigate the asymmetry of ion acceleration. The simulations reproduce the angular asymmetry of the shock and the ion acceleration observed in experiments. The results indicate that shock drift acceleration is the primary mechanism for ion energization in the present quasi-perpendicular magnetized shock. The asymmetric shock structure caused by nonuniform ambient plasma forms an asymmetric accelerated electric field, ultimately leading to angular asymmetric ion acceleration, which is consistent with space observations and our experimental results. Our study provides a plausible explanation for the discrepancies reported in previous ion acceleration experiments, and could contribute to understanding of the collisionless shock acceleration.

3D radiation-hydrodynamics simulations of octahedral spherical hohlraums

Ramis Rafael

2026, 11(2) doi: 10.1063/5.0291101

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Abstract:
Achieving uniform X-ray irradiation in indirect-drive inertial confinement fusion (ICF) is a key challenge for successful capsule implosion. Spherical hohlraums, particularly those with octahedral laser entrance holes (LEHs), are an alternative to the cylindrical hohlraums currently considered for ICF at NIF (USA) and LMJ (France). These spherical hohlraums are advantageous in terms of irradiation uniformity on the fusion capsule because, owing to their octahedral symmetry, low-order asymmetries cancel out intrinsically. However, they may be less favorable from an energetic point of view, primarily owing to radiation losses through their multiple LEHs. The net balance of these advantages and disadvantages is difficult to determine, because, unlike cylindrical hohlraums, they require fully 3D modeling. To address this, a new version of the MULTI-3D simulation code has been developed. MULTI-3D is a 3D radiation-hydrodynamics code with arbitrary Langrangian–Eulerian (ALE) hydrodynamics, multigroup S_N radiation transport, and ray-tracing laser deposition. Using this tool, several aspects of the behavior of spherical hohlraums have been analyzed, with special attention to phenomena inaccessible to 2D modeling. In these targets, laser beams strike the inner walls at very oblique angles, and the expansion of plasma significantly alters the locations where primary X rays are produced. Furthermore, the complex distribution of laser hot spots leads to mutual interactions, where plasma bubbles from one beam intersect the path of another. The laser-to-X-ray energy conversion efficiency has been analyzed as a function of key parameters. The symmetry on the capsule has also been evaluated, revealing nonuniformities of less than 1%.

Hexagonal B–C–N composite consisting of h-BN and graphite separated by B–C nanolayer

Xu Baoyin, Yuan Xiaohong, Feng Bingtao, Jiang Yifeng, She Yaqi, Ding Zhanhui, Pan Yue, Liu Shucheng, Hu Kuo, Liu Zhaodong, Li Quanjun, Liu Bingbing, Tang Hu

2026, 11(2) doi: 10.1063/5.0302494

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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.

Pressure-induced high-energy-density and superhard Be–C–O compounds

Zhu Jinming, Bao Kuo, Wang Zhaoqing, Qin Yuan, Yu Hongyu, Cui Tian

2026, 11(2) doi: 10.1063/5.0301255

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Abstract:
Light element compounds under high pressure display intriguing properties and applications, owing to their diverse bonding patterns and crystalline structures. However, the system of ternary Be–C–O compounds under high pressure, as the lightest representative of the IIA–IVA–VIA family, remains largely unexplored. Using a machine-learning-accelerated crystal structure search and first-principles calculations, Be–C–O phase diagrams are investigated at pressures ranging from 0 to 100 GPa. Four ternary compounds are proposed to be stable at corresponding pressures: BeCO₃, Be₂CO₄, Be₂C₄O₃, and BeC₄O₂. Analyses of electronic structure and chemical bonding further reveal how the structural diversity of these compounds is induced. Remarkably, Be₂C₄O₃ and BeC₄O₂ are recoverable to ambient conditions and possess both high energy density and high hardness. The volumetric energy densities of Be₂C₄O₃ and BeC₄O₂ could approach 9.03 and 7.94 kJ/cm³, respectively. The Vickers hardnesses of Be₂C₄O₃ and BeC₄O₂ are found to be close to 39.58 and 51.57 GPa, respectively. These findings demonstrate the structural and functional diversity of Be–C–O compounds under high pressure, providing guidance for further exploration of the IIA–IVA–VIA compounds.

Current Issue
2026 Vol. 11, No. 2

Current Issue

Current Issue 2026 Vol. 11, No. 2

Current Issue

Current Issue
2026 Vol. 11, No. 2