P2 is the remaining principal asymmetry in laser-driven hohlraums. A simple analytic model for P2 asymmetry on the Shenguang 100 kJ laser facility is presented, which is based on hohlraum geometry, wall albedo, plasma expansion, and shell velocity. The calculated P2 asymmetry from the model is in reasonably good agreement with experimental data from pre-pulse, shell flight and stagnation stages. The P2 model appears to capture the essential physics governing drive symmetry and has been implemented to guide new symmetric implosion designs, enabling a more rapid convergence to a symmetric implosion than the conventional trial-and-error approach.

Pyrochlore ceramics possess low thermal conductivity, good electrical transport, and high thermal stability, making them promising for low-infrared-emissivity applications. However, their microstructural evolution and infrared emissivity behavior during atmospheric plasma spraying (APS) remain unclear. In this work, Y2Ti2O7 powders were synthesized via solid-state reaction and deposited as coatings using APS. The effects of spraying power and heat treatment on phase composition, microstructure, and infrared emissivity were systematically investigated. APS-induced rapid cooling led to partial decomposition of Y2Ti2O7 into Y2TiO5 and TiO2, with volatilization of TiO2 and formation of a pyrochlore-fluorite dual-phase structure. Post-spray heat treatment promoted recrystallization into stable pyrochlore, while Ti-deficient regions yielded Y0.63Ti0.37O1.67. Porosity and lattice distortion enhanced phonon scattering and free carrier absorption, contributing to reduced emissivity. These findings offer insights into the processing-structure-property relationship of APS-fabricated pyrochlore coatings for high-temperature infrared stealth applications.

Collective Thomson scattering (CTS) is crucial for inertial confinement fusion (ICF) hohlraum diagnostics, but measurement of the electron plasma wave (EPW) feature remains challenging. The conventional collisionless model suffers from two critical defects: under low-temperature, high-density conditions it predicts an extremely narrow EPW peak that causes numerical sampling distortion, and it predicts a monotonic increase of peak intensity with decreasing scattering angle, which would mislead experimental design. To overcome these issues, the Bhatnagar–Gross–Krook (BGK) collisional model is introduced. The BGK model predicts a nonmonotonic peak intensity with an optimal angle between 30° and 60°, and yields a finite, resolvable peak width that eliminates sampling artifacts. It also enables reliable assessment of drive-beam backgrounds. Guided by the predicted optimal angle, CTS experiments at 42° were performed on the Shenguang-100 kJ facility. For the first time, both ion and electron features were simultaneously measured in the hohlraum corona, with the electron signal clearly distinguishable from the background. Joint fitting provides the temporal evolution of electron density and temperature. This work establishes a unified, collision-corrected diagnostic framework that overcomes a long-standing obstacle to measuring electron density and temperature in ICF hohlraum plasmas.

Detailed investigation of the x-ray drive on the capsule at the center of the hohlraum is crucial to solve the "drive deficit" problem in inertial confinement fusion. A pioneering work for probing the drive flux at the hohlraum center by simultaneously measuring the re-emitted flux and shock velocity was reported [X. Xie et al., Phys. Rev. Lett. 128, 075001 (2022)0031-900710.1103/PhysRevLett.128.075001]. However, in the last experiment only two discrete shock velocity values can be obtained, as the streaked optical pyrometer was employed. In this work, we present characterization of the time-dependent x-ray drive on the capsule by simultaneously measuring the time-dependent localized re-emitted flux and the time-dependent shock velocity. The time-dependent localized re-emitted flux was measured by the space-resolving flux detector, while the time-dependent shock velocity was obtained with the velocity interferometer system for any reflector. Two-dimensional radiation hydrodynamic simulations revealed that the time history of the re-emitted flux as well as the shock velocity can be well reproduced. This technique presented a way for the determination of the x-ray drive at the center of the cylindrical hohlraum as well as other novel hohlraums.

Abstract The technique of indirect-drive cryogenic pure deuterium layered implosion is unique among published works in the research of inertial confinement fusion. After its feasibility was demonstrated recently, we proceeded to improve the implosion performance by using a 2-shock shaped pulse. The target design was evolved from an ignition target design with modifications compatible with current energy scale. The radiation uniformity was confirmed by the dual-axis keyhole targets and cryogenic gas-filled targets. The adiabat of the fuel was controlled by tuning shocks to emerge at the ice-gas interface. The implosion performance of the layered targets were then investigated. The pure deuterium layers of good quality were maintained for a few minutes. The lasers were fired during the survival time of such layer quality. The resulting neutron yield was 9.6×1010, and the hotspot pressure was 30Gbar. Radiative hydrodynamic simulations were carried out using as-shot target and laser parameters, and compared with the experimental measurements. The yield of clean was about 19%. The residual radiation non-uniformity alone cannot explain the observed performance degradation. The hydrodynamic instabilities seeded by ice roughness should play a role in decreasing the hotspot clean volume.

Precise prediction of the hohlraum x-ray drive is essential for target design optimization in indirect-drive inertial confinement fusion. Conventional simulations, however, are often hampered by the hohlraum drive deficit, which limits their predictive power for new experimental configurations. This study focuses on the two-shock implosions of the 100 kJ-level laser facility, aiming to infer the radiation source constrained by multiple diagnostics. A joint inversion method for the radiation source and M -band x-ray power multipliers was developed, leading to the construction of a surrogate model that maps experimental design parameters to radiation source waveforms. Based on this model, a deep learning inference framework, PRISM, was established to achieve precise radiation source prediction. The model exhibits excellent predictive accuracy, and the bang-time prediction error in pre-shot simulations is reduced from about 500 ps to within 200 ps. Its extrapolation capability was validated using transmission grating spectrometer data, demonstrating good agreement between simulated and measured spectra. Shapley Additive Explanations revealed the relative contributions of experimental design parameters to each multiplier. Finally, we used residual-based analysis to quantify engineering accuracy. The analysis indicates improved engineering control of the 100 kJ-level laser facility in 2025, particularly in laser output stability, although pulse synchronization remain areas for refinement.

In indirect-drive inertial confinement fusion (ICF), the radiation drive temperature of the hohlraum is related to the shock velocity and implosion velocity of the capsule. The radiation drive symmetry on the capsule is the vital parameter for the hotspot symmetry. A new method is proposed to simultaneously determine the radiation temperature and P2 asymmetry on the capsule by measuring the re-emitted x-ray radiation flux along two orthogonal directions. The interaction between the hohlraum and the imploded capsule can be decoupled by employing a high-Z substitute capsule. The effects of opacity and equation of state on the measurement of the P2 asymmetry are given based on the self-similarity theory. The demonstration experiments were conducted on the Shenguang-100 kJ laser facility. The evolutions of the radiation drive temperature and P2 asymmetry are obtained in the experiment. The impact of diagnostic holes and laser beam absences on the P2 asymmetry is quantitatively evaluated with the view-factor calculation. The temporal trend of the symmetry is consistent between the experiment and the integrated simulation (LARED-JC). However, the experimental symmetry differs from the simulation results from the middle of the main pulse. This might be caused by the inverse bremsstrahlung absorption or the crossed-beam energy transfer (CBET) process. The new method can provide both radiation drive temperature and P2 asymmetry for different hohlraumsin experiments. It enables time-resolved determination of both the laser power multiplier and the cone fraction multiplier, which is beneficial for optimizing the innovative hohlraum designs.

To meet the need for ultrathin high-temperature radar-stealth coatings with effective X-band absorption, a metasurface-regulated FeSiCr/CaO-B2O3-SiO2 (FSC/CBS) composite coating was designed. FSC/CBS coatings with different FSC contents were fabricated by atmospheric plasma spraying to examine the effects of absorber loading on particle state, microstructure, electromagnetic parameters, and high-temperature absorption. Increasing FSC content raised the in-flight particle temperature and promoted FSC spreading and flattening, causing the absorbing phase to evolve from isolated particles to lamellar structures and locally connected conductive networks. These structural features enhanced interfacial polarization and conduction loss, whereas excessive FSC aggregation suppressed the effective magnetic response through demagnetization and skin-effect shielding, degrading impedance matching. The 1-mm-thick 40FSC/CBS coating showed stable Ku-band absorption at 600 °C, with reflection loss below -5 dB over 11.7-18.0 GHz. After metasurface loading, its effective absorption band was regulated to 8.0-13.78 GHz, covering the entire X band, and the cavity radar cross section was reduced by 12.17 dBsm.

Backscattering due to laser plasma instabilities (LPIs) presents a risk in the laser-driven inertial confinement fusion. Generally, it is assumed that the backscattering of laser beams in the same cone is identical in hohlraum physics studies. In the experiments performed at SG-100kJ laser facility, we find that the backscattering of laser beams in the same cone are quite different. Our investigation reveals the main reason for this phenomenon is that the laser beams in the same cone obtain different power from their neighbor beams via crossed-beam energy transfer (CBET) depending on their polarizations. The dependence of multi-beam CBET on laser polarization arrangement is confirmed in a specially designed experiment. These findings are crucial for understanding the backscattering, CBET, energy deficit and the azimuthal drive asymmetry in cylindrical hohlraums.

The influence of unwanted X-ray background as well as the variation of the physical condition for radiation temperature (Tr) measurement is investigated in this work. Laser clipping by LEH, residual unconverted light striking target support structures and laser energy deposited on the CH membranes will lead to an overestimation of the hohlraum Tr. Laser pointing accuracy and laser power imbalance change the fraction of certain laser spots as well as their energy in the sight of view, causing a deviation in estimating the hohlraum Tr. Besides, LEH closure will lead to an underestimation of the hohlraum Tr.

Early hot electron can preheat the pellet fuel and thus lead to lower implosion performance. The properties of hot electrons in early stage of implosion experiments in Shenguang-100 kJ laser facility were investigated. It was shown that both the temperature and the energy of early hot electrons were very low. The upper limit of the temperature and the energy of early hot electrons in our experiments were only 7.7 keV and 0.35 J, respectively. Besides, the generation mechanisms of early hot electrons were also different from NIF experiments according to the results of the hard X-ray imager (HXI). In NIF experiments, two-plasmon decay and multi-beam stimulated Raman scattering (SRS) were dominate mechanisms that generate early hot electrons. However, SRS of the outer beams was our dominant mechanism. Spectrum of the scattered light of SRS was obtained by radiative hydrodynamic and ray-tracing simulations. The result showed that the spectrum was peaked at λ _s=482 nm , which meant hot electrons with the temperature near 7keV can be generated. And from the result of HXI, hot electrons deposited onto the pellet were estimated to less than 6.8× 10^-3 J. Deeper analysis showed that, in the beam overlapping region, the plasma density was unsuitable for multi-beam SRS, so no hot electrons with larger temperature were generated.

An experiment on 100 kJ laser facility is performed to study the motive features and radiation properties of plasmas from different areas inside gas-filled cylindrical hohlraums. These hohlraums are designed to possess one open end and one laser entrance hole (LEH) with different diameters, which would or not result in the blocking of the LEH. An x-ray streak camera that is set at 16 degrees with respect to the hohlraum axis is applied to acquire the time-resolved x-ray images from the open end. Based on the images, we can study the evolutions of the wall plasma, corona bubble plasma and LEH plasma simultaneously through an equivalent view field of hohlraum interior. Multi-group flat response x-ray detectors are applied to measure the x-ray fluxes. In order to understand these characteristics, our two-dimensional radiation hydrodynamic code is used to simulate the experimental results. For the accuracy of reproduction, dielectronic recombination and two parameter corrections are applied in our code. Based on the comparison between experiments and simulations, we quantitatively understand the blocking process of LEH and the motion effects of other plasmas. The calibrated code is beneficial to design the gas-filled hohlraum in a nearby parameter space, especially the limit size of LEH.

In an experiment performed on the Shenguang-III prototype laser facility, collective Thomson scattering (TS) is used to study the spatial growth of stimulated Brillouin scattering (SBS) in a gas-filled hohlraum by detecting the SBS-driven ion acoustic wave. High-quality time-resolved SBS and TS spectra are obtained simultaneously in the experiment, and these are analyzed by a steady-state code based on the ray-tracing model. The analysis indicates that ion–ion collisions may play an important role in suppressing SBS growth in the Au plasma; as a result, the SBS excited in the filled gas region is dominant. In the early phase of the laser pulse, SBS originates primarily from the high-density plasma at the edges of the interaction beam channel, which is piled up by the heating of the interaction beam. Throughout the duration of the laser pulse, the presence of the TS probe beam might mitigate SBS by perturbing the density distribution around the region overlapping with the interaction beam.

The tubular gas-liquid atomization mixer can atomize the liquid absorbent into micron-level droplets in a limited tubular space to achieve efficient gas-liquid mixing,thereby significantly increasing the gas-liquid contact area and enhancing the gas-liquid absorption and mass transfer process.It is the key equipment for the transformation of natural gas glycol dehydration technology from tower type to tubular type.In order to improve the liquid jet breaking and gas-liquid dispersion and mixing performance in the tubular gas-liquid atomization mixer,based on the initial flow channel structure,three different improved flow channel structures were proposed.Combining experimental testing and numerical simulation methods,the influence of the flow channel structure on the atomization and mixing performance of the tubular gas-liquid atomization mixer was explored,and a more reasonable flow channel structure was screened out by comparison.The study found that the atomization pressure drop increases with the increase of gas flow rate,and slightly decreases with the increase of gas-liquid ratio.The particle size of atomized droplets gradually decreases with the increase of gas flow rate and gas-liquid ratio.Under the same working conditions,the droplet size of the diamond-shaped cone with a boss structure is the smallest,and the particle size distribution is concentrated at 37-60 μm,which is more than 40% smaller than the particle size of the initial flow channel structure; and the atomized droplet concentration of the structure is the highest,which is 5-17 times higher than the volume concentration of the initial flow channel structure.The reason is that the diamond-shaped cone structure helps to guide the uniform flow of the lateral airflow,effectively reduces wall adhesion,and plays the role of enhancing droplet breakage and reducing the thickness of the liquid film; the boss structure helps to enhance the gas-liquid dispersion effect,reduce the average droplet size and increases the concentration of atomized droplets.

Based on the experimental conditions of the Shenguang-100 kJ laser facility, the feasibility and applicability of the deep ultraviolet quintuple-frequency Thomson scattering diagnostics are evaluated, and compared with the widely used quadruple-frequency Thomson scattering, so as to provide a reference for the technical route for high-precision diagnosis of inertial confinement fusion plasmas. The probe beam signal, the drive-beam background, and the bremsstrahlung background are evaluated, and the measurement bands of the Thomson scattering ion spectrum and electron spectrum are discussed respectively. The results show that for the ion spectrum, the signal to-background ratio can be significantly improved by using a quintuple-frequency probe beam. For the red peak of the electron spectrum, whether a quintuple-frequency probe beam or a quadruple-frequency probe beam is used, it is strongly disturbed by the intense background of the drive beam. For the blue peak of the electron spectrum, the drive beam background can be avoided by using a quintuple-frequency probe beam, while the bremsstrahlung background will be significantly enhanced. In general, quintuple-frequency Thomson scattering has significant advantages in the measurement of low atomic number plasmas, but not for high atomic number plasmas.

在神光Ⅲ原型装置上，利用8束三倍频（351.0 nm）激光注入充气黑腔产生大尺度高温等离子体并激发高水平受激布里渊散射（SBS）过程。利用1束四倍频（263.3 nm）探针束和1套广角汤姆逊散射诊断系统，获得了三倍频激光SBS过程驱动的离子声波的超热相干汤姆逊散射（STS）光谱。通过对STS光谱和背向SBS光谱进行联合分析，揭示了SBS的时空演化过程。

In this paper, we propose and demonstrate a novel, to the best of knowledge, filter-free photonics-assisted microwave frequency translator with a tunable phase shift and amplitude. The pivotal component of the proposed scheme is an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator, which is applied to generate a polarization orthogonal carrier-suppressed single sideband modulation signal and frequency shifted optical carrier signal. The polarization-multiplexed optical signal outputs from the DP-QPSK modulator is then sent to a photodetector (PD) via a polarization controller (PC) and a polarizer to implement photoelectric conversion. The electrical signal output from the PD is the desired frequency translated microwave signal, and the amount of frequency shift is determined by the frequency of the sawtooth wave applied to the DP-QPSK modulator. In addition, since the PC can be used to adjust the polarization angle and introduce a phase difference between the two orthogonally polarized optical signals, the phase shift and amplitude of the obtained translated signal can also be easily tuned. A theoretical analysis and simulation experiment are carried out to verify the feasibility of the proposed scheme. The simulation results show that the novel scheme can realize frequency translation with a 360° continuously tunable phase shift and adjustable amplitude for both a single-tone signal and linearly frequency modulated signal with a 50 MHz bandwidth. The spurious suppression ratios of the single-tone signal and LFM signal after frequency translation are larger than 48 and 30 dB, respectively.

In indirect-drive hohlraum, the heated plasmas from the laser entrance hole (LEH) and bubbles blow radially inward with time, which plays an important role in the evolution of hohlraum plasmas. Previously, the boundary of the LEH and bubble plasmas is measured using time-integrated x-ray images or x-ray images at several discrete moments. A new experiment is conducted to study the continuous temporal behaviors of the LEH and bubble plasmas, which utilizes a gas-filled hohlraum truncated on one side. Compared experiments are performed with 3 different LEH diameters (1.0 mm, 1.2 mm, and 1.4 mm) An x-ray streak camera (XSC) is employed for the first time to diagnose the continuous temporal x-ray images of the LEH and bubble plasmas, which are also measured by an x-ray framing camera (XFC) at several discrete moments. The XSC and the XFC are combined for the first time and give coincident results for the movement of the LEH and bubble plasmas. In addition, 2 sets of flat-response x-ray diode (FXRD) measure the total x-ray flux from both the LEH and the open end and thus give the radiation temperature (Tr) in the hohlraum. The Tr from the LEH end shows a visual increase compared with that from the open end, due to the LEH closure, which is coincident with the temporal x-ray images. This work presents more precise and detailed description for the continuous movement of the LEH and bubble plasmas, which is beneficial to optimize our radiation hydrodynamic code and hohlraum design for ignition.

In indirect-drive hohlraum, the heated plasmas from the laser entrance hole (LEH) and bubbles blow radially inward with time, which plays an important role in the evolution of hohlraum plasmas. Previously, the boundary of the LEH and bubble plasmas is measured using time-integrated x-ray images or x-ray images at several discrete moments. A new experiment is conducted to study the continuous temporal behaviors of the LEH and bubble plasmas, which utilizes a gas-filled hohlraum truncated on one side. Compared experiments are performed with 3 different LEH diameters (1.0 mm, 1.2 mm, and 1.4 mm). An x-ray streak camera (XSC) is employed for the first time to diagnose the continuous temporal x-ray images of the LEH and bubble plasmas, which are also measured by an x-ray framing camera (XFC) at several discrete moments. The XSC and the XFC are combined for the first time and give coincident results for the movement of the LEH and bubble plasmas. In addition, 2 sets of flat-response x-ray diode (FXRD) measure the total x-ray flux from both the LEH and the open end and thus give the radiation temperature (Tr) in the hohlraum. The Tr from the LEH end shows a visual increase compared with that from the open end, due to the LEH closure, which is coincident with the temporal x-ray images. This work presents more precise and detailed description for the continuous movement of the LEH and bubble plasmas, which is beneficial to optimize our radiation hydrodynamic code and hohlraum design for ignition.