The influence of homogenization parameters on element segregation,dendritic structure,and the precipitate evolution in the GH3535-0.08wt%Y alloy was investigated.Additionally,some specific homogenization parameters we...The influence of homogenization parameters on element segregation,dendritic structure,and the precipitate evolution in the GH3535-0.08wt%Y alloy was investigated.Additionally,some specific homogenization parameters were maintained constant throughout the experiments.Results indicate that the heat treatment at 1150℃for 10 h is the optimal homogenization condition.Following this optimal treatment,dendrite structures and element segregation are eliminated.Furthermore,both SiC and Y_(5)Si_(3)precipitates in the as-cast alloy decrease significantly.Conversely,the homogenization at 1188℃induces overheating defects within the alloy.Although SiC and Y_(5)Si_(3)phases also decrease,some large M6C phases can still be observed,adversely affecting subsequent forging processes.展开更多
The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,an...The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.展开更多
Experiments with interacting high-velocity flows in a laser plasma can help answer fundamental questions in plasma physics and improve understanding of the mechanisms behind some astrophysical phenomena,such as the fo...Experiments with interacting high-velocity flows in a laser plasma can help answer fundamental questions in plasma physics and improve understanding of the mechanisms behind some astrophysical phenomena,such as the formation of collisionless shock waves,deceleration of accretion flows,and evolution of solar and stellar flares.This work presents the first direct experimental observations of stagnation and redirection of counterstreaming flows(jets)of laser plasma induced by intense laser pulses with intensity I~2×10^(18) W/cm^(2).Hybrid particlein-cell-fluid modeling,which takes into account the kinetic effects of ion motion and the evolution of the pressure tensor for electrons,demonstrates the compression of counterdirected toroidal self-generated magnetic fields embedded in counterstreaming plasma flows.The enhancement of the toroidal magnetic field in the interaction region results in plasma flow stagnation and redirection of the jets across the line of their initial propagation.展开更多
At high count rates,pile-up events involving neutron and gamma signals result in inaccurate neutron counting and distortions in the energy spectrum.Additionally,a bipolar cusp-like pulse shaping algorithm based on an ...At high count rates,pile-up events involving neutron and gamma signals result in inaccurate neutron counting and distortions in the energy spectrum.Additionally,a bipolar cusp-like pulse shaping algorithm based on an unfolding synthesis technique was proposed.This algorithm exhibits a narrow pulse shape,and the parallel design of the dual algorithms enables the recovery of pile-up signal amplitudes while preserving the distinct characteristics of neutron and gamma signals.The simplicity of the algorithm facilitates real-time neutron/gamma discrimination on an FPGA,allowing the energy spectra to be updated with each incoming signal.Furthermore,the algorithm can be readily tailored to various experimental conditions by adjusting the decay time constants.Multi-objective optimization reduces the need for manual parameter tuning by rapidly identifying the optimal parameters.Testing with a^(241)Am-Be neutron source and a NaIL scintillator yielded a figure of merit(FoM)value of 2.11 and produced a clear energy spectrum even at high count rates.展开更多
The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases,resulting in a heterogeneous microstructural distribution that influences its performance.In this study,the rare earth yttria(Y_(2)O_(...The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases,resulting in a heterogeneous microstructural distribution that influences its performance.In this study,the rare earth yttria(Y_(2)O_(3))was employed to modify laser-clad Fe45 alloy coatings,and the effects of Y_(2)O_(3) addition on their microstructure,microhardness,and tribological properties were investigated.As the Y_(2)O_(3) content increases from 0%to 0.3wt.%,the dominant microstructure transforms from columnar crystals to fine cellular and equiaxed crystals.The modified coating with 0.3wt.%Y_(2)O_(3) achieves a surface hardness of 568 HV_(0.3)and a wear volume of 1,735.41 um~3,representing a 14.06%increase in hardness and a 51.16%reduction in wear volume compared to the undoped coating.Further increasing the Y_(2)O_(3) content from 0.3wt.%to 0.9wt.%gradually leads to the emergence of a coarser feather-like microstructure,characterized by a dendritic framework with inter-dendritic equiaxed crystals.Concurrently,both the hardness and wear resistance of the coating decrease.Nevertheless,all Y_(2)O_(3)-modified coatings surpass the undoped Fe45 coating in both hardness and wear resistance.Appropriate Y_(2)O_(3) doping effectively refines the Fe45 alloy coating's microstru cture and induces lattice distortion,thereby enhancing its hardness and wear resistance.展开更多
Knowing the precise relationship between fuel loading and reactivity is essential for guiding reactor criticality extrapolation and online refueling in molten salt reactors(MSRs).This study aims to explore and explain...Knowing the precise relationship between fuel loading and reactivity is essential for guiding reactor criticality extrapolation and online refueling in molten salt reactors(MSRs).This study aims to explore and explain the linear relationship between reactivity and the reciprocal of uranium concentration in thermal-spectrum MSRs.By applying neutron balance theory,we analyzed the neutron absorption cross sections of various nuclides in single-lattice models with varying fuel concentrations.Our findings reveal a simple linear correlation between reactivity and the reciprocal of uranium concentration,which can be explained from the perspective of nuclear reaction cross sections that adhere to the 1/v law in the thermal neutron spectrum.Furthermore,we identified that the neutron absorption single-group cross sections of structural materials and carrier salts exhibit an approximately linear relationship with the fission single-group cross section of ^(235) U;similarly,the reciprocal of ^(235)U’s fission cross section exhibits an approximately linear relationship with uranium concentration.This linear relationship deviates as the volume fraction of molten salt increases,due to a greater proportion of neutrons being captured in the resonance energy spectrum.However,it remains valid for molten salt volume fractions up to 25%and demonstrates broad applicability in the physical design and operation of thermal molten salt reactors.展开更多
The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation...The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation of Ti-containing inclusions,enhancing heterogeneous nucleation and promoting equiaxed dendritic growth in 347H stainless steel.Thermal simulation experiments indicated that the equiaxed crystal ratios increased notably with Ti content;samples with 0.06,0.12,and 0.36 wt.%Ti exhibited equiaxed ratios of 18%,24%,and 41%,respectively.Three primary inclusion types—TiN,Al_(2)O_(3)-TiN,and TiO_(x)-TiN—were identified at the cores of equiaxed dendrites,with nucleation core sizes predominantly ranging from 0.5 to 8μm.Among the tested samples,the 0.36 wt.%Ti addition produced the highest nucleation core density.Increasing Ti content significantly elevated dendrite tip undercooling from 2.6 K(0.06 wt.%Ti)to 10.8 K(0.36 wt.%Ti),accelerating solidification front instability and thus enhancing heterogeneous nucleation.Additionally,higher Ti content increased the divergence angle between adjacent columnar dendrites,further promoting the columnar-to-equiaxed transition(CET).展开更多
Based on the generalized reduced R-matrix theory,the R-matrix analysis code(RAC program)was used to analyze the experimental data of all the nuclear reaction channels related to the 5 He system.The current calculation...Based on the generalized reduced R-matrix theory,the R-matrix analysis code(RAC program)was used to analyze the experimental data of all the nuclear reaction channels related to the 5 He system.The current calculations provide accurate and reliable evaluation data and are in good agreement with the experimental data.In this study,self-consistent evaluation data for each reaction were obtained using multi-channel and multi-energy fitting.In particular,the error propagation theory of generalized least squares was used to determine the error of the evaluation data and the covariance matrix of the integral cross section.This R-matrix analysis for the 5 He system has three features.First,for the first time,the error in the evaluation data of the T(d,n)^(4)He reaction cross section and the covariance matrix of the integral cross section are provided.Second,we used only one set of R-matrix parameters to depict the reaction cross section of each reaction channel of the 5 He system for the entire energy region in our work.Third,in this evaluation,we considered some of the latest measured experimental data,especially after 2000.The T(d,n)^(4)He reaction cross section at 0.1 MeV and below was carefully studied.The effect of different energy levels in T(d,n)^(4)He was analyzed,with the energy levels 3/2^(+)making a major contribution to the cross section,and the role of the S-wave and P-wave from 3/2~-determines the lean forward trend of the angular distributions at 0.01–0.1 MeV.展开更多
Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:pla...Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:plastic deformation and shock-induced phase transitions.The underlying mechanisms of these processes are still poorly understood.Revealing these mechanisms remains challenging for experimental approaches.Non-equilibrium molecular dynamics(NEMD)simulations are an alternative theoretical tool for studying dynamic responses,as they capture atomic-scale mechanisms such as defect evolution and deformation pathways.However,due to the limited accuracy of empirical interatomic potentials,the reliability of previous NEMD studies has been questioned.Using our newly developed machine learning potential for Pb-Sn alloys,we revisited the microstructural evolution in response to shock loading under various shock orientations.The results reveal that shock loading along the[001]orientation of Pb exhibits a fast,reversible,and massive phase transition and stacking-fault evolution.The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation.Loading along the[011]orientation leads to slow,irreversible plastic deformation,and a localized FCC-BCC phase transition in the Pitsch orientation relationship.This study provides crucial theoretical insights into the dynamic mechanical response of Pb,offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.展开更多
With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this ...With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this study,the effects of X-ray beam size and photon energy on the accuracy of critical dimension measurements were investigated.Critical dimensions measured using beams with different spot sizes showed different deviations from the expected values.Beam sizes that were either too large or too small did not improve confidence intervals.As the incident energy increased,the X-ray transmission rate increased,while the scattering cross section decreased,resulting in a gradual decrease in the signal-to-noise ratio of the diffraction peaks,which reduced the accuracy of the CD-SAXS measurements.An optimal accuracy was obtained at 12 keV with a smaller beam size.Using an effective trapezoid model,the results yielded an average pitch of 100.4±0.2 nm,width of 49.8±0.2 nm,height of 130.0±0.2 nm,and a sidewall angle below 1.1°±0.1°.These results provide crucial guidance for the future development of CD-SAXS laboratories and the construction of X-ray machines as well as robust support for research in related fields.展开更多
Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for ...Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals that the SCR’s average density exerts a profound impact on its start-up flow threshold,channel flow rate,resistance to fuel density fluctuations,and response characteristics.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.展开更多
The unique advantage of x-ray ghost imaging(XGI)is its potential in low dose radiology.One of the practical ways to reduce the radiation exposure is to reduce the measurements while remaining sufficient image quality....The unique advantage of x-ray ghost imaging(XGI)is its potential in low dose radiology.One of the practical ways to reduce the radiation exposure is to reduce the measurements while remaining sufficient image quality.Synthetic aperture x-ray ghost imaging(SAXGI)is invented to achieve megapixel XGI with limited measurements,which is expected to implement XGI simultaneously with large field of view and low radiation exposure.In this paper,we experimentally investigate the effect of measurements reduction on the spatial resolution and image quality of SAXGI with standard sample and biomedical specimen.The results with a resolution chart demonstrated that at 360 measurements,SAXGI successfully retrieved the sample image of 1960×1960 pixels with spatial resolution of 4μm.With measurement reduction,the spatial resolution deteriorates but the sparser structures are still discernable.Even with measurements reduced to 10,a spatial resolution of 10μm can still be achieved by SAXGI.A biomedical sample of a fish specimen is employed to evaluate the method and the fish image of 2000×1000 pixels with an SSIM of 0.962 is reconstructed by SAXGI with 770measurements,corresponding to an accumulative exposure reduction of more than 2 times.With the measurements reduced to 10 which corresponds to 1/160 of the accumulative radiation exposure for conventional radiology,bulky structure like the fish skeleton can still be definitely discerned and the SSIM for the reconstructed image still retained 0.9179.Results of this paper demonstrate that measurements reduction is practicable for the radiation exposure reduction of the sample,which implicates that SAXGI with limited measurements is an efficient solution for low dose radiology.展开更多
Preserving beam quality during the transport of high-brightness electron bunches is crucial for advanced accelerator applications,such as particle colliders,free-electron lasers,and recirculating linacs.However,cohere...Preserving beam quality during the transport of high-brightness electron bunches is crucial for advanced accelerator applications,such as particle colliders,free-electron lasers,and recirculating linacs.However,coherent synchrotron radiation(CSR)significantly degrades beam quality when electron bunches pass through multi-bend isochronous beamlines,particularly for short bunches with non-ideal longitudinal profiles.Although several methods have been proposed to mitigate CSR effects,most rely on small-angle approximations or are limited to idealized bunch profiles.In this study,we present two improved methods for designing isochronous triple-bend achromat(TBA)beamlines that effectively mitigate CSR-induced emittance growth and longitudinal profile distortion without relying on small-angle approximations.The first method,an enhanced integral optimization approach,simplifies numerical optimization and can accurately handle larger deflection angles,making it suitable for practical applications that require flexible lattice configurations.The second method,an optimized I-matrix approach,completely cancels steady-state and transient CSR kicks through specific matrix constraints and higher-order dispersion optimization,enabling effective CSR suppression even with very large deflection angles.Systematic simulations demonstrate that both methods achieve excellent preservation of transverse emittance and longitudinal profiles.展开更多
The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)is currently under construction as one of the world’s most advanced hard X-ray free-electron laser facilities.The timing system,as an essential ...The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)is currently under construction as one of the world’s most advanced hard X-ray free-electron laser facilities.The timing system,as an essential part of the free-electron laser facility,provides precise timing of trigger pulse signals for a range of devices to ensure that particles are generated and accelerated to the designed energy while enabling the precise measurement of beam parameters.To precisely distribute and synchronize the 1.003086 MHz(1300/1296)timing signals over a distance of approximately 3.1 km based on White Rabbit technology,three technical routes have been proposed.This paper begins with a description of the design and development process of the timing system for the SHINE project,which culminates with the determination of the design scheme.During the installation and commissioning of the timing system,the jitter accuracy of the timing signal was tested and found to be less than 10 ps,which meets the requirements of the project.Furthermore,the precise clock synchronization signal provided by the timing system supported the joint debugging of various related systems and realization of beam acquisition.展开更多
When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.Howe...When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.However,the key to the efficiency and return on investment of this hybrid energy system lies in the expected lifetime of the SOEC.This study assessed Ni-YSZ|YSZ|GDC|LSC fuel electrode support cells’long-term stability during electrolysis at 650℃with a current density of−0.5Acm^(−2)over 1818 h.The average voltage degradation rate of 2.63%kh^(−1)unfolded in two phases:an initial rapid decay(90 to 1120 h at 3.58%kh^(−1))and a stable decay(1120 to 1818 h at 2.14%kh^(−1)),emphasizing SOECs’probability coupling with nuclear reactors at 650℃.Post-1818-hour electrolysis revealed nickel particle formation associated with Ni(OH)_(x)diffusion and re-deposition,alongside a strontium-containing layer causing interface cracking.Despite minimal strontium segregation in the EDS,XPS data indicated surface segregation of Sr.This study provides crucial insights into prolonged SOEC operation,highlighting both its potential and challenges.展开更多
An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achievin...An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.展开更多
The single electron capture processes in Si^(3,4+)+He collisions have been investigated theoretically employing the two-center atomic orbital close-coupling method in the energy range 0.01-100 keV/u.Total and state-se...The single electron capture processes in Si^(3,4+)+He collisions have been investigated theoretically employing the two-center atomic orbital close-coupling method in the energy range 0.01-100 keV/u.Total and state-selective electron capture cross sections for the dominant and subdominant reaction channels are calculated and compared with the available experimental and theoretical data.For the total charge transfer cross sections,the present results show better agreements with the available experimental data than the other theoretical ones in the overlapping energy region for both collision systems.For the state-selective cross sections,the present results for 3s and 3p states are in general agreement with the previous MOCC results in the low energy region for both collision systems.Furthermore,the cross sections for electron captured to the 3d,4l and 5l(l=0,1,...,n-1)states of Si^(2+)and Si^(3+)ions are first provided in a broad energy region in our work.These results are useful for the investigations in astrophysics.The datasets presented in this paper,including the total and state-selective electron capture cross sections of Si^(3,4+)+He collisions in 0.01-100 ke V/u,are openly available at https://doi.org/10.57760/sciencedb.j00113.00257.展开更多
Molten Salt Reactor(MSR) was selected as one of the six innovative nuclear reactors by the Generation IV International Forum(GIF).The circulating-fuel in the can-type molten salt fast reactor makes the neutronics and ...Molten Salt Reactor(MSR) was selected as one of the six innovative nuclear reactors by the Generation IV International Forum(GIF).The circulating-fuel in the can-type molten salt fast reactor makes the neutronics and thermo-hydraulics of the reactor strongly coupled and different from that of traditional solid-fuel reactors.In the present paper,a new coupling model is presented that physically describes the inherent relations between the neutron flux,the delayed neutron precursor,the heat transfer and the turbulent flow.Based on the model,integrating nuclear data processing,CAD modeling,structured and unstructured mesh technology,data analysis and visualization application,a three dimension steady state simulation code system(MSR3DS) for the can-type molten salt fast reactor is developed and validated.In order to demonstrate the ability of the code,the three dimension distributions of the velocity,the neutron flux,the delayed neutron precursor and the temperature were obtained for the simplified MOlten Salt Advanced Reactor Transmuter(MOSART) using this code.The results indicate that the MSR3DS code can provide a feasible description of multi-physical coupling phenomena in can-type molten salt fast reactor.Furthermore,the code can well predict the flow effect of fuel salt and the transport effect of the turbulent diffusion.展开更多
Axial gas-liquid separators have been adopted in fission gas removal systems for the development of thorium molten salt reactors. In our previous study, we observed an unsteady flow phenomenon in which the flow patter...Axial gas-liquid separators have been adopted in fission gas removal systems for the development of thorium molten salt reactors. In our previous study, we observed an unsteady flow phenomenon in which the flow pattern is directly dependent on the backpressure in a gas-liquid separator; however, the underlying flow mechanism is still unknown. In order to move a step further in clarifying how the flow pattern evolves with a variation in backpressure, a large eddy simulation(LES) was adopted to study the flow field evolution. In the simulation, an artificial boundary was applied at the separator outlet under the assumption that the backpressure increases linearly. The numerical results indicate that the unsteady flow feature is captured by the LES approach, and the flow transition is mainly due to the axial velocity profile redistribution induced by the backpressure variation. With the increase in backpressure,the axial velocity near the downstream orifice transits from negative to positive. This change in the axial velocity sign forces the unstable spiral vortex to become a stable rectilinear vortex.展开更多
The physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created ...The physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created by ionization of a low-density plastic foam by four high-energy(3.2 kJ)laser beams.An interaction beam is fired with a delay permitting evaluation of the excitation of parametric instabilities at different stages of plasma evolution.Multiple diagnostics are used for plasma characterization,scattered radiation,and accelerated electrons.The experimental results are analyzed with radiation hydrodynamic simulations that take account of foam ionization and homogenization.The measured level of stimulated Raman scattering is almost one order of magnitude larger than that measured in experiments with gasbags and hohlraums on the same installation,possibly because of a greater plasma density.Notable amplification is achieved in high-intensity speckles,indicating the importance of implementing laser temporal smoothing techniques with a large bandwidth for controlling laser propagation and absorption.展开更多
基金National Natural Science Foundation of China(51801227,52071331)。
文摘The influence of homogenization parameters on element segregation,dendritic structure,and the precipitate evolution in the GH3535-0.08wt%Y alloy was investigated.Additionally,some specific homogenization parameters were maintained constant throughout the experiments.Results indicate that the heat treatment at 1150℃for 10 h is the optimal homogenization condition.Following this optimal treatment,dendrite structures and element segregation are eliminated.Furthermore,both SiC and Y_(5)Si_(3)precipitates in the as-cast alloy decrease significantly.Conversely,the homogenization at 1188℃induces overheating defects within the alloy.Although SiC and Y_(5)Si_(3)phases also decrease,some large M6C phases can still be observed,adversely affecting subsequent forging processes.
基金supported by the National Natural Science Foundation of China(Grant No.12172063).
文摘The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.
基金supported by Russian Science Foundation Grant No.24-62-00032.
文摘Experiments with interacting high-velocity flows in a laser plasma can help answer fundamental questions in plasma physics and improve understanding of the mechanisms behind some astrophysical phenomena,such as the formation of collisionless shock waves,deceleration of accretion flows,and evolution of solar and stellar flares.This work presents the first direct experimental observations of stagnation and redirection of counterstreaming flows(jets)of laser plasma induced by intense laser pulses with intensity I~2×10^(18) W/cm^(2).Hybrid particlein-cell-fluid modeling,which takes into account the kinetic effects of ion motion and the evolution of the pressure tensor for electrons,demonstrates the compression of counterdirected toroidal self-generated magnetic fields embedded in counterstreaming plasma flows.The enhancement of the toroidal magnetic field in the interaction region results in plasma flow stagnation and redirection of the jets across the line of their initial propagation.
基金supported by the National Natural Science Foundation of China(NSFC)(No.12075308)。
文摘At high count rates,pile-up events involving neutron and gamma signals result in inaccurate neutron counting and distortions in the energy spectrum.Additionally,a bipolar cusp-like pulse shaping algorithm based on an unfolding synthesis technique was proposed.This algorithm exhibits a narrow pulse shape,and the parallel design of the dual algorithms enables the recovery of pile-up signal amplitudes while preserving the distinct characteristics of neutron and gamma signals.The simplicity of the algorithm facilitates real-time neutron/gamma discrimination on an FPGA,allowing the energy spectra to be updated with each incoming signal.Furthermore,the algorithm can be readily tailored to various experimental conditions by adjusting the decay time constants.Multi-objective optimization reduces the need for manual parameter tuning by rapidly identifying the optimal parameters.Testing with a^(241)Am-Be neutron source and a NaIL scintillator yielded a figure of merit(FoM)value of 2.11 and produced a clear energy spectrum even at high count rates.
基金supported by the Jiangxi Provincial Natural Science Foundation of China(Grant number 20224BAB204049)the Fund Project of Jiangxi Provincial Department of Education(Grant number GJJ2200602)the National Natural Science Foundation of China(Grant number 52205194)。
文摘The laser-clad Fe45 alloy coating inherently comprises multiple crystalline phases,resulting in a heterogeneous microstructural distribution that influences its performance.In this study,the rare earth yttria(Y_(2)O_(3))was employed to modify laser-clad Fe45 alloy coatings,and the effects of Y_(2)O_(3) addition on their microstructure,microhardness,and tribological properties were investigated.As the Y_(2)O_(3) content increases from 0%to 0.3wt.%,the dominant microstructure transforms from columnar crystals to fine cellular and equiaxed crystals.The modified coating with 0.3wt.%Y_(2)O_(3) achieves a surface hardness of 568 HV_(0.3)and a wear volume of 1,735.41 um~3,representing a 14.06%increase in hardness and a 51.16%reduction in wear volume compared to the undoped coating.Further increasing the Y_(2)O_(3) content from 0.3wt.%to 0.9wt.%gradually leads to the emergence of a coarser feather-like microstructure,characterized by a dendritic framework with inter-dendritic equiaxed crystals.Concurrently,both the hardness and wear resistance of the coating decrease.Nevertheless,all Y_(2)O_(3)-modified coatings surpass the undoped Fe45 coating in both hardness and wear resistance.Appropriate Y_(2)O_(3) doping effectively refines the Fe45 alloy coating's microstru cture and induces lattice distortion,thereby enhancing its hardness and wear resistance.
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2020261)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02010000)the Young Potential Program of the Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.SINAP-YXJH-202412)。
文摘Knowing the precise relationship between fuel loading and reactivity is essential for guiding reactor criticality extrapolation and online refueling in molten salt reactors(MSRs).This study aims to explore and explain the linear relationship between reactivity and the reciprocal of uranium concentration in thermal-spectrum MSRs.By applying neutron balance theory,we analyzed the neutron absorption cross sections of various nuclides in single-lattice models with varying fuel concentrations.Our findings reveal a simple linear correlation between reactivity and the reciprocal of uranium concentration,which can be explained from the perspective of nuclear reaction cross sections that adhere to the 1/v law in the thermal neutron spectrum.Furthermore,we identified that the neutron absorption single-group cross sections of structural materials and carrier salts exhibit an approximately linear relationship with the fission single-group cross section of ^(235) U;similarly,the reciprocal of ^(235)U’s fission cross section exhibits an approximately linear relationship with uranium concentration.This linear relationship deviates as the volume fraction of molten salt increases,due to a greater proportion of neutrons being captured in the resonance energy spectrum.However,it remains valid for molten salt volume fractions up to 25%and demonstrates broad applicability in the physical design and operation of thermal molten salt reactors.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB3700602)the Jiaxing Key Research and Development Program(Grant No.2022BZ10010).
文摘The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation of Ti-containing inclusions,enhancing heterogeneous nucleation and promoting equiaxed dendritic growth in 347H stainless steel.Thermal simulation experiments indicated that the equiaxed crystal ratios increased notably with Ti content;samples with 0.06,0.12,and 0.36 wt.%Ti exhibited equiaxed ratios of 18%,24%,and 41%,respectively.Three primary inclusion types—TiN,Al_(2)O_(3)-TiN,and TiO_(x)-TiN—were identified at the cores of equiaxed dendrites,with nucleation core sizes predominantly ranging from 0.5 to 8μm.Among the tested samples,the 0.36 wt.%Ti addition produced the highest nucleation core density.Increasing Ti content significantly elevated dendrite tip undercooling from 2.6 K(0.06 wt.%Ti)to 10.8 K(0.36 wt.%Ti),accelerating solidification front instability and thus enhancing heterogeneous nucleation.Additionally,higher Ti content increased the divergence angle between adjacent columnar dendrites,further promoting the columnar-to-equiaxed transition(CET).
基金supported by Science Challenge Project(No.TZ20180001)。
文摘Based on the generalized reduced R-matrix theory,the R-matrix analysis code(RAC program)was used to analyze the experimental data of all the nuclear reaction channels related to the 5 He system.The current calculations provide accurate and reliable evaluation data and are in good agreement with the experimental data.In this study,self-consistent evaluation data for each reaction were obtained using multi-channel and multi-energy fitting.In particular,the error propagation theory of generalized least squares was used to determine the error of the evaluation data and the covariance matrix of the integral cross section.This R-matrix analysis for the 5 He system has three features.First,for the first time,the error in the evaluation data of the T(d,n)^(4)He reaction cross section and the covariance matrix of the integral cross section are provided.Second,we used only one set of R-matrix parameters to depict the reaction cross section of each reaction channel of the 5 He system for the entire energy region in our work.Third,in this evaluation,we considered some of the latest measured experimental data,especially after 2000.The T(d,n)^(4)He reaction cross section at 0.1 MeV and below was carefully studied.The effect of different energy levels in T(d,n)^(4)He was analyzed,with the energy levels 3/2^(+)making a major contribution to the cross section,and the role of the S-wave and P-wave from 3/2~-determines the lean forward trend of the angular distributions at 0.01–0.1 MeV.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1004300)the National Natural Science Foundation of China(Grant No.12404004)。
文摘Lead(Pb)is a typical low-melting-point ductile metal and serves as an important model material in the study of dynamic responses.Under shock-wave loading,its dynamic mechanical behavior comprises two key phenomena:plastic deformation and shock-induced phase transitions.The underlying mechanisms of these processes are still poorly understood.Revealing these mechanisms remains challenging for experimental approaches.Non-equilibrium molecular dynamics(NEMD)simulations are an alternative theoretical tool for studying dynamic responses,as they capture atomic-scale mechanisms such as defect evolution and deformation pathways.However,due to the limited accuracy of empirical interatomic potentials,the reliability of previous NEMD studies has been questioned.Using our newly developed machine learning potential for Pb-Sn alloys,we revisited the microstructural evolution in response to shock loading under various shock orientations.The results reveal that shock loading along the[001]orientation of Pb exhibits a fast,reversible,and massive phase transition and stacking-fault evolution.The behavior of Pb differs from previous studies by the absence of twinning during plastic deformation.Loading along the[011]orientation leads to slow,irreversible plastic deformation,and a localized FCC-BCC phase transition in the Pitsch orientation relationship.This study provides crucial theoretical insights into the dynamic mechanical response of Pb,offering a theoretical input for understanding the microstructure-performance relationship under extreme conditions.
基金supported by the National Natural Science Foundation of China(No.12175295)the National Key R&D Program of China(2021YFA1601000)the Shanghai Municipal Science and Technology Major Project。
文摘With the development of the semiconductor industry below the 7 nm scale,critical dimension small-angle X-ray scattering(CD-SAXS)has emerged as a powerful tool for quantitatively measuring nanoscale deviations.In this study,the effects of X-ray beam size and photon energy on the accuracy of critical dimension measurements were investigated.Critical dimensions measured using beams with different spot sizes showed different deviations from the expected values.Beam sizes that were either too large or too small did not improve confidence intervals.As the incident energy increased,the X-ray transmission rate increased,while the scattering cross section decreased,resulting in a gradual decrease in the signal-to-noise ratio of the diffraction peaks,which reduced the accuracy of the CD-SAXS measurements.An optimal accuracy was obtained at 12 keV with a smaller beam size.Using an effective trapezoid model,the results yielded an average pitch of 100.4±0.2 nm,width of 49.8±0.2 nm,height of 130.0±0.2 nm,and a sidewall angle below 1.1°±0.1°.These results provide crucial guidance for the future development of CD-SAXS laboratories and the construction of X-ray machines as well as robust support for research in related fields.
基金supported by Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020261)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA02010000)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.SINAP-YXJH-202412).
文摘Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals that the SCR’s average density exerts a profound impact on its start-up flow threshold,channel flow rate,resistance to fuel density fluctuations,and response characteristics.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1603601,2021YFF0601203,and 2021YFA1600703)。
文摘The unique advantage of x-ray ghost imaging(XGI)is its potential in low dose radiology.One of the practical ways to reduce the radiation exposure is to reduce the measurements while remaining sufficient image quality.Synthetic aperture x-ray ghost imaging(SAXGI)is invented to achieve megapixel XGI with limited measurements,which is expected to implement XGI simultaneously with large field of view and low radiation exposure.In this paper,we experimentally investigate the effect of measurements reduction on the spatial resolution and image quality of SAXGI with standard sample and biomedical specimen.The results with a resolution chart demonstrated that at 360 measurements,SAXGI successfully retrieved the sample image of 1960×1960 pixels with spatial resolution of 4μm.With measurement reduction,the spatial resolution deteriorates but the sparser structures are still discernable.Even with measurements reduced to 10,a spatial resolution of 10μm can still be achieved by SAXGI.A biomedical sample of a fish specimen is employed to evaluate the method and the fish image of 2000×1000 pixels with an SSIM of 0.962 is reconstructed by SAXGI with 770measurements,corresponding to an accumulative exposure reduction of more than 2 times.With the measurements reduced to 10 which corresponds to 1/160 of the accumulative radiation exposure for conventional radiology,bulky structure like the fish skeleton can still be definitely discerned and the SSIM for the reconstructed image still retained 0.9179.Results of this paper demonstrate that measurements reduction is practicable for the radiation exposure reduction of the sample,which implicates that SAXGI with limited measurements is an efficient solution for low dose radiology.
基金supported by the Natural Science Foundation of Shanghai(No.22ZR1470200)National Natural Science Foundation of China(Nos.12125508,12122514,12541503,12241501)Shanghai Pilot Program for Basic Research—Chinese Academy of Sciences,Shanghai Branch(JCYJ-SHFY-2021-010)。
文摘Preserving beam quality during the transport of high-brightness electron bunches is crucial for advanced accelerator applications,such as particle colliders,free-electron lasers,and recirculating linacs.However,coherent synchrotron radiation(CSR)significantly degrades beam quality when electron bunches pass through multi-bend isochronous beamlines,particularly for short bunches with non-ideal longitudinal profiles.Although several methods have been proposed to mitigate CSR effects,most rely on small-angle approximations or are limited to idealized bunch profiles.In this study,we present two improved methods for designing isochronous triple-bend achromat(TBA)beamlines that effectively mitigate CSR-induced emittance growth and longitudinal profile distortion without relying on small-angle approximations.The first method,an enhanced integral optimization approach,simplifies numerical optimization and can accurately handle larger deflection angles,making it suitable for practical applications that require flexible lattice configurations.The second method,an optimized I-matrix approach,completely cancels steady-state and transient CSR kicks through specific matrix constraints and higher-order dispersion optimization,enabling effective CSR suppression even with very large deflection angles.Systematic simulations demonstrate that both methods achieve excellent preservation of transverse emittance and longitudinal profiles.
基金supported by SHINE and Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02).
文摘The Shanghai High Repetition Rate XFEL and Extreme Light Facility(SHINE)is currently under construction as one of the world’s most advanced hard X-ray free-electron laser facilities.The timing system,as an essential part of the free-electron laser facility,provides precise timing of trigger pulse signals for a range of devices to ensure that particles are generated and accelerated to the designed energy while enabling the precise measurement of beam parameters.To precisely distribute and synchronize the 1.003086 MHz(1300/1296)timing signals over a distance of approximately 3.1 km based on White Rabbit technology,three technical routes have been proposed.This paper begins with a description of the design and development process of the timing system for the SHINE project,which culminates with the determination of the design scheme.During the installation and commissioning of the timing system,the jitter accuracy of the timing signal was tested and found to be less than 10 ps,which meets the requirements of the project.Furthermore,the precise clock synchronization signal provided by the timing system supported the joint debugging of various related systems and realization of beam acquisition.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0400000)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2021253)+1 种基金the Major Science and Technology Projects of China National Offshore Oil Corporation Limited during the 14th Five Year Plan(No.KJGG-2022-12-CCUS-030500)the Photon Science Center for Carbon Neutrality of Chinese Academy of Science.
文摘When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.However,the key to the efficiency and return on investment of this hybrid energy system lies in the expected lifetime of the SOEC.This study assessed Ni-YSZ|YSZ|GDC|LSC fuel electrode support cells’long-term stability during electrolysis at 650℃with a current density of−0.5Acm^(−2)over 1818 h.The average voltage degradation rate of 2.63%kh^(−1)unfolded in two phases:an initial rapid decay(90 to 1120 h at 3.58%kh^(−1))and a stable decay(1120 to 1818 h at 2.14%kh^(−1)),emphasizing SOECs’probability coupling with nuclear reactors at 650℃.Post-1818-hour electrolysis revealed nickel particle formation associated with Ni(OH)_(x)diffusion and re-deposition,alongside a strontium-containing layer causing interface cracking.Despite minimal strontium segregation in the EDS,XPS data indicated surface segregation of Sr.This study provides crucial insights into prolonged SOEC operation,highlighting both its potential and challenges.
基金financially supported by the National Science and Technology Major Project(No.2024ZD1404705)。
文摘An advanced AlCrSiN/AlCrN/CrN/Cr multilayer coating was developed via hybrid multiarc ion plating and high-power impulse magnetron sputtering.The multilayer design enhanced the substrate-coating compatibility,achieving a critical load of 87.8 N.Silicon doping induced nanocrystallization and amorphization,increasing the hardness to 26 GPa.At high temperatures,a nanoscale Cr-rich(Cr,Al)_(2)O_(3) layer was formed,effectively inhibiting oxygen diffusion.The coating underwent unique phase transformations,during which Cr_(2)N and amorphous Si3N4 were converted into dispersed SiCr_(3) nanoparticles,which stabilized Cr atoms and suppressed their outward diffusion.Ab initio molecular dynamics simulations revealed that Cr atoms exhibited higher chemical activity and oxygen-capture capability than Al atoms and Si atoms served as diffusion barriers by pinning onto the oxidized surface,considerably improving the oxidation resistance of the coating.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1602504)the National Natural Science Foundation of China(Grant Nos.12274040 and U2430208)。
文摘The single electron capture processes in Si^(3,4+)+He collisions have been investigated theoretically employing the two-center atomic orbital close-coupling method in the energy range 0.01-100 keV/u.Total and state-selective electron capture cross sections for the dominant and subdominant reaction channels are calculated and compared with the available experimental and theoretical data.For the total charge transfer cross sections,the present results show better agreements with the available experimental data than the other theoretical ones in the overlapping energy region for both collision systems.For the state-selective cross sections,the present results for 3s and 3p states are in general agreement with the previous MOCC results in the low energy region for both collision systems.Furthermore,the cross sections for electron captured to the 3d,4l and 5l(l=0,1,...,n-1)states of Si^(2+)and Si^(3+)ions are first provided in a broad energy region in our work.These results are useful for the investigations in astrophysics.The datasets presented in this paper,including the total and state-selective electron capture cross sections of Si^(3,4+)+He collisions in 0.01-100 ke V/u,are openly available at https://doi.org/10.57760/sciencedb.j00113.00257.
基金Supported by the"Strategic Priority Research Program"of the Chinese Academy of Science(No.XD02001004)
文摘Molten Salt Reactor(MSR) was selected as one of the six innovative nuclear reactors by the Generation IV International Forum(GIF).The circulating-fuel in the can-type molten salt fast reactor makes the neutronics and thermo-hydraulics of the reactor strongly coupled and different from that of traditional solid-fuel reactors.In the present paper,a new coupling model is presented that physically describes the inherent relations between the neutron flux,the delayed neutron precursor,the heat transfer and the turbulent flow.Based on the model,integrating nuclear data processing,CAD modeling,structured and unstructured mesh technology,data analysis and visualization application,a three dimension steady state simulation code system(MSR3DS) for the can-type molten salt fast reactor is developed and validated.In order to demonstrate the ability of the code,the three dimension distributions of the velocity,the neutron flux,the delayed neutron precursor and the temperature were obtained for the simplified MOlten Salt Advanced Reactor Transmuter(MOSART) using this code.The results indicate that the MSR3DS code can provide a feasible description of multi-physical coupling phenomena in can-type molten salt fast reactor.Furthermore,the code can well predict the flow effect of fuel salt and the transport effect of the turbulent diffusion.
基金supported by the National Natural Science Foundation of China(Nos.11535009 and 51406114)
文摘Axial gas-liquid separators have been adopted in fission gas removal systems for the development of thorium molten salt reactors. In our previous study, we observed an unsteady flow phenomenon in which the flow pattern is directly dependent on the backpressure in a gas-liquid separator; however, the underlying flow mechanism is still unknown. In order to move a step further in clarifying how the flow pattern evolves with a variation in backpressure, a large eddy simulation(LES) was adopted to study the flow field evolution. In the simulation, an artificial boundary was applied at the separator outlet under the assumption that the backpressure increases linearly. The numerical results indicate that the unsteady flow feature is captured by the LES approach, and the flow transition is mainly due to the axial velocity profile redistribution induced by the backpressure variation. With the increase in backpressure,the axial velocity near the downstream orifice transits from negative to positive. This change in the axial velocity sign forces the unstable spiral vortex to become a stable rectilinear vortex.
基金This project was partially supported by the Advanced Research Using High Intensity Laser Produced Photons and Particles(ADONIS)project(Grant No.CZ.02.1.01/0.0/0.0/16_019/0000789)the CAAS project(Grant No.CZ.02.1.01/0.0/0.0/16_019/0000778)+3 种基金both from the European Regional Development FundThe results of the LQ1606 project were partially obtained with the financial support from the Ministry of Education,Youth and Sports as part of targeted support from the National Programme of Sustainability IIThe authors acknowledge support from the National Natural Science Foundation of China(Grant Nos.11775033,11875241,11975215,11905204,12035002)the Laser Fusion Research Center Funds for Young Talents(Grant No.RCFPD3-2019-6).
文摘The physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created by ionization of a low-density plastic foam by four high-energy(3.2 kJ)laser beams.An interaction beam is fired with a delay permitting evaluation of the excitation of parametric instabilities at different stages of plasma evolution.Multiple diagnostics are used for plasma characterization,scattered radiation,and accelerated electrons.The experimental results are analyzed with radiation hydrodynamic simulations that take account of foam ionization and homogenization.The measured level of stimulated Raman scattering is almost one order of magnitude larger than that measured in experiments with gasbags and hohlraums on the same installation,possibly because of a greater plasma density.Notable amplification is achieved in high-intensity speckles,indicating the importance of implementing laser temporal smoothing techniques with a large bandwidth for controlling laser propagation and absorption.
