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RSS2021 Vol. 33, No. 1
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2021,
33: 1-1.
2021,
33: 012001.
doi: 10.11884/HPLPB202133.200173
Abstract:
Laser fusion, likely the ultimate solution to the crisis of human energy, is highly valued by the international community and has always been the focus of international research. It turns out that the biggest scientific obstacle of laser fusion is the effective control of the high-energy-density nonlinear flows during implosions. The research of high-energy-density nonlinear flows covers many different fields, such as high-energy-density physics, plasma physics, fluid mechanics, computing science, strong impact physics, and high pressure atomic physics. Meanwhile, the capability of multi-material and multi-scale numerical simulations as well as large laser facility with high output power is also needed. As an emerging research field, it is full of all kinds of novel phenomena to be explored. In addition, hydrodynamic instabilities and the subsequent turbulent mixing in high-energy-density flows, are also important processes in astrophysical phenomena (e.g., galaxy collision and merging, stellar evolution, formation of protostars and supernova explosion) and involve with the core content of astrophysics. This paper reviews, firstly the status and progress, as well as the challenges and opportunities of high-energy-density nonlinear flows research. Secondly, it introduces hydrodynamic instabilities during implosions in central ignition laser fusion, among which, key factors related to the bottleneck of implosion performance of the National Ignition Facility (NIF) in the United States are condensed. Next, it summarizes the development of hydrodynamic instability experiments in laser fusion abroad. Finally, it lists some key achievements on the fundamental issues of hydrodynamic instabilities by the laser fusion implosion physics team in China over the last three years. This team has been engaged in the research and control of nonlinear flows in laser fusion implosions, as well as the research and design of target physics. A lot of improvements have been made in recent years on the theoretical analysis and numerical simulation of outstanding issues for hydrodynamic instabilities in laser fusion implosions, and the design and analysis of experiments on large lasers, which greatly promoted the development of this research direction in China.
Laser fusion, likely the ultimate solution to the crisis of human energy, is highly valued by the international community and has always been the focus of international research. It turns out that the biggest scientific obstacle of laser fusion is the effective control of the high-energy-density nonlinear flows during implosions. The research of high-energy-density nonlinear flows covers many different fields, such as high-energy-density physics, plasma physics, fluid mechanics, computing science, strong impact physics, and high pressure atomic physics. Meanwhile, the capability of multi-material and multi-scale numerical simulations as well as large laser facility with high output power is also needed. As an emerging research field, it is full of all kinds of novel phenomena to be explored. In addition, hydrodynamic instabilities and the subsequent turbulent mixing in high-energy-density flows, are also important processes in astrophysical phenomena (e.g., galaxy collision and merging, stellar evolution, formation of protostars and supernova explosion) and involve with the core content of astrophysics. This paper reviews, firstly the status and progress, as well as the challenges and opportunities of high-energy-density nonlinear flows research. Secondly, it introduces hydrodynamic instabilities during implosions in central ignition laser fusion, among which, key factors related to the bottleneck of implosion performance of the National Ignition Facility (NIF) in the United States are condensed. Next, it summarizes the development of hydrodynamic instability experiments in laser fusion abroad. Finally, it lists some key achievements on the fundamental issues of hydrodynamic instabilities by the laser fusion implosion physics team in China over the last three years. This team has been engaged in the research and control of nonlinear flows in laser fusion implosions, as well as the research and design of target physics. A lot of improvements have been made in recent years on the theoretical analysis and numerical simulation of outstanding issues for hydrodynamic instabilities in laser fusion implosions, and the design and analysis of experiments on large lasers, which greatly promoted the development of this research direction in China.
2021,
33: 012002.
doi: 10.11884/HPLPB202133.200128
Abstract:
The pinch devices based on pulsed power technique can produce extreme conditions of temperature, pressure, density and strong radiation in spatial scale of cm and time scale of 100 ns. Numerous high energy density physics experiments are carried out on the 10 MA level pulsed power facility constructed at Institute of Fluid Physics, CAEP, which utilize a wide range of load configurations. Z-pinch driven dynamic hohlraums produce high temperature radiation field required for conducting inertial confinement fusion (ICF) experiments. Characteristics of implosion dynamics of metallic foils and solid liners are investigated and presented. Implosions using medium and low Z materials produce considerable K-shell line emissions, which are used to perform X-ray thermo-mechanical effect experiments. Magnetically driven isentropic compression and shock loading provide new experimental capabilities for research on dynamic materials properties. Ring diodes and reflex triodes are adopted to produce large X-ray or gamma-ray dose (rate) from bremsstrahlung. Magnetically driven radial metallic foils are used to simulate the formation of stellar jets and its radiation relevant to astrophysics. Additionally, experimental results of formation of preheated magnetized plasma target on a field reverse configuration (FRC) magnetized target fusion device are presented.
The pinch devices based on pulsed power technique can produce extreme conditions of temperature, pressure, density and strong radiation in spatial scale of cm and time scale of 100 ns. Numerous high energy density physics experiments are carried out on the 10 MA level pulsed power facility constructed at Institute of Fluid Physics, CAEP, which utilize a wide range of load configurations. Z-pinch driven dynamic hohlraums produce high temperature radiation field required for conducting inertial confinement fusion (ICF) experiments. Characteristics of implosion dynamics of metallic foils and solid liners are investigated and presented. Implosions using medium and low Z materials produce considerable K-shell line emissions, which are used to perform X-ray thermo-mechanical effect experiments. Magnetically driven isentropic compression and shock loading provide new experimental capabilities for research on dynamic materials properties. Ring diodes and reflex triodes are adopted to produce large X-ray or gamma-ray dose (rate) from bremsstrahlung. Magnetically driven radial metallic foils are used to simulate the formation of stellar jets and its radiation relevant to astrophysics. Additionally, experimental results of formation of preheated magnetized plasma target on a field reverse configuration (FRC) magnetized target fusion device are presented.
2021,
33: 012003.
doi: 10.11884/HPLPB202133.200137
Abstract:
Hydrogen is the most abundant element in nature and an important object of astrophysics and ICF research. This paper briefly presents an overview of the research progress in wide-range equation of state and especially comments assessment of the most recent shock compression experiments on Omega laser facility and the theoretical models. Based on the previous work, the wide-range equation of state of hydrogen is constructed by using the improved chemical free energy model, the first-principle numerical simulation results and the multi-parameter equation of state model, which is applicable in the temperature range of 20−108 K and the density range of 10−7−2000 g/cm3. Compared with experimental results, such as those of shock compression experiment, static high pressure isotherm experiment and sound velocity experiment, the newly-constructed wide-range equation of state for hydrogen has high confidence and provides high precision data for astrophysics, inertial confinement fusion, international thermonuclear experimental reactor and other engineering physics designs. The construction and validation method of the hydrogen wide-range equation of state can also be applied to its isotope deuterium. In comparison with current models published abroad, the deuterium wide-range equation of state constructed by this method is in better agreement with the experimental data of principal and secondary Hugoniot published in 2019. This paper also points out the temperature-density regimesthat need attention in future research.
Hydrogen is the most abundant element in nature and an important object of astrophysics and ICF research. This paper briefly presents an overview of the research progress in wide-range equation of state and especially comments assessment of the most recent shock compression experiments on Omega laser facility and the theoretical models. Based on the previous work, the wide-range equation of state of hydrogen is constructed by using the improved chemical free energy model, the first-principle numerical simulation results and the multi-parameter equation of state model, which is applicable in the temperature range of 20−108 K and the density range of 10−7−2000 g/cm3. Compared with experimental results, such as those of shock compression experiment, static high pressure isotherm experiment and sound velocity experiment, the newly-constructed wide-range equation of state for hydrogen has high confidence and provides high precision data for astrophysics, inertial confinement fusion, international thermonuclear experimental reactor and other engineering physics designs. The construction and validation method of the hydrogen wide-range equation of state can also be applied to its isotope deuterium. In comparison with current models published abroad, the deuterium wide-range equation of state constructed by this method is in better agreement with the experimental data of principal and secondary Hugoniot published in 2019. This paper also points out the temperature-density regimesthat need attention in future research.
2021,
33: 012004.
doi: 10.11884/HPLPB202133.200235
Abstract:
In recent years, the study of kinetic effects is a hot issue in the field of laser inertial confinement fusion, which helps to understand the deviation between experimental results and traditional fluid simulation. The temperature and density of the plasma in indirect-drive hohlraum span multiple orders of magnitude, and the composition of capsule is complex. In the local high temperature and low density region, the thermal non-equilibrium effect of particles becomes significant, which may indirectly affect the implosion performance. In this paper, the concept and some progress of kinetic effects in the ICF field are briefly reviewed.
In recent years, the study of kinetic effects is a hot issue in the field of laser inertial confinement fusion, which helps to understand the deviation between experimental results and traditional fluid simulation. The temperature and density of the plasma in indirect-drive hohlraum span multiple orders of magnitude, and the composition of capsule is complex. In the local high temperature and low density region, the thermal non-equilibrium effect of particles becomes significant, which may indirectly affect the implosion performance. In this paper, the concept and some progress of kinetic effects in the ICF field are briefly reviewed.
2021,
33: 012005.
doi: 10.11884/HPLPB202133.200339
Abstract:
Intense ion beams can quasi-isometrically heat any high-density sample and generate warm dense matter (WDM) with large scale, uniform state distribution without any shock wave inside. This kind of driver provides a new opportunity for the laboratory high energy density physics (HEDP) research. The typical intense ion beam accelerators around the world, as well as their critical parameters and research plans of HEDP study are introduced.The progress of ion driven WDM generation and evolution using PIC and hydrodynamic simulations is shown. The high energy electron beam radiography technique with high spatial resolution, high temporal evolution, and high penetrating ability is also introduced. The collisional and charge transfer processes of the interaction between low-to-medium energy ion and plasma are analyzed. The nonlinear effect during the intense ion beam stopping and transportation process are presented.
Intense ion beams can quasi-isometrically heat any high-density sample and generate warm dense matter (WDM) with large scale, uniform state distribution without any shock wave inside. This kind of driver provides a new opportunity for the laboratory high energy density physics (HEDP) research. The typical intense ion beam accelerators around the world, as well as their critical parameters and research plans of HEDP study are introduced.The progress of ion driven WDM generation and evolution using PIC and hydrodynamic simulations is shown. The high energy electron beam radiography technique with high spatial resolution, high temporal evolution, and high penetrating ability is also introduced. The collisional and charge transfer processes of the interaction between low-to-medium energy ion and plasma are analyzed. The nonlinear effect during the intense ion beam stopping and transportation process are presented.
2021,
33: 012006.
doi: 10.11884/HPLPB202133.200125
Abstract:
The issue of laser plasma instabilities (LPIs) including stimulated Raman scattering, stimulated Brillouin scattering and so on is one of the most fascinating subjects in laser plasma physics. In particular, LPIs may cause significant laser energy loss and produce hot electrons to preheat fusion targets, which affect target compression and fusion energy gain in laser-driven inertial confinement fusion. Recent experiments carried out on the National Ignition Facility, the largest laser facility in the world for laser fusion, indicate that the understanding and the control of LPIs are essential to the realization of laser fusion. In this paper, we present a review on recent studies of LPIs. Firstly, we retrospect the classical theoretical model of LPIs, which offers a good estimation of growth rate in the linear development stage. Then, we discuss some progresses on the understanding of LPIs in more complex and real scenarios, such as LPI development in the nonlinear regions, cascaded LPIs, multi-beam LPIs, and nonlinear couplings between LPIs. Following the exploration of LPI physics, we emphasize on the strategies for the control of LPIs, including beam smoothing techniques, temporal profile shaping, broadband laser, laser polarization rotation, external magnetic field and so on.
The issue of laser plasma instabilities (LPIs) including stimulated Raman scattering, stimulated Brillouin scattering and so on is one of the most fascinating subjects in laser plasma physics. In particular, LPIs may cause significant laser energy loss and produce hot electrons to preheat fusion targets, which affect target compression and fusion energy gain in laser-driven inertial confinement fusion. Recent experiments carried out on the National Ignition Facility, the largest laser facility in the world for laser fusion, indicate that the understanding and the control of LPIs are essential to the realization of laser fusion. In this paper, we present a review on recent studies of LPIs. Firstly, we retrospect the classical theoretical model of LPIs, which offers a good estimation of growth rate in the linear development stage. Then, we discuss some progresses on the understanding of LPIs in more complex and real scenarios, such as LPI development in the nonlinear regions, cascaded LPIs, multi-beam LPIs, and nonlinear couplings between LPIs. Following the exploration of LPI physics, we emphasize on the strategies for the control of LPIs, including beam smoothing techniques, temporal profile shaping, broadband laser, laser polarization rotation, external magnetic field and so on.
2021,
33: 012007.
doi: 10.11884/HPLPB202133.200140
Abstract:
In laser indirect-drive inertial confinement fusion (ICF), the interaction of high-intensity laser and under-dense plasmas will excite two stimulated scattering processes: stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). These processes are detrimental to ignition since they consume laser energy, break symmetry of the X-ray radiation, and produce energetic electrons. Therefore, comprehending the basic physics of the stimulated scattering processes and hence finding effective approaches to suppress them are great concerns in ICF research. This article introduces several theoretical models developed by Chinese researchers for studying stimulated scattering processes, as well as their applications in analysis of experimental data. These theoretical models, together with the experiments, play important roles in improving the physical understanding of the stimulated scattering processes.
In laser indirect-drive inertial confinement fusion (ICF), the interaction of high-intensity laser and under-dense plasmas will excite two stimulated scattering processes: stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS). These processes are detrimental to ignition since they consume laser energy, break symmetry of the X-ray radiation, and produce energetic electrons. Therefore, comprehending the basic physics of the stimulated scattering processes and hence finding effective approaches to suppress them are great concerns in ICF research. This article introduces several theoretical models developed by Chinese researchers for studying stimulated scattering processes, as well as their applications in analysis of experimental data. These theoretical models, together with the experiments, play important roles in improving the physical understanding of the stimulated scattering processes.
