1.Introduction to ablative TPS The Mars 2020 mission underscored the critical role of ablative Thermal Protection Systems(TPS)during atmospheric entry,where spacecraft encounter extreme aerodynamic heating.Established...1.Introduction to ablative TPS The Mars 2020 mission underscored the critical role of ablative Thermal Protection Systems(TPS)during atmospheric entry,where spacecraft encounter extreme aerodynamic heating.Established in the mid-20th century,blunt body theories led to the creation of ablative heat shields that effectively manage thermal loads through thermo-chemo-mechanical decomposition.This paper revisits the development and application of ablative TPS materials,which are single-mission solutions capable of withstanding entry velocities surpassing 10 km/s.展开更多
The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the pla...The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.展开更多
In the direct drive inertial confinement fusion(ICF)scheme,a rippled interface between the ablator and the deuterium–tritium ice fuel can feed out and form perturbation seeds for the ablative Rayleigh–Taylor instabi...In the direct drive inertial confinement fusion(ICF)scheme,a rippled interface between the ablator and the deuterium–tritium ice fuel can feed out and form perturbation seeds for the ablative Rayleigh–Taylor instability,with undesirable effects.However,the evolution of this instability remains insufficiently studied,and the effects of high-Z dopant on this instability remain unclear.In this paper,we develop a theoretical model to calculate the feedout seeds and describe this instability.Our theory suggests that the feedout seeds are determined by the ablation pressure and the adiabatic index,while the subsequent growth depends mainly on the ablation velocity.Two-dimensional radiation hydrodynamic simulations confirm our theory.It is shown that targets with high-Z dopant in the outer ablator exhibit more severe feedout seeds,because of their higher ionization compared with undoped targets.The X-ray pre-ablation in high-Z doped targets significantly suppresses subsequent growth,leading to suppression of short-wavelength perturbations.However,for long-wavelength perturbations,this suppression is weakened,resulting in increased instability in high-Z doped targets.The results are helpful for understanding the innerinterface-initiated instability and the influence of high-Z dopant on it,providing valuable insights for target design and instability control in ICF.展开更多
As a lightweight nanomaterial,Polyhedral Oligomeric Silsesquioxane(POSS)is widely applied to ablation resistance modification of Ethylene-Propylene-Dine Monomer(EPDM)insulation layer in aerospace propulsion thermal pr...As a lightweight nanomaterial,Polyhedral Oligomeric Silsesquioxane(POSS)is widely applied to ablation resistance modification of Ethylene-Propylene-Dine Monomer(EPDM)insulation layer in aerospace propulsion thermal protection system.However,various structures of POSS can form different crosslinked structures within the EPDM,which can affect the insulation layer properties.Various functionality POSS,Mono-Norbornene POSS(MN-POSS)and TriNorbornene POSS(TN-POSS),were designed and synthesized to obtain crosslinked-modified EPDMs with enhanced mechanical properties and ablation resistance simultaneously,and the relationship between POSS functionality,the mechanical properties,ablation resistance,heat-shielding and thermal decomposition of EPDM/Aramid Fiber(AF)composites were explored comprehensively.MN-POSS and TN-POSS increased the tensile strength of EPDM composites by 25.3%and 75.2%respectively,reduced the linear ablation rate by 37.7%and 33.7%respectively,and reduced the back temperatures by 3.9°C and 3.3°C respectively.Under conditions of equal cage structure(T8),the suspended crosslinked structure caused by MN-POSS exhibited better ablation resistance and heat-shielding performance as well as thermal decomposition,and the anchored crosslinked structure caused by TN-POSS exhibited better tensile strength.The structural transformation indicates that the POSS nanocages can be transformed into a ceramic structure in cruel environments to resist the erosion of heat flow and enhance the ablation resistance of insulation layer.展开更多
文摘1.Introduction to ablative TPS The Mars 2020 mission underscored the critical role of ablative Thermal Protection Systems(TPS)during atmospheric entry,where spacecraft encounter extreme aerodynamic heating.Established in the mid-20th century,blunt body theories led to the creation of ablative heat shields that effectively manage thermal loads through thermo-chemo-mechanical decomposition.This paper revisits the development and application of ablative TPS materials,which are single-mission solutions capable of withstanding entry velocities surpassing 10 km/s.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.12074399,12204500,and 12004403)the Key Projects of the Intergovernmental International Scientifi and Technological Innovation Cooperation(Grant No.2021YFE0116700)+1 种基金the Shanghai Natural Science Foundation(Grant No.20ZR1464400)the Shanghai Sailing Program(Grant No.22YF1455300)。
文摘The effect of drive laser wavelength on the growth of ablative Rayleigh–Taylor instability(ARTI)in inertial confinemen fusion(ICF)is studied with two-dimensional numerical simulations.The results show that in the plasma acceleration phase,shorter wavelengths lead to more efficien coupling between the laser and the kinetic energy of the implosion fluid Under the condition that the laser energy coupled to the implosion flui is constant,the ARTI growth rate decreases as the laser wavelength moves toward the extreme ultraviolet band,reaching its minimum value near λ=65 nm,and when the laser wavelength continuously moves toward the X-ray band,the ARTI growth rate increases rapidly.It is found that the results deviate from the theoretical ARTI growth rate.As the laser intensity benchmark increases,the position of the minimum ARTI growth rate shifts toward shorter wavelengths.As the initial sinusoidal perturbation wavenumber decreases,the position of the minimum ARTI growth rate shifts toward longer wavelengths.We believe that the conclusions drawn from the present simulations and analysis will help provide a better understanding of the ICF process and improve the theory of ARTI growth.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Science(Grant Nos.XDA25050200 and XDA25010100)the National Natural Science Foundation of China(Grant Nos.12175309,12475252,and 12275356)+2 种基金the Defense Industrial Technology Development Program(Grant No.JCKYS2023212807)the Natural Science Foundation of Hunan Province,China(Grant No.2025JJ20007)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(Grant No.CX20230005).
文摘In the direct drive inertial confinement fusion(ICF)scheme,a rippled interface between the ablator and the deuterium–tritium ice fuel can feed out and form perturbation seeds for the ablative Rayleigh–Taylor instability,with undesirable effects.However,the evolution of this instability remains insufficiently studied,and the effects of high-Z dopant on this instability remain unclear.In this paper,we develop a theoretical model to calculate the feedout seeds and describe this instability.Our theory suggests that the feedout seeds are determined by the ablation pressure and the adiabatic index,while the subsequent growth depends mainly on the ablation velocity.Two-dimensional radiation hydrodynamic simulations confirm our theory.It is shown that targets with high-Z dopant in the outer ablator exhibit more severe feedout seeds,because of their higher ionization compared with undoped targets.The X-ray pre-ablation in high-Z doped targets significantly suppresses subsequent growth,leading to suppression of short-wavelength perturbations.However,for long-wavelength perturbations,this suppression is weakened,resulting in increased instability in high-Z doped targets.The results are helpful for understanding the innerinterface-initiated instability and the influence of high-Z dopant on it,providing valuable insights for target design and instability control in ICF.
基金the support from the Xianyang Major Scientific and Technological Innovation Special Project—University and Research Institute“Three-Item Reform”Technology Transfer Project,China(No.D5140240003)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2023093)。
文摘As a lightweight nanomaterial,Polyhedral Oligomeric Silsesquioxane(POSS)is widely applied to ablation resistance modification of Ethylene-Propylene-Dine Monomer(EPDM)insulation layer in aerospace propulsion thermal protection system.However,various structures of POSS can form different crosslinked structures within the EPDM,which can affect the insulation layer properties.Various functionality POSS,Mono-Norbornene POSS(MN-POSS)and TriNorbornene POSS(TN-POSS),were designed and synthesized to obtain crosslinked-modified EPDMs with enhanced mechanical properties and ablation resistance simultaneously,and the relationship between POSS functionality,the mechanical properties,ablation resistance,heat-shielding and thermal decomposition of EPDM/Aramid Fiber(AF)composites were explored comprehensively.MN-POSS and TN-POSS increased the tensile strength of EPDM composites by 25.3%and 75.2%respectively,reduced the linear ablation rate by 37.7%and 33.7%respectively,and reduced the back temperatures by 3.9°C and 3.3°C respectively.Under conditions of equal cage structure(T8),the suspended crosslinked structure caused by MN-POSS exhibited better ablation resistance and heat-shielding performance as well as thermal decomposition,and the anchored crosslinked structure caused by TN-POSS exhibited better tensile strength.The structural transformation indicates that the POSS nanocages can be transformed into a ceramic structure in cruel environments to resist the erosion of heat flow and enhance the ablation resistance of insulation layer.
