The ion thruster is an engine with high specific impulse for satellites and spacecrafts,which uses electric energy to boost the spacecraft.The ion optical system,also known as gate assemblies which consist of accelera...The ion thruster is an engine with high specific impulse for satellites and spacecrafts,which uses electric energy to boost the spacecraft.The ion optical system,also known as gate assemblies which consist of acceleration and screen grids,is the key component of the ion thruster.In this paper,the static mechanical properties of the C/C composite grids are evaluated based on the structural design.Representative volume element (RVE) is adopted to simplify the braded composite structure as a continuum material.The dynamical behavior of the 100 mm ion thruster optics in the launch environment (1000g shock-load) is numerically modeled and simulated with the half-sine pulse method.The impact response of the C/C and molybdenum gate assemblies on the stress distribution and deformation is investigated.The simulated results indicate that the magnitudes of the normal displacement of the composite grids subject to the uniformly distributed load are on the same level as molybdenum grids although the normal stiffness of the composite grids is much smaller.When subject to impact loading,the stress distribution in the C/C composite grids is similar to molybdenum grids while the stress magnitude is much smaller.This finding shows that the C/C gate assemblies outperform molybdenum grids and meet the requirement of long lifetime service in space travel.展开更多
Ag@Ag-Pdx core-shell nanocomposites with various Ag/Pd ratio were deposited on Ag nanoplates using a seed growth method.When physically loaded on C3N4,Ag@Ag-Pd0.077/C3N4 with optimized Ag/Pd ratio could accomplish hig...Ag@Ag-Pdx core-shell nanocomposites with various Ag/Pd ratio were deposited on Ag nanoplates using a seed growth method.When physically loaded on C3N4,Ag@Ag-Pd0.077/C3N4 with optimized Ag/Pd ratio could accomplish high catalytic performance for the semi-hydrogenation of phenylacetylene as well as other aliphatic(both terminal and internal alkynes)alkynes and phenylcycloalkynes containing functional groups(such as ester,hydroxyl,ethyl groups)under room temperature and 1 atm H_(2).The alloying and ensemble effects are used to interpret such catalytic performance.展开更多
基金Project supported by the National Key R&D Program of China(No.2018YFF01014200)the National Natural Science Foundation of China(Nos.11727804,11672347,and 51732008)
文摘The ion thruster is an engine with high specific impulse for satellites and spacecrafts,which uses electric energy to boost the spacecraft.The ion optical system,also known as gate assemblies which consist of acceleration and screen grids,is the key component of the ion thruster.In this paper,the static mechanical properties of the C/C composite grids are evaluated based on the structural design.Representative volume element (RVE) is adopted to simplify the braded composite structure as a continuum material.The dynamical behavior of the 100 mm ion thruster optics in the launch environment (1000g shock-load) is numerically modeled and simulated with the half-sine pulse method.The impact response of the C/C and molybdenum gate assemblies on the stress distribution and deformation is investigated.The simulated results indicate that the magnitudes of the normal displacement of the composite grids subject to the uniformly distributed load are on the same level as molybdenum grids although the normal stiffness of the composite grids is much smaller.When subject to impact loading,the stress distribution in the C/C composite grids is similar to molybdenum grids while the stress magnitude is much smaller.This finding shows that the C/C gate assemblies outperform molybdenum grids and meet the requirement of long lifetime service in space travel.
基金This work was financially supported by the National Key R&D Program of China(2017YFA0700104)the National Natural Science Foundation of China(21911530255)the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(2019-6).
文摘Ag@Ag-Pdx core-shell nanocomposites with various Ag/Pd ratio were deposited on Ag nanoplates using a seed growth method.When physically loaded on C3N4,Ag@Ag-Pd0.077/C3N4 with optimized Ag/Pd ratio could accomplish high catalytic performance for the semi-hydrogenation of phenylacetylene as well as other aliphatic(both terminal and internal alkynes)alkynes and phenylcycloalkynes containing functional groups(such as ester,hydroxyl,ethyl groups)under room temperature and 1 atm H_(2).The alloying and ensemble effects are used to interpret such catalytic performance.
