In the past few decades,ion engines have been widely used in deep-space propulsion and satellite station-keeping.The aim of extending the thruster lifetime is still one of the most important parts during the design st...In the past few decades,ion engines have been widely used in deep-space propulsion and satellite station-keeping.The aim of extending the thruster lifetime is still one of the most important parts during the design stage of ion engine.As one of the core components of ion engine,the grid assembly of ion optic systems may experience long-term ion sputtering in extreme electro-thermal environments,which will eventually lead to its structural and electron-backstreaming failures.In this paper,the current studies of the grid assembly erosion process are systematically analyzed from the aspects of sputtering damage process of grid materials,numerical simulations,and measurements of erosion characteristics of grid assembly.The advantages and disadvantages of various erosion prediction models are highlighted,and the key factors and processes affecting the prediction accuracy of grid assembly erosion patterns are analyzed.Three different types of experimental methods of grid assembly erosion patterns are compared.The analysis in this paper is of great importance for selecting the sputter-resistant grid materials,as well as establishing the erosion models and measurement methods to accurately determine the erosion rate and failure modes of grid assembly.Consequently,the working conditions and structure parameters of ion optic systems could be optimized based on erosion models to promote the ion engine lifetime.展开更多
Low-Z materials, such as carbon-based materials and Be, are major plasma-facing material (PFM) for current, even in future fusion devices. In this paper, a new type of multielement-doped carbon-based materials develop...Low-Z materials, such as carbon-based materials and Be, are major plasma-facing material (PFM) for current, even in future fusion devices. In this paper, a new type of multielement-doped carbon-based materials developed are presented along with experimental re-sults of their properties. The results indicate a decrease in chemical sputtering yield by one order of magnitude, a decrease in both thermal shock resistance and radiation-enhanced sublimation, an evidently lower temperature desorption spectrum, and combined properties of exposing to plasma.展开更多
In order to study the effect of the microstructure with Al and V added TiN coatings, TiN, TiAlN and TiAlVN coatings were deposited on AISI M2 high-speed steels by magnetron reactive sputtering. The microstructures of ...In order to study the effect of the microstructure with Al and V added TiN coatings, TiN, TiAlN and TiAlVN coatings were deposited on AISI M2 high-speed steels by magnetron reactive sputtering. The microstructures of all the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate that the addition of Al into TiN coatings reduces their lattice constant, but a further addition of V into TiAlN coatings increases their lattice constant. Moreover, the growth morphologies for TiN, TiAlN, and TiAlVN indicate that adding Al and V has a tendency to improve the columnar structure. The (111) and (200) orientations of TiN, TiAlN, and TiAlVN are identified. Theε(Fe3N-Fe2N) phase occurs because a small amount of Fe is present in the coatings. The interlayers of TiAlN and TiAlVN have the preferred (01 1 0) orientation. The texture (columnar) structure of the (111) and (200) orientations is observed in the TiAlN and TiAlVN coatings. An orientation relationship of (01 1 0)α-Ti//(110)T.M occurs between the interlayer and tempered martensite (T.M) in TiAlVN.展开更多
In this paper a numerical simulation of a planar DC magnetron discharge is performed with the Particle-in Cell/Monte Carlo Collision （PIC/MCC） method. The magnetic field used in the simulation is calculated with fin...In this paper a numerical simulation of a planar DC magnetron discharge is performed with the Particle-in Cell/Monte Carlo Collision （PIC/MCC） method. The magnetic field used in the simulation is calculated with finite element method according to experimental configuration. The simulation is carried out under the condition of gas pressure of 0.665 Pa and voltage magnitude of 400V. Typical results such as the potential distribution, charged particle densities, the discharge current density and ion flux onto the target are calculated. The erosion profile from the simulation is compared with the experimental data. The maximum erosion position corresponds to the place where the magnetic field lines are parallel to the target surface.展开更多
Low activation materials have to be developed toward fusion demonstrationreactors. Ferritic steel, vanadium alloy and SiC/SiC composite are candidate materials of the firstwall, vacuum vessel and blanket components, r...Low activation materials have to be developed toward fusion demonstrationreactors. Ferritic steel, vanadium alloy and SiC/SiC composite are candidate materials of the firstwall, vacuum vessel and blanket components, respectively. Although changes of mechanical-thermalproperties owing to neutron irradiation have been investigated so far, there is little data for theplasma material interactions, such as fuel hydrogen retention and erosion. In the present study,deuterium retention and physical sputtering of low activation ferritic steel, F82H, wereinvestigated by using deuterium ion irradiation apparatus. After a ferritic steel sample wasirradiated by 1.7 keV D^+ ions, the weight loss was measured to obtain the physical sputteringyield. The sputtering yield was 0.04, comparable to that of stainless steel. In order to obtain theretained amount of deuterium, technique of thermal desorption spectroscopy (TDS) was employed to theirradiated sample. The retained deuterium desorbed at temperature ranging from 450 K to 700 K, inthe forms of DHO, D_2, D_2O and hydrocarbons. Hence, the deuterium retained can be reduced by bakingwith a relatively low temperature. The fluence dependence of retained amount of deuterium wasmeasured by changing the ion fluence. In the ferritic steel without mechanical polish, the retainedamount was large even when the fluence was low. In such a case, a large amount of deuterium wastrapped in the surface oxide layer containing O and C. When the fluence was large, the thickness ofsurface oxide layer was reduced by the ion sputtering, and then the retained amount in the oxidelayer decreased. In the case of a high fluence, the retained amount of deuterium became comparableto that of ferritic steel with mechanical polish or SS 316 L, and one order of magnitude smallerthan that of graphite. When the ferritic steel is used, it is required to remove the surface oxidelayer for reduction of fuel hydrogen retention. Ferritic steel sample was exposed to the environmentof JFT-2M tokamak in JAERI and after thatthe deuterium retention was examined. The result wasroughly the same as the case of deuterium ion irradiation experiment.展开更多
基金co-supported by the National Key R&D Program of China(No.2022YFB3403500)the National Natural Science Foundation of China(No.NSFC52202460)the China Postdoctoral Science Foundation(Nos.2021M690392,2021TQ0036,and 2023TQ0031)。
文摘In the past few decades,ion engines have been widely used in deep-space propulsion and satellite station-keeping.The aim of extending the thruster lifetime is still one of the most important parts during the design stage of ion engine.As one of the core components of ion engine,the grid assembly of ion optic systems may experience long-term ion sputtering in extreme electro-thermal environments,which will eventually lead to its structural and electron-backstreaming failures.In this paper,the current studies of the grid assembly erosion process are systematically analyzed from the aspects of sputtering damage process of grid materials,numerical simulations,and measurements of erosion characteristics of grid assembly.The advantages and disadvantages of various erosion prediction models are highlighted,and the key factors and processes affecting the prediction accuracy of grid assembly erosion patterns are analyzed.Three different types of experimental methods of grid assembly erosion patterns are compared.The analysis in this paper is of great importance for selecting the sputter-resistant grid materials,as well as establishing the erosion models and measurement methods to accurately determine the erosion rate and failure modes of grid assembly.Consequently,the working conditions and structure parameters of ion optic systems could be optimized based on erosion models to promote the ion engine lifetime.
基金The work was supported by the National Nature Science Foundation of China No.19789503.
文摘Low-Z materials, such as carbon-based materials and Be, are major plasma-facing material (PFM) for current, even in future fusion devices. In this paper, a new type of multielement-doped carbon-based materials developed are presented along with experimental re-sults of their properties. The results indicate a decrease in chemical sputtering yield by one order of magnitude, a decrease in both thermal shock resistance and radiation-enhanced sublimation, an evidently lower temperature desorption spectrum, and combined properties of exposing to plasma.
文摘In order to study the effect of the microstructure with Al and V added TiN coatings, TiN, TiAlN and TiAlVN coatings were deposited on AISI M2 high-speed steels by magnetron reactive sputtering. The microstructures of all the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate that the addition of Al into TiN coatings reduces their lattice constant, but a further addition of V into TiAlN coatings increases their lattice constant. Moreover, the growth morphologies for TiN, TiAlN, and TiAlVN indicate that adding Al and V has a tendency to improve the columnar structure. The (111) and (200) orientations of TiN, TiAlN, and TiAlVN are identified. Theε(Fe3N-Fe2N) phase occurs because a small amount of Fe is present in the coatings. The interlayers of TiAlN and TiAlVN have the preferred (01 1 0) orientation. The texture (columnar) structure of the (111) and (200) orientations is observed in the TiAlN and TiAlVN coatings. An orientation relationship of (01 1 0)α-Ti//(110)T.M occurs between the interlayer and tempered martensite (T.M) in TiAlVN.
基金Project supported by the National Science Found for Distinguished Young Scholars of China (Grant No 50407015)
文摘In this paper a numerical simulation of a planar DC magnetron discharge is performed with the Particle-in Cell/Monte Carlo Collision （PIC/MCC） method. The magnetic field used in the simulation is calculated with finite element method according to experimental configuration. The simulation is carried out under the condition of gas pressure of 0.665 Pa and voltage magnitude of 400V. Typical results such as the potential distribution, charged particle densities, the discharge current density and ion flux onto the target are calculated. The erosion profile from the simulation is compared with the experimental data. The maximum erosion position corresponds to the place where the magnetic field lines are parallel to the target surface.
文摘Low activation materials have to be developed toward fusion demonstrationreactors. Ferritic steel, vanadium alloy and SiC/SiC composite are candidate materials of the firstwall, vacuum vessel and blanket components, respectively. Although changes of mechanical-thermalproperties owing to neutron irradiation have been investigated so far, there is little data for theplasma material interactions, such as fuel hydrogen retention and erosion. In the present study,deuterium retention and physical sputtering of low activation ferritic steel, F82H, wereinvestigated by using deuterium ion irradiation apparatus. After a ferritic steel sample wasirradiated by 1.7 keV D^+ ions, the weight loss was measured to obtain the physical sputteringyield. The sputtering yield was 0.04, comparable to that of stainless steel. In order to obtain theretained amount of deuterium, technique of thermal desorption spectroscopy (TDS) was employed to theirradiated sample. The retained deuterium desorbed at temperature ranging from 450 K to 700 K, inthe forms of DHO, D_2, D_2O and hydrocarbons. Hence, the deuterium retained can be reduced by bakingwith a relatively low temperature. The fluence dependence of retained amount of deuterium wasmeasured by changing the ion fluence. In the ferritic steel without mechanical polish, the retainedamount was large even when the fluence was low. In such a case, a large amount of deuterium wastrapped in the surface oxide layer containing O and C. When the fluence was large, the thickness ofsurface oxide layer was reduced by the ion sputtering, and then the retained amount in the oxidelayer decreased. In the case of a high fluence, the retained amount of deuterium became comparableto that of ferritic steel with mechanical polish or SS 316 L, and one order of magnitude smallerthan that of graphite. When the ferritic steel is used, it is required to remove the surface oxidelayer for reduction of fuel hydrogen retention. Ferritic steel sample was exposed to the environmentof JFT-2M tokamak in JAERI and after thatthe deuterium retention was examined. The result wasroughly the same as the case of deuterium ion irradiation experiment.
