An ionic liquid ion source(ILIS)is a kind of high brightness ion source capable of providing high-speed positive or negative ion beams.This paper presents a miniaturized ILIS based on an array of porous metal strips.T...An ionic liquid ion source(ILIS)is a kind of high brightness ion source capable of providing high-speed positive or negative ion beams.This paper presents a miniaturized ILIS based on an array of porous metal strips.The porous emitter array,integrated with seven 10 mm long strips,is fabricated using wire electrical discharge machining(WEDM)combined with electrochemical etching.The assembled ILIS is 30 mm×30 mm×17.5 mm in size and weighs less than 25 g.A series of experiments,including anⅠ-Ⅴcharacteristic test,a retarding potential analyzer(RPA)test,and a spatial plume distribution test,have been conducted in vacuo to characterize the performance of the ILIS.Results show that the emitted current is up to about 800μA and ion transparency is as high as 94%.Besides,RPA curves reveal that the total fragmentation rate of the emitted particles accounts for 48.8%in positive mode and 59.8%in negative mode.Further,with the increase in applied acceleration voltage,the voltage loss rises while the energy efficiency decreases.It is also found that the plume perpendicular to the strips has a higher divergence than the one parallel to the strips.A numerical simulation by COMSOL reveals that the electric field distribution between the two electrodes results in such a spatial plume profile.展开更多
Though tremendous efforts have been made to investigate electrospray,some aspects,such as the evolution of the menisci on the micropores of porous emitter tips and the transient response of the meniscus during the pol...Though tremendous efforts have been made to investigate electrospray,some aspects,such as the evolution of the menisci on the micropores of porous emitter tips and the transient response of the meniscus during the polarity alternation,need to be further understood.This paper presents a computation fluid dynamics(CFD)model to describe the meniscus formation in the ionic liquid electrospray process.The CFD model,based on the Taylor–Melcher leaky dielectric fluid theory and the volume of fluid(VOF)method,is validated by experiments.The evolution of the meniscus on the basis of a micropore is presented using two typical ionic liquids,EMI-BF_(4) and EMI-Im.The influences of the pore size,flow rate and applied voltage on the formation of the meniscus have been studied.Results show that a larger pore is more likely to start emission,and the time consumed for liquid meniscus formation decreases with increasing applied voltage and flow rate.Further,it is found that alternation of polarity does not destroy the structure of the meniscus but retards the formation process,and a faster polarity alteration leads to a shorter delay in meniscus formation time.展开更多
Aims Pigment composition is an important functional trait that can be affected by environmental factors.the objective of this study was to investigate the effect of soil salinity on pigment composition in Suaeda salsa...Aims Pigment composition is an important functional trait that can be affected by environmental factors.the objective of this study was to investigate the effect of soil salinity on pigment composition in Suaeda salsa by comparing chlorophyll and betacyanin content in the Liaohe estuary wetland,a typical coastal wetland in northeast China.Methods We investigated the plant biomass,percentage of red leaves and pigment content(chlorophyll a,chlorophyll b and betacyanins)in S.salsa in intertidal and supratidal zones of the upper,middle and lower reaches of the Liaohe estuary wetlands.the Na^(+)content of both the soil and plant was also measured.Full analysis of variance and multivariate analysis were used to compare differences in pig-ment content and Na^(+)content between the supratidal and intertidal zones.Important Findings Pigment composition was significantly affected by soil salinity.With increasing soil salinity,the percentage of red leaves was higher in the intertidal zone than in the supratidal zone.In all three reaches,plants had lower chlorophyll a content and higher betacyanin con-tent in the intertidal zone than in the supratidal zone.Compared to chlorophyll a,chlorophyll b was less sensitive to soil salinity.there were no differences in chlorophyll b content between the intertidal and supratidal zones in the upper and lower reaches.Furthermore,pigment composition was associated with both the plant tissue and soil Na^(+)content.Compared to the supratidal zone,the intertidal zone had a higher Na^(+)content in plants.there was a negative rela-tionship between plant chlorophyll content and soil Na^(+)content,but a positive relationship between betacyanin content and soil Na^(+)content.Overall,the results indicated that there might be a trade-off between leaf chlorophyll and betacyanin content in S.salsa to main-tain its growth and survival in high salinity environments.展开更多
基金supported by National Natural Science Foundation of China(No.52075334)。
文摘An ionic liquid ion source(ILIS)is a kind of high brightness ion source capable of providing high-speed positive or negative ion beams.This paper presents a miniaturized ILIS based on an array of porous metal strips.The porous emitter array,integrated with seven 10 mm long strips,is fabricated using wire electrical discharge machining(WEDM)combined with electrochemical etching.The assembled ILIS is 30 mm×30 mm×17.5 mm in size and weighs less than 25 g.A series of experiments,including anⅠ-Ⅴcharacteristic test,a retarding potential analyzer(RPA)test,and a spatial plume distribution test,have been conducted in vacuo to characterize the performance of the ILIS.Results show that the emitted current is up to about 800μA and ion transparency is as high as 94%.Besides,RPA curves reveal that the total fragmentation rate of the emitted particles accounts for 48.8%in positive mode and 59.8%in negative mode.Further,with the increase in applied acceleration voltage,the voltage loss rises while the energy efficiency decreases.It is also found that the plume perpendicular to the strips has a higher divergence than the one parallel to the strips.A numerical simulation by COMSOL reveals that the electric field distribution between the two electrodes results in such a spatial plume profile.
基金supported by National Natural Science Foundation of China(No.52075334)。
文摘Though tremendous efforts have been made to investigate electrospray,some aspects,such as the evolution of the menisci on the micropores of porous emitter tips and the transient response of the meniscus during the polarity alternation,need to be further understood.This paper presents a computation fluid dynamics(CFD)model to describe the meniscus formation in the ionic liquid electrospray process.The CFD model,based on the Taylor–Melcher leaky dielectric fluid theory and the volume of fluid(VOF)method,is validated by experiments.The evolution of the meniscus on the basis of a micropore is presented using two typical ionic liquids,EMI-BF_(4) and EMI-Im.The influences of the pore size,flow rate and applied voltage on the formation of the meniscus have been studied.Results show that a larger pore is more likely to start emission,and the time consumed for liquid meniscus formation decreases with increasing applied voltage and flow rate.Further,it is found that alternation of polarity does not destroy the structure of the meniscus but retards the formation process,and a faster polarity alteration leads to a shorter delay in meniscus formation time.
基金This study was supported by the Forestry Industry Research Special Funds for Public Welfare Project(201404305).
文摘Aims Pigment composition is an important functional trait that can be affected by environmental factors.the objective of this study was to investigate the effect of soil salinity on pigment composition in Suaeda salsa by comparing chlorophyll and betacyanin content in the Liaohe estuary wetland,a typical coastal wetland in northeast China.Methods We investigated the plant biomass,percentage of red leaves and pigment content(chlorophyll a,chlorophyll b and betacyanins)in S.salsa in intertidal and supratidal zones of the upper,middle and lower reaches of the Liaohe estuary wetlands.the Na^(+)content of both the soil and plant was also measured.Full analysis of variance and multivariate analysis were used to compare differences in pig-ment content and Na^(+)content between the supratidal and intertidal zones.Important Findings Pigment composition was significantly affected by soil salinity.With increasing soil salinity,the percentage of red leaves was higher in the intertidal zone than in the supratidal zone.In all three reaches,plants had lower chlorophyll a content and higher betacyanin con-tent in the intertidal zone than in the supratidal zone.Compared to chlorophyll a,chlorophyll b was less sensitive to soil salinity.there were no differences in chlorophyll b content between the intertidal and supratidal zones in the upper and lower reaches.Furthermore,pigment composition was associated with both the plant tissue and soil Na^(+)content.Compared to the supratidal zone,the intertidal zone had a higher Na^(+)content in plants.there was a negative rela-tionship between plant chlorophyll content and soil Na^(+)content,but a positive relationship between betacyanin content and soil Na^(+)content.Overall,the results indicated that there might be a trade-off between leaf chlorophyll and betacyanin content in S.salsa to main-tain its growth and survival in high salinity environments.
