We present a novel scheme for dense electron acceleration driven by the laser irradiation of a near-critical-density plasma.The electron reflux effect in a transversely tailored plasma is particularly enhanced in the ...We present a novel scheme for dense electron acceleration driven by the laser irradiation of a near-critical-density plasma.The electron reflux effect in a transversely tailored plasma is particularly enhanced in the area of peak density.We observe a bubble-like distribution of re-injected electrons,which forms a strong quasistatic electromagnetic field that can accelerate electrons longitudinally while also preserving the electron transverse emittance.Simulation results demonstrate that over-dense electrons could be trapped in such an artificial bubble and accelerated to an energy of ~500 MeV.The obtained relativistic electron beam can reach a total charge of up to 0.26 nC and is well collimated with a small divergence of 17 mrad.Moreover,the wavelength of electron oscillation is noticeably reduced due to the shaking of the bubble structure in the laser field.As a result,the energy of the produced photons is substantially increased to the range.This new regime provides a path to generating high-charge electron beams and high-energy-ray sources.展开更多
Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus.The samples,having same dry density with different water content ratio,were prepared.Two...Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus.The samples,having same dry density with different water content ratio,were prepared.Two types of concrete with different surface roughness,i.e.,relatively smooth and relatively rough surface roughness,were also prepared.The main objectives of this paper are to show the effect of water content,normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface.The following were concluded in this study:1)the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16%for the case of rough concrete surface where the shear failure occurs in the body of the clay sample;2)the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface;3)two types of interface failure mechanism may change each other with different water content ratio;4)the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.展开更多
In this paper,a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface(CCCI)based on the principle of transition mechanism failure(TMF).A number of simple shear tests were ...In this paper,a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface(CCCI)based on the principle of transition mechanism failure(TMF).A number of simple shear tests were conducted on CCCI to demonstrate different failure mechanisms;i.e.,sliding failure and deformation failure.The clay soil used in the test was collected from the"Shuang Jang Kou"earth rockfill dam project.It was found that the behavior of the interface depends on the critical water contents by which two failure mechanisms can be recognized.Mathematical relations were proposed between the shear at failure and water content in addition to the transition mechanism indicator.The mathematical relations were then incorporated into the interface model.The performance of the model is verified with the experimental results.The verification shows that the proposed model is capable of predicting the interface shear stress versus the total shear displacement very well.展开更多
基金supported by the China Postdoctoral Science Foundation(Grant No.2021M692204)the National Natural Science Foundation of China(Grant No.11805278)+3 种基金the Fundamental Research Program of Shenzhen(Grant No.SZWD2021007)the Science and Technology on Plasma Physics Laboratorythe Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010326)the Shenzhen Technology University.
文摘We present a novel scheme for dense electron acceleration driven by the laser irradiation of a near-critical-density plasma.The electron reflux effect in a transversely tailored plasma is particularly enhanced in the area of peak density.We observe a bubble-like distribution of re-injected electrons,which forms a strong quasistatic electromagnetic field that can accelerate electrons longitudinally while also preserving the electron transverse emittance.Simulation results demonstrate that over-dense electrons could be trapped in such an artificial bubble and accelerated to an energy of ~500 MeV.The obtained relativistic electron beam can reach a total charge of up to 0.26 nC and is well collimated with a small divergence of 17 mrad.Moreover,the wavelength of electron oscillation is noticeably reduced due to the shaking of the bubble structure in the laser field.As a result,the energy of the produced photons is substantially increased to the range.This new regime provides a path to generating high-charge electron beams and high-energy-ray sources.
基金supported by the China Scholarship Council(No.2006368T15)the National Nature Science Foundation of China(Grant No.50639050)。
文摘Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus.The samples,having same dry density with different water content ratio,were prepared.Two types of concrete with different surface roughness,i.e.,relatively smooth and relatively rough surface roughness,were also prepared.The main objectives of this paper are to show the effect of water content,normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface.The following were concluded in this study:1)the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16%for the case of rough concrete surface where the shear failure occurs in the body of the clay sample;2)the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface;3)two types of interface failure mechanism may change each other with different water content ratio;4)the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.
基金This study was achieved under the support of China Scholarship Council(CSC)(Grant No.2006368T15)Financial support from the project“Test study on the properties of coarse-grained soils for high earth rockfill dam under high and complex stress conditions”(Grant No.50639050)from NSFC
文摘In this paper,a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface(CCCI)based on the principle of transition mechanism failure(TMF).A number of simple shear tests were conducted on CCCI to demonstrate different failure mechanisms;i.e.,sliding failure and deformation failure.The clay soil used in the test was collected from the"Shuang Jang Kou"earth rockfill dam project.It was found that the behavior of the interface depends on the critical water contents by which two failure mechanisms can be recognized.Mathematical relations were proposed between the shear at failure and water content in addition to the transition mechanism indicator.The mathematical relations were then incorporated into the interface model.The performance of the model is verified with the experimental results.The verification shows that the proposed model is capable of predicting the interface shear stress versus the total shear displacement very well.
