In EAST long-pulsed discharge(hundreds of seconds),electric magnetic diagnosis(EMD)is very important,since EMD not only monitors tokamak security status but also provides accurate measurement accuracy for reconstructi...In EAST long-pulsed discharge(hundreds of seconds),electric magnetic diagnosis(EMD)is very important,since EMD not only monitors tokamak security status but also provides accurate measurement accuracy for reconstruction of the plasma boundary.To avoid current measurement drift,a fiber optic current sensor,based on the Faraday effect,is developed and used for poloidal and plasma current feedback control for the first time,relative current measurement accuracy is within 0.5%.To ensure plasma boundary control accuracy,a detailed set of magnetic measurement calibration methods is developed before the plasma discharge.The maximum relative error is less than 1%,the corresponding control accuracy is within 1 cm.To minimize integrator drift error,a long-pulse integrator test is essential,the corresponding drift error needs to be subtracted in plasma control system.Besides,the saddle coil and Mirnov coil not only help to detect MHD issues,but are also utilized for plasma disruption prediction during the long-pulse discharge.展开更多
When material dimensions are reduced to the nanoscale,exceptional physical mechanics properties can be obtained that differ significantly from the corresponding bulk materials.Here we review the physical mechanics of ...When material dimensions are reduced to the nanoscale,exceptional physical mechanics properties can be obtained that differ significantly from the corresponding bulk materials.Here we review the physical mechanics of the friction of low‐dimensional nanomaterials,including zero‐dimensional nanoparticles,one‐dimensional multiwalled nanotubes and nanowires,and two‐dimensional nanomaterials-such as graphene,hexagonal boron nitride(h‐BN),and transition‐metal dichalcogenides-as well as topological insulators.Nanoparticles between solid surfaces can serve as rolling and sliding lubrication,while the interlayer friction of multiwalled nanotubes can be ultralow or significantly high and sensitive to interwall spacing and chirality matching,as well as the tube materials.The interwall friction can be several orders of magnitude higher in binary polarized h‐BN tubes than in carbon nanotubes mainly because of wall buckling.Furthermore,current extensive studies on two‐dimensional nanomaterials are comprehensively reviewed herein.In contrast to their bulk materials that serve as traditional dry lubricants(e.g.,graphite,bulk h‐BN,and MoS_(2)),large‐area high‐quality monolayered two‐dimensional nanomaterials can serve as single‐atom‐thick coatings that minimize friction and wear.In addition,by appropriately tuning the surface properties,these materials have shown great promise for creating energy‐efficient self‐powered electro‐opto‐magneto‐mechanical nanosystems.State‐of‐the‐art experimental and theoretical methods to characterize friction in nanomaterials are also introduced.展开更多
Twin boundaries(TBs)in transition metal dichalcogenides(TMDs)constitute distinctive one dimensional electronic systems,exhibiting intriguing physical and chemical properties that have garnered significant attention in...Twin boundaries(TBs)in transition metal dichalcogenides(TMDs)constitute distinctive one dimensional electronic systems,exhibiting intriguing physical and chemical properties that have garnered significant attention in the fields of quantum physics and electrocatalysis.However,the controlled manipula-tion of TBs in terms of density and specific atomic configurations remains a fomidable challenge.In this study,we present a non-epitaxial growth approach that enables the controlled and large scale fabrication of homoge-neous catalytically active TBs in monolayer TMDs on arbitrary substrates.Notably,the density achieved using this strategy is six times higher than that observed in convention chemical vapor deposition(CVD)-grown sam-ples.Through rigorous experimental analysis and multigrain Wulff construc tion simulations,we elucidate theroleof regulating themetal source diffusion process,which serves as the key factor for inducing the self-oriented growth ofTMD grains and the formation of unified TBs.Furthermore,we demonstrate that this novel growth mode can be readily incorporated into the conventional CVD growth method by making a simple modification of the growth tempera-ture profle,thereby offering a universal approach for engineering of grain boundaries in two-dimensional materials.展开更多
基金supported by the National Magnetic Confinement Fusion Program of China(Nos.2018YFE0302100 and 2022YFE03010002)National Natural Science Foundation of China(Nos.12205195)。
文摘In EAST long-pulsed discharge(hundreds of seconds),electric magnetic diagnosis(EMD)is very important,since EMD not only monitors tokamak security status but also provides accurate measurement accuracy for reconstruction of the plasma boundary.To avoid current measurement drift,a fiber optic current sensor,based on the Faraday effect,is developed and used for poloidal and plasma current feedback control for the first time,relative current measurement accuracy is within 0.5%.To ensure plasma boundary control accuracy,a detailed set of magnetic measurement calibration methods is developed before the plasma discharge.The maximum relative error is less than 1%,the corresponding control accuracy is within 1 cm.To minimize integrator drift error,a long-pulse integrator test is essential,the corresponding drift error needs to be subtracted in plasma control system.Besides,the saddle coil and Mirnov coil not only help to detect MHD issues,but are also utilized for plasma disruption prediction during the long-pulse discharge.
基金This work was supported by The National Key Basic Research and Development(973)Program of China(2013CB932604 and 2012CB933403)The National Natural Science Foundation of China(Nos.51472117,11072109,11472131)+3 种基金the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(0414K01,0413G01,0413Y02)the Jiangsu NSF(BK20131356,BK20130781)the Fundamental Research Funds for the Central Universities of China(No.NE2012005)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘When material dimensions are reduced to the nanoscale,exceptional physical mechanics properties can be obtained that differ significantly from the corresponding bulk materials.Here we review the physical mechanics of the friction of low‐dimensional nanomaterials,including zero‐dimensional nanoparticles,one‐dimensional multiwalled nanotubes and nanowires,and two‐dimensional nanomaterials-such as graphene,hexagonal boron nitride(h‐BN),and transition‐metal dichalcogenides-as well as topological insulators.Nanoparticles between solid surfaces can serve as rolling and sliding lubrication,while the interlayer friction of multiwalled nanotubes can be ultralow or significantly high and sensitive to interwall spacing and chirality matching,as well as the tube materials.The interwall friction can be several orders of magnitude higher in binary polarized h‐BN tubes than in carbon nanotubes mainly because of wall buckling.Furthermore,current extensive studies on two‐dimensional nanomaterials are comprehensively reviewed herein.In contrast to their bulk materials that serve as traditional dry lubricants(e.g.,graphite,bulk h‐BN,and MoS_(2)),large‐area high‐quality monolayered two‐dimensional nanomaterials can serve as single‐atom‐thick coatings that minimize friction and wear.In addition,by appropriately tuning the surface properties,these materials have shown great promise for creating energy‐efficient self‐powered electro‐opto‐magneto‐mechanical nanosystems.State‐of‐the‐art experimental and theoretical methods to characterize friction in nanomaterials are also introduced.
基金National Key R&D Program of China(2018YFA0305800)Natural Science Foundation of China(51872285)+6 种基金Beijing Outstanding Young Scientist Program(BJJWZYJ H01201914430039)CAS Project for Young Scientists in Basic Research(YSBR-003)Fundamental Research Funds for the Central UniversitiesNational Key R&D Program of China(2019YFA0705400)Natural Science Foundation of China(1221101035,12225205,22073048)computations were in part performed at the High-performance Computational Center at NUAASingapore Ministry of Education AcRF Tier 2(MOE2019-T2-2-105 and MOE-MOET2EP101210006)and AcRF Tier 1(RG7/21).
文摘Twin boundaries(TBs)in transition metal dichalcogenides(TMDs)constitute distinctive one dimensional electronic systems,exhibiting intriguing physical and chemical properties that have garnered significant attention in the fields of quantum physics and electrocatalysis.However,the controlled manipula-tion of TBs in terms of density and specific atomic configurations remains a fomidable challenge.In this study,we present a non-epitaxial growth approach that enables the controlled and large scale fabrication of homoge-neous catalytically active TBs in monolayer TMDs on arbitrary substrates.Notably,the density achieved using this strategy is six times higher than that observed in convention chemical vapor deposition(CVD)-grown sam-ples.Through rigorous experimental analysis and multigrain Wulff construc tion simulations,we elucidate theroleof regulating themetal source diffusion process,which serves as the key factor for inducing the self-oriented growth ofTMD grains and the formation of unified TBs.Furthermore,we demonstrate that this novel growth mode can be readily incorporated into the conventional CVD growth method by making a simple modification of the growth tempera-ture profle,thereby offering a universal approach for engineering of grain boundaries in two-dimensional materials.
