The enhanced performance of aerospace equipment drives parts development towards integration,complexity,and structural optimization.This advancement promotes metal near-net fabrication technologies like wire electrica...The enhanced performance of aerospace equipment drives parts development towards integration,complexity,and structural optimization.This advancement promotes metal near-net fabrication technologies like wire electrical discharge machining(WEDM)and 3D printing.However,the high initial surface roughness from WEDM or 3D printing poses significant challenges for the high-performance surface finishing required.To effectively reduce the surface roughness of the workpieces with high initial surface roughness,this paper proposes pulsed unipolar-polarisation plasma electrolytic polishing(PUP-PEP).The study examined the material removal mechanisms and surface polishing quality of PUP-PEP.This technique combines the high current density and material removal rate of the electrolytic polishing mode with the superior surface polishing quality of PEP through voltage waveform modulation.For an Inconel-718 superalloy part fabricated by WEDM,PUP-PEP reduced surface roughness from R_(a)7.39μm to R_(a)0.27μm in 6 min under optimal conditions.The roughness decreased from R_(a)7.39μm to R_(a)0.78μm in the first 3 min under pulsed unipolar-polarisation voltage,resulting in a remarkable 233%increase in efficiency compared to that with conventional PEP.Subsequently,the voltage output voltage is transformed into a constant voltage mode,and PEP is continued based on PUP-PEP to finally reduce the workpiece surface roughness value to R_(a)0.27μm.The proposed PUP-PEP technology marks the implementation of‘polishing’instead of conventional rough-finish machining processes,presenting a new approach to the surface post-processing of metal near-net fabrication technologies.展开更多
The effects of linear falling ramp reset pulse related to addressing operation in an alternating current plasma display panel （AC PDP） were studied. The wall charge waveforms were measured by the electrode balance m...The effects of linear falling ramp reset pulse related to addressing operation in an alternating current plasma display panel （AC PDP） were studied. The wall charge waveforms were measured by the electrode balance method in a 12-inch coplanar AC PDP. The wall charge waveforms show the relationship between the slope ratio of the falling ramp reset pulse and the wall charges at the end of the falling ramp reset pulse which influences the addressing stability. Then the effects of the slope ratio of the linear falling ramp reset pulse on the addressing voltage and addressing time were investigated. The experimental results show that the minimum addressing voltage increases with the increase of the slope ratio of the falling ramp reset pulse, and so does the minimum addressing time. Based on the experimental results, the optimization of the addressing time and the slope ratio of the falling ramp pulse is discussed.展开更多
The high-voltage high-power press-packed IGBT(PPI)devices are the key component of the DC transmission apparatus.A PPI device is composed of several PPI submodules.In general,the PPI submodule works in a state of repe...The high-voltage high-power press-packed IGBT(PPI)devices are the key component of the DC transmission apparatus.A PPI device is composed of several PPI submodules.In general,the PPI submodule works in a state of repetitive turn-on and turn-off,and the corresponding working voltage is the positive periodic square waveform(PPSW)voltage,which is much different from the conventional AC or DC voltage.In addition,insulation capability is one of the most critical challenges in the design and fabrication of PPI devices.To improve the insulation capability of the device,composite insulation structures with multiple dielectrics are usually employed.Under the PPSW voltage,it is essential to analyze the transient electric field to solve the insulation challenge of the PPI devices.However,the electric field of the PPI is often calculated under the electrostatic field or DC field.Moreover,the transient characteristics of the electric field are ignored.Therefore,this paper focuses on the analysis of the transient characteristics of the electric field of the PPI submodule under the PPSW voltage.The influences of the waveform parameters of the PPSW voltage on the transient characteristics are demonstrated in detail.This study is significant for the insulation analysis and design of the PPIs.展开更多
A micro sensor chip of High-field Asymmetric Waveform Ion Mobility Spectrometry(FAIMS) was designed and fabricated by inductively coupled plasma(ICP) etching on the both sides of silicon and double silicon-glass bondi...A micro sensor chip of High-field Asymmetric Waveform Ion Mobility Spectrometry(FAIMS) was designed and fabricated by inductively coupled plasma(ICP) etching on the both sides of silicon and double silicon-glass bonding,with dimensions of 18.8 mm×12.4 mm×1.2mm.The sample ions were created at ambient pressure by VUV lamp ion source,which was equipped with a 10.6 eV photo discharge lamp(λ=116.5 nm).The 2-pentanone was adopted to illustrate the influences of high-field rectangular asymmetric waveform voltage amplitude,frequency and carrier gas flow rate on the performance of FAIMS sensor chip.The experiment results showed that with the frequency or carrier gas flow rate increasing,or voltage amplitude decreasing,the FAIMS sensitivity increases,and that the resolution decreases with the increasing of the frequency or flow rate.The FAIMS simulation results based on the SIMION software was in agreement with the experimental results.The FAIMS detection sensitivity experiment showed that the FAIMS sensor chip can detect positive and negative ions simultaneously,and has detection sensitivity as low as 0.1 ppm for acetic acid.展开更多
Dual harmonic systems have been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in a dual rf system...Dual harmonic systems have been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in a dual rf system, the potential well, the sub-buckets in the bunch and the multi-solutions of the phase equation are studied theoretically in this paper. Based on these theoretical studies, optimization of bunching factor and rf voltage waveform are made for the dual harmonic rf system in the upgrade phase of the China Spallation Neutron Source Rapid Cycling Synchrotron （CSNS/RCS）. In the optimization process, the simulation with space charge effect is done using a newly developed code. C-SCSIM.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.52205476)the Youth Talent Support Project of Jiangsu Provincial Association of Science and Technology(Grant No.TJ-2023-070)+1 种基金the Fund of Prospective Layout of Scientific Research for Nanjing University of Aeronautics and Astronautics(Grant No.1005-ILB23025-1A)the Fund of Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology(Grant No.1005-ZAA20003-14).
文摘The enhanced performance of aerospace equipment drives parts development towards integration,complexity,and structural optimization.This advancement promotes metal near-net fabrication technologies like wire electrical discharge machining(WEDM)and 3D printing.However,the high initial surface roughness from WEDM or 3D printing poses significant challenges for the high-performance surface finishing required.To effectively reduce the surface roughness of the workpieces with high initial surface roughness,this paper proposes pulsed unipolar-polarisation plasma electrolytic polishing(PUP-PEP).The study examined the material removal mechanisms and surface polishing quality of PUP-PEP.This technique combines the high current density and material removal rate of the electrolytic polishing mode with the superior surface polishing quality of PEP through voltage waveform modulation.For an Inconel-718 superalloy part fabricated by WEDM,PUP-PEP reduced surface roughness from R_(a)7.39μm to R_(a)0.27μm in 6 min under optimal conditions.The roughness decreased from R_(a)7.39μm to R_(a)0.78μm in the first 3 min under pulsed unipolar-polarisation voltage,resulting in a remarkable 233%increase in efficiency compared to that with conventional PEP.Subsequently,the voltage output voltage is transformed into a constant voltage mode,and PEP is continued based on PUP-PEP to finally reduce the workpiece surface roughness value to R_(a)0.27μm.The proposed PUP-PEP technology marks the implementation of‘polishing’instead of conventional rough-finish machining processes,presenting a new approach to the surface post-processing of metal near-net fabrication technologies.
基金supported by the 2002 Ministry of Education Project for Science and Technology (2002,No.77)
文摘The effects of linear falling ramp reset pulse related to addressing operation in an alternating current plasma display panel （AC PDP） were studied. The wall charge waveforms were measured by the electrode balance method in a 12-inch coplanar AC PDP. The wall charge waveforms show the relationship between the slope ratio of the falling ramp reset pulse and the wall charges at the end of the falling ramp reset pulse which influences the addressing stability. Then the effects of the slope ratio of the linear falling ramp reset pulse on the addressing voltage and addressing time were investigated. The experimental results show that the minimum addressing voltage increases with the increase of the slope ratio of the falling ramp reset pulse, and so does the minimum addressing time. Based on the experimental results, the optimization of the addressing time and the slope ratio of the falling ramp pulse is discussed.
基金This work was supported by the National Natural Science Foundation of China-State Grid Corporation Joint Fund for Smart Grid(No.U1766219)。
文摘The high-voltage high-power press-packed IGBT(PPI)devices are the key component of the DC transmission apparatus.A PPI device is composed of several PPI submodules.In general,the PPI submodule works in a state of repetitive turn-on and turn-off,and the corresponding working voltage is the positive periodic square waveform(PPSW)voltage,which is much different from the conventional AC or DC voltage.In addition,insulation capability is one of the most critical challenges in the design and fabrication of PPI devices.To improve the insulation capability of the device,composite insulation structures with multiple dielectrics are usually employed.Under the PPSW voltage,it is essential to analyze the transient electric field to solve the insulation challenge of the PPI devices.However,the electric field of the PPI is often calculated under the electrostatic field or DC field.Moreover,the transient characteristics of the electric field are ignored.Therefore,this paper focuses on the analysis of the transient characteristics of the electric field of the PPI submodule under the PPSW voltage.The influences of the waveform parameters of the PPSW voltage on the transient characteristics are demonstrated in detail.This study is significant for the insulation analysis and design of the PPIs.
基金supported by the National Natural Science Foundation of China (Grant Nos 60706030, 20827007)the National Basic Research Program of China ("973" Project)(Grant No 2007CB310504)
文摘A micro sensor chip of High-field Asymmetric Waveform Ion Mobility Spectrometry(FAIMS) was designed and fabricated by inductively coupled plasma(ICP) etching on the both sides of silicon and double silicon-glass bonding,with dimensions of 18.8 mm×12.4 mm×1.2mm.The sample ions were created at ambient pressure by VUV lamp ion source,which was equipped with a 10.6 eV photo discharge lamp(λ=116.5 nm).The 2-pentanone was adopted to illustrate the influences of high-field rectangular asymmetric waveform voltage amplitude,frequency and carrier gas flow rate on the performance of FAIMS sensor chip.The experiment results showed that with the frequency or carrier gas flow rate increasing,or voltage amplitude decreasing,the FAIMS sensitivity increases,and that the resolution decreases with the increasing of the frequency or flow rate.The FAIMS simulation results based on the SIMION software was in agreement with the experimental results.The FAIMS detection sensitivity experiment showed that the FAIMS sensor chip can detect positive and negative ions simultaneously,and has detection sensitivity as low as 0.1 ppm for acetic acid.
基金Supported by National Natural Science Foundation of China(11175193)
文摘Dual harmonic systems have been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in a dual rf system, the potential well, the sub-buckets in the bunch and the multi-solutions of the phase equation are studied theoretically in this paper. Based on these theoretical studies, optimization of bunching factor and rf voltage waveform are made for the dual harmonic rf system in the upgrade phase of the China Spallation Neutron Source Rapid Cycling Synchrotron （CSNS/RCS）. In the optimization process, the simulation with space charge effect is done using a newly developed code. C-SCSIM.
