An electromagnetic field is generated through the accelerating movement of two equal but opposite charges of a single dipole. An electromagnetic field can also be generated by a time-varying infinitesimal point charge...An electromagnetic field is generated through the accelerating movement of two equal but opposite charges of a single dipole. An electromagnetic field can also be generated by a time-varying infinitesimal point charge. In this study, a comparison between the electromagnetic fields of an infinitesimal point charge and a dipole has been presented. First, the time-domain potential function of a point source in a 3D conductive medium is derived. Then the electric and magnetic fields in a 3D homogeneous lossless space are derived via the relation between the potential and field. The field differences between the infinitesimal point charge and the dipole in the step-off time, far-source, and near-source zones are analyzed, and the accuracy of the solutions from these sources is investigated. It is also shown that the field of the infinitesimal point charge in the near-source zone is different from that of the dipole, whereas the far-source zone fields of these two sources are identical. The comparison of real and simulated data shows that the infinitesimal point charge represents the real source better than the divole source.展开更多
Formation of a quasi-stationary discharge or quasi-stationary emission mode in the explosive-emission electron sources is related to the current limitation resulting from the emissive ability saturation of cathode pla...Formation of a quasi-stationary discharge or quasi-stationary emission mode in the explosive-emission electron sources is related to the current limitation resulting from the emissive ability saturation of cathode plasma with its expansion. The paper shows that in the process of the discharge current stabilization in the explosive-emission sources with the point- or blade-type emitters the essential role belongs to the electron beam space charge. Availability of the space charge results in limitation of the current growth velocity at the initial discharge phase and, hence, restricts the emissive ability of the cathode plasma and contributes to its saturation. In the vacuum diodes with multiemitter cathodes, the space charge availability increases the cathode operation stability and can provide obtaining of quasi-stationary beam current values or close to them resulting in formation of a plasma emission surface at the cathode close to the continuous one.展开更多
A new 14.5 GHz Electron Cyclotron Resonance (ECR) ion source has been constructed over the last two years. The source was designed and tested by making use of the latest results from ECR ion source development, such a...A new 14.5 GHz Electron Cyclotron Resonance (ECR) ion source has been constructed over the last two years. The source was designed and tested by making use of the latest results from ECR ion source development, such as high mirror magnetic field, large plasma volume, and biased probe. 140uA of O^7+, 185uA of Ar^11+ and 50uA of Xe^26+ could be produced with a RF power of 800 W. The intense beams of highly charged metallic ions are produced by means of the method of a metal evaporation oven and volatile compound through axial access. The test results are 130uA of Ca^11+, 70uA of Ca^12+ and 65uA of Fe^lo+. The ion source has been put into operation for the cyclotron at the institute of Modern Physics (IMP).展开更多
A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of th...A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of the rectifier module of the DC charging pile under weak grid as well as the dead zone and nonlinearity of switching devices during charging.Firstly,the parallel repetitive control was constructed in the inner current loop,and the proportional-integral(PI)+repetitive controller based on parallel structure was designed.For system compensation,a second-order low-pass filter was selected to correct the system,and the network-side current harmonics were actively suppressed without increasing the filtering device,which effectively improves the quality of grid-connected current.Secondly,based on the synthetic vector method,the controller parameters were designed to realize the elimination of main pole by establishing two synchronous rotation coordinate system vector differential equations,so as to realize the inductanceless decoupling to cope with the influence of network-side inductance fluctuation on the stability of the control system under weak grid.By theoretical analysis and simulation,the proposed control strategy was embedded into the self-developed digital signal processor for the rectifier module of DC charging pile,simulated dynamic and steady-state operation experiments were conducted,and comparative analysis was performed to prove the feasibility of the proposed control strategy.展开更多
The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the ...The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the oil accumulation. According to oil geochemical analysis and oil-source correlation, the oil in deep and shallow reservoirs of the Lukeqin Oilfield presents different physical and saturated hydrocarbon mass spectrum characteristics. The Triassic heavy oil is from the northern Upper Permian lacustrine source rocks, and the light oil represented by the Yudong-9 Well is from the northwestern Lower Jurassic coal-measure source rocks. The timing of oil charging was determined by K/Ar isotope dating, reservoir fluid inclusion analysis and the evolution history of different source rocks. In summary, the accumulation process consists of two stages. From the end of Triassic to early Jurassic, the northern Permian source kitchen generated a considerable amount of oil, which was finally degraded to heavy oil, migrated to the south and then accumulated. The northwestern Jurassic coal-measure source kitchen began to generate oil at the end of Cretaceous, while the northern source kitchen could only generate a little hydrocarbon. The heavy oil and the light oil have different source rock locations, migration directions and accumulation times. The migration of hydrocarbon source kitchens affects the distribution of heavy oil and light oil reservoirs at the present time.展开更多
This paper presents a conceptual design for the first tentative surface muon source based on the proton beam provided by China Spallation Neutron Source （CSNS）. We have calcu- lated the optimal parameters of solid m...This paper presents a conceptual design for the first tentative surface muon source based on the proton beam provided by China Spallation Neutron Source （CSNS）. We have calcu- lated the optimal parameters of solid muon target, in which the method of Monte Carlo simula- tion is used to obtain the optimal muon beam parameters, such as beam fiuence rate, momentum spread and phase space distribution. A simple muon transport beamline system was also designed, which could transport the muons emitted from the muon target into the experimental area, where positrons from muon decay in a test sample are detected by a spectrometer. The beam optics of this new beam line is also described.展开更多
Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： appr...Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： approximate 25 times, the accuracy of DC output voltage： ±5%, manual control and automatic control.展开更多
Charge breeding technique is used for RIB （radioactive ion beam） production in order of optimizing the re-acceleration of the radioactive isotopes produced by a primary beam in a thick target. Charge breeding is ach...Charge breeding technique is used for RIB （radioactive ion beam） production in order of optimizing the re-acceleration of the radioactive isotopes produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1＋ to a desired value n＋. In some experiments, a continuous RIB of a given energy may be required. To reach this goal, a charge breeding device based on a hollow gun EBIS （electron beam ion source） has been proposed by the author recently. That EBIS, in principle, can be capable to realize a CW （continuous wave） operation. A sufficiently high focusing magnetic field could reduce to zero the hole radius in the EBIS electron beam. However, a smaller efficiency in the ion charge state increase should be expected. A code developed for studying the ion selective containment in a EBIS has been modified and used to simulate the ion charge state breeding. The effects of the hollow electron beam on the breeding rate have been studied.展开更多
针对可再生能源、电解槽和储能设备集成的孤岛直流微电网制氢系统,提出了1种考虑储能荷电状态(state of charge,SoC)的优化控制策略.首先,对碱性电解槽的制氢效率特性进行分析,提出了1种制氢效率随母线电压变化而自适应调整的优化控制方...针对可再生能源、电解槽和储能设备集成的孤岛直流微电网制氢系统,提出了1种考虑储能荷电状态(state of charge,SoC)的优化控制策略.首先,对碱性电解槽的制氢效率特性进行分析,提出了1种制氢效率随母线电压变化而自适应调整的优化控制方法,通过与储能系统协调互补,将制氢效率保持在较高的范围内.当储能SoC越过上下限时,设计了1种不依赖通信的SoC主动恢复控制策略,确保储能系统的安全运行.其次,设计了1种考虑极端工况下的功率协调控制策略,通过各个运行模式之间的灵活切换来保证直流微电网的稳定运行.最后,通过MATLAB/Simulink仿真平台对所提控制策略的有效性进行了验证.展开更多
自同步电压源逆变器SSVSI(self-synchronized voltage source inverter)因能改善新型电力系统电压与频率稳定性而备受关注。为解决多光储SSVSI并联运行时储能荷电状态SOC(state-of-charge)不均衡、直流侧电压波动与交流侧输出功率振荡...自同步电压源逆变器SSVSI(self-synchronized voltage source inverter)因能改善新型电力系统电压与频率稳定性而备受关注。为解决多光储SSVSI并联运行时储能荷电状态SOC(state-of-charge)不均衡、直流侧电压波动与交流侧输出功率振荡的问题,首先分析了多光储SSVSI并联系统交直流侧功率响应的动态特性,然后提出了多光储SSVSI并联系统协调控制方法。该协调控制方法通过考虑储能SOC的协调分配策略与储能功率前馈控制,实现储能SOC动态均衡,改善直流侧电压的动态特性。此外,通过阻尼增强控制抑制了交流侧输出功率振荡。最后,通过仿真和RT-LAB实验验证了所提控制方法的有效性。展开更多
基金supported by Chinese National Programs for Fundamental Research and Development(No.2012CB416605)the National Natural Science Foundation of China(No.41174090)Development Project of National Key Scientific Equipment(No.ZDYZ2012-1-05-04)
文摘An electromagnetic field is generated through the accelerating movement of two equal but opposite charges of a single dipole. An electromagnetic field can also be generated by a time-varying infinitesimal point charge. In this study, a comparison between the electromagnetic fields of an infinitesimal point charge and a dipole has been presented. First, the time-domain potential function of a point source in a 3D conductive medium is derived. Then the electric and magnetic fields in a 3D homogeneous lossless space are derived via the relation between the potential and field. The field differences between the infinitesimal point charge and the dipole in the step-off time, far-source, and near-source zones are analyzed, and the accuracy of the solutions from these sources is investigated. It is also shown that the field of the infinitesimal point charge in the near-source zone is different from that of the dipole, whereas the far-source zone fields of these two sources are identical. The comparison of real and simulated data shows that the infinitesimal point charge represents the real source better than the divole source.
文摘Formation of a quasi-stationary discharge or quasi-stationary emission mode in the explosive-emission electron sources is related to the current limitation resulting from the emissive ability saturation of cathode plasma with its expansion. The paper shows that in the process of the discharge current stabilization in the explosive-emission sources with the point- or blade-type emitters the essential role belongs to the electron beam space charge. Availability of the space charge results in limitation of the current growth velocity at the initial discharge phase and, hence, restricts the emissive ability of the cathode plasma and contributes to its saturation. In the vacuum diodes with multiemitter cathodes, the space charge availability increases the cathode operation stability and can provide obtaining of quasi-stationary beam current values or close to them resulting in formation of a plasma emission surface at the cathode close to the continuous one.
基金Equipment Upgrading Fund and '9.5' Fund for Fundamental Research from the Chinese Academy of Sciences
文摘A new 14.5 GHz Electron Cyclotron Resonance (ECR) ion source has been constructed over the last two years. The source was designed and tested by making use of the latest results from ECR ion source development, such as high mirror magnetic field, large plasma volume, and biased probe. 140uA of O^7+, 185uA of Ar^11+ and 50uA of Xe^26+ could be produced with a RF power of 800 W. The intense beams of highly charged metallic ions are produced by means of the method of a metal evaporation oven and volatile compound through axial access. The test results are 130uA of Ca^11+, 70uA of Ca^12+ and 65uA of Fe^lo+. The ion source has been put into operation for the cyclotron at the institute of Modern Physics (IMP).
基金supported by National Natural Science Foundation of China(No.61903291)Shaanxi Province Key R&D Program(No.2022GY-134)。
文摘A control strategy of repetitive control without inductorance decoupling was proposed to address the problem of high total harmonic distortion(THD)rate of the network-side current caused by the reduced stability of the rectifier module of the DC charging pile under weak grid as well as the dead zone and nonlinearity of switching devices during charging.Firstly,the parallel repetitive control was constructed in the inner current loop,and the proportional-integral(PI)+repetitive controller based on parallel structure was designed.For system compensation,a second-order low-pass filter was selected to correct the system,and the network-side current harmonics were actively suppressed without increasing the filtering device,which effectively improves the quality of grid-connected current.Secondly,based on the synthetic vector method,the controller parameters were designed to realize the elimination of main pole by establishing two synchronous rotation coordinate system vector differential equations,so as to realize the inductanceless decoupling to cope with the influence of network-side inductance fluctuation on the stability of the control system under weak grid.By theoretical analysis and simulation,the proposed control strategy was embedded into the self-developed digital signal processor for the rectifier module of DC charging pile,simulated dynamic and steady-state operation experiments were conducted,and comparative analysis was performed to prove the feasibility of the proposed control strategy.
基金supported by the Basic Research Development Program of China "Accumulation mechanisms and distribution patterns of hydrocarbon intypical superimposed basins of west China" (973 Program,No.2006CB202303)
文摘The Lukeqin structural belt is the main heavy oil accumulation zone in the Turpan-Hami Basin. The recent discovery of light oil in the Triassic indicates that there may be multiple source kitchens contributing to the oil accumulation. According to oil geochemical analysis and oil-source correlation, the oil in deep and shallow reservoirs of the Lukeqin Oilfield presents different physical and saturated hydrocarbon mass spectrum characteristics. The Triassic heavy oil is from the northern Upper Permian lacustrine source rocks, and the light oil represented by the Yudong-9 Well is from the northwestern Lower Jurassic coal-measure source rocks. The timing of oil charging was determined by K/Ar isotope dating, reservoir fluid inclusion analysis and the evolution history of different source rocks. In summary, the accumulation process consists of two stages. From the end of Triassic to early Jurassic, the northern Permian source kitchen generated a considerable amount of oil, which was finally degraded to heavy oil, migrated to the south and then accumulated. The northwestern Jurassic coal-measure source kitchen began to generate oil at the end of Cretaceous, while the northern source kitchen could only generate a little hydrocarbon. The heavy oil and the light oil have different source rock locations, migration directions and accumulation times. The migration of hydrocarbon source kitchens affects the distribution of heavy oil and light oil reservoirs at the present time.
基金supported by National Natural Science Foundation of China (No. 11075154)
文摘This paper presents a conceptual design for the first tentative surface muon source based on the proton beam provided by China Spallation Neutron Source （CSNS）. We have calcu- lated the optimal parameters of solid muon target, in which the method of Monte Carlo simula- tion is used to obtain the optimal muon beam parameters, such as beam fiuence rate, momentum spread and phase space distribution. A simple muon transport beamline system was also designed, which could transport the muons emitted from the muon target into the experimental area, where positrons from muon decay in a test sample are detected by a spectrometer. The beam optics of this new beam line is also described.
文摘Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： approximate 25 times, the accuracy of DC output voltage： ±5%, manual control and automatic control.
文摘Charge breeding technique is used for RIB （radioactive ion beam） production in order of optimizing the re-acceleration of the radioactive isotopes produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1＋ to a desired value n＋. In some experiments, a continuous RIB of a given energy may be required. To reach this goal, a charge breeding device based on a hollow gun EBIS （electron beam ion source） has been proposed by the author recently. That EBIS, in principle, can be capable to realize a CW （continuous wave） operation. A sufficiently high focusing magnetic field could reduce to zero the hole radius in the EBIS electron beam. However, a smaller efficiency in the ion charge state increase should be expected. A code developed for studying the ion selective containment in a EBIS has been modified and used to simulate the ion charge state breeding. The effects of the hollow electron beam on the breeding rate have been studied.
文摘针对可再生能源、电解槽和储能设备集成的孤岛直流微电网制氢系统,提出了1种考虑储能荷电状态(state of charge,SoC)的优化控制策略.首先,对碱性电解槽的制氢效率特性进行分析,提出了1种制氢效率随母线电压变化而自适应调整的优化控制方法,通过与储能系统协调互补,将制氢效率保持在较高的范围内.当储能SoC越过上下限时,设计了1种不依赖通信的SoC主动恢复控制策略,确保储能系统的安全运行.其次,设计了1种考虑极端工况下的功率协调控制策略,通过各个运行模式之间的灵活切换来保证直流微电网的稳定运行.最后,通过MATLAB/Simulink仿真平台对所提控制策略的有效性进行了验证.
文摘自同步电压源逆变器SSVSI(self-synchronized voltage source inverter)因能改善新型电力系统电压与频率稳定性而备受关注。为解决多光储SSVSI并联运行时储能荷电状态SOC(state-of-charge)不均衡、直流侧电压波动与交流侧输出功率振荡的问题,首先分析了多光储SSVSI并联系统交直流侧功率响应的动态特性,然后提出了多光储SSVSI并联系统协调控制方法。该协调控制方法通过考虑储能SOC的协调分配策略与储能功率前馈控制,实现储能SOC动态均衡,改善直流侧电压的动态特性。此外,通过阻尼增强控制抑制了交流侧输出功率振荡。最后,通过仿真和RT-LAB实验验证了所提控制方法的有效性。
