As a general feature, the electric field of a localized electric charge distribution diminishes as the distance from the distribution increases;there are exceptions to this feature. For instance, the electric field of...As a general feature, the electric field of a localized electric charge distribution diminishes as the distance from the distribution increases;there are exceptions to this feature. For instance, the electric field of a charged ring (being a localized charge distribution) along its symmetry axis perpendicular to the ring through its center rather than as expected being a diminishing field encounters a local maximum bump. It is the objective of this research-oriented study to analyze the impact of this bump on the characteristics of a massive point-like charged particle oscillating along the symmetry axis. Two scenarios with and without gravity along the symmetry axis are considered. In addition to standard kinematic diagrams, various phase diagrams conducive to a better understanding are constructed. Applying Computer Algebra System (CAS), [1] [2] most calculations are carried out symbolically. Finally, by assigning a set of reasonable numeric parameters to the symbolic quantities various 3D animations are crafted. All the CAS codes are included.展开更多
A pulse generator with a voltage rise time of～1.5 ns and voltage amplitude variable from 30 kV to 200 kV was designed for generating runaway electron beams in atmospheric pressure air with different interelectrode ga...A pulse generator with a voltage rise time of～1.5 ns and voltage amplitude variable from 30 kV to 200 kV was designed for generating runaway electron beams in atmospheric pressure air with different interelectrode gaps.The influence of the voltage amplitude and gap length on the generation was studied.In the gas diode geometry under study,the gap voltage at which the generation of a runaway electron beam begins was determined.Decreasing the voltage pulse amplitude does not increase the beam current pulse width measured with a time resolution of～0.1 ns.It is shown that the escape of beam electrons to the downstream of the foil is sync in time with the voltage drop across the gap,and that the delay of beam current generation increases gradually from 1.1 ns to 2.6 ns as the voltage pulse amplitude across the gap decreases from～100 kV to 40 kV.展开更多
This paper presents a circuit model for thin avalanche photodiodes （APDs）. In this model, the nonuniformity of the electric filed in the multiplication region is modeled using a stepwise method. The model also tries...This paper presents a circuit model for thin avalanche photodiodes （APDs）. In this model, the nonuniformity of the electric filed in the multiplication region is modeled using a stepwise method. The model also tries to take the effects of carrier＇s position dependent properties, like carder＇s dead length and the history of carder＇s previous ionization into account by developing an effective electric field in the multiplication region. The output photocurrent and multiplication gain obtained from the proposed model for different lengths of the multi- plication region achieve a good agreement in comparison with available experimental data. In addition, calculated excess noise factor reveals the model ability for noise and sensitivity analysis.展开更多
Diffuse and spark discharges are formed and studied during breakdowns with nonuniform electric field in nitrogen,air,and argon at elevated pressures and pulse repetition frequency of 400 Hz.Negative-polarity voltage p...Diffuse and spark discharges are formed and studied during breakdowns with nonuniform electric field in nitrogen,air,and argon at elevated pressures and pulse repetition frequency of 400 Hz.Negative-polarity voltage pulses of the amplitude 20 kV,width at the base of 15 ns and rise time of 2 ns are applied to the electrode with a small radius of curvature.In the conditions of generation of runaway electron beams and X-rays,a CCD camera records the time of the diffuse discharge formation and its duration prior to its transition to a spark one.In all three gases,the diffuse discharge is formed during the time not exceeding 1 ns,when the bright spots appear on cathode in argon and air resulting in the beginning of the spark channel propagation.展开更多
文摘As a general feature, the electric field of a localized electric charge distribution diminishes as the distance from the distribution increases;there are exceptions to this feature. For instance, the electric field of a charged ring (being a localized charge distribution) along its symmetry axis perpendicular to the ring through its center rather than as expected being a diminishing field encounters a local maximum bump. It is the objective of this research-oriented study to analyze the impact of this bump on the characteristics of a massive point-like charged particle oscillating along the symmetry axis. Two scenarios with and without gravity along the symmetry axis are considered. In addition to standard kinematic diagrams, various phase diagrams conducive to a better understanding are constructed. Applying Computer Algebra System (CAS), [1] [2] most calculations are carried out symbolically. Finally, by assigning a set of reasonable numeric parameters to the symbolic quantities various 3D animations are crafted. All the CAS codes are included.
基金Project supported by Russian Foundation for Basic Research （12-08-91150-GFEN_a）, National Natural Science Foundation of China （51222701, 51207154, 51211120183）, National Basic Research Program of China （973 Program） （20llCB209402）, Opening Project of State Key Laboratory of Electrical Insulation and Power Equipment in Xi＇an Jiaotong University （EIPEI2204）, Chinese Academy of Sciences Visiting Professorship for Senior International Scientists （2012TtG0021）.
文摘A pulse generator with a voltage rise time of～1.5 ns and voltage amplitude variable from 30 kV to 200 kV was designed for generating runaway electron beams in atmospheric pressure air with different interelectrode gaps.The influence of the voltage amplitude and gap length on the generation was studied.In the gas diode geometry under study,the gap voltage at which the generation of a runaway electron beam begins was determined.Decreasing the voltage pulse amplitude does not increase the beam current pulse width measured with a time resolution of～0.1 ns.It is shown that the escape of beam electrons to the downstream of the foil is sync in time with the voltage drop across the gap,and that the delay of beam current generation increases gradually from 1.1 ns to 2.6 ns as the voltage pulse amplitude across the gap decreases from～100 kV to 40 kV.
文摘This paper presents a circuit model for thin avalanche photodiodes （APDs）. In this model, the nonuniformity of the electric filed in the multiplication region is modeled using a stepwise method. The model also tries to take the effects of carrier＇s position dependent properties, like carder＇s dead length and the history of carder＇s previous ionization into account by developing an effective electric field in the multiplication region. The output photocurrent and multiplication gain obtained from the proposed model for different lengths of the multi- plication region achieve a good agreement in comparison with available experimental data. In addition, calculated excess noise factor reveals the model ability for noise and sensitivity analysis.
基金Project supported by Russian Foundation for Basic Research(under Grant12-08-00105_a)
文摘Diffuse and spark discharges are formed and studied during breakdowns with nonuniform electric field in nitrogen,air,and argon at elevated pressures and pulse repetition frequency of 400 Hz.Negative-polarity voltage pulses of the amplitude 20 kV,width at the base of 15 ns and rise time of 2 ns are applied to the electrode with a small radius of curvature.In the conditions of generation of runaway electron beams and X-rays,a CCD camera records the time of the diffuse discharge formation and its duration prior to its transition to a spark one.In all three gases,the diffuse discharge is formed during the time not exceeding 1 ns,when the bright spots appear on cathode in argon and air resulting in the beginning of the spark channel propagation.
