In this paper a commercial CFD （computational fluid dynamics） code FLUENT has been used and modified for the axisymmetric swirl and time-dependent simulation of an atmospheric pressure argon arc in an external axial...In this paper a commercial CFD （computational fluid dynamics） code FLUENT has been used and modified for the axisymmetric swirl and time-dependent simulation of an atmospheric pressure argon arc in an external axial magnetic field （AMF）. The computational domain includes the arc itself and the anodic region. Numerical results demonstrate that the AMF substantially increases the tangential component of the plasma velocity. The resulting centrifugal force for the plasma rotation impels it to travel to the arc mantel and as a result, a low-pressure region appears at the arc core. With the AMF, the arc presents a hollow bell shape and correspondingly, the maximal values of the temperature, pressure and current density on the anode surface are departing from the arc centreline.展开更多
Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conser...Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conservation equations, generalized ohm's law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.展开更多
To improve the limiting current interruption capability and minimizing vacuum interrupter with axial magnetic field （AMF） electrodes, it is significant to investigate the vacuum arc behaviours between the contacts. ...To improve the limiting current interruption capability and minimizing vacuum interrupter with axial magnetic field （AMF） electrodes, it is significant to investigate the vacuum arc behaviours between the contacts. AMF distributions of the slot type electrodes were studied by both numerical analysis and experiments. Furthermore, the behaviours of vacuum arcs for different parameters of the slot type AMF electrodes were investigated by using high-speed CCD camera. The influences of gap distance, contact diameter and phase shift time between AMF and arc current on the vacuum arc were investigated. The results provide a reference for research and development of vacuum interrupters with slot type or other types of AMF electrode.展开更多
After current zero,which is the moment when the vacuum circuit breaker interrupts a vacuum arc,sheath development is the first process in the dielectric recovery process.An axial magnetic field（AMF） is widely used i...After current zero,which is the moment when the vacuum circuit breaker interrupts a vacuum arc,sheath development is the first process in the dielectric recovery process.An axial magnetic field（AMF） is widely used in the vacuum circuit breaker when the high-current vacuum arc is interrupted.Therefore,it is very important to study the influence of different AMF amplitudes on the sheath development.The objective of this paper is to study the influence of different AMF amplitudes on the sheath development from a micro perspective.Thus,the particle in cell-Monte Carlo collisions（PIC-MCC） method was adopted to develop the sheath development model.We compared the simulation results with the experimental results and then validated the simulation.We also obtained the speed of the sheath development and the energy density of the ions under different AMF amplitudes.The results showed mat the larger the AMF amplitudes are,the faster the sheath develops and the lower the ion energy density is,meaning the breakdown is correspondingly more difficult.展开更多
Characteristics of the arc voltage under different profiles of axial magnetic field were investigated experimentally in a detachable vacuum chamber with five pairs of specially designed electrodes generating both bell...Characteristics of the arc voltage under different profiles of axial magnetic field were investigated experimentally in a detachable vacuum chamber with five pairs of specially designed electrodes generating both bell-shaped and saddle-shaped magnetic field profile. The arc column and cathode spot images were photographed by a high speed digital camera. The dependence of the arc voltage on arcing evolution is analyzed. It is indicated that the axial magnetic field profile could affect the arc behaviors significantly, and the arc voltage is closely related to the arc light intensity.展开更多
A helix type slow wave structure filled with plasma is immersed in a strong longitudinal magnetic field. Taking into account the effect of the plasma and the dielectric, the system is separated radially into three reg...A helix type slow wave structure filled with plasma is immersed in a strong longitudinal magnetic field. Taking into account the effect of the plasma and the dielectric, the system is separated radially into three regions. By means of the sheath model and Maxwell equation, the distribution of the electromagnetic field is established. Using the boundary conditions of each region, the dispersion relation of the slow wave structure is derived. The trend of change for the radial profile of the axial electric field is analysed respectively in different plasma densities, plasma column radius and dielectric constant by numerical computation. Some useful results are obtained on the basis of the discussion.展开更多
We consider the radiation from the beam electrons traveling in a strong uniform axial magnetic field and an axial alternating electric field of wavelength Aw generated by a voltage-supplied pill-box cavity. The beam e...We consider the radiation from the beam electrons traveling in a strong uniform axial magnetic field and an axial alternating electric field of wavelength Aw generated by a voltage-supplied pill-box cavity. The beam electrons emit genuine laser radiation that propagates only in the axial direction through free-electron two- quantum Stark radiation. We find that laser radiation takes place only at the expense of the axial kinetic energy when Aw 〈〈 c/（ωc/γ）, where ωc/γ is the relativistic electron--cyclotron frequency. We formulate the laser power based on quantum-wiggler electrodynamics, and envision a laser of length lore with estimated power 0.1 GW/（kA） in the 10-4 cm wavelength range.展开更多
The modulation of absorption manner in helicon discharge by changing the profile of low axial magnetic field is explored experimentally in this work. The experiments are carried out in Boswell-type antenna driven by 1...The modulation of absorption manner in helicon discharge by changing the profile of low axial magnetic field is explored experimentally in this work. The experiments are carried out in Boswell-type antenna driven by 13.56-MHz power source in 0.35-Pa argon environment. The peak of the external non-uniform magnetic field （Bex） along the axis is observed in a range from 0 Gs to 250 Gs （1 Gs=10^-4 T）, where the electron density varies from 0.5×10^16 m^-3 to 9×10^16 m^-3. When Bex is located near the tube upper end sealed by a dielectric plate, or near the tube bottom end connected with a diffusion chamber, the plasmas are centralized in the tube in the former case while the strong luminance appears between the edge of the tube and the axial line in the latter case. When Bex is located in the middle of the antenna, moreover, an effective resistance （Reff） peak appears apparently with increasing magnetic field. The glow moves toward first the edge of the tube and then the two antenna legs as the magnetic field increases. The discharge in this case is caused by the absorption of Trivelpiece-Gould （TG） wave. It is suggested that Bex is located in the middle of the antenna to obtain a higher efficiency of power transfer.展开更多
The effect of an axial magnetic field （AMF） on an old xenon short-arc lamp is experimentally investigated in this work. As the AMF increases up to 18 roT, the visible radiation power and electric power ascend more t...The effect of an axial magnetic field （AMF） on an old xenon short-arc lamp is experimentally investigated in this work. As the AMF increases up to 18 roT, the visible radiation power and electric power ascend more than 80% and 70% respectively, and the radiation efficiency is improved by 23% for the best increment at 12 mT AMF. The measurement of radiation intensity shows that the increment of radiation intensity comes mostly from the plasma area close to the cathode tip, and partially from the other area of the arc column. Successive images of the arc indicate that the arc column not only rotates about its axis, but revolves around the axis of electrodes with the AMF. The arc column structure is constricted, distorted and elongated as the AMF increases. It is suggested that the improvements of the radiation intensity and radiation efficiency are attributed to the constriction of the arc column, which is mainly induced by the enhanced cathode jet.展开更多
Effect of the axial magnetic field （AMF） on resisting the constriction of a highcurrent vacuum arc is studied in this paper. Two typical AMF distributions were investigated, i.e., the traditional bell-shaped AMF, an...Effect of the axial magnetic field （AMF） on resisting the constriction of a highcurrent vacuum arc is studied in this paper. Two typical AMF distributions were investigated, i.e., the traditional bell-shaped AMF, and the saddle-shaped AMF. Experiments were conducted in a detachable vacuum chamber with arms arc current in the range of 10 kA to 25 kA. The arc column was photographed by a high-speed digital camera with an exposure time of 2 microseconds. The constriction of the vacuum arc was compared by processing the images of the arc column under the two different field configurations and numerically determining the dimensions of the arc column near the electrodes. It was also confirmed that the AMF distribution had a significant influence on its effectiveness in resisting arc constriction. of the arc is more influential than that at the Furthermore, the AMF strength near the periphery centre of the electrodes in resisting arc constriction.展开更多
Recent results on the distribution of vacuum arc cathode spots （CSs） in nonuniform axial magnetic field （AMF） are presented. Based on previous studies, we deem that two contrary influences of AMF, inward effect an...Recent results on the distribution of vacuum arc cathode spots （CSs） in nonuniform axial magnetic field （AMF） are presented. Based on previous studies, we deem that two contrary influences of AMF, inward effect and outward effect, are attributed to CSs distribution. With this notion, we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes. Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device （CCD） camera. Experimental results agreed well with the theoretical analysis.展开更多
As the main source of the vacuum arc plasma,cathode spots(CSs)play an important role on the behaviors of the vacuum arc.Their characteristics are affected by many factors,especially by the magnetic field.In this paper...As the main source of the vacuum arc plasma,cathode spots(CSs)play an important role on the behaviors of the vacuum arc.Their characteristics are affected by many factors,especially by the magnetic field.In this paper,the characteristics of the plasma jet from a single CS in vacuum arc under external axial magnetic field(AMF)are studied.A multi-species magneto-hydro-dynamic(MHD)model is established to describe the vacuum arc.The anode temperature is calculated by the anode activity model based on the energy flux obtained from the MHD model.The simulation results indicate that the external AMF has a significant effect on the characteristic of the plasma jet.When the external AMF is high enough,a bright spot appears on the anode surface.This is because with a higher AMF,the contraction of the diffused arc becomes more obvious,leading to a higher energy flux to the anode and thus a higher anode temperature.Then more secondary plasma can be generated near the anode,and the brightness of the‘anode spot’increases.During this process,the arc appearance gradually changes from a cone to a dumbbell shape.In this condition,the arc is in the diffuse mode.The appearance of the plasma jet calculated in the model is consistent with the experimental results.展开更多
Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab alon...Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab along a growing radiation. The set of coupled nonlinear differential equations of motion is solved to study the electron dynamics. For three sets of parameters, in high power CFEL, it is found that an axial magnetic field is always necessary to keep the electron beam in the interaction region and its optimal strength is reported for each case. At the injection point, the electron beam’s distance above the dielectric surface is kept at a minimum value so that the electrons neither hit the dielectric nor move away from it to the weaker radiation fields and out of the interaction region. The optimal electron beam radius and current are thereby calculated. This analysis is in agreement with two previous numerical studies for a cylindrical waveguide but is at odds with analytical treatments of a flat dielectric that does not use an axial magnetic field. This is backed by an interesting physical reasoning.展开更多
The solutions to the electromagnetic field excited by a long axial current outside a conductive and magnetic cylindrical shell of finite length are studied in this paper. The more accurate analytical solutions are obt...The solutions to the electromagnetic field excited by a long axial current outside a conductive and magnetic cylindrical shell of finite length are studied in this paper. The more accurate analytical solutions are obtained by solving the proper boundary value problems by the separation variable method. Then the solutions are simplified according to asymptotic formulas of Bessel functions. Compared with the accurate solutions, the simplified solutions do not contain the Bessel functions and the inverse operation of the singular matrix, and can be calculated out fast by computers. The simplified solutions are more suitable for the cylindrical shell of high permeability and conductivity excited by a high frequency source. Both of the numerical results and the physical experimental results validate the simplified solutions obtained.展开更多
As one of the relativistic electron tubes having compact configuration and high efficient output, the relativistic magnetron with direct axial radiation is very attractive in pulsed power and high power microwave fiel...As one of the relativistic electron tubes having compact configuration and high efficient output, the relativistic magnetron with direct axial radiation is very attractive in pulsed power and high power microwave fields for industrial and military applications. In this paper, the experimental investigation of a relativistic magnetron with axial TE11 mode radiation is reported. Under a total length of - 0.3 m, volume of - 0.014 m3, working at an applied voltage of 508 kV and a magnetic field of - 0.31 T, the relativistic magnetron radiates a microwave of 540 MW with the TE11 mode at 2.35 GHz in the axial direction. The power conversion efficiency is 15.0%. After a lot of shots, the detected amplitudes of microwaves are nearly the same. The fluctuations of wave amplitudes are less than 0.3 dB.展开更多
In order to master the magnetic field distribution of submarines in the air completely and exactly and study the magnetic stealthy performance of submarine,a mathematic model of submarine magnetic field extrapolation ...In order to master the magnetic field distribution of submarines in the air completely and exactly and study the magnetic stealthy performance of submarine,a mathematic model of submarine magnetic field extrapolation is built based on the boundary element method(BEM).An experiment is designed to measure three components of magnetic field on the envelope surface surrounding a model submarine.The data in different heights above the model submarine are obtained by use of tri-axial magnetometers.The results show that this extrapolation model has good stabilities and high accuracies compared the measured data with the extrapolated data.Moreover,the model can reflect the submarine magnetic field distribution in the air exactly,and is valuable in practical engineering.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10375065 and 10675122)
文摘In this paper a commercial CFD （computational fluid dynamics） code FLUENT has been used and modified for the axisymmetric swirl and time-dependent simulation of an atmospheric pressure argon arc in an external axial magnetic field （AMF）. The computational domain includes the arc itself and the anodic region. Numerical results demonstrate that the AMF substantially increases the tangential component of the plasma velocity. The resulting centrifugal force for the plasma rotation impels it to travel to the arc mantel and as a result, a low-pressure region appears at the arc core. With the AMF, the arc presents a hollow bell shape and correspondingly, the maximal values of the temperature, pressure and current density on the anode surface are departing from the arc centreline.
文摘Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation, momentum conservation equations, energy conservation equations, generalized ohm's law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.
文摘To improve the limiting current interruption capability and minimizing vacuum interrupter with axial magnetic field （AMF） electrodes, it is significant to investigate the vacuum arc behaviours between the contacts. AMF distributions of the slot type electrodes were studied by both numerical analysis and experiments. Furthermore, the behaviours of vacuum arcs for different parameters of the slot type AMF electrodes were investigated by using high-speed CCD camera. The influences of gap distance, contact diameter and phase shift time between AMF and arc current on the vacuum arc were investigated. The results provide a reference for research and development of vacuum interrupters with slot type or other types of AMF electrode.
基金supported by the National Key Basic Research Program of China(973 Program) 2015CB251002National Natural Science Foundation of China under Grant 51521065, 51577145,51377128,51323012,51607135+3 种基金Program of State Grid Electrical Power Research Institute GY71-14-004the Science and Technology Project Funds of the Grid State Corporation(Medium voltage DC distribution protection) (SGSNKYOOKJJS1501564)the Science and Technology Project Funds of Hubei Electric Power Company(SGRIZLKJ (2016)325)State Key Laboratory of Electrical Insulation and Power Equipment(EIPE17305)
文摘After current zero,which is the moment when the vacuum circuit breaker interrupts a vacuum arc,sheath development is the first process in the dielectric recovery process.An axial magnetic field（AMF） is widely used in the vacuum circuit breaker when the high-current vacuum arc is interrupted.Therefore,it is very important to study the influence of different AMF amplitudes on the sheath development.The objective of this paper is to study the influence of different AMF amplitudes on the sheath development from a micro perspective.Thus,the particle in cell-Monte Carlo collisions（PIC-MCC） method was adopted to develop the sheath development model.We compared the simulation results with the experimental results and then validated the simulation.We also obtained the speed of the sheath development and the energy density of the ions under different AMF amplitudes.The results showed mat the larger the AMF amplitudes are,the faster the sheath develops and the lower the ion energy density is,meaning the breakdown is correspondingly more difficult.
基金supported by National Natural Science Foundation of China (Nos.50907045, 50707022)the Doctoral Fund of the Ministry of Education of China (Nos.200806981052, 20090201110015)
文摘Characteristics of the arc voltage under different profiles of axial magnetic field were investigated experimentally in a detachable vacuum chamber with five pairs of specially designed electrodes generating both bell-shaped and saddle-shaped magnetic field profile. The arc column and cathode spot images were photographed by a high speed digital camera. The dependence of the arc voltage on arcing evolution is analyzed. It is indicated that the axial magnetic field profile could affect the arc behaviors significantly, and the arc voltage is closely related to the arc light intensity.
基金Project supported by the National Natural Science Foundation of China （Grant No 10347009） and the Science Foundation of Education Bureau of Sichuan Province, China （Grant No 2003B019）.
文摘A helix type slow wave structure filled with plasma is immersed in a strong longitudinal magnetic field. Taking into account the effect of the plasma and the dielectric, the system is separated radially into three regions. By means of the sheath model and Maxwell equation, the distribution of the electromagnetic field is established. Using the boundary conditions of each region, the dispersion relation of the slow wave structure is derived. The trend of change for the radial profile of the axial electric field is analysed respectively in different plasma densities, plasma column radius and dielectric constant by numerical computation. Some useful results are obtained on the basis of the discussion.
文摘We consider the radiation from the beam electrons traveling in a strong uniform axial magnetic field and an axial alternating electric field of wavelength Aw generated by a voltage-supplied pill-box cavity. The beam electrons emit genuine laser radiation that propagates only in the axial direction through free-electron two- quantum Stark radiation. We find that laser radiation takes place only at the expense of the axial kinetic energy when Aw 〈〈 c/（ωc/γ）, where ωc/γ is the relativistic electron--cyclotron frequency. We formulate the laser power based on quantum-wiggler electrodynamics, and envision a laser of length lore with estimated power 0.1 GW/（kA） in the 10-4 cm wavelength range.
基金supported by the National Natural Science Foundation of China(Grant Nos.11175024,11375031,and 11505013)the Beijing Natural Science Foundation of China(Grant No.KZ201510015014)the Beijing Municipal Natural Science Foundation,China(Grant No.4162024)
文摘The modulation of absorption manner in helicon discharge by changing the profile of low axial magnetic field is explored experimentally in this work. The experiments are carried out in Boswell-type antenna driven by 13.56-MHz power source in 0.35-Pa argon environment. The peak of the external non-uniform magnetic field （Bex） along the axis is observed in a range from 0 Gs to 250 Gs （1 Gs=10^-4 T）, where the electron density varies from 0.5×10^16 m^-3 to 9×10^16 m^-3. When Bex is located near the tube upper end sealed by a dielectric plate, or near the tube bottom end connected with a diffusion chamber, the plasmas are centralized in the tube in the former case while the strong luminance appears between the edge of the tube and the axial line in the latter case. When Bex is located in the middle of the antenna, moreover, an effective resistance （Reff） peak appears apparently with increasing magnetic field. The glow moves toward first the edge of the tube and then the two antenna legs as the magnetic field increases. The discharge in this case is caused by the absorption of Trivelpiece-Gould （TG） wave. It is suggested that Bex is located in the middle of the antenna to obtain a higher efficiency of power transfer.
基金supported by National Natural Science Foundation of China (Nos.50876101,11035005)the Science Instrument Foundation of CAS
文摘The effect of an axial magnetic field （AMF） on an old xenon short-arc lamp is experimentally investigated in this work. As the AMF increases up to 18 roT, the visible radiation power and electric power ascend more than 80% and 70% respectively, and the radiation efficiency is improved by 23% for the best increment at 12 mT AMF. The measurement of radiation intensity shows that the increment of radiation intensity comes mostly from the plasma area close to the cathode tip, and partially from the other area of the arc column. Successive images of the arc indicate that the arc column not only rotates about its axis, but revolves around the axis of electrodes with the AMF. The arc column structure is constricted, distorted and elongated as the AMF increases. It is suggested that the improvements of the radiation intensity and radiation efficiency are attributed to the constriction of the arc column, which is mainly induced by the enhanced cathode jet.
基金supported by National Natural Science Foundation of China (No.50707022)Program for New Century Excellent Talents in University of China (No.NCET-06-0830)
文摘Effect of the axial magnetic field （AMF） on resisting the constriction of a highcurrent vacuum arc is studied in this paper. Two typical AMF distributions were investigated, i.e., the traditional bell-shaped AMF, and the saddle-shaped AMF. Experiments were conducted in a detachable vacuum chamber with arms arc current in the range of 10 kA to 25 kA. The arc column was photographed by a high-speed digital camera with an exposure time of 2 microseconds. The constriction of the vacuum arc was compared by processing the images of the arc column under the two different field configurations and numerically determining the dimensions of the arc column near the electrodes. It was also confirmed that the AMF distribution had a significant influence on its effectiveness in resisting arc constriction. of the arc is more influential than that at the Furthermore, the AMF strength near the periphery centre of the electrodes in resisting arc constriction.
文摘Recent results on the distribution of vacuum arc cathode spots （CSs） in nonuniform axial magnetic field （AMF） are presented. Based on previous studies, we deem that two contrary influences of AMF, inward effect and outward effect, are attributed to CSs distribution. With this notion, we have analyzed the controlling effectiveness of nonuniform AMF on CSs distribution. Experiments were conducted in a detachable vacuum chamber with iron-style AMF electrodes. Images of vacuum arc column and the distribution of CSs were photographed with a high-speed charge coupled device （CCD） camera. Experimental results agreed well with the theoretical analysis.
基金supported by National Natural Science Foundation of China(Nos.U1866202 and 51877164)State Key Laboratory of Electrical Insulation and Power Equipment Fund(No.EIPE19128)。
文摘As the main source of the vacuum arc plasma,cathode spots(CSs)play an important role on the behaviors of the vacuum arc.Their characteristics are affected by many factors,especially by the magnetic field.In this paper,the characteristics of the plasma jet from a single CS in vacuum arc under external axial magnetic field(AMF)are studied.A multi-species magneto-hydro-dynamic(MHD)model is established to describe the vacuum arc.The anode temperature is calculated by the anode activity model based on the energy flux obtained from the MHD model.The simulation results indicate that the external AMF has a significant effect on the characteristic of the plasma jet.When the external AMF is high enough,a bright spot appears on the anode surface.This is because with a higher AMF,the contraction of the diffused arc becomes more obvious,leading to a higher energy flux to the anode and thus a higher anode temperature.Then more secondary plasma can be generated near the anode,and the brightness of the‘anode spot’increases.During this process,the arc appearance gradually changes from a cone to a dumbbell shape.In this condition,the arc is in the diffuse mode.The appearance of the plasma jet calculated in the model is consistent with the experimental results.
文摘Cherenkov free electron laser(CFEL) is simulated numerically by using the single particle method to optimize the electron beam. The electron beam is assumed to be moving near the surface of a flat dielectric slab along a growing radiation. The set of coupled nonlinear differential equations of motion is solved to study the electron dynamics. For three sets of parameters, in high power CFEL, it is found that an axial magnetic field is always necessary to keep the electron beam in the interaction region and its optimal strength is reported for each case. At the injection point, the electron beam’s distance above the dielectric surface is kept at a minimum value so that the electrons neither hit the dielectric nor move away from it to the weaker radiation fields and out of the interaction region. The optimal electron beam radius and current are thereby calculated. This analysis is in agreement with two previous numerical studies for a cylindrical waveguide but is at odds with analytical treatments of a flat dielectric that does not use an axial magnetic field. This is backed by an interesting physical reasoning.
基金Project supported by the State Key Lab of Power Systems,China (Grant No. SKLD09KM06)
文摘The solutions to the electromagnetic field excited by a long axial current outside a conductive and magnetic cylindrical shell of finite length are studied in this paper. The more accurate analytical solutions are obtained by solving the proper boundary value problems by the separation variable method. Then the solutions are simplified according to asymptotic formulas of Bessel functions. Compared with the accurate solutions, the simplified solutions do not contain the Bessel functions and the inverse operation of the singular matrix, and can be calculated out fast by computers. The simplified solutions are more suitable for the cylindrical shell of high permeability and conductivity excited by a high frequency source. Both of the numerical results and the physical experimental results validate the simplified solutions obtained.
文摘As one of the relativistic electron tubes having compact configuration and high efficient output, the relativistic magnetron with direct axial radiation is very attractive in pulsed power and high power microwave fields for industrial and military applications. In this paper, the experimental investigation of a relativistic magnetron with axial TE11 mode radiation is reported. Under a total length of - 0.3 m, volume of - 0.014 m3, working at an applied voltage of 508 kV and a magnetic field of - 0.31 T, the relativistic magnetron radiates a microwave of 540 MW with the TE11 mode at 2.35 GHz in the axial direction. The power conversion efficiency is 15.0%. After a lot of shots, the detected amplitudes of microwaves are nearly the same. The fluctuations of wave amplitudes are less than 0.3 dB.
文摘In order to master the magnetic field distribution of submarines in the air completely and exactly and study the magnetic stealthy performance of submarine,a mathematic model of submarine magnetic field extrapolation is built based on the boundary element method(BEM).An experiment is designed to measure three components of magnetic field on the envelope surface surrounding a model submarine.The data in different heights above the model submarine are obtained by use of tri-axial magnetometers.The results show that this extrapolation model has good stabilities and high accuracies compared the measured data with the extrapolated data.Moreover,the model can reflect the submarine magnetic field distribution in the air exactly,and is valuable in practical engineering.
