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RSS2009 Vol. 21, No. 04
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Design of external-wave and particle modules for 3D full electromagnetic and PIC simulation software
2009,
21.
Abstract:
The algorithms of external-wave and particle modules were introduced for the 3D full electromagnetic and PIC simulation software. External-wave boundary module was studied, including coaxial-line, rectangular and cylindrical waveguide. The transmission characteristics were calculated and analyzed, including TEM in coaxial-line, TE10 in rectangular waveguide and TM10 in cylindrical waveguide. Particle boundary module was also studied, including particle emission and absorption. A coaxial diode was test which was designed for MILO. Its emission characteristic and input power of external-wave were studied and analyzed at different voltages. The simulated results demonstrated that electrons would show three different stage features: radial movement, axial drift, and drifting al
The algorithms of external-wave and particle modules were introduced for the 3D full electromagnetic and PIC simulation software. External-wave boundary module was studied, including coaxial-line, rectangular and cylindrical waveguide. The transmission characteristics were calculated and analyzed, including TEM in coaxial-line, TE10 in rectangular waveguide and TM10 in cylindrical waveguide. Particle boundary module was also studied, including particle emission and absorption. A coaxial diode was test which was designed for MILO. Its emission characteristic and input power of external-wave were studied and analyzed at different voltages. The simulated results demonstrated that electrons would show three different stage features: radial movement, axial drift, and drifting al
2009,
21.
Abstract:
According to theoretical analysis of the slow-wave structure(SWS), the parameters of SWS, the cathode and the anode are chosen. A new type X-band magnetically insulated line oscillator(MILO) has been designed using the advantages of both tapered MILO and loadlimited MILO. Through numerical simulations by a 2.5-D PIC code, the impacts of several structure parameters of MILO on its output power are investigated. High power microwave is generated from the optimized MILO by simulation with the average output power of 2.83 GW, the frequency of 8.2 GHz and the efficiency of 12.9%, when the beam voltage is 510 kV and current is 43 kA．
According to theoretical analysis of the slow-wave structure(SWS), the parameters of SWS, the cathode and the anode are chosen. A new type X-band magnetically insulated line oscillator(MILO) has been designed using the advantages of both tapered MILO and loadlimited MILO. Through numerical simulations by a 2.5-D PIC code, the impacts of several structure parameters of MILO on its output power are investigated. High power microwave is generated from the optimized MILO by simulation with the average output power of 2.83 GW, the frequency of 8.2 GHz and the efficiency of 12.9%, when the beam voltage is 510 kV and current is 43 kA．
2009,
21.
Abstract:
By way of numerical analysis, microwave generation characteristics of bifrequency magnetically insulated transmission line oscillators (BFMILOs) with azimuthal partition proportions of 1∶1, 1∶2, 1∶3, 2∶1 and 3∶1 are investigated. The microwave field distributions, the phasespace of electrons, the output microwave power and microwave frequencies as the function of angle on the hotcavity condition are obtained. In order to make comparison, two conventional MILO with two kinds of cavitydepth corresponding to the BFMILO are simulated and their simulation results are presented. The numerical study further shows the rule that the interaction between electron beam and microwave in BFMILO is separate in different particular partition, and it makes clear the mechanism of high power microwa
By way of numerical analysis, microwave generation characteristics of bifrequency magnetically insulated transmission line oscillators (BFMILOs) with azimuthal partition proportions of 1∶1, 1∶2, 1∶3, 2∶1 and 3∶1 are investigated. The microwave field distributions, the phasespace of electrons, the output microwave power and microwave frequencies as the function of angle on the hotcavity condition are obtained. In order to make comparison, two conventional MILO with two kinds of cavitydepth corresponding to the BFMILO are simulated and their simulation results are presented. The numerical study further shows the rule that the interaction between electron beam and microwave in BFMILO is separate in different particular partition, and it makes clear the mechanism of high power microwa
2009,
21.
Abstract:
A novel relativistic backward-wave oscillator(RBWO) is introduced with two kinds of slow wave structure separated by a tapered waveguide. It could obtain an output of C-band and X-band microwave simultaneously by means of a single electron beam. A 2.5-D full electro-magnetic numerical simulation is conducted by using Karat code at diode voltage of 1 MV, beam current of 8 kA, and guiding magnetic field of 3 T. A microwave pulse of TEM mode with power of 1.08 GW and an efficiency of 15% is obtained. Output frequencies are 5.42 GHz and 9.58 GHz respectively with an amplitude difference of 2.17 dB.
A novel relativistic backward-wave oscillator(RBWO) is introduced with two kinds of slow wave structure separated by a tapered waveguide. It could obtain an output of C-band and X-band microwave simultaneously by means of a single electron beam. A 2.5-D full electro-magnetic numerical simulation is conducted by using Karat code at diode voltage of 1 MV, beam current of 8 kA, and guiding magnetic field of 3 T. A microwave pulse of TEM mode with power of 1.08 GW and an efficiency of 15% is obtained. Output frequencies are 5.42 GHz and 9.58 GHz respectively with an amplitude difference of 2.17 dB.
2009,
21.
Abstract:
The gain of the open-ended rectangular waveguide was studied and the effects of flange on the gain of waveguide were discussed. The gain of BJ100 was calculated by an electromagnetic field simulation code. It is found that the period of the gain fluctuating with waveguide length is half wavelength. Then in the simulation, the outer wall of the waveguide was pasted with absorber to eliminate the effects of flange on the gain. The numerical simulation shows that this method weakens or even eliminates the dependence of gain on frequency, and the major lobe of the directional pattern becomes much wider with a peak in the center.
The gain of the open-ended rectangular waveguide was studied and the effects of flange on the gain of waveguide were discussed. The gain of BJ100 was calculated by an electromagnetic field simulation code. It is found that the period of the gain fluctuating with waveguide length is half wavelength. Then in the simulation, the outer wall of the waveguide was pasted with absorber to eliminate the effects of flange on the gain. The numerical simulation shows that this method weakens or even eliminates the dependence of gain on frequency, and the major lobe of the directional pattern becomes much wider with a peak in the center.
2009,
21.
Abstract:
This paper derives the dispersion equation and the linear growth rate formula of the coaxial relativistic baorward-wave oscillator(RBWO) according to the linear theory. The effects of the ripple period and ripple depth on the linear growth rate of the coaxial RBWO are presented. It is found that when the ripple period decreases or the ripple depth increases in a certain range, the phase velocity of the microwave decreases but the linear growth rate increases.
This paper derives the dispersion equation and the linear growth rate formula of the coaxial relativistic baorward-wave oscillator(RBWO) according to the linear theory. The effects of the ripple period and ripple depth on the linear growth rate of the coaxial RBWO are presented. It is found that when the ripple period decreases or the ripple depth increases in a certain range, the phase velocity of the microwave decreases but the linear growth rate increases.
2009,
21.
Abstract:
This paper presents high frequency characteristics analysis on an open input cavity of an S-band relativistic klystron amplifier and the optimization of the cavity geometry. Cold test on the high frequency parameters of the fabricated cavity is performed, and experimental results agree well with that of high frequency analysis. A three-dimension fully electromagnetic particle-in-cell(PIC) code is used to simulate the absorption of the injected microwave and the fundamental harmonic modulated current while the electron beams propagating the input cavity gap. The simulated results show that the cavity matches with the input waveguide and the whole energy of the driven microwave is absorbed by electron beams. The depth of the fundamental harmonic modulated current is about 13% at 37 cm downst
This paper presents high frequency characteristics analysis on an open input cavity of an S-band relativistic klystron amplifier and the optimization of the cavity geometry. Cold test on the high frequency parameters of the fabricated cavity is performed, and experimental results agree well with that of high frequency analysis. A three-dimension fully electromagnetic particle-in-cell(PIC) code is used to simulate the absorption of the injected microwave and the fundamental harmonic modulated current while the electron beams propagating the input cavity gap. The simulated results show that the cavity matches with the input waveguide and the whole energy of the driven microwave is absorbed by electron beams. The depth of the fundamental harmonic modulated current is about 13% at 37 cm downst
2009,
21.
Abstract:
An L-band 10 MW peak power, 150 kW average power multi-beam klystron(MBK) is studied．High quality multiple paracial electron optics system axis are achieved in a uniform, multi-lens magnetic field focusing system. The non-linear calculation of beam-wave interaction is carried for the L-band MBK with six electron beams and six coaxial cavities including a second harmonic cavity. The results show that the multi-beam klystron can produce an output peak power of more than 10 MW, an efficiency of more than 65% and a gain of more than 45 dB with a beam voltage of 115 kV and a beam current of 132 A．
An L-band 10 MW peak power, 150 kW average power multi-beam klystron(MBK) is studied．High quality multiple paracial electron optics system axis are achieved in a uniform, multi-lens magnetic field focusing system. The non-linear calculation of beam-wave interaction is carried for the L-band MBK with six electron beams and six coaxial cavities including a second harmonic cavity. The results show that the multi-beam klystron can produce an output peak power of more than 10 MW, an efficiency of more than 65% and a gain of more than 45 dB with a beam voltage of 115 kV and a beam current of 132 A．
2009,
21.
Abstract:
An L-band relativistic backward wave oscillator with coaxial extractor is investigated using the KARAT 2.5 D particle simulation code. Detailed beam-wave physical interaction in the oscillator are presented. Typical simulation results are that, under the magnetic field of 1.0 T, an L-band microwave with an average output power of 2.2 GW is obtained for 700 keV/10 kA electron beam, and the efficiency is over 30%. The optimized electromagnetic structure of the device is Φ100 mm×520 mm.
An L-band relativistic backward wave oscillator with coaxial extractor is investigated using the KARAT 2.5 D particle simulation code. Detailed beam-wave physical interaction in the oscillator are presented. Typical simulation results are that, under the magnetic field of 1.0 T, an L-band microwave with an average output power of 2.2 GW is obtained for 700 keV/10 kA electron beam, and the efficiency is over 30%. The optimized electromagnetic structure of the device is Φ100 mm×520 mm.
2009,
21.
Abstract:
A high energy density midium-high voltage pulse forming network(PFN) was designed with low self-inductance ceramic capacitors. Each capacitor has a measured capacitance of around 1.7 nF. The capacitors are made from a very high dielectric constant barium titanate dielectric mix, normally used to make high-voltage capacitors, and are 6 cm in diameter and 4 cm in thickness. Electrical strength tests carried out on the tiles has shown that the tiles can withstand an electric stress of at least 50 kV, provided that the tiles are submerged in transformer oil. The experimental results indicate that the rise time of the high voltage pulse is less than 40 ns, the pulse width is about 220 ns when the matched load is 1 Ω for flat(single-layered) and cuboid(double-layered) 6-line L-C PFNs. The cuboi
A high energy density midium-high voltage pulse forming network(PFN) was designed with low self-inductance ceramic capacitors. Each capacitor has a measured capacitance of around 1.7 nF. The capacitors are made from a very high dielectric constant barium titanate dielectric mix, normally used to make high-voltage capacitors, and are 6 cm in diameter and 4 cm in thickness. Electrical strength tests carried out on the tiles has shown that the tiles can withstand an electric stress of at least 50 kV, provided that the tiles are submerged in transformer oil. The experimental results indicate that the rise time of the high voltage pulse is less than 40 ns, the pulse width is about 220 ns when the matched load is 1 Ω for flat(single-layered) and cuboid(double-layered) 6-line L-C PFNs. The cuboi
2009,
21.
Abstract:
With the complementary antenna theory, this paper deduced the resonant frequencies of narrow slots. When the length of a vacuum slot is less than 5 times of the incident wavelength and the deviation angle of radiation relative to the perpendicular direction is less than 30°, the radiation of the slot can be explained by that of the dipole antenna, and resonances occurrs when the slot length equals to half wavelength. The dielectric slot can be equivalent to a microstrip and printed antenna with a depth half that of the slot. The theory expression matches the simulation results well with relative deviation below 5%. A further analysis of the coupling performance of the microwave-slot array indicates that the complementary antenna theory applies well in the study of microwave-slot coupling.
With the complementary antenna theory, this paper deduced the resonant frequencies of narrow slots. When the length of a vacuum slot is less than 5 times of the incident wavelength and the deviation angle of radiation relative to the perpendicular direction is less than 30°, the radiation of the slot can be explained by that of the dipole antenna, and resonances occurrs when the slot length equals to half wavelength. The dielectric slot can be equivalent to a microstrip and printed antenna with a depth half that of the slot. The theory expression matches the simulation results well with relative deviation below 5%. A further analysis of the coupling performance of the microwave-slot array indicates that the complementary antenna theory applies well in the study of microwave-slot coupling.
2009,
21.
Abstract:
Coaxial vircator with beam premodulation is analyzed by solving Green’s function, and the relationships of beamwave conversion efficiency to premodulation depth and frequency are obtained. Analysis results show that beam-wave conversion efficiency is in direct proportion to second power of premodulation depth for the same injecting beam, and there is a certain premodulation frequency corresponding to a maximal efficiency for every injecting beam and beam-wave interaction area combination. Finally, enhancing premodulation depth and choosing a reasonable premodulation frequency as efficacious ways to improve beamwave conversion efficiency are suggested．
Coaxial vircator with beam premodulation is analyzed by solving Green’s function, and the relationships of beamwave conversion efficiency to premodulation depth and frequency are obtained. Analysis results show that beam-wave conversion efficiency is in direct proportion to second power of premodulation depth for the same injecting beam, and there is a certain premodulation frequency corresponding to a maximal efficiency for every injecting beam and beam-wave interaction area combination. Finally, enhancing premodulation depth and choosing a reasonable premodulation frequency as efficacious ways to improve beamwave conversion efficiency are suggested．
2009,
21.
Abstract:
Seeking for the criterion of the least sample of microwave effects experiment, the research work between sample effect probability and collectivity effect probability is developed by the interval estimating. The Bernoulli distribution of a single microwave effect data is convered to the beta distribution, then expressed by the fractile of the F distribution, so the relational expression relating experimental sample, confidence level, sample effect probability and the collectivity effect probability is derived. The computing result indicates that it is comparatively reasonable when the sample of microwave effects experiment is 10, thus, the confidence lower limit of collectivity effect probability is about 51.6% in 80％confidence level when the sample effect probability is 70％. In this way
Seeking for the criterion of the least sample of microwave effects experiment, the research work between sample effect probability and collectivity effect probability is developed by the interval estimating. The Bernoulli distribution of a single microwave effect data is convered to the beta distribution, then expressed by the fractile of the F distribution, so the relational expression relating experimental sample, confidence level, sample effect probability and the collectivity effect probability is derived. The computing result indicates that it is comparatively reasonable when the sample of microwave effects experiment is 10, thus, the confidence lower limit of collectivity effect probability is about 51.6% in 80％confidence level when the sample effect probability is 70％. In this way
2009,
21.
Abstract:
Air breakdown caused by repetition frequency high power microwave (HPM) has been investigated. The electronic relaxation process affected by repetition frequency pulses has been analyzed, and variations regulation of the electron temperature and free electron density pulsein interval time has been studied, It is found that the electron temperature relaxation time is far less than the electron density relaxation time. This paper analyzes the attachment and recombination effects in the electronic relaxation process, and present the occurrence condition of air breakdown caused by repetition frequency HPM, and the electronic density equation of the air breakdown.
Air breakdown caused by repetition frequency high power microwave (HPM) has been investigated. The electronic relaxation process affected by repetition frequency pulses has been analyzed, and variations regulation of the electron temperature and free electron density pulsein interval time has been studied, It is found that the electron temperature relaxation time is far less than the electron density relaxation time. This paper analyzes the attachment and recombination effects in the electronic relaxation process, and present the occurrence condition of air breakdown caused by repetition frequency HPM, and the electronic density equation of the air breakdown.
2009,
21.
Abstract:
A triangle-grid radial-line helical rectangular array antenna was proposed. Based on the backgrounds and the principle of the array antenna, the 8-element triangle-grid radial-line helical rectangular array antenna was studied by the numerical simulation at the central frequency of 4.0 GHz and experiments. Experimental results indicate that: at the central frequency of 4.0 GHz, the power gain is 15.3 dB, the axial ratio is 1.58 at the normal direction, the voltage standing wave ratio(VSWR) is 1.3 and the aperture efficiency is 86%. In the range of 3.8 GHz to 4.2 GHz, the power gain is above 14.9 dB, the axial ratio is below 1.7 and the VSWR is below 1.6．
A triangle-grid radial-line helical rectangular array antenna was proposed. Based on the backgrounds and the principle of the array antenna, the 8-element triangle-grid radial-line helical rectangular array antenna was studied by the numerical simulation at the central frequency of 4.0 GHz and experiments. Experimental results indicate that: at the central frequency of 4.0 GHz, the power gain is 15.3 dB, the axial ratio is 1.58 at the normal direction, the voltage standing wave ratio(VSWR) is 1.3 and the aperture efficiency is 86%. In the range of 3.8 GHz to 4.2 GHz, the power gain is above 14.9 dB, the axial ratio is below 1.7 and the VSWR is below 1.6．
2009,
21.
Abstract:
The transmission of wave packets in a potential well was analyzed by the quantum effect theory. The occurrence condition of resonant transmission was obtained by classified discussion.The comparison of it with results of the numerical simulation and coupling experiment shows a general agreement. That is, the resonant enhancement will take place if the slot side length is an integral multiple of the microwave half-wavelength, when the direction of the incident electric field is perpendicular to the long side of the slot. In the meantime, it would help to illuminate strong couplings in high power microwave effect experiments on complicated electronic systems.
The transmission of wave packets in a potential well was analyzed by the quantum effect theory. The occurrence condition of resonant transmission was obtained by classified discussion.The comparison of it with results of the numerical simulation and coupling experiment shows a general agreement. That is, the resonant enhancement will take place if the slot side length is an integral multiple of the microwave half-wavelength, when the direction of the incident electric field is perpendicular to the long side of the slot. In the meantime, it would help to illuminate strong couplings in high power microwave effect experiments on complicated electronic systems.
2009,
21.
Abstract:
In the experiments of high power microwave(HPM) effects on microwave components, four kinds of effect phenomenon were observed, including the changes of microwave pulse power, width, phase and transient HPM suppression. Based on these phenomena, mathematical models of four effect parameters were built. According to the variables separation method, the method of weighted function was brought forward and used in decomposing the multidimensional function. Results show that the way is effective on mathematic models, which were built of finite experimental data. In addition, several important means of data processing were introduced. Finally, the application of the new method to effective evaluation of TR tube was given．
In the experiments of high power microwave(HPM) effects on microwave components, four kinds of effect phenomenon were observed, including the changes of microwave pulse power, width, phase and transient HPM suppression. Based on these phenomena, mathematical models of four effect parameters were built. According to the variables separation method, the method of weighted function was brought forward and used in decomposing the multidimensional function. Results show that the way is effective on mathematic models, which were built of finite experimental data. In addition, several important means of data processing were introduced. Finally, the application of the new method to effective evaluation of TR tube was given．
2009,
21.
Abstract:
A novel method for measuring the complex permittivity of dielectric plates is proposed by using TM0mn modes in a closed cylindrical resonant cavity. The analysis based on the Ritz-Galerkin method, mode matching technique and transmission-mode quality factor measurement method is performed, and the formulas for calculating the complex permittivity are developed. Finally, a sweep-frequency measurement of the complex permittivity is conducted on high molecular weight polyethylene(HMWPE) using an Angilent vector network analyzer. Within the frequency range of 3~6 GHz, the relative permittivity and loss tangent of HMWPE turn out to be 2.30±0.05 and (1.8~2.0)×10-4, respectively.
A novel method for measuring the complex permittivity of dielectric plates is proposed by using TM0mn modes in a closed cylindrical resonant cavity. The analysis based on the Ritz-Galerkin method, mode matching technique and transmission-mode quality factor measurement method is performed, and the formulas for calculating the complex permittivity are developed. Finally, a sweep-frequency measurement of the complex permittivity is conducted on high molecular weight polyethylene(HMWPE) using an Angilent vector network analyzer. Within the frequency range of 3~6 GHz, the relative permittivity and loss tangent of HMWPE turn out to be 2.30±0.05 and (1.8~2.0)×10-4, respectively.
2009,
21.
Abstract:
The basic concept of the integrated circuit high power microwave(HPM) vulnerability was introduced as well as the main establishment processes of an integrated circuit high power microwave vulnerability estimation model. It is demonstrated by an example that the neural network is an effective method to evaluate high power microwave vulnerability effects of the integrated circuit.
The basic concept of the integrated circuit high power microwave(HPM) vulnerability was introduced as well as the main establishment processes of an integrated circuit high power microwave vulnerability estimation model. It is demonstrated by an example that the neural network is an effective method to evaluate high power microwave vulnerability effects of the integrated circuit.
2009,
21.
Abstract:
This paper studies the termination responses of a shielded cable within a cavity with slot under external electromagnetic field, using a mixed method combining the finite difference time domain(FDTD)method with the transmission line model of the shielded cable. The excitation fields of the cable are computed firstly with the FDTD method, and then the responses of the terminations are computed using the transmission line model. The mixed method requires small memory and computation quantity with ease of use. The study shows that the shield of the cable has good shielding capabilities for external electromagnetic interference.
This paper studies the termination responses of a shielded cable within a cavity with slot under external electromagnetic field, using a mixed method combining the finite difference time domain(FDTD)method with the transmission line model of the shielded cable. The excitation fields of the cable are computed firstly with the FDTD method, and then the responses of the terminations are computed using the transmission line model. The mixed method requires small memory and computation quantity with ease of use. The study shows that the shield of the cable has good shielding capabilities for external electromagnetic interference.
2009,
21.
Abstract:
Transmission line method is extended to include multi-mode transverse electric cavity modes which are introduced by aperture coupling and it is used to analyze the coupling effectiveness of double layer rectangular enclosure with aperture to the wide band high power microwave electromagnetic pulse. The electric shielding effectiveness of single layer enclosure with aperture is compared with that of double layer enclosure with apertures. The simulation results show that: shielding effectiveness can be improved greatly with double layer shielding and it is worse on the resonance frequency of cavity modes. On the condition of aperture-cavity resonance, shielding effectiveness drops significantly in the center of inner cavity. FDTD result is compare to the results of transmission line model. F
Transmission line method is extended to include multi-mode transverse electric cavity modes which are introduced by aperture coupling and it is used to analyze the coupling effectiveness of double layer rectangular enclosure with aperture to the wide band high power microwave electromagnetic pulse. The electric shielding effectiveness of single layer enclosure with aperture is compared with that of double layer enclosure with apertures. The simulation results show that: shielding effectiveness can be improved greatly with double layer shielding and it is worse on the resonance frequency of cavity modes. On the condition of aperture-cavity resonance, shielding effectiveness drops significantly in the center of inner cavity. FDTD result is compare to the results of transmission line model. F
2009,
21.
Abstract:
Based on the theory of mode coupling, the paper deduced the timedependent couplingwave equationd that the modes satisfy in tapering circular waveguide, and presented the expressions of coupling coefficients of the equations. The metallic wall loss was considered in the process. According to the equations, we write a code for simulation of the multimode transmission property in tapering circular waveguide. Firstly, using the code, mode loss in circular waveguide in THz region was computed.It is found that when studying the multimode transmission property in tapering circular waveguide,the effect of metallic wall impedance loss must be considered.Secondly,we analyzed mode coupling numerically. This attests to the existence of the coupling mechanism due to fininte conductivity of the meta
Based on the theory of mode coupling, the paper deduced the timedependent couplingwave equationd that the modes satisfy in tapering circular waveguide, and presented the expressions of coupling coefficients of the equations. The metallic wall loss was considered in the process. According to the equations, we write a code for simulation of the multimode transmission property in tapering circular waveguide. Firstly, using the code, mode loss in circular waveguide in THz region was computed.It is found that when studying the multimode transmission property in tapering circular waveguide,the effect of metallic wall impedance loss must be considered.Secondly,we analyzed mode coupling numerically. This attests to the existence of the coupling mechanism due to fininte conductivity of the meta
2009,
21.
Abstract:
A capacitor-loaded parallel plate transmission line model was introduced and its propagating characteristic was analyzed. The loaded capacitor’s distance was decreased to increase the upper limit of PFN’s cutoff frequency and to decrease the impedance dispersion. With the loss-line model, the reflection coefficient at PFN’s end was analyzed and the method to minimize this coefficient was researched. The magnetic coupling for series PFN was also researched and the influences of PFN’s parameters and their arrangement mode on pulse current were analyzed. Based on the technologies of series PFN and Tesla transformer, a 2 GW long-pulse generator was developed, with 300 kV output voltage, 110 ns pulse width and less than 10 ns rise time．
A capacitor-loaded parallel plate transmission line model was introduced and its propagating characteristic was analyzed. The loaded capacitor’s distance was decreased to increase the upper limit of PFN’s cutoff frequency and to decrease the impedance dispersion. With the loss-line model, the reflection coefficient at PFN’s end was analyzed and the method to minimize this coefficient was researched. The magnetic coupling for series PFN was also researched and the influences of PFN’s parameters and their arrangement mode on pulse current were analyzed. Based on the technologies of series PFN and Tesla transformer, a 2 GW long-pulse generator was developed, with 300 kV output voltage, 110 ns pulse width and less than 10 ns rise time．
2009,
21.
Abstract:
A simple, mobile and robust high power wideband source has been developed. It is comprised of a ring switch, a transmission line, and a conical antenna. The resonance is simulated by a finite difference time domain(FDTD) software. A wideband microwave is obtained with a radiation centered on 272 MHz ,and a percent bandwidth of about 13.5%. The resonance system employs a high power source to obtain a voltage-charging level of 71 kV in the switch. The experiment a results show that the radiation electric field is 8.58 kV/m at 3.3 m range, and the radiation is centered on 197 MHz with a percent bandwidth of about 24%.
A simple, mobile and robust high power wideband source has been developed. It is comprised of a ring switch, a transmission line, and a conical antenna. The resonance is simulated by a finite difference time domain(FDTD) software. A wideband microwave is obtained with a radiation centered on 272 MHz ,and a percent bandwidth of about 13.5%. The resonance system employs a high power source to obtain a voltage-charging level of 71 kV in the switch. The experiment a results show that the radiation electric field is 8.58 kV/m at 3.3 m range, and the radiation is centered on 197 MHz with a percent bandwidth of about 24%.
2009,
21.
Abstract:
A compact output switch for a water pulse forming line(PFL) ebeam accelerator was designed. The accelerator is of the helical coaxial PFL type, having impedance of 9 Ω, and charging voltage 1.2 MV, and outputs 600 kV, 100 ns on matched load. The length of PFL is 1.1 m, and diameter less than 35 cm. The output switch is of the simple self-breaking gas type, designed following these principles: (1) it’s field enhancement factor is 1.4, which makes it possible to have a near linear curve for SF6’s voltage-pressure curve; (2) field within the gap is 300 kV/cm, 3 times stronger than that along the insulator, which prevents surface flashover; (3) field at triple points is controlled within 30 kV/cm; (4) the volume of switch is minimized to enhance its mechanical strength. The lengh of switc
A compact output switch for a water pulse forming line(PFL) ebeam accelerator was designed. The accelerator is of the helical coaxial PFL type, having impedance of 9 Ω, and charging voltage 1.2 MV, and outputs 600 kV, 100 ns on matched load. The length of PFL is 1.1 m, and diameter less than 35 cm. The output switch is of the simple self-breaking gas type, designed following these principles: (1) it’s field enhancement factor is 1.4, which makes it possible to have a near linear curve for SF6’s voltage-pressure curve; (2) field within the gap is 300 kV/cm, 3 times stronger than that along the insulator, which prevents surface flashover; (3) field at triple points is controlled within 30 kV/cm; (4) the volume of switch is minimized to enhance its mechanical strength. The lengh of switc
2009,
21.
Abstract:
Increasing gain and radiant efficiency is one of the most important aims of the research on trantrent antenna. The energy array factor of transient radiation was deduced by setting the Gaussian pulse feeding waveform. The transient radiation characteristic of one dimension, symmetrical, and uniform array was analyzed. The radiated waveform of array is correlated with observational time and angle, transient characteristic is quite different from that of transient-free, time domain pattern is correlated with pulse width, and time domain array is scannable. The dielectric loaded antenna array were designed and simulated by using 3D time domain electromagnetic simulation software. The front peak electric field of antenna with dielectric is two times of antenna without dielectric, and the effec
Increasing gain and radiant efficiency is one of the most important aims of the research on trantrent antenna. The energy array factor of transient radiation was deduced by setting the Gaussian pulse feeding waveform. The transient radiation characteristic of one dimension, symmetrical, and uniform array was analyzed. The radiated waveform of array is correlated with observational time and angle, transient characteristic is quite different from that of transient-free, time domain pattern is correlated with pulse width, and time domain array is scannable. The dielectric loaded antenna array were designed and simulated by using 3D time domain electromagnetic simulation software. The front peak electric field of antenna with dielectric is two times of antenna without dielectric, and the effec
2009,
21.
Abstract:
Effect of gas flow velocity on repetitive operation performance was experimentally investigated for a spark gap switch with a compact gas blowing system, based on a compact repetitive Tesla transformer. The experimental results were presented and analyzed. The conclusions are shown as follows: (1) for a repetition rate lower than 50 Hz, the pulse-to-pulse instability (RMS) of the breakdown voltage of the spark gap switch is smaller than 5% and it is possible to spare a gas blowing system; (2) given a gas flow velocity, there exists a critical repetition rate for the stable operation of the spark gap switch; (3) for the repetitive operation of the switch in a given repetition rate, there exists an optimal fan frequency, which is linear with the repetition rate and can be determined by expe
Effect of gas flow velocity on repetitive operation performance was experimentally investigated for a spark gap switch with a compact gas blowing system, based on a compact repetitive Tesla transformer. The experimental results were presented and analyzed. The conclusions are shown as follows: (1) for a repetition rate lower than 50 Hz, the pulse-to-pulse instability (RMS) of the breakdown voltage of the spark gap switch is smaller than 5% and it is possible to spare a gas blowing system; (2) given a gas flow velocity, there exists a critical repetition rate for the stable operation of the spark gap switch; (3) for the repetitive operation of the switch in a given repetition rate, there exists an optimal fan frequency, which is linear with the repetition rate and can be determined by expe
2009,
21.
Abstract:
The theoretical calculation of Blumlein pulse forming line(PFL) is complicated and maybe inaccurate. It is often difficult to get reliable direct electrical measurements due to the scale of these machines. To determine exact parameters of the Blumlein type Spark-03 PFL, a finite element method was used. A 2-D axially symmetric model of a compact accelerator based on thd Blumlein line with water dielectric was established. The electric field distribution and capacitance of the accelerator were derived using the electric energy integral method. Result comparison among the calculation, theory and experiment show that the calculated values are closer to the experimental ones than the theoretical values are．
The theoretical calculation of Blumlein pulse forming line(PFL) is complicated and maybe inaccurate. It is often difficult to get reliable direct electrical measurements due to the scale of these machines. To determine exact parameters of the Blumlein type Spark-03 PFL, a finite element method was used. A 2-D axially symmetric model of a compact accelerator based on thd Blumlein line with water dielectric was established. The electric field distribution and capacitance of the accelerator were derived using the electric energy integral method. Result comparison among the calculation, theory and experiment show that the calculated values are closer to the experimental ones than the theoretical values are．
2009,
21.
Abstract:
A radial insulation structure used in an intense beam diode was introduced and the surface flashover across the oil-solid interface was studied. The geometry structure parameters were optimized by simulating the static electric field intensity distribution on the surface of the cone-shaped insulator. The experiment was done on a pulse power source with 40 ns pulse width and 100 Hz repetitive frequency. A bush-like streamer was observed on the insulator surface after 100 000 shots loaded in 18 months. The streamer root region of the insulator was severely carbonized and the breakdown and carbonization happened in the depth direction of the insulator, leading to the formation of pores. Based on the solid-liquid interface flashover mechanics, possible causes of flashover were discussed.
A radial insulation structure used in an intense beam diode was introduced and the surface flashover across the oil-solid interface was studied. The geometry structure parameters were optimized by simulating the static electric field intensity distribution on the surface of the cone-shaped insulator. The experiment was done on a pulse power source with 40 ns pulse width and 100 Hz repetitive frequency. A bush-like streamer was observed on the insulator surface after 100 000 shots loaded in 18 months. The streamer root region of the insulator was severely carbonized and the breakdown and carbonization happened in the depth direction of the insulator, leading to the formation of pores. Based on the solid-liquid interface flashover mechanics, possible causes of flashover were discussed.
2009,
21.
Abstract:
This paper has investigated the high voltage pulse on the lowimpedance load（19 Ω） generated by the pulse transformer driven by the electrically exploded opening switch. It has built a lump-parameter circuit model by the Ansoft Simplorer 7 code to simulate the circuit behavior and got the simulation results which agree with the experiment well. The preliminary investigation showed that the pulse transformer driven by the EEOS was impossible to generate super-high voltage pulse on low-impedance load, but the transformer could extend the pulse width obviously. This behavior has the potential to be used in the situation which needs long width voltage pulse．
This paper has investigated the high voltage pulse on the lowimpedance load（19 Ω） generated by the pulse transformer driven by the electrically exploded opening switch. It has built a lump-parameter circuit model by the Ansoft Simplorer 7 code to simulate the circuit behavior and got the simulation results which agree with the experiment well. The preliminary investigation showed that the pulse transformer driven by the EEOS was impossible to generate super-high voltage pulse on low-impedance load, but the transformer could extend the pulse width obviously. This behavior has the potential to be used in the situation which needs long width voltage pulse．
2009,
21.
Abstract:
Three coaxial peaking-chopping subnanosecond gas switches were designed,including two ring-ring electrodes and a sphere-ring electrode. Experimental researches on their operating characteristics were performed on a semiconductor opening switch-based pulse source respectively. Results show that the switch can work steadily at 1～500 Hz repetition rate, and can output a pulse with 400 ps rise time, 320 ps fall time, 460 ps width and 129.2 kV peak voltage, as the switch adopts the ring-ring electrodeⅡ. It is also revealed that gap size, gap pressure and repetition rate of the switches all have great effects on rise time, fall time, voltage range and repetition rate of output pulses. The subnanosecond gas switch has excellent operating characteristics when it operates at small gap (1～2 mm)
Three coaxial peaking-chopping subnanosecond gas switches were designed,including two ring-ring electrodes and a sphere-ring electrode. Experimental researches on their operating characteristics were performed on a semiconductor opening switch-based pulse source respectively. Results show that the switch can work steadily at 1～500 Hz repetition rate, and can output a pulse with 400 ps rise time, 320 ps fall time, 460 ps width and 129.2 kV peak voltage, as the switch adopts the ring-ring electrodeⅡ. It is also revealed that gap size, gap pressure and repetition rate of the switches all have great effects on rise time, fall time, voltage range and repetition rate of output pulses. The subnanosecond gas switch has excellent operating characteristics when it operates at small gap (1～2 mm)
2009,
21.
Abstract:
The circuit diagram of a 4-stage voltage transmission line transformer(TLT) is analyzed. The circuit is simplified by means of equivalent circuit, and the expression of the output waveform is derived. The low voltage test of the 4-stage TLT is developed, the result of which indicates the voltage ratio is about 4 and rise time 48 ns. The result of simulation with PSPICE is in good agreement with the test. With the same parameters, theoretical calculation of output voltage amplitude is 3.98 which corresponded to measured value 4. However, there is some discrepancy between calculated value of TLT’s rise time (12 ns) and measured value (48 ns).
The circuit diagram of a 4-stage voltage transmission line transformer(TLT) is analyzed. The circuit is simplified by means of equivalent circuit, and the expression of the output waveform is derived. The low voltage test of the 4-stage TLT is developed, the result of which indicates the voltage ratio is about 4 and rise time 48 ns. The result of simulation with PSPICE is in good agreement with the test. With the same parameters, theoretical calculation of output voltage amplitude is 3.98 which corresponded to measured value 4. However, there is some discrepancy between calculated value of TLT’s rise time (12 ns) and measured value (48 ns).
2009,
21.
Abstract:
This paper discusses the design feature of the repetitive Marx generator, and presents the electrostatic field in switch cavity. Based on the theoretic analysis and experimental research, a 12 stage repetitive Marx generator with inductive isolators has been developed recently, it is charged synchronously with positive and negative constant current. Elements of the Marx generator were compactly arranged to attain lower circuit inductance. Experiments show 532 kV output peak voltage with rise-time about 40 ns and the generator’s set-up time is about 32 ns. Filled with pure SF6 gas in switch cavity, the Marx generator works stably in the repetitive frequency of 1~50 Hz.
This paper discusses the design feature of the repetitive Marx generator, and presents the electrostatic field in switch cavity. Based on the theoretic analysis and experimental research, a 12 stage repetitive Marx generator with inductive isolators has been developed recently, it is charged synchronously with positive and negative constant current. Elements of the Marx generator were compactly arranged to attain lower circuit inductance. Experiments show 532 kV output peak voltage with rise-time about 40 ns and the generator’s set-up time is about 32 ns. Filled with pure SF6 gas in switch cavity, the Marx generator works stably in the repetitive frequency of 1~50 Hz.
