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RSS2018 Vol. 30, No. 8
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2018,
30: 081001.
doi: 10.11884/HPLPB201830.180020
Abstract:
In order to achieve the measurement of large-aperture mirrors with high precision, the stitching interferometer system is established, the whole surface is obtained. The basic theory of stitching measurement technology is to divide the whole test mirror into several parts, and then measure the surface of each part respectively, and finally stitch these surfaces of different parts together. In the process of stitching measurement, overlapping areas between different local surface shapes use mean method of fusing overlapping areas would reduce the high-frequency components. First of all, the original overlapping areas surface shape goes through the wavelet transformation, resulting in low frequency coefficients and high frequency coefficients; Then, low frequency coefficients and high frequency coefficients is determined by different fusion rules; in the end, Finally, overlapping area surface shape is obtained by wavelet inverse transformation. This paper discusses the stitching interferometer test on a 120 mm×40 mm rectangular reflection mirror, in which fusion of overlapping areas has average method as well as the proposed algorithm, and also uses power spectral density conduct an objective comparison on the fusion results. The result of this experiment shows that the proposed algorithm fusion has better effects to improves the retention of high-frequency than the conventional methods.
In order to achieve the measurement of large-aperture mirrors with high precision, the stitching interferometer system is established, the whole surface is obtained. The basic theory of stitching measurement technology is to divide the whole test mirror into several parts, and then measure the surface of each part respectively, and finally stitch these surfaces of different parts together. In the process of stitching measurement, overlapping areas between different local surface shapes use mean method of fusing overlapping areas would reduce the high-frequency components. First of all, the original overlapping areas surface shape goes through the wavelet transformation, resulting in low frequency coefficients and high frequency coefficients; Then, low frequency coefficients and high frequency coefficients is determined by different fusion rules; in the end, Finally, overlapping area surface shape is obtained by wavelet inverse transformation. This paper discusses the stitching interferometer test on a 120 mm×40 mm rectangular reflection mirror, in which fusion of overlapping areas has average method as well as the proposed algorithm, and also uses power spectral density conduct an objective comparison on the fusion results. The result of this experiment shows that the proposed algorithm fusion has better effects to improves the retention of high-frequency than the conventional methods.
2018,
30: 081002.
doi: 10.11884/HPLPB201830.170497
Abstract:
Aim at the change problem of output beam direction when using a rotated out-coupling mirror as the tunable element, a laser system with constant direction of the tuned output beam was designed by shifting the gain fiber position. According to the grating equation, the tunable mechanism of shifting gain fiber was analyzed. Further, the changes of gain linewidth with the fiber position and mode field radius were also analyzed by means of the coupling model of the output and feedback beams, which show that the gain linewidth of the output beams for the designed fiber laser was less than 0.2 nm. The experimental results show that the maximum output power is 470 mW at 1543.446 nm, with a slope efficiency of 23.9%. The experiment also shows that the wavelength tunable range is 36 nm, and the 3 dB linewidths in the whole tunable range are less than 0.08 nm.
Aim at the change problem of output beam direction when using a rotated out-coupling mirror as the tunable element, a laser system with constant direction of the tuned output beam was designed by shifting the gain fiber position. According to the grating equation, the tunable mechanism of shifting gain fiber was analyzed. Further, the changes of gain linewidth with the fiber position and mode field radius were also analyzed by means of the coupling model of the output and feedback beams, which show that the gain linewidth of the output beams for the designed fiber laser was less than 0.2 nm. The experimental results show that the maximum output power is 470 mW at 1543.446 nm, with a slope efficiency of 23.9%. The experiment also shows that the wavelength tunable range is 36 nm, and the 3 dB linewidths in the whole tunable range are less than 0.08 nm.
2018,
30: 081003.
doi: 10.11884/HPLPB201830.180079
Abstract:
In this paper, the normal single-mode fiber is pulled into microfiber by the method of carbon dioxide laser heating, wet method is used to transfer graphene and cover microfiber to form a composite waveguide. The light of different wavelengths enters the composite waveguide through the coupler, interacts with graphene in the form of evanescent waves, thus the research experiment of preferential absorption characteristic is carried out. When a short wave light was used as a pump light, changes in the long wave spectrum with the increase of incident intensity were measured, obtaining a modulation depth of about 3.5 dB, and a modulation efficiency of 0.62 dB·mW-1. When the long wave light was used as the pump light, the light transmittance of the short wave signal was measured to change by ~1.9%. The experimental results show that with the increase of the incident light intensity of the pump light at any wavelength, the composite waveguide exhibits its preferential absorption characteristics. In addition, when the long-wave and short-wave waves passed through the composite waveguide, the transmittance changes with the input power were tested, experiments show that the long-wavelength transmittance increases faster than the short-wavelength transmittance, and the corresponding theoretical analysis can be made from the two aspects of energy band and evanescent wave.
In this paper, the normal single-mode fiber is pulled into microfiber by the method of carbon dioxide laser heating, wet method is used to transfer graphene and cover microfiber to form a composite waveguide. The light of different wavelengths enters the composite waveguide through the coupler, interacts with graphene in the form of evanescent waves, thus the research experiment of preferential absorption characteristic is carried out. When a short wave light was used as a pump light, changes in the long wave spectrum with the increase of incident intensity were measured, obtaining a modulation depth of about 3.5 dB, and a modulation efficiency of 0.62 dB·mW-1. When the long wave light was used as the pump light, the light transmittance of the short wave signal was measured to change by ~1.9%. The experimental results show that with the increase of the incident light intensity of the pump light at any wavelength, the composite waveguide exhibits its preferential absorption characteristics. In addition, when the long-wave and short-wave waves passed through the composite waveguide, the transmittance changes with the input power were tested, experiments show that the long-wavelength transmittance increases faster than the short-wavelength transmittance, and the corresponding theoretical analysis can be made from the two aspects of energy band and evanescent wave.
2018,
30: 082001.
doi: 10.11884/HPLPB201830.180028
Abstract:
In order to overcome the randomness, abrasive waste and hydration layer of free abrasive polishing, a technology of bounded abrasive polishing for fused silica glass under anhydrous environment is proposed. A stable polishing wheel sintering process has been developed and applied to the polishing of fused silica glass. EDS energy spectrum analysis and XRD analysis of the processed products and the polishing wheel powder are carried out. The removal mechanism of consolidation abrasive polishing is preliminarily elaborated, and the effect of pressure and speed on the removal efficiency and surface roughness is explored from the macroscopic point of view. The experimental results show that: in the process, under normal force and shear force, the CeO2 abrasive reacts with the fused silica, CeO2 will bring SiO2 out of the glass, thus to achieve material removal; at the same time, influence of pressure and rotating speed on the processing efficiency does not follow the Preston formula, temperature rise and chip removal of the polishing wheel are the key factors determining the efficiency of removal.
In order to overcome the randomness, abrasive waste and hydration layer of free abrasive polishing, a technology of bounded abrasive polishing for fused silica glass under anhydrous environment is proposed. A stable polishing wheel sintering process has been developed and applied to the polishing of fused silica glass. EDS energy spectrum analysis and XRD analysis of the processed products and the polishing wheel powder are carried out. The removal mechanism of consolidation abrasive polishing is preliminarily elaborated, and the effect of pressure and speed on the removal efficiency and surface roughness is explored from the macroscopic point of view. The experimental results show that: in the process, under normal force and shear force, the CeO2 abrasive reacts with the fused silica, CeO2 will bring SiO2 out of the glass, thus to achieve material removal; at the same time, influence of pressure and rotating speed on the processing efficiency does not follow the Preston formula, temperature rise and chip removal of the polishing wheel are the key factors determining the efficiency of removal.
2018,
30: 082002.
doi: 10.11884/HPLPB201830.170493
Abstract:
The optical design software ZEMAX is used to simulate the imaging of a point source for Wolter microscope. Considering the imaging of geometrical optics only, three instances are considered, including the two surfaces coaxial and cofocal, non-coaxial, and coaxial but not confocal. The imaging of a point source is discussed respectively. The depth of focus and the depth of field are given. The imaging of a point source in different fields is also analyzed. It is concluded that Wolter microscope is very strict with the object distance and image distance. The influence of the two surfaces' non-coaxiality and non-confocality is much great on imaging. These results provides basis for imaging analysis of Wolter microscope.
The optical design software ZEMAX is used to simulate the imaging of a point source for Wolter microscope. Considering the imaging of geometrical optics only, three instances are considered, including the two surfaces coaxial and cofocal, non-coaxial, and coaxial but not confocal. The imaging of a point source is discussed respectively. The depth of focus and the depth of field are given. The imaging of a point source in different fields is also analyzed. It is concluded that Wolter microscope is very strict with the object distance and image distance. The influence of the two surfaces' non-coaxiality and non-confocality is much great on imaging. These results provides basis for imaging analysis of Wolter microscope.
2018,
30: 083001.
doi: 10.11884/HPLPB201830.170429
Abstract:
This paper presents the study of massively parallel simulation of multi-physics effect with electromagnetic pluses excitation using a high-performance computing scheme based on JAUMIN. Our in-house time-domain finite element parallel program JEMS-CDS-System is employed for simulating the electro-thermo-mechanical responses of bonding wire arrays and their highest temperatures and von Mises stress are captured and validated in comparison with those of the commercial simulator COMSOL. The thermo-mechanical responses of a part of SiP are simulated and parallel efficiency of our parallel program is assessed by the experiment of its strong parallel scalability. Our parallel program can reach a speedup of 6.095 and strong scalability efficiency of 38.1% on 1024 CPU cores.
This paper presents the study of massively parallel simulation of multi-physics effect with electromagnetic pluses excitation using a high-performance computing scheme based on JAUMIN. Our in-house time-domain finite element parallel program JEMS-CDS-System is employed for simulating the electro-thermo-mechanical responses of bonding wire arrays and their highest temperatures and von Mises stress are captured and validated in comparison with those of the commercial simulator COMSOL. The thermo-mechanical responses of a part of SiP are simulated and parallel efficiency of our parallel program is assessed by the experiment of its strong parallel scalability. Our parallel program can reach a speedup of 6.095 and strong scalability efficiency of 38.1% on 1024 CPU cores.
2018,
30: 083002.
doi: 10.11884/HPLPB201830.180050
Abstract:
The interaction simulation of the fan-shaped metal-dielectric support rod helix traveling wave tube(TWT) is carried out. On the basis of simple uniform pitch design, the helix pitch step and magnetic field step are used to improve the output power and electronic efficiency of the TWT in the working frequency band, and the problem of electron beam defocusing is solved. The final design results show that, when the working voltage is 9 kV and the working current is 210 mA, the gain of the traveling wave tube in the whole frequency band of 24-40 GHz is between 37.7 dB and 48.7 dB, the electronic efficiency is between 15.18% and 19.42%, and the output power is greater than 286 W. Comparing with the results of the original design, the growth rate increases by more than 4.19% on the electron efficiency, the growth rate of output power is more than 4.3%, especially in the range of 26-37 GHz, the growth rate of electron efficiency increases by more than 11.8%, and the growth rate of output power goes up to 11.9%. The design results are helpful to design improved fan-shaped metal-dielectric support rod for high efficiency broadband millimeter wave helix TWT.
The interaction simulation of the fan-shaped metal-dielectric support rod helix traveling wave tube(TWT) is carried out. On the basis of simple uniform pitch design, the helix pitch step and magnetic field step are used to improve the output power and electronic efficiency of the TWT in the working frequency band, and the problem of electron beam defocusing is solved. The final design results show that, when the working voltage is 9 kV and the working current is 210 mA, the gain of the traveling wave tube in the whole frequency band of 24-40 GHz is between 37.7 dB and 48.7 dB, the electronic efficiency is between 15.18% and 19.42%, and the output power is greater than 286 W. Comparing with the results of the original design, the growth rate increases by more than 4.19% on the electron efficiency, the growth rate of output power is more than 4.3%, especially in the range of 26-37 GHz, the growth rate of electron efficiency increases by more than 11.8%, and the growth rate of output power goes up to 11.9%. The design results are helpful to design improved fan-shaped metal-dielectric support rod for high efficiency broadband millimeter wave helix TWT.
2018,
30: 083003.
doi: 10.11884/HPLPB201830.170446
Abstract:
The beam control system is the nerve center of the high power phased array antenna, responsible for precise control and condition monitoring of all the cell phases in the antenna array. In order to solve the need of online updating or maintenance of control system, a remote updating system based on SoPC is constructed. A reconfigurable method of remote online updating for FPGA hardware configuration file and Nios II software program file is proposed. The boot sequence copying hardware configuration code and software code is analyzed, and the advanced BootLoader is carried out to specify boot address of the application mode image manually. The EPCS device stores a factory pattern image for remote updates and multiple application pattern images for antenna phase control. The CAN communication bus and custom CAN application layer protocols are used to transmit data and verify data, ensuring the reliability and efficiency of the transmission. The experiment verifies the feasibility of the scheme and the system can switch between multiple configuration programs. Even if the remote update fails, the FPGA can automatically load the factory mode image to ensure the system is safe and reliable. The system is simple, and the method is flexible.
The beam control system is the nerve center of the high power phased array antenna, responsible for precise control and condition monitoring of all the cell phases in the antenna array. In order to solve the need of online updating or maintenance of control system, a remote updating system based on SoPC is constructed. A reconfigurable method of remote online updating for FPGA hardware configuration file and Nios II software program file is proposed. The boot sequence copying hardware configuration code and software code is analyzed, and the advanced BootLoader is carried out to specify boot address of the application mode image manually. The EPCS device stores a factory pattern image for remote updates and multiple application pattern images for antenna phase control. The CAN communication bus and custom CAN application layer protocols are used to transmit data and verify data, ensuring the reliability and efficiency of the transmission. The experiment verifies the feasibility of the scheme and the system can switch between multiple configuration programs. Even if the remote update fails, the FPGA can automatically load the factory mode image to ensure the system is safe and reliable. The system is simple, and the method is flexible.
2018,
30: 083004.
doi: 10.11884/HPLPB201830.180025
Abstract:
A 40 kW injection locked gyrotron is designed based on theoretical calculations and simulations. The interaction structure is formed by two cavities which operate under TE01-TE03 mode pair. The state of the beam across the pre-bunching cavity is calculated with the fixed profile theory, and the operation parameters of the gyrotron under free oscillation state is calculated with the self-consistent theory. The regulation of the oscillation frequency varying with the parameters is achieved, based on which the locking bandwidth is proposed. A PIC code is used for simulating the injection locking state, a gain of 30.5 dB and a locking bandwidth of 20 MHz are achieved under a drifting length of 7 mm. If the drifting length or the input power is increased, the locking bandwidth could be wider. The calculations and simulations show that injection locking of the 40 kW gyrotron is feasible.
A 40 kW injection locked gyrotron is designed based on theoretical calculations and simulations. The interaction structure is formed by two cavities which operate under TE01-TE03 mode pair. The state of the beam across the pre-bunching cavity is calculated with the fixed profile theory, and the operation parameters of the gyrotron under free oscillation state is calculated with the self-consistent theory. The regulation of the oscillation frequency varying with the parameters is achieved, based on which the locking bandwidth is proposed. A PIC code is used for simulating the injection locking state, a gain of 30.5 dB and a locking bandwidth of 20 MHz are achieved under a drifting length of 7 mm. If the drifting length or the input power is increased, the locking bandwidth could be wider. The calculations and simulations show that injection locking of the 40 kW gyrotron is feasible.
2018,
30: 083005.
doi: 10.11884/HPLPB201830.180074
Abstract:
This paper presents a compact, high-power mode converter using, which consists of two orthogonal circular waveguides. The mode conversion is based on the coupling relationship of TE11 mode and the TM01 mode transmitting at E-plane branch of the circular waveguide. In addition, wider bandwidth is achieved by placing a tuning screw at the short end. The results show that the conversion efficiency at 12.7 GHz is 99.6% and the bandwidth greater than 90% is ranging from 11 GHz to 14 GHz.
This paper presents a compact, high-power mode converter using, which consists of two orthogonal circular waveguides. The mode conversion is based on the coupling relationship of TE11 mode and the TM01 mode transmitting at E-plane branch of the circular waveguide. In addition, wider bandwidth is achieved by placing a tuning screw at the short end. The results show that the conversion efficiency at 12.7 GHz is 99.6% and the bandwidth greater than 90% is ranging from 11 GHz to 14 GHz.
2018,
30: 083006.
doi: 10.11884/HPLPB201830.180036
Abstract:
In order to realize the phase locking of GW-level high power microwave (HPM) driven by kW-level RF source, a relativistic klystron amplifier (RKA) with four resonant cavities is designed. However, the particle in cell (PIC) simulation shows that high order mode oscillation in the device destroys the phase locking of HPM seriously. And this high order mode excitation is closely related to the coupling between middle cavities. Combining with the structure of RKA, an equivalent circuit model is built to study the process of high order mode excitation (positive feedback process). Simulations show that positive feedback process of high order mode can be controlled by adding RF lossy material to the RKA structure. And this measure increases the threshold current of the high order mode excitation. We have got a phase-locking output microwave of 2.3 GW with an input power of 4 kW in simulation. Experiments were performed on the LTD accelerator, and the input microwave was provided by a solid-state microwave source. Under the conditions of an input microwave of 10 kW, the output power achieved 1.8 GW with a gain of 52.6 dB; and the relative phase difference between input and output RF signals was about ±10° in the locking duration of 90 ns.
In order to realize the phase locking of GW-level high power microwave (HPM) driven by kW-level RF source, a relativistic klystron amplifier (RKA) with four resonant cavities is designed. However, the particle in cell (PIC) simulation shows that high order mode oscillation in the device destroys the phase locking of HPM seriously. And this high order mode excitation is closely related to the coupling between middle cavities. Combining with the structure of RKA, an equivalent circuit model is built to study the process of high order mode excitation (positive feedback process). Simulations show that positive feedback process of high order mode can be controlled by adding RF lossy material to the RKA structure. And this measure increases the threshold current of the high order mode excitation. We have got a phase-locking output microwave of 2.3 GW with an input power of 4 kW in simulation. Experiments were performed on the LTD accelerator, and the input microwave was provided by a solid-state microwave source. Under the conditions of an input microwave of 10 kW, the output power achieved 1.8 GW with a gain of 52.6 dB; and the relative phase difference between input and output RF signals was about ±10° in the locking duration of 90 ns.
2018,
30: 083007.
doi: 10.11884/HPLPB201830.180001
Abstract:
In this paper, a novel antenna based on the radiation principle of Valentine antenna is designed to radiate high-power short pulse with a 610 kV top voltage and an FFT spectrum of 0.2-2 GHz. The coaxial-to-parallel-strip balun filled with transformer oil is deployed to feed the antenna with a 50 Ω coaxial waveguide. The dielectric strength and radiation property are optimized by the dielectric material and topology structure of the antenna. Simulation result shows that the antenna has a low reflection, ultra wideband, great gain and high dielectric strength.
In this paper, a novel antenna based on the radiation principle of Valentine antenna is designed to radiate high-power short pulse with a 610 kV top voltage and an FFT spectrum of 0.2-2 GHz. The coaxial-to-parallel-strip balun filled with transformer oil is deployed to feed the antenna with a 50 Ω coaxial waveguide. The dielectric strength and radiation property are optimized by the dielectric material and topology structure of the antenna. Simulation result shows that the antenna has a low reflection, ultra wideband, great gain and high dielectric strength.
2018,
30: 083008.
doi: 10.11884/HPLPB201830.170472
Abstract:
A two-dimensional electron-thermal model of the PNP type Darlington tube is established, and the transient behaviors of the Darlington tube in the forward-active region are simulated with the injection of high power microwaves (HPMs) and electromagnetic pulses (EMPs) from the collector. A discussion and a comparison of the damage effects and the mechanism of the device under the injection of HPMs and EMPs are performed. The results show that temperature variation has a periodic rule of "decrease-increase" and temperature elevation occurs in the positive half-period, and the cylindrical region of base-emitter junction of the second transistor (near the emitter of the Darlington tube) is susceptible to damage when HPM signals are injected. While temperature keeps rising and the rate of increase presents a tendency of "rapid-slow" until the device burns out under the injection of EMP signals, and the damage location is the same as the damage area of HPM injection. In addition, the damage mechanism during the positive half-period of HPM injection is similar to that of EPM injection. Finally, the dependence relations of damage energy and damage power of EMPs and HPMs on pulse-width are obtained in a nanosecond range. It is demonstrated that energy threshold increase slowly while power threshold decrease with the increasing of pulse-width.
A two-dimensional electron-thermal model of the PNP type Darlington tube is established, and the transient behaviors of the Darlington tube in the forward-active region are simulated with the injection of high power microwaves (HPMs) and electromagnetic pulses (EMPs) from the collector. A discussion and a comparison of the damage effects and the mechanism of the device under the injection of HPMs and EMPs are performed. The results show that temperature variation has a periodic rule of "decrease-increase" and temperature elevation occurs in the positive half-period, and the cylindrical region of base-emitter junction of the second transistor (near the emitter of the Darlington tube) is susceptible to damage when HPM signals are injected. While temperature keeps rising and the rate of increase presents a tendency of "rapid-slow" until the device burns out under the injection of EMP signals, and the damage location is the same as the damage area of HPM injection. In addition, the damage mechanism during the positive half-period of HPM injection is similar to that of EPM injection. Finally, the dependence relations of damage energy and damage power of EMPs and HPMs on pulse-width are obtained in a nanosecond range. It is demonstrated that energy threshold increase slowly while power threshold decrease with the increasing of pulse-width.
2018,
30: 083201.
doi: 10.11884/HPLPB201830.180040
Abstract:
Based on the asymptotic method for high frequency electromagnetic field coupling to single wire above the ground, an asymptotic method for multiconductor transmission line (TL) is proposed. The proposed method simplifies the solving process of the scattering/reflection parameters required and therefore becomes more efficient than the previous asymptotic method for multiconductor TL. The induced currents along multiconductor TLs with different configuration are calculated using the proposed method, and the results are in good agreements with the simulated results of NEC, a full-wave analysis software. Moreover, the influence of the separation distance between the wires of the rectangular TL and the parallel TL on the induced current is analyzed. Results show that the induced currents along these two TLs change in the rectangular TL and the parallel TL change in different way, as the separation distance between the lines increases. Especially, the induced current along the parallel TL no longer changes while the separation distance increases to more than a wavelength, and is the same as that along the single wire above the perfect conducting ground with the same structure.
Based on the asymptotic method for high frequency electromagnetic field coupling to single wire above the ground, an asymptotic method for multiconductor transmission line (TL) is proposed. The proposed method simplifies the solving process of the scattering/reflection parameters required and therefore becomes more efficient than the previous asymptotic method for multiconductor TL. The induced currents along multiconductor TLs with different configuration are calculated using the proposed method, and the results are in good agreements with the simulated results of NEC, a full-wave analysis software. Moreover, the influence of the separation distance between the wires of the rectangular TL and the parallel TL on the induced current is analyzed. Results show that the induced currents along these two TLs change in the rectangular TL and the parallel TL change in different way, as the separation distance between the lines increases. Especially, the induced current along the parallel TL no longer changes while the separation distance increases to more than a wavelength, and is the same as that along the single wire above the perfect conducting ground with the same structure.
2018,
30: 083202.
doi: 10.11884/HPLPB201830.170434
Abstract:
There is great difficulty in solving systematic electronic equipment testing assessment for reductionism. Taking the typical integrative command information system for example, the information transmission process is analyzed based on the OODA loop theory, and the essential connotation of the command information system is also derived. From the perspective of complex system, the complexity of the integrative command information system is studied. Through analyzing the complexity with the unique traits of the integrative command information system, it can be concluded that there is essential difficulty of problem decomposition by custom performance testing method in systematic electronic equipment test, and the reason is that the performance testing method conforms to reductionism. To solve this difficulty, a methodology for problem decomposition is put forward based on systematology meta-synthesis method, and it is used in command and control system test assessment. An example of constructing anti-interference indexes system is given for the integrative air defense command information system. The example has illustrated the application process of the decomposition method and demonstrated that the method is of great value in effectiveness evaluation of system of systems combat test for electronic information equipment.
There is great difficulty in solving systematic electronic equipment testing assessment for reductionism. Taking the typical integrative command information system for example, the information transmission process is analyzed based on the OODA loop theory, and the essential connotation of the command information system is also derived. From the perspective of complex system, the complexity of the integrative command information system is studied. Through analyzing the complexity with the unique traits of the integrative command information system, it can be concluded that there is essential difficulty of problem decomposition by custom performance testing method in systematic electronic equipment test, and the reason is that the performance testing method conforms to reductionism. To solve this difficulty, a methodology for problem decomposition is put forward based on systematology meta-synthesis method, and it is used in command and control system test assessment. An example of constructing anti-interference indexes system is given for the integrative air defense command information system. The example has illustrated the application process of the decomposition method and demonstrated that the method is of great value in effectiveness evaluation of system of systems combat test for electronic information equipment.
2018,
30: 083203.
doi: 10.11884/HPLPB201830.180101
Abstract:
The electromagnetic radiation produced by the resonance of the target chamber is one of the sources of electromagnetic pulse generated in the experiment of ultra-short intense laser and target interaction. Based on the finite element analysis method, we simulated the two processes of the electromagnetic pulse produced by the resonance of cavity and electromagnetic pulse propagating outward through windows. The former results show that the internal structure has a significant influence on the intensity distribution and resonance frequency of the electromagnetic field. The latter simulation results show that the electric field intensity outside the window is about 40% higher than that inside the window, and the electromagnetic pulse propagates to the target outside and then spreads and attenuates in the form of spherical wave form. The intensity attenuation rule is analyzed and the fitting function of the attenuation curve is obtained.
The electromagnetic radiation produced by the resonance of the target chamber is one of the sources of electromagnetic pulse generated in the experiment of ultra-short intense laser and target interaction. Based on the finite element analysis method, we simulated the two processes of the electromagnetic pulse produced by the resonance of cavity and electromagnetic pulse propagating outward through windows. The former results show that the internal structure has a significant influence on the intensity distribution and resonance frequency of the electromagnetic field. The latter simulation results show that the electric field intensity outside the window is about 40% higher than that inside the window, and the electromagnetic pulse propagates to the target outside and then spreads and attenuates in the form of spherical wave form. The intensity attenuation rule is analyzed and the fitting function of the attenuation curve is obtained.
2018,
30: 084101.
doi: 10.11884/HPLPB201830.180093
Abstract:
Via-holes are usually required to ground for microstrip interdigital filter.The influence of the grounding via-hole is considered when modeling the overall system in traditional design methods, which will lead to the multi-factor and multi-level problem since the number, size and position of the grounding via-holes are uncertain.The problems can be avoided by proposing grounding via-hole effect in microstrip interdigital filter design.Taking Ka-band filter as an example, the traditional odd-even mode impedance method, coupling coefficient and external quality factor method, and the modification method of considering the grounding via-holes in the design process are used to design the filter respectively.The initial design results show that the center frequency of the traditional method is shifted to the left, and other parameters are much different from the design specification.The center frequency, passband range and stop rejection of the modification method meet the requirements of the specification, and the maximum insertion loss is 3.08 dB, the minimum return loss is 10.08 dB, which is helpful to reduce the subsequent iterations.
Via-holes are usually required to ground for microstrip interdigital filter.The influence of the grounding via-hole is considered when modeling the overall system in traditional design methods, which will lead to the multi-factor and multi-level problem since the number, size and position of the grounding via-holes are uncertain.The problems can be avoided by proposing grounding via-hole effect in microstrip interdigital filter design.Taking Ka-band filter as an example, the traditional odd-even mode impedance method, coupling coefficient and external quality factor method, and the modification method of considering the grounding via-holes in the design process are used to design the filter respectively.The initial design results show that the center frequency of the traditional method is shifted to the left, and other parameters are much different from the design specification.The center frequency, passband range and stop rejection of the modification method meet the requirements of the specification, and the maximum insertion loss is 3.08 dB, the minimum return loss is 10.08 dB, which is helpful to reduce the subsequent iterations.
2018,
30: 085001.
doi: 10.11884/HPLPB201830.170320
Abstract:
Electrical explosion of wire (EEW) is the first stage of wire array Z-pinch, which has great influence on the following dynamics and the final X-ray emission.In this paper, the physical processes of two-wire Z-pinch was observed by X-ray backlighting.The sub-nanosecond, micrometer-scale X-ray source was generated with X-pinches connected in series with the Zpinch.Experimental results show that electrically exploded wires in vacuum usually develop into "core-corona"structure (highdensity core surrounded by low-density corona plasma).The corona plasma is then driven to the axis by global magnetic field to form a precursor plasma column, adding to the instabilities of the implosion stage.Therefore single wire EEW experiments were carried out to increase the energy deposition of wire core so as to suppress the formation of"core-corona"structure.Experimental results show that the performance of EEW can be improved by higher rising-rate of driving current and positive radial electric field along wire surface.In order to combine the two favorable methods, a flashover switch was inserted between wire-end and cathode.As a result, the specific energy of EEW was increased by 2 times (5.7 eV/atomvs 13 eV/atom) and 3.5 times (3.4 eV/atomvs12 eV/atom) under positive and negative driving current, exceeding the atomization enthalpy of tungsten (8.8 eV/atom) by a factor of 1.4.The laser interferograms show no high-density wire core; in other words, fully vaporized (core-free) wire explosion of bare tungsten wire was achieved.
Electrical explosion of wire (EEW) is the first stage of wire array Z-pinch, which has great influence on the following dynamics and the final X-ray emission.In this paper, the physical processes of two-wire Z-pinch was observed by X-ray backlighting.The sub-nanosecond, micrometer-scale X-ray source was generated with X-pinches connected in series with the Zpinch.Experimental results show that electrically exploded wires in vacuum usually develop into "core-corona"structure (highdensity core surrounded by low-density corona plasma).The corona plasma is then driven to the axis by global magnetic field to form a precursor plasma column, adding to the instabilities of the implosion stage.Therefore single wire EEW experiments were carried out to increase the energy deposition of wire core so as to suppress the formation of"core-corona"structure.Experimental results show that the performance of EEW can be improved by higher rising-rate of driving current and positive radial electric field along wire surface.In order to combine the two favorable methods, a flashover switch was inserted between wire-end and cathode.As a result, the specific energy of EEW was increased by 2 times (5.7 eV/atomvs 13 eV/atom) and 3.5 times (3.4 eV/atomvs12 eV/atom) under positive and negative driving current, exceeding the atomization enthalpy of tungsten (8.8 eV/atom) by a factor of 1.4.The laser interferograms show no high-density wire core; in other words, fully vaporized (core-free) wire explosion of bare tungsten wire was achieved.
2018,
30: 085002.
doi: 10.11884/HPLPB201830.170528
Abstract:
To satisfy the application requirement of a high power electromagnetic pulse radiating system to a small light offground pulsed power supply, a miniature dynamic cascaded explosively-driven magnetic flux compression generator is investigated in this paper.Firstly, the structural parameters of the generator are introduced.Then its electrical parameter, input and output current are calculated by utilizing a numerical computation model based on equivalent circuit.The output characteristics of the generator was tested by experiments, in which the seed current was supplied by an initial power source based on a battery.It is found that a current pulse with a peak value of 49 kA and rise time of 5.2μs was generated on an inductive load of 1.44μH, while the energy amplification factor was 7.8.
To satisfy the application requirement of a high power electromagnetic pulse radiating system to a small light offground pulsed power supply, a miniature dynamic cascaded explosively-driven magnetic flux compression generator is investigated in this paper.Firstly, the structural parameters of the generator are introduced.Then its electrical parameter, input and output current are calculated by utilizing a numerical computation model based on equivalent circuit.The output characteristics of the generator was tested by experiments, in which the seed current was supplied by an initial power source based on a battery.It is found that a current pulse with a peak value of 49 kA and rise time of 5.2μs was generated on an inductive load of 1.44μH, while the energy amplification factor was 7.8.
2018,
30: 085003.
doi: 10.11884/HPLPB201830.170425
Abstract:
The rod-pinch diode (RPD) is a cylindrical pinched beam diode being developed as an intense pulsed small diameter bremsstrahlung source for flash X-ray radiography.The studying significance of the physical characteristics lies in optimizing geometry structure of RPD.Using PIC program and numerical simulation, a model of the rod-pinch diode operation based on space limited current at low voltage and self-magnetically limited current at high voltage is researched.Analysis shows that the diode characteristic is determined by space charge limited current at low voltage and self-magnetically limited critical current at high voltage.The simulation result is consistent with reference.Under the special conditions (space charge limited, weakly pinched and self-magnetically limited), the ratios of ion current to electron current are studied.The coefficient for calculating the self-magnetically limited ion to electron current ratio in the self-magnetically limited condition is affected by the electron and ion transit time and free from the high voltage.
The rod-pinch diode (RPD) is a cylindrical pinched beam diode being developed as an intense pulsed small diameter bremsstrahlung source for flash X-ray radiography.The studying significance of the physical characteristics lies in optimizing geometry structure of RPD.Using PIC program and numerical simulation, a model of the rod-pinch diode operation based on space limited current at low voltage and self-magnetically limited current at high voltage is researched.Analysis shows that the diode characteristic is determined by space charge limited current at low voltage and self-magnetically limited critical current at high voltage.The simulation result is consistent with reference.Under the special conditions (space charge limited, weakly pinched and self-magnetically limited), the ratios of ion current to electron current are studied.The coefficient for calculating the self-magnetically limited ion to electron current ratio in the self-magnetically limited condition is affected by the electron and ion transit time and free from the high voltage.
2018,
30: 085004.
doi: 10.11884/HPLPB201830.170346
Abstract:
A pulse forming module combining the function of energy storage and pulse shaping is designed to meet the challenge of minimization and modularization in high-power pulsed power system.The size and weight of the module have been reduced considerably due to the further development of the branches of pulse forming network to the lowest 2, while quasi-square output waveform characteristic is reserved.The module is constructed with a dozen folded film capacitors in series in a solid filmliquid transformer oil insulation system, aiming to prompt its energy storage density and thus the compact and high-voltage design.Influence of the circuit parameters on the output waveform characteristics of the module is studied by using PSpice electrical circuit simulation, and experimental test was carried out to verify it.The module shows high withstanding voltage of 120 kV with stored energy density of 41 kJ·m-3, and could output a 180 ns quasi-squared high voltage pulse.
A pulse forming module combining the function of energy storage and pulse shaping is designed to meet the challenge of minimization and modularization in high-power pulsed power system.The size and weight of the module have been reduced considerably due to the further development of the branches of pulse forming network to the lowest 2, while quasi-square output waveform characteristic is reserved.The module is constructed with a dozen folded film capacitors in series in a solid filmliquid transformer oil insulation system, aiming to prompt its energy storage density and thus the compact and high-voltage design.Influence of the circuit parameters on the output waveform characteristics of the module is studied by using PSpice electrical circuit simulation, and experimental test was carried out to verify it.The module shows high withstanding voltage of 120 kV with stored energy density of 41 kJ·m-3, and could output a 180 ns quasi-squared high voltage pulse.
2018,
30: 085005.
doi: 10.11884/HPLPB201830.170526
Abstract:
This paper presents a time-base feedback controlled LC resonance capacity charging power supply (CCPS) for Tesla transformer.The main improvement of this new type of LC resonance CCPS is that the multiplex pulse generator used to trigger resonance charging process in traditional LC resonance CCPS is replaced by a feedback circuit specially designed to offer appropriate time-delay triggering.The feedback circuit, composed of several high voltage components, has efficient immunity to electromagnetic interference.Meanwhile, the output short-circuit protection capability of the feedback circuit is available in principle.This new LC resonance CCPS is applied in several Tesla-type ultra wideband (UWB) pulse generators such as CKP1000 and CKP5000, etc.Experimental results show that the new LC resonance CCPS can operate stably in intense radiation circumstance with a repetition rate of 1000 Hz and has quick response to failure occurred in primary circuit of Tesla transformer.
This paper presents a time-base feedback controlled LC resonance capacity charging power supply (CCPS) for Tesla transformer.The main improvement of this new type of LC resonance CCPS is that the multiplex pulse generator used to trigger resonance charging process in traditional LC resonance CCPS is replaced by a feedback circuit specially designed to offer appropriate time-delay triggering.The feedback circuit, composed of several high voltage components, has efficient immunity to electromagnetic interference.Meanwhile, the output short-circuit protection capability of the feedback circuit is available in principle.This new LC resonance CCPS is applied in several Tesla-type ultra wideband (UWB) pulse generators such as CKP1000 and CKP5000, etc.Experimental results show that the new LC resonance CCPS can operate stably in intense radiation circumstance with a repetition rate of 1000 Hz and has quick response to failure occurred in primary circuit of Tesla transformer.
2018,
30: 085101.
doi: 10.11884/HPLPB201830.170438
Abstract:
The third resonant slow extraction and RF-knockout technology was adopted for Xi'an Proton Application Facility (XIPAF), which was designed for proton single event effects research.The influence of dipole and quadrupole power ripple on extracted spill was explored theoretically and simulated via TrackAll.According to a series of simulation results, ΔI/Iset≤1.2×10-4 for the quadrupole-focusing power converter, ΔI/Iset≤2×10-3 for the quadrupole defocusing converter andΔI/Iset≤4×10-4 for the dipole converter are acceptable, whereΔI represents the variance of the ouput current caused by power ripple and Iset represents the standard value of the output current without ripple.Since the synchrotron's power converters in XIPAF satisfy the same standard in terms of power ripple, it is confirmed thatΔI/Isetshould be limited to 1×10-4 for all power converters.
The third resonant slow extraction and RF-knockout technology was adopted for Xi'an Proton Application Facility (XIPAF), which was designed for proton single event effects research.The influence of dipole and quadrupole power ripple on extracted spill was explored theoretically and simulated via TrackAll.According to a series of simulation results, ΔI/Iset≤1.2×10-4 for the quadrupole-focusing power converter, ΔI/Iset≤2×10-3 for the quadrupole defocusing converter andΔI/Iset≤4×10-4 for the dipole converter are acceptable, whereΔI represents the variance of the ouput current caused by power ripple and Iset represents the standard value of the output current without ripple.Since the synchrotron's power converters in XIPAF satisfy the same standard in terms of power ripple, it is confirmed thatΔI/Isetshould be limited to 1×10-4 for all power converters.
2018,
30: 085102.
doi: 10.11884/HPLPB201830.180066
Abstract:
Slope error and evaluation criteria of bent mirror of synchrotron radiation induced from gravity are introduced.According to the bending theory of beam, a method of gravity compensation by couple combined with multi-point forces is proposed.Taking the bent mirror of the XAFS beam-line (BL14 W) at Shanghai Synchrotron Radiation Facility (SSRF) as an example, the minimum root mean square (RMS) slope error of the bent mirror under the action of two-point, three-point and fourpoint forces combined with couples are calculated, and the result is 0.092, 0.041 and 0.022μrad, respectively.The comparison between the compensation results shows that when a couple is applied to both ends of the mirror, the corresponding compensation forces decreases, and the slope errors of the couple combined with two-point, three-point and four-point forces are 52%, 61%and68% of those without couples.Obviously, the compensation method of couples combined with multi-point forces is better than the multi-point forces compensation method.
Slope error and evaluation criteria of bent mirror of synchrotron radiation induced from gravity are introduced.According to the bending theory of beam, a method of gravity compensation by couple combined with multi-point forces is proposed.Taking the bent mirror of the XAFS beam-line (BL14 W) at Shanghai Synchrotron Radiation Facility (SSRF) as an example, the minimum root mean square (RMS) slope error of the bent mirror under the action of two-point, three-point and fourpoint forces combined with couples are calculated, and the result is 0.092, 0.041 and 0.022μrad, respectively.The comparison between the compensation results shows that when a couple is applied to both ends of the mirror, the corresponding compensation forces decreases, and the slope errors of the couple combined with two-point, three-point and four-point forces are 52%, 61%and68% of those without couples.Obviously, the compensation method of couples combined with multi-point forces is better than the multi-point forces compensation method.
2018,
30: 085103.
doi: 10.11884/HPLPB201830.170485
Abstract:
The domestic 500 MHz superconducting cavity for BEPC Ⅱ has been installed and beam tested in October 2017.The related parameters of cavity during cooling down have been monitored and analyzed, the quality factor of the cavity has been improved by high RF (radio frequency) power aging, and the radiation dose has been monitored, and the situation of cavity running with beam has been analyzed.The results show that the cavity has been working very well though it had been idle for six years, and the performance of the cavity has been improved through high RF power aging.The performance of the cavity completely meets the demands of beam running.
The domestic 500 MHz superconducting cavity for BEPC Ⅱ has been installed and beam tested in October 2017.The related parameters of cavity during cooling down have been monitored and analyzed, the quality factor of the cavity has been improved by high RF (radio frequency) power aging, and the radiation dose has been monitored, and the situation of cavity running with beam has been analyzed.The results show that the cavity has been working very well though it had been idle for six years, and the performance of the cavity has been improved through high RF power aging.The performance of the cavity completely meets the demands of beam running.
2018,
30: 085104.
doi: 10.11884/HPLPB201830.180030
Abstract:
The undulator magnetic fiducialization is an important prerequisite to ensure the undulator segments' installation precision of the FEL device.A device called"magnetic landmark"was developed to achieve high precision undulator magnetic fiducialization.The landmark consists of several permanent magnets which can generate a normal and a skew quadrupole field with high gradient in two orthogonal directions.Positions of the zero point of the two quadrupole fields' horizontal component were measured and the specific use of the landmark is given.The results show that the accuracy of the magnetic center axis of an undulator after fiducialization in the landmark coordinate system is better than ±20μm in the horizontal direction and ±2μm in the vertical direction.
The undulator magnetic fiducialization is an important prerequisite to ensure the undulator segments' installation precision of the FEL device.A device called"magnetic landmark"was developed to achieve high precision undulator magnetic fiducialization.The landmark consists of several permanent magnets which can generate a normal and a skew quadrupole field with high gradient in two orthogonal directions.Positions of the zero point of the two quadrupole fields' horizontal component were measured and the specific use of the landmark is given.The results show that the accuracy of the magnetic center axis of an undulator after fiducialization in the landmark coordinate system is better than ±20μm in the horizontal direction and ±2μm in the vertical direction.
2018,
30: 085105.
doi: 10.11884/HPLPB201830.170504
Abstract:
As the key components of rapid cycling synchrotron of China Spallation Neutron Source (CSNS/RCS) collimation system, secondary collimators are used to absorb the unconstrained halo particles which are scattered by primary collimator's scrapers, they should meet the special requirements of high stability, ultra-high vacuum, high positioning accuracy and so on.Based on the design and manufacturing experience of primary collimator, the absorber which is the key part of secondary collimators is designed by using ANSYS and FLUKA, and cooling by water pipe is adopted.Combined with the control system, transient analysis has been done to ensure the feasibility of the design.
As the key components of rapid cycling synchrotron of China Spallation Neutron Source (CSNS/RCS) collimation system, secondary collimators are used to absorb the unconstrained halo particles which are scattered by primary collimator's scrapers, they should meet the special requirements of high stability, ultra-high vacuum, high positioning accuracy and so on.Based on the design and manufacturing experience of primary collimator, the absorber which is the key part of secondary collimators is designed by using ANSYS and FLUKA, and cooling by water pipe is adopted.Combined with the control system, transient analysis has been done to ensure the feasibility of the design.
2018,
30: 085106.
doi: 10.11884/HPLPB201830.180027
Abstract:
The new parametric current transformer (NPCT) in BEPC Ⅱ has heating problem in high current collide mode.To find the causes and perform stable and precise measurement, wakefield simulation and eigenmode calculation have been carried out by CST, and the steady-state temperature distribution is calculated.The cut-off frequency of ceramic gap is obtained by equivalent reflection-impedance calculation.A practical solution is put forward according to the analysis, and ideal experimental results are obtained.The experiment basically solves the heating problem, it could be a guide for current transformer (CT) improvement and applied to CT designs in the future.
The new parametric current transformer (NPCT) in BEPC Ⅱ has heating problem in high current collide mode.To find the causes and perform stable and precise measurement, wakefield simulation and eigenmode calculation have been carried out by CST, and the steady-state temperature distribution is calculated.The cut-off frequency of ceramic gap is obtained by equivalent reflection-impedance calculation.A practical solution is put forward according to the analysis, and ideal experimental results are obtained.The experiment basically solves the heating problem, it could be a guide for current transformer (CT) improvement and applied to CT designs in the future.
2018,
30: 085107.
doi: 10.11884/HPLPB201830.170355
Abstract:
This paper describes the design of a control system for 3 W1 wiggler in the Chinese High Energy Photon SourceTest Facility (HEPS-TF).The control system includes the superconducting power supply control system and the cryogenic monitor system.It is based on the Experimental Physics and Industrial Control System (EPICS) and the hardware core of the control system is a serial port server which normalizes the port to the standard RS232/485 serial port.StreamDevice has been used to develop the EPICS driver whose protocol is based on Modbus.High level applications are developed by Qt Creator embedded with EPICS Qt framework.At present, the control system has been basically completed and tested off-line.
This paper describes the design of a control system for 3 W1 wiggler in the Chinese High Energy Photon SourceTest Facility (HEPS-TF).The control system includes the superconducting power supply control system and the cryogenic monitor system.It is based on the Experimental Physics and Industrial Control System (EPICS) and the hardware core of the control system is a serial port server which normalizes the port to the standard RS232/485 serial port.StreamDevice has been used to develop the EPICS driver whose protocol is based on Modbus.High level applications are developed by Qt Creator embedded with EPICS Qt framework.At present, the control system has been basically completed and tested off-line.
2018,
30: 086001.
doi: 10.11884/HPLPB201830.180009
Abstract:
The natural circulation capacity is an important parameter that characterizes the safety capability of a nuclear reactor.We calculated the transient characteristics under the conditions with and without emergency cooling system by RELAP5/Mod 3.4, analyzed the transient natural circulation capability of the coolant flow direction reversal process, and acquired the maximum transient transfer capability.The results show: the emergency cooling system reduced fuel and coolant temperatures significantly and improved the safety of the reactor; when the decay power was reduced to 590 kW, the auxiliary pump was turned off and the reactor could be brought into a safe state with natural circulation.
The natural circulation capacity is an important parameter that characterizes the safety capability of a nuclear reactor.We calculated the transient characteristics under the conditions with and without emergency cooling system by RELAP5/Mod 3.4, analyzed the transient natural circulation capability of the coolant flow direction reversal process, and acquired the maximum transient transfer capability.The results show: the emergency cooling system reduced fuel and coolant temperatures significantly and improved the safety of the reactor; when the decay power was reduced to 590 kW, the auxiliary pump was turned off and the reactor could be brought into a safe state with natural circulation.
2018,
30: 086002.
doi: 10.11884/HPLPB201830.180062
Abstract:
A previously under-explored difficulty in cargo inspections is how to efficiently detect drugs and explosives concealed in large dense metals.Cosmic ray muon tomography is a promising non-destructive imaging technique to solve the problem because muons are naturally generated in the atmosphere and have sufficient energy to completely penetrate large dense containers.In this work it is investigated that to what extent drugs and explosives of a certain size could be discriminated from air background and metals by muon tomography within acceptable measuring time.A Geant4 Monte Carlo simulation is built based on the Tsinghua University MUon Tomography facility (TUMUTY) and a support vector machine (SVM) classifier based on machine learning is trained to differentiate drugs and explosives from air background and metals automatically.For various 20 cm×20 cm×20 cm objects, with 10 min to 30 min measuring time, drugs and explosives could be discriminated from background and metals by muon tomography with an error rate of about 1%.With 1 min, the error rate deteriorates to 12.9%.
A previously under-explored difficulty in cargo inspections is how to efficiently detect drugs and explosives concealed in large dense metals.Cosmic ray muon tomography is a promising non-destructive imaging technique to solve the problem because muons are naturally generated in the atmosphere and have sufficient energy to completely penetrate large dense containers.In this work it is investigated that to what extent drugs and explosives of a certain size could be discriminated from air background and metals by muon tomography within acceptable measuring time.A Geant4 Monte Carlo simulation is built based on the Tsinghua University MUon Tomography facility (TUMUTY) and a support vector machine (SVM) classifier based on machine learning is trained to differentiate drugs and explosives from air background and metals automatically.For various 20 cm×20 cm×20 cm objects, with 10 min to 30 min measuring time, drugs and explosives could be discriminated from background and metals by muon tomography with an error rate of about 1%.With 1 min, the error rate deteriorates to 12.9%.
2018,
30: 080000.
