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RSS2017 Vol. 29, No. 02
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2017,
29: 020101.
doi: 10.11884/HPLPB201729.160510
Abstract:
Development of a 20 GW compact repetitive Marx generator using voltage pulse trigger is summarized in this paper. Some new methods and structure models are firstly put forward in this device. Key techniques such as rectangular pulse forming, high voltage, repetition rate, long time stable operation are realized. The technical problems about repetitive and stable operation of high energy Marx generator are solved. The output power of the compact repetitive pulsed driver is aimed to exceed 20 GW, the pulse width is about 180 ns, the repetition rate is set from 1 Hz to 50 Hz. In addition, the output power and the repetition rate can be set in certain ranges. The volume of this generator is only 2.5 m3 and the weight is 2.2 t. The energy density of a pulse forming network model is 23 kJm-3. As an electron beam source, the output power of this generator is about 20 GW with singe pulse operation. The pulsed driver generator can operate stably at the output power of 16 GW, repetition rate of 30 Hz, the operating time of 10 s and the jitter of 6 ns.
Development of a 20 GW compact repetitive Marx generator using voltage pulse trigger is summarized in this paper. Some new methods and structure models are firstly put forward in this device. Key techniques such as rectangular pulse forming, high voltage, repetition rate, long time stable operation are realized. The technical problems about repetitive and stable operation of high energy Marx generator are solved. The output power of the compact repetitive pulsed driver is aimed to exceed 20 GW, the pulse width is about 180 ns, the repetition rate is set from 1 Hz to 50 Hz. In addition, the output power and the repetition rate can be set in certain ranges. The volume of this generator is only 2.5 m3 and the weight is 2.2 t. The energy density of a pulse forming network model is 23 kJm-3. As an electron beam source, the output power of this generator is about 20 GW with singe pulse operation. The pulsed driver generator can operate stably at the output power of 16 GW, repetition rate of 30 Hz, the operating time of 10 s and the jitter of 6 ns.
2017,
29: 020201.
doi: 10.11884/HPLPB201729.160460
Abstract:
New acceleration characteristics of the circular accelerators employing pulse induction modules instead of radio frequency cavities are introduced. Combining the advantages of radio-frequency circular accelerator and linear induction accelerator, a new acceleration concept has been proposed by the Japans high energy accelerator research organization (KEK), and many researches and experiments have been carried out in recent years. This paper describes the details of such works, discusses the advantages and disadvantages of the pulse induction module when it is used in a circular accelerator, and advances some improvement proposals to the pulse induction modules, arming at solving the beam loss problems in the induction synchrotron experiments.
New acceleration characteristics of the circular accelerators employing pulse induction modules instead of radio frequency cavities are introduced. Combining the advantages of radio-frequency circular accelerator and linear induction accelerator, a new acceleration concept has been proposed by the Japans high energy accelerator research organization (KEK), and many researches and experiments have been carried out in recent years. This paper describes the details of such works, discusses the advantages and disadvantages of the pulse induction module when it is used in a circular accelerator, and advances some improvement proposals to the pulse induction modules, arming at solving the beam loss problems in the induction synchrotron experiments.
2017,
29: 021002.
doi: 10.11884/HPLPB201729.160410
Abstract:
PN1Bexperimental satellite is an initiative project of China aiming at thermosphere density detection, which has been successfully launched into outer space from Taiyuan Satellite Launch Center in September, 2015. In order to satisfy the inspection standard and high precision measurement application requirements for the satellite GPS orbit determination data, and according to fact that the satellite could not provide the required installation area for the array structure of laser reflectors, PN1B satellite is equipped with multiple small (10 mm) cube prisms for satellite laser ranging. After sending the satellite into orbit, the TROS1000 mobile satellite laser ranging system was used for the tracking and laser ranging experiments. The measurement results show that the laser echo data are enough, the average number of photons per second laser echo is as high as 173, marking such small laser reflectors as the cube prisms will play an important role in the application of precise orbit determination.
PN1Bexperimental satellite is an initiative project of China aiming at thermosphere density detection, which has been successfully launched into outer space from Taiyuan Satellite Launch Center in September, 2015. In order to satisfy the inspection standard and high precision measurement application requirements for the satellite GPS orbit determination data, and according to fact that the satellite could not provide the required installation area for the array structure of laser reflectors, PN1B satellite is equipped with multiple small (10 mm) cube prisms for satellite laser ranging. After sending the satellite into orbit, the TROS1000 mobile satellite laser ranging system was used for the tracking and laser ranging experiments. The measurement results show that the laser echo data are enough, the average number of photons per second laser echo is as high as 173, marking such small laser reflectors as the cube prisms will play an important role in the application of precise orbit determination.
2017,
29: 021003.
doi: 10.11884/HPLPB201729.160432
Abstract:
In view of the problem that only using local or global intensity information cannot quickly and accurately segment images with intensity inhomogeneity, an adaptive level set model based on local and global intensity information is proposed for image segmentation. Firstly, by using local and global intensity information of image to establish the local and global energy term, and using intensity difference between the inner and the outer contour of the small neighborhood to establish weighting function, we realize adaptive adjustment of the weight between the local and global energy term, and greatly improve the efficiency and accuracy of the segmentation result. Secondly, we propose a novel energy penalty term, which avoids the re-initialization of the level set function and enhances the stability of the numerical calculation. Finally, in order to verify the superiority of the proposed model, we compare the proposed model with CV model, LBF model and LGIF model and make an objective and quantitative analysis by using the time of segmentation, the number of iterations and the similarity value. The final results show that the proposed model not only has high robustness to the initial contours, but also has high segmentation accuracy and segmentation efficiency for the images with intensity inhomogeneity.
In view of the problem that only using local or global intensity information cannot quickly and accurately segment images with intensity inhomogeneity, an adaptive level set model based on local and global intensity information is proposed for image segmentation. Firstly, by using local and global intensity information of image to establish the local and global energy term, and using intensity difference between the inner and the outer contour of the small neighborhood to establish weighting function, we realize adaptive adjustment of the weight between the local and global energy term, and greatly improve the efficiency and accuracy of the segmentation result. Secondly, we propose a novel energy penalty term, which avoids the re-initialization of the level set function and enhances the stability of the numerical calculation. Finally, in order to verify the superiority of the proposed model, we compare the proposed model with CV model, LBF model and LGIF model and make an objective and quantitative analysis by using the time of segmentation, the number of iterations and the similarity value. The final results show that the proposed model not only has high robustness to the initial contours, but also has high segmentation accuracy and segmentation efficiency for the images with intensity inhomogeneity.
2017,
29: 023001.
doi: 10.11884/HPLPB201729.160458
Abstract:
A new innovative horn antenna loaded with epsilon-near-zero(ENZ) metamaterial for phase compensation and gain enhancement is studied in this paper. The dielectric coating metallic grid with hollow structure was designed and tested based on the principle of antenna aperture phase distribution minimum variance, and an equivalent circuit model of ENZ metamaterial was established for the research of electromagnetic response of the period structure. The experiment results show that the gain has improved 1.8 dB and the aperture efficiency has improved from 0.4 to 0.6, the relative bandwidth is better than 10% by using epsilon-near-zero metamaterial proposed in this paper.
A new innovative horn antenna loaded with epsilon-near-zero(ENZ) metamaterial for phase compensation and gain enhancement is studied in this paper. The dielectric coating metallic grid with hollow structure was designed and tested based on the principle of antenna aperture phase distribution minimum variance, and an equivalent circuit model of ENZ metamaterial was established for the research of electromagnetic response of the period structure. The experiment results show that the gain has improved 1.8 dB and the aperture efficiency has improved from 0.4 to 0.6, the relative bandwidth is better than 10% by using epsilon-near-zero metamaterial proposed in this paper.
2017,
29: 023002.
doi: 10.11884/HPLPB201729.160456
Abstract:
Firstly, an X-band backward-wave oscillator(BWO) with a low guiding magnetic field is designed, whose output microwave power of 1.24 GW at frequency of 9.1 GHz is achieved under the condition of 750 kV voltage and 5.5 kA current when the strength of the guiding magnetic field is 0.46 T. In order to lower the strength of the guiding magnetic field so as to actualize the permanent-magnet-packaging of the relativistic BWO (RBWO), special slow wave structure is designed to increase the quality factor Q of the device, simultaneously increase the coupling impedance between the electron beam and the slow wave structure. Then a 0.46 T permanent magnet is developed, which is 48 cm long and 116 kg in weight. At last, experiment is carried out to investigate the RBWO with the permanent magnet, a 900 MW output power at 9.08 GHz frequency is obtained when the device is operating in 20 Hz repetitive rate for 1 s, while a 940 MW output power is obtained in single pulse condition.
Firstly, an X-band backward-wave oscillator(BWO) with a low guiding magnetic field is designed, whose output microwave power of 1.24 GW at frequency of 9.1 GHz is achieved under the condition of 750 kV voltage and 5.5 kA current when the strength of the guiding magnetic field is 0.46 T. In order to lower the strength of the guiding magnetic field so as to actualize the permanent-magnet-packaging of the relativistic BWO (RBWO), special slow wave structure is designed to increase the quality factor Q of the device, simultaneously increase the coupling impedance between the electron beam and the slow wave structure. Then a 0.46 T permanent magnet is developed, which is 48 cm long and 116 kg in weight. At last, experiment is carried out to investigate the RBWO with the permanent magnet, a 900 MW output power at 9.08 GHz frequency is obtained when the device is operating in 20 Hz repetitive rate for 1 s, while a 940 MW output power is obtained in single pulse condition.
2017,
29: 023201.
doi: 10.11884/HPLPB201729.160019
Abstract:
The dielectric property of the earth soil is expressed using the TOPP equation model of dielectric constant of soil-water mixture, the earth soil surface is simulated with model of band-limited fractal rough surface and Monte Carlo Method. The composite electromagnetic scattering from the earth soil surface based on band-limited fractal and the column with rectangular cross-section buried partially is studied using Method of Moment. The angle distribution curves of composite bistatic scattering coefficient is obtained. The composite bistatic scattering coefficient varying with the fractal dimension, the space fundamental frequency and the root mean square of the earth soil surface, the moisture capacity of earth soil, the geometric parameter, buried depth and tilt angle of the column with rectangular cross-section, and incident frequency of electromagnetic wave are calculated in detail. The results show that the influences of the fractal dimension of soil surface and other parameters on the composite scattering coefficient are very complex, and the angular distribution curves near the mirror have obvious fractal characteristics.
The dielectric property of the earth soil is expressed using the TOPP equation model of dielectric constant of soil-water mixture, the earth soil surface is simulated with model of band-limited fractal rough surface and Monte Carlo Method. The composite electromagnetic scattering from the earth soil surface based on band-limited fractal and the column with rectangular cross-section buried partially is studied using Method of Moment. The angle distribution curves of composite bistatic scattering coefficient is obtained. The composite bistatic scattering coefficient varying with the fractal dimension, the space fundamental frequency and the root mean square of the earth soil surface, the moisture capacity of earth soil, the geometric parameter, buried depth and tilt angle of the column with rectangular cross-section, and incident frequency of electromagnetic wave are calculated in detail. The results show that the influences of the fractal dimension of soil surface and other parameters on the composite scattering coefficient are very complex, and the angular distribution curves near the mirror have obvious fractal characteristics.
2017,
29: 023202.
doi: 10.11884/HPLPB201729.160476
Abstract:
An ultra-wideband resistor-loaded half-ellipse antenna with a shallow cavity for the vehicle-mounted Ground Penetrating Radar(GPR) is designed. The antenna with a pair of half-elliptical-shaped arms which is loaded by continuous resistive elements can effectively improve the input impedance characteristics and expand the bandwidth. The vehicle-mounted GPR for the exploration of lunar subsurface is taken as the background. The performance of the proposed antenna with different height above ground surface is studied, and the influence of the vehicle to the antenna is analyzed. An antenna prototype was manufactured and mounted on a vehicle and field tests were done. The simulated and measured results show that the designed antenna has a low voltage standing wave ratio, good radiation characteristics and small late-time ringing, which can satisfy the requirements of the GPR system.
An ultra-wideband resistor-loaded half-ellipse antenna with a shallow cavity for the vehicle-mounted Ground Penetrating Radar(GPR) is designed. The antenna with a pair of half-elliptical-shaped arms which is loaded by continuous resistive elements can effectively improve the input impedance characteristics and expand the bandwidth. The vehicle-mounted GPR for the exploration of lunar subsurface is taken as the background. The performance of the proposed antenna with different height above ground surface is studied, and the influence of the vehicle to the antenna is analyzed. An antenna prototype was manufactured and mounted on a vehicle and field tests were done. The simulated and measured results show that the designed antenna has a low voltage standing wave ratio, good radiation characteristics and small late-time ringing, which can satisfy the requirements of the GPR system.
2017,
29: 024101.
doi: 10.11884/HPLPB201729.160402
Abstract:
In the paper, the effects of two factors changing initial temperature and using methane and acetylene as different carbon source on synthesis of carbon nanotubes(CNTs) by gaseous detonation were studied. The CNTs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The results show that with the increase of the initial temperature, the yield of the synthesized carbon nanotubes is reduced and the degree of graphite is reduced, but the wall of the tube will be smooth and the diameter of the pipe will be increased. When using the acetylene, there are no carbon nanotubes in the synthesized products but synthesized amorphous carbon with higher graphitization degree. With increase of the amount of catalyst, product carbon coated particles increase and coating layer is clearly visible, but there are some structural defects. When the initial temperature ranges from 110 ℃ to 130 ℃, the use of methane gas is a better solution for the synthesis of CNTs with the gaseous detonation method.
In the paper, the effects of two factors changing initial temperature and using methane and acetylene as different carbon source on synthesis of carbon nanotubes(CNTs) by gaseous detonation were studied. The CNTs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The results show that with the increase of the initial temperature, the yield of the synthesized carbon nanotubes is reduced and the degree of graphite is reduced, but the wall of the tube will be smooth and the diameter of the pipe will be increased. When using the acetylene, there are no carbon nanotubes in the synthesized products but synthesized amorphous carbon with higher graphitization degree. With increase of the amount of catalyst, product carbon coated particles increase and coating layer is clearly visible, but there are some structural defects. When the initial temperature ranges from 110 ℃ to 130 ℃, the use of methane gas is a better solution for the synthesis of CNTs with the gaseous detonation method.
Novel configuration linear transformer driver with multistages in series sharing common cavity shell
2017,
29: 025001.
doi: 10.11884/HPLPB201729.160507
Abstract:
Fast Linear Transformer Drivers (FLTD) can directly produce high-power pulse with peak voltage up to tens of megavolt, peak current up to tens of mega ampere, and rise time 70-200 ns, which are widely used in Z-pinch ICF (Inertial Confinement Fusion)/ IFE (Inertial Fusion Energy), X ray radiography, high power laser and high power microwave, and so on. With the development of high power FLTD drivers for Z-pinch ICF/IFE, it is resolved immediately that hundreds of thousands of high power gas switches should be triggered with accurate sequences. A creative topologic FLTD structure with multistages in series sharing induction cavity shell is presented and a novel trigger method achieving nearly ideal IVA triggering sequence is put forward, by which only one trigger pulse is imported to the novel FLTD cavity shell based on an unclosed cores brick and azimutal line in cavities realizing the gas switches triggering in synchronization. The circuit model and three-dimension electromagnetic model of the new structure of three-stage series FLTD sharing induction cavity shell are developed. The simulating results of the equivalent circuits and electromagnetic models demonstrate that the novel configuration FLTDs have the same output parameters and performances as the traditional FLTDs, and validate the possibility and practicability of the novel configuration FLTDs. Based on the novel configuration FLTD and the triggering method, it is hopeful to resolve the huge challenges and difficulties that high power FLTD drivers for Z-pinch ICF/IFE would have too much import triggering and charging cables and the serious requirements for acute triggering sequences of large-scale gas switches.
Fast Linear Transformer Drivers (FLTD) can directly produce high-power pulse with peak voltage up to tens of megavolt, peak current up to tens of mega ampere, and rise time 70-200 ns, which are widely used in Z-pinch ICF (Inertial Confinement Fusion)/ IFE (Inertial Fusion Energy), X ray radiography, high power laser and high power microwave, and so on. With the development of high power FLTD drivers for Z-pinch ICF/IFE, it is resolved immediately that hundreds of thousands of high power gas switches should be triggered with accurate sequences. A creative topologic FLTD structure with multistages in series sharing induction cavity shell is presented and a novel trigger method achieving nearly ideal IVA triggering sequence is put forward, by which only one trigger pulse is imported to the novel FLTD cavity shell based on an unclosed cores brick and azimutal line in cavities realizing the gas switches triggering in synchronization. The circuit model and three-dimension electromagnetic model of the new structure of three-stage series FLTD sharing induction cavity shell are developed. The simulating results of the equivalent circuits and electromagnetic models demonstrate that the novel configuration FLTDs have the same output parameters and performances as the traditional FLTDs, and validate the possibility and practicability of the novel configuration FLTDs. Based on the novel configuration FLTD and the triggering method, it is hopeful to resolve the huge challenges and difficulties that high power FLTD drivers for Z-pinch ICF/IFE would have too much import triggering and charging cables and the serious requirements for acute triggering sequences of large-scale gas switches.
2017,
29: 025002.
doi: 10.11884/HPLPB201729.160371
Abstract:
This paper presents a compact high-voltage nanosecond pulse generator, which combines high-coupling Tesla transformer with spiral forming line (FL). The spiral FL charged from the build-in Tesla transformer includes an outer shield cylinder, a spiral middle cylinder, and an inner conductor cylinder. At both sides of the FL, inner and outer cylinders are all short-circuit connected. One end of the spiral middle cylinder is open-circuit connected, the other end passes through short-circuit interface of inner and outer cylinders, and is connected to one electrode of the main switch. Such structure is simple and compact, which can generate high-quality pulse waveform with fast front and flat top. One design example of FL with Midel 7131 synthetic ester dielectric is given in the end of this paper, and the calculative and simulative results indicate that a pulse with 10 GW peak power and 100 ns width can be generated by the 2 m long FL with 0.88 m interior diameter of outer cylinder.
This paper presents a compact high-voltage nanosecond pulse generator, which combines high-coupling Tesla transformer with spiral forming line (FL). The spiral FL charged from the build-in Tesla transformer includes an outer shield cylinder, a spiral middle cylinder, and an inner conductor cylinder. At both sides of the FL, inner and outer cylinders are all short-circuit connected. One end of the spiral middle cylinder is open-circuit connected, the other end passes through short-circuit interface of inner and outer cylinders, and is connected to one electrode of the main switch. Such structure is simple and compact, which can generate high-quality pulse waveform with fast front and flat top. One design example of FL with Midel 7131 synthetic ester dielectric is given in the end of this paper, and the calculative and simulative results indicate that a pulse with 10 GW peak power and 100 ns width can be generated by the 2 m long FL with 0.88 m interior diameter of outer cylinder.
2017,
29: 025003.
doi: 10.11884/HPLPB201729.160450
Abstract:
In this paper, firstly, the fault current of DC line disconnector is analyzed based on international thermonuclear experimental reactor (ITER) poloidal field(PF) converter system to propose the short-circuit test requirement of ITER DC line disconnector. Then, the short-circuit test scheme is designed based on the DC test platform in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), including the selection of transformer tap position, the calculation of the DC voltage corresponding to the test current and so on. Finally, the feasibility of the test scheme is verified by simulation and experiment, and it is proved by the test results that the fault suppression ability of DC line disconnector meets the requirement of ITER converter operation. By analysis and calculation, 350 kA test current needs the DC voltage 270 V. In the test, if the DC voltage is preset to 270 V, the test current is less than 350 kA. After the DC voltage is preset to 300 V, the peak of test current can reach 362.5 kA and the duration of more than 350 kA can be up to 100 ms. The difference between the actual preset DC voltage and its theoretically calculated value is 30 V, which is caused by the voltage fluctuation of the power grid.
In this paper, firstly, the fault current of DC line disconnector is analyzed based on international thermonuclear experimental reactor (ITER) poloidal field(PF) converter system to propose the short-circuit test requirement of ITER DC line disconnector. Then, the short-circuit test scheme is designed based on the DC test platform in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), including the selection of transformer tap position, the calculation of the DC voltage corresponding to the test current and so on. Finally, the feasibility of the test scheme is verified by simulation and experiment, and it is proved by the test results that the fault suppression ability of DC line disconnector meets the requirement of ITER converter operation. By analysis and calculation, 350 kA test current needs the DC voltage 270 V. In the test, if the DC voltage is preset to 270 V, the test current is less than 350 kA. After the DC voltage is preset to 300 V, the peak of test current can reach 362.5 kA and the duration of more than 350 kA can be up to 100 ms. The difference between the actual preset DC voltage and its theoretically calculated value is 30 V, which is caused by the voltage fluctuation of the power grid.
2017,
29: 025004.
doi: 10.11884/HPLPB201729.160451
Abstract:
Based on the simplified model of electrically exploded opening switch(EEOS) and the zero-dimension model of solid liner, the code D-liner, which was designed to simulate implosion of solid liner driven by disk explosive magnetic generator(DEMG) with EEOS, was compiled with Matlab. To optimize the parameters of solid liner and analyze the variation of parameters, such as the voltage of EEOS, radius and velocity of liner and the effect of EEOS on DEMG current, the system with DEMG, EEOS and solid liner was simulated. The simulation results show that when the initial current is 5.9 MA, the 400 mm ten-element DEMG with EEOS, whose length is 72 cm and thickness is 120 m, can output 31 MA current on 50 g cylindrical aluminum liner with a characteristic rise time of 1.6 s, that the EEOS can transfer high voltage (230 kV) to the liner and that the 50 g cylindrical aluminum liner can be driven to 13.7 km/s.
Based on the simplified model of electrically exploded opening switch(EEOS) and the zero-dimension model of solid liner, the code D-liner, which was designed to simulate implosion of solid liner driven by disk explosive magnetic generator(DEMG) with EEOS, was compiled with Matlab. To optimize the parameters of solid liner and analyze the variation of parameters, such as the voltage of EEOS, radius and velocity of liner and the effect of EEOS on DEMG current, the system with DEMG, EEOS and solid liner was simulated. The simulation results show that when the initial current is 5.9 MA, the 400 mm ten-element DEMG with EEOS, whose length is 72 cm and thickness is 120 m, can output 31 MA current on 50 g cylindrical aluminum liner with a characteristic rise time of 1.6 s, that the EEOS can transfer high voltage (230 kV) to the liner and that the 50 g cylindrical aluminum liner can be driven to 13.7 km/s.
2017,
29: 025005.
doi: 10.11884/HPLPB201729.160473
Abstract:
A compact seed source for explosive magnetic flux compression generators was developed, and its components, working principle, best output time sequence model were analyzed. An explosive-driven slide unit was designed for switching scheme, and its performance was tested at high voltage. The compact seed source is a system with Ф132 mm200 mm volume, 12.5 kg weight, 5 kV operating voltage, nearly 750 J storing energy, less than 30 s charging time, capable of delivering energy more than 600 J or current more than 5.4 kA into an flux compression generators load (42 H, 78 m) at static condition, coupling energy more than 550 J or current more than 5.2 kA at dynamic condition, time sequence control error less than 5 s, effect energy density more than 200 mJ/cm3, and transfer efficiency more than 75%.
A compact seed source for explosive magnetic flux compression generators was developed, and its components, working principle, best output time sequence model were analyzed. An explosive-driven slide unit was designed for switching scheme, and its performance was tested at high voltage. The compact seed source is a system with Ф132 mm200 mm volume, 12.5 kg weight, 5 kV operating voltage, nearly 750 J storing energy, less than 30 s charging time, capable of delivering energy more than 600 J or current more than 5.4 kA into an flux compression generators load (42 H, 78 m) at static condition, coupling energy more than 550 J or current more than 5.2 kA at dynamic condition, time sequence control error less than 5 s, effect energy density more than 200 mJ/cm3, and transfer efficiency more than 75%.
2017,
29: 025006.
doi: 10.11884/HPLPB201729.160487
Abstract:
When a strong magnetic field (above megagauss) diffuses into a solid metal, the magnetic field will diffuse into the metal in the form of a sharp-front wave. The phenomenon of sharp-front magnetic diffusion wave is studied using 1D MHD simulation for cylindrical implosion magnetic flux compression experiment, in which the liner is stainless steel304. Results indicate that sharp-front magnetic diffusion wave will happen when the magnetic field in cavity is compressed above 350 T. The magnetic diffusion wavefront advances rapidly from the inner of the liner to the outer, causing partial leakage of the magnetic field. It is adverse to the magnetic flux compression process. At the same time, as the inner of the liner is rapidly heated to the ionization temperature, a plasma layer will be formed near the inner, which greatly slows down the velocity of the magnetic field diffusing from the cavity to the liner. In the process of magnetic flux compression, sharp-front magnetic diffusion wave and the plasma layer have opposite effects to magnetic diffusion. They compete with each other in the development, and play the dominant role in different stage respectively.
When a strong magnetic field (above megagauss) diffuses into a solid metal, the magnetic field will diffuse into the metal in the form of a sharp-front wave. The phenomenon of sharp-front magnetic diffusion wave is studied using 1D MHD simulation for cylindrical implosion magnetic flux compression experiment, in which the liner is stainless steel304. Results indicate that sharp-front magnetic diffusion wave will happen when the magnetic field in cavity is compressed above 350 T. The magnetic diffusion wavefront advances rapidly from the inner of the liner to the outer, causing partial leakage of the magnetic field. It is adverse to the magnetic flux compression process. At the same time, as the inner of the liner is rapidly heated to the ionization temperature, a plasma layer will be formed near the inner, which greatly slows down the velocity of the magnetic field diffusing from the cavity to the liner. In the process of magnetic flux compression, sharp-front magnetic diffusion wave and the plasma layer have opposite effects to magnetic diffusion. They compete with each other in the development, and play the dominant role in different stage respectively.
2017,
29: 025007.
doi: 10.11884/HPLPB201729.160496
Abstract:
A multi-gap gas switch was designed for the LTD stage to replace the switch which has a high self-breakdown probability at the voltage over 80 kV. The shape of the electrode was designed to be circularity due to the electric field simulation of the electrode. The total length of the switchs gaps was increased from 28 mm to 36 mm while the number of the gaps increased from 4 to 6. The distortion ratio of electric field was 3.98 when the switch was charged to 100 kV and triggered by 100 kV. The self-breakdown voltage testing has been conducted and the relation between self-breakdown voltage and gas pressure was obtained when the switch was filled with dry-air. As the pressure changed from 0.10 MPa to 0.20 MPa, the self-breakdown voltage increased from 103 kV to 194 kV. The experimental results of triggering feature show that the new switch had 40.1 ns delay with 1.3 ns jitter operating at 90 kV which was 60% of the self-breakdown voltage.
A multi-gap gas switch was designed for the LTD stage to replace the switch which has a high self-breakdown probability at the voltage over 80 kV. The shape of the electrode was designed to be circularity due to the electric field simulation of the electrode. The total length of the switchs gaps was increased from 28 mm to 36 mm while the number of the gaps increased from 4 to 6. The distortion ratio of electric field was 3.98 when the switch was charged to 100 kV and triggered by 100 kV. The self-breakdown voltage testing has been conducted and the relation between self-breakdown voltage and gas pressure was obtained when the switch was filled with dry-air. As the pressure changed from 0.10 MPa to 0.20 MPa, the self-breakdown voltage increased from 103 kV to 194 kV. The experimental results of triggering feature show that the new switch had 40.1 ns delay with 1.3 ns jitter operating at 90 kV which was 60% of the self-breakdown voltage.
2017,
29: 025008.
doi: 10.11884/HPLPB201729.160136
Abstract:
Using the calculation program for the semiconductor devices system-generated electromagnetic pulse(SGEMP) and dose rate combined effect, we analysed the combined effect of the cables BJT load when the cable was radiated by X-ray. This paper presents, the feature and the law of the combined effect of SGEMP and dose rate. Under the combined effect, the reverse breakdown voltage reduced as the quantities of carrier in the BJT increased rapidly. The damage of BJT occurs more easily under the combined effect than under the SGEMP effect or the dose rate effect. The calculation program for the SGEMP and dose rate effect could be used for analysing the effect mechanism and law of other semiconductor devices.
Using the calculation program for the semiconductor devices system-generated electromagnetic pulse(SGEMP) and dose rate combined effect, we analysed the combined effect of the cables BJT load when the cable was radiated by X-ray. This paper presents, the feature and the law of the combined effect of SGEMP and dose rate. Under the combined effect, the reverse breakdown voltage reduced as the quantities of carrier in the BJT increased rapidly. The damage of BJT occurs more easily under the combined effect than under the SGEMP effect or the dose rate effect. The calculation program for the SGEMP and dose rate effect could be used for analysing the effect mechanism and law of other semiconductor devices.
2017,
29: 025009.
doi: 10.11884/HPLPB201729.160453
Abstract:
The paper presents a design of high voltage square-wave pulse generator based on 16 graded Marx topology with IGBT solid-state semiconductor switch devices. A composed switch module consisted of 9 serial IGBTs is adopted as the discharge switch of Marx unit. The open and close of all the IGBT switches are triggered by the inducted signal from pulse transformer. The output pulse amplitude is adjustable from several kilovolts to 200 kV. In addition, the width of output pulse is adjustable from 1.5 s to 10 s, varying with the width of the external trigger signal. The rising-edge of pulse is below 500 ns, the falling-edge is below 2.3 s. The flattop decline of the pulse is less than 2% when output voltage is greater than 100 kV and output current is approximately 20 A.
The paper presents a design of high voltage square-wave pulse generator based on 16 graded Marx topology with IGBT solid-state semiconductor switch devices. A composed switch module consisted of 9 serial IGBTs is adopted as the discharge switch of Marx unit. The open and close of all the IGBT switches are triggered by the inducted signal from pulse transformer. The output pulse amplitude is adjustable from several kilovolts to 200 kV. In addition, the width of output pulse is adjustable from 1.5 s to 10 s, varying with the width of the external trigger signal. The rising-edge of pulse is below 500 ns, the falling-edge is below 2.3 s. The flattop decline of the pulse is less than 2% when output voltage is greater than 100 kV and output current is approximately 20 A.
2017,
29: 026001.
doi: 10.11884/HPLPB201729.160436
Abstract:
This paper describes architecture and characteristics of experimental physics and industrial control system(EPICS), and the structure and characteristics of the monitoring network of the poloidal field power supply control system based on EPICS. It focuses on the development and application of EPICS device support in monitoring network of poloidal field power supply control system. The EPICS designed in this paper monitors the status, sends the command of opening or closing the switches, sets the configuration parameters, and controls the time-sequence for the local controllers in the poloidal field power supply control system. When a breakdown occurs, it can give an alarm and the software can locate the system fault. This system can monitor nearly 2 thousands digital and analog signals and support multi-user operating. The good features of EPICS are very helpful for the integration of the poloidal field power supply control system.
This paper describes architecture and characteristics of experimental physics and industrial control system(EPICS), and the structure and characteristics of the monitoring network of the poloidal field power supply control system based on EPICS. It focuses on the development and application of EPICS device support in monitoring network of poloidal field power supply control system. The EPICS designed in this paper monitors the status, sends the command of opening or closing the switches, sets the configuration parameters, and controls the time-sequence for the local controllers in the poloidal field power supply control system. When a breakdown occurs, it can give an alarm and the software can locate the system fault. This system can monitor nearly 2 thousands digital and analog signals and support multi-user operating. The good features of EPICS are very helpful for the integration of the poloidal field power supply control system.
2017,
29: 026002.
doi: 10.11884/HPLPB201729.160245
Abstract:
The design basis source terms provide a basis for safety analysis of nuclear power plant and the foundation of the radiation shielding calculation. In this paper, based on the research of reactor core, primary loop, secondary loop and airborne radioactive source term of pressurized water reactor, migration constants and nuclear reaction constants are introduced by analogy to decay constants, then an integrated calculation method is proposed for calculating the above source terms. The aforesaid equations are solved by program based on the TTA algorithm where the discrete time approximations are applied to, taking account of the source equation characteristics of variable, coefficient, large, sparse and stiff. The results comparing with the typical pressurized water reactor engineering documents are also given in this paper, which verify the correctness and necessity of the program.
The design basis source terms provide a basis for safety analysis of nuclear power plant and the foundation of the radiation shielding calculation. In this paper, based on the research of reactor core, primary loop, secondary loop and airborne radioactive source term of pressurized water reactor, migration constants and nuclear reaction constants are introduced by analogy to decay constants, then an integrated calculation method is proposed for calculating the above source terms. The aforesaid equations are solved by program based on the TTA algorithm where the discrete time approximations are applied to, taking account of the source equation characteristics of variable, coefficient, large, sparse and stiff. The results comparing with the typical pressurized water reactor engineering documents are also given in this paper, which verify the correctness and necessity of the program.
2017,
29: 026003.
doi: 10.11884/HPLPB201729.160252
Abstract:
The core power capability verifications is an important part of the core design safety verifications. The method used in currently published papers is a synthesis method combining 1D and 2D computations, which is very conservative. Three-dimensional method for core power capability verification is still conservative as it can not tell how much margin there is. This paper introduces the methodology of the power capability verifications of the plants designed in CPR1000. The conservative of the methodology was demonstrated from the input assumptions and the calculation process, from this paper. It is suggested that the uncertainty should be reconsidered with a factor of 1.04 being removed for the input data. The operation domain should be decreased, and cases that would never occur could be deleted in the calculation. When the deviation value from nucleate boiling ratio exceeds the limit, the limits of operating domain and the uncertainty of hot channel factor for specific enthalpy rise could be reanalyzed to meet the safety requirements.
The core power capability verifications is an important part of the core design safety verifications. The method used in currently published papers is a synthesis method combining 1D and 2D computations, which is very conservative. Three-dimensional method for core power capability verification is still conservative as it can not tell how much margin there is. This paper introduces the methodology of the power capability verifications of the plants designed in CPR1000. The conservative of the methodology was demonstrated from the input assumptions and the calculation process, from this paper. It is suggested that the uncertainty should be reconsidered with a factor of 1.04 being removed for the input data. The operation domain should be decreased, and cases that would never occur could be deleted in the calculation. When the deviation value from nucleate boiling ratio exceeds the limit, the limits of operating domain and the uncertainty of hot channel factor for specific enthalpy rise could be reanalyzed to meet the safety requirements.
2017,
29: 026004.
doi: 10.11884/HPLPB201729.160332
Abstract:
Evaluated nuclear data libraries are the basis of reactor physics analysis. This study investigates major versions of evaluated nuclear data libraries in various stages, namely ENDF/B-Ⅳ, Ⅴ.2, Ⅵ.8, Ⅶ.0 and Ⅶ.1, which are then processed by the internationally renowned nuclear data processing code NJOY to obtain five groups of continuous energy point cross section libraries. Micro cross sections of certain nuclides are compared and Reactor Monte Carlo Code (RMC) is used for verification of criticality benchmark. The result shows that continuous energy neutron cross section libraries, based on ENDF/B-Ⅶ.1, has higher accuracy and reliability.
Evaluated nuclear data libraries are the basis of reactor physics analysis. This study investigates major versions of evaluated nuclear data libraries in various stages, namely ENDF/B-Ⅳ, Ⅴ.2, Ⅵ.8, Ⅶ.0 and Ⅶ.1, which are then processed by the internationally renowned nuclear data processing code NJOY to obtain five groups of continuous energy point cross section libraries. Micro cross sections of certain nuclides are compared and Reactor Monte Carlo Code (RMC) is used for verification of criticality benchmark. The result shows that continuous energy neutron cross section libraries, based on ENDF/B-Ⅶ.1, has higher accuracy and reliability.
2017,
29: 029001.
doi: 10.11884/HPLPB201729.160372
Abstract:
Graphene（Gr）-CBN-Ni composite coating layer was fabricated by laser cladding through pre-set the mixture of nickel, graphene and CBN powders on AISI 4140 steel substrate. Microstructures and surface and sectional surface morphologies were studied using scanning electron microscopy (SEM), XRD and Raman spectroscopy. It is proved by X-ray diffraction (XRD) patterns and Raman spectra that graphene and CBN exist in the laser cladded coating layer. The nanomechanical properties and wear and friction properties were studied. The test results show that as the CBN content increases, the coating layer has better properties. The hardness and modulus of coating layer were significantly enhanced with the CBN content increasing. The average hardness were 4.3 GPa and 6.2 GPa, the average modulus were 101 GPa and 140 GPa, respectively. For 6% CBN content coating, the friction coefficient reduced to 0.15, while the substrates was 0.2, and the wear loss was only the half amount compared with that of substrates.
Graphene（Gr）-CBN-Ni composite coating layer was fabricated by laser cladding through pre-set the mixture of nickel, graphene and CBN powders on AISI 4140 steel substrate. Microstructures and surface and sectional surface morphologies were studied using scanning electron microscopy (SEM), XRD and Raman spectroscopy. It is proved by X-ray diffraction (XRD) patterns and Raman spectra that graphene and CBN exist in the laser cladded coating layer. The nanomechanical properties and wear and friction properties were studied. The test results show that as the CBN content increases, the coating layer has better properties. The hardness and modulus of coating layer were significantly enhanced with the CBN content increasing. The average hardness were 4.3 GPa and 6.2 GPa, the average modulus were 101 GPa and 140 GPa, respectively. For 6% CBN content coating, the friction coefficient reduced to 0.15, while the substrates was 0.2, and the wear loss was only the half amount compared with that of substrates.
2017,
29: 029002.
doi: 10.11884/HPLPB201729.160367
Abstract:
Thermal fatigue failure is easy to occur on H13 steel surface under working condition, the Co-based coating was fabricated by Nd:YAG laser on H13 steel. Microstructure, distribution of elements and composition of phases were investigated by means of optical microscope(OM), scanning electron microscope(SEM), energy dispersive spectrometer(EDS) and X-ray diffraction(XRD).The effect of thermal fatigue on microhardness of Co-based coating and quenching-tempering H13 steel was tested by microhardness tester. The results show that: From bottom to the surface of Co-based coating, planar crystal, cellular crystal, dendrite crystal and equiaxed crystal were observed; Co-based alloy coating is mainly composed of -Co and M23C6, M2O3 and M3O4(M=Fe, Co, Cr)are produced on the surface of coating after thermal cycling; Microhardness of Co-based coating which could reach 706HV0.2, decreased gradually. After 1000 thermal cycles, the microhardness decreases of Co-based alloy coating and H13 steel are 24.4% and 37.7%, respectively; The surface of the Co-based coating has no thermal cracks, while that of H13 steel has a large number of thermal cracks; Cr2O3 oxide film is formed on Co-based alloy coating, which makes thermal fatigue resistance of coating better than that of H13 steel.
Thermal fatigue failure is easy to occur on H13 steel surface under working condition, the Co-based coating was fabricated by Nd:YAG laser on H13 steel. Microstructure, distribution of elements and composition of phases were investigated by means of optical microscope(OM), scanning electron microscope(SEM), energy dispersive spectrometer(EDS) and X-ray diffraction(XRD).The effect of thermal fatigue on microhardness of Co-based coating and quenching-tempering H13 steel was tested by microhardness tester. The results show that: From bottom to the surface of Co-based coating, planar crystal, cellular crystal, dendrite crystal and equiaxed crystal were observed; Co-based alloy coating is mainly composed of -Co and M23C6, M2O3 and M3O4(M=Fe, Co, Cr)are produced on the surface of coating after thermal cycling; Microhardness of Co-based coating which could reach 706HV0.2, decreased gradually. After 1000 thermal cycles, the microhardness decreases of Co-based alloy coating and H13 steel are 24.4% and 37.7%, respectively; The surface of the Co-based coating has no thermal cracks, while that of H13 steel has a large number of thermal cracks; Cr2O3 oxide film is formed on Co-based alloy coating, which makes thermal fatigue resistance of coating better than that of H13 steel.
2017,
29: 029003.
doi: 10.11884/HPLPB201729.160431
Abstract:
Two-dimensional frequency shift laser Doppler velocimetry (LDV) is used to measure the instantaneous velocity of suspended particles in oil, according to four different situations of suspended particles going through the pinhole aperture of LDV. The original processing method of instantaneous velocity of suspended particles LDV is improved, an analysis processing method is proposed. The improved method shows better stability in measuring the instantaneous velocity of suspended particle, it can characterize the change trends of particle group with time when a group of particles are passing through the pinhole aperture in LDV, and it enhances utilization efficiency of the sampling data of the frequency shift LDV. This method further accurately characterizes the distribution and motion trajectory of two-dimensional instantaneous velocity of suspended particles in oil, providing theoretical support for the characterization of the instantaneous velocity of suspended particles in the experimental measurement of LDV.
Two-dimensional frequency shift laser Doppler velocimetry (LDV) is used to measure the instantaneous velocity of suspended particles in oil, according to four different situations of suspended particles going through the pinhole aperture of LDV. The original processing method of instantaneous velocity of suspended particles LDV is improved, an analysis processing method is proposed. The improved method shows better stability in measuring the instantaneous velocity of suspended particle, it can characterize the change trends of particle group with time when a group of particles are passing through the pinhole aperture in LDV, and it enhances utilization efficiency of the sampling data of the frequency shift LDV. This method further accurately characterizes the distribution and motion trajectory of two-dimensional instantaneous velocity of suspended particles in oil, providing theoretical support for the characterization of the instantaneous velocity of suspended particles in the experimental measurement of LDV.
2017,
29: 021001.
doi: 10.11884/HPLPB201729.160435
Abstract:
Previously, we proposed a binary trapezoidal transmission grating with the properties of quasi single-order diffraction. Numerical simulations based on the scalar diffraction theory and a visible experiment have been carried out to verify the diffraction properties in far-field. However, this work didnt give the analytic expression of the far-field intensity distribution and grating equation of the novel two-dimensional grating. Therefore, it is impossible to estimate the intensity distribution and position on the screen of every diffraction order quickly when the grating is applied to the actual spectral measurement, and at present these could only be obtained by the numerical simulation based on the theory of scalar diffraction slowly. To solve the above problem and use this novel grating in ray-tracing calculations, the analytic theory must be improved to describe the intensity distribution and grating equation of every diffraction order. In this paper, we give the analytical expression of the intensity distribution and the grating equation satisfies both transmission type and reflection type cases by using the method of analytical derivation. Finally, comparisons are made between the results of calculation by our analytical expression and simulation by the scalar diffraction module of the X-Lab to prove the validity of the analytical theory.
Previously, we proposed a binary trapezoidal transmission grating with the properties of quasi single-order diffraction. Numerical simulations based on the scalar diffraction theory and a visible experiment have been carried out to verify the diffraction properties in far-field. However, this work didnt give the analytic expression of the far-field intensity distribution and grating equation of the novel two-dimensional grating. Therefore, it is impossible to estimate the intensity distribution and position on the screen of every diffraction order quickly when the grating is applied to the actual spectral measurement, and at present these could only be obtained by the numerical simulation based on the theory of scalar diffraction slowly. To solve the above problem and use this novel grating in ray-tracing calculations, the analytic theory must be improved to describe the intensity distribution and grating equation of every diffraction order. In this paper, we give the analytical expression of the intensity distribution and the grating equation satisfies both transmission type and reflection type cases by using the method of analytical derivation. Finally, comparisons are made between the results of calculation by our analytical expression and simulation by the scalar diffraction module of the X-Lab to prove the validity of the analytical theory.
