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RSS2015 Vol. 27, No. 12
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2015,
27: 120101.
doi: 10.11884/HPLPB201527.120101
Abstract:
High power fiber end-cap is an essential component for kW-level fiber lasers, the key technique of which is the splicing of fiber end-caps with low loss and high tension strength. Due to the huge difference of the diameters of fiber and large-size end-cap, the splicing of them cannot be realized by traditional fusion splicers. A fiber end-cap splicing system is designed and built. The splicing art is implemented for different size end-caps with good tension strength. Output power with 3.01 kW is realized with a single-mode fiber end-cap while only heating up by 7 ℃/kW without active cooling. Output power with 6.08 kW is realized with a multi-mode fiber end-cap while only heating up by 6 ℃/kW without active cooling.
High power fiber end-cap is an essential component for kW-level fiber lasers, the key technique of which is the splicing of fiber end-caps with low loss and high tension strength. Due to the huge difference of the diameters of fiber and large-size end-cap, the splicing of them cannot be realized by traditional fusion splicers. A fiber end-cap splicing system is designed and built. The splicing art is implemented for different size end-caps with good tension strength. Output power with 3.01 kW is realized with a single-mode fiber end-cap while only heating up by 7 ℃/kW without active cooling. Output power with 6.08 kW is realized with a multi-mode fiber end-cap while only heating up by 6 ℃/kW without active cooling.
2015,
27: 120102.
doi: 10.11884/HPLPB201527.120102
Abstract:
Based on bound-to-continuum intersubband transition, the 2.5 THz quantum cascade laser with a continuous-wave (CW) output power of several mW is achieved. The lasing frequency of the device can be tuned by changing the applied current. The device shows a CW output power more than 6 mW, with a threshold current density of 120 A/cm2, and a lasing work temperature up to 60 K, and it is a quasi-Gaussian intensity distribution after beam reformation by using Si lens.
Based on bound-to-continuum intersubband transition, the 2.5 THz quantum cascade laser with a continuous-wave (CW) output power of several mW is achieved. The lasing frequency of the device can be tuned by changing the applied current. The device shows a CW output power more than 6 mW, with a threshold current density of 120 A/cm2, and a lasing work temperature up to 60 K, and it is a quasi-Gaussian intensity distribution after beam reformation by using Si lens.
2015,
27: 120201.
doi: 10.11884/HPLPB201527.120201
Abstract:
Field-to-line coupling model research is an important part of electromagnetic compatibility analysis and electromagnetic effects assessment. At low frequency, the classical field-to-line model based on quasi-TEM wave approximation can be used to calculate the current and voltage response excited by the external field. However, if the incident frequency becomes high enough that the corresponding wavelength is comparable to the transverse size of the transmission line, the classical model will produce unacceptable model error. Therefore it is necessary to develop high-frequency field-to line coupling model. This paper introduces the research progress of high-frequency field-to-line coupling models for multi-conductor transmission line. A detailed analysis and comparison of TRI model and TLST model (two main branches of high-frequency field-to-line coupling model) are given. Then the principle of the TLST model is briefly introduced and the models validity and accuracy are illustrated by a simulation example. Finally, the research contents and objectives of high-frequency field-to-line coupling model are summarized and prospected.
Field-to-line coupling model research is an important part of electromagnetic compatibility analysis and electromagnetic effects assessment. At low frequency, the classical field-to-line model based on quasi-TEM wave approximation can be used to calculate the current and voltage response excited by the external field. However, if the incident frequency becomes high enough that the corresponding wavelength is comparable to the transverse size of the transmission line, the classical model will produce unacceptable model error. Therefore it is necessary to develop high-frequency field-to line coupling model. This paper introduces the research progress of high-frequency field-to-line coupling models for multi-conductor transmission line. A detailed analysis and comparison of TRI model and TLST model (two main branches of high-frequency field-to-line coupling model) are given. Then the principle of the TLST model is briefly introduced and the models validity and accuracy are illustrated by a simulation example. Finally, the research contents and objectives of high-frequency field-to-line coupling model are summarized and prospected.
2015,
27: 120202.
doi: 10.11884/HPLPB201527.120202
Abstract:
In order to achieve tritium self-sustaining and energy amplification of the magnetic confinement fusion reactors, sub-critical blanket and tritium breeding blanket were set around the plasma region. We adopted natural uranium alloy as fuel, light water as coolant and moderator and embedded pressure tube sub-critical blanket as blanket design. By the analysis of neutronic physical properties, structural concept design, thermal-hydraulic performance and reactor safety, it shows that the multiplication factor may reach 10, tritium breeding ratio is greater than 1.15, and the blanket keeps in a deep sub-critical state and shows good heat safety performance. Based on the recently available fusion technology, we are striving to achieve the early commercial use of fusion energy and provide a competitive technology options for the sustainable development of China's energy.
In order to achieve tritium self-sustaining and energy amplification of the magnetic confinement fusion reactors, sub-critical blanket and tritium breeding blanket were set around the plasma region. We adopted natural uranium alloy as fuel, light water as coolant and moderator and embedded pressure tube sub-critical blanket as blanket design. By the analysis of neutronic physical properties, structural concept design, thermal-hydraulic performance and reactor safety, it shows that the multiplication factor may reach 10, tritium breeding ratio is greater than 1.15, and the blanket keeps in a deep sub-critical state and shows good heat safety performance. Based on the recently available fusion technology, we are striving to achieve the early commercial use of fusion energy and provide a competitive technology options for the sustainable development of China's energy.
2015,
27: 121001.
doi: 10.11884/HPLPB201527.121001
Abstract:
High energy laser will sharply increase the surface temperature of the absorbers until the surfaces of them are damaged, meanwhile, there is a large temperature gradient for a long time, which makes it difficult to accurately measure the temperature of the absorbers. In order to solve this problem, this paper presents a stepped gilded-reflection-cone absorber with V-grooves. Energy was allocated to various parts of the absorbent body with the design of gilded cone, the effects of two designs of V-groove absorber on the temperature field and the surface temperature were studied. It is shown that the temperature gradient of each part of the absorber, the surface temperature and the equilibration time were decreased by controlling the quality of the absorbers and parameters of the V-cone absorbers, so as to improve laser damage threshold of high-energy laser energy meter and reduce the difficulty of temperature measurement and heat loss, and ultimately improve the accuracy of measurement.
High energy laser will sharply increase the surface temperature of the absorbers until the surfaces of them are damaged, meanwhile, there is a large temperature gradient for a long time, which makes it difficult to accurately measure the temperature of the absorbers. In order to solve this problem, this paper presents a stepped gilded-reflection-cone absorber with V-grooves. Energy was allocated to various parts of the absorbent body with the design of gilded cone, the effects of two designs of V-groove absorber on the temperature field and the surface temperature were studied. It is shown that the temperature gradient of each part of the absorber, the surface temperature and the equilibration time were decreased by controlling the quality of the absorbers and parameters of the V-cone absorbers, so as to improve laser damage threshold of high-energy laser energy meter and reduce the difficulty of temperature measurement and heat loss, and ultimately improve the accuracy of measurement.
2015,
27: 121002.
doi: 10.11884/HPLPB201527.121002
Abstract:
A laser output process monitoring method for the chemical oxygen iodine laser (COIL) is proposed based on the kernel principal component analysis (KPCA), which is well suit for the analysis of stable non-linear process. Based on the expansion of normal laser output data along the time axis, temporal KPCA models are established using this method. Furthermore, the T2 and SPE parameters are established in eigenspace to monitor laser output process. The feasibility of the monitoring method, which can detects various abnormal states of the laser output process promptly and accurately, is verified by theoretical simulations and experimental tests.
A laser output process monitoring method for the chemical oxygen iodine laser (COIL) is proposed based on the kernel principal component analysis (KPCA), which is well suit for the analysis of stable non-linear process. Based on the expansion of normal laser output data along the time axis, temporal KPCA models are established using this method. Furthermore, the T2 and SPE parameters are established in eigenspace to monitor laser output process. The feasibility of the monitoring method, which can detects various abnormal states of the laser output process promptly and accurately, is verified by theoretical simulations and experimental tests.
2015,
27: 121003.
doi: 10.11884/HPLPB201527.121003
Abstract:
It is difficult to coat photoresist uniformly on large plates for diffraction optics component fabrication. The relationship between photoresist thickness and scan velocity is experimentally explored by a small meniscus coating applicator. Aside from the thickness, the distribution uniformity of the thickness is also important and is experimentally found it is mainly dependent on system stability. Firstly, the relationship between the thickness uniformity and the scan velocity is explored and optimized. Secondly, interspace variations during the scan process with different coating parameters are measured in situ using a non-contact laser triangulation sensor, it is limited to 15 m in the scan process. Several variation reduction measures are adopted. After parameter optimization and system improvement, the photoresist is uniformly coated with a peak-to-valley (PV) value of 3% and a root-mean-square deviation of 0.5% to fabricate diffractive optic plates.
It is difficult to coat photoresist uniformly on large plates for diffraction optics component fabrication. The relationship between photoresist thickness and scan velocity is experimentally explored by a small meniscus coating applicator. Aside from the thickness, the distribution uniformity of the thickness is also important and is experimentally found it is mainly dependent on system stability. Firstly, the relationship between the thickness uniformity and the scan velocity is explored and optimized. Secondly, interspace variations during the scan process with different coating parameters are measured in situ using a non-contact laser triangulation sensor, it is limited to 15 m in the scan process. Several variation reduction measures are adopted. After parameter optimization and system improvement, the photoresist is uniformly coated with a peak-to-valley (PV) value of 3% and a root-mean-square deviation of 0.5% to fabricate diffractive optic plates.
2015,
27: 121004.
doi: 10.11884/HPLPB201527.121004
Abstract:
A method is introduced for detecting approximately-circular object in infrared image by using the multi-feature joint probability. Bending direction of short-length curves in the image is calculated to get the directing probability of circles existing at each pixel. Edge intensity in gradient image is used to weight the probability, which is then combined with the probability of hole existing at each position and get a final judge whether or where the approximate-circular objects occur. The method shows some advantages when compared with the resolution from Hough transformation. Experiments with some quite different infrared images show that the method can successfully detect approximately-circular objects and shows good stability, so it is useful for target detection and recognition in some application.
A method is introduced for detecting approximately-circular object in infrared image by using the multi-feature joint probability. Bending direction of short-length curves in the image is calculated to get the directing probability of circles existing at each pixel. Edge intensity in gradient image is used to weight the probability, which is then combined with the probability of hole existing at each position and get a final judge whether or where the approximate-circular objects occur. The method shows some advantages when compared with the resolution from Hough transformation. Experiments with some quite different infrared images show that the method can successfully detect approximately-circular objects and shows good stability, so it is useful for target detection and recognition in some application.
2015,
27: 121005.
doi: 10.11884/HPLPB201527.121005
Abstract:
In this paper, we demonstrated a broadly tunable MgO:PPLN mid-infrared optical parametric oscillator(OPO) synchronously pumped by a picosecond(ps) Innoslab amplifier. The signal wavelength tuning range from 1415 nm to 1557 nm and idler from 3362 nm to 4290 nm were achieved by changing the temperature and translating the grating of the MgO:PPLN, within which the highest optical-optical conversion efficiency from pump power to OPO output was 17.5%.Under the synchronously pumping power of 16 W with 116.9 MHz pulse repetition rate, 1.33 W of signal light at 1518 nm and 1.26 W of idler light at 3558 nm were obtained simultaneously.
In this paper, we demonstrated a broadly tunable MgO:PPLN mid-infrared optical parametric oscillator(OPO) synchronously pumped by a picosecond(ps) Innoslab amplifier. The signal wavelength tuning range from 1415 nm to 1557 nm and idler from 3362 nm to 4290 nm were achieved by changing the temperature and translating the grating of the MgO:PPLN, within which the highest optical-optical conversion efficiency from pump power to OPO output was 17.5%.Under the synchronously pumping power of 16 W with 116.9 MHz pulse repetition rate, 1.33 W of signal light at 1518 nm and 1.26 W of idler light at 3558 nm were obtained simultaneously.
2015,
27: 121006.
doi: 10.11884/HPLPB201527.121006
Abstract:
Liquid tank is a potential part irradiated by laser in laser-matter interaction research. In this paper, laser irradiation effects on a water tank were investigated by experiments and numerical simulations on the condition that the water was in a natural convection state. The irradiation mechanisms are described as follows: at the initial stage of laser irradiation, the center region of the aluminum wall had an obvious temperature increase due to laser heating, and the temperature of the water near the wall also had a slight increase. With the time evolution, the water temperature became larger and higher, and the magnitude of the max velocity on the line, which was perpendicular to the plate and passed through the laser spot center, kept on increasing in response to the temperature increase, thus the heat transfer intensity continued increasing. With the increase of the heat transfer intensity, the temperature rise rate of the aluminum wall decreased gradually. When the energy absorbed by the wall could be taken away by the water natural convection, the temperature rise rate of the plate center approached zero.
Liquid tank is a potential part irradiated by laser in laser-matter interaction research. In this paper, laser irradiation effects on a water tank were investigated by experiments and numerical simulations on the condition that the water was in a natural convection state. The irradiation mechanisms are described as follows: at the initial stage of laser irradiation, the center region of the aluminum wall had an obvious temperature increase due to laser heating, and the temperature of the water near the wall also had a slight increase. With the time evolution, the water temperature became larger and higher, and the magnitude of the max velocity on the line, which was perpendicular to the plate and passed through the laser spot center, kept on increasing in response to the temperature increase, thus the heat transfer intensity continued increasing. With the increase of the heat transfer intensity, the temperature rise rate of the aluminum wall decreased gradually. When the energy absorbed by the wall could be taken away by the water natural convection, the temperature rise rate of the plate center approached zero.
2015,
27: 121007.
doi: 10.11884/HPLPB201527.121007
Abstract:
This paper presents a continuous wave exciplex pumped alkali laser (XPAL) four-level theoretical model ,which can simulate the pump threshold. The model is based on rate equation and calculated by the iterative algorithm. The pump threshold characteristics of CW pumped four-level XPAL system can be analyzed by this model. The analysis of the influences of temperature, the length of the vapor cell, linewidth of pumped laser, output coupler and the concentration of noble gas on pump threshold are presented. It is shown that there is an optimal temperature which will keep a low threshold. In addition, the analysis of the length of cell, output coupler, linewidth of pumped laser and the concentration of noble gas shows that the influence of the concentration of noble gas on the pump threshold is larger than other factors. Larger concentration of noble gas can increase the absorption of pump laser in gain medium.
This paper presents a continuous wave exciplex pumped alkali laser (XPAL) four-level theoretical model ,which can simulate the pump threshold. The model is based on rate equation and calculated by the iterative algorithm. The pump threshold characteristics of CW pumped four-level XPAL system can be analyzed by this model. The analysis of the influences of temperature, the length of the vapor cell, linewidth of pumped laser, output coupler and the concentration of noble gas on pump threshold are presented. It is shown that there is an optimal temperature which will keep a low threshold. In addition, the analysis of the length of cell, output coupler, linewidth of pumped laser and the concentration of noble gas shows that the influence of the concentration of noble gas on the pump threshold is larger than other factors. Larger concentration of noble gas can increase the absorption of pump laser in gain medium.
2015,
27: 121008.
doi: 10.11884/HPLPB201527.121008
Abstract:
To solve the problem that tool paths will bring iterative errors in the process of magnetorheological polishing, an adaptive polishing path method is proposed, in which the step size can be adjusted according to the optical surface gradient. Firstly, according to the distribution of the original surface errors, all the gradient values at each point can be obtained and will be classified based on the discrete gradient clustering. Then a tool path that both the row and column step size can be adjusted with respect to the surface errors is obtained. Experiments on the home-made magnetorheological finishing machine MRP-1200M successfully process a 50 mm diameter microcrystalline glass, from 65 nm(PV) and 12 nm(RMS) to 21 nm(PV) and 2.5 nm(RMS) without obvious peak error in the power spectral density curve after processing. Experimental results show that this adaptive tool path can effectively suppress the mid-spatial errors and the high-spatial errors.
To solve the problem that tool paths will bring iterative errors in the process of magnetorheological polishing, an adaptive polishing path method is proposed, in which the step size can be adjusted according to the optical surface gradient. Firstly, according to the distribution of the original surface errors, all the gradient values at each point can be obtained and will be classified based on the discrete gradient clustering. Then a tool path that both the row and column step size can be adjusted with respect to the surface errors is obtained. Experiments on the home-made magnetorheological finishing machine MRP-1200M successfully process a 50 mm diameter microcrystalline glass, from 65 nm(PV) and 12 nm(RMS) to 21 nm(PV) and 2.5 nm(RMS) without obvious peak error in the power spectral density curve after processing. Experimental results show that this adaptive tool path can effectively suppress the mid-spatial errors and the high-spatial errors.
2015,
27: 122001.
doi: 10.11884/HPLPB201527.122001
Abstract:
A Ross filter spectrometer, consisting of 7 energy channels and covering 18-88 keV energy range, was designed by calculation with the optimization goal of band-pass flat response, in which the residual response, relative error outside the energy channels and flatness inside energy channels were used to optimize the thickness of the filters. The energy channel width of the spectrometer was between 2 keV and 20 keV. The relative error and flatness were lower than 10% and 20% respectively for most energy channels. This spectrometer was applied to experiments performed on a microfocus X-ray tube in which high-energy X-ray was used to backlit spherical shell samples made of high-Z metals. The results show that, under different experimental conditions, spectra measured by Ross filter spectrometer were in agreement with theory models. The measured spectra interpreted the images quite well and could be used to obtain areal density from the images.
A Ross filter spectrometer, consisting of 7 energy channels and covering 18-88 keV energy range, was designed by calculation with the optimization goal of band-pass flat response, in which the residual response, relative error outside the energy channels and flatness inside energy channels were used to optimize the thickness of the filters. The energy channel width of the spectrometer was between 2 keV and 20 keV. The relative error and flatness were lower than 10% and 20% respectively for most energy channels. This spectrometer was applied to experiments performed on a microfocus X-ray tube in which high-energy X-ray was used to backlit spherical shell samples made of high-Z metals. The results show that, under different experimental conditions, spectra measured by Ross filter spectrometer were in agreement with theory models. The measured spectra interpreted the images quite well and could be used to obtain areal density from the images.
2015,
27: 122002.
doi: 10.11884/HPLPB201527.122002
Abstract:
The studies of inertial confinement fusion (ICF) propose increasing demands for high precision detection devices. This paper is mainly about the studies on a novel optical streak camera with ultrahigh time resolution based on the photo-generated carrier effects, in which the key technology, the design of the optical scanning module and the temporal synchronization between the pump light and the signal light, will deeply influence the performance of the optical scanning module. The experimental results show that the deflection of the signal light increases with the power density of the pump light, which confirms the feasibility of the designed optical scanning module. The temporal synchronization will also influence the deflection of the signal light, which means that the temporal synchronization will finally determine the temporal resolution of the optical scanning device. The studies in this paper can well support the next studies on the time-to-space conversion of ultra-short signal light.
The studies of inertial confinement fusion (ICF) propose increasing demands for high precision detection devices. This paper is mainly about the studies on a novel optical streak camera with ultrahigh time resolution based on the photo-generated carrier effects, in which the key technology, the design of the optical scanning module and the temporal synchronization between the pump light and the signal light, will deeply influence the performance of the optical scanning module. The experimental results show that the deflection of the signal light increases with the power density of the pump light, which confirms the feasibility of the designed optical scanning module. The temporal synchronization will also influence the deflection of the signal light, which means that the temporal synchronization will finally determine the temporal resolution of the optical scanning device. The studies in this paper can well support the next studies on the time-to-space conversion of ultra-short signal light.
2015,
27: 122003.
doi: 10.11884/HPLPB201527.122003
Abstract:
Micro-machining is the most effective method for KDP crystal to mitigate the surface damage growth in high power laser systems. In this work, spherical and Gaussian mitigation pits are fabricated by micro-milling with an efficient machining procedure. The light intensification caused by front-surface features after mitigation is numerically modeled based on the finite element method (FEM) for acquiring the optimal structural parameters of mitigation pits. The results indicate that the occurrence of diffraction from the pits is principally responsible for the light intensification inside the crystal, and the interference from the second incident laser on the pits fringe results in the light intensification, which unsteady increases with the decreasing of the pits wide-depth ratio. For spherical and Gaussian pits after mitigation, it is suggested that the width-depth ratio of spherical mitigation pit should be devised to be larger than 5.0 to avoid the second incident light, achieving the minimal light intensification for the mitigation of surface damage growth. When the wide-depth ratio of the mitigation pit is larger than 10.0, Gaussian contour is preferred to achieve better repairing quality. The laser damage test on the mitigation pits with 1000 m-width and 20 m-depth has effectively verified the simulation results.
Micro-machining is the most effective method for KDP crystal to mitigate the surface damage growth in high power laser systems. In this work, spherical and Gaussian mitigation pits are fabricated by micro-milling with an efficient machining procedure. The light intensification caused by front-surface features after mitigation is numerically modeled based on the finite element method (FEM) for acquiring the optimal structural parameters of mitigation pits. The results indicate that the occurrence of diffraction from the pits is principally responsible for the light intensification inside the crystal, and the interference from the second incident laser on the pits fringe results in the light intensification, which unsteady increases with the decreasing of the pits wide-depth ratio. For spherical and Gaussian pits after mitigation, it is suggested that the width-depth ratio of spherical mitigation pit should be devised to be larger than 5.0 to avoid the second incident light, achieving the minimal light intensification for the mitigation of surface damage growth. When the wide-depth ratio of the mitigation pit is larger than 10.0, Gaussian contour is preferred to achieve better repairing quality. The laser damage test on the mitigation pits with 1000 m-width and 20 m-depth has effectively verified the simulation results.
2015,
27: 122004.
doi: 10.11884/HPLPB201527.122004
Abstract:
By using chemical vapor deposition-depolymerizable mandrel method, hollow glass microspheres for inertial confinement fusion targets were fabricated at different coating pressure. Surface roughness, sphericity, wall thickness uniformity and composition were measured by scanning electron microscope, atomic force microscope, VMR microscope and energy dispersive spectrometer, respectively. The results show that as the coating pressure increases, the surface roughness of the hollow glass microsphere and the carbon concentration decrease, while the wall thickness uniformity and the silicon concentration of the hollow glass microspheres increase.
By using chemical vapor deposition-depolymerizable mandrel method, hollow glass microspheres for inertial confinement fusion targets were fabricated at different coating pressure. Surface roughness, sphericity, wall thickness uniformity and composition were measured by scanning electron microscope, atomic force microscope, VMR microscope and energy dispersive spectrometer, respectively. The results show that as the coating pressure increases, the surface roughness of the hollow glass microsphere and the carbon concentration decrease, while the wall thickness uniformity and the silicon concentration of the hollow glass microspheres increase.
2015,
27: 122005.
doi: 10.11884/HPLPB201527.122005
Abstract:
The optical emission spectroscopy(OES) is an effective method for plasma diagnosing. In this article, OES was used to in situ measure the hot filament chemical vapor deposition(HFCVD) plasma of acetone/H2 system, acetone/H2/He system and acetone/H2/Ar system respectively. The intensity of radicals, the intensity ratios of CH, H to C2 and the value of electron temperature as a function of inert gas volume fraction were studied. The result shows that the spectrum intensities of radicals increase with the increasing of the inert gas volume fraction, and the influence of argon is much higher than that of helium. The intensity ratios of CH, H to C2 and the value of electron temperature decrease with the increasing concentration of the inert gas in the feed gas. The intensity ratio of CH/C2, H/C2 and the value of electron temperature are higher in the acetone/H2/He system than that in the acetone/H2/Ar system.
The optical emission spectroscopy(OES) is an effective method for plasma diagnosing. In this article, OES was used to in situ measure the hot filament chemical vapor deposition(HFCVD) plasma of acetone/H2 system, acetone/H2/He system and acetone/H2/Ar system respectively. The intensity of radicals, the intensity ratios of CH, H to C2 and the value of electron temperature as a function of inert gas volume fraction were studied. The result shows that the spectrum intensities of radicals increase with the increasing of the inert gas volume fraction, and the influence of argon is much higher than that of helium. The intensity ratios of CH, H to C2 and the value of electron temperature decrease with the increasing concentration of the inert gas in the feed gas. The intensity ratio of CH/C2, H/C2 and the value of electron temperature are higher in the acetone/H2/He system than that in the acetone/H2/Ar system.
2015,
27: 122006.
doi: 10.11884/HPLPB201527.122006
Abstract:
The CsI(Tl) scintillator is a key part for the transition from X-ray to visible light in X-ray detectors, which is of crucial importance in X-ray diagnosis for inertial confined fusion. Geant4 is used to imitate the mechanism of the energy deposition of X-ray in the CsI(Tl) scintillator. 1-5 keV X-rays could deposit energies into the CsI(Tl) scintillator with different thickness(20, 30, or 50 m). The deposition energy and deposition efficiency are compared. The results show that the deposition energy increases with the increase of CsI(Tl) scintillator thickness. This theoretically investigation has provided valid proofs for the preparation of the forthcoming experimental study.
The CsI(Tl) scintillator is a key part for the transition from X-ray to visible light in X-ray detectors, which is of crucial importance in X-ray diagnosis for inertial confined fusion. Geant4 is used to imitate the mechanism of the energy deposition of X-ray in the CsI(Tl) scintillator. 1-5 keV X-rays could deposit energies into the CsI(Tl) scintillator with different thickness(20, 30, or 50 m). The deposition energy and deposition efficiency are compared. The results show that the deposition energy increases with the increase of CsI(Tl) scintillator thickness. This theoretically investigation has provided valid proofs for the preparation of the forthcoming experimental study.
Effect of Tween 20 nonionic surfactant on preparation of large size double-layer hollow microspheres
2015,
27: 122007.
doi: 10.11884/HPLPB201527.122007
Abstract:
The investigation of the preparation technique of polymeric hollow microsphere is very important for the fuel container of inertial confinement fusion (ICF). The 1% of Tween 20 (T-20) nonionic surfactant is used to modify ozonated polystyrenes microspheres to improve the dispersion of the polystyrene-polyvinylalcohol (PS-PVA) double-layer emulsion microspheres in oil phase and to enhance the survival rate of large size double microspheres. The T-20 treated PS single-layer microspheres are subsequently immersed into PVA solution and encapsulated by PVA. Then the curing technique is used to ensure the fabrication of monodispersed PS-PVA double-layer emulsion microspheres. The results reveal that the contact angle of PS film can be obviously decreased due to the T-20 surface modification of PS. In addition, both the interaction between PS and PVA and the absorption rate of PS film to PVA are greatly enhanced. The infrared spectroscopy and ultraviolet spectroscopy results show that part of absorbed T-20 surfactant on PS surface is replaced by PVA and immigrates into PVA solution in the curing procedure of PVA because of the large dimension of PVA macromolecular. The immigration of T-20 results in the increase of the viscosity ratio of water phase to oil phase and the obviously decrease of the surface tension for PVA during the process of fabricating double-layer emulsion microspheres. The dispersion of PS-PVA double microspheres in oil phase is also improved. The survival rate of large size double-layer hollow microspheres after modified by T-20 remarkably increases to 50%. Therefore, the T-20 is efficient nonionic surfactant in preparing large size PS-PVA double-layer hollow microspheres.
The investigation of the preparation technique of polymeric hollow microsphere is very important for the fuel container of inertial confinement fusion (ICF). The 1% of Tween 20 (T-20) nonionic surfactant is used to modify ozonated polystyrenes microspheres to improve the dispersion of the polystyrene-polyvinylalcohol (PS-PVA) double-layer emulsion microspheres in oil phase and to enhance the survival rate of large size double microspheres. The T-20 treated PS single-layer microspheres are subsequently immersed into PVA solution and encapsulated by PVA. Then the curing technique is used to ensure the fabrication of monodispersed PS-PVA double-layer emulsion microspheres. The results reveal that the contact angle of PS film can be obviously decreased due to the T-20 surface modification of PS. In addition, both the interaction between PS and PVA and the absorption rate of PS film to PVA are greatly enhanced. The infrared spectroscopy and ultraviolet spectroscopy results show that part of absorbed T-20 surfactant on PS surface is replaced by PVA and immigrates into PVA solution in the curing procedure of PVA because of the large dimension of PVA macromolecular. The immigration of T-20 results in the increase of the viscosity ratio of water phase to oil phase and the obviously decrease of the surface tension for PVA during the process of fabricating double-layer emulsion microspheres. The dispersion of PS-PVA double microspheres in oil phase is also improved. The survival rate of large size double-layer hollow microspheres after modified by T-20 remarkably increases to 50%. Therefore, the T-20 is efficient nonionic surfactant in preparing large size PS-PVA double-layer hollow microspheres.
2015,
27: 122008.
doi: 10.11884/HPLPB201527.122008
Abstract:
Numerical calculation model of beam smoothing is established based on scalar diffraction theory. The model takes account of smoothing by spectral dispersion (SSD), random phase plate (RPP), and polarization smoothing (PS). Effect of radial polarization modulation on smoothing and polarization properties of focal speckle is studied based on the model. Speckle contrast and polarization degree are used to characterize smoothing and polarization properties, respectively. The results show that contrast and polarization degree of focal speckle can be reduced by radial polarization modulation. Approximately radially polarized beam can be generated by polarization control plate (PCP) made by jointing several half-wave plates. The influence on smoothing and polarization properties of the number of half-wave plates is relatively small. Actually, the effect of an approximately radially polarized beam generated by 8 half-wave plates is nearly the same as that of a perfectly radially polarized beam. Three methods for polarization smoothing (radial polarization modulation, orthogonal polarization modulation and using birefringent wedge) are analyzed and compared, and the results show that the effects of the three methods are similar.
Numerical calculation model of beam smoothing is established based on scalar diffraction theory. The model takes account of smoothing by spectral dispersion (SSD), random phase plate (RPP), and polarization smoothing (PS). Effect of radial polarization modulation on smoothing and polarization properties of focal speckle is studied based on the model. Speckle contrast and polarization degree are used to characterize smoothing and polarization properties, respectively. The results show that contrast and polarization degree of focal speckle can be reduced by radial polarization modulation. Approximately radially polarized beam can be generated by polarization control plate (PCP) made by jointing several half-wave plates. The influence on smoothing and polarization properties of the number of half-wave plates is relatively small. Actually, the effect of an approximately radially polarized beam generated by 8 half-wave plates is nearly the same as that of a perfectly radially polarized beam. Three methods for polarization smoothing (radial polarization modulation, orthogonal polarization modulation and using birefringent wedge) are analyzed and compared, and the results show that the effects of the three methods are similar.
2015,
27: 123001.
doi: 10.11884/HPLPB201527.123001
Abstract:
Two input/output couplers consisting of multiple apertures in E plane and H plane are designed and analyzed for a W-band broadband sheet beam traveling wave tube (TWT). Multi-apertures are adopted in the couplers to separate the electromagnetic field from the beam and extend the operating bandwidth. Simulation results optimized by HFSS indicate that the E-plane coupler can achieve a 1 dB transmission bandwidth of 45.3% and a -20 dB isolation bandwidth of 34.7% respectively. Similar results are obtained by adding two more apertures for the H-plane coupler, specifically, the 1 dB relative bandwidth and the port isolation under -15 dB can get improved to 45.3% and 30.6% respectively. Both novel couplers can achieve high isolation and low reflection in extreme broad bandwidth. In comparison with the E plane coupler, the H plane structure is easy to fabricate, cool and integrate with periodic permanent magnet in compact dimensions.
Two input/output couplers consisting of multiple apertures in E plane and H plane are designed and analyzed for a W-band broadband sheet beam traveling wave tube (TWT). Multi-apertures are adopted in the couplers to separate the electromagnetic field from the beam and extend the operating bandwidth. Simulation results optimized by HFSS indicate that the E-plane coupler can achieve a 1 dB transmission bandwidth of 45.3% and a -20 dB isolation bandwidth of 34.7% respectively. Similar results are obtained by adding two more apertures for the H-plane coupler, specifically, the 1 dB relative bandwidth and the port isolation under -15 dB can get improved to 45.3% and 30.6% respectively. Both novel couplers can achieve high isolation and low reflection in extreme broad bandwidth. In comparison with the E plane coupler, the H plane structure is easy to fabricate, cool and integrate with periodic permanent magnet in compact dimensions.
2015,
27: 123002.
doi: 10.11884/HPLPB201527.123002
Abstract:
A circular waveguide TE11-HE11 mode transducing antenna loaded with radial double mediums is reported based on measurements and simulations. The mode transducing antenna includes a novel broadband circular waveguide TE11-HE11 mode converter and a radiator. The circular waveguide TE11-HE11 mode converter is inserted with radial double mediums, and the radiator adopting an open circular waveguide or a small angle conical horn will radiate out HE11 mode. Using the commercial software HFSS to simulate and optimize two kinds of circular waveguide TE11-HE11 mode transducing antennas, the numerical results show that the two antennas have a highly symmetrical radiation pattern and a relatively low sidelobe level, no matter they work at linear polarization or circular polarization. The standing wave ratio (VSWR) and the gain of the two kinds of mode transducing antennas are tested by using the vector network analyzer and the spectrum analyzer. The measured results reveal that the gain of the antenna which uses an open-ended circular waveguide as the radiator is 11.21 dB, the gain of the antenna which uses a small angle conical horn as the radiator is 15.58 dB, and the VSWR is less than 1.05 at the center frequency of 9.4 GHz. The experimental results are in agreement with the simulation results, which validates the feasibility and correctness of the antenna technology of the mode conversion.
A circular waveguide TE11-HE11 mode transducing antenna loaded with radial double mediums is reported based on measurements and simulations. The mode transducing antenna includes a novel broadband circular waveguide TE11-HE11 mode converter and a radiator. The circular waveguide TE11-HE11 mode converter is inserted with radial double mediums, and the radiator adopting an open circular waveguide or a small angle conical horn will radiate out HE11 mode. Using the commercial software HFSS to simulate and optimize two kinds of circular waveguide TE11-HE11 mode transducing antennas, the numerical results show that the two antennas have a highly symmetrical radiation pattern and a relatively low sidelobe level, no matter they work at linear polarization or circular polarization. The standing wave ratio (VSWR) and the gain of the two kinds of mode transducing antennas are tested by using the vector network analyzer and the spectrum analyzer. The measured results reveal that the gain of the antenna which uses an open-ended circular waveguide as the radiator is 11.21 dB, the gain of the antenna which uses a small angle conical horn as the radiator is 15.58 dB, and the VSWR is less than 1.05 at the center frequency of 9.4 GHz. The experimental results are in agreement with the simulation results, which validates the feasibility and correctness of the antenna technology of the mode conversion.
2015,
27: 123003.
doi: 10.11884/HPLPB201527.123003
Abstract:
The traditional diagnosis and tuning method for microwave filter only extract, the equivalent circuit parameters, but not the tuning magnitude. The couplings between the tuning elements are not considered, and it is very inefficient. In order to diagnos and tune the microwave filter quickly, we must determine the tuning direction and value. An improved tuning method based on genetic algorithm and aggressive space mapping is presented in this paper. The measured or simulated parameters such as S parameters are not suitable for parameter extraction directly. The phase shift effect must be removed before parameter extraction. The phase shift effect is moved by using the genetic algorithm. The equivalent circuit parameters are extracted through Cauchy method after the phase shift effect is removed. The tuning direction and value are determined by aggressive space mapping, which makes the filter meet the specifications. A fourth order cross-coupled filter tuning example is used to verify the new method and shows the validity of the method. The filter meets specifications less than four iterations. The method presented in this paper can be applied to other type filter diagnosis and tuning.
The traditional diagnosis and tuning method for microwave filter only extract, the equivalent circuit parameters, but not the tuning magnitude. The couplings between the tuning elements are not considered, and it is very inefficient. In order to diagnos and tune the microwave filter quickly, we must determine the tuning direction and value. An improved tuning method based on genetic algorithm and aggressive space mapping is presented in this paper. The measured or simulated parameters such as S parameters are not suitable for parameter extraction directly. The phase shift effect must be removed before parameter extraction. The phase shift effect is moved by using the genetic algorithm. The equivalent circuit parameters are extracted through Cauchy method after the phase shift effect is removed. The tuning direction and value are determined by aggressive space mapping, which makes the filter meet the specifications. A fourth order cross-coupled filter tuning example is used to verify the new method and shows the validity of the method. The filter meets specifications less than four iterations. The method presented in this paper can be applied to other type filter diagnosis and tuning.
2015,
27: 123004.
doi: 10.11884/HPLPB201527.123004
Abstract:
The design of an iris cavity for a W-band third harmonic gyrotron is presented. The gyrotron is designed to operate at the low loss, circular symmetric TE02 mode. The minimum start current is 2.9 A and the ohmic efficiency is 67%. When the gyrotron is driven by a 45 kV, 4 A electron beam with an orbital-to-axial velocity ratio equal to 1.5, an output power of 25.7 kW at 94.8 GHz is predicted from PIC simulation, corresponding to an efficiency of 14.3%.
The design of an iris cavity for a W-band third harmonic gyrotron is presented. The gyrotron is designed to operate at the low loss, circular symmetric TE02 mode. The minimum start current is 2.9 A and the ohmic efficiency is 67%. When the gyrotron is driven by a 45 kV, 4 A electron beam with an orbital-to-axial velocity ratio equal to 1.5, an output power of 25.7 kW at 94.8 GHz is predicted from PIC simulation, corresponding to an efficiency of 14.3%.
2015,
27: 123005.
doi: 10.11884/HPLPB201527.123005
Abstract:
In view of the strong correlation between amplitude and phase characteristics of Traveling Wave Tube Amplifier (TWTA) analog predistortion technology, a dual-branch vector synthesis predistortion linearizer is proposed, which consists of branch line hybrid couplers, an adjustable attenuator and a reflective diode-based predistortion circuit. This linearizer is fabricated and measured according to the theoretical analysis and simulation results. The measurement results show that the linearizer can compensate the nonlinearity of the TWTAs. Once the two branches bias voltages are rationalized, the phase expansion can change 30 degrees, while the change of the amplitude expansion is less than 1 dB, which effectively reduces the correlation between the amplitude and the phase characteristics of the analog predistortion linearizer.
In view of the strong correlation between amplitude and phase characteristics of Traveling Wave Tube Amplifier (TWTA) analog predistortion technology, a dual-branch vector synthesis predistortion linearizer is proposed, which consists of branch line hybrid couplers, an adjustable attenuator and a reflective diode-based predistortion circuit. This linearizer is fabricated and measured according to the theoretical analysis and simulation results. The measurement results show that the linearizer can compensate the nonlinearity of the TWTAs. Once the two branches bias voltages are rationalized, the phase expansion can change 30 degrees, while the change of the amplitude expansion is less than 1 dB, which effectively reduces the correlation between the amplitude and the phase characteristics of the analog predistortion linearizer.
2015,
27: 123006.
doi: 10.11884/HPLPB201527.123006
Abstract:
In view of the strong correlation between amplitude and phase characteristics of Traveling Wave Tube Amplifier (TWTA) analog predistortion technology, a dual-branch vector synthesis predistortion linearizer is proposed, which consists of branch line hybrid couplers, an adjustable attenuator and a reflective diode-based predistortion circuit. This linearizer is fabricated and measured according to the theoretical analysis and simulation results. The measurement results show that the linearizer can compensate the nonlinearity of the TWTAs. Once the two branches bias voltages are rationalized, the phase expansion can change 30 degrees, while the change of the amplitude expansion is less than 1 dB, which effectively reduces the correlation between the amplitude and the phase characteristics of the analog predistortion linearizer.
In view of the strong correlation between amplitude and phase characteristics of Traveling Wave Tube Amplifier (TWTA) analog predistortion technology, a dual-branch vector synthesis predistortion linearizer is proposed, which consists of branch line hybrid couplers, an adjustable attenuator and a reflective diode-based predistortion circuit. This linearizer is fabricated and measured according to the theoretical analysis and simulation results. The measurement results show that the linearizer can compensate the nonlinearity of the TWTAs. Once the two branches bias voltages are rationalized, the phase expansion can change 30 degrees, while the change of the amplitude expansion is less than 1 dB, which effectively reduces the correlation between the amplitude and the phase characteristics of the analog predistortion linearizer.
2015,
27: 123007.
doi: 10.11884/HPLPB201527.123007
Abstract:
This paper presents a new measuring method of minimizing the impact of ground reflection on the microwave electronic field measurement using double antenna array. The character of ground reflection is studied using the electromagnetic geometric optics theory and the electromagnetic wave propagation formula in layered media. Then a theoretical formula for computing the oscillating period of ground scattering pattern is derived. The impact of ground reflection on the transversal field and vertical field is simulated using the FDTD method, and the effect of minimizing the ground reflection with double antenna array is also validated by simulation, it shows that the impact of ground reflection is decreased from 4 dB to less than 0.6 dB, which improves the accuracy of the high power microwave radiation field measurement.
This paper presents a new measuring method of minimizing the impact of ground reflection on the microwave electronic field measurement using double antenna array. The character of ground reflection is studied using the electromagnetic geometric optics theory and the electromagnetic wave propagation formula in layered media. Then a theoretical formula for computing the oscillating period of ground scattering pattern is derived. The impact of ground reflection on the transversal field and vertical field is simulated using the FDTD method, and the effect of minimizing the ground reflection with double antenna array is also validated by simulation, it shows that the impact of ground reflection is decreased from 4 dB to less than 0.6 dB, which improves the accuracy of the high power microwave radiation field measurement.
2015,
27: 123008.
doi: 10.11884/HPLPB201527.123008
Abstract:
In the circular symmetrical magnetic field, the annular electron beam impacts on the cylindrical relativistic backward-wave oscillator (RBWO), in which the energy of the electrons are deposited. The model of the electron energy deposition is built with Monte Carlo code FLUKA, and the distribution of the electron energy deposition is studied. The motion model for the backscattering electron is built and the electron trajectory in magnetic field is simulated. The method for approximating the circular symmetrical magnetic field is developed. Several conclusions are made as follows: with the magnetic field enhanced, the maximal energy deposition density becomes larger, and the position of the backscattering electron is nearer to the incident electrons region and a new energy deposition peak may occur. When the magnetic field is strong enough, the unidirectional magnetic field could be applied to the calculation of the energy deposition distribution under circular symmetrical magnetic field.
In the circular symmetrical magnetic field, the annular electron beam impacts on the cylindrical relativistic backward-wave oscillator (RBWO), in which the energy of the electrons are deposited. The model of the electron energy deposition is built with Monte Carlo code FLUKA, and the distribution of the electron energy deposition is studied. The motion model for the backscattering electron is built and the electron trajectory in magnetic field is simulated. The method for approximating the circular symmetrical magnetic field is developed. Several conclusions are made as follows: with the magnetic field enhanced, the maximal energy deposition density becomes larger, and the position of the backscattering electron is nearer to the incident electrons region and a new energy deposition peak may occur. When the magnetic field is strong enough, the unidirectional magnetic field could be applied to the calculation of the energy deposition distribution under circular symmetrical magnetic field.
2015,
27: 123101.
doi: 10.11884/HPLPB201527.123101
Abstract:
In order to meet the requirement of THz communication, a 0.34 THz bandpass filter was designed based on thinfilm processing and double screen frequency selective surface(FSS). The frequency characteristics of the FSS filter were analyzed by using the equivalent circuit model and the influence of incident angles on the frequency response characteristics of the designed FSS filter was investigated by simulation. The results show that a better frequency response can be obtained at all the angles below 45 with TE polarization. Finally, a sample of the FSS filter was produced, tested and analyzed. The results indicate that this FSS filter has a good performance.
In order to meet the requirement of THz communication, a 0.34 THz bandpass filter was designed based on thinfilm processing and double screen frequency selective surface(FSS). The frequency characteristics of the FSS filter were analyzed by using the equivalent circuit model and the influence of incident angles on the frequency response characteristics of the designed FSS filter was investigated by simulation. The results show that a better frequency response can be obtained at all the angles below 45 with TE polarization. Finally, a sample of the FSS filter was produced, tested and analyzed. The results indicate that this FSS filter has a good performance.
2015,
27: 123201.
doi: 10.11884/HPLPB201527.123201
Abstract:
In order to analyze the distortion mechanism of the magnetic field inside a long solenoid driven by square wave, the magnetic field distribution inside and outside the solenoid was studied using Maxwells equations. Internal and external electric field, magnetic field model of long solenoid driven by sine wave was established respectively by using Maxwell equations. Magnetic field distribution of long solenoid driven by sine wave was obtained, selecting appropriate boundary conditions of ampere circuit law and law of electromagnetic induction. Then square wave was transformed into the form of multiple sine signals by Fourier transform, and an expression for the magnetic field of solenoid driven by square wave current was obtained. The driving signal square waves frequency effect on magnetic field was emphatically analyzed through the simulation test at last. The conclusions demonstrate that there is distortion in the magnetic field of a solenoid driven by a square wave current. The lower the frequency is and the closer the distance from the axis is, the more square wave features the corresponding magnetic field can acquire.
In order to analyze the distortion mechanism of the magnetic field inside a long solenoid driven by square wave, the magnetic field distribution inside and outside the solenoid was studied using Maxwells equations. Internal and external electric field, magnetic field model of long solenoid driven by sine wave was established respectively by using Maxwell equations. Magnetic field distribution of long solenoid driven by sine wave was obtained, selecting appropriate boundary conditions of ampere circuit law and law of electromagnetic induction. Then square wave was transformed into the form of multiple sine signals by Fourier transform, and an expression for the magnetic field of solenoid driven by square wave current was obtained. The driving signal square waves frequency effect on magnetic field was emphatically analyzed through the simulation test at last. The conclusions demonstrate that there is distortion in the magnetic field of a solenoid driven by a square wave current. The lower the frequency is and the closer the distance from the axis is, the more square wave features the corresponding magnetic field can acquire.
2015,
27: 123202.
doi: 10.11884/HPLPB201527.123202
Abstract:
In order to study the vulnerability SCADA(Supervisory Control And Data Acquisition) system and to protect the system under EMP(electromagnetic pulse), a typical oil gas pipeline simulation system was built up and some experiments were conducted. During data acquiring, communicating and remote controlling, the system was under the threat of a typical HEMP(high altitude electromagnetic pulse) environment with E-field at most 50 kV/m. Based on the experiment results, we found that the EMP had some significant effects on popular pipeline SCADA system. Some basic regular analysis was also performed, the effect phenomenon was observed and the effect threshold data were recorded.
In order to study the vulnerability SCADA(Supervisory Control And Data Acquisition) system and to protect the system under EMP(electromagnetic pulse), a typical oil gas pipeline simulation system was built up and some experiments were conducted. During data acquiring, communicating and remote controlling, the system was under the threat of a typical HEMP(high altitude electromagnetic pulse) environment with E-field at most 50 kV/m. Based on the experiment results, we found that the EMP had some significant effects on popular pipeline SCADA system. Some basic regular analysis was also performed, the effect phenomenon was observed and the effect threshold data were recorded.
2015,
27: 124001.
doi: 10.11884/HPLPB201527.124001
Abstract:
Polymethyl phenyl vinyl siloxane rubber(MPVQ) has excellent performances of resistance of high or low temperatures and vibration abatement, etc., it should have spread application to spacecraft vibration abatement and seal. The total ionizing dose effects of MPVQ have been investigated. The results show that the mechanical properties have different degradation with the increase of the irradiation dose. The dose of 1106 Gy(Si) is the change point for the tensile strength and the tear strength. Lower than this dose, the tensile strength and the tear strength decrease quickly with the increasing dose. Higher than this dose, the tensile strength rebound slightly, presenting a wide U distribution; and the tear strength firstly increase and then decrease with the accumulated dose. The elongation at break and Shore A hardness quickly decrease and increase with the total dose respectively, and finally they are close to saturation. The underlying mechanism of total ionizing dose effects for MPVQ is discussed in terms of radiation crosslinking and radiation degradation.
Polymethyl phenyl vinyl siloxane rubber(MPVQ) has excellent performances of resistance of high or low temperatures and vibration abatement, etc., it should have spread application to spacecraft vibration abatement and seal. The total ionizing dose effects of MPVQ have been investigated. The results show that the mechanical properties have different degradation with the increase of the irradiation dose. The dose of 1106 Gy(Si) is the change point for the tensile strength and the tear strength. Lower than this dose, the tensile strength and the tear strength decrease quickly with the increasing dose. Higher than this dose, the tensile strength rebound slightly, presenting a wide U distribution; and the tear strength firstly increase and then decrease with the accumulated dose. The elongation at break and Shore A hardness quickly decrease and increase with the total dose respectively, and finally they are close to saturation. The underlying mechanism of total ionizing dose effects for MPVQ is discussed in terms of radiation crosslinking and radiation degradation.
2015,
27: 124002.
doi: 10.11884/HPLPB201527.124002
Abstract:
The quality of the mesh model is poor by direct-reconstruction from the industrial CT slice images. This paper proposed a global optimization methods based on implicit surface reconstruction without topology restrictions. In this method, 3D surface model was represented by an implicit function, which was calculated first using point cloud information provided by the model, then iso-surface extraction was employed. As for the large data processing problems, we used the fast Fourier transform to improve the efficiency of the algorithm. Experimental results showed that our algorithm could realize mesh denoising, simplifying, smoothing and hole-filling at one time. Compared with the feature-preserving uniform mesh smoothing algorithm, the presented algorithm could effectively remove noise from meshes within a short time.
The quality of the mesh model is poor by direct-reconstruction from the industrial CT slice images. This paper proposed a global optimization methods based on implicit surface reconstruction without topology restrictions. In this method, 3D surface model was represented by an implicit function, which was calculated first using point cloud information provided by the model, then iso-surface extraction was employed. As for the large data processing problems, we used the fast Fourier transform to improve the efficiency of the algorithm. Experimental results showed that our algorithm could realize mesh denoising, simplifying, smoothing and hole-filling at one time. Compared with the feature-preserving uniform mesh smoothing algorithm, the presented algorithm could effectively remove noise from meshes within a short time.
2015,
27: 124003.
doi: 10.11884/HPLPB201527.124003
Abstract:
In order to make relatively accurate analysis for electromagnetic interference problem occurred in interior circuit of equipment chassis, this paper adopts an analysis method based on field-circuit co-simulation to realize electromagnetic interference effect analysis for chassis the interior circuit by taking chassis interior circuit as an example. It is discovered that the electromagnetic interference may cause the interior circuit to produce some disturbance effects such as logic level flip, which provides a reference for research on operating characteristics of circuit in electromagnetic interference environment.
In order to make relatively accurate analysis for electromagnetic interference problem occurred in interior circuit of equipment chassis, this paper adopts an analysis method based on field-circuit co-simulation to realize electromagnetic interference effect analysis for chassis the interior circuit by taking chassis interior circuit as an example. It is discovered that the electromagnetic interference may cause the interior circuit to produce some disturbance effects such as logic level flip, which provides a reference for research on operating characteristics of circuit in electromagnetic interference environment.
2015,
27: 124004.
doi: 10.11884/HPLPB201527.124004
Abstract:
According to complexity of space ionizing radiation, from study on kinetic of space-ionizing-radiation-induced coloration in glasses, this paper discussed problems faced in performance tests of space-ionizing-radiation-induced coloration in glasses, and a method of performance tests based on kinetic was proposed. Using this method, space radiation induced coloration in the glass serving in a given orbital (perigee 350 km, apogee 425 km, orbital inclination 51.6) were analyzed. It can be seen from the results, after 20 years in the orbital, the blue region optical transmission of the K9-HL glass decreases severely, leading to the glass's turning light yellow, and it certainly will do harm to the glass's usage as a fine optical material. Additionally, the applicability of performance tests of space-ionizing-radiation-induced coloration in glasses using 60Co- ray was discussed. It can be seen from the results, it gives to a large error using 60Co- ray as radiation resource to test space-ionizing-radiation-induced coloration in glasses, and the phenomenon is due to it that 60Co- ray has a large penetration depth in the glass and the relaxation process of color centers is not considered.
According to complexity of space ionizing radiation, from study on kinetic of space-ionizing-radiation-induced coloration in glasses, this paper discussed problems faced in performance tests of space-ionizing-radiation-induced coloration in glasses, and a method of performance tests based on kinetic was proposed. Using this method, space radiation induced coloration in the glass serving in a given orbital (perigee 350 km, apogee 425 km, orbital inclination 51.6) were analyzed. It can be seen from the results, after 20 years in the orbital, the blue region optical transmission of the K9-HL glass decreases severely, leading to the glass's turning light yellow, and it certainly will do harm to the glass's usage as a fine optical material. Additionally, the applicability of performance tests of space-ionizing-radiation-induced coloration in glasses using 60Co- ray was discussed. It can be seen from the results, it gives to a large error using 60Co- ray as radiation resource to test space-ionizing-radiation-induced coloration in glasses, and the phenomenon is due to it that 60Co- ray has a large penetration depth in the glass and the relaxation process of color centers is not considered.
2015,
27: 124005.
doi: 10.11884/HPLPB201527.124005
Abstract:
In this paper, the three-dimensional structure of a lead glass MCP was established under CST Particle Studio environment. The Finite Integration Method and the Monte Carlo Method were combined to simulate the multiplication process of secondary electron both under DC and Gaussian bias voltages. The dynamic distribution curves of charge density of secondary electron cloud along the axis of microchannel were obtained. The results show that the distribution of charge density of secondary electron cloud obeys Gaussian distribution. Under DC bias voltage, the density of secondary electron cloud is gradually increasing during the drift process, when the electron cloud drift to the position near the output electrode, the charge density reaches the maximum. Under Gaussian bias voltage, the pulse width has a decisive effect on the multiplication process of secondary electrons, when the pulse width is wider than the average transit time of secondary electrons, the multiplication process is similar to that under DC bias voltage.
In this paper, the three-dimensional structure of a lead glass MCP was established under CST Particle Studio environment. The Finite Integration Method and the Monte Carlo Method were combined to simulate the multiplication process of secondary electron both under DC and Gaussian bias voltages. The dynamic distribution curves of charge density of secondary electron cloud along the axis of microchannel were obtained. The results show that the distribution of charge density of secondary electron cloud obeys Gaussian distribution. Under DC bias voltage, the density of secondary electron cloud is gradually increasing during the drift process, when the electron cloud drift to the position near the output electrode, the charge density reaches the maximum. Under Gaussian bias voltage, the pulse width has a decisive effect on the multiplication process of secondary electrons, when the pulse width is wider than the average transit time of secondary electrons, the multiplication process is similar to that under DC bias voltage.
2015,
27: 124006.
doi: 10.11884/HPLPB201527.124006
Abstract:
Atomic oxygen (AO), near ultraviolet (NUV) and vacuum ultraviolet (VUV) irradiation test of Kapton/Al second surface mirror film was conducted using laser-induced AO simulation facility; the mass, solar absorptance, surface structure and composition were investigated. The results indicate that the mass of Kapton/Al film is decreased with increasing irradiation time, but the solar absorptance displays entirely different trend, which is increased with increasing irradiation time. After irradiation, the quantity of the main functional groups in Kapton/Al film surface presents downtrend basically. The breakage of C-C and C-N bonds and new chemical bond creation in Kapton/Al film surface are considered mechanisms of the degradation, and gas molecule volatilization leads to the mass loss of Kapton/Al film.
Atomic oxygen (AO), near ultraviolet (NUV) and vacuum ultraviolet (VUV) irradiation test of Kapton/Al second surface mirror film was conducted using laser-induced AO simulation facility; the mass, solar absorptance, surface structure and composition were investigated. The results indicate that the mass of Kapton/Al film is decreased with increasing irradiation time, but the solar absorptance displays entirely different trend, which is increased with increasing irradiation time. After irradiation, the quantity of the main functional groups in Kapton/Al film surface presents downtrend basically. The breakage of C-C and C-N bonds and new chemical bond creation in Kapton/Al film surface are considered mechanisms of the degradation, and gas molecule volatilization leads to the mass loss of Kapton/Al film.
2015,
27: 124007.
doi: 10.11884/HPLPB201527.124007
Abstract:
When the age of a Cf source exceeds 20 years, the relative contribution of Cf-250 and Cm-248 isotopes will increase gradually. Then the total neutron emission rate will not follow the simple index law determined by Cf-252. Based on the laws of radioactive decay and spontaneous fission for every isotope in Cf source, we put forward a method of determining isotope components (Cf-252 and Cf-250) of the sealed Cf source to rapidly estimate the total neutron emission rate of a Cf source over 20 years. The neutron emission of a Cf source about 30 years old was measured relatively by a long counter at one point. Then isotope components of the sealed Cf source were determined. The numbers of Cf-252 nuclei and Cf-250 nuclei at the beginning time of the source were 4.4521016 and 7.7461015. The relations between the total neutron emission rate and the age of the Cf source is calculated based on its components. The calculated results are in accordance with the measured results, and the relative difference between calculation and experiment results is less than 0.3%. Furthermore, the relative contribution of each isotopes, including Cf-252, Cf-250 and Cm-248, to the total neutron emission rate is analyzed. The result shows that the relative contribution of Cf-252 is reduced to 67.65%, while those of Cf-250 and Cm-248 are increased to 29.32% and 2.94% respectively when the age of the Cf source has reached 30 years.
When the age of a Cf source exceeds 20 years, the relative contribution of Cf-250 and Cm-248 isotopes will increase gradually. Then the total neutron emission rate will not follow the simple index law determined by Cf-252. Based on the laws of radioactive decay and spontaneous fission for every isotope in Cf source, we put forward a method of determining isotope components (Cf-252 and Cf-250) of the sealed Cf source to rapidly estimate the total neutron emission rate of a Cf source over 20 years. The neutron emission of a Cf source about 30 years old was measured relatively by a long counter at one point. Then isotope components of the sealed Cf source were determined. The numbers of Cf-252 nuclei and Cf-250 nuclei at the beginning time of the source were 4.4521016 and 7.7461015. The relations between the total neutron emission rate and the age of the Cf source is calculated based on its components. The calculated results are in accordance with the measured results, and the relative difference between calculation and experiment results is less than 0.3%. Furthermore, the relative contribution of each isotopes, including Cf-252, Cf-250 and Cm-248, to the total neutron emission rate is analyzed. The result shows that the relative contribution of Cf-252 is reduced to 67.65%, while those of Cf-250 and Cm-248 are increased to 29.32% and 2.94% respectively when the age of the Cf source has reached 30 years.
2015,
27: 124008.
doi: 10.11884/HPLPB201527.124008
Abstract:
The use of magnetic control method could improve the scramjet propulsion performance. The Maxwell equations and N-S equations were combined and these equations were simplified. The flow field numerical simulation model of distribution was established to calculate the MHD scramjet magnetic inlet flow field. The flow field characteristic, electric potential, current and power extraction were studied under certain conditions. MHD generator could reduce the Mach number flow speed and total enthalpy at the exit of the pipe. However, the temperature would increase at the exit of the pipe. The electric potential remained constant at the electrode and the electric potential was higher on the insulation wall and the electric field at the electrode endpoint changed periodically. The current along y direction near the plate electrode was very high and almost zero on the insulation board. The current mainly flowed from the positive electrode to the negative electrode and slightly decreased along the x direction. The maximum current along y direction appeared on the insulation wall and the current along z direction was almost zero on the insulation wall. The z direction current appears at the corner of the pipe and the z direction current on the insulation wall was almost zero. The normal component of the current on the insulation wall was almost zero.
The use of magnetic control method could improve the scramjet propulsion performance. The Maxwell equations and N-S equations were combined and these equations were simplified. The flow field numerical simulation model of distribution was established to calculate the MHD scramjet magnetic inlet flow field. The flow field characteristic, electric potential, current and power extraction were studied under certain conditions. MHD generator could reduce the Mach number flow speed and total enthalpy at the exit of the pipe. However, the temperature would increase at the exit of the pipe. The electric potential remained constant at the electrode and the electric potential was higher on the insulation wall and the electric field at the electrode endpoint changed periodically. The current along y direction near the plate electrode was very high and almost zero on the insulation board. The current mainly flowed from the positive electrode to the negative electrode and slightly decreased along the x direction. The maximum current along y direction appeared on the insulation wall and the current along z direction was almost zero on the insulation wall. The z direction current appears at the corner of the pipe and the z direction current on the insulation wall was almost zero. The normal component of the current on the insulation wall was almost zero.
2015,
27: 124101.
doi: 10.11884/HPLPB201527.124101
Abstract:
In design of the bulk acoustic wave (BAW) duplexer, the resonance area of each thin film bulk acoustic wave resonator (FBAR) in Tx or Rx filters affects its performance of insertion loss and out of band rejection. However, these two properties of the filter in design often need to compromise, which brings difficulty for calculating the resonance area of each FBAR in filter. In order to solve this problem, a new parametric design method of Tx or Rx filter is proposed. The circuit model of filter was established by the foundation of FBAR Mason model in ADS software. The resonance area value of series FBAR and the ratio of resonance area value of parallel FBAR to series FBAR were made into two types of optimization parameters reasonably. According to the given insertion loss and out of band rejection of filter as the optimization objective, the optimized values were obtained by the algorithm based on gradient in ADS software. To design BAW duplexer used in LTE band 7 for example, simulation results show that the insertion loss of the Tx and Rx filter using this method is less than 2 dB and the rejection in passband of each other filter is greater than 40 dB, which meets the performance indicators of Tx and Rx filters and verifies the feasibility and ease of use of the method.
In design of the bulk acoustic wave (BAW) duplexer, the resonance area of each thin film bulk acoustic wave resonator (FBAR) in Tx or Rx filters affects its performance of insertion loss and out of band rejection. However, these two properties of the filter in design often need to compromise, which brings difficulty for calculating the resonance area of each FBAR in filter. In order to solve this problem, a new parametric design method of Tx or Rx filter is proposed. The circuit model of filter was established by the foundation of FBAR Mason model in ADS software. The resonance area value of series FBAR and the ratio of resonance area value of parallel FBAR to series FBAR were made into two types of optimization parameters reasonably. According to the given insertion loss and out of band rejection of filter as the optimization objective, the optimized values were obtained by the algorithm based on gradient in ADS software. To design BAW duplexer used in LTE band 7 for example, simulation results show that the insertion loss of the Tx and Rx filter using this method is less than 2 dB and the rejection in passband of each other filter is greater than 40 dB, which meets the performance indicators of Tx and Rx filters and verifies the feasibility and ease of use of the method.
2015,
27: 124102.
doi: 10.11884/HPLPB201527.124102
Abstract:
To reach the requirement of optical elements in the aerospace infrared remote sensor being highly transmissive and thermally diffusive, this paper proposed a reticular microstructure with the wavelength selection characteristic. The characteristic parameters of the reticular microstructure were designed based on the equivalent medium theory and mathematical modeling theory, and Matlab was used to simulate the spectral radiant characteristics on the reticular microstructure surface. The microstructure was fabricated by plasma etching, and its surface topography was analyzed by scanning electron microscope (SEM). The results reveal that the reactive gas flow rate, RF power and the chamber pressure are critical for the morphology of the microstructure and the steepness of sidewall. By optimizing and analyzing the parameters, the experimental results illustrate that the transmission diffraction efficiency of the microstructure achieved over 91.5% at an operating wavelength of 10.6 m under optimized conditions. This can basically fulfill the requirement of reticular microstructure for aerospace infrared remote sensor utilization.
To reach the requirement of optical elements in the aerospace infrared remote sensor being highly transmissive and thermally diffusive, this paper proposed a reticular microstructure with the wavelength selection characteristic. The characteristic parameters of the reticular microstructure were designed based on the equivalent medium theory and mathematical modeling theory, and Matlab was used to simulate the spectral radiant characteristics on the reticular microstructure surface. The microstructure was fabricated by plasma etching, and its surface topography was analyzed by scanning electron microscope (SEM). The results reveal that the reactive gas flow rate, RF power and the chamber pressure are critical for the morphology of the microstructure and the steepness of sidewall. By optimizing and analyzing the parameters, the experimental results illustrate that the transmission diffraction efficiency of the microstructure achieved over 91.5% at an operating wavelength of 10.6 m under optimized conditions. This can basically fulfill the requirement of reticular microstructure for aerospace infrared remote sensor utilization.
2015,
27: 125001.
doi: 10.11884/HPLPB201527.125001
Abstract:
Magnetically driven flyer plate experiments, shot 151 with a 370 m thick aluminum flyer plate and shot 164 with a 330 m thick aluminum flyer plate, carried out in the large current pulse device PTS are simulated and analyzed with the two-dimensional magneto-hydrodynamics code MDSC2. Numerical simulation shows that the material near the free surface of the flyer plate melts or evaporates due to ablation, with the remaining part between the free surface and the loading surface staying solid. This finding tells us that the velocity measured by VISAR in the experiments may not be that of the free surface as expectation but be the one of the liquid-solid interface beyond the free surface, since the laser of the VISAR will penetrate through the melt or evaporated part and reflect back at the liquid-solid interface. This idea is confirmed by the coincidence of the simulated velocity of the liquid-solid interface and the measured one by the VISAR.
Magnetically driven flyer plate experiments, shot 151 with a 370 m thick aluminum flyer plate and shot 164 with a 330 m thick aluminum flyer plate, carried out in the large current pulse device PTS are simulated and analyzed with the two-dimensional magneto-hydrodynamics code MDSC2. Numerical simulation shows that the material near the free surface of the flyer plate melts or evaporates due to ablation, with the remaining part between the free surface and the loading surface staying solid. This finding tells us that the velocity measured by VISAR in the experiments may not be that of the free surface as expectation but be the one of the liquid-solid interface beyond the free surface, since the laser of the VISAR will penetrate through the melt or evaporated part and reflect back at the liquid-solid interface. This idea is confirmed by the coincidence of the simulated velocity of the liquid-solid interface and the measured one by the VISAR.
2015,
27: 125002.
doi: 10.11884/HPLPB201527.125002
Abstract:
Normally, very limited data can be collected during the electromagnetic effect experiments. So it is hard to fit effect threshold curve based on classical mathematical statistics. This paper employs Bayesian mathematical statistics to fit the data of pipeline Supervisory Control and Data Acquisition systems Master Control Set client effect experiment. We choose Weibull model and normal model as the hypothesis models, and calculate the model parameters prior distribution, likelihood function and posteriori distribution orderly. After tests of goodness of fit, we find that the Weibull model with shape parameter equals 8.87 and scale parameter equals 21.11 is more suitable for effects evaluation based on BIC calculated result, providing a more reliable threshold probability distribution for effect assessment of electromagnetic pulse at equipment level.
Normally, very limited data can be collected during the electromagnetic effect experiments. So it is hard to fit effect threshold curve based on classical mathematical statistics. This paper employs Bayesian mathematical statistics to fit the data of pipeline Supervisory Control and Data Acquisition systems Master Control Set client effect experiment. We choose Weibull model and normal model as the hypothesis models, and calculate the model parameters prior distribution, likelihood function and posteriori distribution orderly. After tests of goodness of fit, we find that the Weibull model with shape parameter equals 8.87 and scale parameter equals 21.11 is more suitable for effects evaluation based on BIC calculated result, providing a more reliable threshold probability distribution for effect assessment of electromagnetic pulse at equipment level.
2015,
27: 125003.
doi: 10.11884/HPLPB201527.125003
Abstract:
4H-SiC photoconductive switches with a lateral geometry are fabricated. Phosphate ion implantation is adopted to decrease the resistance. The results show that phosphate ion implantation can effectively reduce the resistance nearing the electrode and the minimum unit of the electrode gap on-state resistance is 3.17 / mm. This experiment shows the bias voltage and optical pulse energy how to effect the on-state resistance. The power of the device is more than 2.0 MW when the bias voltage is 10 kV and the energy of light is 30.5 mJ. The characteristics of the switch output are stable, low jitter and high power. This is of importance to the application of silicon carbide photoconductive switch.
4H-SiC photoconductive switches with a lateral geometry are fabricated. Phosphate ion implantation is adopted to decrease the resistance. The results show that phosphate ion implantation can effectively reduce the resistance nearing the electrode and the minimum unit of the electrode gap on-state resistance is 3.17 / mm. This experiment shows the bias voltage and optical pulse energy how to effect the on-state resistance. The power of the device is more than 2.0 MW when the bias voltage is 10 kV and the energy of light is 30.5 mJ. The characteristics of the switch output are stable, low jitter and high power. This is of importance to the application of silicon carbide photoconductive switch.
2015,
27: 125004.
doi: 10.11884/HPLPB201527.125004
Abstract:
An uneven dual-output pulse generator was presented in this paper, whose pulse forming line consisted of three coaxial cylinders and a build-in Tesla transform. Such a generator possessed two uneven output ports with high and low wave impedance each. The polarity of the dual-output pulses was opposite, and the pulse amplitude of the high-impedance output port was higher relatively. A pulse splitting-delaying device was connected with the low-impedance output port to realize accordant impedance at output terminals, and multiplex pulses with a low and even amplitude were obtained. One design example of the UWS (ultra-wide spectrum) pulse-series generator was given. After being delayed transmission multiplex output pulses of such a generator could form combined pulse which composed of first high-amplitude pulse and following even-amplitude pulses.
An uneven dual-output pulse generator was presented in this paper, whose pulse forming line consisted of three coaxial cylinders and a build-in Tesla transform. Such a generator possessed two uneven output ports with high and low wave impedance each. The polarity of the dual-output pulses was opposite, and the pulse amplitude of the high-impedance output port was higher relatively. A pulse splitting-delaying device was connected with the low-impedance output port to realize accordant impedance at output terminals, and multiplex pulses with a low and even amplitude were obtained. One design example of the UWS (ultra-wide spectrum) pulse-series generator was given. After being delayed transmission multiplex output pulses of such a generator could form combined pulse which composed of first high-amplitude pulse and following even-amplitude pulses.
2015,
27: 125005.
doi: 10.11884/HPLPB201527.125005
Abstract:
The effect of the pulse width change is studied on the membrane voltage and energy of cell membranes and organelles membrane under the high voltage pulse electric field. The sterilization effect of saccharomyces cerevisiae (CICC31180) changes with the quantity of the 13 s, 200 ns or 2 ns pulses. The results showed that with the increase of the quantity of pulses, the sterilization effect was enhanced. The yeast concentration decreased by 4.3 orders of magnitude after 50, 13 s width, 14 kV pulses treatment while by 2.8 orders of magnitude after 500, 13 ns width 200 kV pulses treatment, by 2.6 orders of magnitude after 500, 13 ns width 200 kV pulses treatment. The survival rate logarithmic relation with the pulse number was not linear. The survival rate logarithmic decreased slowly when the pulse number increased to a higher value. Under the same survival rate logarithmic decrease, the loss of energy in coaxial electrode was lower in 2 ns pulses than 13 s or 200 ns pulses.
The effect of the pulse width change is studied on the membrane voltage and energy of cell membranes and organelles membrane under the high voltage pulse electric field. The sterilization effect of saccharomyces cerevisiae (CICC31180) changes with the quantity of the 13 s, 200 ns or 2 ns pulses. The results showed that with the increase of the quantity of pulses, the sterilization effect was enhanced. The yeast concentration decreased by 4.3 orders of magnitude after 50, 13 s width, 14 kV pulses treatment while by 2.8 orders of magnitude after 500, 13 ns width 200 kV pulses treatment, by 2.6 orders of magnitude after 500, 13 ns width 200 kV pulses treatment. The survival rate logarithmic relation with the pulse number was not linear. The survival rate logarithmic decreased slowly when the pulse number increased to a higher value. Under the same survival rate logarithmic decrease, the loss of energy in coaxial electrode was lower in 2 ns pulses than 13 s or 200 ns pulses.
2015,
27: 125006.
doi: 10.11884/HPLPB201527.125006
Abstract:
In order to measure the electric field of electromagnetic pulse with nanosecond rise time, a kind of broad-band electric field of electromagnetic pulse measurement system based on FPGA is proposed. Monopole antenna is used to receive electrical signal, high-speed AD converter is used to sample voltage signal, and the sampled data can be received and saved into DDR2 and FLASH Memory by FPGA. The key technologies of signal conditioning, trigger mode, FPGA control and anti-interference are emphatically introduced. The performance and function of the electric field probe are tested by experiment. The sampled signals by electric field probe and oscilloscope are processed and compared by software. Research results show that the electric field of electromagnetic pulse measurement system has the characteristics of good linearity, small size, high noise immunity, and it can be used to measure the electric field of electromagnetic pulse with more than 2.5 ns rise time and 0-50 kV/m electric field intensity.
In order to measure the electric field of electromagnetic pulse with nanosecond rise time, a kind of broad-band electric field of electromagnetic pulse measurement system based on FPGA is proposed. Monopole antenna is used to receive electrical signal, high-speed AD converter is used to sample voltage signal, and the sampled data can be received and saved into DDR2 and FLASH Memory by FPGA. The key technologies of signal conditioning, trigger mode, FPGA control and anti-interference are emphatically introduced. The performance and function of the electric field probe are tested by experiment. The sampled signals by electric field probe and oscilloscope are processed and compared by software. Research results show that the electric field of electromagnetic pulse measurement system has the characteristics of good linearity, small size, high noise immunity, and it can be used to measure the electric field of electromagnetic pulse with more than 2.5 ns rise time and 0-50 kV/m electric field intensity.
2015,
27: 126001.
doi: 10.11884/HPLPB201527.126001
Abstract:
High-energy neutral beam injection(NBI) is one of the four Tokamak auxiliary heating methods(The four methods are the neutral beam injection, lower hybrid, ion cyclotron waves paragraph, and the section electron cyclotron waves). Due to the highest heating efficiency, and the clearly physical mechanism, NBI is regarded as the most effective heating method by international fusion community. In order to explore shine through of EAST（Experimental Advanced Superconducting Tokamak）-NBI, specific hardware circuit block diagram and experimental scheme are designed based on the theoretical analysis of the principle of shine through, and the correctness of the theoretical deduction is verified by experiments. The method of quantitative calibration of the thermocouple in the center point of the ion source beam spot is the standard for the calculation of the shine-through. The value of shine-through is calculated by the ratio of the armor tile thermocouple unit energy of temperature rise to that of calibrated one. The experimental results show that, in a certain range, the shine through increases linearly with the increase of the injection beam energy, and decreases exponentially with the increase of the plasma density.
High-energy neutral beam injection(NBI) is one of the four Tokamak auxiliary heating methods(The four methods are the neutral beam injection, lower hybrid, ion cyclotron waves paragraph, and the section electron cyclotron waves). Due to the highest heating efficiency, and the clearly physical mechanism, NBI is regarded as the most effective heating method by international fusion community. In order to explore shine through of EAST（Experimental Advanced Superconducting Tokamak）-NBI, specific hardware circuit block diagram and experimental scheme are designed based on the theoretical analysis of the principle of shine through, and the correctness of the theoretical deduction is verified by experiments. The method of quantitative calibration of the thermocouple in the center point of the ion source beam spot is the standard for the calculation of the shine-through. The value of shine-through is calculated by the ratio of the armor tile thermocouple unit energy of temperature rise to that of calibrated one. The experimental results show that, in a certain range, the shine through increases linearly with the increase of the injection beam energy, and decreases exponentially with the increase of the plasma density.
2015,
27: 126002.
doi: 10.11884/HPLPB201527.126002
Abstract:
The containment external heat environment of a large nuclear reactor passive containment cooling system (PCS) was studied. A natural convection heat transfer model of the containment narrow space was established, the flow field was simulated based on Navier-Stokes (N-S) equations, also the influence of the outlet height on passive containment cooling system cooling performance was studied. The results show that: when the inlet air is under 308.15 K, 1atm conditions, the area weighted average temperature of criterion type containment outlet is 330.33 K, the cooling air mass flow is 275.85 kg/s, the took away heat is 6160 kW; with the increase of outlet height, the mass flow and heat transfer of containment outlet are increasing, but the slope of the changing curve is decreasing, and finally leveled off, while the cooling air temperature efficiency which is a measure of cooling capacity decreases linearly, air resistance increases linearly, accordingly, sthere is an optimal design.
The containment external heat environment of a large nuclear reactor passive containment cooling system (PCS) was studied. A natural convection heat transfer model of the containment narrow space was established, the flow field was simulated based on Navier-Stokes (N-S) equations, also the influence of the outlet height on passive containment cooling system cooling performance was studied. The results show that: when the inlet air is under 308.15 K, 1atm conditions, the area weighted average temperature of criterion type containment outlet is 330.33 K, the cooling air mass flow is 275.85 kg/s, the took away heat is 6160 kW; with the increase of outlet height, the mass flow and heat transfer of containment outlet are increasing, but the slope of the changing curve is decreasing, and finally leveled off, while the cooling air temperature efficiency which is a measure of cooling capacity decreases linearly, air resistance increases linearly, accordingly, sthere is an optimal design.
2015,
27: 124103.
doi: 10.11884/HPLPB201527.124103
Abstract:
The single-walled carbon nanotubes-Al (SWCNTs-Al) thin film is successfully fabricated by combining the electrophoretic deposition and laser nanowelding technology at room temperature. First, the single-walled carbon nanotubes are deposited onto an Al substrate by electrophoretic deposition, and then a reliable connection is constructed between them by pico-second pulsed laser. The field emission performance test results of the SWCNTs-Al thin film show that the turn-on voltage decreases from 5.1 V/m to 2.1 V/m, and the emission current increases significantly and becomes more stable. This is mainly due to the reduction of contact resistance in welding area and easily moving electrons for field emission after laser nanowelding. Based on the surface topography and the field emission property testing results of the SWCNTs-Al thin film, the optimal laser nanowelding parameters are determined, which are important for the development of nanowelding technology and the large-scale production of nano-devices with ultra-high performance.
The single-walled carbon nanotubes-Al (SWCNTs-Al) thin film is successfully fabricated by combining the electrophoretic deposition and laser nanowelding technology at room temperature. First, the single-walled carbon nanotubes are deposited onto an Al substrate by electrophoretic deposition, and then a reliable connection is constructed between them by pico-second pulsed laser. The field emission performance test results of the SWCNTs-Al thin film show that the turn-on voltage decreases from 5.1 V/m to 2.1 V/m, and the emission current increases significantly and becomes more stable. This is mainly due to the reduction of contact resistance in welding area and easily moving electrons for field emission after laser nanowelding. Based on the surface topography and the field emission property testing results of the SWCNTs-Al thin film, the optimal laser nanowelding parameters are determined, which are important for the development of nanowelding technology and the large-scale production of nano-devices with ultra-high performance.
