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RSS2015 Vol. 27, No. 09
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2015,
27: 090201.
doi: 10.11884/HPLPB201527.090201
Abstract:
Abilities against radiation effects denote the sensitivity of systems to radiation damage, which can be achieved by design and manufacture, and represent the development level of radiation-hardening by design. In this paper, based on the QMU method, a flow of quantitative method for designing systems with radiation damage considered is raised. Firstly, the overall design of systems should be optimized, by dividing a system into different sub-systems, parts, and with different failure modes considered. Secondly, the radiation environment and the uncertainties have to be quantitatively verified. Then the corresponding radiation damage and uncertainties of the devices and sub-systems need to be evaluated, to make sure that the system operates safely. In the end, the overall ability of the system against radiation damage is predicted and verified.
Abilities against radiation effects denote the sensitivity of systems to radiation damage, which can be achieved by design and manufacture, and represent the development level of radiation-hardening by design. In this paper, based on the QMU method, a flow of quantitative method for designing systems with radiation damage considered is raised. Firstly, the overall design of systems should be optimized, by dividing a system into different sub-systems, parts, and with different failure modes considered. Secondly, the radiation environment and the uncertainties have to be quantitatively verified. Then the corresponding radiation damage and uncertainties of the devices and sub-systems need to be evaluated, to make sure that the system operates safely. In the end, the overall ability of the system against radiation damage is predicted and verified.
2015,
27: 091001.
doi: 10.11884/HPLPB201527.091001
Abstract:
In order to improve the output energy stability of non-chain discharge-pumped pulsed HF laser, the chemical reaction dynamics of the HF laser and key factors determining the output stability were analyzed. The combination of the generation of fundamental-state HF molecules, the rising temperature of gases and the consumption of C2H6 was responsible for the rapid decrease of output energy. Experiments were performed to verify the analysis, from which some conclusions could be drawn as follows. The output energy decreased by as high as roughly 31% of the starting value without eliminating of reaction products (i.e., the fundamental-state HF molecules), whereas the output energy was relatively much more stable with zeolite molecular sieve to adsorb the fundamental-state HF molecules after 1600 output pulses. The output energy decreasing ratio of the latter was only 10% after 5500 output pulses. In addition, temperature recovering of gain medium to the initial state, as well as the supplement of C2H6 into the cavity, was demonstrated to improve the stability of output energy. Quantitatively, supplement of C2H6 by 25% could improve the output energy by 8%. According to the chemical reaction dynamics and experimental results, the output energy stability is supposed to be improved by mounting the zeolite molecular sieve absorber, gases temperature controller and real-time gain medium supplement unit into the HF laser device.
In order to improve the output energy stability of non-chain discharge-pumped pulsed HF laser, the chemical reaction dynamics of the HF laser and key factors determining the output stability were analyzed. The combination of the generation of fundamental-state HF molecules, the rising temperature of gases and the consumption of C2H6 was responsible for the rapid decrease of output energy. Experiments were performed to verify the analysis, from which some conclusions could be drawn as follows. The output energy decreased by as high as roughly 31% of the starting value without eliminating of reaction products (i.e., the fundamental-state HF molecules), whereas the output energy was relatively much more stable with zeolite molecular sieve to adsorb the fundamental-state HF molecules after 1600 output pulses. The output energy decreasing ratio of the latter was only 10% after 5500 output pulses. In addition, temperature recovering of gain medium to the initial state, as well as the supplement of C2H6 into the cavity, was demonstrated to improve the stability of output energy. Quantitatively, supplement of C2H6 by 25% could improve the output energy by 8%. According to the chemical reaction dynamics and experimental results, the output energy stability is supposed to be improved by mounting the zeolite molecular sieve absorber, gases temperature controller and real-time gain medium supplement unit into the HF laser device.
2015,
27: 091002.
doi: 10.11884/HPLPB201527.091002
Abstract:
In order to minimize the effect of microlens array position error on homogenized spot, the influence of microlens array relative position error on diode laser beams homogenized spot is researched, and a laser diode beam homogenization system based on microlens array is designed. The position errors owning to the variation of six degrees of freedom between the two arrays are classified into distance error, offset error and rotation error, and the effects of the three kinds of position errors on beam homogenization are studied. The homogenization system is tested by a laser diode array consisting of 6 bars, a uniform pumped spot with 90.75% homogeneity is achieved, and the factors influencing the spot homogeneity are analyzed.
In order to minimize the effect of microlens array position error on homogenized spot, the influence of microlens array relative position error on diode laser beams homogenized spot is researched, and a laser diode beam homogenization system based on microlens array is designed. The position errors owning to the variation of six degrees of freedom between the two arrays are classified into distance error, offset error and rotation error, and the effects of the three kinds of position errors on beam homogenization are studied. The homogenization system is tested by a laser diode array consisting of 6 bars, a uniform pumped spot with 90.75% homogeneity is achieved, and the factors influencing the spot homogeneity are analyzed.
2015,
27: 091003.
doi: 10.11884/HPLPB201527.091003
Abstract:
Based on the mass, momentum, and energy conservation principle, a 3-D unsteady conjugate conduction-natural convection model was developed to simulate the laser irradiation effects on liquid tank. By means of equation analysis, the scaling law for this problem was obtained. According to the scaling law, a full-scale prototype and the corresponding reduced-scale model were established and analysed, respectively. It shows that similarity existed between the full-scale prototype and the reduced-scale model. Moreover, an experiment with the small scale model was performed to verify the numerical model. The measurement results are in good agreement with the ones obtained by the numerical simulation.
Based on the mass, momentum, and energy conservation principle, a 3-D unsteady conjugate conduction-natural convection model was developed to simulate the laser irradiation effects on liquid tank. By means of equation analysis, the scaling law for this problem was obtained. According to the scaling law, a full-scale prototype and the corresponding reduced-scale model were established and analysed, respectively. It shows that similarity existed between the full-scale prototype and the reduced-scale model. Moreover, an experiment with the small scale model was performed to verify the numerical model. The measurement results are in good agreement with the ones obtained by the numerical simulation.
2015,
27: 091004.
doi: 10.11884/HPLPB201527.091004
Abstract:
A dim small moving target detection algorithm based on joint spatio-temporal sparse recovery is proposed in this paper. A spatio-temporal over-complete dictionary is firstly trained from infrared image sequence, and it can characterize not only motion information but also morphological feature. In the spatio-temporal over-complete dictionary, the spatio-temporal atom are then classified as target spatio-temporal atoms building target spatio-temporal over-complete dictionary, which describes moving target, and background spatio-temporal atoms constructing background spatio-temporal over-complete dictionary, which embeds background clutter. Infrared image sequence is decomposed on the union of target spatio-temporal over-complete dictionary and background spatio-temporal over-complete dictionary. The residuals after decomposing and reconstruction by the target spatio-temporal over-complete dictionary and background over-complete dictionary differ very distinctly, and they are then adopted to decide the signal is from target or background. Some experiments are conducted and the experimental results show that the residual reconstructed by its homologous spatio-temporal over-complete dictionary is very little, yet the residual recovered by its heterogonous spatio-temporal over-complete dictionary is quite large. This proposed approach could not only improve the sparsity more efficiently, but also enhance the target detection performance more effectively.
A dim small moving target detection algorithm based on joint spatio-temporal sparse recovery is proposed in this paper. A spatio-temporal over-complete dictionary is firstly trained from infrared image sequence, and it can characterize not only motion information but also morphological feature. In the spatio-temporal over-complete dictionary, the spatio-temporal atom are then classified as target spatio-temporal atoms building target spatio-temporal over-complete dictionary, which describes moving target, and background spatio-temporal atoms constructing background spatio-temporal over-complete dictionary, which embeds background clutter. Infrared image sequence is decomposed on the union of target spatio-temporal over-complete dictionary and background spatio-temporal over-complete dictionary. The residuals after decomposing and reconstruction by the target spatio-temporal over-complete dictionary and background over-complete dictionary differ very distinctly, and they are then adopted to decide the signal is from target or background. Some experiments are conducted and the experimental results show that the residual reconstructed by its homologous spatio-temporal over-complete dictionary is very little, yet the residual recovered by its heterogonous spatio-temporal over-complete dictionary is quite large. This proposed approach could not only improve the sparsity more efficiently, but also enhance the target detection performance more effectively.
2015,
27: 091005.
doi: 10.11884/HPLPB201527.091005
Abstract:
A part local contrast measure algorithm is proposed to solve the problem of low efficiency of original local contrast measure, which combines region saliency with original local contrast measure. Instead of finding target in the whole image, the local contrast measure is constrained in saliency region of current image frame in the proposed method. At the first stage, the image entropy and local similarity feature are used to evaluate the saliency of infrared images, which measures the saliency region of a single frame. At the second stage, the local contrast measure is presented in saliency region, which forms the part local contrast map. An adaptive threshold is adopted to segment the target from part local contrast map. Experiments on several real infrared image sequences have validated the ability of the proposed method in improving the signal-to-noise ratio and the detection capability. In particular, the proposed method can reduce false alarm rate, which is an inherent defect of original local contrast method. The high efficiency is also an important strength of the proposed method, which leads to wide application prospect.
A part local contrast measure algorithm is proposed to solve the problem of low efficiency of original local contrast measure, which combines region saliency with original local contrast measure. Instead of finding target in the whole image, the local contrast measure is constrained in saliency region of current image frame in the proposed method. At the first stage, the image entropy and local similarity feature are used to evaluate the saliency of infrared images, which measures the saliency region of a single frame. At the second stage, the local contrast measure is presented in saliency region, which forms the part local contrast map. An adaptive threshold is adopted to segment the target from part local contrast map. Experiments on several real infrared image sequences have validated the ability of the proposed method in improving the signal-to-noise ratio and the detection capability. In particular, the proposed method can reduce false alarm rate, which is an inherent defect of original local contrast method. The high efficiency is also an important strength of the proposed method, which leads to wide application prospect.
2015,
27: 091006.
doi: 10.11884/HPLPB201527.091006
Abstract:
A new variable step size least mean square (VSS-LMS) algorithm based on the characteristics and shortcomings of traditional adaptive LMS algorithm was proposed. Feasibility of the algorithm was conducted by MATLAB simulation. The minimized hardware system of digital signal processing (DSP) and the software flow chart of VSS-LMS algorithm were designed based on the core of TMS320VC5509, and self-adaptive filtering was achieved for the traditional LMS algorithm and new VSS-LMS algorithm in hardware. Comparative analysis results show that the proposed VSS-LMS algorithm has faster convergence speed and smaller steady state error, which has a certain reference significance for the design and optimization of UV communication receiver system.
A new variable step size least mean square (VSS-LMS) algorithm based on the characteristics and shortcomings of traditional adaptive LMS algorithm was proposed. Feasibility of the algorithm was conducted by MATLAB simulation. The minimized hardware system of digital signal processing (DSP) and the software flow chart of VSS-LMS algorithm were designed based on the core of TMS320VC5509, and self-adaptive filtering was achieved for the traditional LMS algorithm and new VSS-LMS algorithm in hardware. Comparative analysis results show that the proposed VSS-LMS algorithm has faster convergence speed and smaller steady state error, which has a certain reference significance for the design and optimization of UV communication receiver system.
2015,
27: 091007.
doi: 10.11884/HPLPB201527.091007
Abstract:
A novel method based on white light frequency domain interferometry to measure the big step height with high resolution is presented. The measuring range is determined by the central wavelength of the light source and the spectral resolution of the spectrometer, and the maximal range is up to millimeter magnitude. In the verification experiments, the 298.57 m step height was successfully measured with this method, the standard deviation of repeated measurements is less than 0.03 m, the maximal root mean square error is 0.94 m and the experimental results agree well with the actual values.
A novel method based on white light frequency domain interferometry to measure the big step height with high resolution is presented. The measuring range is determined by the central wavelength of the light source and the spectral resolution of the spectrometer, and the maximal range is up to millimeter magnitude. In the verification experiments, the 298.57 m step height was successfully measured with this method, the standard deviation of repeated measurements is less than 0.03 m, the maximal root mean square error is 0.94 m and the experimental results agree well with the actual values.
2015,
27: 091008.
doi: 10.11884/HPLPB201527.091008
Abstract:
An adaptive kernel collaborative representation based anomaly detector for hyperspectral imagery was proposed in view of target detection. Although the sparse representation considers the sparsity of weighted vector, the collaborative representation puts more emphasis on each atoms contribution to the linear combination. A comparability weighted regularization matrix and sum-to-one constraint were employed to reinforce the stability and separability. Then, the kernel parameter was adaptively estimated by using local statistics to improve its own local adaption. The proposed AKCRD algorithm was applied to two hyperspectral datasets comparing with other algorithms such as RX, KRX, SVDD, CRD and KCRD. The simulation results show that the proposed algorithm has better detection performance.
An adaptive kernel collaborative representation based anomaly detector for hyperspectral imagery was proposed in view of target detection. Although the sparse representation considers the sparsity of weighted vector, the collaborative representation puts more emphasis on each atoms contribution to the linear combination. A comparability weighted regularization matrix and sum-to-one constraint were employed to reinforce the stability and separability. Then, the kernel parameter was adaptively estimated by using local statistics to improve its own local adaption. The proposed AKCRD algorithm was applied to two hyperspectral datasets comparing with other algorithms such as RX, KRX, SVDD, CRD and KCRD. The simulation results show that the proposed algorithm has better detection performance.
2015,
27: 091009.
doi: 10.11884/HPLPB201527.091009
Abstract:
For the focusing demand of optical platform applied in photoelectric tracking control system, such as theodolite and quantum communication telescope, a low-cost, small-sized and high-precision optical focusing control system on the basis of the guarantee performance and reliability was designed. With ARM and FPGA as the processing cores, PID optical control platform realized focusing control, according to the image-forming principle. We analyzed how to improve focusing accuracy of the optical platform and utilized the buffer operational amplifier extending the signal method to improve focusing control feedback deviation signal precision. Three kinds of feedback signal compensation methods were put forward and their comparison and analysis were done as well. An equal median compensation method was chosen to compensate the potentiometer feedback signal. This method simplified the hardware and software design without affecting the focusing time, improved the focusing accuracy and was with features of low-power consumption, easy implementation, high focusing control precision, low cost and small size. The subjective analysis was done to an image collected from the focusing experiment. The objective criterion was used to confirm the analysis. And the validity of the design was verified. This design was applied to a photoelectric tracking and detecting product, whose full focusing time was about 3 seconds at 1 m-leveled precision. The design was with fast response as well as stable and reliable performance.
For the focusing demand of optical platform applied in photoelectric tracking control system, such as theodolite and quantum communication telescope, a low-cost, small-sized and high-precision optical focusing control system on the basis of the guarantee performance and reliability was designed. With ARM and FPGA as the processing cores, PID optical control platform realized focusing control, according to the image-forming principle. We analyzed how to improve focusing accuracy of the optical platform and utilized the buffer operational amplifier extending the signal method to improve focusing control feedback deviation signal precision. Three kinds of feedback signal compensation methods were put forward and their comparison and analysis were done as well. An equal median compensation method was chosen to compensate the potentiometer feedback signal. This method simplified the hardware and software design without affecting the focusing time, improved the focusing accuracy and was with features of low-power consumption, easy implementation, high focusing control precision, low cost and small size. The subjective analysis was done to an image collected from the focusing experiment. The objective criterion was used to confirm the analysis. And the validity of the design was verified. This design was applied to a photoelectric tracking and detecting product, whose full focusing time was about 3 seconds at 1 m-leveled precision. The design was with fast response as well as stable and reliable performance.
2015,
27: 091010.
doi: 10.11884/HPLPB201527.091010
Abstract:
The optical system is a key factor for a wind lidar system miniaturization, and the quality of the optical design directly affects the whole performance of the lidar system. A system configuration for all fiber non scanning Doppler wind lidar is presented, and its working principle is briefly introduced. The optical system simulation and design are given. The system working at 1 064 nm wavelength. Design results show that the relative diameter is 1∶4.28, the whole field of view angle is 2022.5, the total length is 277 mm, the back work distance is 127.28 mm, the effective focal length is 300 mm, the diameter of optical system is 70 mm, and each field of optical fiber coupling efficiency is over 65%. the parameters meet the design requirements.
The optical system is a key factor for a wind lidar system miniaturization, and the quality of the optical design directly affects the whole performance of the lidar system. A system configuration for all fiber non scanning Doppler wind lidar is presented, and its working principle is briefly introduced. The optical system simulation and design are given. The system working at 1 064 nm wavelength. Design results show that the relative diameter is 1∶4.28, the whole field of view angle is 2022.5, the total length is 277 mm, the back work distance is 127.28 mm, the effective focal length is 300 mm, the diameter of optical system is 70 mm, and each field of optical fiber coupling efficiency is over 65%. the parameters meet the design requirements.
2015,
27: 091011.
doi: 10.11884/HPLPB201527.091011
Abstract:
In the annular-combination CO2 laser with a phase-locking structure, the principle of external-injection phase-locking is analyzed briefly. By using the theory of equivalent strip resonator, the mathematical model to analyze the output mode is established. The effect of different mirror distortions on the output mode of annular cavity is studied. The results show that, in order to obtain light field distributions which is the same as the mode of injection beam, the mirror distortions of M1 and M2 should be controlled at less than 0.07 times of the wavelength. Simultaneously, the effect of mirror distortions on the output mode under the different mirror parameters is studied. The results could help us to optimize the parameters design of this annular-combination resonator.
In the annular-combination CO2 laser with a phase-locking structure, the principle of external-injection phase-locking is analyzed briefly. By using the theory of equivalent strip resonator, the mathematical model to analyze the output mode is established. The effect of different mirror distortions on the output mode of annular cavity is studied. The results show that, in order to obtain light field distributions which is the same as the mode of injection beam, the mirror distortions of M1 and M2 should be controlled at less than 0.07 times of the wavelength. Simultaneously, the effect of mirror distortions on the output mode under the different mirror parameters is studied. The results could help us to optimize the parameters design of this annular-combination resonator.
2015,
27: 091012.
doi: 10.11884/HPLPB201527.091012
Abstract:
Since the detection range is one of the core indexes for practical application of near ultraviolet detection system, the study of detection range has great practical significance. This paper expounds the principle of near ultraviolet detection system and builds the near ultraviolet detecting range model based on the signal to noise ratio(SNR) analysis of photoelectric detection system. In addition, it analyzes some effects on detection range in detail, including the radiation characteristics in the near ultraviolet spectrum and atmospheric transmittance. Finally, it gives an example using the existing near ultraviolet detector in lab in studying the detection range based on the established model. The study can provide effective theoretical guidance for the development and deep research in the field of near ultraviolet detection technology.
Since the detection range is one of the core indexes for practical application of near ultraviolet detection system, the study of detection range has great practical significance. This paper expounds the principle of near ultraviolet detection system and builds the near ultraviolet detecting range model based on the signal to noise ratio(SNR) analysis of photoelectric detection system. In addition, it analyzes some effects on detection range in detail, including the radiation characteristics in the near ultraviolet spectrum and atmospheric transmittance. Finally, it gives an example using the existing near ultraviolet detector in lab in studying the detection range based on the established model. The study can provide effective theoretical guidance for the development and deep research in the field of near ultraviolet detection technology.
2015,
27: 091013.
doi: 10.11884/HPLPB201527.091013
Abstract:
In distributed fiber optic sensing system based on stimulated Brillouin scattering optical time domain analysis ,the information in temperature or strain measurements is difficult to identify because of the noise mixed into the probe signal. The accuracy of spectral fitting is very important for the identification of sensor information. For the case of the low SNR sensing system, this paper proposes a fitting method to extract high accuracy Brillouin scattering spectral features, which uses wavelet analysis combining the BP (back propagation) network of Levenberg-Marquardt(LM) algorithm to adjust the connection weights. This method overcomes the shortcoming of BP neural networks easy falling into local minima. Meanwhile, the method ensures the precision of values. Numerical simulations show that the method is suitable for different weight ratios, different spectral line widths, low signal to noise ratio and spectral fitting in large scope. With the SNR of 10 dB, the degrees of fitting obtained are more than 0.96. In addition, experimental results demonstrate that this method is suitable for the extraction of the feature of Brillouin scattering spectrum under the circumstances of multiple pump power extraction, and it has higher precision than traditional BP neural network algorithm.
In distributed fiber optic sensing system based on stimulated Brillouin scattering optical time domain analysis ,the information in temperature or strain measurements is difficult to identify because of the noise mixed into the probe signal. The accuracy of spectral fitting is very important for the identification of sensor information. For the case of the low SNR sensing system, this paper proposes a fitting method to extract high accuracy Brillouin scattering spectral features, which uses wavelet analysis combining the BP (back propagation) network of Levenberg-Marquardt(LM) algorithm to adjust the connection weights. This method overcomes the shortcoming of BP neural networks easy falling into local minima. Meanwhile, the method ensures the precision of values. Numerical simulations show that the method is suitable for different weight ratios, different spectral line widths, low signal to noise ratio and spectral fitting in large scope. With the SNR of 10 dB, the degrees of fitting obtained are more than 0.96. In addition, experimental results demonstrate that this method is suitable for the extraction of the feature of Brillouin scattering spectrum under the circumstances of multiple pump power extraction, and it has higher precision than traditional BP neural network algorithm.
2015,
27: 092001.
doi: 10.11884/HPLPB201527.092001
Abstract:
The LARED-Integration code is used for the numerical simulation of the indirect-drive Inertial Confined Fusion. In order to meet with the physics analysis on the whole ignition implosion process, a robust grid relaxation algorithm adaptive to the flow variation is developed for the multi-material arbitrary Lagrangian Eulerian method used in the LARED-Integration code. Compared with the experiment phenomena, the shape of the bubble in the RM instability numerical results is considerable，and the relaxation factor used in the grid relaxation algorithm shows the variation of the density variable. The 2-D implosion process of the multi-layer ignition capsule driven by radiation source is simulated. The whole physical process can be finished and the numerical results are satisfactory according to the physical analysis.
The LARED-Integration code is used for the numerical simulation of the indirect-drive Inertial Confined Fusion. In order to meet with the physics analysis on the whole ignition implosion process, a robust grid relaxation algorithm adaptive to the flow variation is developed for the multi-material arbitrary Lagrangian Eulerian method used in the LARED-Integration code. Compared with the experiment phenomena, the shape of the bubble in the RM instability numerical results is considerable，and the relaxation factor used in the grid relaxation algorithm shows the variation of the density variable. The 2-D implosion process of the multi-layer ignition capsule driven by radiation source is simulated. The whole physical process can be finished and the numerical results are satisfactory according to the physical analysis.
2015,
27: 092002.
doi: 10.11884/HPLPB201527.092002
Abstract:
The cone-wire target is an important sample target for researching collimation of hot electron current and has a significant function in fast ignition decomposition experiments. A new approach of fabricating seamless and adhesiveless Au cone-wire target with diamond turning is proposed. A micro cutting force model is established for diamond turning cone-wire target. The influences of micro cutting force on Au cone-wire target shaping are investigated with different cutting conditions based on the micro cutting force model. Cutting deformation of Au wires with different diameter are also studied with finite element method and experimental verification technique. Au wire regular deformation pattern under different micro cutting force conditions is obtained. It is shown that micro cutting force exerts a serious effect on fabrication deformation of cone-wire target with an approximated diameter of 10 m and has no significant effect on large diameter cone-wire target fabrication.
The cone-wire target is an important sample target for researching collimation of hot electron current and has a significant function in fast ignition decomposition experiments. A new approach of fabricating seamless and adhesiveless Au cone-wire target with diamond turning is proposed. A micro cutting force model is established for diamond turning cone-wire target. The influences of micro cutting force on Au cone-wire target shaping are investigated with different cutting conditions based on the micro cutting force model. Cutting deformation of Au wires with different diameter are also studied with finite element method and experimental verification technique. Au wire regular deformation pattern under different micro cutting force conditions is obtained. It is shown that micro cutting force exerts a serious effect on fabrication deformation of cone-wire target with an approximated diameter of 10 m and has no significant effect on large diameter cone-wire target fabrication.
2015,
27: 092003.
doi: 10.11884/HPLPB201527.092003
Abstract:
Diamond-like carbon (DLC) films are widely used in infrared region. However, DLC is prone to laser damage, which fetters the films usage in infrared high power laser systems and laser protection systems. The laser-induced damage threshold (LIDT) and damage morphology of DLC films were studied based on ISO11254 in different horizontal fields. Ti electrodes were deposited on the DLC films directly. It was found that the field intensity increased from 0 to 700 V/cm and the LIDT also increased; however, the LIDT was relatively unchanged over this horizontal field. Analysis suggests that the horizontal electric field changes the photo-induced carriers drift velocity in DLC films laser-induced area, then reduces the local heat accumulation, slows down the graphitization process in DLC films, and increases the laser-induced damage threshold of DLC film at last.
Diamond-like carbon (DLC) films are widely used in infrared region. However, DLC is prone to laser damage, which fetters the films usage in infrared high power laser systems and laser protection systems. The laser-induced damage threshold (LIDT) and damage morphology of DLC films were studied based on ISO11254 in different horizontal fields. Ti electrodes were deposited on the DLC films directly. It was found that the field intensity increased from 0 to 700 V/cm and the LIDT also increased; however, the LIDT was relatively unchanged over this horizontal field. Analysis suggests that the horizontal electric field changes the photo-induced carriers drift velocity in DLC films laser-induced area, then reduces the local heat accumulation, slows down the graphitization process in DLC films, and increases the laser-induced damage threshold of DLC film at last.
2015,
27: 092004.
doi: 10.11884/HPLPB201527.092004
Abstract:
Combining the dispersion properties of traditional transmission grating and the focusing properties of Fresnel zone plate, we propose a novel transmission self-focusing grating used in soft X-ray region. According to Fresnel diffraction theory, the gratings diffraction properties are derived theoretically, proving that there is a focal plane perpendicular to the grating plane and light waves with different wavelengths focus on different positions of the focal plane. At the focal plane, the photon energy varies linearly with the focal position, which means its able to achieve linear measurement of photon energy. The broadening pattern of focal spot at and perpendicular to the focal plane are obtained by analytic derivation. According to Kirchhoff diffraction formula, a detailed numerical simulation of diffraction patterns is performed by setting practical parameters, and the corresponding measured spectral range and spectral resolution are discussed in detail.
Combining the dispersion properties of traditional transmission grating and the focusing properties of Fresnel zone plate, we propose a novel transmission self-focusing grating used in soft X-ray region. According to Fresnel diffraction theory, the gratings diffraction properties are derived theoretically, proving that there is a focal plane perpendicular to the grating plane and light waves with different wavelengths focus on different positions of the focal plane. At the focal plane, the photon energy varies linearly with the focal position, which means its able to achieve linear measurement of photon energy. The broadening pattern of focal spot at and perpendicular to the focal plane are obtained by analytic derivation. According to Kirchhoff diffraction formula, a detailed numerical simulation of diffraction patterns is performed by setting practical parameters, and the corresponding measured spectral range and spectral resolution are discussed in detail.
2015,
27: 092005.
doi: 10.11884/HPLPB201527.092005
Abstract:
During the fabrication process of polystyrene (PS) shells by emulsion microencapsulation method, solidification is a critical stage that influences the sphericity and wall thickness uniformity. The diameter and wall thickness of compound droplets prepared by the droplet generator were (85010) m and (25025) m respectively. To study the effects of curing temperature on the sphericity and wall thickness uniformity, the curing temperature was set at 25 ℃, 45 ℃ and 65 ℃. The experimental results show that lower temperature improves the sphericity and wall thickness uniformity due to higher interfacial tension and slower velocity of emulsion solidification. When the curing temperature was 25 ℃, the batch yield of PS shells with difference between the maximum and minimum radii less than 2 m is 90%, and with the maximum deviation of wall thickness less than 2 m is 40%, obviously better than that prepared at 45 ℃ and 65 ℃.
During the fabrication process of polystyrene (PS) shells by emulsion microencapsulation method, solidification is a critical stage that influences the sphericity and wall thickness uniformity. The diameter and wall thickness of compound droplets prepared by the droplet generator were (85010) m and (25025) m respectively. To study the effects of curing temperature on the sphericity and wall thickness uniformity, the curing temperature was set at 25 ℃, 45 ℃ and 65 ℃. The experimental results show that lower temperature improves the sphericity and wall thickness uniformity due to higher interfacial tension and slower velocity of emulsion solidification. When the curing temperature was 25 ℃, the batch yield of PS shells with difference between the maximum and minimum radii less than 2 m is 90%, and with the maximum deviation of wall thickness less than 2 m is 40%, obviously better than that prepared at 45 ℃ and 65 ℃.
2015,
27: 092006.
doi: 10.11884/HPLPB201527.092006
Abstract:
The improvement of the amplifier gain and amplifier efficiency is quite attractive in inertia confined fusion (ICF). As an important component of the amplifier, the flash lamp pumping efficiency directly affects the amplifier efficiency. In this paper, a new structure of flash lamp is designed and constructed, going for a higher pumping efficiency. Comparison between the new and the traditional structures are made, in terms of electrical characteristics, radiation and fluorescence behaviors of Nd:glass. Experimental results indicate that the resistance increases in the new structure, corresponding to a lower current and energy feeding. As a result, the intensities of radiation and fluorescence are improved by 3%～4% and 2%～3% respectively. The mechanisms of the improvement, the evolution of the discharge plasma channel, and the scheme of further optimization for the new structure are discussed.
The improvement of the amplifier gain and amplifier efficiency is quite attractive in inertia confined fusion (ICF). As an important component of the amplifier, the flash lamp pumping efficiency directly affects the amplifier efficiency. In this paper, a new structure of flash lamp is designed and constructed, going for a higher pumping efficiency. Comparison between the new and the traditional structures are made, in terms of electrical characteristics, radiation and fluorescence behaviors of Nd:glass. Experimental results indicate that the resistance increases in the new structure, corresponding to a lower current and energy feeding. As a result, the intensities of radiation and fluorescence are improved by 3%～4% and 2%～3% respectively. The mechanisms of the improvement, the evolution of the discharge plasma channel, and the scheme of further optimization for the new structure are discussed.
2015,
27: 092007.
doi: 10.11884/HPLPB201527.092007
Abstract:
For controlling mid-spatial error in the magnetorheological finishing，experiments were carried out to analyze the relationship between the dwell time and mid-spatial error. Based on the matrix method of dwell time algorithm，the fluctuation of the time matrix along the feed direction of polishing reflects the discontinuity of velocity，which will cause the mid-spatial error. This paper advanced to filter the dwell time and smooth the velocity，which can make the velocity of the adjacent points more close，so the polishing wheel only needs a small acceleration and very little time to complete the entire acceleration，so as to reduce the error caused by the fluctuation of speed. Through computer simulation and experiments，it verificated that to give the dwell time a small disturbance，the PSD curve will diverge， and the dwell time filtered will inhabit the mid-spatial error to some extent.
For controlling mid-spatial error in the magnetorheological finishing，experiments were carried out to analyze the relationship between the dwell time and mid-spatial error. Based on the matrix method of dwell time algorithm，the fluctuation of the time matrix along the feed direction of polishing reflects the discontinuity of velocity，which will cause the mid-spatial error. This paper advanced to filter the dwell time and smooth the velocity，which can make the velocity of the adjacent points more close，so the polishing wheel only needs a small acceleration and very little time to complete the entire acceleration，so as to reduce the error caused by the fluctuation of speed. Through computer simulation and experiments，it verificated that to give the dwell time a small disturbance，the PSD curve will diverge， and the dwell time filtered will inhabit the mid-spatial error to some extent.
2015,
27: 092008.
doi: 10.11884/HPLPB201527.092008
Abstract:
The implosion experiment with double quads on SGⅢ facility was the first time laser indirect-drive implosion experiment, also the first time neutron experiment. The experiments used f1400 mm2100 mm hohlraum with f1000 mm LEH and f500 mm CH target with 1 MPa DD fuel, and the laser was injected the hohlraum by 55. The highest neutron yield was 9.7108, up to now, the highest indirect-drive DD neutron yield in domestic experiment. The experimental results show that the coupling efficiency of the hohlraum approximates 50%; the hohlraum is too long, and the pellet is compressed to a pancake; neutron yield is positively correlated with the laser energy; the Bang Time depends on the thickness of the ablative layer.
The implosion experiment with double quads on SGⅢ facility was the first time laser indirect-drive implosion experiment, also the first time neutron experiment. The experiments used f1400 mm2100 mm hohlraum with f1000 mm LEH and f500 mm CH target with 1 MPa DD fuel, and the laser was injected the hohlraum by 55. The highest neutron yield was 9.7108, up to now, the highest indirect-drive DD neutron yield in domestic experiment. The experimental results show that the coupling efficiency of the hohlraum approximates 50%; the hohlraum is too long, and the pellet is compressed to a pancake; neutron yield is positively correlated with the laser energy; the Bang Time depends on the thickness of the ablative layer.
2015,
27: 092009.
doi: 10.11884/HPLPB201527.092009
Abstract:
To improve the sphericity of large-diameter (about 2 mm) polystyrene (PS) capsules for inertial confinement fusion targets, the effects of the interfacial tension between oil phase and outer water phase, the concentration of oil phase, and the speed of rotation flow field on the sphericity of PS capsules were investigated. The results show that, compared with polyvinyl alcohol (PVA), addition of poly(acrylic acid) (PAA) in the outer water phase leads about 10 times increase of interfacial tension between the oil phase and the outer water phase, resulting in a significant improvement of the sphericity of PS capsules. With the replacement of PVA with PAA, the batch yields of PS capsules with out-of-round (OOR) less than 1 m increased from about 5% to above 50%. However, changing the initial concentrations of the oil phase and the speeds of rotation flow field in a wide range did not affect the sphericity of PS capsules remarkably. Under typical operation conditions, the batch yields of the resulting PS capsules with OOR less than 1 m ranges from 40% to 60%.
To improve the sphericity of large-diameter (about 2 mm) polystyrene (PS) capsules for inertial confinement fusion targets, the effects of the interfacial tension between oil phase and outer water phase, the concentration of oil phase, and the speed of rotation flow field on the sphericity of PS capsules were investigated. The results show that, compared with polyvinyl alcohol (PVA), addition of poly(acrylic acid) (PAA) in the outer water phase leads about 10 times increase of interfacial tension between the oil phase and the outer water phase, resulting in a significant improvement of the sphericity of PS capsules. With the replacement of PVA with PAA, the batch yields of PS capsules with out-of-round (OOR) less than 1 m increased from about 5% to above 50%. However, changing the initial concentrations of the oil phase and the speeds of rotation flow field in a wide range did not affect the sphericity of PS capsules remarkably. Under typical operation conditions, the batch yields of the resulting PS capsules with OOR less than 1 m ranges from 40% to 60%.
2015,
27: 092010.
doi: 10.11884/HPLPB201527.092010
Abstract:
The illumination uniformity on the capsule surface is very important for inertial confinement fusion (ICF) to achieve ignition. In this paper, we analyze the direct drive illumination uniformity provided by Shenguang Ⅲ prototype laser facility which is designed for indirect drive ICF. Highly uniform irradiation is achieved by optimizing the intensity distribution within a laser beam when the power imbalance and pointing errors are taken into account and the results show that the intensity on the capsule becomes more uniform as laser uncertainties decrease. Furthermore, the relation between optimized intensity on the capsule surface and the laser parameters is analyzed and the results show that we can adjust the mean intensity on the capsule surface by changing optimized parameters with length dimension, which is useful for target design. Finally, the optimized results are applied to direct drive fast ignition and it shows that they are applicable when the cone is in the polar region of the capsule and the half cone angle is less than 30.
The illumination uniformity on the capsule surface is very important for inertial confinement fusion (ICF) to achieve ignition. In this paper, we analyze the direct drive illumination uniformity provided by Shenguang Ⅲ prototype laser facility which is designed for indirect drive ICF. Highly uniform irradiation is achieved by optimizing the intensity distribution within a laser beam when the power imbalance and pointing errors are taken into account and the results show that the intensity on the capsule becomes more uniform as laser uncertainties decrease. Furthermore, the relation between optimized intensity on the capsule surface and the laser parameters is analyzed and the results show that we can adjust the mean intensity on the capsule surface by changing optimized parameters with length dimension, which is useful for target design. Finally, the optimized results are applied to direct drive fast ignition and it shows that they are applicable when the cone is in the polar region of the capsule and the half cone angle is less than 30.
2015,
27: 092011.
doi: 10.11884/HPLPB201527.092011
Abstract:
The dynamic prediction method is proposed to calculate the shape of magnetorheological finishing (MRF) removal function. After the establishment of transition mechanism of the shape of removal function, numerical analysis is performed to simplify this mechanism and hence resulting in the rapid prediction method for common MRF process configurations. The result indicates that, for most MRF settings, the variations of length and width change linearly with the variation of immersion depth, exhibiting coefficients of determination higher than 95%. Among the 49 prediction results, the relative errors for predictions of length range from -4.52% to 5.51% and the same figure for width predictions fluctuates from -7.2% to 6.63%.
The dynamic prediction method is proposed to calculate the shape of magnetorheological finishing (MRF) removal function. After the establishment of transition mechanism of the shape of removal function, numerical analysis is performed to simplify this mechanism and hence resulting in the rapid prediction method for common MRF process configurations. The result indicates that, for most MRF settings, the variations of length and width change linearly with the variation of immersion depth, exhibiting coefficients of determination higher than 95%. Among the 49 prediction results, the relative errors for predictions of length range from -4.52% to 5.51% and the same figure for width predictions fluctuates from -7.2% to 6.63%.
2015,
27: 092012.
doi: 10.11884/HPLPB201527.092012
Abstract:
The laser inertial confinement fusion experiment can provide very important data for the research of laser-plasma interaction to detect the spatial and temporal property of the backscatter light. The backscatter diagnostic system we already have dont have temporal resolution for the spatial distribution of backscatter energy. Therefore, based on the near backscatter diagnostic system on SG-Ⅲ prototype laser facility, we proposed and designed a kind of recording method which could detect the temporal process for the spatial distribution of backscatter energy. We verified the feasibility of this method through static experiment, whose result demonstrated that it was possible to record the messages transmitted by one-dimensional to two-dimensional imaging fiber bundles and retrieve these messages to two-dimensional image by data processing.
The laser inertial confinement fusion experiment can provide very important data for the research of laser-plasma interaction to detect the spatial and temporal property of the backscatter light. The backscatter diagnostic system we already have dont have temporal resolution for the spatial distribution of backscatter energy. Therefore, based on the near backscatter diagnostic system on SG-Ⅲ prototype laser facility, we proposed and designed a kind of recording method which could detect the temporal process for the spatial distribution of backscatter energy. We verified the feasibility of this method through static experiment, whose result demonstrated that it was possible to record the messages transmitted by one-dimensional to two-dimensional imaging fiber bundles and retrieve these messages to two-dimensional image by data processing.
2015,
27: 092013.
doi: 10.11884/HPLPB201527.092013
Abstract:
Based on the grate parallel grinding method that applied to large axisymmetric aspheric lenses manufacturing, the grinding parameters influencing the surface roughness are investigated and the distribution of surface roughness on axisymmetric aspherics is researched. Analyzing the interference between grinding wheel and workpiece, the influence mechanism of the interference on waviness error is established and the main effect factors are proposed. The grinding experiment results show that, the values of surface roughness in vertical grinding direction are much larger than that in parallel grinding direction. The values of surface roughness at the center of workpiece are the minimum, while the maximum values appear on the edges. The grinding wheel vibration and interpolation pace are the main affecting factors in parallel and vertical grinding directions, respectively.
Based on the grate parallel grinding method that applied to large axisymmetric aspheric lenses manufacturing, the grinding parameters influencing the surface roughness are investigated and the distribution of surface roughness on axisymmetric aspherics is researched. Analyzing the interference between grinding wheel and workpiece, the influence mechanism of the interference on waviness error is established and the main effect factors are proposed. The grinding experiment results show that, the values of surface roughness in vertical grinding direction are much larger than that in parallel grinding direction. The values of surface roughness at the center of workpiece are the minimum, while the maximum values appear on the edges. The grinding wheel vibration and interpolation pace are the main affecting factors in parallel and vertical grinding directions, respectively.
2015,
27: 092014.
doi: 10.11884/HPLPB201527.092014
Abstract:
The numerical heat barrier is induced when the traditional support operator method is used to solve the diffusion equation with strongly discontinuous coefficients. In this paper, a new support operator method is proposed. In this method, anisotropy conductivity tensors are introduced and defined on grid vertices. The method is applied to two diffusion cases with strongly discontinuous conductivity coefficients. The numerical results agree well with the analytical values, which proves the feasibility of the proposed scheme to solve the diffusion equation with strongly discontinuous coefficients.
The numerical heat barrier is induced when the traditional support operator method is used to solve the diffusion equation with strongly discontinuous coefficients. In this paper, a new support operator method is proposed. In this method, anisotropy conductivity tensors are introduced and defined on grid vertices. The method is applied to two diffusion cases with strongly discontinuous conductivity coefficients. The numerical results agree well with the analytical values, which proves the feasibility of the proposed scheme to solve the diffusion equation with strongly discontinuous coefficients.
2015,
27: 093001.
doi: 10.11884/HPLPB201527.093001
Abstract:
A compact high power microwave circular waveguide TM01-rectangular waveguide TM10 mode converter was designed to realize the high efficiency mode conversion and high power capacity. The simulation result shows that the mode conversion efficiency with a center frequency of 9.7 GHz is more than 99.99%, the return loss is smaller than -40 dB， and the bandwidth with conversion more than 90% exceeds 0.4 GHz. The frequency of the mode converter is tunable for 9.2-10.1 GHz (the efficiency of the mode conversion exceeds 99%) by changing the length of the short circular waveguide. The chamfer angle between the input circular waveguide and coupling circular waveguide can depress the field enhancement and improve the power capacity. The max surface E-field is 100 MV/m with an incident power of 0.7 GW.
A compact high power microwave circular waveguide TM01-rectangular waveguide TM10 mode converter was designed to realize the high efficiency mode conversion and high power capacity. The simulation result shows that the mode conversion efficiency with a center frequency of 9.7 GHz is more than 99.99%, the return loss is smaller than -40 dB， and the bandwidth with conversion more than 90% exceeds 0.4 GHz. The frequency of the mode converter is tunable for 9.2-10.1 GHz (the efficiency of the mode conversion exceeds 99%) by changing the length of the short circular waveguide. The chamfer angle between the input circular waveguide and coupling circular waveguide can depress the field enhancement and improve the power capacity. The max surface E-field is 100 MV/m with an incident power of 0.7 GW.
2015,
27: 093002.
doi: 10.11884/HPLPB201527.093002
Abstract:
In order to improve the soft switching and dynamic response characteristics of the traveling wave tube high voltage converter, the load characteristic of a traveling wave tube is analyzed, and a full bridge LLC resonant converter with a multiplier rectifier is designed. The working principle, modeling and designing methods of the LLC converter are given based on self-sustained phase shift modulation, especially the soft switching in transient condition and the designing guide of control parameter are analyzed. By simulation, the zero voltage switching in the load mutation condition is proved, and the dynamic response characteristic can be improved by changing the control parameter adaptively. By experiment, the typical wave form of LLC converter is further analyzed based on self-sustained phase shift modulation, and the experiment results show that the soft switching can be implemented.
In order to improve the soft switching and dynamic response characteristics of the traveling wave tube high voltage converter, the load characteristic of a traveling wave tube is analyzed, and a full bridge LLC resonant converter with a multiplier rectifier is designed. The working principle, modeling and designing methods of the LLC converter are given based on self-sustained phase shift modulation, especially the soft switching in transient condition and the designing guide of control parameter are analyzed. By simulation, the zero voltage switching in the load mutation condition is proved, and the dynamic response characteristic can be improved by changing the control parameter adaptively. By experiment, the typical wave form of LLC converter is further analyzed based on self-sustained phase shift modulation, and the experiment results show that the soft switching can be implemented.
2015,
27: 093003.
doi: 10.11884/HPLPB201527.093003
Abstract:
A novel T2 mode quadrifilar helix antenna (QHA) fed by a coaxial line is introduced in this article. The inner and outer conductors feed directly across to the four arms of QHA, achieving a phase relation of 0-180-0-180. At the same time, the helix arms are narrow in front half part and wider back, and the absorbing conductor lines are loaded at the end of QHA. Experimental results are in good agreement with simulation results. The QHA achieves a gain of 10.5 dBi, an AR of 1.3 dB, and a smoothness of 2.3 dB in azimuth-plane, providing a technical approach of single antenna to realize omnidirectional circular polarization pattern.
A novel T2 mode quadrifilar helix antenna (QHA) fed by a coaxial line is introduced in this article. The inner and outer conductors feed directly across to the four arms of QHA, achieving a phase relation of 0-180-0-180. At the same time, the helix arms are narrow in front half part and wider back, and the absorbing conductor lines are loaded at the end of QHA. Experimental results are in good agreement with simulation results. The QHA achieves a gain of 10.5 dBi, an AR of 1.3 dB, and a smoothness of 2.3 dB in azimuth-plane, providing a technical approach of single antenna to realize omnidirectional circular polarization pattern.
2015,
27: 093004.
doi: 10.11884/HPLPB201527.093004
Abstract:
The resistance and thickness of distributed-loss circuit of gyrotron traveling wave amplifier are optimized by using the multi-objective genetic algorithm. Maximum gain of 15.9 dB is obtained by optimizing the thickness and resistivity of loss layer as 0.116 mm and 77 882 times the resistivity of copper, respectively. The accuracy is verified by the single-objective genetic algorithm, which makes the amplifier realize effective restraint of gyrotron backward wave oscillation and achieve the maximum gain.
The resistance and thickness of distributed-loss circuit of gyrotron traveling wave amplifier are optimized by using the multi-objective genetic algorithm. Maximum gain of 15.9 dB is obtained by optimizing the thickness and resistivity of loss layer as 0.116 mm and 77 882 times the resistivity of copper, respectively. The accuracy is verified by the single-objective genetic algorithm, which makes the amplifier realize effective restraint of gyrotron backward wave oscillation and achieve the maximum gain.
2015,
27: 093101.
doi: 10.11884/HPLPB201527.093101
Abstract:
This paper introduces the design method of the electron optical system for a 0.22 THz folded waveguide traveling wave tube. As the electron beam current is 10 mA and the beam channel radius of the tube is only about 0.1 mm, the PPM(period permanent magnet) focusing system needs to be carefully designed to transmit this beam current from the electron gun to the collector. A tree-electrode Pierce gun is adopted. The electrodes and PPM are optimized to obtain proper beam waist radius and high transmission efficiency. Maxwell is used to calculate the magnetic flux density on the beam line, and CST is used to simulate the beam transmission. The simulation shows that about 96% of the electron beam reaches the collector and is verified by experiments, which gets about 74% transmission efficiency without magnetic modification. After magnetic modification, the transmission efficiency is improved to 94%, and this tube is able to run in DC mode.
This paper introduces the design method of the electron optical system for a 0.22 THz folded waveguide traveling wave tube. As the electron beam current is 10 mA and the beam channel radius of the tube is only about 0.1 mm, the PPM(period permanent magnet) focusing system needs to be carefully designed to transmit this beam current from the electron gun to the collector. A tree-electrode Pierce gun is adopted. The electrodes and PPM are optimized to obtain proper beam waist radius and high transmission efficiency. Maxwell is used to calculate the magnetic flux density on the beam line, and CST is used to simulate the beam transmission. The simulation shows that about 96% of the electron beam reaches the collector and is verified by experiments, which gets about 74% transmission efficiency without magnetic modification. After magnetic modification, the transmission efficiency is improved to 94%, and this tube is able to run in DC mode.
2015,
27: 093201.
doi: 10.11884/HPLPB201527.093201
Abstract:
Eddy current in the containment of electromagnetic railgun is induced by the pulse current, and it will badly weaken the propulsion of the armature and the efficiency of the electromagnetic railgun (EMG) system. In order to investigate the influence of the containment on the efficiency, a full circuit model in combination with a finite element method was employed. Firstly, the launch efficiency and the eddy-current loss were calculated, and the efficiency of different containment structure and materials were discussed. Results show that, based on a medium caliber electromagnetic railgun with 10 MJ pulse power, its stainless steel containment will reduce the efficiency very seriously, and the eddy-current losses in containment are more than half of muzzle kinetic energy. While laminated structure and high permeability containment can improve the efficiency obviously. Lastly, the influence of the containment on mechanical property of the electromagnetic railgun was analysed. As a result, the decrease of the armature axial force by the containment is the primary cause of efficiency decline, and the decrease of armature radial force can increase the contact resistance between armature and rails, which will reduce the efficiency too; in addition, the decrease of the radial force of barrel components helps to reduce the preload.
Eddy current in the containment of electromagnetic railgun is induced by the pulse current, and it will badly weaken the propulsion of the armature and the efficiency of the electromagnetic railgun (EMG) system. In order to investigate the influence of the containment on the efficiency, a full circuit model in combination with a finite element method was employed. Firstly, the launch efficiency and the eddy-current loss were calculated, and the efficiency of different containment structure and materials were discussed. Results show that, based on a medium caliber electromagnetic railgun with 10 MJ pulse power, its stainless steel containment will reduce the efficiency very seriously, and the eddy-current losses in containment are more than half of muzzle kinetic energy. While laminated structure and high permeability containment can improve the efficiency obviously. Lastly, the influence of the containment on mechanical property of the electromagnetic railgun was analysed. As a result, the decrease of the armature axial force by the containment is the primary cause of efficiency decline, and the decrease of armature radial force can increase the contact resistance between armature and rails, which will reduce the efficiency too; in addition, the decrease of the radial force of barrel components helps to reduce the preload.
2015,
27: 093202.
doi: 10.11884/HPLPB201527.093202
Abstract:
A high power dual-band wideband planar inverted-F antenna (PIFA) is designed. By embedding a L-shape branch-line split in the radiation patch of the planar inverted-F patch antenna, a novel operation of 274 MHz and 680 MHz dual-band is realized. To reduce the size of the structure and add the capacitive load, the resonator is curled under itself. The dual-band PIFA antenna has a percentage bandwidths of 14.6% and 20.1% in the low and high bands with S11 no more than -6 dB. Radiation efficiencies of up to 98% and 99% can be achieved at 274 MHz and 680 MHz, respectively. When the antenna is pressured in a nylon box with 0.2 MPa pressure, its wideband high power capability is more than 200 MW.
A high power dual-band wideband planar inverted-F antenna (PIFA) is designed. By embedding a L-shape branch-line split in the radiation patch of the planar inverted-F patch antenna, a novel operation of 274 MHz and 680 MHz dual-band is realized. To reduce the size of the structure and add the capacitive load, the resonator is curled under itself. The dual-band PIFA antenna has a percentage bandwidths of 14.6% and 20.1% in the low and high bands with S11 no more than -6 dB. Radiation efficiencies of up to 98% and 99% can be achieved at 274 MHz and 680 MHz, respectively. When the antenna is pressured in a nylon box with 0.2 MPa pressure, its wideband high power capability is more than 200 MW.
2015,
27: 094001.
doi: 10.11884/HPLPB201527.094001
Abstract:
Displacement damage effects due to neutron irradiations of CMOS active pixel sensors manufactured by a 0.5 m CMOS N-Well technology are presented through the analysis of the dark signals behavior in pixel arrays. When the fluence of neutron reached the predetermined point, the changes of dark signal, dark signal non-uniformity, saturated output signal and pixel unit output signal were measured off line. Experiment shows that the mean dark signals and the dark signals, non-uniformity increased dramatically with the increasing neutron fluence. Saturation output signal voltage did not degrade obviously even at the highest fluence. It is concluded that a great deal of inhomogeneous defect energy levels occur between pixels irradiated by neutrons, which enhances the dark signals. In addition, individual pixel unit test pins are introduced from the sample chip, and the output signal of the pixel unit is tested under different integration time.
Displacement damage effects due to neutron irradiations of CMOS active pixel sensors manufactured by a 0.5 m CMOS N-Well technology are presented through the analysis of the dark signals behavior in pixel arrays. When the fluence of neutron reached the predetermined point, the changes of dark signal, dark signal non-uniformity, saturated output signal and pixel unit output signal were measured off line. Experiment shows that the mean dark signals and the dark signals, non-uniformity increased dramatically with the increasing neutron fluence. Saturation output signal voltage did not degrade obviously even at the highest fluence. It is concluded that a great deal of inhomogeneous defect energy levels occur between pixels irradiated by neutrons, which enhances the dark signals. In addition, individual pixel unit test pins are introduced from the sample chip, and the output signal of the pixel unit is tested under different integration time.
2015,
27: 094002.
doi: 10.11884/HPLPB201527.094002
Abstract:
The space radiation environments of typical satellite orbits including geostationary orbit, medium earth orbit, and low earth orbit are extracted and calculated using the latest version of Space Radiation 7.0 toolkit. The ion flux-energy spectrums and flux-LET spectrums under different space weather and shielding conditions are analyzed to reveal the characteristics. Taking an SOI SRAM as an example, combining the SEU cross section versus LET relationship obtained by accelerator-based heavy ions testing, the on-orbit soft error rate is predicted. The influence trend and inner mechanism of key parameters on the prediction results are analyzed. Following results are concluded. Four input modes of Space Radiation software result into soft error rates with difference up to about five orders. The on-orbit soft error rate decreases by several orders of magnitude as the thickness of the sensitive volume increases, which is attributed to the fact that the thickness of the sensitive volume is directly related to the average projected area of the sensitive volume and the qualified space ion flux. The prediction result also depends on the funnel length. Finally, the applicability and development of soft error rate prediction model are discussed.
The space radiation environments of typical satellite orbits including geostationary orbit, medium earth orbit, and low earth orbit are extracted and calculated using the latest version of Space Radiation 7.0 toolkit. The ion flux-energy spectrums and flux-LET spectrums under different space weather and shielding conditions are analyzed to reveal the characteristics. Taking an SOI SRAM as an example, combining the SEU cross section versus LET relationship obtained by accelerator-based heavy ions testing, the on-orbit soft error rate is predicted. The influence trend and inner mechanism of key parameters on the prediction results are analyzed. Following results are concluded. Four input modes of Space Radiation software result into soft error rates with difference up to about five orders. The on-orbit soft error rate decreases by several orders of magnitude as the thickness of the sensitive volume increases, which is attributed to the fact that the thickness of the sensitive volume is directly related to the average projected area of the sensitive volume and the qualified space ion flux. The prediction result also depends on the funnel length. Finally, the applicability and development of soft error rate prediction model are discussed.
2015,
27: 095001.
doi: 10.11884/HPLPB201527.095001
Abstract:
The conductor cylinder armature is commonly used in synchronous induction coilgun. A model is developed to calculate the temperature rise of the armature based on the current filament method. The correctness of the model is verified by setting up a 3-stage synchronous induction coilgun test platform. The influence of the armature material and division setting on the temperature rise is analyzed. The result shows that the maximum temperature rise of the armature concentrates in the exterior surface of the tail, and there is a high temperature rise in the front of the armature. When the payload is adjusted to make the quality of the copper armature and the aluminum armature equal, the temperature rise of the former is higher while the influence of the temperature rise on its emission efficiency is lesser than the latter, because the temperature coefficient of resistivity of copper is less than that of aluminum. In addition, the influence of division setting on the calculation results is obvious. From the point of view of influence of the temperature rise on the emission process, the copper armature is more suitable for high-speed emission than aluminum armature.
The conductor cylinder armature is commonly used in synchronous induction coilgun. A model is developed to calculate the temperature rise of the armature based on the current filament method. The correctness of the model is verified by setting up a 3-stage synchronous induction coilgun test platform. The influence of the armature material and division setting on the temperature rise is analyzed. The result shows that the maximum temperature rise of the armature concentrates in the exterior surface of the tail, and there is a high temperature rise in the front of the armature. When the payload is adjusted to make the quality of the copper armature and the aluminum armature equal, the temperature rise of the former is higher while the influence of the temperature rise on its emission efficiency is lesser than the latter, because the temperature coefficient of resistivity of copper is less than that of aluminum. In addition, the influence of division setting on the calculation results is obvious. From the point of view of influence of the temperature rise on the emission process, the copper armature is more suitable for high-speed emission than aluminum armature.
2015,
27: 095002.
doi: 10.11884/HPLPB201527.095002
Abstract:
Insulator vacuum surface flashover is one of the main factors restricting the development of high voltage, high current and the miniaturized pulse power technology applications. In the vacuum environment of PTS, the insulation performance is greatly affected when soft X-rays radiate the insulating material. Therefore, in order to improve the insulation properties of cross-linked polystyrene material in PTS and obtain a deeper understanding of surface flashover mechanism, the radiation effects of soft X-rays on cross-linked polystyrene were studied, influence of different irradiation times on the surface flashover performance was observed. The experimental results show that the surface flashover performance of samples without irradiation is better than the soft X-ray irradiated samples in vacuum, and the surface flashover performance of 14 times irradiated samples is a little better than 2 times irradiated samples in vacuum. At the same time, the mechanism of the soft X-ray radiating insulator surface is used to explain the experimental results very well.
Insulator vacuum surface flashover is one of the main factors restricting the development of high voltage, high current and the miniaturized pulse power technology applications. In the vacuum environment of PTS, the insulation performance is greatly affected when soft X-rays radiate the insulating material. Therefore, in order to improve the insulation properties of cross-linked polystyrene material in PTS and obtain a deeper understanding of surface flashover mechanism, the radiation effects of soft X-rays on cross-linked polystyrene were studied, influence of different irradiation times on the surface flashover performance was observed. The experimental results show that the surface flashover performance of samples without irradiation is better than the soft X-ray irradiated samples in vacuum, and the surface flashover performance of 14 times irradiated samples is a little better than 2 times irradiated samples in vacuum. At the same time, the mechanism of the soft X-ray radiating insulator surface is used to explain the experimental results very well.
2015,
27: 095003.
doi: 10.11884/HPLPB201527.095003
Abstract:
In this paper, utilizing avalanche transistors as switching devices, the methods of designing and optimizing Marx circuit were discussed in detail. Modular improvement was implemented to the Marx circuit and a novel stereo structure of synchronous four-module combining was designed. The theoretical relation of the combining ratio and the combined modules were derived. Using a +300 V DC power and combining four -2.6 kV Marx modules, Gaussian pulses were obtained on a 50 resistive load with -5.0 kV magnitude, 5.3 ns half peak width, 2.0 mJ single-pulse energy. It was realized to stably work under a repetitive frequency of 10 kHz and the time delay jitter was measured less than 100 ps. The four-module combining efficiency was calculated up to 96.2 %. If changing the DC bias voltage between 200 V and 300 V and varying the number of combined modules, the final output magnitude would be regulated from 1.6 kV to 5.0 kV.
In this paper, utilizing avalanche transistors as switching devices, the methods of designing and optimizing Marx circuit were discussed in detail. Modular improvement was implemented to the Marx circuit and a novel stereo structure of synchronous four-module combining was designed. The theoretical relation of the combining ratio and the combined modules were derived. Using a +300 V DC power and combining four -2.6 kV Marx modules, Gaussian pulses were obtained on a 50 resistive load with -5.0 kV magnitude, 5.3 ns half peak width, 2.0 mJ single-pulse energy. It was realized to stably work under a repetitive frequency of 10 kHz and the time delay jitter was measured less than 100 ps. The four-module combining efficiency was calculated up to 96.2 %. If changing the DC bias voltage between 200 V and 300 V and varying the number of combined modules, the final output magnitude would be regulated from 1.6 kV to 5.0 kV.
2015,
27: 095004.
doi: 10.11884/HPLPB201527.095004
Abstract:
To meet the application demand of the field of plasma, a pulse power supply with the functions of manual and automatic and PC controls is developed. The Field Programmable Gate Array (FPGA) is used as the main control chip to generate digital pulse width modulation (DPWM) and relay control signals which are amplified by drive circuit and then drive the full-bridge inverter circuit and the relay. On sampling the real-time temperature and electric current through the temperature sensor DS18B20 and the Hall sensor QBC10PS5, over temperature and short protection circuits are designed. The main circuit, detection circuit, drive circuit, DPWM generation module and the design of pulse transformer are introduced in detail in this paper. Finally, the results of the experiments verify that the pulse power supply meets the technical requirements.
To meet the application demand of the field of plasma, a pulse power supply with the functions of manual and automatic and PC controls is developed. The Field Programmable Gate Array (FPGA) is used as the main control chip to generate digital pulse width modulation (DPWM) and relay control signals which are amplified by drive circuit and then drive the full-bridge inverter circuit and the relay. On sampling the real-time temperature and electric current through the temperature sensor DS18B20 and the Hall sensor QBC10PS5, over temperature and short protection circuits are designed. The main circuit, detection circuit, drive circuit, DPWM generation module and the design of pulse transformer are introduced in detail in this paper. Finally, the results of the experiments verify that the pulse power supply meets the technical requirements.
2015,
27: 095005.
doi: 10.11884/HPLPB201527.095005
Abstract:
The impedance and X-ray radiography states are the main references of rod-pinch diode. In order to study the physical performances of rod-pinch diode, a PIC and photoelectron transport simulation based on Monte Carlo is used to simulate the physics of the 1.2 MV X-ray generator Scorpio rod pinch diode at Institute of Fluid Physics, CAEP. The influence of structure parameters, including anode-cathode radius rate and anode rod stretching out length, on the diode impedance and radiography is given. The simulation results show good uniformity with theory and experiment. A model is proposed to increase the radiation dose rate, which might be applied in the future design of rod-pinch diode.
The impedance and X-ray radiography states are the main references of rod-pinch diode. In order to study the physical performances of rod-pinch diode, a PIC and photoelectron transport simulation based on Monte Carlo is used to simulate the physics of the 1.2 MV X-ray generator Scorpio rod pinch diode at Institute of Fluid Physics, CAEP. The influence of structure parameters, including anode-cathode radius rate and anode rod stretching out length, on the diode impedance and radiography is given. The simulation results show good uniformity with theory and experiment. A model is proposed to increase the radiation dose rate, which might be applied in the future design of rod-pinch diode.
2015,
27: 095006.
doi: 10.11884/HPLPB201527.095006
Abstract:
A high power high voltage constant current capacitor charging power supply is designed and manufactured. It adopts full-bridge topology with series resonant constant current charging technology and the output voltage is adjustable from 0 to 30 kV, the average power can reach 5 kW at the most. The operating process of the circuit is analyzed briefly. The parameters of the power supply are calculated and a designed example is presented. The simulation and experiments are given and the experimental results are in accordance with the calculation request. In experiment, an 18 F capacitor is charged to 30 kV at 0.1 Hz repetition rate by the power supply, the average power is about 1.35 kW. Now the power supply is experimentally investigated for a capacitor charging and it can work steadily.
A high power high voltage constant current capacitor charging power supply is designed and manufactured. It adopts full-bridge topology with series resonant constant current charging technology and the output voltage is adjustable from 0 to 30 kV, the average power can reach 5 kW at the most. The operating process of the circuit is analyzed briefly. The parameters of the power supply are calculated and a designed example is presented. The simulation and experiments are given and the experimental results are in accordance with the calculation request. In experiment, an 18 F capacitor is charged to 30 kV at 0.1 Hz repetition rate by the power supply, the average power is about 1.35 kW. Now the power supply is experimentally investigated for a capacitor charging and it can work steadily.
2015,
27: 095007.
doi: 10.11884/HPLPB201527.095007
Abstract:
To make the shaped charge jet (SCJ) against the passive electromagnetic armor (PEA) more effectively and reduce the dependency about structural design of PEA on different SCJ parameters, a multi-layer plate armor structure is advanced. Through analyzing the equivalent circuits of different multi-layer plates PEA, an outcome can be obtained that the current passing the SCJ and armors increases with the increasing of the armor number when the resistance of the PEA almost equals the SCJ resistance. Moreover, multi-layer plates can reduce the PEA inductance. A mathematical model about the acting time of pulse current on SCJ is established by analyzing the motion law of SCJ among the armors. The results of the numerical calculation indicate that the multi-layer plate armor structure can reduce the valid penetration length of SCJ tip and tail and can increase the acting time of pulse current on SCJ.
To make the shaped charge jet (SCJ) against the passive electromagnetic armor (PEA) more effectively and reduce the dependency about structural design of PEA on different SCJ parameters, a multi-layer plate armor structure is advanced. Through analyzing the equivalent circuits of different multi-layer plates PEA, an outcome can be obtained that the current passing the SCJ and armors increases with the increasing of the armor number when the resistance of the PEA almost equals the SCJ resistance. Moreover, multi-layer plates can reduce the PEA inductance. A mathematical model about the acting time of pulse current on SCJ is established by analyzing the motion law of SCJ among the armors. The results of the numerical calculation indicate that the multi-layer plate armor structure can reduce the valid penetration length of SCJ tip and tail and can increase the acting time of pulse current on SCJ.
2015,
27: 095101.
doi: 10.11884/HPLPB201527.095101
Abstract:
Septum magnet is one of the most important devices for beam injection and extraction in circular particle accelerators. Because of the high-field requirements with thin septa and low stray field, the structure of septum magnet is very complicated. In this paper, the design of septum magnet is shown in detail. Based on the finite element software OPERA, the magnetic field homogeneity and stray field distribution are analyzed. The magnets fabrication is finished after structure optimal design. The measurement results show that the magnetic field homogeneity in good field region is better than the designed value. The stray field could reduce to 2 mT after shielding with high permeability magnetic material, which satisfies the physical requirements.
Septum magnet is one of the most important devices for beam injection and extraction in circular particle accelerators. Because of the high-field requirements with thin septa and low stray field, the structure of septum magnet is very complicated. In this paper, the design of septum magnet is shown in detail. Based on the finite element software OPERA, the magnetic field homogeneity and stray field distribution are analyzed. The magnets fabrication is finished after structure optimal design. The measurement results show that the magnetic field homogeneity in good field region is better than the designed value. The stray field could reduce to 2 mT after shielding with high permeability magnetic material, which satisfies the physical requirements.
2015,
27: 095102.
doi: 10.11884/HPLPB201527.095102
Abstract:
Vibrating wire alignment technique is proposed to be used in the new generation synchrotron radiation light source with ultra-low emmitance. The magnets must be precisely aligned and the alignment tolerance of multipoles on a girder should be better than 30 m. This paper introduces the design of vibrating wire alignment system for High Energy Photon Source-Test Facility. The structure of the specific mechanical system, circuit structure , motion control and data acquisition system are presented in detail.
Vibrating wire alignment technique is proposed to be used in the new generation synchrotron radiation light source with ultra-low emmitance. The magnets must be precisely aligned and the alignment tolerance of multipoles on a girder should be better than 30 m. This paper introduces the design of vibrating wire alignment system for High Energy Photon Source-Test Facility. The structure of the specific mechanical system, circuit structure , motion control and data acquisition system are presented in detail.
2015,
27: 095103.
doi: 10.11884/HPLPB201527.095103
Abstract:
An independently tunable cells(ITC) thermionic cathode radio frequency (RF) gun is used as the injector for a compact FEL terahertz source in CAEP, and it is driven by microwaves through dual feed-in ports. One microwave feed-in port is located at the first cavity to excite the cavity and draw electron out from the cathode surface. Another is located at the last cavity to excite the rest cavities through coupling holes, There is no electromagnetic coupling between the two microwave feed-in ports. With regard to this kind of microwave working, the phase and amplitude of the electric field in the first cavity can be adjustable independently. Therefore the power of the back electron bombardment of the RF gun can be optimized and decreased by means of experimental research. Further more, higher quality beam can be obtained. The updated results about the power test on the thermionic cathode RF gun is introduced in this paper. A beam intensity about 400 mA is measured by beam-current transformer at the exit of the RF gun. And the effect is studied that back electron bombardment could be changed with adjustment of phase and amplitude of the electric field in the first cavity. The test results and phenomenon agree well with the theoretical design ones.
An independently tunable cells(ITC) thermionic cathode radio frequency (RF) gun is used as the injector for a compact FEL terahertz source in CAEP, and it is driven by microwaves through dual feed-in ports. One microwave feed-in port is located at the first cavity to excite the cavity and draw electron out from the cathode surface. Another is located at the last cavity to excite the rest cavities through coupling holes, There is no electromagnetic coupling between the two microwave feed-in ports. With regard to this kind of microwave working, the phase and amplitude of the electric field in the first cavity can be adjustable independently. Therefore the power of the back electron bombardment of the RF gun can be optimized and decreased by means of experimental research. Further more, higher quality beam can be obtained. The updated results about the power test on the thermionic cathode RF gun is introduced in this paper. A beam intensity about 400 mA is measured by beam-current transformer at the exit of the RF gun. And the effect is studied that back electron bombardment could be changed with adjustment of phase and amplitude of the electric field in the first cavity. The test results and phenomenon agree well with the theoretical design ones.
2015,
27: 095104.
doi: 10.11884/HPLPB201527.095104
Abstract:
For a high energy proton radio frequency quadrupole (RFQ) accelerator which requires a RF power source of 324 MHz and 570 kW, 4616V4 tetrode which can output 350 kW is chosen as the main amplifier. Two tetrodes together can provide an RF power of about 700 kW and meet the design requirement. During the construction of the RF source, simulation studies based on Simulink, tetrodes constant current characteristic curve and experimental data are performed for the optimization of the system working conditions, such as anode voltage, input power, working point and output power. Low anode voltage and nearly saturated input power amplifier can effectively increase the operating frequency. The simulation method is verified with the experimental data setup and the conventional 13-point approximate integral method. As a result, the relative error is less than 5%.
For a high energy proton radio frequency quadrupole (RFQ) accelerator which requires a RF power source of 324 MHz and 570 kW, 4616V4 tetrode which can output 350 kW is chosen as the main amplifier. Two tetrodes together can provide an RF power of about 700 kW and meet the design requirement. During the construction of the RF source, simulation studies based on Simulink, tetrodes constant current characteristic curve and experimental data are performed for the optimization of the system working conditions, such as anode voltage, input power, working point and output power. Low anode voltage and nearly saturated input power amplifier can effectively increase the operating frequency. The simulation method is verified with the experimental data setup and the conventional 13-point approximate integral method. As a result, the relative error is less than 5%.
Numerical simulation of purge gas flow characteristics in randomly packed tritium breeder pebble bed
2015,
27: 096001.
doi: 10.11884/HPLPB201527.096001
Abstract:
Solid tritium breeder blanket is one of the most important blanket candidates for fusion reactor and fusion-fission hybrid reactor. The purge gas flow characteristics in the channels of pebble bed are important for the effective extraction of bred tritium from the solid breeder materials. A random packed structure of breeder pebbles, generated by Discrete Element Method (DEM), is verified by radial porosity distribution. The flow field parameters of the purge gas in channels are solved by Computational Fluid Dynamics (CFD) solver. The numerical analysis shows the velocity of the purge helium fluctuates with porosity distribution and uniformly increases with increasing inlet velocity, remarkable changes of flow direction and velocity occur in the channels. Blake-Kozeny equation is well applied to predicting the pressure drop in this random packed pebble bed.
Solid tritium breeder blanket is one of the most important blanket candidates for fusion reactor and fusion-fission hybrid reactor. The purge gas flow characteristics in the channels of pebble bed are important for the effective extraction of bred tritium from the solid breeder materials. A random packed structure of breeder pebbles, generated by Discrete Element Method (DEM), is verified by radial porosity distribution. The flow field parameters of the purge gas in channels are solved by Computational Fluid Dynamics (CFD) solver. The numerical analysis shows the velocity of the purge helium fluctuates with porosity distribution and uniformly increases with increasing inlet velocity, remarkable changes of flow direction and velocity occur in the channels. Blake-Kozeny equation is well applied to predicting the pressure drop in this random packed pebble bed.
Measurement of effective delayed neutron fraction in highly enriched uranium metal critical assembly
2015,
27: 096002.
doi: 10.11884/HPLPB201527.096002
Abstract:
Effective delayed neutron fraction eff is an important parameter in dynamic behaviour of nuclear reactor. Besides, eff has the role of the conversion factor between a relative unit and an absolute unit in reactivity scale, which is important for examining work of macroparameter according to reactivity. An experiment was performed to measure theeff in a fast critical assembly using Nelson number method which is based on Rossi- method. Using lead for shielding, adopting the thinner 6Li glass scintillator and pulse amplitude discrimination, the influence of is decreased. The measurements were carried out for reactivity ranging from -60 ￠ to delayed critical state. The final measured value ofeff is 0.006 66, with 7.88% uncertainty, of which the deviation is 2.15% compared with the theoretical value. Because of the good matching between the measured value and the theoretical value, the experiment method is demonstrated to be effective.
Effective delayed neutron fraction eff is an important parameter in dynamic behaviour of nuclear reactor. Besides, eff has the role of the conversion factor between a relative unit and an absolute unit in reactivity scale, which is important for examining work of macroparameter according to reactivity. An experiment was performed to measure theeff in a fast critical assembly using Nelson number method which is based on Rossi- method. Using lead for shielding, adopting the thinner 6Li glass scintillator and pulse amplitude discrimination, the influence of is decreased. The measurements were carried out for reactivity ranging from -60 ￠ to delayed critical state. The final measured value ofeff is 0.006 66, with 7.88% uncertainty, of which the deviation is 2.15% compared with the theoretical value. Because of the good matching between the measured value and the theoretical value, the experiment method is demonstrated to be effective.
2015,
27: 096003.
doi: 10.11884/HPLPB201527.096003
Abstract:
Due to that no cross flow exists in pressure tube embedded plate-type fuel component, the flow blockage accidents are apt to occur under some conditions, i.e., irradiation swelling of fuel or fragments entering into the cooling channel. The accidents may deteriorate the cooling condition and result in the phenomenon of departuring from nucleate boiling. Considering the special flow characteristics of the long and curved paths in fusion-fission hybrid energy reactor blanket, a simulation method with multi-scale thermal model is proposed. The boundary conditions calculated by RELAP5 code are provided to computational fluid dynamics (CFD) code. The thermal characteristics of the fuel component which has the largest deposited power density under partial and total flow blockage accidents are simulated. The results indicate that the fuel temperature still meet thermal safety criterion when the single cooling channel partially blocked. The peak temperature of fuel component will exceed the limit of phase-transition temperature when totally blocked.
Due to that no cross flow exists in pressure tube embedded plate-type fuel component, the flow blockage accidents are apt to occur under some conditions, i.e., irradiation swelling of fuel or fragments entering into the cooling channel. The accidents may deteriorate the cooling condition and result in the phenomenon of departuring from nucleate boiling. Considering the special flow characteristics of the long and curved paths in fusion-fission hybrid energy reactor blanket, a simulation method with multi-scale thermal model is proposed. The boundary conditions calculated by RELAP5 code are provided to computational fluid dynamics (CFD) code. The thermal characteristics of the fuel component which has the largest deposited power density under partial and total flow blockage accidents are simulated. The results indicate that the fuel temperature still meet thermal safety criterion when the single cooling channel partially blocked. The peak temperature of fuel component will exceed the limit of phase-transition temperature when totally blocked.
2015,
27: 099001.
doi: 10.11884/HPLPB201527.099001
Abstract:
Graphene is a fascinating material and it has many exceptional properties. The outstanding mechanical properties make it an ideal reinforcement material for metal matrix composites (MMCs). In this work, graphene reinforced copper nanocomposites were successfully prepared by laser sintering. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. It was proved by XRD patterns and Raman spectrum that graphene existed in the laser sintering composites. The Vickers hardness was measured; compared with laser sintered pure copper, a 22% increase in Vickers hardness value was obtained. The corrosion behaviors of laser sintered pure copper and graphene-copper composites in 3.5% NaCl solution were studied by electrochemical polarization method. The result shows that the corrosion resistance of graphene-copper composites is a little bit better than that of pure copper.
Graphene is a fascinating material and it has many exceptional properties. The outstanding mechanical properties make it an ideal reinforcement material for metal matrix composites (MMCs). In this work, graphene reinforced copper nanocomposites were successfully prepared by laser sintering. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. It was proved by XRD patterns and Raman spectrum that graphene existed in the laser sintering composites. The Vickers hardness was measured; compared with laser sintered pure copper, a 22% increase in Vickers hardness value was obtained. The corrosion behaviors of laser sintered pure copper and graphene-copper composites in 3.5% NaCl solution were studied by electrochemical polarization method. The result shows that the corrosion resistance of graphene-copper composites is a little bit better than that of pure copper.
2015,
27: 099002.
doi: 10.11884/HPLPB201527.099002
Abstract:
Serious slagging and ash deposition issues occur in combustion of Zhundong coal in industrial power plants due to its high content of alkali (Na, K). In this study, Zhundong coal was treated by chemical methods to make a lot of coal samples with a large range of Na and K concentrations. The results of Inductively Coupled Plasma Spectroscopy (ICP) were used as known variables for the calibration and prediction of Na and K content using laser-induced breakdown spectrum (LIBS).The results showed the measurements of Na and K by LIBS had high sensitivity, low detection limit and low Root Mean Square Prediction Error (RMSEP). The lower element concentration the sample contained, the greater the RSD was. When the element concentration reached a certain value, the RSD of measurement became stable. A large number of repeated measurements can guarantee the accuracy of LIBS measurement. Because LIBS technology itself has the advantage of fast measurement，LIBS could be a valid method to achieve online measurement of alkali content in coal.
Serious slagging and ash deposition issues occur in combustion of Zhundong coal in industrial power plants due to its high content of alkali (Na, K). In this study, Zhundong coal was treated by chemical methods to make a lot of coal samples with a large range of Na and K concentrations. The results of Inductively Coupled Plasma Spectroscopy (ICP) were used as known variables for the calibration and prediction of Na and K content using laser-induced breakdown spectrum (LIBS).The results showed the measurements of Na and K by LIBS had high sensitivity, low detection limit and low Root Mean Square Prediction Error (RMSEP). The lower element concentration the sample contained, the greater the RSD was. When the element concentration reached a certain value, the RSD of measurement became stable. A large number of repeated measurements can guarantee the accuracy of LIBS measurement. Because LIBS technology itself has the advantage of fast measurement，LIBS could be a valid method to achieve online measurement of alkali content in coal.
2015,
27: 099003.
doi: 10.11884/HPLPB201527.099003
Abstract:
The directivity patterns of the ultrasonic field induced by an oblique laser are investigated. The longitudinal wave and shear wave are respectively received by a piezoelectric transducer and an electromagnetic acoustic transducer in a state of micro ablation. At first, according to the ultrasound speeds, the signal types are determined. Then the directivity patterns are obtained by drawing peak to peak curve in the polar coordinate. The directivity patterns with normal axis of longitudinal wave do not change obviously for incidence angles in the range of 0-60, and angles for the maximum amplitude of shear wave still remain at 35 and -35. However, the main lobe of the directivity patterns for shear wave is sensitive to the incidence angle. In another word, shear wave amplitude near the normal increases with the incidence angle, especially when the inclined angle is no less than 45.
The directivity patterns of the ultrasonic field induced by an oblique laser are investigated. The longitudinal wave and shear wave are respectively received by a piezoelectric transducer and an electromagnetic acoustic transducer in a state of micro ablation. At first, according to the ultrasound speeds, the signal types are determined. Then the directivity patterns are obtained by drawing peak to peak curve in the polar coordinate. The directivity patterns with normal axis of longitudinal wave do not change obviously for incidence angles in the range of 0-60, and angles for the maximum amplitude of shear wave still remain at 35 and -35. However, the main lobe of the directivity patterns for shear wave is sensitive to the incidence angle. In another word, shear wave amplitude near the normal increases with the incidence angle, especially when the inclined angle is no less than 45.
