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RSS2015 Vol. 27, No. 01
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2015,
27: 010101.
doi: 10.11884/HPLPB201527.010101
Abstract:
A 1.5 kW all-fiber linearly-polarized fiber laser is reported. The laser adopts a scheme of MOPA structure which consists of an oscillator and a one-step power amplifier. The oscillator operates at a center wavelength of 1080 nm with an output power of 30 W, which is amplified to nearly diffraction-limited output of 1.5 kW by the one-step amplifier. The optical-optical efficiency is about 81.5% and the PER (Polarization-Extinction-Ratio) is about 13.8 dB. It is the highest output power of linearly polarized laser up to now.
A 1.5 kW all-fiber linearly-polarized fiber laser is reported. The laser adopts a scheme of MOPA structure which consists of an oscillator and a one-step power amplifier. The oscillator operates at a center wavelength of 1080 nm with an output power of 30 W, which is amplified to nearly diffraction-limited output of 1.5 kW by the one-step amplifier. The optical-optical efficiency is about 81.5% and the PER (Polarization-Extinction-Ratio) is about 13.8 dB. It is the highest output power of linearly polarized laser up to now.
2015,
27: 010102.
doi: 10.11884/HPLPB201527.010102
Abstract:
3D simulations of X-pinch are performed with FOI-PERFECT which is a 3D Rad-MHD program specifically developed for Z-pinch simulations. The physical picture and dynamic processes of X-pinch are given out. The possibility of magnetic reconnection occurring in Z-pinch is discussed. We point out that if the magnetic reconnection can occur in parallel two-wires Z-pinch, then the X-pinch is a more conducive configuration to magnetic reconnection, and the magnetic reconnection occurring in multiple z-axial locations is a possible reason for the multiple X-ray bursts appearing in X-pinch.
3D simulations of X-pinch are performed with FOI-PERFECT which is a 3D Rad-MHD program specifically developed for Z-pinch simulations. The physical picture and dynamic processes of X-pinch are given out. The possibility of magnetic reconnection occurring in Z-pinch is discussed. We point out that if the magnetic reconnection can occur in parallel two-wires Z-pinch, then the X-pinch is a more conducive configuration to magnetic reconnection, and the magnetic reconnection occurring in multiple z-axial locations is a possible reason for the multiple X-ray bursts appearing in X-pinch.
2015,
27: 010103.
doi: 10.11884/HPLPB201527.010103
Abstract:
A 476 W 1018 nm ytterbium fiber laser has been demonstrated employing large mode area fiber. A high power ytterbium doped fiber amplifier pumped by 6 high brightness 1018 nm fiber lasers is constructed. The maximum output power is 2140 W, with a slope efficiency as high as 86.9%. The beam quality M2 factor is measured to be 1.9. Further power scaling is very probable if more powerful pump sources are provided.
A 476 W 1018 nm ytterbium fiber laser has been demonstrated employing large mode area fiber. A high power ytterbium doped fiber amplifier pumped by 6 high brightness 1018 nm fiber lasers is constructed. The maximum output power is 2140 W, with a slope efficiency as high as 86.9%. The beam quality M2 factor is measured to be 1.9. Further power scaling is very probable if more powerful pump sources are provided.
2015,
27: 010201.
doi: 10.11884/HPLPB201527.010201
Abstract:
In this final article of the review series, Repetition rate pulsed power technology and its applications, the technological problems and the design difficulties are summarized. The operation parameters of a pulsed power system are mostly limited by the switching elements. The technical barriers are mainly cooling, efficiency, and reliability related issues. In addition, the complicated trade-off relations encountered in the pulsed power development are briefly explained. Management of these relations are fundamental engineering challenges for most pulsed power systems. Finally, from the authors viewpoint, the future development trends of this technology are discussed. The repetitive pulsed power technology will expectedly develop toward modularization, generalization, and intellectualization.
In this final article of the review series, Repetition rate pulsed power technology and its applications, the technological problems and the design difficulties are summarized. The operation parameters of a pulsed power system are mostly limited by the switching elements. The technical barriers are mainly cooling, efficiency, and reliability related issues. In addition, the complicated trade-off relations encountered in the pulsed power development are briefly explained. Management of these relations are fundamental engineering challenges for most pulsed power systems. Finally, from the authors viewpoint, the future development trends of this technology are discussed. The repetitive pulsed power technology will expectedly develop toward modularization, generalization, and intellectualization.
2015,
27: 010202.
doi: 10.11884/HPLPB201527.010202
Abstract:
The dielectric wall accelerator (DWA) is hot since it can work with accelerating gradient more than 50 MeV/m and has potential application to the proton cancer therapy. At the same time, a new concept accelerator DWA is under developing, while there are many technological and engineering problems to be solved. In this paper, the efforts to develop a 1 MeV proton injector based on DWA at CAEP are introduced. The samples of the high gradient insulator are made and tested under pulsed voltage mode, and can survive without flashover under the electric field of 160 kV/cm (120 ns, FWHM). The solid state pulsed power generator which consists of 15 Blumlein lines and corresponding photoconductive semiconductor switches can output voltage pulse up to 300 kV with a duration of 10 ns. A proton source is also developed for the 1 MeV proton injector.
The dielectric wall accelerator (DWA) is hot since it can work with accelerating gradient more than 50 MeV/m and has potential application to the proton cancer therapy. At the same time, a new concept accelerator DWA is under developing, while there are many technological and engineering problems to be solved. In this paper, the efforts to develop a 1 MeV proton injector based on DWA at CAEP are introduced. The samples of the high gradient insulator are made and tested under pulsed voltage mode, and can survive without flashover under the electric field of 160 kV/cm (120 ns, FWHM). The solid state pulsed power generator which consists of 15 Blumlein lines and corresponding photoconductive semiconductor switches can output voltage pulse up to 300 kV with a duration of 10 ns. A proton source is also developed for the 1 MeV proton injector.
2015,
27: 011001.
doi: 10.11884/HPLPB201527.011001
Abstract:
Based on Halbach array permanent magnets and the magnetic field demand of optical isolator, two permanent magnet systems for high power isolator are presented. The magnetic field distribution characteristics and the effect of magnetic field inhomogeneity on isolation are analyzed. The magnet assembly error is also discussed. The results show that, the use of oblique magnetization magnet can increase the magnetic field intensity and drastically reduce the required magnetooptic crystal length of Faraday rotator. And the isolation affected by magnetic field inhomogeneity is related to magneto optic crystal aperture, length and the incident laser beam radius, it can be significantly improved by reducing crystal radius and beam radius while magneto-optic crystal length is fixed. The isolation degree is 105.8 dB and 45.4 dB respectively for the proposed two permanent magnet systems, when the radius of incident light is 1.5 mm and magneto-optic crystal radius is 5 mm.
Based on Halbach array permanent magnets and the magnetic field demand of optical isolator, two permanent magnet systems for high power isolator are presented. The magnetic field distribution characteristics and the effect of magnetic field inhomogeneity on isolation are analyzed. The magnet assembly error is also discussed. The results show that, the use of oblique magnetization magnet can increase the magnetic field intensity and drastically reduce the required magnetooptic crystal length of Faraday rotator. And the isolation affected by magnetic field inhomogeneity is related to magneto optic crystal aperture, length and the incident laser beam radius, it can be significantly improved by reducing crystal radius and beam radius while magneto-optic crystal length is fixed. The isolation degree is 105.8 dB and 45.4 dB respectively for the proposed two permanent magnet systems, when the radius of incident light is 1.5 mm and magneto-optic crystal radius is 5 mm.
2015,
27: 011002.
doi: 10.11884/HPLPB201527.011002
Abstract:
The transmission performance will be affected by scintillation while the coherent light is propagating through turbulence in atmosphere. Theoretical research shows that the effect can be deduced by using partially coherent light. However, there is few related experimental verification up to now. In this work, turbulence with Rytov variance of 0.04~0.16 was generated by a turbulence emulator of aqueous medium. Transmission experiment of partially coherent light and coherent light in weak turbulence was conducted. Scintillation index was obtained as a function of Rytov variance by analyzing the received intensity. The analysis shows that the scintillation indexes of partially coherent light and coherent light increase with the increase of strength of turbulence, however, the scintillation index of coherent light is larger than that of partially coherent light, which is consistent with the theoretical model of Gaussian Schell beam established by Andrews et al.
The transmission performance will be affected by scintillation while the coherent light is propagating through turbulence in atmosphere. Theoretical research shows that the effect can be deduced by using partially coherent light. However, there is few related experimental verification up to now. In this work, turbulence with Rytov variance of 0.04~0.16 was generated by a turbulence emulator of aqueous medium. Transmission experiment of partially coherent light and coherent light in weak turbulence was conducted. Scintillation index was obtained as a function of Rytov variance by analyzing the received intensity. The analysis shows that the scintillation indexes of partially coherent light and coherent light increase with the increase of strength of turbulence, however, the scintillation index of coherent light is larger than that of partially coherent light, which is consistent with the theoretical model of Gaussian Schell beam established by Andrews et al.
2015,
27: 011003.
doi: 10.11884/HPLPB201527.011003
Abstract:
Through the study of the demodulation algorithm including the searching peak algorithm and fitting algorithm on the collected data (the domain signals of the Fabry-Perot (F-P) etalon transmission spectrum and fiber Bragg grating (FBG) sensors reflection spectrum) by the system, the FBG wavelength signal demodulation is achieved by way of combining C language programming with LabVIEW. As the collected data points consisted of the time-domain signals of F-P etalon transmission spectrum and FBG reflection spectrum by the system are discrete, and within 3 dB bandwidth the time-domain signal spectra of F-P etalon and FBG are in line with a Gaussian curve distribution, the Gaussian fitting is used for the collected data points to find the time point corresponding to the signal peak to improve system precision; Also, because of the certain nonlinearity of the distributed feedback laser (DFB) laser scanning wavelength with the scanning time, the binomial curve fitting is used to reduce the error caused by the nonlinearity. In addition, a standard FBG sensing channel is set for wavelength calibration. Experimental studies show that the system has a good stability, the wavelength measurement range is 1 550.012-1 554.812 nm, the resolution is 1 pm, the precision is 10 pm, verifying the feasibility of the system applying to the FBG wavelength signal detection.
Through the study of the demodulation algorithm including the searching peak algorithm and fitting algorithm on the collected data (the domain signals of the Fabry-Perot (F-P) etalon transmission spectrum and fiber Bragg grating (FBG) sensors reflection spectrum) by the system, the FBG wavelength signal demodulation is achieved by way of combining C language programming with LabVIEW. As the collected data points consisted of the time-domain signals of F-P etalon transmission spectrum and FBG reflection spectrum by the system are discrete, and within 3 dB bandwidth the time-domain signal spectra of F-P etalon and FBG are in line with a Gaussian curve distribution, the Gaussian fitting is used for the collected data points to find the time point corresponding to the signal peak to improve system precision; Also, because of the certain nonlinearity of the distributed feedback laser (DFB) laser scanning wavelength with the scanning time, the binomial curve fitting is used to reduce the error caused by the nonlinearity. In addition, a standard FBG sensing channel is set for wavelength calibration. Experimental studies show that the system has a good stability, the wavelength measurement range is 1 550.012-1 554.812 nm, the resolution is 1 pm, the precision is 10 pm, verifying the feasibility of the system applying to the FBG wavelength signal detection.
2015,
27: 011004.
doi: 10.11884/HPLPB201527.011004
Abstract:
The expressions for the turbulence distance of partially coherent Flat-topped beams propagating through non-Kolmogorov turbulence is derived, and the influence of generalized exponent parameter of the atmospheric power spectrum, inner scale, outer scale and the beam parameters on the turbulence distance is studied. It is shown that turbulence distance decreases with increasing coherence parameter, waist width and outer scale (for generalized exponent parameter of the atmospheric power spectrum in the range of 3.6-4.0), but increases with increasing beam orders and inner scale. However, turbulence distance does not monotonically vary with the increase of generalized exponent parameter of the atmospheric power spectrum, it decreases firstly and then increases. When the value of generalized exponent parameter of the atmospheric power spectrum is 3.11, turbulence distance reaches its minima, which means that the spreading of beams is the largest. The turbulence distance and Rayleigh range are compared by using generalized exponent parameter of the atmospheric power spectrum and the beam parameters, and it shows that whether the spreading is affected by turbulence within Rayleigh range is determined by generalized exponent parameter of the atmospheric power spectrum and the beam parameters. Key words:
The expressions for the turbulence distance of partially coherent Flat-topped beams propagating through non-Kolmogorov turbulence is derived, and the influence of generalized exponent parameter of the atmospheric power spectrum, inner scale, outer scale and the beam parameters on the turbulence distance is studied. It is shown that turbulence distance decreases with increasing coherence parameter, waist width and outer scale (for generalized exponent parameter of the atmospheric power spectrum in the range of 3.6-4.0), but increases with increasing beam orders and inner scale. However, turbulence distance does not monotonically vary with the increase of generalized exponent parameter of the atmospheric power spectrum, it decreases firstly and then increases. When the value of generalized exponent parameter of the atmospheric power spectrum is 3.11, turbulence distance reaches its minima, which means that the spreading of beams is the largest. The turbulence distance and Rayleigh range are compared by using generalized exponent parameter of the atmospheric power spectrum and the beam parameters, and it shows that whether the spreading is affected by turbulence within Rayleigh range is determined by generalized exponent parameter of the atmospheric power spectrum and the beam parameters. Key words:
2015,
27: 011005.
doi: 10.11884/HPLPB201527.011005
Abstract:
With the power-law wavelength dependence of aerosol absorption optical depth (AAOD), aerosol absorption properties of typical types were studied. The effect of relative humidity on aerosol absorption properties and absorption Angstrom exponent were also analyzed upon different aerosol types containing different compositions. The results show that the power-law wavelength dependence of AAOD is not satisfied at all available wavelength, different aerosol types have differently suitable wavelength range. Relative humidity affects AAOD, this is mainly due to aerosol compositions are influenced by relative humidity. Increasing of relative humidity will lead to a decrease in aerosol absorption. Relative humidity can also affect AAE. The universal law of AAOD of typical types varying with relative humidity and wavelength is obtained.
With the power-law wavelength dependence of aerosol absorption optical depth (AAOD), aerosol absorption properties of typical types were studied. The effect of relative humidity on aerosol absorption properties and absorption Angstrom exponent were also analyzed upon different aerosol types containing different compositions. The results show that the power-law wavelength dependence of AAOD is not satisfied at all available wavelength, different aerosol types have differently suitable wavelength range. Relative humidity affects AAOD, this is mainly due to aerosol compositions are influenced by relative humidity. Increasing of relative humidity will lead to a decrease in aerosol absorption. Relative humidity can also affect AAE. The universal law of AAOD of typical types varying with relative humidity and wavelength is obtained.
2015,
27: 011006.
doi: 10.11884/HPLPB201527.011006
Abstract:
Vacuum magnetron sputtering technology was used to prepare three kinds of composite films: CuO/Al2O3/Al,(CuO/Al)Ⅱ/CuO/ Al2O3/Al,and (CuO/Al)Ⅷ/ Al2O3/Al, and the performance of the materials were characterized by scanning electron microscopy and confocal microscopy. The results showed that the surface of the films were smooth, and the interfaces between different layers were compact. Then, photonic Doppler velocimetry was used to measure the speeds of the flyers. The results showed that the flyers were placed in front of the position where the air was ionized by laser so that energy shielding effect caused by laser ionization of air could be improved. Besides, the energetic film as an ablative layer such as CuO/Al helped to improve the speed of flyers. When the thickness of the ablation layer was unchanged, the way of increasing cycle and reducing the film thickness of each layer was used to improve the degree of reaction and reduce the rising time. On the condition of the same laser energy density, that of (CuO/Al)Ⅷ/ Al2O3/Al was less than that of (CuO/Al)Ⅱ/CuO/Al2O3/Al.
Vacuum magnetron sputtering technology was used to prepare three kinds of composite films: CuO/Al2O3/Al,(CuO/Al)Ⅱ/CuO/ Al2O3/Al,and (CuO/Al)Ⅷ/ Al2O3/Al, and the performance of the materials were characterized by scanning electron microscopy and confocal microscopy. The results showed that the surface of the films were smooth, and the interfaces between different layers were compact. Then, photonic Doppler velocimetry was used to measure the speeds of the flyers. The results showed that the flyers were placed in front of the position where the air was ionized by laser so that energy shielding effect caused by laser ionization of air could be improved. Besides, the energetic film as an ablative layer such as CuO/Al helped to improve the speed of flyers. When the thickness of the ablation layer was unchanged, the way of increasing cycle and reducing the film thickness of each layer was used to improve the degree of reaction and reduce the rising time. On the condition of the same laser energy density, that of (CuO/Al)Ⅷ/ Al2O3/Al was less than that of (CuO/Al)Ⅱ/CuO/Al2O3/Al.
2015,
27: 011007.
doi: 10.11884/HPLPB201527.011007
Abstract:
Due to the small temperature difference between target and background in the scene, infrared image usually has a low contrast and poor visual effect. In order to solve this problem, a novel enhancement method for low-contrast infrared image is proposed based on nonlinear correction of singular values in real time. Firstly, the infrared image is processed by means of singular value decomposition to obtain the original singular values. Then, logarithmically nonlinear transformation is adopted to optimize singular values. Finally, the enhanced infrared image is reconstructed with new singular values corrected. Using logarithmically nonlinear transform can stretch the dynamic range of singular values, and optimize gradient of singular values with the result that the energy information of infrared image can be expressed fully and that the quality of infrared image can be improved effectively. The experimental results show that the proposed method outperforms other methods in terms of visual effect and objective evaluation and also reflects a good real-time performance, which provides a new approach for the realization of real-time infrared image enhancement.
Due to the small temperature difference between target and background in the scene, infrared image usually has a low contrast and poor visual effect. In order to solve this problem, a novel enhancement method for low-contrast infrared image is proposed based on nonlinear correction of singular values in real time. Firstly, the infrared image is processed by means of singular value decomposition to obtain the original singular values. Then, logarithmically nonlinear transformation is adopted to optimize singular values. Finally, the enhanced infrared image is reconstructed with new singular values corrected. Using logarithmically nonlinear transform can stretch the dynamic range of singular values, and optimize gradient of singular values with the result that the energy information of infrared image can be expressed fully and that the quality of infrared image can be improved effectively. The experimental results show that the proposed method outperforms other methods in terms of visual effect and objective evaluation and also reflects a good real-time performance, which provides a new approach for the realization of real-time infrared image enhancement.
2015,
27: 011008.
doi: 10.11884/HPLPB201527.011008
Abstract:
A static aero elastic model of hypersonic aircraft under laser irradiation was built based on computational fluid dynamics (CFD) and computational structural dynamics coupling numerical computational methodology. The flow was governed by 3-D Reynolds averaged Navier-Stokes equations. To split the viscosity flux and the convective flux of the NS equations, the second order central scheme and the AUSM+up scheme were adopted respectively. With the implicit Gauss-Seidel scheme, the code was advanced in time. The Menter SST turbulence model was used for turbulence simulations. The model was proofread with the experiment data from von Karman Institute hypersonic wind tunnel. Hypersonic aircraft wing under laser irradiation was simulated with this model. The results indicated that the energy addition could reduce the Youngs modulus of hypersonic rudder. Hypersonic aircraft may prang due to the destroy of the rudder.
A static aero elastic model of hypersonic aircraft under laser irradiation was built based on computational fluid dynamics (CFD) and computational structural dynamics coupling numerical computational methodology. The flow was governed by 3-D Reynolds averaged Navier-Stokes equations. To split the viscosity flux and the convective flux of the NS equations, the second order central scheme and the AUSM+up scheme were adopted respectively. With the implicit Gauss-Seidel scheme, the code was advanced in time. The Menter SST turbulence model was used for turbulence simulations. The model was proofread with the experiment data from von Karman Institute hypersonic wind tunnel. Hypersonic aircraft wing under laser irradiation was simulated with this model. The results indicated that the energy addition could reduce the Youngs modulus of hypersonic rudder. Hypersonic aircraft may prang due to the destroy of the rudder.
2015,
27: 011009.
doi: 10.11884/HPLPB201527.011009
Abstract:
In this paper, we first built a 3D model for diode pumped alkali vapor laser (DPAL) based on the three-level rate equations and split-step beam propagation method, which can be used to simulate the kinetic process of end-pumped single-pass Rb vapor laser. This model considered beam propagation and light interaction with matter respectively. This model was solved by the iteration method. As an example, the distribution for population inversion which is under the optimal mode-matching and gain through different axis was investigated. Then we calculated the influence of mode-matching on the threshold and explained this influence by the distribution of particles and light field distribution. Finally we analyzed the influence of the length of gain cell on threshold characteristics. It turned out that the parameter of the cavity is related to the mode of pumped laser. The threshold will be the minimum value when the cavity parameters and the pumped laser mode are properly selected.
In this paper, we first built a 3D model for diode pumped alkali vapor laser (DPAL) based on the three-level rate equations and split-step beam propagation method, which can be used to simulate the kinetic process of end-pumped single-pass Rb vapor laser. This model considered beam propagation and light interaction with matter respectively. This model was solved by the iteration method. As an example, the distribution for population inversion which is under the optimal mode-matching and gain through different axis was investigated. Then we calculated the influence of mode-matching on the threshold and explained this influence by the distribution of particles and light field distribution. Finally we analyzed the influence of the length of gain cell on threshold characteristics. It turned out that the parameter of the cavity is related to the mode of pumped laser. The threshold will be the minimum value when the cavity parameters and the pumped laser mode are properly selected.
2015,
27: 011010.
doi: 10.11884/HPLPB201527.011010
Abstract:
The thermo-mechanical model of the deformable mirror based on ANSYS multiphysics is provided and calculated. High energy laser radiation results in a mirror deformation of about 0.9 m. Therefore, according to the characteristic distribution of the thermally-induced deformation, a compensation method is proposed. The compensation mirror, placed in the optical path after the deformable mirror, is composed of a thin mirror and some restriction parts. By contrast with the poles of the deformable mirror, the restriction parts of the compensation mirror are installed in a staggered order. Three types of compensation mirrors with different shapes of restriction parts are calculated. The results show that the values of the thermal deformation reduce to 0.35 m, 0.32 m and 0.40 m. Using the BPF (beam propagation factor) to evaluate the compensation effect, the results indicate that the BPF value increases from 0.906 to 0.966, 0.971 and 0.957. Further calculations show that the size of the restriction parts has little effect on the compensation effect.
The thermo-mechanical model of the deformable mirror based on ANSYS multiphysics is provided and calculated. High energy laser radiation results in a mirror deformation of about 0.9 m. Therefore, according to the characteristic distribution of the thermally-induced deformation, a compensation method is proposed. The compensation mirror, placed in the optical path after the deformable mirror, is composed of a thin mirror and some restriction parts. By contrast with the poles of the deformable mirror, the restriction parts of the compensation mirror are installed in a staggered order. Three types of compensation mirrors with different shapes of restriction parts are calculated. The results show that the values of the thermal deformation reduce to 0.35 m, 0.32 m and 0.40 m. Using the BPF (beam propagation factor) to evaluate the compensation effect, the results indicate that the BPF value increases from 0.906 to 0.966, 0.971 and 0.957. Further calculations show that the size of the restriction parts has little effect on the compensation effect.
2015,
27: 011011.
doi: 10.11884/HPLPB201527.011011
Abstract:
By using the micro-thermal meters at different heights of a tower in Gobi area, refractive index structure parameters were continuously measured in the atmospheric surface layer for a long time. A statistical analysis on large numbers of experimental data on cumulative probability, skewness and kurtosis, seasonal variation, and empirical formula of refractive index structure parameter dependence on height is provided. The obtained results show that the cumulative probabilities in the measured area during day and night with 18 m as the distinction, exhibit significant difference between the measurement above 18m and the measurement under 18 m. The probability distribution of refractive index structure parameter at all heights show a right skewed, flat peak characteristics. Seasonal variation have more obvious influence on the refractive index structure parameter of lower levels. Empirical formula in measured area on refractive index structure parameter by day shows optical turbulence strength decreases with a -2/3 exponent altitude dependence. Whereas refractive index structure parameter of empirical formula at night shows levels, and optical turbulence of lower levels decreases with a -0.16 exponent altitude dependence, while the higher change with height close to the -1.05.
By using the micro-thermal meters at different heights of a tower in Gobi area, refractive index structure parameters were continuously measured in the atmospheric surface layer for a long time. A statistical analysis on large numbers of experimental data on cumulative probability, skewness and kurtosis, seasonal variation, and empirical formula of refractive index structure parameter dependence on height is provided. The obtained results show that the cumulative probabilities in the measured area during day and night with 18 m as the distinction, exhibit significant difference between the measurement above 18m and the measurement under 18 m. The probability distribution of refractive index structure parameter at all heights show a right skewed, flat peak characteristics. Seasonal variation have more obvious influence on the refractive index structure parameter of lower levels. Empirical formula in measured area on refractive index structure parameter by day shows optical turbulence strength decreases with a -2/3 exponent altitude dependence. Whereas refractive index structure parameter of empirical formula at night shows levels, and optical turbulence of lower levels decreases with a -0.16 exponent altitude dependence, while the higher change with height close to the -1.05.
2015,
27: 011012.
doi: 10.11884/HPLPB201527.011012
Abstract:
The fixed block size of source images will result in blocking artifacts, fuzzy edge and focus error in multi-focus image fusion. To solve this problem, a new multi-focus image fusion algorithm based on block optimization using artificial fish-swarm is proposed. Firstly, the source images are decomposed into non-overlapping blocks and the sharper blocks are selected using a sharpness criterion. The selected blocks are combined to construct the initial fused image. Then, an improved artificial fish-swarm algorithm is used to optimize the block size according to a fitness function. The final fused image is obtained based on the best block size. Experimental results show that the proposed fusion method has a good quantitative evaluation and visual effect compared to other traditional methods.
The fixed block size of source images will result in blocking artifacts, fuzzy edge and focus error in multi-focus image fusion. To solve this problem, a new multi-focus image fusion algorithm based on block optimization using artificial fish-swarm is proposed. Firstly, the source images are decomposed into non-overlapping blocks and the sharper blocks are selected using a sharpness criterion. The selected blocks are combined to construct the initial fused image. Then, an improved artificial fish-swarm algorithm is used to optimize the block size according to a fitness function. The final fused image is obtained based on the best block size. Experimental results show that the proposed fusion method has a good quantitative evaluation and visual effect compared to other traditional methods.
2015,
27: 011013.
doi: 10.11884/HPLPB201527.011013
Abstract:
In order to solve the problem of finding the sniper quickly in security, a system using the cat-eye effect principle of sniper scope to find a target is designed. The system is different from that of traditional design of lighting source. It is a system based on semiconductor modulated laser, which replaces CW laser source, and works with modulated signal to scan the field. A CCD is used to capture the active and passive echo image. According to the target echoes image at different distance, the algorithm can be implemented in embedded DSP high-speed processing platform for the near and far targets respectively. The results, obtained in the field experimental, showed that the new system increases the detection rate, and reduces the incidence of false alarms. The system accurately detected the target of 300m and 800m in distance with a real-time processing speed of 10 fps.
In order to solve the problem of finding the sniper quickly in security, a system using the cat-eye effect principle of sniper scope to find a target is designed. The system is different from that of traditional design of lighting source. It is a system based on semiconductor modulated laser, which replaces CW laser source, and works with modulated signal to scan the field. A CCD is used to capture the active and passive echo image. According to the target echoes image at different distance, the algorithm can be implemented in embedded DSP high-speed processing platform for the near and far targets respectively. The results, obtained in the field experimental, showed that the new system increases the detection rate, and reduces the incidence of false alarms. The system accurately detected the target of 300m and 800m in distance with a real-time processing speed of 10 fps.
2015,
27: 011014.
doi: 10.11884/HPLPB201527.011014
Abstract:
In order to reduce the effect that caused by background edge of the infrared image, a robust small target detection algorithm is proposed. Firstly, a kernel anisotropic diffusion model is used to predict the background. Then, targets are extracted from the residual map between the original image and its predicted background image. In order to improve the algorithms adaptive ability, a robust diffusion parameter is proposed which can automatically adjust diffusion parameter based on the fluctuation of the images background. The experimental results demonstrate that the proposed algorithm has better performance in the suppression of background and its edge, the reservation of targets size, the reduction of false-alarm probability, and the robustness compared with the state-of-the-art algorithms under various typical complex backgrounds.
In order to reduce the effect that caused by background edge of the infrared image, a robust small target detection algorithm is proposed. Firstly, a kernel anisotropic diffusion model is used to predict the background. Then, targets are extracted from the residual map between the original image and its predicted background image. In order to improve the algorithms adaptive ability, a robust diffusion parameter is proposed which can automatically adjust diffusion parameter based on the fluctuation of the images background. The experimental results demonstrate that the proposed algorithm has better performance in the suppression of background and its edge, the reservation of targets size, the reduction of false-alarm probability, and the robustness compared with the state-of-the-art algorithms under various typical complex backgrounds.
2015,
27: 011015.
doi: 10.11884/HPLPB201527.011015
Abstract:
It is meaningful to integrate the atmospheric scintillation measurement on the far field speckles projection imaging system for comprehensively analyzing the characteristics of laser atmospheric propagation and its influence on the photoelectric system. However, the atmospheric scintillation will become very weak at large receiving aperture because of aperture averaging effect, and the intensity fluctuation induced by laser source stability will become obvious. Therefore, an atmospheric scintillation measurement model considering the laser source intensity fluctuation is established based on the multiply stochastic process assumption of laser source intensity fluctuation and atmospheric scintillation. Using the characteristic that the laser source intensity fluctuation does not vary with aperture and the atmospheric scintillation varies with aperture, the atmospheric scintillation and laser source intensity fluctuation can be estimated respectively through the measurement model by combining the aperture averaging factor in weak fluctuation and the intensity scintillation measurement result with different receiving aperture at the same time in the projector optics. The experiment results show that the relative error between theoretical prediction and experimental values is below 9.685% at the aperture from 0.05 m to 0.40 m. This method could estimate the atmospheric scintillation in weak turbulence fluctuation based on the projection optics system.
It is meaningful to integrate the atmospheric scintillation measurement on the far field speckles projection imaging system for comprehensively analyzing the characteristics of laser atmospheric propagation and its influence on the photoelectric system. However, the atmospheric scintillation will become very weak at large receiving aperture because of aperture averaging effect, and the intensity fluctuation induced by laser source stability will become obvious. Therefore, an atmospheric scintillation measurement model considering the laser source intensity fluctuation is established based on the multiply stochastic process assumption of laser source intensity fluctuation and atmospheric scintillation. Using the characteristic that the laser source intensity fluctuation does not vary with aperture and the atmospheric scintillation varies with aperture, the atmospheric scintillation and laser source intensity fluctuation can be estimated respectively through the measurement model by combining the aperture averaging factor in weak fluctuation and the intensity scintillation measurement result with different receiving aperture at the same time in the projector optics. The experiment results show that the relative error between theoretical prediction and experimental values is below 9.685% at the aperture from 0.05 m to 0.40 m. This method could estimate the atmospheric scintillation in weak turbulence fluctuation based on the projection optics system.
2015,
27: 012001.
doi: 10.11884/HPLPB201527.012001
Abstract:
In order to improve the laser damage resistance of fused silica optical surfaces, the appearance of smoothed fused silica surface defect and the effect of wiping off etching contamination are researched on HF-based etching processes under ultrasonic. And the experimental parameters are determined with SEM microscopy and atomic force microscopy to record face appearance and with one pulse laser incidence to measure laser damage threshold. Results show that it is advantageous to use HF-based etching processes under ultrasonic to smooth the defected surfaces and wipe off micrometer contamination particles. By experimental measurement, the parameters of HF-based etching processes under ultrasonic are obtained for different kinds of fused silica optics. The present research is very important for improving laser damage resistance of fused silica.
In order to improve the laser damage resistance of fused silica optical surfaces, the appearance of smoothed fused silica surface defect and the effect of wiping off etching contamination are researched on HF-based etching processes under ultrasonic. And the experimental parameters are determined with SEM microscopy and atomic force microscopy to record face appearance and with one pulse laser incidence to measure laser damage threshold. Results show that it is advantageous to use HF-based etching processes under ultrasonic to smooth the defected surfaces and wipe off micrometer contamination particles. By experimental measurement, the parameters of HF-based etching processes under ultrasonic are obtained for different kinds of fused silica optics. The present research is very important for improving laser damage resistance of fused silica.
2015,
27: 012002.
doi: 10.11884/HPLPB201527.012002
Abstract:
In order to reduce the self-absorption effect of spectral lines in the laser induced plasma emission, which could improve the detection level of laser spectral analysis technology for high-content elements in materials, a plane mirror device was used to constraint plasma in the experiment. The change of the spectral lines with or without the plane mirror device was compared. Without the plane mirror device, the half-maximum line widths of spectral line of the sample element Al, Mg and Mn were 0.16 nm, 0.24 nm and 0.058 nm, respectively. But they were 0.11 nm, 0.13 nm and 0.047 nm with four plane mirrors device constraining plasma. It shows that the self-absorption effect of spectral lines decrease significantly by the use of plane mirror device to restrain plasma on the space, while the spectral line becomes sharper and the intensity is improved significantly. By observing the plasma photos and measuring of plasma temperature and electron density, the reason to reducing the self-absorption effect in laser spectrum is discussed.
In order to reduce the self-absorption effect of spectral lines in the laser induced plasma emission, which could improve the detection level of laser spectral analysis technology for high-content elements in materials, a plane mirror device was used to constraint plasma in the experiment. The change of the spectral lines with or without the plane mirror device was compared. Without the plane mirror device, the half-maximum line widths of spectral line of the sample element Al, Mg and Mn were 0.16 nm, 0.24 nm and 0.058 nm, respectively. But they were 0.11 nm, 0.13 nm and 0.047 nm with four plane mirrors device constraining plasma. It shows that the self-absorption effect of spectral lines decrease significantly by the use of plane mirror device to restrain plasma on the space, while the spectral line becomes sharper and the intensity is improved significantly. By observing the plasma photos and measuring of plasma temperature and electron density, the reason to reducing the self-absorption effect in laser spectrum is discussed.
2015,
27: 013001.
doi: 10.11884/HPLPB201527.013001
Abstract:
The transmission characteristic of radial beam under an immersive focusing magnetic field is analyzed, and the analytic expression of beams axial expansion is derived theoretically. Then the theory of magnetic field generated by coils at any point in the space, with the law of magnetic field distribution in a pair of plane coils with different current direction is given. A kind of guiding magnetic field system based on plane coils is designed. The distribution of the magnetic field generated by the guiding magnetic field system along the beam channel and the particle trajectory under stable transmission is researched through simulation.
The transmission characteristic of radial beam under an immersive focusing magnetic field is analyzed, and the analytic expression of beams axial expansion is derived theoretically. Then the theory of magnetic field generated by coils at any point in the space, with the law of magnetic field distribution in a pair of plane coils with different current direction is given. A kind of guiding magnetic field system based on plane coils is designed. The distribution of the magnetic field generated by the guiding magnetic field system along the beam channel and the particle trajectory under stable transmission is researched through simulation.
2015,
27: 013002.
doi: 10.11884/HPLPB201527.013002
Abstract:
Using the equivalent circuit theory, we design a pill-box output window for Q-band high power gyrotron traveling wave tube (gyro-TWT) with a thickness of 1.32 mm. Through inserting the inductive diaphragms and changing the shape of the window, the designed pill-box output window can withstand an average power of 25 kW, the relative bandwidth is 14%, and its thickness is changed to 1.7 mm. This paper uses a high frequency software HFSS combined with a new method of collaborative simulation of finite element analysis software ANSYS to simulate the thermal characteristics of the pill-box output window. It shows that the new-type of pill-box can withstand an average power capacity of 25 kW at the bandwidth, and the temperature difference between center and edge of the window is 66 ℃, while the tolerance temperature is 158 ℃ of the ceramic window. Thus, it verifies the rationality of the new pill-box output window for Q-band high power gyro-TWT.
Using the equivalent circuit theory, we design a pill-box output window for Q-band high power gyrotron traveling wave tube (gyro-TWT) with a thickness of 1.32 mm. Through inserting the inductive diaphragms and changing the shape of the window, the designed pill-box output window can withstand an average power of 25 kW, the relative bandwidth is 14%, and its thickness is changed to 1.7 mm. This paper uses a high frequency software HFSS combined with a new method of collaborative simulation of finite element analysis software ANSYS to simulate the thermal characteristics of the pill-box output window. It shows that the new-type of pill-box can withstand an average power capacity of 25 kW at the bandwidth, and the temperature difference between center and edge of the window is 66 ℃, while the tolerance temperature is 158 ℃ of the ceramic window. Thus, it verifies the rationality of the new pill-box output window for Q-band high power gyro-TWT.
2015,
27: 013101.
doi: 10.11884/HPLPB201527.013101
Abstract:
Schottky diode is the critical component of terahertz receiver. The Schottky diode simulation model is established in HFSS to obtain the S-parameters of the Schottky diode in 0-120 GHz. The accuracy of the diode simulation model is proved by comparing S-parameters between simulated and measured results. The general packaging model and flip-chip packaging model of Schottky diodes are established, and two different S-parameters, -3 dB bandwidth and phase coherence are analyzed. The results show that the flip-chip packaging is more appropriate for THz Schottky diode than the general packaging, which can bring great improvement of electrical properties of Schottky diode in the high frequency applications.
Schottky diode is the critical component of terahertz receiver. The Schottky diode simulation model is established in HFSS to obtain the S-parameters of the Schottky diode in 0-120 GHz. The accuracy of the diode simulation model is proved by comparing S-parameters between simulated and measured results. The general packaging model and flip-chip packaging model of Schottky diodes are established, and two different S-parameters, -3 dB bandwidth and phase coherence are analyzed. The results show that the flip-chip packaging is more appropriate for THz Schottky diode than the general packaging, which can bring great improvement of electrical properties of Schottky diode in the high frequency applications.
2015,
27: 013102.
doi: 10.11884/HPLPB201527.013102
Abstract:
The most commonly used method was adopted to calculate the conductivity loss. This paper analyzed two kinds of theory formula to calculate the effective conductivity, and fabricated the folded waveguide slow-wave structure for testing. The test result shows that the effective conductivity of 0.14 THz folded waveguide structure in oxygen free copper is 4107 S/m when the surface roughness is 0.3 m, which is not consistent with the theory calculation. Finally, the reason for this discrepancy was discussed, and a modified theoretical formula was put forward.
The most commonly used method was adopted to calculate the conductivity loss. This paper analyzed two kinds of theory formula to calculate the effective conductivity, and fabricated the folded waveguide slow-wave structure for testing. The test result shows that the effective conductivity of 0.14 THz folded waveguide structure in oxygen free copper is 4107 S/m when the surface roughness is 0.3 m, which is not consistent with the theory calculation. Finally, the reason for this discrepancy was discussed, and a modified theoretical formula was put forward.
2015,
27: 014001.
doi: 10.11884/HPLPB201527.014001
Abstract:
Electron incident angles have a heavy effect on the energy deposition profile (EDP) in material of the intense pulsed electron beam. The average of electron incident angles must be taken into consideration when carrying out the diagnosis technology research and numerical simulation study, while a widely received method to solve the problem has not yet been presented. This article gives a qualitative analysis on the energy deposition function, which is formed by the energy loss function and energy deposition efficiency function. An average method of electron beam incident angles based on EDP, which is named as EDP average method, is developed, and a qualitative explanation of the electron beam EDP curve is given. The error and applicability of this method are analyzed. M-C tests are designed for comparison with theoretical analysis. The EDP average method has a better performance in calculation of the EDP than the method using arithmetic average directly, especially in the shallow of target material.
Electron incident angles have a heavy effect on the energy deposition profile (EDP) in material of the intense pulsed electron beam. The average of electron incident angles must be taken into consideration when carrying out the diagnosis technology research and numerical simulation study, while a widely received method to solve the problem has not yet been presented. This article gives a qualitative analysis on the energy deposition function, which is formed by the energy loss function and energy deposition efficiency function. An average method of electron beam incident angles based on EDP, which is named as EDP average method, is developed, and a qualitative explanation of the electron beam EDP curve is given. The error and applicability of this method are analyzed. M-C tests are designed for comparison with theoretical analysis. The EDP average method has a better performance in calculation of the EDP than the method using arithmetic average directly, especially in the shallow of target material.
2015,
27: 014002.
doi: 10.11884/HPLPB201527.014002
Abstract:
Geometric factor calculations play an important role in the absolute calibration of radioactivity measurement systems and in the determination of the activity of radioactive sources. The Monte Carlo method can always calculate the geometric factors when there is no analytical algorithm available for geometric factor calculations. Few papers have reported the calculations of geometric factors when source and detector are both disc, but are un-coaxial and un-parallel. The program in this study is based on the Monte Carlo method and is written in the C++ programming language, and it can be used to calculate the geometric factor of a disc detector for a disc source. The detector and the source can be any size at any cases. This program integrated a variance reduction method, by comparing. The results with that calculated using MCNP5. It can be concluded that the program calculates geometric factors accurately, fast and conveniently. The geometric factor calculation program verified the accuracy of the pose of the detector which was applied in the NDP energy spectrum measurement system; furthermore, it corrected the detector position roughly.
Geometric factor calculations play an important role in the absolute calibration of radioactivity measurement systems and in the determination of the activity of radioactive sources. The Monte Carlo method can always calculate the geometric factors when there is no analytical algorithm available for geometric factor calculations. Few papers have reported the calculations of geometric factors when source and detector are both disc, but are un-coaxial and un-parallel. The program in this study is based on the Monte Carlo method and is written in the C++ programming language, and it can be used to calculate the geometric factor of a disc detector for a disc source. The detector and the source can be any size at any cases. This program integrated a variance reduction method, by comparing. The results with that calculated using MCNP5. It can be concluded that the program calculates geometric factors accurately, fast and conveniently. The geometric factor calculation program verified the accuracy of the pose of the detector which was applied in the NDP energy spectrum measurement system; furthermore, it corrected the detector position roughly.
2015,
27: 014003.
doi: 10.11884/HPLPB201527.014003
Abstract:
To investigate the evolutionary characteristics of decay phase of the flash temperature produced by hypervelocity impact on dolomite plate, an experimental measurement system platform was established with two-stage light-gas gun loading system and optical pyrometer measurement system, and the hypervelocity impact experiments were executed in two different velocities (as 1.9, 4.2 km/s)at the same impact angle 45. Theoretical and empirical formula was deduced by shock wave theory. The analysis of the results show that the larger the impact velocity is, the longer the decay time will be and that the theoretical derivation formula is better consistent with the experimental data, and it can be used for estimating such collisions radiation decay phase of the flash temperature.
To investigate the evolutionary characteristics of decay phase of the flash temperature produced by hypervelocity impact on dolomite plate, an experimental measurement system platform was established with two-stage light-gas gun loading system and optical pyrometer measurement system, and the hypervelocity impact experiments were executed in two different velocities (as 1.9, 4.2 km/s)at the same impact angle 45. Theoretical and empirical formula was deduced by shock wave theory. The analysis of the results show that the larger the impact velocity is, the longer the decay time will be and that the theoretical derivation formula is better consistent with the experimental data, and it can be used for estimating such collisions radiation decay phase of the flash temperature.
2015,
27: 014004.
doi: 10.11884/HPLPB201527.014004
Abstract:
Semiconductor detectors made of 4H-SiC material are desirable for applications in harsh environments with high temperature and/or intense radiation. We report the energy resolution and energy linearity of 4H-SiC semiconductor detector using as an alpha particle spectrometer. The leakage current of the 4H-SiC detector is only 14.92 nA/cm2, when a reverse bias of 200 V is applied on it. The energy resolution and energy linearity of 4H-SiC detector are studied using a 226Ra alpha source. The energy resolution of the 4H-SiC detector is 0.61%-0.90% for the 4.8-7.7 MeV alpha particles, which is comparable with the energy resolution results of commercial silicon detectors. The energy linearity of the 4H-SiC detector is very attractive, with the linearly dependent coefficient as good as 0.999 99. This work demonstrates the outstanding energy resolution and energy linearity properties of 4H-SiC semiconductor detectors.
Semiconductor detectors made of 4H-SiC material are desirable for applications in harsh environments with high temperature and/or intense radiation. We report the energy resolution and energy linearity of 4H-SiC semiconductor detector using as an alpha particle spectrometer. The leakage current of the 4H-SiC detector is only 14.92 nA/cm2, when a reverse bias of 200 V is applied on it. The energy resolution and energy linearity of 4H-SiC detector are studied using a 226Ra alpha source. The energy resolution of the 4H-SiC detector is 0.61%-0.90% for the 4.8-7.7 MeV alpha particles, which is comparable with the energy resolution results of commercial silicon detectors. The energy linearity of the 4H-SiC detector is very attractive, with the linearly dependent coefficient as good as 0.999 99. This work demonstrates the outstanding energy resolution and energy linearity properties of 4H-SiC semiconductor detectors.
2015,
27: 014005.
doi: 10.11884/HPLPB201527.014005
Abstract:
The mechanical structure of electronic imaging device was designed by the principle of pinhole imaging in this paper. To ensure the total dose of the probe unit was less than 5 krad in 12 years, the thickness of the shell was about 3 mm copper and the angular resolution of the probe was 20. The detector of anti-proton contamination was designed according to the law of the charged particle energy loss in silicon, the thickness of the detector and the shielding layer was determined. The thickness of the detector is 1000 m and the shielding layer thickness is 10 m (equivalent silicon). By calculation, the design of the electronic imager probe meets the needs of medium-energy electronic detection in space, and lays the foundation for the development of medium-energy electronic imager.
The mechanical structure of electronic imaging device was designed by the principle of pinhole imaging in this paper. To ensure the total dose of the probe unit was less than 5 krad in 12 years, the thickness of the shell was about 3 mm copper and the angular resolution of the probe was 20. The detector of anti-proton contamination was designed according to the law of the charged particle energy loss in silicon, the thickness of the detector and the shielding layer was determined. The thickness of the detector is 1000 m and the shielding layer thickness is 10 m (equivalent silicon). By calculation, the design of the electronic imager probe meets the needs of medium-energy electronic detection in space, and lays the foundation for the development of medium-energy electronic imager.
2015,
27: 014101.
doi: 10.11884/HPLPB201527.014101
Abstract:
Based on simulation and experiment, the way to get three-wavelength antireflective film was researched, A synthesis procedure of SiO2 colloid derived from acid-alkali 2-step catalyzed hydrolysis was disclosed. Two sols were compounded and the three-wavelength antireflective films with transmittances of 351 nm, 527 nm and 1053 nm by over 99.5%, 98% and 98%, were prepared. The properties of the coatings were characterized with TEM, AFM, spectroscopic ellipsometry and spectrophotometer. Three-wavelength antireflective coating on the running performance of high power laser device lifting played a positive role in promoting.
Based on simulation and experiment, the way to get three-wavelength antireflective film was researched, A synthesis procedure of SiO2 colloid derived from acid-alkali 2-step catalyzed hydrolysis was disclosed. Two sols were compounded and the three-wavelength antireflective films with transmittances of 351 nm, 527 nm and 1053 nm by over 99.5%, 98% and 98%, were prepared. The properties of the coatings were characterized with TEM, AFM, spectroscopic ellipsometry and spectrophotometer. Three-wavelength antireflective coating on the running performance of high power laser device lifting played a positive role in promoting.
2015,
27: 014102.
doi: 10.11884/HPLPB201527.014102
Abstract:
Laser devices used in the field of optical-electronics are made of GaAs, InP and so on, which are expensive and hard to be integrated into Si-chip. If a laser device can directly made from silicon, the problems can be solved. A novel strategy for preparing large-area, vertically aligned silicon nanotip arrays at near room temperature by combining silver mirror reaction with metal-catalyzed electroless etching (MCEE) has been developed. It has been demonstrated that the silicon nanotips arrays with a length among 4~7 m and a middle part diameter ranging from 100 to 300 nm have been successfully fabricated on silicon wafers. This method is considerably simple, efficient, nontoxic, controllable and low-cost. Moreover it does not need high temperature, complicated equipments and demanding conditions of environment. At last, the field emission property of the Si nanotip array is primarily tested. The conclusions are as follows: effective electron emission can be obtained by the Si nanotip array; the turn-on field is 2.7 V/m (the current density is 10 A/cm2). The field enhancement factors determined using the F-N curve is 692, the resultant large-area vertically aligned Si nanotips arrays on Si substrate can be expected to be used on field-emitting applications in the future and it will have broad prospects for development.
Laser devices used in the field of optical-electronics are made of GaAs, InP and so on, which are expensive and hard to be integrated into Si-chip. If a laser device can directly made from silicon, the problems can be solved. A novel strategy for preparing large-area, vertically aligned silicon nanotip arrays at near room temperature by combining silver mirror reaction with metal-catalyzed electroless etching (MCEE) has been developed. It has been demonstrated that the silicon nanotips arrays with a length among 4~7 m and a middle part diameter ranging from 100 to 300 nm have been successfully fabricated on silicon wafers. This method is considerably simple, efficient, nontoxic, controllable and low-cost. Moreover it does not need high temperature, complicated equipments and demanding conditions of environment. At last, the field emission property of the Si nanotip array is primarily tested. The conclusions are as follows: effective electron emission can be obtained by the Si nanotip array; the turn-on field is 2.7 V/m (the current density is 10 A/cm2). The field enhancement factors determined using the F-N curve is 692, the resultant large-area vertically aligned Si nanotips arrays on Si substrate can be expected to be used on field-emitting applications in the future and it will have broad prospects for development.
2015,
27: 014103.
doi: 10.11884/HPLPB201527.014103
Abstract:
The property of temperature-frequency drift has an effect on the passband ripples, center frequency and insertion loss of film bulk acoustic resonator (FBAR) filters, reducing the reliability of its electrical application. A temperature-frequency drift simulation of a typical Mo/AlN/Mo 3-layered FBAR is achieved using finite element analysis software ANSYS, and the simulated temperature coefficient of frequency is about －3510－6/℃ within the temperature range ［－50 ℃, 150 ℃］. By adding a SiO2 temperature compensated layer with positive temperature coefficient in the FBAR stacked films structure, the effects of the compensated layer thickness on temperature-frequency drift, resonant frequency and electromechanical coupling are analyzed. The simulated temperature-frequency coefficient of the FBAR stack with a SiO2 temperature compensated layer, which is composed of Mo/AlN/SiO2/Mo multi-layer films, is about 0.87210－6/℃, which shows significantly improved temperature stability compared to that without the temperature compensated layer.
The property of temperature-frequency drift has an effect on the passband ripples, center frequency and insertion loss of film bulk acoustic resonator (FBAR) filters, reducing the reliability of its electrical application. A temperature-frequency drift simulation of a typical Mo/AlN/Mo 3-layered FBAR is achieved using finite element analysis software ANSYS, and the simulated temperature coefficient of frequency is about －3510－6/℃ within the temperature range ［－50 ℃, 150 ℃］. By adding a SiO2 temperature compensated layer with positive temperature coefficient in the FBAR stacked films structure, the effects of the compensated layer thickness on temperature-frequency drift, resonant frequency and electromechanical coupling are analyzed. The simulated temperature-frequency coefficient of the FBAR stack with a SiO2 temperature compensated layer, which is composed of Mo/AlN/SiO2/Mo multi-layer films, is about 0.87210－6/℃, which shows significantly improved temperature stability compared to that without the temperature compensated layer.
2015,
27: 015001.
doi: 10.11884/HPLPB201527.015001
Abstract:
The combination of pulse transformer and sharpening switch is a relatively mature way to generate nanosecond pulse. In this way, a compact high voltage repetitive nanosecond pulse generator (HRNPG) based on Tesla transformer and spark switch is developed in this paper. The pulse generator mainly consists of a repetitive charging module, a Tesla transformer and a sharpening switch. Repetitive charging module is mainly implemented by temporal coordination of two thyristors, Tesla transformer is the core of the pulse generator and main booster module, sharpening switch is a three electrode self-breakdown type gas switch, which is used to sharpen the transformer secondary voltage into nanosecond pulse waveform. Each part of the HRNPG is presented and tested in detail. Applied to a 6 k resistor, the HRNPG prototype is capable of generating a pulse with 100 kV peak voltage and 30 ns rise time at the maximum repetition rate of 500 Hz.
The combination of pulse transformer and sharpening switch is a relatively mature way to generate nanosecond pulse. In this way, a compact high voltage repetitive nanosecond pulse generator (HRNPG) based on Tesla transformer and spark switch is developed in this paper. The pulse generator mainly consists of a repetitive charging module, a Tesla transformer and a sharpening switch. Repetitive charging module is mainly implemented by temporal coordination of two thyristors, Tesla transformer is the core of the pulse generator and main booster module, sharpening switch is a three electrode self-breakdown type gas switch, which is used to sharpen the transformer secondary voltage into nanosecond pulse waveform. Each part of the HRNPG is presented and tested in detail. Applied to a 6 k resistor, the HRNPG prototype is capable of generating a pulse with 100 kV peak voltage and 30 ns rise time at the maximum repetition rate of 500 Hz.
2015,
27: 015002.
doi: 10.11884/HPLPB201527.015002
Abstract:
The flyer plates and the electrodes interact in the emission experiment of high-speed magnetically accelerated flyer plates. The area surrounding the flyer plates and electrodes should be considered in numerical simulation. Hence, a two-dimensional multimedia code is developed on the basis of MDSC2 and numerical simulation of the magnetically accelerated flyer plates is conducted. The results show that the solid density is constantly kept in the free surface of the flyer plates; the speed history of the free surface matches the experimental records by velocity interferometry system for any reflector (VISAR). The middle of the flyer plates keeps a good degree of planarity in the loading procedure of electric currents while the tailing mass at the two ends of the flyer plates is unstable because of the distinguished magnetic strengths between the ends and the middle of the flyer plates.
The flyer plates and the electrodes interact in the emission experiment of high-speed magnetically accelerated flyer plates. The area surrounding the flyer plates and electrodes should be considered in numerical simulation. Hence, a two-dimensional multimedia code is developed on the basis of MDSC2 and numerical simulation of the magnetically accelerated flyer plates is conducted. The results show that the solid density is constantly kept in the free surface of the flyer plates; the speed history of the free surface matches the experimental records by velocity interferometry system for any reflector (VISAR). The middle of the flyer plates keeps a good degree of planarity in the loading procedure of electric currents while the tailing mass at the two ends of the flyer plates is unstable because of the distinguished magnetic strengths between the ends and the middle of the flyer plates.
2015,
27: 015004.
doi: 10.11884/HPLPB201527.015004
Abstract:
This paper designs a high voltage rectangle pulse Marx modulator for gyro-TWT. The output voltage is 70 kV, the output current is 15 A, the frequency could be changed in 2 kHz, the pulse width could be changed in 200 s and the power capacity is up to hundreds kW level. The Marx modulator takes two IGBTs in series as the controlling switches. The FPGA board is used in controlling the switches and protecting and monitoring circuits. The delay compensation circuits are also controlled automatically by FPGA board and make the output pulse flat-top 1%. The prototype simulation and experiments of solid-state Marx modulator have been completed and proved the feasibility of the design. The result is useful to provide a stable and high frequency rectangle pulse, reduce the volume and the maintenance charge and be the foundation of high voltage experiments.
This paper designs a high voltage rectangle pulse Marx modulator for gyro-TWT. The output voltage is 70 kV, the output current is 15 A, the frequency could be changed in 2 kHz, the pulse width could be changed in 200 s and the power capacity is up to hundreds kW level. The Marx modulator takes two IGBTs in series as the controlling switches. The FPGA board is used in controlling the switches and protecting and monitoring circuits. The delay compensation circuits are also controlled automatically by FPGA board and make the output pulse flat-top 1%. The prototype simulation and experiments of solid-state Marx modulator have been completed and proved the feasibility of the design. The result is useful to provide a stable and high frequency rectangle pulse, reduce the volume and the maintenance charge and be the foundation of high voltage experiments.
2015,
27: 015101.
doi: 10.11884/HPLPB201527.015101
Abstract:
A synchronous controller based on FPGA is designed to meet the requirements in the process of controlling injector Ⅱ of accelerator driven sub-critical system (ADS). It provides 4 synchronous pulse signals for some equipments in injector Ⅱ. The controller combines coarse delay based on FPGA and fine delay based on dedicated delay chip to improve the precision of delay and increase the adjustable ranges of period, pulse width and delay. The delay per step is 0.25 ns. Delay, period and pulse width range from 1 s to 2 s. The standard deviation of period jitter is 70 ps. The output signals meet the specified requirements. The program of this controller is easy to operate, and the remote control is stable and reliable.
A synchronous controller based on FPGA is designed to meet the requirements in the process of controlling injector Ⅱ of accelerator driven sub-critical system (ADS). It provides 4 synchronous pulse signals for some equipments in injector Ⅱ. The controller combines coarse delay based on FPGA and fine delay based on dedicated delay chip to improve the precision of delay and increase the adjustable ranges of period, pulse width and delay. The delay per step is 0.25 ns. Delay, period and pulse width range from 1 s to 2 s. The standard deviation of period jitter is 70 ps. The output signals meet the specified requirements. The program of this controller is easy to operate, and the remote control is stable and reliable.
2015,
27: 016001.
doi: 10.11884/HPLPB201527.016001
Abstract:
Z-pinch driven fusion-fission hybrid energy reactor (Z-FFR) is a new energy system, which is helpful to the sustainable development of nuclear energy. It runs in a pulsed mode with a period of 10s, in order to output a mean thermal power of 3000 MWt, a large quantity of energy has to be generated in a pulse. The transient heat transfer and temperature variation of the blanket and first wall in the strong heat shock situation are key issues to the technical feasibility of Z-FFR. In this paper, the temperature variation of blanket and first wall under consecutive heat pulse is analyzed through numerical simulation. Meanwhile, with the aim of exporting electric power stably, a simple method of stabilizing the output power is proposed, and the fluctuation character of the outflow in the main pipe is described. The results show that, the maximum temperatures of all materials are in the safety margin, the thickness of the layer that has a relative high temperature on the surface of the first wall is about 0.5 mm, the output power has a fluctuation of -2.84% to +2.05% relative to the nominal value.
Z-pinch driven fusion-fission hybrid energy reactor (Z-FFR) is a new energy system, which is helpful to the sustainable development of nuclear energy. It runs in a pulsed mode with a period of 10s, in order to output a mean thermal power of 3000 MWt, a large quantity of energy has to be generated in a pulse. The transient heat transfer and temperature variation of the blanket and first wall in the strong heat shock situation are key issues to the technical feasibility of Z-FFR. In this paper, the temperature variation of blanket and first wall under consecutive heat pulse is analyzed through numerical simulation. Meanwhile, with the aim of exporting electric power stably, a simple method of stabilizing the output power is proposed, and the fluctuation character of the outflow in the main pipe is described. The results show that, the maximum temperatures of all materials are in the safety margin, the thickness of the layer that has a relative high temperature on the surface of the first wall is about 0.5 mm, the output power has a fluctuation of -2.84% to +2.05% relative to the nominal value.
2015,
27: 016003.
doi: 10.11884/HPLPB201527.016003
Abstract:
In order to evaluate the importance of fusion-fission hybrid reactor (FFHR) in the future fuel cycle, FFHR symbiotic systems mass balance calculations were carried out. Nuclear energy development scenarios were studied according to nuclear power development status and long-term development planning, and long-term(2030, 2050) development strategy research in China. The growth rate of Chinas economy, population and per capita electricity consumption were taken into account. Chinas installed capacity of nuclear power plants before 2100 was calculated. Four scenarios were assumed as different types of fuel cycle and material balance models were established accordingly. The results show that PWR, FR and FFHR symbiotic model could minimize the demand for natural uranium and save spent fuel disposal cost.
In order to evaluate the importance of fusion-fission hybrid reactor (FFHR) in the future fuel cycle, FFHR symbiotic systems mass balance calculations were carried out. Nuclear energy development scenarios were studied according to nuclear power development status and long-term development planning, and long-term(2030, 2050) development strategy research in China. The growth rate of Chinas economy, population and per capita electricity consumption were taken into account. Chinas installed capacity of nuclear power plants before 2100 was calculated. Four scenarios were assumed as different types of fuel cycle and material balance models were established accordingly. The results show that PWR, FR and FFHR symbiotic model could minimize the demand for natural uranium and save spent fuel disposal cost.
2015,
27: 016004.
doi: 10.11884/HPLPB201527.016004
Abstract:
Based on the multi-element thin-shell model, the parameters of the quasi-spherical wire-arrays are optimized to obtain the final plasma shells with anticipated implosion characters. By optimizing the initial wire-array geometry, we can implode the wire array to the final plasma shell with a suitable aspect ratio, and the aspect ratio is not sensitive to the initial load mass. For a given current shape with a peak current of 1.2 MA and a risetime of 80 ns, the linear density of the wire array with an initial length of 15.4 mm is optimized to maximize the final kinetic energy. Numerical results indicate that the final plasma shell with an equatorial radius of 2 mm and an aspect ratio of 1 obtains maximum kinetic energy 1.5 kJ when the initial linear density takes 150 g/cm. Optimization of the initial linear density is carried out for the current waveforms with different peak values and different risetimes, and the results indicate that the optimized maximum kinetic energy is proportional to the square of the current peak value and the corresponding linear mass is proportional to the square of the current risetime.
Based on the multi-element thin-shell model, the parameters of the quasi-spherical wire-arrays are optimized to obtain the final plasma shells with anticipated implosion characters. By optimizing the initial wire-array geometry, we can implode the wire array to the final plasma shell with a suitable aspect ratio, and the aspect ratio is not sensitive to the initial load mass. For a given current shape with a peak current of 1.2 MA and a risetime of 80 ns, the linear density of the wire array with an initial length of 15.4 mm is optimized to maximize the final kinetic energy. Numerical results indicate that the final plasma shell with an equatorial radius of 2 mm and an aspect ratio of 1 obtains maximum kinetic energy 1.5 kJ when the initial linear density takes 150 g/cm. Optimization of the initial linear density is carried out for the current waveforms with different peak values and different risetimes, and the results indicate that the optimized maximum kinetic energy is proportional to the square of the current peak value and the corresponding linear mass is proportional to the square of the current risetime.
2015,
27: 016005.
doi: 10.11884/HPLPB201527.016005
Abstract:
It is important to understand the tritium properties of tritium breeding materials from the viewpoints of a fusion reactor blanket, the tritium fuel cycle and tritium safety. Out-of-pile tritium release experiments were performed to investigate the effects of heating rate, purge gas composition and platinum catalytic metal on the tritium release behaviors of the lithium aluminate (LiAlO2) ceramic pebbles after neutron-irradiation, and the ESR measuring technique was applied to analyzing the paramagnetic characteristics of irradiation defects. The experimental results show that the bred tritium requires a high temperature region of 750-1000 K to be liberated from LiAlO2 ceramic pebbles corresponding to the slow diffusivity and high desorption activity energy. Catalytic metals and hydrogen in the purge gas can enhance the hydrogen isotope exchange reaction between the tritium on the solid surface and the hydrogen in the purge gas, and accelerate the recovery rate of the molecular tritium (HT). Neutron irradiation can induce F+-center, O--center and O2- center in LiAlO2, and there is a certain relationship between the annihilation behavior of the irradiation defects and the tritium release process.
It is important to understand the tritium properties of tritium breeding materials from the viewpoints of a fusion reactor blanket, the tritium fuel cycle and tritium safety. Out-of-pile tritium release experiments were performed to investigate the effects of heating rate, purge gas composition and platinum catalytic metal on the tritium release behaviors of the lithium aluminate (LiAlO2) ceramic pebbles after neutron-irradiation, and the ESR measuring technique was applied to analyzing the paramagnetic characteristics of irradiation defects. The experimental results show that the bred tritium requires a high temperature region of 750-1000 K to be liberated from LiAlO2 ceramic pebbles corresponding to the slow diffusivity and high desorption activity energy. Catalytic metals and hydrogen in the purge gas can enhance the hydrogen isotope exchange reaction between the tritium on the solid surface and the hydrogen in the purge gas, and accelerate the recovery rate of the molecular tritium (HT). Neutron irradiation can induce F+-center, O--center and O2- center in LiAlO2, and there is a certain relationship between the annihilation behavior of the irradiation defects and the tritium release process.
2015,
27: 016006.
doi: 10.11884/HPLPB201527.016006
Abstract:
Solid breeding blanket is an important type of breeding blanket for fusion reactor or fusion-fission hybrid reactor. It is helpful for the study of tritium sweeping and the optimization of solid breeding blanket structure when one has a good knowledge of the sweep gas pore flow in the pebble bed. In this paper, the packing and porosity distribution in the tritium breeder pebble bed are obtained with the discrete element code PFC3D, and three different sizes of control cells are obtained at randomly distributed positions. With the Boolean operation, the ball volume is subtracted from the cell to get the three-dimensional calculating domain of pore flow. And then this domain is meshed and a computational fluid dynamics (CFD) solver is used to solve the flow equations and get the velocity distribution and pressure drop per length. The results indicate that the velocity magnitude distribution obeys the Gamma distribution. CFD solver is proven to be a reliable tool for sweep gas pore flow when the control cell is properly chosen. This study is helpful for further research of tritium releasing and sweeping.
Solid breeding blanket is an important type of breeding blanket for fusion reactor or fusion-fission hybrid reactor. It is helpful for the study of tritium sweeping and the optimization of solid breeding blanket structure when one has a good knowledge of the sweep gas pore flow in the pebble bed. In this paper, the packing and porosity distribution in the tritium breeder pebble bed are obtained with the discrete element code PFC3D, and three different sizes of control cells are obtained at randomly distributed positions. With the Boolean operation, the ball volume is subtracted from the cell to get the three-dimensional calculating domain of pore flow. And then this domain is meshed and a computational fluid dynamics (CFD) solver is used to solve the flow equations and get the velocity distribution and pressure drop per length. The results indicate that the velocity magnitude distribution obeys the Gamma distribution. CFD solver is proven to be a reliable tool for sweep gas pore flow when the control cell is properly chosen. This study is helpful for further research of tritium releasing and sweeping.
2015,
27: 016007.
doi: 10.11884/HPLPB201527.016007
Abstract:
A new type of engineering-channel water flooding system was proposed to mitigate severe accidents for the subcritical energy cladding of China Academy of Engineering Physics (CAEP)s hybrid reactor. The decay heat of the fuel region can be discharged by injecting cooling water in this system, and the combination of this flooding system with the passive containment cooling system contributes to the establishment of a long-term passive cooling of the fuel region, which prevents the core melting and ensures the integrity of the subcritical energy cladding. Under conservative assumptions, when the fuel temperature reaches 1220 ℃, the engineering-channel water flooding system will start to protect the subcritical energy cladding.
A new type of engineering-channel water flooding system was proposed to mitigate severe accidents for the subcritical energy cladding of China Academy of Engineering Physics (CAEP)s hybrid reactor. The decay heat of the fuel region can be discharged by injecting cooling water in this system, and the combination of this flooding system with the passive containment cooling system contributes to the establishment of a long-term passive cooling of the fuel region, which prevents the core melting and ensures the integrity of the subcritical energy cladding. Under conservative assumptions, when the fuel temperature reaches 1220 ℃, the engineering-channel water flooding system will start to protect the subcritical energy cladding.
2015,
27: 016008.
doi: 10.11884/HPLPB201527.016008
Abstract:
Water desorption behavior of Li4SiO4 ceramic pebbles was studied using temperature programmed desorption (TPD/TDS) method. The experiment results showed that water desorption was mainly followed by four peaks. The peak around 100 ℃ can be attributed to physisorbed water, the peak around 150 ℃ to water chemisorbed on surface oxygen ions through hydrogen bonds, and the peaks around 250 ℃ and 400 ℃ to chemisorbed water in hydroxylated form such as Li－OH and Si－OH. According to the fact that the processes of tritium release and water desorption proceeded almost simultaneously and the release form of tritium was mainly tritiated water (HTO), three mechanisms of tritium release as HTO form were proposed: (1) －OT+H2O－OH+HTO; (2) －OH+－OHH2O, －OT+H2O－OH+HTO; (3) －OT+－OHHTO.
Water desorption behavior of Li4SiO4 ceramic pebbles was studied using temperature programmed desorption (TPD/TDS) method. The experiment results showed that water desorption was mainly followed by four peaks. The peak around 100 ℃ can be attributed to physisorbed water, the peak around 150 ℃ to water chemisorbed on surface oxygen ions through hydrogen bonds, and the peaks around 250 ℃ and 400 ℃ to chemisorbed water in hydroxylated form such as Li－OH and Si－OH. According to the fact that the processes of tritium release and water desorption proceeded almost simultaneously and the release form of tritium was mainly tritiated water (HTO), three mechanisms of tritium release as HTO form were proposed: (1) －OT+H2O－OH+HTO; (2) －OH+－OHH2O, －OT+H2O－OH+HTO; (3) －OT+－OHHTO.
2015,
27: 016009.
doi: 10.11884/HPLPB201527.016009
Abstract:
Tokamak exhaust processing system is an important part of deuterium-tritium fuel cycle system in fusion devices. Its main function is to recover unspent deuterium-tritium fuel from the exhaust gas. Moreover, tritiated gaseous wastes from various other sources are also accepted and decontaminated by the Tokamak exhaust processing system, including the deuterium or helium stream during wall conditioning (glow discharge cleaning), the fluids from the retrieval of tritium from plasma facing components and co-deposits, the tritiated gases yielded during system maintenance, as well as the gases from analytic and auxiliary systems. In this review, the progress in Tokamak exhaust processing technology is summarized, including the compositions of Tokamak exhaust gas and the main methods of Tokamak exhaust processing. The principles and progress of key subsystems technologies in Tokamak exhaust processing system are introduced, such as palladium membrane permeation, palladium membrane reaction and catalytic reaction-palladium membrane permeation, electrolysis reaction, decomposition and oxidization-decomposition reaction. After that the key technologies are analyzed and evaluated. Finally, the main problems and the gap between domestic and foreign development in this field are presented, and necessary research work in the future is proposed.
Tokamak exhaust processing system is an important part of deuterium-tritium fuel cycle system in fusion devices. Its main function is to recover unspent deuterium-tritium fuel from the exhaust gas. Moreover, tritiated gaseous wastes from various other sources are also accepted and decontaminated by the Tokamak exhaust processing system, including the deuterium or helium stream during wall conditioning (glow discharge cleaning), the fluids from the retrieval of tritium from plasma facing components and co-deposits, the tritiated gases yielded during system maintenance, as well as the gases from analytic and auxiliary systems. In this review, the progress in Tokamak exhaust processing technology is summarized, including the compositions of Tokamak exhaust gas and the main methods of Tokamak exhaust processing. The principles and progress of key subsystems technologies in Tokamak exhaust processing system are introduced, such as palladium membrane permeation, palladium membrane reaction and catalytic reaction-palladium membrane permeation, electrolysis reaction, decomposition and oxidization-decomposition reaction. After that the key technologies are analyzed and evaluated. Finally, the main problems and the gap between domestic and foreign development in this field are presented, and necessary research work in the future is proposed.
2015,
27: 016010.
doi: 10.11884/HPLPB201527.016010
Abstract:
Displacement damage and fission gases production due to neutron irradiation damage of the first wall materials W, Fe and Be are analyzed by MC program and irradiation damage program. The results show that hybrid reactor can significantly reduce the requirements on damage of the first wall materials comparing with the pure fusion reactor. Among the materials W, Fe and Be, displacement damage of Be is the minimum for pure fusion reactor and displacement damage and fission gases of W are the minimum for hybrid reactor. From the point of view of neutron irradiation damage, Be is the most suitable for the first wall material of pure fusion reactor, while, W is the most suitable for the first wall material of hybrid reactor among the materials W, Fe and Be.
Displacement damage and fission gases production due to neutron irradiation damage of the first wall materials W, Fe and Be are analyzed by MC program and irradiation damage program. The results show that hybrid reactor can significantly reduce the requirements on damage of the first wall materials comparing with the pure fusion reactor. Among the materials W, Fe and Be, displacement damage of Be is the minimum for pure fusion reactor and displacement damage and fission gases of W are the minimum for hybrid reactor. From the point of view of neutron irradiation damage, Be is the most suitable for the first wall material of pure fusion reactor, while, W is the most suitable for the first wall material of hybrid reactor among the materials W, Fe and Be.
2015,
27: 016011.
doi: 10.11884/HPLPB201527.016011
Abstract:
The Test Blanket Module (TBM) Program has come into the engineering stage with the advance of the ITER project, and the basic TBM design of each ITER member has been fixed. All the TBMs share the same overall objectives, but differ in detailed designs, such as the coolant, tritium breeder, neutron multiplier, plasma facing components material and structural material, etc. The choices of the TBM designs are compared, the advantages and disadvantages of different choices are analyzed.
The Test Blanket Module (TBM) Program has come into the engineering stage with the advance of the ITER project, and the basic TBM design of each ITER member has been fixed. All the TBMs share the same overall objectives, but differ in detailed designs, such as the coolant, tritium breeder, neutron multiplier, plasma facing components material and structural material, etc. The choices of the TBM designs are compared, the advantages and disadvantages of different choices are analyzed.
2015,
27: 016012.
doi: 10.11884/HPLPB201527.016012
Abstract:
A radiation hydrodynamic model of the atmosphere in the fusion chamber of Z-FFR is built by MULTI, and the physical processes in the atmosphere such as the X-ray radiation transport, gas temperature and density evolutions, as well as shock wave generating and propagating, are studied. Radiative temperature and impact pressure on surface of the first wall are subsequently obtained. Static calculations of the X-ray deposition in tungsten and the X-ray attenuation in the Ar atmosphere are accomplished by a Geant4 code. Combining the dynamic and static calculations, preliminary design of the fusion X-ray mitigation is accomplished. The X-ray fluence threshold incident on surface of the first wall is determined to be 0.2 J/cm2, and the initial pressure of the Ar atmosphere is 2000 Pa.
A radiation hydrodynamic model of the atmosphere in the fusion chamber of Z-FFR is built by MULTI, and the physical processes in the atmosphere such as the X-ray radiation transport, gas temperature and density evolutions, as well as shock wave generating and propagating, are studied. Radiative temperature and impact pressure on surface of the first wall are subsequently obtained. Static calculations of the X-ray deposition in tungsten and the X-ray attenuation in the Ar atmosphere are accomplished by a Geant4 code. Combining the dynamic and static calculations, preliminary design of the fusion X-ray mitigation is accomplished. The X-ray fluence threshold incident on surface of the first wall is determined to be 0.2 J/cm2, and the initial pressure of the Ar atmosphere is 2000 Pa.
2015,
27: 016013.
doi: 10.11884/HPLPB201527.016013
Abstract:
The magnet support structure is an important component of the International Thermonuclear Experimental Reactor (ITER). It is the key to carrying out mechanical characteristic analysis of the magnet support structure to ensure the normal operation for the whole reactor. Through the digital analyzing of strength and stiffness for the magnet support structure under all kinds of conditions, this paper gives the stress distribution and deformation of all parts for such structure under its conditions. The analysis results show all parts' maximum stress value for the magnet support structure is below allowable stress and satisfy strength requirement. The deformation for all parts is reasonable, and displacement and instability phenomena do not happen. By digital analysis, it can provide the theory design data and enhance the safety and reliability of the magnet support structure for the International Thermonuclear Experimental Reactor.
The magnet support structure is an important component of the International Thermonuclear Experimental Reactor (ITER). It is the key to carrying out mechanical characteristic analysis of the magnet support structure to ensure the normal operation for the whole reactor. Through the digital analyzing of strength and stiffness for the magnet support structure under all kinds of conditions, this paper gives the stress distribution and deformation of all parts for such structure under its conditions. The analysis results show all parts' maximum stress value for the magnet support structure is below allowable stress and satisfy strength requirement. The deformation for all parts is reasonable, and displacement and instability phenomena do not happen. By digital analysis, it can provide the theory design data and enhance the safety and reliability of the magnet support structure for the International Thermonuclear Experimental Reactor.
2015,
27: 016014.
doi: 10.11884/HPLPB201527.016014
Abstract:
This paper introduces the structure design of subcritical blanket driven by ITER in detail. Along the toroidal 360 degree, the whole subcritical blanket is divided into thirty six petals. Furthermore, based on the interface of plasma chamber, each single blanket petal is divided into inner and outer parts, every part is made up of the first wall structure, supporting structure, fuel zone structure, tritium producing zone structure and zirconium cladding structure. For distinguishing the petal from the present small module blanket structure of ITER device, the inner and outer blankets are designed as a type of whole embedding structure to reduce the pipe connecting plug quantities of a large quantity of embedding coolant pressure pipes in fission fuel zone, shorten the period of changing fuel and reduce the cost. At the same time, considering the confinement of ITER device self-structure space for the subcritical blanket, a sort of converging pipe structure which can satisfy the requirements of thermal-fluid and realize project welding assembly for blanket is put forward. Finally, using software Pro/e, the blankets three dimensional CAD drawing is established in order to output the finite element computation model for mechanical analysis.
This paper introduces the structure design of subcritical blanket driven by ITER in detail. Along the toroidal 360 degree, the whole subcritical blanket is divided into thirty six petals. Furthermore, based on the interface of plasma chamber, each single blanket petal is divided into inner and outer parts, every part is made up of the first wall structure, supporting structure, fuel zone structure, tritium producing zone structure and zirconium cladding structure. For distinguishing the petal from the present small module blanket structure of ITER device, the inner and outer blankets are designed as a type of whole embedding structure to reduce the pipe connecting plug quantities of a large quantity of embedding coolant pressure pipes in fission fuel zone, shorten the period of changing fuel and reduce the cost. At the same time, considering the confinement of ITER device self-structure space for the subcritical blanket, a sort of converging pipe structure which can satisfy the requirements of thermal-fluid and realize project welding assembly for blanket is put forward. Finally, using software Pro/e, the blankets three dimensional CAD drawing is established in order to output the finite element computation model for mechanical analysis.
2015,
27: 016015.
doi: 10.11884/HPLPB201527.016015
Abstract:
Based on the current ITER design, there will be 12% inert gases in the off-gases from the torus collected in the cryopumps. The concentration polarization existing in the Pd membraneseparation processes could seriously affect the processes. In this work, the concentration polarization phenomenon in a porous ceramic supported Pd-based membrane for the separation of H2/He has been studied. A polarization coefficient was defined to describe the extent of the concentration polarization phenomenon, the effect of operation parameters such as operation pressure, upstream He molar fraction, and feed gas flow rate on the coefficient were investigated. The results show that the degree of inhibition by concentration polarization in hydrogen permeation decreases with increasing feed gas flow rate, whereas increases with rising He molar fraction and upstream total pressure.
Based on the current ITER design, there will be 12% inert gases in the off-gases from the torus collected in the cryopumps. The concentration polarization existing in the Pd membraneseparation processes could seriously affect the processes. In this work, the concentration polarization phenomenon in a porous ceramic supported Pd-based membrane for the separation of H2/He has been studied. A polarization coefficient was defined to describe the extent of the concentration polarization phenomenon, the effect of operation parameters such as operation pressure, upstream He molar fraction, and feed gas flow rate on the coefficient were investigated. The results show that the degree of inhibition by concentration polarization in hydrogen permeation decreases with increasing feed gas flow rate, whereas increases with rising He molar fraction and upstream total pressure.
2015,
27: 016016.
doi: 10.11884/HPLPB201527.016016
Abstract:
The inorganic proton conductor BaZrO3 was prepared by high solid-state reaction. The effect of flux on the synthesis temperature and microstructure of the material was investigated. The BaZrO3 single phase can be synthesized at 1500 ℃ for 8 h by adding LiF and Li2CO3 as flux. The crystallinity of the sample which used LiF as flux was much higher than that of the sample which used Li2CO3 as flux. The Rietveld-XRD data showed that the sample had good crystallinity. The band gap of the sample was 3.236 eV. The micro-morphology was changed by adding the flux. The sample used LiF as flux had smaller particle size, fewer aggregations and good dispersion. The small particles were separated out at the grain boundary, when the mass fraction of the flux was more than 8%. These small particles had potential to increase the proton conductivity.
The inorganic proton conductor BaZrO3 was prepared by high solid-state reaction. The effect of flux on the synthesis temperature and microstructure of the material was investigated. The BaZrO3 single phase can be synthesized at 1500 ℃ for 8 h by adding LiF and Li2CO3 as flux. The crystallinity of the sample which used LiF as flux was much higher than that of the sample which used Li2CO3 as flux. The Rietveld-XRD data showed that the sample had good crystallinity. The band gap of the sample was 3.236 eV. The micro-morphology was changed by adding the flux. The sample used LiF as flux had smaller particle size, fewer aggregations and good dispersion. The small particles were separated out at the grain boundary, when the mass fraction of the flux was more than 8%. These small particles had potential to increase the proton conductivity.
2015,
27: 016017.
doi: 10.11884/HPLPB201527.016017
Abstract:
According to the pressure tube supercritical water reactor (PT-SCWR) new 62-element design, the power density and the fuel temperature, coolant density/temperature are coupled. Neutron physics analysis code (WIMS-AECL) and sub-channel analysis code (ATHAS) are used to optimize the design. The results show that the coupling method is effective. The results indicate that the maximum cladding surface temperature of the bundle and the coolant outlet temperature are lower than the design limits. So the scheme meets the design objectives. We can adjust the fuel enrichment from 5% to 5.5% and 4.6%, adjust the fuel assembly pitch circle of the inner bundle from 5.30 cm to 5.175 cm to obtain a uniformity temperature distribution. By comparing the moderator temperature coefficient and void coefficient under different pitch, we obtained an optimum pitch of 21cm.
According to the pressure tube supercritical water reactor (PT-SCWR) new 62-element design, the power density and the fuel temperature, coolant density/temperature are coupled. Neutron physics analysis code (WIMS-AECL) and sub-channel analysis code (ATHAS) are used to optimize the design. The results show that the coupling method is effective. The results indicate that the maximum cladding surface temperature of the bundle and the coolant outlet temperature are lower than the design limits. So the scheme meets the design objectives. We can adjust the fuel enrichment from 5% to 5.5% and 4.6%, adjust the fuel assembly pitch circle of the inner bundle from 5.30 cm to 5.175 cm to obtain a uniformity temperature distribution. By comparing the moderator temperature coefficient and void coefficient under different pitch, we obtained an optimum pitch of 21cm.
2015,
27: 019001.
doi: 10.11884/HPLPB201527.019001
Abstract:
Precise frequency calibration is critical to maintain the accuracy of wind retrieval from a Rayleigh Doppler wind lidar. The frequency of the laser is locked at the cross-point of the transmission functions of double-edge channels by tuning the cavity length of the Fabry-Perot interferometer (FPI) continuously. However, the non-linearity due to hysteresis in the PZT will introduce systematic errors. To overcome this drawback, a new method of frequency calibration and frequency locking is proposed and demonstrated. If the relative frequency drift between the laser and the FPI is less than 100 MHz, the frequency deviation is monitored and then compensated in the data processing. Once the relative frequency drift is large than 100 MHz, the frequency locking point is reset. In their procedure, the cavity length is shrunk in two steps: first tune the voltage under the preset point, then increase the voltage along the rising edge of the hysteresis loop gradually until the frequency locking is achieved again. In the comparison experiments, the new method is adopted. The maximum (average) wind speed deviation between the results from Doppler lidar and radiosonde is 6.22 m/s (1.12 m/s) in the altitude from 15 km to 30 km.
Precise frequency calibration is critical to maintain the accuracy of wind retrieval from a Rayleigh Doppler wind lidar. The frequency of the laser is locked at the cross-point of the transmission functions of double-edge channels by tuning the cavity length of the Fabry-Perot interferometer (FPI) continuously. However, the non-linearity due to hysteresis in the PZT will introduce systematic errors. To overcome this drawback, a new method of frequency calibration and frequency locking is proposed and demonstrated. If the relative frequency drift between the laser and the FPI is less than 100 MHz, the frequency deviation is monitored and then compensated in the data processing. Once the relative frequency drift is large than 100 MHz, the frequency locking point is reset. In their procedure, the cavity length is shrunk in two steps: first tune the voltage under the preset point, then increase the voltage along the rising edge of the hysteresis loop gradually until the frequency locking is achieved again. In the comparison experiments, the new method is adopted. The maximum (average) wind speed deviation between the results from Doppler lidar and radiosonde is 6.22 m/s (1.12 m/s) in the altitude from 15 km to 30 km.
2015,
27: 015003.
doi: 10.11884/HPLPB201527.015003
Abstract:
To verify the feasibility of a pulse generator based on electromagnetic induction, a test model of the small pulse generator was designed. The phase transition of magnetic core was analyzed and the magnetic field was calculated. The equivalent circuit model of the generator was established to get the relationship between electric components. The entire outer diameter of the generator is about 70 mm, and the length is about 85 mm. The diameter of the magnetic core in the generator is 25 mm, and the length is 25 mm. The thickness of the permanent magnet which provides the initial magnetic field is 10 mm. A pulse voltage with a peak value of 784.5 V obtained in the experiment is in agreement with the value of the pulse voltage by calculation.
To verify the feasibility of a pulse generator based on electromagnetic induction, a test model of the small pulse generator was designed. The phase transition of magnetic core was analyzed and the magnetic field was calculated. The equivalent circuit model of the generator was established to get the relationship between electric components. The entire outer diameter of the generator is about 70 mm, and the length is about 85 mm. The diameter of the magnetic core in the generator is 25 mm, and the length is 25 mm. The thickness of the permanent magnet which provides the initial magnetic field is 10 mm. A pulse voltage with a peak value of 784.5 V obtained in the experiment is in agreement with the value of the pulse voltage by calculation.
2015,
27: 016002.
doi: 10.11884/HPLPB201527.016002
Abstract:
As a competitive energy system, Z-pinch driven fusion-fission hybrid reactor (Z-FFR) is developed in concept study stage, while blanket research is one important part. In this paper the Z-FFR blanket design model is set up, and influence factor, neutron balance, flux, power density and burnup of the model are analyzed. The average energy multiplication factor (M), tritium breeding ratio (TBR) and fuel breeding ratio (F/B) for 50 years are 14.91, 1.294 and 5.140, respectively, which can meet the design requirements. Considering pulse characteristic of fusion source, the transient neutronics properties are also studied. In fuel zone neutron, there are three parts of pulse: fusion neutron pulse, prompt fission neutron pulse and delayed fission neutron pulse. Most of the energy in fuel zone is deposited in 0.01 s. The complete neutron parameters of Z-FFR blanket are given, which provide the foundation for the concept study.
As a competitive energy system, Z-pinch driven fusion-fission hybrid reactor (Z-FFR) is developed in concept study stage, while blanket research is one important part. In this paper the Z-FFR blanket design model is set up, and influence factor, neutron balance, flux, power density and burnup of the model are analyzed. The average energy multiplication factor (M), tritium breeding ratio (TBR) and fuel breeding ratio (F/B) for 50 years are 14.91, 1.294 and 5.140, respectively, which can meet the design requirements. Considering pulse characteristic of fusion source, the transient neutronics properties are also studied. In fuel zone neutron, there are three parts of pulse: fusion neutron pulse, prompt fission neutron pulse and delayed fission neutron pulse. Most of the energy in fuel zone is deposited in 0.01 s. The complete neutron parameters of Z-FFR blanket are given, which provide the foundation for the concept study.
