Email alert
RSS2012 Vol. 24, No. 12
Recommend Articles
Display Method:
2012,
24: 2773-2777.
doi: 10.3788/HPLPB20122412.2773
Abstract:
In order to have an investigation for the scattering light produced by laser plasma interaction at Shenguang Ⅲ laser facility, a new full-aperture backscatter light diagnostic system was developed. According to the properties of Brillouin scattering and Raman scattering, the system gives multiple light splitting and purification, and avoids the effect of stray light. Thus the system has a calibration for the damping factor by using a tailor-made full-aperture laser. The results show that the new full-aperture backscatter light diagnostic system can work stably, and can significantly reduce the effects of stray light. So compared with the original system, the measured data of this system are more reliable.
In order to have an investigation for the scattering light produced by laser plasma interaction at Shenguang Ⅲ laser facility, a new full-aperture backscatter light diagnostic system was developed. According to the properties of Brillouin scattering and Raman scattering, the system gives multiple light splitting and purification, and avoids the effect of stray light. Thus the system has a calibration for the damping factor by using a tailor-made full-aperture laser. The results show that the new full-aperture backscatter light diagnostic system can work stably, and can significantly reduce the effects of stray light. So compared with the original system, the measured data of this system are more reliable.
2012,
24: 2778-2782.
doi: 10.3788/HPLPB20122412.2778
Abstract:
Atmospheric refractivity significantly influences optoelectronic measuring accuracy and laser propagation, so an accurate knowledge of the refractivity profile is important. In this paper, calculations of the refractive index using atmospheric parameters for the near and middle infrared are carried out, and then the refractivity profiles of the Gobi zone in Xinjiang are obtained from the sounding data for the latest few years. The statistical distributions of the refractive index in every season for wavelengths of 4 m and 1.32 m are discussed in detail, and the three-parameter exponential mode is proposed to describe the mean refractivity profile. A three-parameter exponential profile for wavelengths of 4 m and 1.32 m in every season is given by nonlinear fitting. The statistical refractive profile is used to correct the refractive error of the data obtained from the optoelectronic equipments in real-time. This correction result is compared with the post correction result using the measured profile, with the difference of them less than 5.
Atmospheric refractivity significantly influences optoelectronic measuring accuracy and laser propagation, so an accurate knowledge of the refractivity profile is important. In this paper, calculations of the refractive index using atmospheric parameters for the near and middle infrared are carried out, and then the refractivity profiles of the Gobi zone in Xinjiang are obtained from the sounding data for the latest few years. The statistical distributions of the refractive index in every season for wavelengths of 4 m and 1.32 m are discussed in detail, and the three-parameter exponential mode is proposed to describe the mean refractivity profile. A three-parameter exponential profile for wavelengths of 4 m and 1.32 m in every season is given by nonlinear fitting. The statistical refractive profile is used to correct the refractive error of the data obtained from the optoelectronic equipments in real-time. This correction result is compared with the post correction result using the measured profile, with the difference of them less than 5.
2012,
24: 2783-2786.
doi: 10.3788/HPLPB20122412.2783
Abstract:
The graphene-oxide-based passively Q-switched erbium-doped fiber laser is first reported. The laser adopts ring cavity configuration, and the Q-switcher is the self-made graphene oxide saturable absorber mirror. Stable Q-switched pulses with the frequency of 68~124 kHz and pulse width of 0.47~1.6 s are output at 80~505 mW incident pump power. Limited by the pump power, the maximum output power is 10 mW, corresponding to the single pulse energy of 80.6 nJ. This kind of new Q-switched fiber laser with graphene oxide as the saturable absorber will have great applications, due to its advantages of low price, simple design and high stability.
The graphene-oxide-based passively Q-switched erbium-doped fiber laser is first reported. The laser adopts ring cavity configuration, and the Q-switcher is the self-made graphene oxide saturable absorber mirror. Stable Q-switched pulses with the frequency of 68~124 kHz and pulse width of 0.47~1.6 s are output at 80~505 mW incident pump power. Limited by the pump power, the maximum output power is 10 mW, corresponding to the single pulse energy of 80.6 nJ. This kind of new Q-switched fiber laser with graphene oxide as the saturable absorber will have great applications, due to its advantages of low price, simple design and high stability.
2012,
24: 2787-2790.
doi: 10.3788/HPLPB20122412.2787
Abstract:
The dynamic process of intense 50 fs laser ablation of silicon is investigated by the way of ultrafast time-resolved shadowgraphy. The formation and development processes of plasma and shock wave are recorded, and it is known that the process of material ejection is discontinuous. The process can be divided obviously into two processes, which shows that at different stages there are different mechanism leading the interaction of laser and material. In the shadowgraph of 19 ns time delay, it is found that the shock wave is distorted from the hemispherical shape.
The dynamic process of intense 50 fs laser ablation of silicon is investigated by the way of ultrafast time-resolved shadowgraphy. The formation and development processes of plasma and shock wave are recorded, and it is known that the process of material ejection is discontinuous. The process can be divided obviously into two processes, which shows that at different stages there are different mechanism leading the interaction of laser and material. In the shadowgraph of 19 ns time delay, it is found that the shock wave is distorted from the hemispherical shape.
2012,
24: 2791-2796.
doi: 10.3788/HPLPB20122412.2791
Abstract:
The coherently coupled nonlinear Schrdinger (NLS) equation for laser propagating in birefringent fiber with parametric amplification and Raman scattering has been utilized. Considering higher-order dispersive, the gain spectra are studied under coaction of Raman scattering and parametric amplification when the pump wave polarization is oriented at 45 between the axes by quoting Lorentzian model of Raman gain spectra in high-birefringence fiber. The results show that the gain spectra are influenced by high-order dispersion under different input parameters (the input power, group velocity mismatch) in the anomalous(or normal) dispersion regime. The structure and intensity as well as width of gain spectra will change. The influence of high-order dispersion on the gain spectra cannot been neglected. The T-frequency pulses can been extracted when gain spectra are away from center frequency in high group-velocity mismatching zone.
The coherently coupled nonlinear Schrdinger (NLS) equation for laser propagating in birefringent fiber with parametric amplification and Raman scattering has been utilized. Considering higher-order dispersive, the gain spectra are studied under coaction of Raman scattering and parametric amplification when the pump wave polarization is oriented at 45 between the axes by quoting Lorentzian model of Raman gain spectra in high-birefringence fiber. The results show that the gain spectra are influenced by high-order dispersion under different input parameters (the input power, group velocity mismatch) in the anomalous(or normal) dispersion regime. The structure and intensity as well as width of gain spectra will change. The influence of high-order dispersion on the gain spectra cannot been neglected. The T-frequency pulses can been extracted when gain spectra are away from center frequency in high group-velocity mismatching zone.
2012,
24: 2797-2801.
doi: 10.3788/HPLPB20122412.2797
Abstract:
A kind of compact short electromagnetic pulse sensor with short dipole is studied in this paper. The basic principle of the sensor and the relationship between geometry and electromagnetic parameters such as capacitance and equivalent area are introduced. A series of sensors is designed and fabricated for the measurement of short pulses with different widths. Experiments on such sensors are carried out in the ultra-wideband TEM cell produced by the mono-conical antenna. The waveform fidelity and the equivalent area are surveyed in the experiments. The numerical analysis and experimental results show that the sensor could receive and reconstruct short pulses very well and the measured value of the equivalent area coincides with the theoretical prediction. The small sensor studied in this paper is a good choice for the miniaturization of antenna measurements for ultra-wideband electromagnetic pulses.
A kind of compact short electromagnetic pulse sensor with short dipole is studied in this paper. The basic principle of the sensor and the relationship between geometry and electromagnetic parameters such as capacitance and equivalent area are introduced. A series of sensors is designed and fabricated for the measurement of short pulses with different widths. Experiments on such sensors are carried out in the ultra-wideband TEM cell produced by the mono-conical antenna. The waveform fidelity and the equivalent area are surveyed in the experiments. The numerical analysis and experimental results show that the sensor could receive and reconstruct short pulses very well and the measured value of the equivalent area coincides with the theoretical prediction. The small sensor studied in this paper is a good choice for the miniaturization of antenna measurements for ultra-wideband electromagnetic pulses.
2012,
24: 2802-2806.
doi: 10.3788/HPLPB20122412.2802
Abstract:
Smoothed particle hydrodynamics (SPH) is a typical meshless particle method. However, the heat flux boundary of laser radiation in SPH method is a big problem which dues to the difficulty of determining particles which receive the lasers energy in a time-step. In this paper, the problem is solved by the difference method, and a three-dimensional program LAMP (laser ablation material program) is compiled with FORTRAN language to numerical simulate the interaction between 5.0109 W/cm2 continuous wave laser and a columnar aluminum target. The boundary particles which receive the lasers energy are accurately determined, and temperature distributions at different time in the target are obtained.
Smoothed particle hydrodynamics (SPH) is a typical meshless particle method. However, the heat flux boundary of laser radiation in SPH method is a big problem which dues to the difficulty of determining particles which receive the lasers energy in a time-step. In this paper, the problem is solved by the difference method, and a three-dimensional program LAMP (laser ablation material program) is compiled with FORTRAN language to numerical simulate the interaction between 5.0109 W/cm2 continuous wave laser and a columnar aluminum target. The boundary particles which receive the lasers energy are accurately determined, and temperature distributions at different time in the target are obtained.
2012,
24: 2807-2810.
doi: 10.3788/HPLPB20122412.2807
Abstract:
A graphene-based Q-switcher is fabricated by the optical deposition of graphene in a fiber ferrule. The passively Q-switched Er-doped fiber ring laser with the Q-switcher as saturable absorber is made, which produces stable Q-switched pulse with pulse width of 8 s and maximum output average power 162.3 W. The repetition rate can be tuned from 5.1 kHz to 14.2 kHz with the increase of the pump power. The central wavelength can be tuned from 1556 nm to 1558 nm by rotating the polarization controller.
A graphene-based Q-switcher is fabricated by the optical deposition of graphene in a fiber ferrule. The passively Q-switched Er-doped fiber ring laser with the Q-switcher as saturable absorber is made, which produces stable Q-switched pulse with pulse width of 8 s and maximum output average power 162.3 W. The repetition rate can be tuned from 5.1 kHz to 14.2 kHz with the increase of the pump power. The central wavelength can be tuned from 1556 nm to 1558 nm by rotating the polarization controller.
2012,
24: 2811-2816.
doi: 10.3788/HPLPB20122412.2811
Abstract:
During propagating in Nd-glass amplifiers, the spectra of the broadband laser pulses are modulated due to gain narrowing and gain saturation effects, resulting in loss of sidebands and unbalance of the spectra, and further leading to the temporal intensity modulation. The amplitude modulations (AMs) have been numerically simulated for different broadband laser sources. The effects of the gain bandwidth, the laser bandwidth, as well as the deviation of central wavelength between the laser source and amplifier on the AMs have been analyzed. Results indicate that all of the different broadband laser sources discussed in this paper exhibit more or less AMs, and the temporal intensity modulation of stacked chirped pulses is smaller than that of sinusoidally frequency-modulated pulses.
During propagating in Nd-glass amplifiers, the spectra of the broadband laser pulses are modulated due to gain narrowing and gain saturation effects, resulting in loss of sidebands and unbalance of the spectra, and further leading to the temporal intensity modulation. The amplitude modulations (AMs) have been numerically simulated for different broadband laser sources. The effects of the gain bandwidth, the laser bandwidth, as well as the deviation of central wavelength between the laser source and amplifier on the AMs have been analyzed. Results indicate that all of the different broadband laser sources discussed in this paper exhibit more or less AMs, and the temporal intensity modulation of stacked chirped pulses is smaller than that of sinusoidally frequency-modulated pulses.
2012,
24: 2817-2821.
doi: 10.3788/HPLPB20122412.2817
Abstract:
Aim at solving the problem that the high computational complexity of level set methods excludes themselves from many real-time applications, an improved image segmentation method based on the fast level set algorithm is proposed in this paper. The proposed algorithm adopts an improved fast level set with a single list to realize the curve evolution, and it uses the binary fitting terms of the C-V model to design the speed function of curve evolution, preserving the global optimization characteristic of the C-V model. In addition, a termination criterion based on the number changing of contour points in the single list is proposed to ensure that the evolving curve can automatically stop on the true boundaries of objects. Experimental results show that the proposed algorithm can significantly improve the segmentation speed and can efficiently segment the noisy images.
Aim at solving the problem that the high computational complexity of level set methods excludes themselves from many real-time applications, an improved image segmentation method based on the fast level set algorithm is proposed in this paper. The proposed algorithm adopts an improved fast level set with a single list to realize the curve evolution, and it uses the binary fitting terms of the C-V model to design the speed function of curve evolution, preserving the global optimization characteristic of the C-V model. In addition, a termination criterion based on the number changing of contour points in the single list is proposed to ensure that the evolving curve can automatically stop on the true boundaries of objects. Experimental results show that the proposed algorithm can significantly improve the segmentation speed and can efficiently segment the noisy images.
2012,
24: 2822-2826.
doi: 10.3788/HPLPB20122412.2822
Abstract:
An underwater detector was designed based on the technology of laser-induced sound by underwater explosion. The mechanism of underwater explosion sound by laser was studied, and then the detecting experimental system was built. The experimental results show that the laser-induced sound signal might be produced by high-power pulse laser breakdown under water, and that the spherical laser-induced sound signal can be changed into the plane wave signal by the acoustic reflector inside the detector. The laser-induced sound signals from the detector are found to have the characteristics of narrow-beam direction, high range resolution and long detection range by numerical calculation, which meet the requirement of underwater detection.
An underwater detector was designed based on the technology of laser-induced sound by underwater explosion. The mechanism of underwater explosion sound by laser was studied, and then the detecting experimental system was built. The experimental results show that the laser-induced sound signal might be produced by high-power pulse laser breakdown under water, and that the spherical laser-induced sound signal can be changed into the plane wave signal by the acoustic reflector inside the detector. The laser-induced sound signals from the detector are found to have the characteristics of narrow-beam direction, high range resolution and long detection range by numerical calculation, which meet the requirement of underwater detection.
2012,
24: 2827-2830.
doi: 10.3788/HPLPB20122412.2827
Abstract:
The reflectivity characteristic of 30CrMnSiA steel under continuous-wave laser repeated irradiation is explored, by using the double-beam reflectivity measurement device. The reflectivity under only once laser irradiation is compared with that in the process of laser irradiation, cooling, laser re-irradiation. It is found that the reflectivity under the laser re-irradiation is basically the same with the reflectivity corresponding to the maximum temperature in the process of the first laser irradiation, and begins to change only when the temperature exceeds the maximum temperature, and the variation trend of the reflectivity under the laser re-irradiation is the same with that under only once laser irradiation. It indicates that the reflectivity on the surface is related to the maximum surface temperature. The further study results show that the maximum surface temperature could affect the surface oxide layer and the oxide layer thickness does not change in the cooling and re-irradiation process.
The reflectivity characteristic of 30CrMnSiA steel under continuous-wave laser repeated irradiation is explored, by using the double-beam reflectivity measurement device. The reflectivity under only once laser irradiation is compared with that in the process of laser irradiation, cooling, laser re-irradiation. It is found that the reflectivity under the laser re-irradiation is basically the same with the reflectivity corresponding to the maximum temperature in the process of the first laser irradiation, and begins to change only when the temperature exceeds the maximum temperature, and the variation trend of the reflectivity under the laser re-irradiation is the same with that under only once laser irradiation. It indicates that the reflectivity on the surface is related to the maximum surface temperature. The further study results show that the maximum surface temperature could affect the surface oxide layer and the oxide layer thickness does not change in the cooling and re-irradiation process.
2012,
24: 2831-2836.
doi: 10.3788/HPLPB20122412.2831
Abstract:
According to the requirement of implosions at the Shengguang-Ⅲ facility and its prototype, the design of a magnetic proton recoil spectrometer was illuminated, and it was simulated by the Monte-Carlo code Geant4. Neutron spectra in the range of 6~30 MeV can be measured by the spectrometer, and it is sensitive when neutron yield is larger than 1012. The whole neutron spectrum produced in implosions can be measured with the spectrometer. Simulation results show that the detection efficiency of the spectrometer is bigger than 10-11 in measuring 14 MeV neutrons with an energy resolution of about 1%, and the signal-to-background ratio of the spectrometer is larger than 10. The spectrometer can be used to diagnose ion temperature of DT fuel at the Shengguang-Ⅲ facility prototype.
According to the requirement of implosions at the Shengguang-Ⅲ facility and its prototype, the design of a magnetic proton recoil spectrometer was illuminated, and it was simulated by the Monte-Carlo code Geant4. Neutron spectra in the range of 6~30 MeV can be measured by the spectrometer, and it is sensitive when neutron yield is larger than 1012. The whole neutron spectrum produced in implosions can be measured with the spectrometer. Simulation results show that the detection efficiency of the spectrometer is bigger than 10-11 in measuring 14 MeV neutrons with an energy resolution of about 1%, and the signal-to-background ratio of the spectrometer is larger than 10. The spectrometer can be used to diagnose ion temperature of DT fuel at the Shengguang-Ⅲ facility prototype.
2012,
24: 2837-2840.
doi: 10.3788/HPLPB20122412.2837
Abstract:
For studing the yield and spatial distributions of protons produced in the interaction of femtosecond laser with plasmas, protons behavior at the normal direction of the rear surface of the target irradiated by ultra-intensity pulse laser irradiated solid targets was explored on SILEX-I laser facility. The yield and spatial distributions of the protons with different target thicknesses were recorded by radiochromic film (RCF) HD810. The results show that the optics density (OD) is closely correlated with the protons flux, OD values increase with the increasing of proton beam flux;For fixed thickness of C8H8 layer, the proton beam flux and yield of protons and OD of RCF decrease with the increasing Cu layer thickness;for the same thickness of targets, the OD and yield of protons decrease with the decreases of laser intensity;And the corresponding spatial profile of proton beam shows ring-, filament-, and disc-like distribution. The size of the distribution is independent of laser focus.
For studing the yield and spatial distributions of protons produced in the interaction of femtosecond laser with plasmas, protons behavior at the normal direction of the rear surface of the target irradiated by ultra-intensity pulse laser irradiated solid targets was explored on SILEX-I laser facility. The yield and spatial distributions of the protons with different target thicknesses were recorded by radiochromic film (RCF) HD810. The results show that the optics density (OD) is closely correlated with the protons flux, OD values increase with the increasing of proton beam flux;For fixed thickness of C8H8 layer, the proton beam flux and yield of protons and OD of RCF decrease with the increasing Cu layer thickness;for the same thickness of targets, the OD and yield of protons decrease with the decreases of laser intensity;And the corresponding spatial profile of proton beam shows ring-, filament-, and disc-like distribution. The size of the distribution is independent of laser focus.
2012,
24: 2841-2847.
doi: 10.3788/HPLPB20122412.2841
Abstract:
The one-dimensional fluid mechanics model of plasma was employed to investigate capacitively coupled discharge in hybrid gas of Helium-oxygen. The relationship between applied voltage and discharge current with gaps of 1.6 mm, 2.4 mm, 3.2 mm was discussed and compared with the experimental data. The simulation results are in good agreement with the experimental voltage versus current curve. It is found that the charge-to-mass ratio of positive ions has certain effect on ions distribution in the process of the capacitively coupled high-pressure glow discharge. The distribution of the positive ion and negative ion of oxygen reaches its peak values at two terminal areas of the main plasma region.
The one-dimensional fluid mechanics model of plasma was employed to investigate capacitively coupled discharge in hybrid gas of Helium-oxygen. The relationship between applied voltage and discharge current with gaps of 1.6 mm, 2.4 mm, 3.2 mm was discussed and compared with the experimental data. The simulation results are in good agreement with the experimental voltage versus current curve. It is found that the charge-to-mass ratio of positive ions has certain effect on ions distribution in the process of the capacitively coupled high-pressure glow discharge. The distribution of the positive ion and negative ion of oxygen reaches its peak values at two terminal areas of the main plasma region.
2012,
24: 2848-2852.
doi: 10.3788/HPLPB20122412.2848
Abstract:
Nitrogen-doped carbon aerogels (NCAs) were synthesized from melamine, resorcinol and formaldehyde by sol-gel, supercritical drying and high-temperature carbonization process. The structure properties and function of the NCAs were characterized by means of XPS, SEM and nitrogen adsorption, showing that the nitrogen was successfully doped into carbon aerogels. Meanwhile, the N-doping content and the microstructures of the NCAs distinctly depend on the amount of melamine. Besides, the electrochemical performances of the NCAs were tested by galvanostatic charge-discharge and cyclic voltammetry in 6 mol/L KOH solution, and the results indicate that their electrochemical performances are greatly improved after N-doping with the highest specific capacitance reaching 176 Fg-1.
Nitrogen-doped carbon aerogels (NCAs) were synthesized from melamine, resorcinol and formaldehyde by sol-gel, supercritical drying and high-temperature carbonization process. The structure properties and function of the NCAs were characterized by means of XPS, SEM and nitrogen adsorption, showing that the nitrogen was successfully doped into carbon aerogels. Meanwhile, the N-doping content and the microstructures of the NCAs distinctly depend on the amount of melamine. Besides, the electrochemical performances of the NCAs were tested by galvanostatic charge-discharge and cyclic voltammetry in 6 mol/L KOH solution, and the results indicate that their electrochemical performances are greatly improved after N-doping with the highest specific capacitance reaching 176 Fg-1.
2012,
24: 2853-2857.
doi: 10.3788/HPLPB20122412.2853
Abstract:
Development of the near backscatter light diagnostic system is important to measuring the stimulated Brillouin and stimulated Raman scatter so that the near backscatter light fraction of the ICF drive laser will be determined. Based on SG-Ⅲ prototype laser facility, a near backscatter light diagnostic system with an ellipsoidal mirror and other relay optics as core elements is designed and implemented on the facility. The whole system is well held and modulated by a portable configuration. Both the optical and mechanical design items are introduced in this paper. According to the experiment results, the system is credible and effective.
Development of the near backscatter light diagnostic system is important to measuring the stimulated Brillouin and stimulated Raman scatter so that the near backscatter light fraction of the ICF drive laser will be determined. Based on SG-Ⅲ prototype laser facility, a near backscatter light diagnostic system with an ellipsoidal mirror and other relay optics as core elements is designed and implemented on the facility. The whole system is well held and modulated by a portable configuration. Both the optical and mechanical design items are introduced in this paper. According to the experiment results, the system is credible and effective.
2012,
24: 2858-2864.
doi: 10.3788/HPLPB20122412.2858
Abstract:
This paper presents the simulation study of a C-band 50 MW klystron with disc-loaded waveguide traveling wave output structure. The electron gun with a perveance of 1.53 P is designed. The gun has a voltage gradient lower than 22.1 kV/mm and a cathode load current lower than 6.3 A/cm2. The beam focusing system is a space-charge balanced flow type with solenoid magnet structure and the focusing beam trajectories have a good laminar condition. A single gap cavity is adopted instead of the traveling wave output structure in the initial beam-wave interaction simulation to decide the parameters of the cavities except the output structure. A C-band disc-loaded waveguide output structure working at /2 mode is designed and the dispersion and interaction impedance of the structure are determined by the CST code. The beam-wave interaction system with disc-loaded waveguide output structure is simulated by a three-dimensional PIC code. More than 50 MW output power is obtained. The efficiency is more than 45% and the saturate gain is more than 50 dB. The voltage gradient of the disc-loaded waveguide output structure is 30 percent less than that of the single gap cavity and there is an increase of 4% in efficiency above that of the single gap cavity.
This paper presents the simulation study of a C-band 50 MW klystron with disc-loaded waveguide traveling wave output structure. The electron gun with a perveance of 1.53 P is designed. The gun has a voltage gradient lower than 22.1 kV/mm and a cathode load current lower than 6.3 A/cm2. The beam focusing system is a space-charge balanced flow type with solenoid magnet structure and the focusing beam trajectories have a good laminar condition. A single gap cavity is adopted instead of the traveling wave output structure in the initial beam-wave interaction simulation to decide the parameters of the cavities except the output structure. A C-band disc-loaded waveguide output structure working at /2 mode is designed and the dispersion and interaction impedance of the structure are determined by the CST code. The beam-wave interaction system with disc-loaded waveguide output structure is simulated by a three-dimensional PIC code. More than 50 MW output power is obtained. The efficiency is more than 45% and the saturate gain is more than 50 dB. The voltage gradient of the disc-loaded waveguide output structure is 30 percent less than that of the single gap cavity and there is an increase of 4% in efficiency above that of the single gap cavity.
2012,
24: 2865-2868.
doi: 10.3788/HPLPB20122412.2865
Abstract:
With the help of 3D PIC software, the beam-wave interaction for a 0.4 THz confocal gyro-traveling-wave tube was simulated. With the consideration of cold dispersion characteristics and diffraction loss ofthe confocal waveguide, HE06 mode is chosen as the interaction working mode. For the purpose of suppressing competing mode, a sever structure is used. In the simulation process, with the adjusting of beam voltage, beam current, working magnetic field, and velocity ratio, the optimized working parameters are found. At last, the operating parameters are chosen as 34 kV beam voltage, 14.25 T magnetic field, 2 A beam current, 0.75 velocity ratio, and with the input power of 1 W, 2.76 kW output power is achieved. The gain exceeds 34 dB, the 3 dB bandwidth achieves 8 GHz, and the efficiency achieved 4%.
With the help of 3D PIC software, the beam-wave interaction for a 0.4 THz confocal gyro-traveling-wave tube was simulated. With the consideration of cold dispersion characteristics and diffraction loss ofthe confocal waveguide, HE06 mode is chosen as the interaction working mode. For the purpose of suppressing competing mode, a sever structure is used. In the simulation process, with the adjusting of beam voltage, beam current, working magnetic field, and velocity ratio, the optimized working parameters are found. At last, the operating parameters are chosen as 34 kV beam voltage, 14.25 T magnetic field, 2 A beam current, 0.75 velocity ratio, and with the input power of 1 W, 2.76 kW output power is achieved. The gain exceeds 34 dB, the 3 dB bandwidth achieves 8 GHz, and the efficiency achieved 4%.
2012,
24: 2869-2872.
doi: 10.3788/HPLPB20122412.2869
Abstract:
A kind of W-band oscillator is designed. To reduce space charge effects, a thin rectangular sheet electron beam with a width-to-height ratio of 2 is adopted. In order to increase power capacity of the cavity, the periodic coupling cavity slow wave line is selected as the high frequency structure. And the ladder gradient rectangular waveguide is used as the output structure that can make the output structure and high frequency structure match well. The 3D-PIC simulation program is utilized to analyze the effect of the cycle number and length of the slow wave structure on conversion efficiency. The simulation results show that, when the cathode voltage is 13.0-16.1 kV, the high frequency structure can work normally, and when the cycle number is 9, the cathode voltage is 15.7 kV, the output power and conversion efficiency are highest,with the output peak power more than 1.9 kW, the average power of 980 W, the work frequency of 91.6 GHz, and the conversion efficiency of 25%. With the periodic coupling cavity length increasing, the work frequency decreases.
A kind of W-band oscillator is designed. To reduce space charge effects, a thin rectangular sheet electron beam with a width-to-height ratio of 2 is adopted. In order to increase power capacity of the cavity, the periodic coupling cavity slow wave line is selected as the high frequency structure. And the ladder gradient rectangular waveguide is used as the output structure that can make the output structure and high frequency structure match well. The 3D-PIC simulation program is utilized to analyze the effect of the cycle number and length of the slow wave structure on conversion efficiency. The simulation results show that, when the cathode voltage is 13.0-16.1 kV, the high frequency structure can work normally, and when the cycle number is 9, the cathode voltage is 15.7 kV, the output power and conversion efficiency are highest,with the output peak power more than 1.9 kW, the average power of 980 W, the work frequency of 91.6 GHz, and the conversion efficiency of 25%. With the periodic coupling cavity length increasing, the work frequency decreases.
2012,
24: 2873-2876.
doi: 10.3788/HPLPB20122412.2873
Abstract:
A standard device based on a monocone has been proposed for calibration of ultra-wideband short-pulse electromagnetic field sensors. The distribution of electromagnetic field in the monocone can be computed in analytical form by the Maxwell equations, the source and the dimensions of the monocone. The finite-difference time-domain method has been used to design and optimize the device structure. The standard device has been manufactured and tested. The test results indicate that the electric field waveforms in the monocone and the source are consistent with each other, with the voltage reflection coefficient at the feed point less than 4% and the amplitude of the electric field deviating from the analytical value less than 6%.
A standard device based on a monocone has been proposed for calibration of ultra-wideband short-pulse electromagnetic field sensors. The distribution of electromagnetic field in the monocone can be computed in analytical form by the Maxwell equations, the source and the dimensions of the monocone. The finite-difference time-domain method has been used to design and optimize the device structure. The standard device has been manufactured and tested. The test results indicate that the electric field waveforms in the monocone and the source are consistent with each other, with the voltage reflection coefficient at the feed point less than 4% and the amplitude of the electric field deviating from the analytical value less than 6%.
2012,
24: 2877-2879.
doi: 10.3788/HPLPB20122412.2877
Abstract:
According to the main parameters of Heavy Ion Therapy Facility in Lanzhou (HITFL), the physical model of injection and extraction deflector is built by ANSYS code which is a 3D program for electromagnetic field calculation. In the calculation, the fillet radius and the half width of the high voltage electrode are set to 20 mm and 55 mm respectively. From the result, the non-uniformity of electric field is from -0.24 percent to 0.24 percent, and the coefficient of electric field is 1.37(less than 2), so the design of the deflector meets physical requirement. According to the experience of CSRm deflector in HIRFL-CSR project, the deflectors of HITFL are made of wrought aluminum with surface anodic oxidation in order to meet the requirement of the resist pressure and the mechanical strength.
According to the main parameters of Heavy Ion Therapy Facility in Lanzhou (HITFL), the physical model of injection and extraction deflector is built by ANSYS code which is a 3D program for electromagnetic field calculation. In the calculation, the fillet radius and the half width of the high voltage electrode are set to 20 mm and 55 mm respectively. From the result, the non-uniformity of electric field is from -0.24 percent to 0.24 percent, and the coefficient of electric field is 1.37(less than 2), so the design of the deflector meets physical requirement. According to the experience of CSRm deflector in HIRFL-CSR project, the deflectors of HITFL are made of wrought aluminum with surface anodic oxidation in order to meet the requirement of the resist pressure and the mechanical strength.
2012,
24: 2880-2884.
doi: 10.3788/HPLPB20122412.2880
Abstract:
In order to realize the HIRFL-CSR super-long-period slow extraction, the distributed control system of the CSR main ring(CSRm) power supply is designed based on high-speed Ethernet, with the controller of the power supply employing ARM+DSP architecture. The control cycle adopts multipart handling mechanism to solve the problem that the waveform data is too large to be stored in the controller. The control system has been tested in the HIRFL-CSR, and successfully conducted the carbon ions ten-thousand-second slow extraction.
In order to realize the HIRFL-CSR super-long-period slow extraction, the distributed control system of the CSR main ring(CSRm) power supply is designed based on high-speed Ethernet, with the controller of the power supply employing ARM+DSP architecture. The control cycle adopts multipart handling mechanism to solve the problem that the waveform data is too large to be stored in the controller. The control system has been tested in the HIRFL-CSR, and successfully conducted the carbon ions ten-thousand-second slow extraction.
2012,
24: 2885-2888.
doi: 10.3788/HPLPB20122412.2885
Abstract:
The Primary Stripper Foil Changer of Rapid Cycling Proton Synchrotron (RCS) in China Spallation Neutron Source (CSNS). In order to decreasing the development difficulties, costing and improving the reliability, the structure scheme of rotation structure has been adopted. Considering the technical difficulties of on-line adjustable, movement stability, positioning accuracy, ultra-high vacuum and so on, the detailed mechanical design and control system scheme of CSNS/RCS Primary Stripper Foil Changer have been carried out. And the Finite Element Analysis (FEA) Software ANSYS and Material Mechanics Theory have been utilized to simulate and analyze the devices core component (Stainless Steel Synchronous Belt).
The Primary Stripper Foil Changer of Rapid Cycling Proton Synchrotron (RCS) in China Spallation Neutron Source (CSNS). In order to decreasing the development difficulties, costing and improving the reliability, the structure scheme of rotation structure has been adopted. Considering the technical difficulties of on-line adjustable, movement stability, positioning accuracy, ultra-high vacuum and so on, the detailed mechanical design and control system scheme of CSNS/RCS Primary Stripper Foil Changer have been carried out. And the Finite Element Analysis (FEA) Software ANSYS and Material Mechanics Theory have been utilized to simulate and analyze the devices core component (Stainless Steel Synchronous Belt).
2012,
24: 2889-2892.
doi: 10.3788/HPLPB20122412.2889
Abstract:
PIC simulation is taken to get the oscillating process of the X band coaxial magnetron. Though the oscillating process would be affected by the spurious mode, the magnetron could work properly if the loss tangent of the attenuator exceeds 0.010. Otherwise the magnetron would be unable to work. So attenuators with loss tangent exceeding 0.010 are needed for coaxial magnetrons. The quality factors of the prime mode and N/2-1 mode in coaxial magnetrons with different attenuators are obtained. The results indicate that it would be effective to absorb N/2-1 mode if the loss tangent of attenuators exceeds 0.010, confirming the PIC results.
PIC simulation is taken to get the oscillating process of the X band coaxial magnetron. Though the oscillating process would be affected by the spurious mode, the magnetron could work properly if the loss tangent of the attenuator exceeds 0.010. Otherwise the magnetron would be unable to work. So attenuators with loss tangent exceeding 0.010 are needed for coaxial magnetrons. The quality factors of the prime mode and N/2-1 mode in coaxial magnetrons with different attenuators are obtained. The results indicate that it would be effective to absorb N/2-1 mode if the loss tangent of attenuators exceeds 0.010, confirming the PIC results.
2012,
24: 2893-2896.
doi: 10.3788/HPLPB20122412.2893
Abstract:
In the upgrade of Hefei Light Source (HLS), Libera Brilliance Single Pass is chosen to constitute a signal processing system in order to enhance the overall performance of the injector beam position monitor (BPM) system. The characterization test of the apparatus was made. The mapping of stripline BPM was carried out on a workbench with Libera Brilliance Single Pass. The beam position was tested at HLSs existing 200 MeV linear accelerator using Libera Brilliance Single Pass. The results show that the offline resolution is 4 m to 17 m, better than that of the original logarithmic processing system. The online horizontal and vertical resolution is better than 26 m and 19 m, respectively, also better than the existing systems 58 m and 33 m.
In the upgrade of Hefei Light Source (HLS), Libera Brilliance Single Pass is chosen to constitute a signal processing system in order to enhance the overall performance of the injector beam position monitor (BPM) system. The characterization test of the apparatus was made. The mapping of stripline BPM was carried out on a workbench with Libera Brilliance Single Pass. The beam position was tested at HLSs existing 200 MeV linear accelerator using Libera Brilliance Single Pass. The results show that the offline resolution is 4 m to 17 m, better than that of the original logarithmic processing system. The online horizontal and vertical resolution is better than 26 m and 19 m, respectively, also better than the existing systems 58 m and 33 m.
2012,
24: 2897-2900.
doi: 10.3788/HPLPB20122412.2897
Abstract:
In order to solve the communications blockage problem of the power supply digital adjustors in Lanzhou Heavy Ion Accelerator CSR, a new system architecture is adopted, P2P technology is embedded to the core processor ARM of the digital adjustor. Based on the technology of UDP holing, a direct communication connect is established between the adjustors, thus the data are no longer forwarded by the main Oracle database system acting as a server. This method decentralizes the communication responsibility of Oracle database system, the risk of network block is reduced, and the effectiveness and reliability of communication is improved.
In order to solve the communications blockage problem of the power supply digital adjustors in Lanzhou Heavy Ion Accelerator CSR, a new system architecture is adopted, P2P technology is embedded to the core processor ARM of the digital adjustor. Based on the technology of UDP holing, a direct communication connect is established between the adjustors, thus the data are no longer forwarded by the main Oracle database system acting as a server. This method decentralizes the communication responsibility of Oracle database system, the risk of network block is reduced, and the effectiveness and reliability of communication is improved.
2012,
24: 2901-2905.
doi: 10.3788/HPLPB20122412.2901
Abstract:
In order to obtain fine grain structure and improve laser cladding coating quality, Ni60CuMoW composite coating was fabricated by magnetic field assisted laser cladding technique on Q235 steel surface. The microstructure and phase composition of the cladding composite coating were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The cross-section hardness and abrasion performance of the cladding composite coating were measured by Vickers hardness tester and friction and wear device. The corrosion behaviors of the composite coatings were characterized through electrochemical test system. The results show that the phase of the laser cladding composite coatings is mainly composed of -（Ni, Cu）solid solution, silicides and borides. The Cr3Si grain is fine, uniform and compact. The average hardness of the composite coating is 913HV0.5, which is 1.5 times higher than that of the coating without magnetic field. The weight loss of laser cladding composite coating is only about 36% the coating without magnetic field. The corrosion potential increases about 100 mV, and corrosion current density decreases by 70%. The wear behaviors and corrosion resistance of the laser cladding composite coatings are significantly improved.
In order to obtain fine grain structure and improve laser cladding coating quality, Ni60CuMoW composite coating was fabricated by magnetic field assisted laser cladding technique on Q235 steel surface. The microstructure and phase composition of the cladding composite coating were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The cross-section hardness and abrasion performance of the cladding composite coating were measured by Vickers hardness tester and friction and wear device. The corrosion behaviors of the composite coatings were characterized through electrochemical test system. The results show that the phase of the laser cladding composite coatings is mainly composed of -（Ni, Cu）solid solution, silicides and borides. The Cr3Si grain is fine, uniform and compact. The average hardness of the composite coating is 913HV0.5, which is 1.5 times higher than that of the coating without magnetic field. The weight loss of laser cladding composite coating is only about 36% the coating without magnetic field. The corrosion potential increases about 100 mV, and corrosion current density decreases by 70%. The wear behaviors and corrosion resistance of the laser cladding composite coatings are significantly improved.
2012,
24: 2906-2910.
doi: 10.3788/HPLPB20122412.2906
Abstract:
An method the reduce the parallax error of multi-wire proportional chambers (MWPCs) was introduced. The principle of the parallax error reduction is to divide the electrode planes of the detector into a series of small units, and the potential of each unit was set according to its distance to the sample position. Calculation shows that the method can significantly reduce the parallax error of MWPCs, and almost not deteriorate of the detectors primary electron collection efficiency and gain uniformity of the anode plane.
An method the reduce the parallax error of multi-wire proportional chambers (MWPCs) was introduced. The principle of the parallax error reduction is to divide the electrode planes of the detector into a series of small units, and the potential of each unit was set according to its distance to the sample position. Calculation shows that the method can significantly reduce the parallax error of MWPCs, and almost not deteriorate of the detectors primary electron collection efficiency and gain uniformity of the anode plane.
2012,
24: 2911-2914.
doi: 10.3788/HPLPB20122412.2911
Abstract:
A 2.45 GHz electron cyclotron resonance ion source with permanent magnets has been developed. Its outline dimension is 160 mm in diameter and 90 mm in height, the discharge chambers dimension is 70 mm in diameter and 50 mm in height. The microwave window is made of a f50 mm10 mm BN disk and two f30 mm10 mm ceramic disks. This ion source adopts a three-electrode extraction system and works in the pulsed mode. When the microwave input power is 300 W, the air inflow is 0.4 mL/min, a more than 30 mA peak current of the nitrogen beam can be extracted from a 5 mm emission aperture at 100 kV extraction voltage. The diameter of the beam uniform area on the working plane is more than 200 mm.
A 2.45 GHz electron cyclotron resonance ion source with permanent magnets has been developed. Its outline dimension is 160 mm in diameter and 90 mm in height, the discharge chambers dimension is 70 mm in diameter and 50 mm in height. The microwave window is made of a f50 mm10 mm BN disk and two f30 mm10 mm ceramic disks. This ion source adopts a three-electrode extraction system and works in the pulsed mode. When the microwave input power is 300 W, the air inflow is 0.4 mL/min, a more than 30 mA peak current of the nitrogen beam can be extracted from a 5 mm emission aperture at 100 kV extraction voltage. The diameter of the beam uniform area on the working plane is more than 200 mm.
2012,
24: 2915-2919.
doi: 10.3788/HPLPB20122412.2915
Abstract:
The setting method of electron emission boundary in cavity system generate electromagnetic pulse(SGEMP) simulation is researched. The electron emission boundary in bottom incidence cavity SGEMP simulation is introduced, and the peculiarity of the boundary in side incidence cavity SGEMP simulation is analyzed. By the employment of virtual-emission-surface, the electron emission boundary in side incidence cavity SGEMP simulation is realized. It is indicated that by using the method mentioned here one can achieve the electron emission boundary efficiently, both in flat and curved surface boundary condition, and the parameters and emission sequence of electron on the boundary obey the corresponding physical laws.
The setting method of electron emission boundary in cavity system generate electromagnetic pulse(SGEMP) simulation is researched. The electron emission boundary in bottom incidence cavity SGEMP simulation is introduced, and the peculiarity of the boundary in side incidence cavity SGEMP simulation is analyzed. By the employment of virtual-emission-surface, the electron emission boundary in side incidence cavity SGEMP simulation is realized. It is indicated that by using the method mentioned here one can achieve the electron emission boundary efficiently, both in flat and curved surface boundary condition, and the parameters and emission sequence of electron on the boundary obey the corresponding physical laws.
2012,
24: 2920-2924.
doi: 10.3788/HPLPB20122412.2920
Abstract:
The cloud-and-fog scattering effect will produce laser signals resulting in false alarm for laser fuse. Based on the Monte-Carlo technology, backscattering signals of clouds and fogs are simulated and compared with results of the experiment carried out in the cloud-and-fog chamber. Results show that the pulse broadening effect mainly introduced by multiple scattering is drastical when the transmitting pulse width is less than 10 ns. And the theoretically calculated data are in good agreement with the experimental data. The temporal shapes are both close to Gaussian shape, and theoretically calculated results differ from experimental results by less than 6% for the width of the backscattering signal and 30% for the intensity of the backscattering signal.
The cloud-and-fog scattering effect will produce laser signals resulting in false alarm for laser fuse. Based on the Monte-Carlo technology, backscattering signals of clouds and fogs are simulated and compared with results of the experiment carried out in the cloud-and-fog chamber. Results show that the pulse broadening effect mainly introduced by multiple scattering is drastical when the transmitting pulse width is less than 10 ns. And the theoretically calculated data are in good agreement with the experimental data. The temporal shapes are both close to Gaussian shape, and theoretically calculated results differ from experimental results by less than 6% for the width of the backscattering signal and 30% for the intensity of the backscattering signal.
2012,
24: 2925-2929.
doi: 10.3788/HPLPB20122412.2925
Abstract:
The surface flashover character of insulator in vacuum under self-magnetic field is investigated in this paper through the principle of magnetic flashover inhibition (MFI). Considering the calculation of the critical ratio between electric and magnetic field, a coaxial electrode was designed to carry out experiments under three different conditions: the self-magnetic field flashover inhibition, the self-magnetic field flashover acceleration and none magnetic field. The results show that the insulator surface flashover voltage is improved about 15% with the self-magnetic field flashover inhibition and is reduced about 18% with the self-magnetic field flashover enhancement compared with that without magnetic field.
The surface flashover character of insulator in vacuum under self-magnetic field is investigated in this paper through the principle of magnetic flashover inhibition (MFI). Considering the calculation of the critical ratio between electric and magnetic field, a coaxial electrode was designed to carry out experiments under three different conditions: the self-magnetic field flashover inhibition, the self-magnetic field flashover acceleration and none magnetic field. The results show that the insulator surface flashover voltage is improved about 15% with the self-magnetic field flashover inhibition and is reduced about 18% with the self-magnetic field flashover enhancement compared with that without magnetic field.
2012,
24: 2930-2934.
doi: 10.3788/HPLPB20122412.2930
Abstract:
A small size 3D fiber-optic electric field sensor for measurement of electromagnetic pulse (EMP) in small volumes is developed. The influence of the sensor structure on the tested field is analyzed by CST2011. Meanwhile, the disturbance from shielding enclosure can be effectively reduced by simulating its embedded and spherical structure. The sensor interelectrode coupling and the three-dimensional field error of the synthesized field are discussed. Design parameters are defined based on the analysis results. A conformal sensor structure is utilized to act both as the dipole antenna and the shielding enclosure. The shielding efficiency of the external electric field can reach 60 dB. Experiments in the bounded-wave EMP simulator show the sensor can meet the requirements for three-dimensional electric field measurement and has smaller perturbation to the measured field. The interelectrode coupling coefficient is less than 6% and the error of the synthesized field is less than 5%. The balanced structure of the sensor makes it suitable for EMP measurement in small volumes and in free field.
A small size 3D fiber-optic electric field sensor for measurement of electromagnetic pulse (EMP) in small volumes is developed. The influence of the sensor structure on the tested field is analyzed by CST2011. Meanwhile, the disturbance from shielding enclosure can be effectively reduced by simulating its embedded and spherical structure. The sensor interelectrode coupling and the three-dimensional field error of the synthesized field are discussed. Design parameters are defined based on the analysis results. A conformal sensor structure is utilized to act both as the dipole antenna and the shielding enclosure. The shielding efficiency of the external electric field can reach 60 dB. Experiments in the bounded-wave EMP simulator show the sensor can meet the requirements for three-dimensional electric field measurement and has smaller perturbation to the measured field. The interelectrode coupling coefficient is less than 6% and the error of the synthesized field is less than 5%. The balanced structure of the sensor makes it suitable for EMP measurement in small volumes and in free field.
2012,
24: 2935-2940.
doi: 10.3788/HPLPB20122412.2935
Abstract:
The discrimination of nuclear-explosion and lightning electromagnetic pulses was studied using empirical mode decomposition and the fractal analytical method. The box dimensions of nuclear-explosion and lightning electromagnetic pulses original signals were calculated, and the box dimensions of the intrinsic mode functions (IMFs) of nuclear-explosion and lightning electromagnetic pulses original signals after empirical mode decomposition were also obtained. The discrimination of nuclear explosion and lightning was studied using the nearest neighbor pattern classification. The experimental results show that, the discrimination rate of the box dimension based on the first and second IMF after the original signal empirical mode decomposition is higher than that based on the third and forth IMF;the discrimination rate of the box dimension based on the original signal is higher than that based on any IMF;and the discrimination rate based on two-dimensional and three-dimensional characters is higher and more stable than that based on one-dimensional character, besides, the discrimination rate based on three-dimensional character is over 90%.
The discrimination of nuclear-explosion and lightning electromagnetic pulses was studied using empirical mode decomposition and the fractal analytical method. The box dimensions of nuclear-explosion and lightning electromagnetic pulses original signals were calculated, and the box dimensions of the intrinsic mode functions (IMFs) of nuclear-explosion and lightning electromagnetic pulses original signals after empirical mode decomposition were also obtained. The discrimination of nuclear explosion and lightning was studied using the nearest neighbor pattern classification. The experimental results show that, the discrimination rate of the box dimension based on the first and second IMF after the original signal empirical mode decomposition is higher than that based on the third and forth IMF;the discrimination rate of the box dimension based on the original signal is higher than that based on any IMF;and the discrimination rate based on two-dimensional and three-dimensional characters is higher and more stable than that based on one-dimensional character, besides, the discrimination rate based on three-dimensional character is over 90%.
2012,
24: 2941-2945.
doi: 10.3788/HPLPB20122412.2941
Abstract:
Deep-penetration problem has been one of the difficult problems in shielding calculation with Monte Carlo method for several decades. In this paper, a kind of particle transport random walking system under the emission point as a sampling station is built. Then, an adaptive sampling scheme is derived for better solution with the achieved information. The main advantage of the adaptive scheme is to choose the most suitable sampling number from the emission point station to obtain the minimum value of the total cost in the process of the random walk. Further, the related importance sampling method is introduced. Its main principle is to define the importance function due to the particle state and to ensure the sampling number of the emission particle is proportional to the importance function. The numerical results show that the adaptive scheme under the emission point as a station could overcome the difficulty of underestimation of the result in some degree, and the adaptive importance sampling method gets satisfied results as well.
Deep-penetration problem has been one of the difficult problems in shielding calculation with Monte Carlo method for several decades. In this paper, a kind of particle transport random walking system under the emission point as a sampling station is built. Then, an adaptive sampling scheme is derived for better solution with the achieved information. The main advantage of the adaptive scheme is to choose the most suitable sampling number from the emission point station to obtain the minimum value of the total cost in the process of the random walk. Further, the related importance sampling method is introduced. Its main principle is to define the importance function due to the particle state and to ensure the sampling number of the emission particle is proportional to the importance function. The numerical results show that the adaptive scheme under the emission point as a station could overcome the difficulty of underestimation of the result in some degree, and the adaptive importance sampling method gets satisfied results as well.
2012,
24: 2946-2950.
doi: 10.3788/HPLPB20122412.2946
Abstract:
Coupling of the Monte Carlo (MC) method and the discrete ordinate (SN) method is studied. An SN-MC coupling scheme is adopted in order to eliminate low sampling efficiency of the MC method and difficulty in complex geometrical modeling of the SN method. In the coupling method, the SN code provides neutron angular flux, and a coupling program is used to calculate probability distributions of surface sources. A modified source sampling subroutine is used to produce a combined surface source which contains bottom, top and side surfaces at the same time, and then a Monte Carlo calculation is performed. Preliminary numerical results demonstrate that the coupling method is correct and it can be used in pressurized water reactor cavity radiation streaming calculation.
Coupling of the Monte Carlo (MC) method and the discrete ordinate (SN) method is studied. An SN-MC coupling scheme is adopted in order to eliminate low sampling efficiency of the MC method and difficulty in complex geometrical modeling of the SN method. In the coupling method, the SN code provides neutron angular flux, and a coupling program is used to calculate probability distributions of surface sources. A modified source sampling subroutine is used to produce a combined surface source which contains bottom, top and side surfaces at the same time, and then a Monte Carlo calculation is performed. Preliminary numerical results demonstrate that the coupling method is correct and it can be used in pressurized water reactor cavity radiation streaming calculation.
2012,
24: 2951-2954.
doi: 10.3788/HPLPB20122412.2951
Abstract:
Based on the consideration of intellectual property, in order to find an alternative code of MCNP, the validity of FLUKA applied to the calculation of neutron fluence in reactor pressure vessel was studied by means of comparison of calculation results of the both codes. The secondary particle stack was manipulated by modifying and calling the user subroutines, and then the key problem of turning off the transportation of fission neutrons was solved. The results of FLUKA and MCNP code agree well with each other, with the relative deviation less than 5%. It is concluded that using FLUKA code in place of MCNP code is technically feasible.
Based on the consideration of intellectual property, in order to find an alternative code of MCNP, the validity of FLUKA applied to the calculation of neutron fluence in reactor pressure vessel was studied by means of comparison of calculation results of the both codes. The secondary particle stack was manipulated by modifying and calling the user subroutines, and then the key problem of turning off the transportation of fission neutrons was solved. The results of FLUKA and MCNP code agree well with each other, with the relative deviation less than 5%. It is concluded that using FLUKA code in place of MCNP code is technically feasible.
2012,
24: 2955-2958.
doi: 10.3788/HPLPB20122412.2955
Abstract:
A class of sampling tools for general Monte Carlo particle transport code JMCT is designed. Two ways are provided to sample from distributions. One is the utilization of special sampling methods for special distribution;the other is the utilization of general sampling methods for arbitrary discrete distribution and one-dimensional continuous distribution on a finite interval. Some open source codes are included in the general sampling method for the maximum convenience of users. The sampling results show sampling correctly from distributions which are popular in particle transport can be achieved with these tools, and the users convenience can be assured.
A class of sampling tools for general Monte Carlo particle transport code JMCT is designed. Two ways are provided to sample from distributions. One is the utilization of special sampling methods for special distribution;the other is the utilization of general sampling methods for arbitrary discrete distribution and one-dimensional continuous distribution on a finite interval. Some open source codes are included in the general sampling method for the maximum convenience of users. The sampling results show sampling correctly from distributions which are popular in particle transport can be achieved with these tools, and the users convenience can be assured.
2012,
24: 2959-2964.
doi: 10.3788/HPLPB20122412.2959
Abstract:
In order to simulate high-energy proton radiography quickly, the code Quick Monte Carlo Proton Radiography(QMCPrad) is developed by using MC technique and MC skills. The code is proven correct by comparing the simulation results to MCNPXs and simulating the experiment E955. In the QMCPrad, the nuclear interaction is modeled with the explicit capture model, and the multiple Coulomb scatter is treated with the condensed history method as one scatter during the proton passing through the object. These two methods reduce amounts of time for simulation. The code QMCPrad has the capability to simulate the proton transport in quadrupole. The comparison between the QMCPrad and MCNPX and the simulation result of E955 show that the QMCPrad can simulate the high-energy proton radiography quantificationally, andis a useful tool for the design of proton radiography.
In order to simulate high-energy proton radiography quickly, the code Quick Monte Carlo Proton Radiography(QMCPrad) is developed by using MC technique and MC skills. The code is proven correct by comparing the simulation results to MCNPXs and simulating the experiment E955. In the QMCPrad, the nuclear interaction is modeled with the explicit capture model, and the multiple Coulomb scatter is treated with the condensed history method as one scatter during the proton passing through the object. These two methods reduce amounts of time for simulation. The code QMCPrad has the capability to simulate the proton transport in quadrupole. The comparison between the QMCPrad and MCNPX and the simulation result of E955 show that the QMCPrad can simulate the high-energy proton radiography quantificationally, andis a useful tool for the design of proton radiography.
2012,
24: 2965-2969.
doi: 10.3788/HPLPB20122412.2965
Abstract:
MPI parallelization of Monte Carlo code FXRMC for flash X-ray radiography is investigated, and the method of generating parallel random numbers is presented. Test resultsshow that the results of both parallel and sequential codes are identical. The acceleration ratio is linear to the number of processors, and the parallel efficiency exceeds 80% for 16 processors. Calculation examples indicate that parallelization has effectively solved the time-consuming problem of the code in the process of computing scattering, thus improving calculation scale and speed of FXRMC.
MPI parallelization of Monte Carlo code FXRMC for flash X-ray radiography is investigated, and the method of generating parallel random numbers is presented. Test resultsshow that the results of both parallel and sequential codes are identical. The acceleration ratio is linear to the number of processors, and the parallel efficiency exceeds 80% for 16 processors. Calculation examples indicate that parallelization has effectively solved the time-consuming problem of the code in the process of computing scattering, thus improving calculation scale and speed of FXRMC.
2012,
24: 2970-2974.
doi: 10.3788/HPLPB20122412.2970
Abstract:
In the case of radiation therapy and BNCT, alpha particles transport the energy to human tissue by second electrons. However, in cellular scale alpha sources do not have a uniform distribution. In order to get the target dosimetry discrepancy by different source locations, a computational application to calculate the S value with Monte Carlo toolkit Geant4 was programmed. S values of two dimensions, twelve energies, and three source locations were calculated. Compared with MIRD results, the difference between both is within 1%. Geant4 toolkit to calculate the cell dosimetry was proved to be believable and flexible. A couple of S values of alpha particles produced in BNCT with 1.47 MeV and 1.78 MeV were calculated. To some extent these values can become reference values in clinical therapy.
In the case of radiation therapy and BNCT, alpha particles transport the energy to human tissue by second electrons. However, in cellular scale alpha sources do not have a uniform distribution. In order to get the target dosimetry discrepancy by different source locations, a computational application to calculate the S value with Monte Carlo toolkit Geant4 was programmed. S values of two dimensions, twelve energies, and three source locations were calculated. Compared with MIRD results, the difference between both is within 1%. Geant4 toolkit to calculate the cell dosimetry was proved to be believable and flexible. A couple of S values of alpha particles produced in BNCT with 1.47 MeV and 1.78 MeV were calculated. To some extent these values can become reference values in clinical therapy.
2012,
24: 2975-2978.
doi: 10.3788/HPLPB20122412.2975
Abstract:
The purpose of this work is to simulate 6 MV Varian Truebeam linac dosimeter characteristics using Monte Carlo method and to investigate the availability of phase space file and the accuracy of the simulation. With the phase space file at linac window supplied by Varian to be a source, the patient-dependent part was simulated. Dose distributions in a water phantom with a 10 cm10 cm field were calculated and compared with measured data for validation. Evident time reduction was obtained from 4-5 h which a whole simulation cost on the same computer to around 48 minutes. Good agreement between simulations and measurements in water was observed. Dose differences are less than 3% for depth doses in build-up region and also for dose profiles inside the 80% field size, and the effect in penumbra is good. It demonstrate that the simulation using existing phase space file as the EGSnrc source is efficient. Dose differences between calculated data and measured data could meet the requirements for dose calculation.
The purpose of this work is to simulate 6 MV Varian Truebeam linac dosimeter characteristics using Monte Carlo method and to investigate the availability of phase space file and the accuracy of the simulation. With the phase space file at linac window supplied by Varian to be a source, the patient-dependent part was simulated. Dose distributions in a water phantom with a 10 cm10 cm field were calculated and compared with measured data for validation. Evident time reduction was obtained from 4-5 h which a whole simulation cost on the same computer to around 48 minutes. Good agreement between simulations and measurements in water was observed. Dose differences are less than 3% for depth doses in build-up region and also for dose profiles inside the 80% field size, and the effect in penumbra is good. It demonstrate that the simulation using existing phase space file as the EGSnrc source is efficient. Dose differences between calculated data and measured data could meet the requirements for dose calculation.
2012,
24: 2979-2982.
doi: 10.3788/HPLPB20122412.2979
Abstract:
Induced radionuclides in probe bombarded with proton beam will turn the detector into a typical external irradiation radiation source. It is beneficial for developing radiation protection to calculate the kinds and the activity of induced radionuclides. Here, the induced radioactivity for three types of probe materials (Cu, Ta and W) irradiated by low-energy (below 20 MeV) proton beam are separately simulated the FLUKA Monte-Carle program. The results show that the energy threshold of induced radioactivity in the copper probe is the lowest (about 4-5 MeV) compared with those in the tungsten and tantalum probes (about 10 MeV). In addition, the total induced radioactivity of the copper probe is always higher than the other two under the same irradiation time with decay time up to 1 hour.
Induced radionuclides in probe bombarded with proton beam will turn the detector into a typical external irradiation radiation source. It is beneficial for developing radiation protection to calculate the kinds and the activity of induced radionuclides. Here, the induced radioactivity for three types of probe materials (Cu, Ta and W) irradiated by low-energy (below 20 MeV) proton beam are separately simulated the FLUKA Monte-Carle program. The results show that the energy threshold of induced radioactivity in the copper probe is the lowest (about 4-5 MeV) compared with those in the tungsten and tantalum probes (about 10 MeV). In addition, the total induced radioactivity of the copper probe is always higher than the other two under the same irradiation time with decay time up to 1 hour.
2012,
24: 2983-2986.
doi: 10.3788/HPLPB20122412.2983
Abstract:
This paper simulates the physical process of high energy radiography with the Monte Carlo method providing the analog image for edge detection, and to fix the boundaries of experimental images based on the analog image boundary degradation. More precise object boundary is obtained by iterative calculation. The accuracy and reliability of the method is validated by the means of numerical calculation, experimental image processing results show that: the error value of the boundary obtained by Canny operator is several pixel size, and after the amendment it is reduced to a pixel size or lower. So compared to the pre-revised accuracy is improved significantly.
This paper simulates the physical process of high energy radiography with the Monte Carlo method providing the analog image for edge detection, and to fix the boundaries of experimental images based on the analog image boundary degradation. More precise object boundary is obtained by iterative calculation. The accuracy and reliability of the method is validated by the means of numerical calculation, experimental image processing results show that: the error value of the boundary obtained by Canny operator is several pixel size, and after the amendment it is reduced to a pixel size or lower. So compared to the pre-revised accuracy is improved significantly.
2012,
24: 2987-2990.
doi: 10.3788/HPLPB20122412.2987
Abstract:
The Monte Carlo method-based Geant4 program is used to simulate the parallel muons (which are perpendicular to the ideal detectors) injecting into the French Test Object (FTO) model. Six ideal detectors, three over the model and three under it, are used to output the positions of muons, with which the incident and scattered muons tracks can be determined. Different transmission images of the FTO model can be obtained through calculating the transmission ratio before and after the model with three methods. The resolution of the first method and the second method is 2 mm2 mm, while the resolution of the third method is 1 mm1 mm and the edge of Cu and W can be distinguished obviously. Even the air sphere in the center of the FTO model can be observed visibly. Through all the three methods, the boundaries of the FTO model and the air outside it are very clear. The simulation results of transmission imaging indicate that the methods of parallel incident muons is feasible and practicable.
The Monte Carlo method-based Geant4 program is used to simulate the parallel muons (which are perpendicular to the ideal detectors) injecting into the French Test Object (FTO) model. Six ideal detectors, three over the model and three under it, are used to output the positions of muons, with which the incident and scattered muons tracks can be determined. Different transmission images of the FTO model can be obtained through calculating the transmission ratio before and after the model with three methods. The resolution of the first method and the second method is 2 mm2 mm, while the resolution of the third method is 1 mm1 mm and the edge of Cu and W can be distinguished obviously. Even the air sphere in the center of the FTO model can be observed visibly. Through all the three methods, the boundaries of the FTO model and the air outside it are very clear. The simulation results of transmission imaging indicate that the methods of parallel incident muons is feasible and practicable.
2012,
24: 2991-2995.
doi: 10.3788/HPLPB20122412.2991
Abstract:
The accurate Monte Carlo (MC) simulation of scattering X-ray intensity is crucial in high energy flash radiography. On the basis of introducing the calculation method of exposure, a way for experimentally testifying the MC scattering simulation is proposed according to the main seattering source. The key is to construct a pair of correlated experiments which have the same direct component and different seattering component, so their image gray difference is related to their scattering difference X, where G can be measured experimentally and X can be calculated by MC simulation. G and are measured and calculated in three different radiography models. It is found that in all the three models the G have similar distribution with X, and the ratio G/X is nearly same as 4.95. This confirms the validation of the method and also confirms the correctness of the MC scattering simulation results.
The accurate Monte Carlo (MC) simulation of scattering X-ray intensity is crucial in high energy flash radiography. On the basis of introducing the calculation method of exposure, a way for experimentally testifying the MC scattering simulation is proposed according to the main seattering source. The key is to construct a pair of correlated experiments which have the same direct component and different seattering component, so their image gray difference is related to their scattering difference X, where G can be measured experimentally and X can be calculated by MC simulation. G and are measured and calculated in three different radiography models. It is found that in all the three models the G have similar distribution with X, and the ratio G/X is nearly same as 4.95. This confirms the validation of the method and also confirms the correctness of the MC scattering simulation results.
2012,
24: 2996-3000.
doi: 10.3788/HPLPB20122412.2996
Abstract:
The supercritical water reactor is one of the six reactors recommended by Generation IV International Forum. Compared with existing light water reactors, the supercritical water reactor has advantages of high thermal efficiency, simplified system structure and low cost. The physical model of the supercritical water reactor is established with MCNP program in this paper, which solves the problem of intricate geometry of fuel assembly. The change of coolant density along the axis is considered and the neutron spectrum distribution of different regions of the core is calculated. The safety in loss of coolant accident for the supercritical water reactor and the effect of missing coolant in different regions on the reactivity and effective multiplication factor analyzed. The results show the supercritical water reactor core has high security. The countermeasures of loss of coolant accident is studied and the effectiveness of boron water cooling is validated. The research not only provide important reference for the construction and security analysis of the supercritical water reactor, but also has great significance for the application and development of the supercritical water reactor.
The supercritical water reactor is one of the six reactors recommended by Generation IV International Forum. Compared with existing light water reactors, the supercritical water reactor has advantages of high thermal efficiency, simplified system structure and low cost. The physical model of the supercritical water reactor is established with MCNP program in this paper, which solves the problem of intricate geometry of fuel assembly. The change of coolant density along the axis is considered and the neutron spectrum distribution of different regions of the core is calculated. The safety in loss of coolant accident for the supercritical water reactor and the effect of missing coolant in different regions on the reactivity and effective multiplication factor analyzed. The results show the supercritical water reactor core has high security. The countermeasures of loss of coolant accident is studied and the effectiveness of boron water cooling is validated. The research not only provide important reference for the construction and security analysis of the supercritical water reactor, but also has great significance for the application and development of the supercritical water reactor.
2012,
24: 3001-3005.
doi: 10.3788/HPLPB20122412.3001
Abstract:
The physical model of the 300# swimming pool research reactor(SPRR-300) based on the Monte Carlo code MCNP has been verified. Sophisticated modeling is conducted. An effective multiplication factor value of 1.002 29 is obtained, existing a relative error of 0.229% compared with the critical value. Meanwhile, a problem comes out that the interrupt and continue-run with parallel version of MCNP doesnt work. The problem is solved through trail and error process. A reasonable application of flux tally average over a cell and flux tally at a point is suggested, namely the former is prior to the latter to tally in big volume. Comparison between calculation results and experimental data shows that the thermal neutron flux has a deviation of 4.6% at a power level of 3 MW. That is to say, the calculated value and the experimental value agree well with each other, and the neutron flux result is dependable.
The physical model of the 300# swimming pool research reactor(SPRR-300) based on the Monte Carlo code MCNP has been verified. Sophisticated modeling is conducted. An effective multiplication factor value of 1.002 29 is obtained, existing a relative error of 0.229% compared with the critical value. Meanwhile, a problem comes out that the interrupt and continue-run with parallel version of MCNP doesnt work. The problem is solved through trail and error process. A reasonable application of flux tally average over a cell and flux tally at a point is suggested, namely the former is prior to the latter to tally in big volume. Comparison between calculation results and experimental data shows that the thermal neutron flux has a deviation of 4.6% at a power level of 3 MW. That is to say, the calculated value and the experimental value agree well with each other, and the neutron flux result is dependable.
2012,
24: 3006-3010.
doi: 10.3788/HPLPB20122412.3006
Abstract:
Based on the Monte Carlo particle transport program MCNP, a novel glass fiber/B4C/epoxy resin composite for neutron shielding with high strength and low density was developed. Its neutron transmissivity was calculated under the Am-Be neutron source condition to study the difference of neutron shielding performance between the glass fiber/B4C/epoxy resin composite and traditional shielding materials. Furthermore, effects of B4C mass fraction of the composite on the shielding performance for neutrons with different energy(slow neutron, intermediate neutron, fast neutron) were analyzed. The results show the composites with 10% B4C mass contents have more advantages on the neutron shielding performance , especially the slow neutron shielding performance in comparison with polyethylene/boron containing composites and Al-B4C alloy. With the further increasing of the B4C contents, no remarkable increase is observed. Monte Carlo method is demonstrated feasible in optimization design of neutron shielding materials and the results provide a theoretical basis for design and preparation of a new neutron shielding composite.
Based on the Monte Carlo particle transport program MCNP, a novel glass fiber/B4C/epoxy resin composite for neutron shielding with high strength and low density was developed. Its neutron transmissivity was calculated under the Am-Be neutron source condition to study the difference of neutron shielding performance between the glass fiber/B4C/epoxy resin composite and traditional shielding materials. Furthermore, effects of B4C mass fraction of the composite on the shielding performance for neutrons with different energy(slow neutron, intermediate neutron, fast neutron) were analyzed. The results show the composites with 10% B4C mass contents have more advantages on the neutron shielding performance , especially the slow neutron shielding performance in comparison with polyethylene/boron containing composites and Al-B4C alloy. With the further increasing of the B4C contents, no remarkable increase is observed. Monte Carlo method is demonstrated feasible in optimization design of neutron shielding materials and the results provide a theoretical basis for design and preparation of a new neutron shielding composite.
2012,
24: 3011-3014.
doi: 10.3788/HPLPB20122412.3011
Abstract:
The longitudinal and lateral straggling was analyzed in the irradiation of hot electrons into DD and DT fusion plasma. The result shows that the longitudinal and lateral straggling linearly increases with increasing the penetration range which is in some relation to plasma mass. The calculated error mainly results from the lateral straggling, with the value below 5%, or millions of amperes. When the electron energy is fully deposited in the hot spot, the focusing angle is 20.64 for DD plasma and 21.8 for DT plasma in the edge-ignition mode, and is 16.36 for DD plasma and 17.6 for DT plasma in the center-ignition mode. The condition for the electronic beam focusing angle is easily achieved.
The longitudinal and lateral straggling was analyzed in the irradiation of hot electrons into DD and DT fusion plasma. The result shows that the longitudinal and lateral straggling linearly increases with increasing the penetration range which is in some relation to plasma mass. The calculated error mainly results from the lateral straggling, with the value below 5%, or millions of amperes. When the electron energy is fully deposited in the hot spot, the focusing angle is 20.64 for DD plasma and 21.8 for DT plasma in the edge-ignition mode, and is 16.36 for DD plasma and 17.6 for DT plasma in the center-ignition mode. The condition for the electronic beam focusing angle is easily achieved.
2012,
24: 3015-3018.
doi: 10.3788/HPLPB20122412.3015
Abstract:
Muon radiation background of China Jinping Underground Laboratory (CJPL) was simulated by Monte Carlo method. According to the Gaisser formula and the MUSIC soft, the model of cosmic ray muons was established. Then the yield and the average energy of muon-induced photons and muon-induced neutrons were simulated by FLUKA. With the single-energy approximation, the contribution to the radiation background of shielding structure by secondary photons and neutrons was evaluated. The estimation results show that the average energy of residual muons is 369 GeV and the flux is 3.1710-6m-2s-1. The fluence rate of secondary photons is about 1.5710-4 m-2s-1, and the fluence rate of secondary neutrons is about 8.3710-7 m-2s-1. The muon radiation background of CJPL is lower than those of most other underground laboratories in the world.
Muon radiation background of China Jinping Underground Laboratory (CJPL) was simulated by Monte Carlo method. According to the Gaisser formula and the MUSIC soft, the model of cosmic ray muons was established. Then the yield and the average energy of muon-induced photons and muon-induced neutrons were simulated by FLUKA. With the single-energy approximation, the contribution to the radiation background of shielding structure by secondary photons and neutrons was evaluated. The estimation results show that the average energy of residual muons is 369 GeV and the flux is 3.1710-6m-2s-1. The fluence rate of secondary photons is about 1.5710-4 m-2s-1, and the fluence rate of secondary neutrons is about 8.3710-7 m-2s-1. The muon radiation background of CJPL is lower than those of most other underground laboratories in the world.
2012,
24: 3019-3022.
doi: 10.3788/HPLPB20122412.3019
Abstract:
The effect of self-generated magnetic field of electron beams produced by laser irradiating on metal wires on the divergence of the electron beams is studied. The theoretical analysis and magnitude order estimation show that, between the laser spot and the right end of the wire, the electrons are subject to both electrostatic and self-generated magnetic fields, which leads to considerable collimation, and during their motion from the right end of the wire to IP stacks, the space-charge field and magnetic field roughly cancel each other and the divergence is maintained roughly. The classic trajectory Monte Carlo method is used to simulate this process, and the simulation result indicates that both the electron beam divergence and its dependence on wire length could be explained by the self-generated magnetic field.
The effect of self-generated magnetic field of electron beams produced by laser irradiating on metal wires on the divergence of the electron beams is studied. The theoretical analysis and magnitude order estimation show that, between the laser spot and the right end of the wire, the electrons are subject to both electrostatic and self-generated magnetic fields, which leads to considerable collimation, and during their motion from the right end of the wire to IP stacks, the space-charge field and magnetic field roughly cancel each other and the divergence is maintained roughly. The classic trajectory Monte Carlo method is used to simulate this process, and the simulation result indicates that both the electron beam divergence and its dependence on wire length could be explained by the self-generated magnetic field.
2012,
24: 3023-3027.
doi: 10.3788/HPLPB20122412.3023
Abstract:
This paper introduces the foundation of the Monte Carlo method and the way how to generate the random numbers. Based on the basic thought of the Monte Carlo method and the finite differential method, the stochastic model for solving the boundary value problem of differential equations is built. To investigate the application of the Monte Carlo method to solving the boundary value problem of differential equations, the model is used to solve Laplaces equations with the first boundary condition and the unsteady heat transfer equation with initial values and boundary conditions. The results show that the boundary value problem of differential equations can be effectively solved with the Monte Carlo method, and the differential equations with initial condition can also be calculated by using a stochastic probability model which is based on the time-domain finite differential equations. Both the simulation results and theoretical analyses show that the errors of numerical results are lowered as the number of simulation particles is increased.
This paper introduces the foundation of the Monte Carlo method and the way how to generate the random numbers. Based on the basic thought of the Monte Carlo method and the finite differential method, the stochastic model for solving the boundary value problem of differential equations is built. To investigate the application of the Monte Carlo method to solving the boundary value problem of differential equations, the model is used to solve Laplaces equations with the first boundary condition and the unsteady heat transfer equation with initial values and boundary conditions. The results show that the boundary value problem of differential equations can be effectively solved with the Monte Carlo method, and the differential equations with initial condition can also be calculated by using a stochastic probability model which is based on the time-domain finite differential equations. Both the simulation results and theoretical analyses show that the errors of numerical results are lowered as the number of simulation particles is increased.
2012,
24: 3028-3032.
doi: 10.3788/HPLPB20122412.3028
Abstract:
Proton and alpha differential spectrum from galactic cosmic radiation(GCR) and solar particle event (SPE) were analyzed, also calculations about inside shielding environment and skin dose were performed. Through simulation we confirmed the precise of Geant4 again. The depth dose distribution of the inside radiation was calculated to get more information about the space environment inside shielding. As a conclusion, both with GCR proton and alpha particle there is no obvious decrease of dose with Al shielding, however, SPE spectrum does weaken as it has different energy distribution. We calculated the skin dose under different shielding thickness of 1972 SPE, obvious dose decrease was attained with increase shielding thickness.
Proton and alpha differential spectrum from galactic cosmic radiation(GCR) and solar particle event (SPE) were analyzed, also calculations about inside shielding environment and skin dose were performed. Through simulation we confirmed the precise of Geant4 again. The depth dose distribution of the inside radiation was calculated to get more information about the space environment inside shielding. As a conclusion, both with GCR proton and alpha particle there is no obvious decrease of dose with Al shielding, however, SPE spectrum does weaken as it has different energy distribution. We calculated the skin dose under different shielding thickness of 1972 SPE, obvious dose decrease was attained with increase shielding thickness.
