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RSS2005 Vol. 17, No. 09
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2005,
17.
Abstract:
By using a modified damage function model in which the dynamic failure of shocked matter was analogous to a percolation process and a stress release function which was proposed to describe the void coalescence behavior based on the percolation critical theory, the mechanical behavior and spallation of pure aluminum subjected to intense laser irradiation were studied. The laser-driven shock loading was a Gaussian pressure pulse applied at the front surface of the sample. Simulation results indicate that the mechanical response and the wave propagation strongly depend on the damage evolution, which fits the experimental observations very well, which confirms the capability of the damage function model for describing the damage evolution in ductile metals. The damage evolution and damage dist
By using a modified damage function model in which the dynamic failure of shocked matter was analogous to a percolation process and a stress release function which was proposed to describe the void coalescence behavior based on the percolation critical theory, the mechanical behavior and spallation of pure aluminum subjected to intense laser irradiation were studied. The laser-driven shock loading was a Gaussian pressure pulse applied at the front surface of the sample. Simulation results indicate that the mechanical response and the wave propagation strongly depend on the damage evolution, which fits the experimental observations very well, which confirms the capability of the damage function model for describing the damage evolution in ductile metals. The damage evolution and damage dist
2005,
17.
Abstract:
Based on conventional optical current sensor, a new measuring technology of optical current sensor with four paths was put forward. As its four output signals were accurately able to obtain the azimuth of polarization, the measuring scope of current was out control of the monotone zone of sine function and was enlarged. In order to assist optical current sensor with four paths, a new experimental data processing method with arc-tangential function was introduced. As it didn't exist insensitive zone and was able to correct the drawback of original data, it could enhance measuring precision. The whole current which was shutter's short circuit through the magneto-optical sensing element with 14 times was measured at 4.5 kV voltage and 50 μF capacity. In agree with theoretical calculation val
Based on conventional optical current sensor, a new measuring technology of optical current sensor with four paths was put forward. As its four output signals were accurately able to obtain the azimuth of polarization, the measuring scope of current was out control of the monotone zone of sine function and was enlarged. In order to assist optical current sensor with four paths, a new experimental data processing method with arc-tangential function was introduced. As it didn't exist insensitive zone and was able to correct the drawback of original data, it could enhance measuring precision. The whole current which was shutter's short circuit through the magneto-optical sensing element with 14 times was measured at 4.5 kV voltage and 50 μF capacity. In agree with theoretical calculation val
2005,
17.
Abstract:
Based on dimensional analytic theory and non-dimensionalized thermo-mechanical coupling equations for high energy laser beam irradiation, this paper presents the similarity criterion and the scaling law for thermo-mechanical coupling effect induced by high energy laser beam under some reasonably approximation conditions. The similarity criterion and the scaling law are independent of material properties related to temperature. The finite element analysis models of full scale and scale down pressurized cylindrical shells irradiated by intense laser beam are established respectively. The numerical results show similarity between the full scale and scale down models. It is concluded that the coupling effect of the thermal-mechanics induced by intense laser beam meets similarity rules under re
Based on dimensional analytic theory and non-dimensionalized thermo-mechanical coupling equations for high energy laser beam irradiation, this paper presents the similarity criterion and the scaling law for thermo-mechanical coupling effect induced by high energy laser beam under some reasonably approximation conditions. The similarity criterion and the scaling law are independent of material properties related to temperature. The finite element analysis models of full scale and scale down pressurized cylindrical shells irradiated by intense laser beam are established respectively. The numerical results show similarity between the full scale and scale down models. It is concluded that the coupling effect of the thermal-mechanics induced by intense laser beam meets similarity rules under re
2005,
17.
Abstract:
The algorithm of a portable lidar ceilometer for cloud-base height measurement was developed. The zero-crossing of lidar return slope was considered the location of the cloud base. Since the cloud was different from the atmosphere in random noise in the slope and intensity and pulse width of the backscatter returns, the cloud base height could be determined by analyzing the difference of lidar returns carefully. The random noise could be eliminated by detecting cloud continuously on the same location. The measured data by portable lidar ceilometer were compared with that by traditional count ceilomenter and they agreed well.
The algorithm of a portable lidar ceilometer for cloud-base height measurement was developed. The zero-crossing of lidar return slope was considered the location of the cloud base. Since the cloud was different from the atmosphere in random noise in the slope and intensity and pulse width of the backscatter returns, the cloud base height could be determined by analyzing the difference of lidar returns carefully. The random noise could be eliminated by detecting cloud continuously on the same location. The measured data by portable lidar ceilometer were compared with that by traditional count ceilomenter and they agreed well.
2005,
17.
Abstract:
From the Huygens-Fresnel principle, an integral expression with the chromatic aberration was obtained of the field amplitude of a beam with a shape of a quarter of a circle. From the integral expression amplitude expressions of the coherent addition field of four such subbeams with different phase delay were acquired and a mathematic model of the field in the far field was set up. Numerical modulation was carried out for a 1 ps ultrashort pulse with a 10 cm aperture and 200 cm focal length. The far-field intensity distributions of three cases were given including single beam, four beams without phase delay and four beams with a phase delay of π between them. The conclusion is that the far-field pattern of a beam with a shape of a quarter of a circle is no more centrosymmetric but axis sym
From the Huygens-Fresnel principle, an integral expression with the chromatic aberration was obtained of the field amplitude of a beam with a shape of a quarter of a circle. From the integral expression amplitude expressions of the coherent addition field of four such subbeams with different phase delay were acquired and a mathematic model of the field in the far field was set up. Numerical modulation was carried out for a 1 ps ultrashort pulse with a 10 cm aperture and 200 cm focal length. The far-field intensity distributions of three cases were given including single beam, four beams without phase delay and four beams with a phase delay of π between them. The conclusion is that the far-field pattern of a beam with a shape of a quarter of a circle is no more centrosymmetric but axis sym
2005,
17.
Abstract:
On the basis of Talbot effect of Ronchi grating, the influence of temperature on the stability of the measuring system of long focal length has been theoretically analyzed. It has been testified by experiment that the fluctuation of refractive index of atmosphere resulted from the interior and exterior temperature of the system influences the measuring precision. After taking some methods such as reducing the surface-temperature of He-Ne laser in the measuring system by water-circulation, removing the cold and heat source of the exterior, putting the couple-grating into heat insulation, the repeatability precision of the measuring system increases by 5 to 8 times. Standard error of 0.1‰ is achieved, and data fluctuation of repetitive measurement is within 5mm.
On the basis of Talbot effect of Ronchi grating, the influence of temperature on the stability of the measuring system of long focal length has been theoretically analyzed. It has been testified by experiment that the fluctuation of refractive index of atmosphere resulted from the interior and exterior temperature of the system influences the measuring precision. After taking some methods such as reducing the surface-temperature of He-Ne laser in the measuring system by water-circulation, removing the cold and heat source of the exterior, putting the couple-grating into heat insulation, the repeatability precision of the measuring system increases by 5 to 8 times. Standard error of 0.1‰ is achieved, and data fluctuation of repetitive measurement is within 5mm.
2005,
17.
Abstract:
According to the incidence angular factor of the laser beam, the locations of the laser setup above the ground are classified. The methods of geometrical analysis and numerical simulation are used. It is indicated that when a focused laser beam heats a flying cylinder, for the sake of the best heating effect, as to achieve enough heating power level and energy level at the same time, the trajectory point when the laser beam can irradiate the cylinder perpendicularly should be selected as the heating center, the effective work time of the laser should be regarded as the heating time range, and the laser setup should be placed at a proper distance from the cylinder at the very trajectory point. It is found that the problem of effect of relative position between laser setup and trajectory on
According to the incidence angular factor of the laser beam, the locations of the laser setup above the ground are classified. The methods of geometrical analysis and numerical simulation are used. It is indicated that when a focused laser beam heats a flying cylinder, for the sake of the best heating effect, as to achieve enough heating power level and energy level at the same time, the trajectory point when the laser beam can irradiate the cylinder perpendicularly should be selected as the heating center, the effective work time of the laser should be regarded as the heating time range, and the laser setup should be placed at a proper distance from the cylinder at the very trajectory point. It is found that the problem of effect of relative position between laser setup and trajectory on
2005,
17.
Abstract:
The stability of the switch pulse generator output will influence the reliability of large aperture electro-optic switch synchronizing with the laser pulse. The drift and jitter of the output pulse are important parameters of the stability. The experiments and analyses based on homemade VE-4073 thyratron show that the combined effects of DC heating thyratron and two-pulse triggering technique can greatly reduce the drift and jitter of the pulser output. The output drift of the switch pulse generator depending on these techniques is less than 6.1 ns in 48 h.
The stability of the switch pulse generator output will influence the reliability of large aperture electro-optic switch synchronizing with the laser pulse. The drift and jitter of the output pulse are important parameters of the stability. The experiments and analyses based on homemade VE-4073 thyratron show that the combined effects of DC heating thyratron and two-pulse triggering technique can greatly reduce the drift and jitter of the pulser output. The output drift of the switch pulse generator depending on these techniques is less than 6.1 ns in 48 h.
2005,
17.
Abstract:
Effects of wet-etching with four kinds of etching solution on the surface of K9 optical components were examined. By investigating the change pattern of wet-etching rate at different depth and surface parameters before and after corrosion, the depth of polishing redeposition layer was estimated. When etched to the depth of 600 nm, the loose polishing redeposition layer and the subsurface damage of the optics were mostly removed, hence the laser damage threshold was improved. However,with 1 500 nm in etching depth, the subsurface flaws and cracks appeared which lowered the laser damage threshold of the optics.The result shows that certain solution etches K9 optics with controllable rate and the laser damage threshold of the optics is improved.
Effects of wet-etching with four kinds of etching solution on the surface of K9 optical components were examined. By investigating the change pattern of wet-etching rate at different depth and surface parameters before and after corrosion, the depth of polishing redeposition layer was estimated. When etched to the depth of 600 nm, the loose polishing redeposition layer and the subsurface damage of the optics were mostly removed, hence the laser damage threshold was improved. However,with 1 500 nm in etching depth, the subsurface flaws and cracks appeared which lowered the laser damage threshold of the optics.The result shows that certain solution etches K9 optics with controllable rate and the laser damage threshold of the optics is improved.
2005,
17.
Abstract:
1.06 μm CW-Nd:YAG laser with different intensity was used to irradiate TiO2/SiO2/K9 film component, and the temperature rise of the film surface with time was measured by thermal MP575. A program was used to calculate the temperature field of laser with different intensity. Comparing experimental data with numerical simulation result, temperature change of film component with laser intensity and time were gained. The highest temperature was on the surface of film and the lowest on the surface of substrate in the direction of thickness, and the highest in the central of laser facular, the lowest at the edge in the radial direction.
1.06 μm CW-Nd:YAG laser with different intensity was used to irradiate TiO2/SiO2/K9 film component, and the temperature rise of the film surface with time was measured by thermal MP575. A program was used to calculate the temperature field of laser with different intensity. Comparing experimental data with numerical simulation result, temperature change of film component with laser intensity and time were gained. The highest temperature was on the surface of film and the lowest on the surface of substrate in the direction of thickness, and the highest in the central of laser facular, the lowest at the edge in the radial direction.
2005,
17.
Abstract:
In order to resolve the maneuvering problem in target tracking, an algorithm based on interacting multiple model(IMM) method was presented. In this method every sub-model has its own model match probability that changes with the target's estimated state and measures. The sub-model can soft-jump between each other under the control of Markovian switching coefficients. From simulation it can be seen that the IMM method can improve the tracking accuracy of maneuvering targets.
In order to resolve the maneuvering problem in target tracking, an algorithm based on interacting multiple model(IMM) method was presented. In this method every sub-model has its own model match probability that changes with the target's estimated state and measures. The sub-model can soft-jump between each other under the control of Markovian switching coefficients. From simulation it can be seen that the IMM method can improve the tracking accuracy of maneuvering targets.
2005,
17.
Abstract:
In particle measurement, in-line holography is widely used. The main advantage is that the setup is very simple, and the reconstruction process is convenient. The process of particle measurement using digital holography was numerically simulated. Two different numerical methods, direct Fourier transform algorithm and convolution algorithm, were analyzed and compared. It is shown that the convolution algorithm tallies with the practice requirement. The spatial spectra of the recorded image and its requirement for sampling frequency of the image are analyzed, from which the smallest recording distance under certain wavelength and sampling interval is obained. For an image with 512×512 pixels, if the size of one pixel is 6.7 μm and the wavelength is 532 nm, the minimum distance is 43.2 mm.
In particle measurement, in-line holography is widely used. The main advantage is that the setup is very simple, and the reconstruction process is convenient. The process of particle measurement using digital holography was numerically simulated. Two different numerical methods, direct Fourier transform algorithm and convolution algorithm, were analyzed and compared. It is shown that the convolution algorithm tallies with the practice requirement. The spatial spectra of the recorded image and its requirement for sampling frequency of the image are analyzed, from which the smallest recording distance under certain wavelength and sampling interval is obained. For an image with 512×512 pixels, if the size of one pixel is 6.7 μm and the wavelength is 532 nm, the minimum distance is 43.2 mm.
2005,
17.
Abstract:
The aluminium modulation target used to study the Rayleigh-Taylor instability in the resolved experiments of Inertial Confined Fusion (ICF) was fabricated. Based on semiconductor photolithography technology and chemical wet etching process, the stripe pattern of line width 25 μm on aluminium foil surface was obtained. The effects of the reaction conditions on the etching rate were studied. The pattern topography and the surface constituent were measured and analyzed. Aluminium modulation targets of about 32 μm thick were prepared and the etching depth reached up to 20 μm.
The aluminium modulation target used to study the Rayleigh-Taylor instability in the resolved experiments of Inertial Confined Fusion (ICF) was fabricated. Based on semiconductor photolithography technology and chemical wet etching process, the stripe pattern of line width 25 μm on aluminium foil surface was obtained. The effects of the reaction conditions on the etching rate were studied. The pattern topography and the surface constituent were measured and analyzed. Aluminium modulation targets of about 32 μm thick were prepared and the etching depth reached up to 20 μm.
2005,
17.
Abstract:
A new kind of depolarizer consisting of three parts(one is canted quartz crystal and the other two are canted fused quartz glasses) is designed. Two such depolarizers are used together (the principal axis of the second are at 45° to that of the first one) to depolarize the incident linear-polarized light. The depolarizing result is observed not only by birefringent prism and an infra-sensitive card but also a polar analyst, and in both ways results of good depolarized light are observed. And the depolarizing result is insensitive to polarizing direction of the incident light.
A new kind of depolarizer consisting of three parts(one is canted quartz crystal and the other two are canted fused quartz glasses) is designed. Two such depolarizers are used together (the principal axis of the second are at 45° to that of the first one) to depolarize the incident linear-polarized light. The depolarizing result is observed not only by birefringent prism and an infra-sensitive card but also a polar analyst, and in both ways results of good depolarized light are observed. And the depolarizing result is insensitive to polarizing direction of the incident light.
2005,
17.
Abstract:
In this paper Fe/Al alloy thin films were fabricated by pulse laser deposition(PLD), and the crystal phase, structure and micro-strain were studied. The deposition rate of films decreased with the increasing substrate temperature. The AFM pictures show that the films are compact and smooth. ICP (inductively coupled plasma) result of sample fabricated at 573 K substrate temperature shows Fe/Al atomic ratio is 1∶1. The X-ray diffraction results indicate that the crystal is Al0.5Fe0.5 with simple cube structure, the lattice constant is 0.297 nm, the average size of grains is 81.74 nm, and the average micro-distortion is 0.007 6. All above indicate that Al0.5Fe0.5 fabricated by PLD at 573 K has good crystallinity.
In this paper Fe/Al alloy thin films were fabricated by pulse laser deposition(PLD), and the crystal phase, structure and micro-strain were studied. The deposition rate of films decreased with the increasing substrate temperature. The AFM pictures show that the films are compact and smooth. ICP (inductively coupled plasma) result of sample fabricated at 573 K substrate temperature shows Fe/Al atomic ratio is 1∶1. The X-ray diffraction results indicate that the crystal is Al0.5Fe0.5 with simple cube structure, the lattice constant is 0.297 nm, the average size of grains is 81.74 nm, and the average micro-distortion is 0.007 6. All above indicate that Al0.5Fe0.5 fabricated by PLD at 573 K has good crystallinity.
2005,
17.
Abstract:
Theoretical study of Ne-like X-ray laser may provide insight into the Ni-like X-ray laser. A series of TCE (transient collisional excitation) Ne-like Ge X-ray laser experiments driven by 2ω1ω pulses were designed and the Ne-like Ge 19.6 nm X-ray laser produced in this way was modeled with the newly developed code series. The plasma status in the gain region was presented and the characteristics of the X-ray laser compared to that of the X-ray laser driven by the 1ω1ω driving scheme was given.
Theoretical study of Ne-like X-ray laser may provide insight into the Ni-like X-ray laser. A series of TCE (transient collisional excitation) Ne-like Ge X-ray laser experiments driven by 2ω1ω pulses were designed and the Ne-like Ge 19.6 nm X-ray laser produced in this way was modeled with the newly developed code series. The plasma status in the gain region was presented and the characteristics of the X-ray laser compared to that of the X-ray laser driven by the 1ω1ω driving scheme was given.
2005,
17.
Abstract:
This paper discussed the influence of the pertinence of two couples of physical parameters on the uncertainty of particle velocity and the shock pressure of test sample. The influence was estimated from calculation of experimental data. By a great deal of experimental statistic data, the influence of the pertinence of Hugoniot parameters on the uncertainty of particle velocity was less than 0.7‰, and the influence of the pertinence of physical parameters shock velocity and particle velocity on the uncertainty of shock pressure was about 0.5% .
This paper discussed the influence of the pertinence of two couples of physical parameters on the uncertainty of particle velocity and the shock pressure of test sample. The influence was estimated from calculation of experimental data. By a great deal of experimental statistic data, the influence of the pertinence of Hugoniot parameters on the uncertainty of particle velocity was less than 0.7‰, and the influence of the pertinence of physical parameters shock velocity and particle velocity on the uncertainty of shock pressure was about 0.5% .
2005,
17.
Abstract:
A scanning Hartmann inspection apparatus has been developed on the basis of the traditional Hartmann test principle. It can inspect large-aperture focusing lenses up to 300 mm in diameter within the full aperture. The apparatus consists of a large-aperture collimator, a scanning Hartmann screen, a focusing lens to be tested, a CCD camera and a computer. The longitudinal aberration and the encircled energy of the aspheric collimating lens of the Fizeau plane interferometer with the effective aperture of 154 mm are measured, and it is tested by a WＹＫＯ interferometer as well. The results obtained from the two above mentioned methods agree well, which proves that the scanning Hartmann inspection apparatus is reliable.
A scanning Hartmann inspection apparatus has been developed on the basis of the traditional Hartmann test principle. It can inspect large-aperture focusing lenses up to 300 mm in diameter within the full aperture. The apparatus consists of a large-aperture collimator, a scanning Hartmann screen, a focusing lens to be tested, a CCD camera and a computer. The longitudinal aberration and the encircled energy of the aspheric collimating lens of the Fizeau plane interferometer with the effective aperture of 154 mm are measured, and it is tested by a WＹＫＯ interferometer as well. The results obtained from the two above mentioned methods agree well, which proves that the scanning Hartmann inspection apparatus is reliable.
2005,
17.
Abstract:
Experiment of the double-clad erbium-ytterbium co-doped fiber amplifiers were discussed. This fiber with hexagonal inner clad is utilized as gain medium to amplify femtosecond pulse, which is pumped by LD with pigtail fiber. The signal with 10.8 mW average power at 20.84 MHz repetition rate is amplified to 176 mW by using 50 cm long fiber when launched pumping power is 2.5 W. The gain is 12.2 dB and the single pulse energy is 8.1 nJ. The amplified pulse width is 480 fs, corresponding to a peak power of 16 kW.
Experiment of the double-clad erbium-ytterbium co-doped fiber amplifiers were discussed. This fiber with hexagonal inner clad is utilized as gain medium to amplify femtosecond pulse, which is pumped by LD with pigtail fiber. The signal with 10.8 mW average power at 20.84 MHz repetition rate is amplified to 176 mW by using 50 cm long fiber when launched pumping power is 2.5 W. The gain is 12.2 dB and the single pulse energy is 8.1 nJ. The amplified pulse width is 480 fs, corresponding to a peak power of 16 kW.
2005,
17.
Abstract:
According to Raoult's law and Dalton's partial-pressure laws, the mixture of D2, T2 and DT fuel components in the proportion of 3∶3∶4 in an ICF target is analyzed on the basis of mass conservation, under the vapor-liquid equilibrium phase at several work temperatures (22, 24, 26, 28 and 30 K).The result is that at 22 K, with filling pressure increasing from 1 MPa to 5 MPa, the mole fraction of D2 increases from 0.251 to 0.290, the mole fraction of T2 decreases from 0.350 to 0.310 in the liquid fuel, and the mole fraction of D2 increases from 0.322 to 0.365, the mole fraction of T2 decreases from 0.278 to 0.241 in the gas fuel. When filling pressure is 5 MPa, with work temperature increasing from 22 K to 30 K, the mole fraction of D2 decreases from 0.290 to 0.261, the mole fraction of T2
According to Raoult's law and Dalton's partial-pressure laws, the mixture of D2, T2 and DT fuel components in the proportion of 3∶3∶4 in an ICF target is analyzed on the basis of mass conservation, under the vapor-liquid equilibrium phase at several work temperatures (22, 24, 26, 28 and 30 K).The result is that at 22 K, with filling pressure increasing from 1 MPa to 5 MPa, the mole fraction of D2 increases from 0.251 to 0.290, the mole fraction of T2 decreases from 0.350 to 0.310 in the liquid fuel, and the mole fraction of D2 increases from 0.322 to 0.365, the mole fraction of T2 decreases from 0.278 to 0.241 in the gas fuel. When filling pressure is 5 MPa, with work temperature increasing from 22 K to 30 K, the mole fraction of D2 decreases from 0.290 to 0.261, the mole fraction of T2
2005,
17.
Abstract:
Based on quasi-relativistic distorted wave Born approximation with exchange, the electron impact excitation cross sections between configurations of H-, He-, and Li-like argon ion were calculated systemically and compared with previous theoretical predictions. Most of the present calculated results agreed within deviation of 10% with the theoretical results of full relativistic distorted wave method, and agreed in general within deviation of 15% with those of closing coupling methods except that in the low incident energy, there were relatively larger deviations due to the present calculation considering only the direct excitation processes while the resonance effects were not taken into account. The codes presented in this paper can conveniently provide a large amount of atomic data for p
Based on quasi-relativistic distorted wave Born approximation with exchange, the electron impact excitation cross sections between configurations of H-, He-, and Li-like argon ion were calculated systemically and compared with previous theoretical predictions. Most of the present calculated results agreed within deviation of 10% with the theoretical results of full relativistic distorted wave method, and agreed in general within deviation of 15% with those of closing coupling methods except that in the low incident energy, there were relatively larger deviations due to the present calculation considering only the direct excitation processes while the resonance effects were not taken into account. The codes presented in this paper can conveniently provide a large amount of atomic data for p
2005,
17.
Abstract:
Hydrogen (deuterium) gas discharge source was used to bombard target of non-crystalloid deuterate polyethylene polymethylmethacrylate, etc. The scattering spectrum was measured. There are several sharp X-ray spectral lines on the scattering spectrum, but the primary spectrum of the discharge does not include these lines of the scattering spectrum. It is confirmed that they are neither the characteristic X-ray of C, O or other possible impurity element, nor diffractive spectral lines, nor the “absorption cut off” of electron bremsstrahlung spectrum. It is most likely that they are a kind of X-ray spectral series of new kind of atom state. A new theory model called small hydrogen atom was put forward to explain the spectrum. It assumes that the discharge of hydrogen gas will produce small
Hydrogen (deuterium) gas discharge source was used to bombard target of non-crystalloid deuterate polyethylene polymethylmethacrylate, etc. The scattering spectrum was measured. There are several sharp X-ray spectral lines on the scattering spectrum, but the primary spectrum of the discharge does not include these lines of the scattering spectrum. It is confirmed that they are neither the characteristic X-ray of C, O or other possible impurity element, nor diffractive spectral lines, nor the “absorption cut off” of electron bremsstrahlung spectrum. It is most likely that they are a kind of X-ray spectral series of new kind of atom state. A new theory model called small hydrogen atom was put forward to explain the spectrum. It assumes that the discharge of hydrogen gas will produce small
2005,
17.
Abstract:
According to the design and the principle of the ffner stretcher, the pulse stretcher for OPCPA laser system was experimentally investigated. Using the numerical method, the four key parameters were appropriately selected, that is the angle of incidence being 51.05°, the distance from grating to concave spherical mirror being 653 mm, the curvature radius of the concave spherical mirror being 1 000 mm and the grating constant being 1 800 lines/mm. The experimental results demonstrate that an expansion of 30 fs to 545 ps pulse and a stretching ratio of 18,167 can be obtained by adjusting the key parameters.
According to the design and the principle of the ffner stretcher, the pulse stretcher for OPCPA laser system was experimentally investigated. Using the numerical method, the four key parameters were appropriately selected, that is the angle of incidence being 51.05°, the distance from grating to concave spherical mirror being 653 mm, the curvature radius of the concave spherical mirror being 1 000 mm and the grating constant being 1 800 lines/mm. The experimental results demonstrate that an expansion of 30 fs to 545 ps pulse and a stretching ratio of 18,167 can be obtained by adjusting the key parameters.
2005,
17.
Abstract:
The fabrication process of Al/Cu impedance-match EOS measurement target was discussed. With the rolling and diffusion-bonding technologies, the Al/Cu impedance-match EOS measurement target was successfully fabricated. The structure and surface roughness of the target were analyzed by AFM, SEM, XRD, and alpha-step 500 device. The surface roughness of the target is smaller than 25 nm. And the Al/Cu diffusion interface zone is narrower than 150 nm.
The fabrication process of Al/Cu impedance-match EOS measurement target was discussed. With the rolling and diffusion-bonding technologies, the Al/Cu impedance-match EOS measurement target was successfully fabricated. The structure and surface roughness of the target were analyzed by AFM, SEM, XRD, and alpha-step 500 device. The surface roughness of the target is smaller than 25 nm. And the Al/Cu diffusion interface zone is narrower than 150 nm.
2005,
17.
Abstract:
This paper introduces the electroless plating technique to fabricate integral Cu hohlraum on the surface of pretreated PMMA axis. Some parameters effect on the deposition rate and solution stability, such as the CuSO4 content, reducing agent content, pH value and temperature were studied. The optimized mass concentration of CuSO4 is 10~20 g/L, TART·K·Na is 10~30 g/L, EDTA·2Na is 10~28 g/L, additive is 10 mg/L, the volumic concetration of HCHO is 10~25 mL/L, pH value is 12~13, and the base temperature is 35~65 ℃. The feasible technics of electroless Cu plating are confirmed base on experimental result. According to the technics, Cu hohlraum with thickness of 10～25 μm was obtained and there were not flaw and indentations on the surface. After the axis was removed by chemical etching, t
This paper introduces the electroless plating technique to fabricate integral Cu hohlraum on the surface of pretreated PMMA axis. Some parameters effect on the deposition rate and solution stability, such as the CuSO4 content, reducing agent content, pH value and temperature were studied. The optimized mass concentration of CuSO4 is 10~20 g/L, TART·K·Na is 10~30 g/L, EDTA·2Na is 10~28 g/L, additive is 10 mg/L, the volumic concetration of HCHO is 10~25 mL/L, pH value is 12~13, and the base temperature is 35~65 ℃. The feasible technics of electroless Cu plating are confirmed base on experimental result. According to the technics, Cu hohlraum with thickness of 10～25 μm was obtained and there were not flaw and indentations on the surface. After the axis was removed by chemical etching, t
2005,
17.
Abstract:
Under the circumstance of oversize coaxial waveguide, the traditional coaxial mode converter with four metal plates inserted does not satisfy the unique-mode requirement. In this paper, an oversize mode converter is designed with eight metal plates inserted. Moreover, it combines with a coaxial horn to form a mode-transducing antenna, which can directly radiate coaxial TEM mode from high-power microwave sources. The center frequency is 7 GHz. The calculated results of the antenna are as follows: the antenna gain is 22.2 dB with an aperture efficiency of 53.7%, the reflection coefficient is 0.07 at the center frequency and less than 0.3 in the range of 6.5~7.5 GHz. The measured results are as follows: the antenna gain is 21.5 dB with an aperture efficiency of about 46%, the reflection coeff
Under the circumstance of oversize coaxial waveguide, the traditional coaxial mode converter with four metal plates inserted does not satisfy the unique-mode requirement. In this paper, an oversize mode converter is designed with eight metal plates inserted. Moreover, it combines with a coaxial horn to form a mode-transducing antenna, which can directly radiate coaxial TEM mode from high-power microwave sources. The center frequency is 7 GHz. The calculated results of the antenna are as follows: the antenna gain is 22.2 dB with an aperture efficiency of 53.7%, the reflection coefficient is 0.07 at the center frequency and less than 0.3 in the range of 6.5~7.5 GHz. The measured results are as follows: the antenna gain is 21.5 dB with an aperture efficiency of about 46%, the reflection coeff
2005,
17.
Abstract:
It is a new technology to apply an ECR ion source to the neutron generator. Because of the structure limitation, working state of the ECR ion source could not be judged by the color of gas discharging in discharge chamber. Therefore, it was hard to estimate if the ECR ion source was working properly in the neutron generator. The method to resolve the problem was described in this paper. The microwave power was measured on-ine by a directional coupler and a small microwave power meter. The ion beam current could be educed from the measured incidence microwave power, and discharge state in discharge chamber could be determined.
It is a new technology to apply an ECR ion source to the neutron generator. Because of the structure limitation, working state of the ECR ion source could not be judged by the color of gas discharging in discharge chamber. Therefore, it was hard to estimate if the ECR ion source was working properly in the neutron generator. The method to resolve the problem was described in this paper. The microwave power was measured on-ine by a directional coupler and a small microwave power meter. The ion beam current could be educed from the measured incidence microwave power, and discharge state in discharge chamber could be determined.
2005,
17.
Abstract:
The principle of the method based on reflectance phase for calculating the Qext of cavities is analyzed and the differences between the ideal coupling circuit used in the method and the practical equivalent circuit are pointed out in this paper. Firstly, the transmission line couples with a cavity by only partial inductance in the practical circuit. Secondly, there are coupling slots in π mode double-gap cavity. These two differences will bring on failure of the method in calculating the Qext of cavities. Quantitatively, the calculation results show that, if the ratio of the coupling inductance to the non-coupling inductance is smaller than 0.1, or the resonant frequency of the coupling slots is smaller than the 2π mode frequency of a double-gap cavity, the method based on reflectance ph
The principle of the method based on reflectance phase for calculating the Qext of cavities is analyzed and the differences between the ideal coupling circuit used in the method and the practical equivalent circuit are pointed out in this paper. Firstly, the transmission line couples with a cavity by only partial inductance in the practical circuit. Secondly, there are coupling slots in π mode double-gap cavity. These two differences will bring on failure of the method in calculating the Qext of cavities. Quantitatively, the calculation results show that, if the ratio of the coupling inductance to the non-coupling inductance is smaller than 0.1, or the resonant frequency of the coupling slots is smaller than the 2π mode frequency of a double-gap cavity, the method based on reflectance ph
2005,
17.
Abstract:
To improve the output spectrum of magnetron and make simulated model near to the practical structure, considering the practical structure of the permanent magnet and soft magnet, the magnetic field system of microwave oven magnetrons was modeled and simulated using MAFIA. The radial non-uniform magnetic field distribution is obtained. The longitudinal magnetic field is increasing along the radial direction in the anode cavity. The trend is consistent with the experimental data. In the condition of the radial non-uniform magnetic field, the cavity hot-test simulation is done to obtain the π mode frequency 2.437 GHz. Compared with oven's work frequency 2.450 GHz, the relatively error is 0.5%. The remarkable improvement is achieved in suppressing the RF harmonic content, making the radiaton
To improve the output spectrum of magnetron and make simulated model near to the practical structure, considering the practical structure of the permanent magnet and soft magnet, the magnetic field system of microwave oven magnetrons was modeled and simulated using MAFIA. The radial non-uniform magnetic field distribution is obtained. The longitudinal magnetic field is increasing along the radial direction in the anode cavity. The trend is consistent with the experimental data. In the condition of the radial non-uniform magnetic field, the cavity hot-test simulation is done to obtain the π mode frequency 2.437 GHz. Compared with oven's work frequency 2.450 GHz, the relatively error is 0.5%. The remarkable improvement is achieved in suppressing the RF harmonic content, making the radiaton
2005,
17.
Abstract:
Winding coil on primary side of the ferrite toroid forms an inductor. The permeability of the ferrite changes with various biasing DC current in coils on secondary side of the ferrite. Thus the inductance of the ferrite changes correspondingly. In the process of designing RF cavity of CSR，ferrite is used for the loading material of cavity. The characteristic of ferrite directly determinds whether the cavity can meet the requirements of the product design or not. The impedance of the cavity decides how much RF power should be got. At the same time, the impedance is in direct proportion to the μQf. Obviously the measurement of ferrite material is very important. This paper presents the measurement principle of permeability and Q-factor of ferrite, it also gives the concrete circuit and res
Winding coil on primary side of the ferrite toroid forms an inductor. The permeability of the ferrite changes with various biasing DC current in coils on secondary side of the ferrite. Thus the inductance of the ferrite changes correspondingly. In the process of designing RF cavity of CSR，ferrite is used for the loading material of cavity. The characteristic of ferrite directly determinds whether the cavity can meet the requirements of the product design or not. The impedance of the cavity decides how much RF power should be got. At the same time, the impedance is in direct proportion to the μQf. Obviously the measurement of ferrite material is very important. This paper presents the measurement principle of permeability and Q-factor of ferrite, it also gives the concrete circuit and res
2005,
17.
Abstract:
Particles coupling might lead to the loss of particles in some condition. This paper described that the rotation of the main magnets and the existence of the solenoid were the reasons of the particles coupling between horizontal and vertical oscillations and that the particles would be unstable when working at sum resonance and the existence of the solenoid contributed more to the particles coupling than the rotation of the main magnets. Using the typical parameters of HIRFL-CSRm system, the particles would be stable when CSRm worked at given working point which was nearly difference resonance.
Particles coupling might lead to the loss of particles in some condition. This paper described that the rotation of the main magnets and the existence of the solenoid were the reasons of the particles coupling between horizontal and vertical oscillations and that the particles would be unstable when working at sum resonance and the existence of the solenoid contributed more to the particles coupling than the rotation of the main magnets. Using the typical parameters of HIRFL-CSRm system, the particles would be stable when CSRm worked at given working point which was nearly difference resonance.
2005,
17.
Abstract:
A radial insulated diode with a high emission current density of electron-beam was introduced in this paper. As an experiment platform, the CHP01 accelerator was used to study the emission characteristics of the diode. This intense current electron-beam diode can operate steadily at the pulse repetition rate as high as 100 Hz. The beam voltage exceeds 600 kV, beam current 12 kA, pulse width 45 ns. Correspondingly the emission current density of cathode is as high as 17 kA/cm2. The characteristic impedance of diode as a function of magnetic-field was studied.
A radial insulated diode with a high emission current density of electron-beam was introduced in this paper. As an experiment platform, the CHP01 accelerator was used to study the emission characteristics of the diode. This intense current electron-beam diode can operate steadily at the pulse repetition rate as high as 100 Hz. The beam voltage exceeds 600 kV, beam current 12 kA, pulse width 45 ns. Correspondingly the emission current density of cathode is as high as 17 kA/cm2. The characteristic impedance of diode as a function of magnetic-field was studied.
2005,
17.
Abstract:
In order to attain the design beam intensity of Phase II Project of Hefei Light Source(HLS), one family of octupoles were installed in the place where vertical Batatron function is relatively large in HLS storage ring. After adding octupoles, the horizontal dynamic aperture is little affected but the vertical dynamic aperture decreased drastically. This is not detrimental to beam injection and accumulation, because the vertical dynamic aperture is still larger than physical aperture. The vertical oscillation frequency spread generated by octupoles can provide Landau damping time about several microseconds, which is very helpful to overcome vertical collective instabilities in HLS storage ring, where radiation damping time is 1.4 s. One year's operation has demonstrated the effectiveness of
In order to attain the design beam intensity of Phase II Project of Hefei Light Source(HLS), one family of octupoles were installed in the place where vertical Batatron function is relatively large in HLS storage ring. After adding octupoles, the horizontal dynamic aperture is little affected but the vertical dynamic aperture decreased drastically. This is not detrimental to beam injection and accumulation, because the vertical dynamic aperture is still larger than physical aperture. The vertical oscillation frequency spread generated by octupoles can provide Landau damping time about several microseconds, which is very helpful to overcome vertical collective instabilities in HLS storage ring, where radiation damping time is 1.4 s. One year's operation has demonstrated the effectiveness of
2005,
17.
Abstract:
The parameter of beam positions at HLS 200 MeV LINAC is very important to injection efficiency. A new strip-line beam position monitor system was designed recently, which is not interceptive to beam, qualified in precision and easy to digitalize the results. The system consists of a stripline structure and a signal processing system. The signal processing system consists of a band pass filter(BPF) with center frequency of 2.856 GHz and bandwidth of 10 MHz, a logarithmic detector, a analog digital converting module, and a data acquisition program based on Labview. The signal processing system takes advantage of the virtual instrument (VI) technique, which is open, modularized, interactive and expandable. The signal processing system has a resolution of 0.1 mm and meets the design requiremen
The parameter of beam positions at HLS 200 MeV LINAC is very important to injection efficiency. A new strip-line beam position monitor system was designed recently, which is not interceptive to beam, qualified in precision and easy to digitalize the results. The system consists of a stripline structure and a signal processing system. The signal processing system consists of a band pass filter(BPF) with center frequency of 2.856 GHz and bandwidth of 10 MHz, a logarithmic detector, a analog digital converting module, and a data acquisition program based on Labview. The signal processing system takes advantage of the virtual instrument (VI) technique, which is open, modularized, interactive and expandable. The signal processing system has a resolution of 0.1 mm and meets the design requiremen
2005,
17.
Abstract:
Two kinds of self-breakdown water switches with different configurations for Qiangguang-I accelerator were described. The electrical model of the water switch was built. By estimation and Pspice calculation, the parameters of the switches were determined. The acquired breakdown characteristics of the two different switches by experiments were described by two different breakdown models. The critical field of the transfer switch could be calculated by J. C. Martin empirical expression about water breakdown with a mostly uniform field. The critical field of the output switch could be calculated by J. C. Martin expression about divergent field of point-plane electrodes. The experimental data of breakdown of water switch show that the above-mentioned methods for breakdown field calculation are
Two kinds of self-breakdown water switches with different configurations for Qiangguang-I accelerator were described. The electrical model of the water switch was built. By estimation and Pspice calculation, the parameters of the switches were determined. The acquired breakdown characteristics of the two different switches by experiments were described by two different breakdown models. The critical field of the transfer switch could be calculated by J. C. Martin empirical expression about water breakdown with a mostly uniform field. The critical field of the output switch could be calculated by J. C. Martin expression about divergent field of point-plane electrodes. The experimental data of breakdown of water switch show that the above-mentioned methods for breakdown field calculation are
2005,
17.
Abstract:
The photomultiplier tube (PMT) responding to direct neutron irradiation has an extreme effect on the scintillation detector design and its practical applications. The response mechanism of a photomultiplier tube interacting with an accelerator neutron source was investigated. 10B(n,α), 28Si(n,α） and 28Si(n,p) reactions in borosilicate glass of the end window lead to fluorescence yield, and then the fluorescence was converted into electrons by the photocathode. Experiments were carried out with EMI photomultiplier tubes (9815B and 9850B) at 5SDH-2 accelerator and the responses to neutrons with neutron energy ranging between 0.5 MeV and 5 MeV were obtained. The results show that the spectral sensitivities increase with the incident neutron energy. The sensitivity ratio of 9815B to 9850B i
The photomultiplier tube (PMT) responding to direct neutron irradiation has an extreme effect on the scintillation detector design and its practical applications. The response mechanism of a photomultiplier tube interacting with an accelerator neutron source was investigated. 10B(n,α), 28Si(n,α） and 28Si(n,p) reactions in borosilicate glass of the end window lead to fluorescence yield, and then the fluorescence was converted into electrons by the photocathode. Experiments were carried out with EMI photomultiplier tubes (9815B and 9850B) at 5SDH-2 accelerator and the responses to neutrons with neutron energy ranging between 0.5 MeV and 5 MeV were obtained. The results show that the spectral sensitivities increase with the incident neutron energy. The sensitivity ratio of 9815B to 9850B i
