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RSS2009 Vol. 21, No. 10
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2009,
21.
Abstract:
A diffuser reflection method for laser beam power/energy measurement is proposed. Using the Lambert character of the diffuser, according to the definition of BRDF, through the reflect signal measurement, the power/energy of the laser incident on the diffuser can be achieved. In practice, on the basis of laboratory calibration, the power/energy standard is transferred into the diffuser-detector system, then the calibrated system is utilized to realized laser power/energy measurement in the field. The uncertainty analysis shows that uncertainty of the measurement is less than 10%, the method can greatly improve the accuracy of far-field spot power/energy measurement.
A diffuser reflection method for laser beam power/energy measurement is proposed. Using the Lambert character of the diffuser, according to the definition of BRDF, through the reflect signal measurement, the power/energy of the laser incident on the diffuser can be achieved. In practice, on the basis of laboratory calibration, the power/energy standard is transferred into the diffuser-detector system, then the calibrated system is utilized to realized laser power/energy measurement in the field. The uncertainty analysis shows that uncertainty of the measurement is less than 10%, the method can greatly improve the accuracy of far-field spot power/energy measurement.
2009,
21.
Abstract:
A high-power Yb3+-doped photonic crystal fiber(PCF) laser based on Fabry-Perot cavity structure was studied. The laser was two-end pumped by two pumping sources at 915 nm and 976 nm, respectively, and a single-mode continuous-wave laser of 552 W was obtained. The laser had a slope efficiency of 76% and an optical-to-optical conversion efficiency of 56%. The central wavelength of the laser was 1 078 nm and the beam quality factor was 1.2.
A high-power Yb3+-doped photonic crystal fiber(PCF) laser based on Fabry-Perot cavity structure was studied. The laser was two-end pumped by two pumping sources at 915 nm and 976 nm, respectively, and a single-mode continuous-wave laser of 552 W was obtained. The laser had a slope efficiency of 76% and an optical-to-optical conversion efficiency of 56%. The central wavelength of the laser was 1 078 nm and the beam quality factor was 1.2.
2009,
21.
Abstract:
The array CCD is irradiated by a 532 nm, 10 ns pulsed laser. According to the experiment phenomenon, hard damage process of CCD can be divided into 3 stages. In the first stage, when the CCD is irradiated by the laser with a low energy density, local white blind spots appears, which can not be recovered, while other parts of CCD can work normally. In the second stage, vertical bright white lines appear in the clock line direction of the light spot after irradiation, which can not work normally and can not be recovered by stopping irradiation. In the third stage, the CCD is damaged completely after being irradiated by the laser with a high energy density, and can not be recovered. Damaging mechanism of each stage is analyzed. Finally, aiming at the saturation and recovery stage of the CCD,
The array CCD is irradiated by a 532 nm, 10 ns pulsed laser. According to the experiment phenomenon, hard damage process of CCD can be divided into 3 stages. In the first stage, when the CCD is irradiated by the laser with a low energy density, local white blind spots appears, which can not be recovered, while other parts of CCD can work normally. In the second stage, vertical bright white lines appear in the clock line direction of the light spot after irradiation, which can not work normally and can not be recovered by stopping irradiation. In the third stage, the CCD is damaged completely after being irradiated by the laser with a high energy density, and can not be recovered. Damaging mechanism of each stage is analyzed. Finally, aiming at the saturation and recovery stage of the CCD,
2009,
21.
Abstract:
The method of spherical aberration measurement and compensation is introduced for the high power and high beam quality diode pumped Nd:YAG rod lasers. The S-H wavefront sensor is employed to measure the 3rd spherical aberration, and a compensator is designed to correct it. The overall aberrations with and without compensation are analyzed. The beam quality factor of a master-oscillator power-amplifier system is improved from 9.2 to 6.4 with spherical aberration compensation(SAC). The experiment results prove that the 3rd spherical aberration of laser rod can be eliminated by SAC without increasing other aberrations, thus improving the beam quality of lasers.
The method of spherical aberration measurement and compensation is introduced for the high power and high beam quality diode pumped Nd:YAG rod lasers. The S-H wavefront sensor is employed to measure the 3rd spherical aberration, and a compensator is designed to correct it. The overall aberrations with and without compensation are analyzed. The beam quality factor of a master-oscillator power-amplifier system is improved from 9.2 to 6.4 with spherical aberration compensation(SAC). The experiment results prove that the 3rd spherical aberration of laser rod can be eliminated by SAC without increasing other aberrations, thus improving the beam quality of lasers.
2009,
21.
Abstract:
Double and triple frequency laser outputs have been obtained with the adoption of a parallel grating-grating cavity. The results are derived at a total gas pressure of 50.7 kPa, with the gas combination in volume fraction of 13% CO2, 13% N2, 74% He under 27 kV voltage. The double or triple frequency output laser possesses fine space overlap and time synchronization, and is tunable within a wide frequency ange. The laser exports beside one of the gratings approximately parallel to the cavity axis. It can meet the requirement of some materials’ double (or multiple) frequency excitation and isotope separation.
Double and triple frequency laser outputs have been obtained with the adoption of a parallel grating-grating cavity. The results are derived at a total gas pressure of 50.7 kPa, with the gas combination in volume fraction of 13% CO2, 13% N2, 74% He under 27 kV voltage. The double or triple frequency output laser possesses fine space overlap and time synchronization, and is tunable within a wide frequency ange. The laser exports beside one of the gratings approximately parallel to the cavity axis. It can meet the requirement of some materials’ double (or multiple) frequency excitation and isotope separation.
2009,
21.
Abstract:
Based on the principle of traditional fiber laser, rate equations and the power transmission equations of the single mode photonic crystal fiber(PCF) laser are given considering the mode field distribution of PCF, and then the characteristics of the ytterbium-doped single mode PCF laser are numerically analyzed. The results show that the air filling factor of PCF does not remarkably affect the output power, pump threshold power and slope efficiency, but markedly influence the nonlinear Raman threshold of PCF laser. The PCF laser outputs signal light mainly or signal and Stokes lights simultaneously while the pump power is below or above the Raman threshold, respectively. Therefore, a concept of dual-wavelength fiber laser through controlling the pump power is presented. At the same time,
Based on the principle of traditional fiber laser, rate equations and the power transmission equations of the single mode photonic crystal fiber(PCF) laser are given considering the mode field distribution of PCF, and then the characteristics of the ytterbium-doped single mode PCF laser are numerically analyzed. The results show that the air filling factor of PCF does not remarkably affect the output power, pump threshold power and slope efficiency, but markedly influence the nonlinear Raman threshold of PCF laser. The PCF laser outputs signal light mainly or signal and Stokes lights simultaneously while the pump power is below or above the Raman threshold, respectively. Therefore, a concept of dual-wavelength fiber laser through controlling the pump power is presented. At the same time,
2009,
21.
Abstract:
Hard X-ray radiography is a technique widely used to diagnose inner information of matters. It is necessary to study the areal density(AD) resolution of hard X-ray imaging systems, because areal density is an important measurement of density, thickness and quality. In this paper, the model of AD resolution is derived and a new method of measurement for AD resolution is established. Using the self-made AD resolution plate, AD resolution limit of the hard X-ray imaging system, which is composed of scintillator, fiber bundle and CCD camera, is experimentally obtained under different exposures. Experimental data agree with the model curve in tendency, that is, the maximal AD resolution increases with the growth of the exposure, while the minimum AD resolution decreases.
Hard X-ray radiography is a technique widely used to diagnose inner information of matters. It is necessary to study the areal density(AD) resolution of hard X-ray imaging systems, because areal density is an important measurement of density, thickness and quality. In this paper, the model of AD resolution is derived and a new method of measurement for AD resolution is established. Using the self-made AD resolution plate, AD resolution limit of the hard X-ray imaging system, which is composed of scintillator, fiber bundle and CCD camera, is experimentally obtained under different exposures. Experimental data agree with the model curve in tendency, that is, the maximal AD resolution increases with the growth of the exposure, while the minimum AD resolution decreases.
2009,
21.
Abstract:
The optical degradation in ZnO white paint under low energy proton exposure was investigated in terms of slow-positron annihilation spectroscopy. Experimental results show that with increasing proton fluence, the S-parameter of the Doppler broadening spectrum gradually decreases, and the W-parameter increases. The slope plot of the fitting S-W changes under the proton exposure. The decrease of S-parameter can be attri-buted to a decrease of zinc vacancy content and the formation of quasi-positroniums. The quasi-positronium is viewed as a bounded state of a singly ionized oxygen vacancy (trapping an electron) with a positron, the formation of which could reduce the positron annihilation rate and thus the S-parameter. The decrease of S-parameter demonstrates the amount increase of singly ion
The optical degradation in ZnO white paint under low energy proton exposure was investigated in terms of slow-positron annihilation spectroscopy. Experimental results show that with increasing proton fluence, the S-parameter of the Doppler broadening spectrum gradually decreases, and the W-parameter increases. The slope plot of the fitting S-W changes under the proton exposure. The decrease of S-parameter can be attri-buted to a decrease of zinc vacancy content and the formation of quasi-positroniums. The quasi-positronium is viewed as a bounded state of a singly ionized oxygen vacancy (trapping an electron) with a positron, the formation of which could reduce the positron annihilation rate and thus the S-parameter. The decrease of S-parameter demonstrates the amount increase of singly ion
2009,
21.
Abstract:
Sc2O3 substitution layer is introduced to 532 nm high reflector(HR) of HfO2/SiO2. According to its solution in hydrochloric acid, when failure occurs, putting the optics into acid, following by the solution of Sc2O3 substitution layer, the whole films are romoved clearly, then the substrates can be repolished simply and reused, time and cost can be saved greatly, too. 0% of Sc is detected by energy diffraction spectrum after acid soaking on BK7 substrates. Lamada900 spectrophotometer, optical interferometer and WykoNT1100 contourgraph are employed to characterize the transmittance, stress and surface morphology of the 532 nm HR films, and the laser induced damage thresholds of the films with 532 nm laser beam are measured b
Sc2O3 substitution layer is introduced to 532 nm high reflector(HR) of HfO2/SiO2. According to its solution in hydrochloric acid, when failure occurs, putting the optics into acid, following by the solution of Sc2O3 substitution layer, the whole films are romoved clearly, then the substrates can be repolished simply and reused, time and cost can be saved greatly, too. 0% of Sc is detected by energy diffraction spectrum after acid soaking on BK7 substrates. Lamada900 spectrophotometer, optical interferometer and WykoNT1100 contourgraph are employed to characterize the transmittance, stress and surface morphology of the 532 nm HR films, and the laser induced damage thresholds of the films with 532 nm laser beam are measured b
2009,
21.
Abstract:
For the feasibility study of microfocus X-ray phase contrast imaging in double and multi-layer plastic microsphere imaging and analysis, the images with clear characteristics of the double-layer plastic microsphere were obtained by choosing suitable experimental parameters on the consideration of imaging magnification, resolution, contrast and other factors, and based on in-line X-ray phase contrast imaging technique. Characteristic parameters of the double-layer microsphere, including inner layer thickness of (10.5 ± 0.6) μm, outer layer thickness of (9.2 ± 0.7) μm and external diameter of (273.3 ± 1.0) μm, were obtained by the use of segmentation methods, such as the Laplacian of Gaussian edge detection used to get the edges of each layer.
For the feasibility study of microfocus X-ray phase contrast imaging in double and multi-layer plastic microsphere imaging and analysis, the images with clear characteristics of the double-layer plastic microsphere were obtained by choosing suitable experimental parameters on the consideration of imaging magnification, resolution, contrast and other factors, and based on in-line X-ray phase contrast imaging technique. Characteristic parameters of the double-layer microsphere, including inner layer thickness of (10.5 ± 0.6) μm, outer layer thickness of (9.2 ± 0.7) μm and external diameter of (273.3 ± 1.0) μm, were obtained by the use of segmentation methods, such as the Laplacian of Gaussian edge detection used to get the edges of each layer.
2009,
21.
Abstract:
In order to meet the stringent stability requirement, target area structural systemic stability design was used in the inertial confinement facilities in which National Ignition Facility（NIF）of USA and SG facility are representative. In the structural systemic stability design of the SG facility target area, a new analytical method was proposed to obtain the drifting error of each beam by accounting the dynamic responses of the optical elements. This stability evalutation method was different from that of National Ignition Facility of USA. The calculated drifting errors of the beams indicate that the designed structural system has meet the stability requirement of the SG facility target area. It is concluded that this analytical method can be used in the structural systemic stability de
In order to meet the stringent stability requirement, target area structural systemic stability design was used in the inertial confinement facilities in which National Ignition Facility（NIF）of USA and SG facility are representative. In the structural systemic stability design of the SG facility target area, a new analytical method was proposed to obtain the drifting error of each beam by accounting the dynamic responses of the optical elements. This stability evalutation method was different from that of National Ignition Facility of USA. The calculated drifting errors of the beams indicate that the designed structural system has meet the stability requirement of the SG facility target area. It is concluded that this analytical method can be used in the structural systemic stability de
2009,
21.
Abstract:
In order to study the influence of β electrons from tritium decay upon hydrogen-barrier property of hollow glass microspheres(HGMs), this paper investigates the potassium ion migration and its impact on glass structure and gas-barrier property using XPS on-site characterization. Experiments reveal that, above the threshold dose of irradiation, the hydrogen-barrier property of HGM decreases with the increase of K2O in glass due to the formation of potassium ion migration net. For given glass composition and above the threshold dose, the formation of potassium ion migration net would become easier and the hydrogen-barrier property of HGM would decrease faster with the irradiation dose increasing.
In order to study the influence of β electrons from tritium decay upon hydrogen-barrier property of hollow glass microspheres(HGMs), this paper investigates the potassium ion migration and its impact on glass structure and gas-barrier property using XPS on-site characterization. Experiments reveal that, above the threshold dose of irradiation, the hydrogen-barrier property of HGM decreases with the increase of K2O in glass due to the formation of potassium ion migration net. For given glass composition and above the threshold dose, the formation of potassium ion migration net would become easier and the hydrogen-barrier property of HGM would decrease faster with the irradiation dose increasing.
2009,
21.
Abstract:
The copper multi-step target with several to several tens of microns in thickness used in equation of state(EOS) experiment was produced by single point diamond turning(SPDT) technology. Parameters of finish process are given by rational tool design, clamp design and technical process design. The surface roughness is characterized by profile testing instrument, profilometer and white light interferometer. The results indicate that surface root mean square roughness of copper multi-step target by SPDT is less than 50 nm. The density of target material is tested by Archimedes principle. The result showed that the density of the copper mutil-step target is （8.945±0.074） g/cm3.
The copper multi-step target with several to several tens of microns in thickness used in equation of state(EOS) experiment was produced by single point diamond turning(SPDT) technology. Parameters of finish process are given by rational tool design, clamp design and technical process design. The surface roughness is characterized by profile testing instrument, profilometer and white light interferometer. The results indicate that surface root mean square roughness of copper multi-step target by SPDT is less than 50 nm. The density of target material is tested by Archimedes principle. The result showed that the density of the copper mutil-step target is （8.945±0.074） g/cm3.
2009,
21.
Abstract:
Doped acrylate monomers were synthesized through the reaction between different crylic acid and halogenated phenylic acid, and their structure were characterized with nuclear magnetic resonance and mass spectrometry. Poly doped-acrylate foams were prepared with theoretical density of 50 mg·cm-3, and the maximal mass fraction of chlorine doped was 15% doped chlorine 15%. Based on polymer gelling velocity, the polymerization of doped acrylate monomer with poly acrylate was discussed.
Doped acrylate monomers were synthesized through the reaction between different crylic acid and halogenated phenylic acid, and their structure were characterized with nuclear magnetic resonance and mass spectrometry. Poly doped-acrylate foams were prepared with theoretical density of 50 mg·cm-3, and the maximal mass fraction of chlorine doped was 15% doped chlorine 15%. Based on polymer gelling velocity, the polymerization of doped acrylate monomer with poly acrylate was discussed.
2009,
21.
Abstract:
Azimuthal X-ray power distribution has been investigated in wire-array Z-pinch plasma implosions, using ST1432 scintillator, multi-mode quartz optical fiber and photomultiplier tube with the highest linear current. The load foils used in the experiments include single tungsten array and single aluminum array. And the driving current scales from 1.5 MA to 1.8 MA while the leading-edge pulse time varies from 20 ns to 90 ns. It is shown that X-ray power does not distribute evenly. X-ray radiation at axial direction is stronger than that at radial direction for tungsten wire-array implosion, while X-ray radiation at radial direction is stronger than that at axial direction for single aluminum wire-array implosion.
Azimuthal X-ray power distribution has been investigated in wire-array Z-pinch plasma implosions, using ST1432 scintillator, multi-mode quartz optical fiber and photomultiplier tube with the highest linear current. The load foils used in the experiments include single tungsten array and single aluminum array. And the driving current scales from 1.5 MA to 1.8 MA while the leading-edge pulse time varies from 20 ns to 90 ns. It is shown that X-ray power does not distribute evenly. X-ray radiation at axial direction is stronger than that at radial direction for tungsten wire-array implosion, while X-ray radiation at radial direction is stronger than that at axial direction for single aluminum wire-array implosion.
2009,
21.
Abstract:
To improve the gain and stability of output microwave，an X-band high power coupled cavity traveling wave tube(CCTWT) with one RF sever and two RF lumped attenuators is studied. As an example of dot frequency microwave input，the large signal beam-wave interaction at 7.2 GHz of this X-band CCTWT is simulated using 3D PIC code. The simulated results show that this tube can produce an output power of 2.0 kW，an electron efficiency of 14.7% and a gain of 23 dB with a cavity number of 40，a beam voltage of 17 kV and a beam current of 0.8 A.
To improve the gain and stability of output microwave，an X-band high power coupled cavity traveling wave tube(CCTWT) with one RF sever and two RF lumped attenuators is studied. As an example of dot frequency microwave input，the large signal beam-wave interaction at 7.2 GHz of this X-band CCTWT is simulated using 3D PIC code. The simulated results show that this tube can produce an output power of 2.0 kW，an electron efficiency of 14.7% and a gain of 23 dB with a cavity number of 40，a beam voltage of 17 kV and a beam current of 0.8 A.
2009,
21.
Abstract:
Involving a new idea of azimuthal partition in a symmetric magnetically insulated transmission line oscillator(MILO), an model of L-band bifrequency MILO(BFMILO) is put forward in this paper. By numerical analysis, dispersion curves of BFMILO are obtained. The resonators of BFMILO with closed boundary and open boundary are investigated, the parameters such as eigen-mode frequency, field distribution, Q-value, etc. are obtained. The investigation shows that, the structure of BFMILO can independently resonate in particular partitions, and each partition corresponds to a particular frequency. Thus the investigation proves the feasibility in the sight of high frequency characteristics that a BFMILO can generate high power microwave with two stable frequencies.
Involving a new idea of azimuthal partition in a symmetric magnetically insulated transmission line oscillator(MILO), an model of L-band bifrequency MILO(BFMILO) is put forward in this paper. By numerical analysis, dispersion curves of BFMILO are obtained. The resonators of BFMILO with closed boundary and open boundary are investigated, the parameters such as eigen-mode frequency, field distribution, Q-value, etc. are obtained. The investigation shows that, the structure of BFMILO can independently resonate in particular partitions, and each partition corresponds to a particular frequency. Thus the investigation proves the feasibility in the sight of high frequency characteristics that a BFMILO can generate high power microwave with two stable frequencies.
2009,
21.
Abstract:
According to the log-normal size distribution of the sand particles, the calculation model of microwave attenuation induced by the charged sand is got based on the forward scattering amplitude function under the Rayleigh approximation and the effective permittivity method. The attenuation is simulated and analyzed. The attenuation evidently increases with the charged sand particles to microwave signal, the more charge collection on surface of the charged sand particles, the stronger influence to the attenuation of microwave. And the attenuation evidently decreases with the visibility of sand particles increasing. Generally for sand with the same water content, the change of attenuation is small while the electromagnetic wave frequency below 35 GHz, the influence is obvious while the freque
According to the log-normal size distribution of the sand particles, the calculation model of microwave attenuation induced by the charged sand is got based on the forward scattering amplitude function under the Rayleigh approximation and the effective permittivity method. The attenuation is simulated and analyzed. The attenuation evidently increases with the charged sand particles to microwave signal, the more charge collection on surface of the charged sand particles, the stronger influence to the attenuation of microwave. And the attenuation evidently decreases with the visibility of sand particles increasing. Generally for sand with the same water content, the change of attenuation is small while the electromagnetic wave frequency below 35 GHz, the influence is obvious while the freque
2009,
21.
Abstract:
The effects of the misalignment between the inner-rod axis and the outer-wall axis in an open coaxial resonator are studied by the software CST microwave studio. Results show that the field amplitude and S parameter decrease with the oblique misalignment angle increase. But the effect is little, and the coaxial waveguide can work normally. While the oblique misalignment angle is 1°, the field profile of TEM mode at the coaxial waveguide’s port is much different from the profile with very small oblique misalignment angle, the device might not work normally.
The effects of the misalignment between the inner-rod axis and the outer-wall axis in an open coaxial resonator are studied by the software CST microwave studio. Results show that the field amplitude and S parameter decrease with the oblique misalignment angle increase. But the effect is little, and the coaxial waveguide can work normally. While the oblique misalignment angle is 1°, the field profile of TEM mode at the coaxial waveguide’s port is much different from the profile with very small oblique misalignment angle, the device might not work normally.
2009,
21.
Abstract:
Interrupt effects on telephone excited by high altitude electromagnetic pulse(HEMP) was investigated. Under the electromagnetic environment produced by a bounded-wave EMP simulator, probability distributions of phone call interrupt excited by 1976 HEMP and 1996 HEMP were presented and compared, and frequency spectra and electromagnetic norms were applied to analyse this effect’s mechanism. The results show that the interrupt threshold for 1996 HEMP is slightly lower than that for 1976 HEMP because the former contains more high frequency and both probability distributions can be fitted by normal distribution.
Interrupt effects on telephone excited by high altitude electromagnetic pulse(HEMP) was investigated. Under the electromagnetic environment produced by a bounded-wave EMP simulator, probability distributions of phone call interrupt excited by 1976 HEMP and 1996 HEMP were presented and compared, and frequency spectra and electromagnetic norms were applied to analyse this effect’s mechanism. The results show that the interrupt threshold for 1996 HEMP is slightly lower than that for 1976 HEMP because the former contains more high frequency and both probability distributions can be fitted by normal distribution.
2009,
21.
Abstract:
This paper describes a new antenna for realizing the directional radiation of helical array antenna fed from radial waveguide. The configuration parameters of the element and the layout of array antenna are optimized with the purpose of enhancing the aperture efficiency of the antenna. A circular array antenna composed of 6 elements with a frequency band of 1.5 GHz to 1.7 GHz is designed and simulated. The numerical simulation shows that at 1.57 GHz, the aperture efficiency reaches 99%, and the axial ratio at the normal direction is 1.15. In the range of 1.5 GHz to 1.7 GHz, the aperture efficiency is greater than 97%, the axial ratio is less than 1.35.
This paper describes a new antenna for realizing the directional radiation of helical array antenna fed from radial waveguide. The configuration parameters of the element and the layout of array antenna are optimized with the purpose of enhancing the aperture efficiency of the antenna. A circular array antenna composed of 6 elements with a frequency band of 1.5 GHz to 1.7 GHz is designed and simulated. The numerical simulation shows that at 1.57 GHz, the aperture efficiency reaches 99%, and the axial ratio at the normal direction is 1.15. In the range of 1.5 GHz to 1.7 GHz, the aperture efficiency is greater than 97%, the axial ratio is less than 1.35.
2009,
21.
Abstract:
A rigorous full wave analysis of nonradiative dielectric waveguide and H-waveguide with split ring resonator metamaterials is presented to investigate the different dispersion properties. Due to the bianisotropic effects of metamaterials, some abnormal higher-order longitudinal-section magnetic(LSM) and longitudinal-section electric(LSE) modes may come into existence when metamaterials have double negative parameters. However, for other LSM/LSE modes, leakage can be reduced by utilizing the bianisotropic effects. In addition, when the metamaterials have negative permittivity, leakage elimination can be achieved.
A rigorous full wave analysis of nonradiative dielectric waveguide and H-waveguide with split ring resonator metamaterials is presented to investigate the different dispersion properties. Due to the bianisotropic effects of metamaterials, some abnormal higher-order longitudinal-section magnetic(LSM) and longitudinal-section electric(LSE) modes may come into existence when metamaterials have double negative parameters. However, for other LSM/LSE modes, leakage can be reduced by utilizing the bianisotropic effects. In addition, when the metamaterials have negative permittivity, leakage elimination can be achieved.
2009,
21.
Abstract:
Mechanism of pulse-width effects on electronic components is described. The relationship of pulse-width and radiation response is presented. Five types of devices are tested under three different pulse-widths(about 20 ns,50 ns,150 ns) of different simulative radiation sources, the dose rate is about 106 to 109 Gy(Si)/s. The experiment results are analysed and discussed. The differences of radiation response under different pulse-widths are compared. It is shown that radiation effects are strongly influenced by pulse-width. Under the same radiation dose rate, longer γ pulse-width brings longer radiation storage time and stronger radiation response to devices. Discrete device is more obviously influenced by pulse-width than integrated circuit.
Mechanism of pulse-width effects on electronic components is described. The relationship of pulse-width and radiation response is presented. Five types of devices are tested under three different pulse-widths(about 20 ns,50 ns,150 ns) of different simulative radiation sources, the dose rate is about 106 to 109 Gy(Si)/s. The experiment results are analysed and discussed. The differences of radiation response under different pulse-widths are compared. It is shown that radiation effects are strongly influenced by pulse-width. Under the same radiation dose rate, longer γ pulse-width brings longer radiation storage time and stronger radiation response to devices. Discrete device is more obviously influenced by pulse-width than integrated circuit.
2009,
21.
Abstract:
The visual analysis method of data process was provided for neutron-induced single-event upset(SEU) in static random access memory(SRAM). The SEU effects of six CMOS SRAMs with different feature size (from 0.13 μm to 1.50 μm) were studied. The SEU experiments were performed using the neutron radiation environment at Xi’an pulsed reactor. And the dependence of low-energy neutron-induced SEU cross section on SRAM’s feature size was given. The results indicate that the decreased critical charge is the dominant factor for the increase of single event effect sensitivity of SRAM devices with decreased feature size. Small-sized SRAM devices are more sensitive than large-sized ones to single event effect induced by low-energy neutrons.
The visual analysis method of data process was provided for neutron-induced single-event upset(SEU) in static random access memory(SRAM). The SEU effects of six CMOS SRAMs with different feature size (from 0.13 μm to 1.50 μm) were studied. The SEU experiments were performed using the neutron radiation environment at Xi’an pulsed reactor. And the dependence of low-energy neutron-induced SEU cross section on SRAM’s feature size was given. The results indicate that the decreased critical charge is the dominant factor for the increase of single event effect sensitivity of SRAM devices with decreased feature size. Small-sized SRAM devices are more sensitive than large-sized ones to single event effect induced by low-energy neutrons.
2009,
21.
Abstract:
By using the multiconfiguration Dirac-Fock method, the radiative transition energies and transition probabilities of tin and xenon atoms in the ionization degree range from 7 to 13 are systematically calculated, and their convoluted spectra at wavelength near 13.5 nm are provided. The relativistic effect is found to increase the spectral energy by 2%, while the electronic correlation effect reduces the spectral energy by 5% in general. By comparing the emitted spectra from tin and xenon, the authors find that tin is a more efficient candidate element as the extreme ultraviolet(EUV) sources than xenon in view of the spectra.
By using the multiconfiguration Dirac-Fock method, the radiative transition energies and transition probabilities of tin and xenon atoms in the ionization degree range from 7 to 13 are systematically calculated, and their convoluted spectra at wavelength near 13.5 nm are provided. The relativistic effect is found to increase the spectral energy by 2%, while the electronic correlation effect reduces the spectral energy by 5% in general. By comparing the emitted spectra from tin and xenon, the authors find that tin is a more efficient candidate element as the extreme ultraviolet(EUV) sources than xenon in view of the spectra.
2009,
21.
Abstract:
The dynamic characteristics of micro-channel plate are simulated. The transit time and gain curves are obtained in the simulation. The simulation shows that the numbers of the electron collision on the channel wall of the microchannel plates(MCP) are related to the arriving time of the incident photoelectrons and the more frequently electrons collide with the channel, the longer transit time they need. The influence of the amplitude, width and shape of the driving voltage pulse on the exposure time and the gain of MCP are also studied when the incident electrons have a Gaussian distribution. It is concluded that the time of the peak value of the gain curve varies with different voltage pulse amplitude.
The dynamic characteristics of micro-channel plate are simulated. The transit time and gain curves are obtained in the simulation. The simulation shows that the numbers of the electron collision on the channel wall of the microchannel plates(MCP) are related to the arriving time of the incident photoelectrons and the more frequently electrons collide with the channel, the longer transit time they need. The influence of the amplitude, width and shape of the driving voltage pulse on the exposure time and the gain of MCP are also studied when the incident electrons have a Gaussian distribution. It is concluded that the time of the peak value of the gain curve varies with different voltage pulse amplitude.
2009,
21.
Abstract:
High gradient insulating technology is one of the key technologies in new type dielectric wall accelerator(DWA). High gradient insulator, namely micro-stacked insulator, was developed and preliminary experimental study was done. Based on the finite element and particle simulating method, surface electric field distribution and electron movement track of micro-stacked insulator were numerated, and then the optimized design proposal was put forward. Using high temperature laminated method, we developed micro-stacked insulator sampies which uses exhaustive fluorinated ethylene propylene(FEP) as dielectric layer and stainless steel as metal layer. Preliminary experiment of vacuum surface flashover in nanosecond pulse voltage was done and micro-stacked insulator exhibited favorable vacuum surfa
High gradient insulating technology is one of the key technologies in new type dielectric wall accelerator(DWA). High gradient insulator, namely micro-stacked insulator, was developed and preliminary experimental study was done. Based on the finite element and particle simulating method, surface electric field distribution and electron movement track of micro-stacked insulator were numerated, and then the optimized design proposal was put forward. Using high temperature laminated method, we developed micro-stacked insulator sampies which uses exhaustive fluorinated ethylene propylene(FEP) as dielectric layer and stainless steel as metal layer. Preliminary experiment of vacuum surface flashover in nanosecond pulse voltage was done and micro-stacked insulator exhibited favorable vacuum surfa
2009,
21.
Abstract:
Amplitude measurement uncertainty of high voltage pulse lies in the probe and oscillograph measurement. A D-dot probe has been designed to measure the voltage pulse at the input of a high-power triplate transmission line for the prototype of Z-pinch primary test stand. The uncertainty sources were analyzed. Type A evaluation of standard uncertainty was used to evaluate the random effect in calibration of the D-dot probe and the resistor divider. Type B evaluation of standard uncertainty was used to evaluate the random effect in measurement, the systematic effect of the calibration, and the uncertainty from the resolving ability of the oscillograph. The uncertainty of the attenuator and the oscillograph themselves are refer to the calibration document. The output waveform of the resistor di
Amplitude measurement uncertainty of high voltage pulse lies in the probe and oscillograph measurement. A D-dot probe has been designed to measure the voltage pulse at the input of a high-power triplate transmission line for the prototype of Z-pinch primary test stand. The uncertainty sources were analyzed. Type A evaluation of standard uncertainty was used to evaluate the random effect in calibration of the D-dot probe and the resistor divider. Type B evaluation of standard uncertainty was used to evaluate the random effect in measurement, the systematic effect of the calibration, and the uncertainty from the resolving ability of the oscillograph. The uncertainty of the attenuator and the oscillograph themselves are refer to the calibration document. The output waveform of the resistor di
2009,
21.
Abstract:
A kind of self-integrated Rogowski coil is designed. Through circuit theory and simulation analyses, the impacts on the measured signal, which are caused by the sampling resistor’s residual inductance and the coil’s ground capacitance, have been studied. By shunt-wound method, we have made and calibrated a low-inductance sampling resistor. In the calibration and measure experiments, oscillation and deformation of the measured signal were eliminated resistor. And the theoretical analyses are supported by the experiments. The Rogowski coil’s responding time to square pulse signal is 11 ns, and its sensitivity is 4.25 mV/A. For its good stability, we use the coil to measure the current of the diode of the long-pulsed intense electron beam accelerator and get the current waveform with flat-
A kind of self-integrated Rogowski coil is designed. Through circuit theory and simulation analyses, the impacts on the measured signal, which are caused by the sampling resistor’s residual inductance and the coil’s ground capacitance, have been studied. By shunt-wound method, we have made and calibrated a low-inductance sampling resistor. In the calibration and measure experiments, oscillation and deformation of the measured signal were eliminated resistor. And the theoretical analyses are supported by the experiments. The Rogowski coil’s responding time to square pulse signal is 11 ns, and its sensitivity is 4.25 mV/A. For its good stability, we use the coil to measure the current of the diode of the long-pulsed intense electron beam accelerator and get the current waveform with flat-
2009,
21.
Abstract:
This paper introduces how to choose magnetic cores in the applications of narrow width pulses and the design of a onestage linear transformer driver(LTD) module powered by two parallel circuits. The LTD response characteristics of different width of low voltage pulses are measured and then high voltage experiments are carried out based on the pulse forming net with an impedance of about 5 Ω which can produce square wave pulses with duration of about 3 μs. The voltage waveforms of the secondary winding of the LTD are in good coincidence with the ouput voltage waveforms of PFN. A simplified circuit model of LTD is investigated and some important results are obtained with the method of Laplace transform. The reasons why the output voltage of LTD is lower than half of the charging voltage
This paper introduces how to choose magnetic cores in the applications of narrow width pulses and the design of a onestage linear transformer driver(LTD) module powered by two parallel circuits. The LTD response characteristics of different width of low voltage pulses are measured and then high voltage experiments are carried out based on the pulse forming net with an impedance of about 5 Ω which can produce square wave pulses with duration of about 3 μs. The voltage waveforms of the secondary winding of the LTD are in good coincidence with the ouput voltage waveforms of PFN. A simplified circuit model of LTD is investigated and some important results are obtained with the method of Laplace transform. The reasons why the output voltage of LTD is lower than half of the charging voltage
2009,
21.
Abstract:
According to the results of the code MFCG8-7 based on the circuit model, an EMG-125 type generator has been designed and tested. The EMG-125 generator is 900 mm in length, 125 mm in diameter, and its charging explosive weighs 2.7 kg. A series of experiments show that, there would be serious breakdowns inside the generator if the input current is beyond the limit of 8 kA (the limit of the input energy is about 2 kJ). In the case of input current 8 kA, the peak current 3 MA was measured on the inductive load 25 nH, which is 0.3 MA less than the calculated result without magnetic flux losses. The maximal energy on the inductive load is 100 kJ with the peak gain of 50. The calculated results agree with the experimental results when the calibrated coefficient of magnetic flux losses is set as 0
According to the results of the code MFCG8-7 based on the circuit model, an EMG-125 type generator has been designed and tested. The EMG-125 generator is 900 mm in length, 125 mm in diameter, and its charging explosive weighs 2.7 kg. A series of experiments show that, there would be serious breakdowns inside the generator if the input current is beyond the limit of 8 kA (the limit of the input energy is about 2 kJ). In the case of input current 8 kA, the peak current 3 MA was measured on the inductive load 25 nH, which is 0.3 MA less than the calculated result without magnetic flux losses. The maximal energy on the inductive load is 100 kJ with the peak gain of 50. The calculated results agree with the experimental results when the calibrated coefficient of magnetic flux losses is set as 0
2009,
21.
Abstract:
This paper presents the research carried out with the semiconductor opening switch(SOS). Loaded with high frequency pumping current, the switch could work on high frequency (1 MHz). A high frequency nanosecond-pulsed generator with a pulse power up to 9.3 MW, output voltage of 22.0~35.7 kV, pulse duration of about 10 ns, and repetition rates of 10 kHz is developed. Ultrafast IGBT is used in primary charged unit to provide low voltage pulse for magnetic compression unit. The magnetic switch and saturable transformer are used to compress primary pulse and pump SOS. The reverse pumping current switching-off is performed by SOS in about 4.3 ns, which results in the formation of an output voltage pulse across output load.
This paper presents the research carried out with the semiconductor opening switch(SOS). Loaded with high frequency pumping current, the switch could work on high frequency (1 MHz). A high frequency nanosecond-pulsed generator with a pulse power up to 9.3 MW, output voltage of 22.0~35.7 kV, pulse duration of about 10 ns, and repetition rates of 10 kHz is developed. Ultrafast IGBT is used in primary charged unit to provide low voltage pulse for magnetic compression unit. The magnetic switch and saturable transformer are used to compress primary pulse and pump SOS. The reverse pumping current switching-off is performed by SOS in about 4.3 ns, which results in the formation of an output voltage pulse across output load.
2009,
21.
Abstract:
Theoretical analysis and experimental study have been carried out on the thermal conduction during the discharge process in pulsed magnets. The simulation results show that, for the short pulse magnet, the results obtained from models with and without thermal conduction agree well with each other. The results from theoretical analysis and experiments are also in good agreement. For the long pulse magnet, the temperature difference between models with and without thermal conduction becomes non-negligible. The theoretical analysis shows that, for both short and long pulse magnets, the thermal conduction influences only the temperature distribution, not the waveform of the pulse magnetic field.
Theoretical analysis and experimental study have been carried out on the thermal conduction during the discharge process in pulsed magnets. The simulation results show that, for the short pulse magnet, the results obtained from models with and without thermal conduction agree well with each other. The results from theoretical analysis and experiments are also in good agreement. For the long pulse magnet, the temperature difference between models with and without thermal conduction becomes non-negligible. The theoretical analysis shows that, for both short and long pulse magnets, the thermal conduction influences only the temperature distribution, not the waveform of the pulse magnetic field.
2009,
21.
Abstract:
This paper discusses the shimming and the optimization algorithm of the integrated multipoles and the first and second field integrals of the EPU100 at Shanghai synchrotron radiation facility. To shim the integrated multipoles, the “Magic Fingers” technique is used, which is a proper arrangement of small magnet cylinders to reduce variation of the field integral errors; and the 8 trimming coils installed at the two ends of the undulator are used to shim the first and second field integrals. After shimming all the operating gaps or polarized modes of the EPU100, the quadrupole component is less than 9×10-3 T, the sextupole component is less than 1.6 T/m, and the octupole component is less than 30 T/m2, the multipole components are all well within the specifications.
This paper discusses the shimming and the optimization algorithm of the integrated multipoles and the first and second field integrals of the EPU100 at Shanghai synchrotron radiation facility. To shim the integrated multipoles, the “Magic Fingers” technique is used, which is a proper arrangement of small magnet cylinders to reduce variation of the field integral errors; and the 8 trimming coils installed at the two ends of the undulator are used to shim the first and second field integrals. After shimming all the operating gaps or polarized modes of the EPU100, the quadrupole component is less than 9×10-3 T, the sextupole component is less than 1.6 T/m, and the octupole component is less than 30 T/m2, the multipole components are all well within the specifications.
2009,
21.
Abstract:
In order to carry out studies on THz source based on FEL technology and obtain high quality electron beam(heavy current, small energy spread and low emittance), a design scheme of an RF gun with two independent microwave power feed-in ports is proposed. Two microwave feed-in ports will be used to drive the microwave gun. One is used to drive the first cavity and draw electrons from the cathode surface. The other is used to excite the following cavity. There is no electromagnetic coupling between the first cavity and the following cavities. Numerical simulation results show that the electron back bombardment of the thermionic-cathode microwave gun can greatly decrease, the back electron bombardment power within one RF period is no more than 8 kW, and the average back electron bombardment
In order to carry out studies on THz source based on FEL technology and obtain high quality electron beam(heavy current, small energy spread and low emittance), a design scheme of an RF gun with two independent microwave power feed-in ports is proposed. Two microwave feed-in ports will be used to drive the microwave gun. One is used to drive the first cavity and draw electrons from the cathode surface. The other is used to excite the following cavity. There is no electromagnetic coupling between the first cavity and the following cavities. Numerical simulation results show that the electron back bombardment of the thermionic-cathode microwave gun can greatly decrease, the back electron bombardment power within one RF period is no more than 8 kW, and the average back electron bombardment
2009,
21.
Abstract:
Based on the principle that the synchrotron light has the same time structure with the beam signal, bunch length can be calculated by measuring the full width half height of the synchrotron light pulse. The variation of bunch length with beam current and RF loltage in single bunch mode was measured. And the result shows that the bunch length is in reverse proportion to the RF voltage to the power of 0.3 and it is smaller than the theoretical result. The growth rate of bunch length with the beam current is 2.0 ps/mA. The energy spread was measured by measuring the longitudinal quantum lifetime, which indicates that the bunch lengthening is the result of energy spread and potential well distortion．
Based on the principle that the synchrotron light has the same time structure with the beam signal, bunch length can be calculated by measuring the full width half height of the synchrotron light pulse. The variation of bunch length with beam current and RF loltage in single bunch mode was measured. And the result shows that the bunch length is in reverse proportion to the RF voltage to the power of 0.3 and it is smaller than the theoretical result. The growth rate of bunch length with the beam current is 2.0 ps/mA. The energy spread was measured by measuring the longitudinal quantum lifetime, which indicates that the bunch lengthening is the result of energy spread and potential well distortion．
