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RSS2007 Vol. 19, No. 02
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2007,
19.
Abstract:
The method to estimate the detectable stellar magnitude limit in daytime sky background is introduced. Based on the results of the contrast of star to sky background in daytime, the detectable stellar magnitude limits are computed and analyzed as functions of observing heights, solar zeniths angle, wavebands and stellar spectral types for 3°3° field of view. The results show that the detectable stellar magnitude limits linearly increase with observing height and solar zenith angle. A higher detectable stellar magnitude limit is obtained by using longer wavelength bands for stars of K and M types. For the case of 25 km observing altitude, the field of view of 3°3°, the maximum detectable stellar magnitude limit is 6.3 when the sun is out of 20° line of sight.
The method to estimate the detectable stellar magnitude limit in daytime sky background is introduced. Based on the results of the contrast of star to sky background in daytime, the detectable stellar magnitude limits are computed and analyzed as functions of observing heights, solar zeniths angle, wavebands and stellar spectral types for 3°3° field of view. The results show that the detectable stellar magnitude limits linearly increase with observing height and solar zenith angle. A higher detectable stellar magnitude limit is obtained by using longer wavelength bands for stars of K and M types. For the case of 25 km observing altitude, the field of view of 3°3°, the maximum detectable stellar magnitude limit is 6.3 when the sun is out of 20° line of sight.
2007,
19.
Abstract:
Supercontinuum generation incorporates many nonlinear effects. In our experiment, two supercontinuum pulses generated independently by ultrashort pulses form stable spatial interference fringes and a frequency comb appears with collinear time-delay pump pulses. The supercontinuum keeps phase-lock relationships of the pump beams. Small intensity variations in the pump and small inhomogeneities in the material do not lead to dramatic phase fluctuations in the generated supercontinuum. It is important for supercontinuum simulation and studying of supercontinuum frequency combs in bulk material.
Supercontinuum generation incorporates many nonlinear effects. In our experiment, two supercontinuum pulses generated independently by ultrashort pulses form stable spatial interference fringes and a frequency comb appears with collinear time-delay pump pulses. The supercontinuum keeps phase-lock relationships of the pump beams. Small intensity variations in the pump and small inhomogeneities in the material do not lead to dramatic phase fluctuations in the generated supercontinuum. It is important for supercontinuum simulation and studying of supercontinuum frequency combs in bulk material.
2007,
19.
Abstract:
It is important to evaluate sky radiance for a ground-to-air measurement system. Based on energy conservation law and the assumption that the underlying surface is a Lambert’s surface, a model was developed to calculate the additional sky radiance due to the ground reflectance. According to the ray trace principle, multiple reflectance between the earth’s albedo surface and the atmosphere was also taken into account. The hybrid modified delta-Eddington approximation was used to calculate the transmission, reflection and average reflection of the atmosphere from the ground to the top of the atmosphere. The additional sky radiance was calculated under surface albedos of 0.15, 0.25 and 0.35, and compared with the measured data. The results show that there is a limb-brightening effect for sk
It is important to evaluate sky radiance for a ground-to-air measurement system. Based on energy conservation law and the assumption that the underlying surface is a Lambert’s surface, a model was developed to calculate the additional sky radiance due to the ground reflectance. According to the ray trace principle, multiple reflectance between the earth’s albedo surface and the atmosphere was also taken into account. The hybrid modified delta-Eddington approximation was used to calculate the transmission, reflection and average reflection of the atmosphere from the ground to the top of the atmosphere. The additional sky radiance was calculated under surface albedos of 0.15, 0.25 and 0.35, and compared with the measured data. The results show that there is a limb-brightening effect for sk
2007,
19.
Abstract:
A 24 h experimental measurement for angle-of-arrival fluctuations on a 3.2 km line-of-sight link in Harbin was carried out over a three-month period in 2006. In the experiment, the measurement over a 10 s period at a high sampling rate of 1 kHz was carried out per min, and the angle-of-arrival experimental data which contained the frequency range of 0.2~500 Hz were achieved. Angle-of-arrival fluctuations and its time-averaging effects were studied experimentally and theoretically. The experimental results provide information on the characteristics of angle-of-arrival fluctuations, which can provide important information for the design of free-space optical links. The results show that the intensity of the angle-of-arrival fluctuation in the haze weather and low visibility is smaller than t
A 24 h experimental measurement for angle-of-arrival fluctuations on a 3.2 km line-of-sight link in Harbin was carried out over a three-month period in 2006. In the experiment, the measurement over a 10 s period at a high sampling rate of 1 kHz was carried out per min, and the angle-of-arrival experimental data which contained the frequency range of 0.2~500 Hz were achieved. Angle-of-arrival fluctuations and its time-averaging effects were studied experimentally and theoretically. The experimental results provide information on the characteristics of angle-of-arrival fluctuations, which can provide important information for the design of free-space optical links. The results show that the intensity of the angle-of-arrival fluctuation in the haze weather and low visibility is smaller than t
2007,
19.
Abstract:
By using the second-order moment method of the power density and a new model of flat-topped beams, the waist width，far-field divergence angle and beam quality factor of nonparaxial truncated flat-topped beams are derived analytically. It is shown that the beam quality factor of nonparaxial truncated flat-topped beams depends on the truncation parameter, the beam order and the initial waist-width to wavelength ratio. The far-field divergence angle approaches an asymptotic value of 63.435° when the truncation parameter approaches to 0. For the special case of 1 order beam and the truncation parameter approaching to +∞, the results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated flat-topped beams, respectively. It is also shown that the second-order mome
By using the second-order moment method of the power density and a new model of flat-topped beams, the waist width，far-field divergence angle and beam quality factor of nonparaxial truncated flat-topped beams are derived analytically. It is shown that the beam quality factor of nonparaxial truncated flat-topped beams depends on the truncation parameter, the beam order and the initial waist-width to wavelength ratio. The far-field divergence angle approaches an asymptotic value of 63.435° when the truncation parameter approaches to 0. For the special case of 1 order beam and the truncation parameter approaching to +∞, the results reduce to those of nonparaxial truncated Gaussian beams and nonparaxial untruncated flat-topped beams, respectively. It is also shown that the second-order mome
2007,
19.
Abstract:
The propagation of a focused Gaussian beam through turbulent atmosphere is simulated by using non-adaptive coordinate transformation. The first-order weak-fluctuation Rytov theory predicts that the on-axis scintillation index would become significantly smaller as the initial beam width increases. But the simulation results show that there is no great reduction of on-axis scintillation index. This discrepancy is due to the fact that Rytov theory does not correctly account for the effects of beam wander caused by large scale turbulence. Simulation results are in good agreement with beam wander theory results and experimental data. It can be concluded that Rytov theory could not correctly calculate the scintillation index of a focused beam and the effects of beam wander should be taken into a
The propagation of a focused Gaussian beam through turbulent atmosphere is simulated by using non-adaptive coordinate transformation. The first-order weak-fluctuation Rytov theory predicts that the on-axis scintillation index would become significantly smaller as the initial beam width increases. But the simulation results show that there is no great reduction of on-axis scintillation index. This discrepancy is due to the fact that Rytov theory does not correctly account for the effects of beam wander caused by large scale turbulence. Simulation results are in good agreement with beam wander theory results and experimental data. It can be concluded that Rytov theory could not correctly calculate the scintillation index of a focused beam and the effects of beam wander should be taken into a
2007,
19.
Abstract:
The pump LD intensity distribution model under the Gaussian intensity approximate condition was revised, and the numerical model of the temperature field was established in the crystal cylinder of diode side-pumping solid state laser. The temperature field and warming process of the transient and steady state in the laser rod by symmetrical trigonal side-pumping were simulated using the finite element analysis method. The temperature field distributions in the laser crystal of the Gaussian intensity and uniform intensity hypothesis were presented and compared, and the thermal lens focus of the crystal cylinder was measured experimentally. It is concluded that the LDA pumping structure and the non-uniformity of the cooling field make the experiment results divergent from those of the simula
The pump LD intensity distribution model under the Gaussian intensity approximate condition was revised, and the numerical model of the temperature field was established in the crystal cylinder of diode side-pumping solid state laser. The temperature field and warming process of the transient and steady state in the laser rod by symmetrical trigonal side-pumping were simulated using the finite element analysis method. The temperature field distributions in the laser crystal of the Gaussian intensity and uniform intensity hypothesis were presented and compared, and the thermal lens focus of the crystal cylinder was measured experimentally. It is concluded that the LDA pumping structure and the non-uniformity of the cooling field make the experiment results divergent from those of the simula
2007,
19.
Abstract:
A direct detection Doppler wind lidar with the dual Fabry-Perot technique has been built and the system is described. The dual etalon with high-spectral resolution is used to discriminate the Doppler shift by the aerosol backscattering. Analysis shows that the etalon transmittance is affected by the beam divergence. The stability of the dual etalon is also analyzed and the result shows the system is steady in 100 min. The transmittance curve of the dual etalon is measured, which indicates that the error in the velocity dynamic range is less than 0.6 m/s for heights up to 5 km and the error increases with the large radial velocity and decreases with pulse number increasing.
A direct detection Doppler wind lidar with the dual Fabry-Perot technique has been built and the system is described. The dual etalon with high-spectral resolution is used to discriminate the Doppler shift by the aerosol backscattering. Analysis shows that the etalon transmittance is affected by the beam divergence. The stability of the dual etalon is also analyzed and the result shows the system is steady in 100 min. The transmittance curve of the dual etalon is measured, which indicates that the error in the velocity dynamic range is less than 0.6 m/s for heights up to 5 km and the error increases with the large radial velocity and decreases with pulse number increasing.
2007,
19.
Abstract:
A new method is proposed for the measurement of refractive index of aerosol by using a visibility meter(VM), an optical particle counter(OPC) and a micro pulse lidar(MPL). The extinction coefficient and ratio of extinction-to-backscatter are measured with a VM and micro pulse lidar, the number density distribution of aerosol particles is measured by an OPC with nominated radii. According to the Mie scattering theory, different distributions can be obtained with different refractive index for the same result measured by OPC. The variations of both extinction coefficient and ratio of extinction-to-backscatter can be calculated with different refractive index. The solution of refractive index can be decided according to the value of extinction coefficient and ratio of extinction-to-backscatte
A new method is proposed for the measurement of refractive index of aerosol by using a visibility meter(VM), an optical particle counter(OPC) and a micro pulse lidar(MPL). The extinction coefficient and ratio of extinction-to-backscatter are measured with a VM and micro pulse lidar, the number density distribution of aerosol particles is measured by an OPC with nominated radii. According to the Mie scattering theory, different distributions can be obtained with different refractive index for the same result measured by OPC. The variations of both extinction coefficient and ratio of extinction-to-backscatter can be calculated with different refractive index. The solution of refractive index can be decided according to the value of extinction coefficient and ratio of extinction-to-backscatte
2007,
19.
Abstract:
The two-phase model(TPM) is proved to be available in calculation of jet singlet oxygen generator(JSOG). The result of numerical simulation illustrates that the type of the generator kinetics is dependant on the relative concentration between chlorine and BHP, when the other parameters are fixed. An improved method determining the type of the generator kinetics by using the curve of chlorine absorption rate is presented. The TPM, including the thermal effect, could compute temperature and the fraction of water vapor. The results agrees with the experiment well.
The two-phase model(TPM) is proved to be available in calculation of jet singlet oxygen generator(JSOG). The result of numerical simulation illustrates that the type of the generator kinetics is dependant on the relative concentration between chlorine and BHP, when the other parameters are fixed. An improved method determining the type of the generator kinetics by using the curve of chlorine absorption rate is presented. The TPM, including the thermal effect, could compute temperature and the fraction of water vapor. The results agrees with the experiment well.
2007,
19.
Abstract:
The modal analysis method studying the elastic support rotating mirror for ultra-high speed photography was presented. With the finite element technology，the first and second modes of the three-faced aluminum alloy mirror were simulated under the stiff and elastic bearings condition. The simulation results show that the only two resonance points are in the speed ranges of 2.5×105 to 2.6×105 r/min and 2.6×105 to 2.7×105 r/min respectively, both resonances are first order flexure vibrations. The vibration of the first order modal occurs in vertical plane and that of the second occurs in level plane. The simulation results under the elastic supporting hypothesis are more close to that of the experimental results.
The modal analysis method studying the elastic support rotating mirror for ultra-high speed photography was presented. With the finite element technology，the first and second modes of the three-faced aluminum alloy mirror were simulated under the stiff and elastic bearings condition. The simulation results show that the only two resonance points are in the speed ranges of 2.5×105 to 2.6×105 r/min and 2.6×105 to 2.7×105 r/min respectively, both resonances are first order flexure vibrations. The vibration of the first order modal occurs in vertical plane and that of the second occurs in level plane. The simulation results under the elastic supporting hypothesis are more close to that of the experimental results.
2007,
19.
Abstract:
Using polar coordinates to optimize the fractal model, a novel segmentation algorithm is proposed to deal with extended target under complex environment. First, analyses is introduced for characteristics of morphology operator with variable algebra structures in polar coordinates, corresponding the dilating operations progress to construct a series of covering surfaces. Secondly the fractal feature, named Scale Error, is extracted by the least square method. Then eroding filters eliminate clutter texture. After the course of edge linking, the region with the biggest area is preserved as a target based on transcendental knowledge. Abundance experiments under complex environment test its validity and the contour of extended target is kept intact and perfect.
Using polar coordinates to optimize the fractal model, a novel segmentation algorithm is proposed to deal with extended target under complex environment. First, analyses is introduced for characteristics of morphology operator with variable algebra structures in polar coordinates, corresponding the dilating operations progress to construct a series of covering surfaces. Secondly the fractal feature, named Scale Error, is extracted by the least square method. Then eroding filters eliminate clutter texture. After the course of edge linking, the region with the biggest area is preserved as a target based on transcendental knowledge. Abundance experiments under complex environment test its validity and the contour of extended target is kept intact and perfect.
2007,
19.
Abstract:
The DNB (diagnostic neutral beam) device is a physical diagnostic system. The timing control subsystem plays a critical role in running DNB device. In order to produce diagnostic neutral beam accordantly with desire, timing control must provide a series of pulses accurately and orderly. The control requestments of the DNB system are studied. Based on this, the timing control unit is designed, including structure of PC in combination with PIC single chip microcomputer and software application. The experiment shows that the timing control unit is steady and reliable.
The DNB (diagnostic neutral beam) device is a physical diagnostic system. The timing control subsystem plays a critical role in running DNB device. In order to produce diagnostic neutral beam accordantly with desire, timing control must provide a series of pulses accurately and orderly. The control requestments of the DNB system are studied. Based on this, the timing control unit is designed, including structure of PC in combination with PIC single chip microcomputer and software application. The experiment shows that the timing control unit is steady and reliable.
2007,
19.
Abstract:
In order to study the mechanism of laser interacting with materials in laser propulsion technique, the parameters related to plasma state and mechanics are needed. The plasma spectra and temperature are measured by laser-induced plasma spectroscopy, the mechanical parameters are obtained by impulse pendulum, as a passive Q-switch solid laser is ablating hard aluminum. The experimental results demonstrate that the plasma temperature on material surface declines with time in quadratic curve mode under laser power density of 0.534×108 W/cm2. Changing the laser power density around the material plasma ignition threshold, it is found that the plasma temperature and the momentum coupling coefficients increase with the increase of the power density, they reach the maximum as the power density re
In order to study the mechanism of laser interacting with materials in laser propulsion technique, the parameters related to plasma state and mechanics are needed. The plasma spectra and temperature are measured by laser-induced plasma spectroscopy, the mechanical parameters are obtained by impulse pendulum, as a passive Q-switch solid laser is ablating hard aluminum. The experimental results demonstrate that the plasma temperature on material surface declines with time in quadratic curve mode under laser power density of 0.534×108 W/cm2. Changing the laser power density around the material plasma ignition threshold, it is found that the plasma temperature and the momentum coupling coefficients increase with the increase of the power density, they reach the maximum as the power density re
2007,
19.
Abstract:
In order to further understand the Z-pinch physical process and to optimize the experimental design, it is necessary to develop time-space-resolved diagnostic technique and corresponding equipments for investigation of imploding plasma and radiation distribution. Based on these diagnostic technique and equipments, experimental studies of plasma imploding process and spatial distribution can be conducted, which provide experimental verifications of numerical simulations. A brief summary of recent researches on the time-space-resolved diagnostic technique is given, including spatially integrated time-dependent X-ray power measurement, temporally integrated X-ray pinhole photography, X-ray framing photography, time-resolved 1D imaging, and plasma shadowgraph using UV laser probing. Typical ex
In order to further understand the Z-pinch physical process and to optimize the experimental design, it is necessary to develop time-space-resolved diagnostic technique and corresponding equipments for investigation of imploding plasma and radiation distribution. Based on these diagnostic technique and equipments, experimental studies of plasma imploding process and spatial distribution can be conducted, which provide experimental verifications of numerical simulations. A brief summary of recent researches on the time-space-resolved diagnostic technique is given, including spatially integrated time-dependent X-ray power measurement, temporally integrated X-ray pinhole photography, X-ray framing photography, time-resolved 1D imaging, and plasma shadowgraph using UV laser probing. Typical ex
2007,
19.
Abstract:
Laser driven shock wave stability of propagation in impedance match target was studied using one dimension characteristic line method. In addition, one dimension three temperature laser-target coupling JB program was used to simulate it. It was compared with simplified equation of state. The results of the two methods agree well. The calculation results show that shock wave stability of propagation in Au depends closely on the thickness of the Al base.
Laser driven shock wave stability of propagation in impedance match target was studied using one dimension characteristic line method. In addition, one dimension three temperature laser-target coupling JB program was used to simulate it. It was compared with simplified equation of state. The results of the two methods agree well. The calculation results show that shock wave stability of propagation in Au depends closely on the thickness of the Al base.
2007,
19.
Abstract:
For exploring the transport characteristic of hot electron bunches, the integrated image pattern of optical transition radiation were measured at the normal direction of the rear side of targets employing the optical CCD camera. The experiment was carried out on the 100 TW laser. The transition radiation facula on the rear side of a 20 μm thick target Ta was a smooth round structure with the center brighter than the periphery, indicating incoherent transition radiation and coherent transition radiation, which is close to the results of the theoretical simulations. For a 100 μm thick target Ta, the facula was a star-structure and became smaller, which resembles a star-structure of the energetic proton emission. For a 10 μm Ta + 10 μm Cu+5 μm Ta composite target, the facula was a ring s
For exploring the transport characteristic of hot electron bunches, the integrated image pattern of optical transition radiation were measured at the normal direction of the rear side of targets employing the optical CCD camera. The experiment was carried out on the 100 TW laser. The transition radiation facula on the rear side of a 20 μm thick target Ta was a smooth round structure with the center brighter than the periphery, indicating incoherent transition radiation and coherent transition radiation, which is close to the results of the theoretical simulations. For a 100 μm thick target Ta, the facula was a star-structure and became smaller, which resembles a star-structure of the energetic proton emission. For a 10 μm Ta + 10 μm Cu+5 μm Ta composite target, the facula was a ring s
2007,
19.
Abstract:
The substrate effects on the measurement of weak absorption of optical thin films at low frequency are analysed in theory. The absorptions of different thin films, including single-layer HfO2 and ZnO thin films with different thickness, on two substrates (BK7 and silica), as well as absorptions of blank substrates have been measured by surface thermal lensing technique. As a calibrated sample, the absorptions of singal-layer Ti3O5 thin films were measured by Lambda—900 spectrometer. The experimental results show that the substrate of standard film is the same as the substrate of sample in calibration for low measurement is necessary. After considering the influence of film thickness，the correction would be possible.
The substrate effects on the measurement of weak absorption of optical thin films at low frequency are analysed in theory. The absorptions of different thin films, including single-layer HfO2 and ZnO thin films with different thickness, on two substrates (BK7 and silica), as well as absorptions of blank substrates have been measured by surface thermal lensing technique. As a calibrated sample, the absorptions of singal-layer Ti3O5 thin films were measured by Lambda—900 spectrometer. The experimental results show that the substrate of standard film is the same as the substrate of sample in calibration for low measurement is necessary. After considering the influence of film thickness，the correction would be possible.
2007,
19.
Abstract:
Polyurethane-modified TDE-85/MeTHPA epoxy resin was prepared with polyurethane prepolymer (PUP). The effects of the molecular weight of polypropylene glycol (PPG), the content of PUP, and other factors on the resin′s mechanical properties were discussed. The results indicate that the tensile strength and impact strength of the material increase to maximum successively, then decrease with the increasing addition of PUP. The mechanical properties of materials obtained are distinctively different because of different molecular weight of PPG. When the PPG′s molecular weight is 1 000 and the mass fraction of PUP is 15%, the integrity mechanical property of the modified material is improved obviously. Its tensile strength is 69.39 MPa and its impact strength is 23.56 kJ/m2.
Polyurethane-modified TDE-85/MeTHPA epoxy resin was prepared with polyurethane prepolymer (PUP). The effects of the molecular weight of polypropylene glycol (PPG), the content of PUP, and other factors on the resin′s mechanical properties were discussed. The results indicate that the tensile strength and impact strength of the material increase to maximum successively, then decrease with the increasing addition of PUP. The mechanical properties of materials obtained are distinctively different because of different molecular weight of PPG. When the PPG′s molecular weight is 1 000 and the mass fraction of PUP is 15%, the integrity mechanical property of the modified material is improved obviously. Its tensile strength is 69.39 MPa and its impact strength is 23.56 kJ/m2.
2007,
19.
Abstract:
The radiative heat wave in matter is an important issue concerned by inertial confinement fusion(ICF) and astrophysics. However, accurate analytic diffusion wave solutions are difficult to obtain due to the strong nonlinearity of the radiation diffusion equation. With a perturbation technique, the heat front position and temperature of surface for arbitrary net driven flux time history is present. The result shows good agreement with the numerical simulation.
The radiative heat wave in matter is an important issue concerned by inertial confinement fusion(ICF) and astrophysics. However, accurate analytic diffusion wave solutions are difficult to obtain due to the strong nonlinearity of the radiation diffusion equation. With a perturbation technique, the heat front position and temperature of surface for arbitrary net driven flux time history is present. The result shows good agreement with the numerical simulation.
2007,
19.
Abstract:
CCD; 探测效率; X射线测量; 激光等离子体
CCD; 探测效率; X射线测量; 激光等离子体
2007,
19.
Abstract:
Base on the Foulds′ theory about the propagation of an electromagnetic wave through a helical waveguide, the effect of the higher-order modes in the groove is taken into account. The dispersion diagram obtained from calculation agrees very well with the results of reference when the groove width is smaller and different from the instance of bigger groove width. Moreover, some characteristics of helical groove gyrotwt are discussed. The results shows that when the structure parameters (except groove width) are fixed, there is a best value of groove width to pitch, it can obtain relatively weak dispersion characteristics and big amplitude of transverse electric field. The helical groove structure can be used in the gyrotwt.
Base on the Foulds′ theory about the propagation of an electromagnetic wave through a helical waveguide, the effect of the higher-order modes in the groove is taken into account. The dispersion diagram obtained from calculation agrees very well with the results of reference when the groove width is smaller and different from the instance of bigger groove width. Moreover, some characteristics of helical groove gyrotwt are discussed. The results shows that when the structure parameters (except groove width) are fixed, there is a best value of groove width to pitch, it can obtain relatively weak dispersion characteristics and big amplitude of transverse electric field. The helical groove structure can be used in the gyrotwt.
2007,
19.
Abstract:
This paper proposes new a laser-controlled superconducting microwave variable attenuator which can be used in high- temperature superconducting (HTS) subsystem of satellites. The design process and experimental results are analyzed. Low microwave surface resistance and excellent laser response characteristics of HTS film are contributed to the favorable properties of this attenuator. A transition metal and a transparent material are adopted in the structure of HTS attenuator to ensure the grounded capability and the laser position on substrate. The results show that this attenuator, which is 12 mm×8 mm×0.5 mm and works at low temperature, can be used alone or integrated into HTS system to decrease system volume and weight. Insertion loss of this attenuator is about 0.2 dB, whose magnitud
This paper proposes new a laser-controlled superconducting microwave variable attenuator which can be used in high- temperature superconducting (HTS) subsystem of satellites. The design process and experimental results are analyzed. Low microwave surface resistance and excellent laser response characteristics of HTS film are contributed to the favorable properties of this attenuator. A transition metal and a transparent material are adopted in the structure of HTS attenuator to ensure the grounded capability and the laser position on substrate. The results show that this attenuator, which is 12 mm×8 mm×0.5 mm and works at low temperature, can be used alone or integrated into HTS system to decrease system volume and weight. Insertion loss of this attenuator is about 0.2 dB, whose magnitud
2007,
19.
Abstract:
Using a 2.5 dimensional fully electromagnetic particle-in-cell (PIC) code, a new type of MILO was designed. A circle is placed at the launch point to improve the interaction between the electron beam and the fields supported by the slow wave structure, thus to control the beam current density at the launch point, and to minimize the loss of the electron beam energy. The inner radii of the extractor vanes are slightly larger than those of other SWS vanes, which increases the axial group velocity and enhances the microwave output power and efficiency. Implementation of two RF choke vanes stops the leakage of microwave pulse power toward the diode, and makes the device more compact than the conventional MILO. High power microwave is generated from the device with an average output power of 2
Using a 2.5 dimensional fully electromagnetic particle-in-cell (PIC) code, a new type of MILO was designed. A circle is placed at the launch point to improve the interaction between the electron beam and the fields supported by the slow wave structure, thus to control the beam current density at the launch point, and to minimize the loss of the electron beam energy. The inner radii of the extractor vanes are slightly larger than those of other SWS vanes, which increases the axial group velocity and enhances the microwave output power and efficiency. Implementation of two RF choke vanes stops the leakage of microwave pulse power toward the diode, and makes the device more compact than the conventional MILO. High power microwave is generated from the device with an average output power of 2
2007,
19.
Abstract:
The increase of integral emittance caused by Corkscrew motion in LIA is theoretically analyzed and numerically calculated in the paper. The simulation shows that the Corkscrew of beam centroid is a low frequency motion which overleaps the average eccentricity between centroid of beam and axis of accelerator and a dispersive effect. Although there are many common inspiriting factors, the Corkscrew motion and average eccentricity of beam centroid have absolutely different mechanism. The original inclined incidence and the energy spread of beam are the basic factors of Corkscrew motion. Magnetic field, magnetix axis tilt and assembly method influence obviously the amplitude and frequency of Corkscrew motion, and the growth of integral emittance. On the other hand, the eccentricity of beam cen
The increase of integral emittance caused by Corkscrew motion in LIA is theoretically analyzed and numerically calculated in the paper. The simulation shows that the Corkscrew of beam centroid is a low frequency motion which overleaps the average eccentricity between centroid of beam and axis of accelerator and a dispersive effect. Although there are many common inspiriting factors, the Corkscrew motion and average eccentricity of beam centroid have absolutely different mechanism. The original inclined incidence and the energy spread of beam are the basic factors of Corkscrew motion. Magnetic field, magnetix axis tilt and assembly method influence obviously the amplitude and frequency of Corkscrew motion, and the growth of integral emittance. On the other hand, the eccentricity of beam cen
2007,
19.
Abstract:
In order to investigate the spectrum effect in density gaining, an ideal radiography has been simualted with Monte Carlo (MC) method. Three kinds of mass attenuation coefficient(MAC) have been used, which are the monoenergetic MAC at the mean energy of the MC simulated spetrum, the effective MAC of the Born approximation formula spectrum(BS) and the effective MAC of the MC simulated spectrum. The results show that if the spectrum effective MAC is used, the spectrum effect decreases obviously. The root-mean-square error of the density may be less then 1.5% with the effective MAC of the BS. Better result is gained with the effective MAC of the MC simulated spectrum.
In order to investigate the spectrum effect in density gaining, an ideal radiography has been simualted with Monte Carlo (MC) method. Three kinds of mass attenuation coefficient(MAC) have been used, which are the monoenergetic MAC at the mean energy of the MC simulated spetrum, the effective MAC of the Born approximation formula spectrum(BS) and the effective MAC of the MC simulated spectrum. The results show that if the spectrum effective MAC is used, the spectrum effect decreases obviously. The root-mean-square error of the density may be less then 1.5% with the effective MAC of the BS. Better result is gained with the effective MAC of the MC simulated spectrum.
2007,
19.
Abstract:
Nanocrystalline material was chosen in the transformer design of the klystron modulator. The voltagecurrent vectors method was employed to measure the sample magnetic material, and the hysteresis curve, permeability and magnetic loss were obtained at frequencies of 20.03 kHz and 50 kHz. The magnetic capability of the large dimension toroid for application was measured by the pulse magnetization method. When the outer and inner dimensions of the toroid core were 220 and 80 mm, the hight was 60 mm, and the section was 4 200 mm2, the pulse width was 3.5~4.0 μs, the repelition rate was 50 Hz, the primary and second coils were 1 circle, the maximum voltsecond product was 0.007 V·s and the bias current was 8 A to maintain the toroid not saturated.
Nanocrystalline material was chosen in the transformer design of the klystron modulator. The voltagecurrent vectors method was employed to measure the sample magnetic material, and the hysteresis curve, permeability and magnetic loss were obtained at frequencies of 20.03 kHz and 50 kHz. The magnetic capability of the large dimension toroid for application was measured by the pulse magnetization method. When the outer and inner dimensions of the toroid core were 220 and 80 mm, the hight was 60 mm, and the section was 4 200 mm2, the pulse width was 3.5~4.0 μs, the repelition rate was 50 Hz, the primary and second coils were 1 circle, the maximum voltsecond product was 0.007 V·s and the bias current was 8 A to maintain the toroid not saturated.
2007,
19.
Abstract:
Based on the experiment on the Shenguang-Ⅱ，the damage of the phosphor and the micro-channel plate of the X-ray framing camera, induced by the vacuum-arc discharge, has been investigated. By measuring the position of the arc on the phosphor and the amplitude of the signal, three kinds of the arc discharges have been distinguished, they are scattered arc, strong arc and fixed arc charges. The damage of the imaging tube and the effect of the working state from the three arc discharges have been compared with different intensity and the different position, respectively. The discharge mechanism is explained with the electron field emission theory, and the stability of the damage is analyzed. The field enhanced coefficient of the fixed arc discharge has been deduced from the experiment result.
Based on the experiment on the Shenguang-Ⅱ，the damage of the phosphor and the micro-channel plate of the X-ray framing camera, induced by the vacuum-arc discharge, has been investigated. By measuring the position of the arc on the phosphor and the amplitude of the signal, three kinds of the arc discharges have been distinguished, they are scattered arc, strong arc and fixed arc charges. The damage of the imaging tube and the effect of the working state from the three arc discharges have been compared with different intensity and the different position, respectively. The discharge mechanism is explained with the electron field emission theory, and the stability of the damage is analyzed. The field enhanced coefficient of the fixed arc discharge has been deduced from the experiment result.
2007,
19.
Abstract:
MWIR HgCdTe photoconductive detectors were irradiated with 1Mrad gamma dose, the devices were annealed at different temperature from 313 K to 333 K for different baking time. The body resistance，responsivity，response spectrum and detectivity of the devices were measured before and after irradiation and in different ways of annealing. The responsivity and detectivity of devices declined under the same conditions. The effects of annealing on the performance of the devices during the whole experiment were observed. The experiments indicate that proper annealing steps can recovery the responsivity of the devices partly. The 323 K may be the best temperature for annealing.
MWIR HgCdTe photoconductive detectors were irradiated with 1Mrad gamma dose, the devices were annealed at different temperature from 313 K to 333 K for different baking time. The body resistance，responsivity，response spectrum and detectivity of the devices were measured before and after irradiation and in different ways of annealing. The responsivity and detectivity of devices declined under the same conditions. The effects of annealing on the performance of the devices during the whole experiment were observed. The experiments indicate that proper annealing steps can recovery the responsivity of the devices partly. The 323 K may be the best temperature for annealing.
2007,
19.
Abstract:
An optical spectroscopy based on Doppler shift is applied to measuring energy and the percentages of the four energy component—the full energy, half energy, third energy and the eighteenth energy of diagnostic neutral beam(DNB) on HT-7 Tokamak. According to the Doppler effect, the multi-peak Ha spectra is obtained, which are emitted by the neutral beam and separated from the unshifted Ha. Both the measurement principle and the data processing algorithm are presented in this paper. The experimental results of DNB show the percentages of the four energy component are 15%, 42%, 35% and 8% respectively.
An optical spectroscopy based on Doppler shift is applied to measuring energy and the percentages of the four energy component—the full energy, half energy, third energy and the eighteenth energy of diagnostic neutral beam(DNB) on HT-7 Tokamak. According to the Doppler effect, the multi-peak Ha spectra is obtained, which are emitted by the neutral beam and separated from the unshifted Ha. Both the measurement principle and the data processing algorithm are presented in this paper. The experimental results of DNB show the percentages of the four energy component are 15%, 42%, 35% and 8% respectively.
2007,
19.
Abstract:
The 96GeO-(3-χ)Al2O3-χNa2O-1NaBiO3 (molar fraction χ is 0,0.5,1.5, designated as A1, A2 and A3, respectively) and 96GeO-(3.5-ψ)Al2O3-ψNa2O-0.5Bi2O3(molar fraction ψ is 0.5,1,2, designated as B1, B2 and B3, respectively) glasses were prepared by conventional melting method. The near infrared superbroadband emission characteristics of the glasses were observed (peak at 1 220 nm) when pumped by an 800nm laser diode. The result indicated that doping of Bi5+ of NaBiO3 could increase the emission intensity of the glass in the infrared band by 4.6 times than that of Bi3+ of Bi2O3. The emission lifetime and the full width at half maximum(FWHM) at 1 220 nm increased from 280 μs, 195 nm to 434 μs, 275 nm, respectively. Meanwhile, the absorption edges of A3, A2, A1 were red-shifted. Thus, it
The 96GeO-(3-χ)Al2O3-χNa2O-1NaBiO3 (molar fraction χ is 0,0.5,1.5, designated as A1, A2 and A3, respectively) and 96GeO-(3.5-ψ)Al2O3-ψNa2O-0.5Bi2O3(molar fraction ψ is 0.5,1,2, designated as B1, B2 and B3, respectively) glasses were prepared by conventional melting method. The near infrared superbroadband emission characteristics of the glasses were observed (peak at 1 220 nm) when pumped by an 800nm laser diode. The result indicated that doping of Bi5+ of NaBiO3 could increase the emission intensity of the glass in the infrared band by 4.6 times than that of Bi3+ of Bi2O3. The emission lifetime and the full width at half maximum(FWHM) at 1 220 nm increased from 280 μs, 195 nm to 434 μs, 275 nm, respectively. Meanwhile, the absorption edges of A3, A2, A1 were red-shifted. Thus, it
2007,
19.
Abstract:
In order to realize less than 30 μm the pointing error of the main laser and the large focal spot irradiation uniform on target surface better than 10％ of the additional beam in “Shenguang-Ⅱ” laser facility, a physical design of final optics assembly(FOA) has been proposed. Using finite element method, the static and dynamic states about the main machine components of FOA and the integral ICF target chamber are analyzed and the design of FOA is optimized. And using mathematics simulation, lens array has been analyzed and designed based on the focus lens about unit number, radius, thickness, long axis and short axis. Experimental results show that the pointing error of main laser on the target is 28.9 μm , the large focal spot is 1 000 μm×500 μm and the large focal spot irradiation
In order to realize less than 30 μm the pointing error of the main laser and the large focal spot irradiation uniform on target surface better than 10％ of the additional beam in “Shenguang-Ⅱ” laser facility, a physical design of final optics assembly(FOA) has been proposed. Using finite element method, the static and dynamic states about the main machine components of FOA and the integral ICF target chamber are analyzed and the design of FOA is optimized. And using mathematics simulation, lens array has been analyzed and designed based on the focus lens about unit number, radius, thickness, long axis and short axis. Experimental results show that the pointing error of main laser on the target is 28.9 μm , the large focal spot is 1 000 μm×500 μm and the large focal spot irradiation
2007,
19.
Abstract:
X-ray is produced by SJ-A X-ray tube in China Academy of Measurement and Test Technology, Chengdu,and 80C196KC20 microprocessor is irradiated by X-ray in different directions. The direction is defined along the line which is perpenticular to the surface of the microprocessor. The results of the test show that the effect of X-ray to the microprocessor decreases while the angle changes from 0° to 90°. The main reason is that X-ray may go through different thickness of the crust of device when the device is irradiated in different directions.
X-ray is produced by SJ-A X-ray tube in China Academy of Measurement and Test Technology, Chengdu,and 80C196KC20 microprocessor is irradiated by X-ray in different directions. The direction is defined along the line which is perpenticular to the surface of the microprocessor. The results of the test show that the effect of X-ray to the microprocessor decreases while the angle changes from 0° to 90°. The main reason is that X-ray may go through different thickness of the crust of device when the device is irradiated in different directions.
2007,
19.
Abstract:
Silicon Carbide (SiC) is well known as an important optical material in aerospace optical system and high power laser optics. But the optical fabrication of SiC limits its usage widely. In this paper, domestic Chemical Gas Deposition (CVD) SiC material was polished by conventional optical fabrication method, in which ceramic disk and diamond powder were used to grind and lap, and then diamond oil with grain size from 4 μm to 1 μm was used to polish. After polishing nanometer scratches were found under AFM. 20 nm diameter Al2O3 alkali solution was used to continue to polish SiC surface and a surface roughness of 0.6 nm was achieved.
Silicon Carbide (SiC) is well known as an important optical material in aerospace optical system and high power laser optics. But the optical fabrication of SiC limits its usage widely. In this paper, domestic Chemical Gas Deposition (CVD) SiC material was polished by conventional optical fabrication method, in which ceramic disk and diamond powder were used to grind and lap, and then diamond oil with grain size from 4 μm to 1 μm was used to polish. After polishing nanometer scratches were found under AFM. 20 nm diameter Al2O3 alkali solution was used to continue to polish SiC surface and a surface roughness of 0.6 nm was achieved.
2007,
19.
Abstract:
Solid state pulse switch modules are developed for high power modulator. Internal semiconductor physical process and equivalent circuit of insulated gate bipolar transistor(IGBT) are analyzed. Based on power electronics simulation software Saber and its modeling tool, physical model of discrete chip IGBT IXDH 20N120 is implemented. With this model, output performance of pulse switch modules and solid state modulator with different circuit parameters and topologies is simulated. It turns out that dynamic voltage balance network could effectively protect switch modules and reduce IGBT switch’s power loss. On the other hand, random changes of trigger signal transmission delay time and stray capacitor in the circuit worsen the modulator’s output pulse quality and efficiency. The modulator’s
Solid state pulse switch modules are developed for high power modulator. Internal semiconductor physical process and equivalent circuit of insulated gate bipolar transistor(IGBT) are analyzed. Based on power electronics simulation software Saber and its modeling tool, physical model of discrete chip IGBT IXDH 20N120 is implemented. With this model, output performance of pulse switch modules and solid state modulator with different circuit parameters and topologies is simulated. It turns out that dynamic voltage balance network could effectively protect switch modules and reduce IGBT switch’s power loss. On the other hand, random changes of trigger signal transmission delay time and stray capacitor in the circuit worsen the modulator’s output pulse quality and efficiency. The modulator’s
2007,
19.
Abstract:
The response of photomultiplier tube(PMT) to scattered neutron and gamma ray is a severe interfere factor in low sensitivity scintillation neutron detection system. The response waveforms of PMT to 14.1 MeV pulse neutron is measured upon the ING-103 DPF pulse neutron source system, using two different types of PMT (EMI-9815B and EMI-9850B). To ensure the DPF source produce pulse neutron and X-ray simultaneously, it is essential to eliminate the X-ray’s interference. Through time of flight (TOF) method, the neutron and X-ray pulse are separated because of their different arriving time at the ulterior detection point. The net neutron pulse is detected by adding a Pb absorber in the beam channel to restrain the X-ray. The experimental sensitivity of the EMI-9815B and EMI-9850B are 10-13 and
The response of photomultiplier tube(PMT) to scattered neutron and gamma ray is a severe interfere factor in low sensitivity scintillation neutron detection system. The response waveforms of PMT to 14.1 MeV pulse neutron is measured upon the ING-103 DPF pulse neutron source system, using two different types of PMT (EMI-9815B and EMI-9850B). To ensure the DPF source produce pulse neutron and X-ray simultaneously, it is essential to eliminate the X-ray’s interference. Through time of flight (TOF) method, the neutron and X-ray pulse are separated because of their different arriving time at the ulterior detection point. The net neutron pulse is detected by adding a Pb absorber in the beam channel to restrain the X-ray. The experimental sensitivity of the EMI-9815B and EMI-9850B are 10-13 and
2007,
19.
Abstract:
In this paper a rail-like switch with multi-channel connected with parallel electrodes is designed and manufactured. The structure of the switch is illustrated and the internal electric field distribution is simulated by an electromagnetic simulation code. The voltage and current of the switch installed in the experiment setup are calculated using the software Pispice. Meanwhile experiments give the voltage and current of the switch, which are basically agreed with those from experiments. Experiments also indicate that the breakdown voltage of this switch is about 500 kV and the current of water-resistance of 1 kΩ is about 400 A. This work shows that this switch is compact and suitable to connect with parallel-plates transmission line.
In this paper a rail-like switch with multi-channel connected with parallel electrodes is designed and manufactured. The structure of the switch is illustrated and the internal electric field distribution is simulated by an electromagnetic simulation code. The voltage and current of the switch installed in the experiment setup are calculated using the software Pispice. Meanwhile experiments give the voltage and current of the switch, which are basically agreed with those from experiments. Experiments also indicate that the breakdown voltage of this switch is about 500 kV and the current of water-resistance of 1 kΩ is about 400 A. This work shows that this switch is compact and suitable to connect with parallel-plates transmission line.
2007,
19.
Abstract:
The turn-skipping of helical magnetic flux compression generators was analyzed, considering such factors as armature/stator eccentricity, non-uniform of armature surface and thickness, and detonation end effect, etc. Utilizing a more precise calculation model in which the space intersection curve of the expanding armature and the stator was taken into account, a more accurate formula of armature/stator eccentricity tolerance was developed and the conclusion is that the simplified calculation model is precise enough in practice to prevent the turn-skipping. Meanwhile, other factors such as the non-uniform of armature surface and thickness, and the detonation end effect which will also lead to the turn-skipping are also intensively analyzed and calculated. It is concluded that the length of
The turn-skipping of helical magnetic flux compression generators was analyzed, considering such factors as armature/stator eccentricity, non-uniform of armature surface and thickness, and detonation end effect, etc. Utilizing a more precise calculation model in which the space intersection curve of the expanding armature and the stator was taken into account, a more accurate formula of armature/stator eccentricity tolerance was developed and the conclusion is that the simplified calculation model is precise enough in practice to prevent the turn-skipping. Meanwhile, other factors such as the non-uniform of armature surface and thickness, and the detonation end effect which will also lead to the turn-skipping are also intensively analyzed and calculated. It is concluded that the length of
2007,
19.
Abstract:
This paper summarized the geometry and principle of the rod-pinch diode. Using Laminar model and considering the effect of background ion space charge on the one dimensional, Laminar equilibria of relativistic, magnetically self-insulated, electron flow is presented. Both positive and negative polarity diodes are simulated using MAGIC program, the current and voltage have also been solved through numerical simulation method. Results from numerical simulation are consistent with the calculations. In particular, it is shown that, as the voltage is the same, the self-pinch of negative rod-pinch diode is more difficult than that of the positive rod-pinch diode. Finally the characteristic impedance is detruded, the feasibility of laminar model has been validated.
This paper summarized the geometry and principle of the rod-pinch diode. Using Laminar model and considering the effect of background ion space charge on the one dimensional, Laminar equilibria of relativistic, magnetically self-insulated, electron flow is presented. Both positive and negative polarity diodes are simulated using MAGIC program, the current and voltage have also been solved through numerical simulation method. Results from numerical simulation are consistent with the calculations. In particular, it is shown that, as the voltage is the same, the self-pinch of negative rod-pinch diode is more difficult than that of the positive rod-pinch diode. Finally the characteristic impedance is detruded, the feasibility of laminar model has been validated.
