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RSS2008 Vol. 20, No. 06
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2008,
20.
Abstract:
A new method to perform the large aperture beams sampler with array-lens was put forward. An 25×25 array-lens of wavefront distortion measurement was designed, and an experimental system was settled up. The perfect parallel beam is used to demarcate the large aperture array-lens wavefront sampler. And a large aperture wavefront of distortion was measured by the set. That the experiment result is in accordance with the theoretical calculation.
A new method to perform the large aperture beams sampler with array-lens was put forward. An 25×25 array-lens of wavefront distortion measurement was designed, and an experimental system was settled up. The perfect parallel beam is used to demarcate the large aperture array-lens wavefront sampler. And a large aperture wavefront of distortion was measured by the set. That the experiment result is in accordance with the theoretical calculation.
2008,
20.
Abstract:
A model which combines drift-diffusion equation and heat transmission equation is established. Considering two laser absorption mechanics, including intrinsic carriers interband transition and free carriers inner-band transition, and the interaction of detector temperature and material properties, such as lifetime concentration mobility of carriers and absorption coefficient, the temperature responses in PC-type HgCdTe detector irradiated by in-band and outofband laser beams are calculated. The relationship between laser power density, irradiating time and the temperature rise is discussed．Results show that in-band laser irradiation can increase out-of-band laser absorption, and is an effective way to reduce damage thresholds.
A model which combines drift-diffusion equation and heat transmission equation is established. Considering two laser absorption mechanics, including intrinsic carriers interband transition and free carriers inner-band transition, and the interaction of detector temperature and material properties, such as lifetime concentration mobility of carriers and absorption coefficient, the temperature responses in PC-type HgCdTe detector irradiated by in-band and outofband laser beams are calculated. The relationship between laser power density, irradiating time and the temperature rise is discussed．Results show that in-band laser irradiation can increase out-of-band laser absorption, and is an effective way to reduce damage thresholds.
2008,
20.
Abstract:
Before making wind measurements, it is vital to calibrate the new developed Doppler wind lidar system, which can demonstrate and improve the validity of the lidar system. Based on the principle of wind measurement, a new method for the calibration of Rayleigh Doppler wind lidar taking advantage of the relationship between Rayleigh scattering spectrum and Mie scattering spectrum is proposed. This method uses a moving hard target to calibrate the Rayleigh Doppler wind lidar. The experimental system is designed for Rayleigh Doppler lidar calibration and the detailed processes are given as well.
Before making wind measurements, it is vital to calibrate the new developed Doppler wind lidar system, which can demonstrate and improve the validity of the lidar system. Based on the principle of wind measurement, a new method for the calibration of Rayleigh Doppler wind lidar taking advantage of the relationship between Rayleigh scattering spectrum and Mie scattering spectrum is proposed. This method uses a moving hard target to calibrate the Rayleigh Doppler wind lidar. The experimental system is designed for Rayleigh Doppler lidar calibration and the detailed processes are given as well.
2008,
20.
Abstract:
An ultrafast thermoelasticity model for the thermomechanical behaviors in semiconductors irradiated by ultra-short pulse laser is presented based on the complete self-consistent model. It accounts for the coupling effect between lattice temperature and strain rate, as well as for the hot-electron-blast effect in momentum transfer. A finite difference method is developed for solving the coupled, nonlinear, transient differential equations under uniaxial strain condition. Numerical analysis is performed for a 2 μm silicon film heated by a 500 fs laser pulse to obtain the temporal and spatial evolution of the carrier temperature and density, the lattice temperature, the thermal stress and the hot-electron blast force. The results show that the ultrafast thermoelasticity effect has very littl
An ultrafast thermoelasticity model for the thermomechanical behaviors in semiconductors irradiated by ultra-short pulse laser is presented based on the complete self-consistent model. It accounts for the coupling effect between lattice temperature and strain rate, as well as for the hot-electron-blast effect in momentum transfer. A finite difference method is developed for solving the coupled, nonlinear, transient differential equations under uniaxial strain condition. Numerical analysis is performed for a 2 μm silicon film heated by a 500 fs laser pulse to obtain the temporal and spatial evolution of the carrier temperature and density, the lattice temperature, the thermal stress and the hot-electron blast force. The results show that the ultrafast thermoelasticity effect has very littl
2008,
20.
Abstract:
Ellipsometry of light scattering from optical thin films are investigated based on reflection ellipsometry measurements from optical thin films. The inverse problem of light scattering from optical films is solved with this method. Diamond-like carbon(DLC) films deposited by pulse vacuum arc ion coating technology with different pulse frequency are studied. The effects of correlation and localized defects in films on scattering ellipsometry are emphasized. The results show that correlation become worse and scattering become more obvious as the pulse frequency increases in depositing DLC films.
Ellipsometry of light scattering from optical thin films are investigated based on reflection ellipsometry measurements from optical thin films. The inverse problem of light scattering from optical films is solved with this method. Diamond-like carbon(DLC) films deposited by pulse vacuum arc ion coating technology with different pulse frequency are studied. The effects of correlation and localized defects in films on scattering ellipsometry are emphasized. The results show that correlation become worse and scattering become more obvious as the pulse frequency increases in depositing DLC films.
2008,
20.
Abstract:
Directly etching an active grating in Er/Yb codoped fiber, a compact asymmetric π phase-shifted fiber laser was fabricated. The designed grating length is only 50 mm, the optimal phase shift position is at 29 mm, and the optimal coupling coefficient value is 150 m－1 . Adopting forward pumped manner by 980 nm LD, when pumped power was of 200 mW, at 1 550.94 nm we have achieved the narrow-band laser output of 10 mW, its width was narrower than 0.05 nm, the threshold was 35 mW, the slope efficiency was 6.06%, total optical conversion efficiency was 5%. The fiber laser has met the practicality of light sources' power in the long-term optical communications system．
Directly etching an active grating in Er/Yb codoped fiber, a compact asymmetric π phase-shifted fiber laser was fabricated. The designed grating length is only 50 mm, the optimal phase shift position is at 29 mm, and the optimal coupling coefficient value is 150 m－1 . Adopting forward pumped manner by 980 nm LD, when pumped power was of 200 mW, at 1 550.94 nm we have achieved the narrow-band laser output of 10 mW, its width was narrower than 0.05 nm, the threshold was 35 mW, the slope efficiency was 6.06%, total optical conversion efficiency was 5%. The fiber laser has met the practicality of light sources' power in the long-term optical communications system．
2008,
20.
Abstract:
HfO2 films were prepared by electron beam evaporation on K9 glass. Oxygen flux was varied in the range of 0 mL/min to 25 mL/min by step of 5 mL/min (under standard condition). The residual stress was measured by viewing the substrate deflection using ZYGO interferometer. The results show that, as the oxygen pressure increases, the residual stresses decrease gradually from tensile to compressive, and then increase. The changes may be due to the variation of the microstructure of the HfO2 films, which was inspected with X-ray diffraction(XRD). The finite element software ansys was used to calculate the substrate deflection which was then compared with the measured data. The comparison proves that our model is right and it helps to conduct analyses on HfO2/SiO2 stack stresses.
HfO2 films were prepared by electron beam evaporation on K9 glass. Oxygen flux was varied in the range of 0 mL/min to 25 mL/min by step of 5 mL/min (under standard condition). The residual stress was measured by viewing the substrate deflection using ZYGO interferometer. The results show that, as the oxygen pressure increases, the residual stresses decrease gradually from tensile to compressive, and then increase. The changes may be due to the variation of the microstructure of the HfO2 films, which was inspected with X-ray diffraction(XRD). The finite element software ansys was used to calculate the substrate deflection which was then compared with the measured data. The comparison proves that our model is right and it helps to conduct analyses on HfO2/SiO2 stack stresses.
2008,
20.
Abstract:
In methane-hydrogen and methane-helium systems, optical emission spectroscopy(OES) is used to diagnose the active species emission in the low-pressure methane plasma by spiral wave discharge. In experiments, the main species as H(Ha, Hb, Hg) and CH have been identified in the two systems. In CH4/He system, the intensities of these active species first increased and then decreased with the increase of the input RF power, and as the gas pressure increased, the intensity of the CH radical decreased, the intensities of Ha, Hb and Hg species initially increased and then decreased. In CH4/H2 system, the relative intensities of Ha, Hb, Hg and CH radicals increased with the increase of the input RF power, and the relative intensities of all these radicals initially increased and then decreased wit
In methane-hydrogen and methane-helium systems, optical emission spectroscopy(OES) is used to diagnose the active species emission in the low-pressure methane plasma by spiral wave discharge. In experiments, the main species as H(Ha, Hb, Hg) and CH have been identified in the two systems. In CH4/He system, the intensities of these active species first increased and then decreased with the increase of the input RF power, and as the gas pressure increased, the intensity of the CH radical decreased, the intensities of Ha, Hb and Hg species initially increased and then decreased. In CH4/H2 system, the relative intensities of Ha, Hb, Hg and CH radicals increased with the increase of the input RF power, and the relative intensities of all these radicals initially increased and then decreased wit
2008,
20.
Abstract:
Based on the effective Fresnel number, a simple analytical expression is presented to evaluate the relative focal shift in a circular-aperture lens system which is illuminated by a partially coherent electromagnetic beam. The effective Fresnel number is dependent not only on real Fresnel number but also on the polarization distribution and spatial coherent lengths of two polarized components of the incident partially coherent electromagnetic beam. It is shown that the relative focal shift is just determined by the effective Fresnel number. The results indicate that this new method can evaluate the focal shifts simply and exactly.
Based on the effective Fresnel number, a simple analytical expression is presented to evaluate the relative focal shift in a circular-aperture lens system which is illuminated by a partially coherent electromagnetic beam. The effective Fresnel number is dependent not only on real Fresnel number but also on the polarization distribution and spatial coherent lengths of two polarized components of the incident partially coherent electromagnetic beam. It is shown that the relative focal shift is just determined by the effective Fresnel number. The results indicate that this new method can evaluate the focal shifts simply and exactly.
2008,
20.
Abstract:
In the output image of the visible light CCD irradiated by high intensity light, black area appears inside the white saturation scope. In this paper, the phenomenon is called excessive saturation effect of visible light CCD. In the experiment during which excessive saturation effect occurs, there are four basic waveforms. The course of signal processing of the CCD camera system is introduced, in which the correlated double sampling is indispensable for reducing some noise of output signal of CCD. Corresponding to the four basic waveforms, the output results of correlated double sampling(CDS) are given, which bring four basic areas (black area, gray area, saturated white area, excessively saturated black area) in output image of CCD. In waveform corresponding to the excessively saturated b
In the output image of the visible light CCD irradiated by high intensity light, black area appears inside the white saturation scope. In this paper, the phenomenon is called excessive saturation effect of visible light CCD. In the experiment during which excessive saturation effect occurs, there are four basic waveforms. The course of signal processing of the CCD camera system is introduced, in which the correlated double sampling is indispensable for reducing some noise of output signal of CCD. Corresponding to the four basic waveforms, the output results of correlated double sampling(CDS) are given, which bring four basic areas (black area, gray area, saturated white area, excessively saturated black area) in output image of CCD. In waveform corresponding to the excessively saturated b
2008,
20.
Abstract:
By using the beam coherence-polarization(BCP) matrix method, the expressions for the degree of polarization and intensity of nonuniformly polarized(NUP) beams propagating through an annular aperture are derived, which enable to study the changes in the degree of polarization and intensity of NUP beams propagating through the annular aperture. It is shown that, the degree of polarization is usually nonuniform, but is nearly uniform in the central region at the transversal plane, which depends on the NUP beam parameters, obscure ratio of the aperture and propagation distance. The uniform intensity of NUP beams becomes non-uniform with a central principal maximum and small diffraction side lobes after passing through the aperture.
By using the beam coherence-polarization(BCP) matrix method, the expressions for the degree of polarization and intensity of nonuniformly polarized(NUP) beams propagating through an annular aperture are derived, which enable to study the changes in the degree of polarization and intensity of NUP beams propagating through the annular aperture. It is shown that, the degree of polarization is usually nonuniform, but is nearly uniform in the central region at the transversal plane, which depends on the NUP beam parameters, obscure ratio of the aperture and propagation distance. The uniform intensity of NUP beams becomes non-uniform with a central principal maximum and small diffraction side lobes after passing through the aperture.
2008,
20.
Abstract:
In indirect-driven inertial confinement fusion(ICF), the hohlraum’s non-equilibrium radiation field brings an unneglectable impact to the ablation process of the capsule’s ablator materials(CH, e.g.). In this paper, an artificial spectrum of the hohlraum’s radiation field is fabricated by combining the Planckian spectrum with a Gaussian spectrum near Au M-band. A CH foil ablated by such a radiation source is simulated, and the influence of non-equilibrium radiation field on physical quantities (ablation pressure, preheating, compression ratio, shock velocity,etc)of the ablation process is studied, using a 1D radiation hydrodynamics code RDMG with discrete ordinate approximation(Sn). The simulation results show that the Au M-band radiation in the hohlraum remarkably increases the preheat
In indirect-driven inertial confinement fusion(ICF), the hohlraum’s non-equilibrium radiation field brings an unneglectable impact to the ablation process of the capsule’s ablator materials(CH, e.g.). In this paper, an artificial spectrum of the hohlraum’s radiation field is fabricated by combining the Planckian spectrum with a Gaussian spectrum near Au M-band. A CH foil ablated by such a radiation source is simulated, and the influence of non-equilibrium radiation field on physical quantities (ablation pressure, preheating, compression ratio, shock velocity,etc)of the ablation process is studied, using a 1D radiation hydrodynamics code RDMG with discrete ordinate approximation(Sn). The simulation results show that the Au M-band radiation in the hohlraum remarkably increases the preheat
2008,
20.
Abstract:
Mesoporous SiO2 film with 2D p6 mm structure was successfully coated on K9 glasses via the hydrolysis-condensation process and the so-called evaporation induced self-assembly process using P123 as a surfactant. The structure and optical properties of the film were characterized with FT-IR,XRD,N2 adsorption-desorption,AFM and UV-Vis. The laser-induced damage threshold of the film was tested with “R-on-1” model on Nd:YAG laser(9.2 ns, 1 064 nm). The as-prepared single-layer mesoporous SiO2 film was proved to have ordered 2D p6 mm structure, SBA-15 type and average roughness of 2.923 nm. The film showed high trassimittance of 99.6% at the wavelength of 1 064 nm. The laser-induced damage threshold was 21.6 J/cm2 when the laser pulse was 1 ns, at wavelength of 1 064 nm.
Mesoporous SiO2 film with 2D p6 mm structure was successfully coated on K9 glasses via the hydrolysis-condensation process and the so-called evaporation induced self-assembly process using P123 as a surfactant. The structure and optical properties of the film were characterized with FT-IR,XRD,N2 adsorption-desorption,AFM and UV-Vis. The laser-induced damage threshold of the film was tested with “R-on-1” model on Nd:YAG laser(9.2 ns, 1 064 nm). The as-prepared single-layer mesoporous SiO2 film was proved to have ordered 2D p6 mm structure, SBA-15 type and average roughness of 2.923 nm. The film showed high trassimittance of 99.6% at the wavelength of 1 064 nm. The laser-induced damage threshold was 21.6 J/cm2 when the laser pulse was 1 ns, at wavelength of 1 064 nm.
2008,
20.
Abstract:
The sol-gel monolayer silica acid and basic thin films on K9 glass substrates were prepared with the dip method from acid and basic catalyzed silica sols, respectively. Both films have nearly similar optical thickness. The laser-induced damage thresholds(LIDT) of the two kinds of films were measured. Thermal absorption, porous ratio and surface morphologies of films were investigated by Stanford photo-thermal solutions, ellipsometer, atomic force microscope(AFM) and scanning electron microscope(SEM), respectively. Optical microscope was used to characterize the defects and impurities of films before laser irradiation and damage morphology after laser irradiation. The experimental results showed that compared with basic film, the silica acid film had larger absorption, smaller porous ratio
The sol-gel monolayer silica acid and basic thin films on K9 glass substrates were prepared with the dip method from acid and basic catalyzed silica sols, respectively. Both films have nearly similar optical thickness. The laser-induced damage thresholds(LIDT) of the two kinds of films were measured. Thermal absorption, porous ratio and surface morphologies of films were investigated by Stanford photo-thermal solutions, ellipsometer, atomic force microscope(AFM) and scanning electron microscope(SEM), respectively. Optical microscope was used to characterize the defects and impurities of films before laser irradiation and damage morphology after laser irradiation. The experimental results showed that compared with basic film, the silica acid film had larger absorption, smaller porous ratio
2008,
20.
Abstract:
SiO2 thin films were deposited using tetraethoxylsilane as precursor, ammonia as catalyst on K9 glass by sol-gel method. These films were post-treated by ammonia and heat. The properties of the coatings were characterized by ellipsometer, UV-vis spectrophotometry, FTIR-spectroscopy, scanning probe microscope and contact angle measurement apparatus. The results indicate that the thickness of the films with ammonia and heat treatment tend to decrease. Both the refractive index and water contact angle increase after ammonia treatment. However, they both decrease after heat treatment. The former increases by 0.236 for the first step, then decreases by 0.202 for the second. The latter increases to 58.92°, then decreases to 38.07°. The transmittance of the coatings turn to be better and contin
SiO2 thin films were deposited using tetraethoxylsilane as precursor, ammonia as catalyst on K9 glass by sol-gel method. These films were post-treated by ammonia and heat. The properties of the coatings were characterized by ellipsometer, UV-vis spectrophotometry, FTIR-spectroscopy, scanning probe microscope and contact angle measurement apparatus. The results indicate that the thickness of the films with ammonia and heat treatment tend to decrease. Both the refractive index and water contact angle increase after ammonia treatment. However, they both decrease after heat treatment. The former increases by 0.236 for the first step, then decreases by 0.202 for the second. The latter increases to 58.92°, then decreases to 38.07°. The transmittance of the coatings turn to be better and contin
2008,
20.
Abstract:
THz radiation excited from the laser-plasma interaction was numerically simulated using a 2D3V PIC code, and the effects of laser parameters on the THz radiation power and frequency were compared with the results of the linear mode conversion theory. The PIC simulation results show that the laser pulse intensity dominates on the THz radiation power; the optimal pulse width for the strongest electrostatic wave with THz radiation is around the plasma wavelength. Meanwhile, there is an optimal focused radius which is around 0.35gp0 for the strongest radiation.
THz radiation excited from the laser-plasma interaction was numerically simulated using a 2D3V PIC code, and the effects of laser parameters on the THz radiation power and frequency were compared with the results of the linear mode conversion theory. The PIC simulation results show that the laser pulse intensity dominates on the THz radiation power; the optimal pulse width for the strongest electrostatic wave with THz radiation is around the plasma wavelength. Meanwhile, there is an optimal focused radius which is around 0.35gp0 for the strongest radiation.
2008,
20.
Abstract:
The picosecond gated characteristics of X-ray framing camera at different DC bias are examined using sub-ps X-ray source produced by SILEX-Ⅰ facility. The point-source measurement of XFC exposure-time is set up. The dynamic gain is defined based on the XFC principium. The experiment shows that the widening of exposure-time is 10 ps at DC bias of -100 V, and the dynamic gain increases by a factor of 3.5. The amplitude of exposure-amount measured is on the high side at DC negative bias. It is possible that the DC bias influences the dynamics of original photoelectrons, and induces dynamic gain exaltation.
The picosecond gated characteristics of X-ray framing camera at different DC bias are examined using sub-ps X-ray source produced by SILEX-Ⅰ facility. The point-source measurement of XFC exposure-time is set up. The dynamic gain is defined based on the XFC principium. The experiment shows that the widening of exposure-time is 10 ps at DC bias of -100 V, and the dynamic gain increases by a factor of 3.5. The amplitude of exposure-amount measured is on the high side at DC negative bias. It is possible that the DC bias influences the dynamics of original photoelectrons, and induces dynamic gain exaltation.
2008,
20.
Abstract:
The transient collisional excited Ni-like Ag 13.9 nm X-ray laser was simulated. Driven by two picosecond short pulses preceded by a 330 ps long prepulse, different short pulses of 1 ps, 2 ps and 3 ps were considered and for each case the angular characteristics of the output X-ray laser are presented in this paper. Detailed analysis shows that the (330 ps,1 ps,1 ps) pumping combinations delayed by about 500 ps can extract higher gains near critical surface and it works best. To get the effect of the first short pulse, X-ray lasers driven by only one short pulse following the same long prepulse was simulated and optimization was made. By comparing the optimized case of the two pumping scheme, the advantages of the two short pulses pumping scheme was indicated.
The transient collisional excited Ni-like Ag 13.9 nm X-ray laser was simulated. Driven by two picosecond short pulses preceded by a 330 ps long prepulse, different short pulses of 1 ps, 2 ps and 3 ps were considered and for each case the angular characteristics of the output X-ray laser are presented in this paper. Detailed analysis shows that the (330 ps,1 ps,1 ps) pumping combinations delayed by about 500 ps can extract higher gains near critical surface and it works best. To get the effect of the first short pulse, X-ray lasers driven by only one short pulse following the same long prepulse was simulated and optimization was made. By comparing the optimized case of the two pumping scheme, the advantages of the two short pulses pumping scheme was indicated.
2008,
20.
Abstract:
Five experiments were introduced in this paper, which were about the effects of the characteristic X-ray of impurity elements on the generation of four new spectral lines of hydrogen gas discharge source bombarding famget. Shield-Experiment and Intense-Electron Radiation Experiment verified new spectral lines are not the characteristic X-ray of impurity elements’ from discharging chamber. The Polish-Experiment verified that the new spectral lines are not produced by impurity elements. It was verified that all impurity in target have no effect on the generation of the new spectral lines by the resonant spectral line and the law that the spectral line's intensity varies with the discharging voltage. Five experiments prove that the new spectral lines are not any characteristic X-ray of impur
Five experiments were introduced in this paper, which were about the effects of the characteristic X-ray of impurity elements on the generation of four new spectral lines of hydrogen gas discharge source bombarding famget. Shield-Experiment and Intense-Electron Radiation Experiment verified new spectral lines are not the characteristic X-ray of impurity elements’ from discharging chamber. The Polish-Experiment verified that the new spectral lines are not produced by impurity elements. It was verified that all impurity in target have no effect on the generation of the new spectral lines by the resonant spectral line and the law that the spectral line's intensity varies with the discharging voltage. Five experiments prove that the new spectral lines are not any characteristic X-ray of impur
2008,
20.
Abstract:
By analyzing time resolution of radiation temperature measurement, the main factors of systemic bias, cable’s length and bandwidth, attenuator’s bandwidth, oscillograph’s bandwidth and sampling rate have been determined. To improve the systemic time resolution, the system bias was increased to 3 kV, the cable length was shortened to 2 m, an attenuator with higher bandwidth(18 GHz) and an oscillograph with higher bandwidth(6 GHz) and sampling rate(22×1010／s) were used. Then, in Silex-Ⅰ laser , the systemic time resolution was measured, the systemic risetime is 130 ps, and the time resolution is 215 ps. Using this system, in the experiment on Shenguang-Ⅱ facility in Shanghai, the radiation temperature measurement of cavity target was carried out, and time resolution better than 215
By analyzing time resolution of radiation temperature measurement, the main factors of systemic bias, cable’s length and bandwidth, attenuator’s bandwidth, oscillograph’s bandwidth and sampling rate have been determined. To improve the systemic time resolution, the system bias was increased to 3 kV, the cable length was shortened to 2 m, an attenuator with higher bandwidth(18 GHz) and an oscillograph with higher bandwidth(6 GHz) and sampling rate(22×1010／s) were used. Then, in Silex-Ⅰ laser , the systemic time resolution was measured, the systemic risetime is 130 ps, and the time resolution is 215 ps. Using this system, in the experiment on Shenguang-Ⅱ facility in Shanghai, the radiation temperature measurement of cavity target was carried out, and time resolution better than 215
2008,
20.
Abstract:
For the research of X-ray spectrum of Z-pinch plasma, a wide variety of X-ray and extreme ultraviolet diagnostics are being developed to study on Yang accelerator. An elliptical curved crystal spectrometer was designed and the spectrograph has 1 350 mm focal length and for these measurements, a mica crystal bent onto an elliptical substrate was utilized with an eccentricity e=0.948 5. The crystal analyzer covers the Bragg angel ranging from 30° to 60°. The ability of the mica crystal to efficiently reflect radiation in multiple orders allowed us to cover the entire spectral range from 0.10 to 1.73 nm except for a gap from 0.86 to 1.00 nm. The experiment was carried out on Yang accelerator and aimed to investigate the characteristics of a high density plasma. Experimental results using cu
For the research of X-ray spectrum of Z-pinch plasma, a wide variety of X-ray and extreme ultraviolet diagnostics are being developed to study on Yang accelerator. An elliptical curved crystal spectrometer was designed and the spectrograph has 1 350 mm focal length and for these measurements, a mica crystal bent onto an elliptical substrate was utilized with an eccentricity e=0.948 5. The crystal analyzer covers the Bragg angel ranging from 30° to 60°. The ability of the mica crystal to efficiently reflect radiation in multiple orders allowed us to cover the entire spectral range from 0.10 to 1.73 nm except for a gap from 0.86 to 1.00 nm. The experiment was carried out on Yang accelerator and aimed to investigate the characteristics of a high density plasma. Experimental results using cu
2008,
20.
Abstract:
MCP transmissivity is calibrated on the 3B3 medium energy X-ray beamline in BSRF from 2.0~5.5 keV. The experimental result unveils that the transmissivity shrinks steeply from 2.0~3.5 keV, and reaches the bottom from 3.5~4.5 keV,then swells from 4.5~5.5 keV. MCP transmissivity near the two ends of low-energy 2 keV and high-energy 5.5 keV is higher than that at the middle part. Reflection and transmission are calculated in the pores array of MCP respectively. The grazing incident X-ray in pores results in total reflection, and the reflectivity rises as the X-ray energy falls, which successfully explains the peculiar phenomena of high transmissivity in low energy. Characteristic of MCP transmissivity is resulted from peculiar structure and material of the MCP, and is contributed together by
MCP transmissivity is calibrated on the 3B3 medium energy X-ray beamline in BSRF from 2.0~5.5 keV. The experimental result unveils that the transmissivity shrinks steeply from 2.0~3.5 keV, and reaches the bottom from 3.5~4.5 keV,then swells from 4.5~5.5 keV. MCP transmissivity near the two ends of low-energy 2 keV and high-energy 5.5 keV is higher than that at the middle part. Reflection and transmission are calculated in the pores array of MCP respectively. The grazing incident X-ray in pores results in total reflection, and the reflectivity rises as the X-ray energy falls, which successfully explains the peculiar phenomena of high transmissivity in low energy. Characteristic of MCP transmissivity is resulted from peculiar structure and material of the MCP, and is contributed together by
2008,
20.
Abstract:
Hot dispersion equation is derived and solved of the slow-wave structure(SWS) of the corrugated-inner-conductor backward-wave oscillator(CICBWO), the particle-in-cell(PIC) model is constructed and calculated by PIC code. The results suggest an high frequency microwave is obtained with a frequency of 10 GHz, an average output power of 1.1 GW and a power efficiency of 25% when the acceleration voltage is 0.5 MV, the electronic current 8.5 kA, the corrugated period 4.4 cm, the corrugated magnitude 0.23 cm, the inner radius 2.9 cm and the inner radius of the outside wall 4.4 cm.
Hot dispersion equation is derived and solved of the slow-wave structure(SWS) of the corrugated-inner-conductor backward-wave oscillator(CICBWO), the particle-in-cell(PIC) model is constructed and calculated by PIC code. The results suggest an high frequency microwave is obtained with a frequency of 10 GHz, an average output power of 1.1 GW and a power efficiency of 25% when the acceleration voltage is 0.5 MV, the electronic current 8.5 kA, the corrugated period 4.4 cm, the corrugated magnitude 0.23 cm, the inner radius 2.9 cm and the inner radius of the outside wall 4.4 cm.
2008,
20.
Abstract:
Rogowski coil is used quite widely in measuring pulse current for its simple structure and good response in high frequency. In this paper，principle of using two self-integral Rogowski coils for radial electronic beam current measurement is analysed, and the Rogowski coils are calibrated by standard current. The calibrated results show that the diagnostic system could get the signal with response time less than 10ns and error about 4.7% when the rising edge of the standard current is 30ns and the system can meet the requirements of nanosecond beam measurement. Therefore, it can be used for measuring the intensity of a radial electronic beam eradiated by high-power microwave devices．
Rogowski coil is used quite widely in measuring pulse current for its simple structure and good response in high frequency. In this paper，principle of using two self-integral Rogowski coils for radial electronic beam current measurement is analysed, and the Rogowski coils are calibrated by standard current. The calibrated results show that the diagnostic system could get the signal with response time less than 10ns and error about 4.7% when the rising edge of the standard current is 30ns and the system can meet the requirements of nanosecond beam measurement. Therefore, it can be used for measuring the intensity of a radial electronic beam eradiated by high-power microwave devices．
2008,
20.
Abstract:
Ablative capillary discharge plasma jets are characterized by high density and relatively low temperature. The devices of this kind of plasma jets are of importance to a variety of applications. Two-gap capillary plasma generator(TGCPG) is a realistic alternative to the conventional capillary in electrothermal launchers and a versatile capillary plasma generator for other applications. A one-dimensional hydrodynamic model considers which the ohmic heating and wall ablation is proposed for calculating the properties of plasma arcs of the main discharges in TGCPG. The calculation shows that the discharge is in a quasi-steady state, the plasma temperature keeps stable during the discharge while the mass density and pressure are drastically changed. With 1 kJ discharge energy, a plasma jet wit
Ablative capillary discharge plasma jets are characterized by high density and relatively low temperature. The devices of this kind of plasma jets are of importance to a variety of applications. Two-gap capillary plasma generator(TGCPG) is a realistic alternative to the conventional capillary in electrothermal launchers and a versatile capillary plasma generator for other applications. A one-dimensional hydrodynamic model considers which the ohmic heating and wall ablation is proposed for calculating the properties of plasma arcs of the main discharges in TGCPG. The calculation shows that the discharge is in a quasi-steady state, the plasma temperature keeps stable during the discharge while the mass density and pressure are drastically changed. With 1 kJ discharge energy, a plasma jet wit
2008,
20.
Abstract:
A capacitance-resistance coupling UV illumination switch under 300 kV breakdown pulse voltage was designed and studied. The UV illumination structure and circuit parameter are important to the design of the switch. The simulation results indicated that the breakdown matching between UV gap and switch could be achieved with an appropriate capacitance-resistance coupling circuit. Experimental results indicated that the UV illumination time was adjusted effectively when resistance was changed within a certain range. Accordingly, the jitter of the UV illumination switch was decreased by adapting the UV illumination time for the pulse voltage. The jitter of the UV illumination switch was less than 3 ns under pulse voltage with 240 ns risetime , and less than 2 ns under pulse voltage with 36 ns
A capacitance-resistance coupling UV illumination switch under 300 kV breakdown pulse voltage was designed and studied. The UV illumination structure and circuit parameter are important to the design of the switch. The simulation results indicated that the breakdown matching between UV gap and switch could be achieved with an appropriate capacitance-resistance coupling circuit. Experimental results indicated that the UV illumination time was adjusted effectively when resistance was changed within a certain range. Accordingly, the jitter of the UV illumination switch was decreased by adapting the UV illumination time for the pulse voltage. The jitter of the UV illumination switch was less than 3 ns under pulse voltage with 240 ns risetime , and less than 2 ns under pulse voltage with 36 ns
2008,
20.
Abstract:
The effect of vacuum ultraviolet (VUV) irradiation on the surface morphology, mass loss, thermal properties and optical property of the additional silicone rubber reinforced with MQ resin was studied by space combined radiation simulator. The results showed that the aging crackle was produced on the surface of rubber after irradiation and the quantity of the crackle increased with the increase of irradiation dose. There was mass loss of the silicone rubber after VUV irradiation and the mass loss percentage increased with the increase of irradiation dose. The thermostability of the silicone rubber increased firstly and then decreased with the increase of irradiation dose. The VUV irradiation had little effect on the body inflation/shrinkage distortion of the silicone rubber, but it had sign
The effect of vacuum ultraviolet (VUV) irradiation on the surface morphology, mass loss, thermal properties and optical property of the additional silicone rubber reinforced with MQ resin was studied by space combined radiation simulator. The results showed that the aging crackle was produced on the surface of rubber after irradiation and the quantity of the crackle increased with the increase of irradiation dose. There was mass loss of the silicone rubber after VUV irradiation and the mass loss percentage increased with the increase of irradiation dose. The thermostability of the silicone rubber increased firstly and then decreased with the increase of irradiation dose. The VUV irradiation had little effect on the body inflation/shrinkage distortion of the silicone rubber, but it had sign
2008,
20.
Abstract:
The TiNbN hard film have been prepared on high-speed steel by arc ion-plating using seperate targets. The prepared film are irradiated by high-intensity pulsed ion beam(HIPIB) of mixing proton and carbon ions at accelerating voltage of 300 kV with pulse width of 70 ns, at ion current density of 60 A/cm2 on TEMP-6 type HIPIB apparatus. The friction and wear behaviors of non-irradiated and irradiated film are investigated under loads of 300 N and 600 N, respectively. The HIPIB irradiation leads to grain size reduction of the film, by which the hardness of film is enhanced from HK3444 to HK3820, and the bonding strength between film and substrate increases from 59 N to 65 N. The irradiated film has significant improvements in friction and wear characteristics．
The TiNbN hard film have been prepared on high-speed steel by arc ion-plating using seperate targets. The prepared film are irradiated by high-intensity pulsed ion beam(HIPIB) of mixing proton and carbon ions at accelerating voltage of 300 kV with pulse width of 70 ns, at ion current density of 60 A/cm2 on TEMP-6 type HIPIB apparatus. The friction and wear behaviors of non-irradiated and irradiated film are investigated under loads of 300 N and 600 N, respectively. The HIPIB irradiation leads to grain size reduction of the film, by which the hardness of film is enhanced from HK3444 to HK3820, and the bonding strength between film and substrate increases from 59 N to 65 N. The irradiated film has significant improvements in friction and wear characteristics．
2008,
20.
Abstract:
A sliding mode variable structure control method was studied for controlling beam halo-chaos in the periodic focusing channels(PFCs) of high-current ion accelerator. The sliding mode variable structure controller based on Lyapunov function theory was presented. The analysis and simulation results demonstrate that the chaotic radius of envelope can be controlled to the matched radius via adjusting exterior focusing magnetic field. This method was also applied to the multi-particle model of the beam with the K-V distribution in the PFCs. Under the mono-periodical interval control condition, the average transverse emittances of ion beam was decreased by about 80%, the beam halos and its regeneration could be eliminated, the qualities of high current beam become better. This method is easy to
A sliding mode variable structure control method was studied for controlling beam halo-chaos in the periodic focusing channels(PFCs) of high-current ion accelerator. The sliding mode variable structure controller based on Lyapunov function theory was presented. The analysis and simulation results demonstrate that the chaotic radius of envelope can be controlled to the matched radius via adjusting exterior focusing magnetic field. This method was also applied to the multi-particle model of the beam with the K-V distribution in the PFCs. Under the mono-periodical interval control condition, the average transverse emittances of ion beam was decreased by about 80%, the beam halos and its regeneration could be eliminated, the qualities of high current beam become better. This method is easy to
2008,
20.
Abstract:
A Monte-Carlo simulation was done to study the influence of the internal pellet and carbon foil target to the beam in the CSRm without electron cooling. The results show that the beam loss is mainly due to the growth of beam emittance caused by the small angle Coulomb scattering in the target, and lifetime of the beam is proportional to the beam energy and inverse proportional to the target thickness. For 2.6 GeV proton beam, lifetime in the CSRm is about 100 s with pellet target(1×1016 atoms×cm-2) and will drop to 1 s with carbon foil target(5×1017 atoms×cm-2).
A Monte-Carlo simulation was done to study the influence of the internal pellet and carbon foil target to the beam in the CSRm without electron cooling. The results show that the beam loss is mainly due to the growth of beam emittance caused by the small angle Coulomb scattering in the target, and lifetime of the beam is proportional to the beam energy and inverse proportional to the target thickness. For 2.6 GeV proton beam, lifetime in the CSRm is about 100 s with pellet target(1×1016 atoms×cm-2) and will drop to 1 s with carbon foil target(5×1017 atoms×cm-2).
2008,
20.
Abstract:
The Kapchinsky-Vladimirsky (K-V) beam through an axisymmetric periodic-focusing magnetic field is studied using the particle-core model. The beam halo-chaos is found, and a real Morlet wavelet function controller is proposed based on the mechanism of halo formation and the strategy of controlling halo-chaos. The method is applied to the multi-particle simulation to control the halo. The numerical results show that the halo-chaos and its regeneration can be eliminated effectively by using the real Morlet wavelet function control method. At the same time, the radial particle density is uniform at the center of the beam as long as the control method and appropriate parameter are chosen.
The Kapchinsky-Vladimirsky (K-V) beam through an axisymmetric periodic-focusing magnetic field is studied using the particle-core model. The beam halo-chaos is found, and a real Morlet wavelet function controller is proposed based on the mechanism of halo formation and the strategy of controlling halo-chaos. The method is applied to the multi-particle simulation to control the halo. The numerical results show that the halo-chaos and its regeneration can be eliminated effectively by using the real Morlet wavelet function control method. At the same time, the radial particle density is uniform at the center of the beam as long as the control method and appropriate parameter are chosen.
2008,
20.
Abstract:
The factors on pulsed vacuum flashover of epoxy composite filled with micro-scale Al2O3·3H2O particles are studied. The effects of coupling agent, dispersion method, curing agent, and surface roughness on the flashover properties are investigated respectively. Compared with the amine curing agent, the casting epoxy resin cured by the acid anhydride has higher flashover voltage. The epoxy composite matrix dispersed by the high shear force has better disperse effect compared with that dispersed by the ultrasonic dispersion method. Epoxy composite filled with micro-scale particles treated by coupling agent has higher flashover voltage than that without coupling agent treatment. After surface polishing, the flashover voltage of the epoxy sample becomes higher.
The factors on pulsed vacuum flashover of epoxy composite filled with micro-scale Al2O3·3H2O particles are studied. The effects of coupling agent, dispersion method, curing agent, and surface roughness on the flashover properties are investigated respectively. Compared with the amine curing agent, the casting epoxy resin cured by the acid anhydride has higher flashover voltage. The epoxy composite matrix dispersed by the high shear force has better disperse effect compared with that dispersed by the ultrasonic dispersion method. Epoxy composite filled with micro-scale particles treated by coupling agent has higher flashover voltage than that without coupling agent treatment. After surface polishing, the flashover voltage of the epoxy sample becomes higher.
2008,
20.
Abstract:
Target location accuracy is a key index for the microbeam irradiation. Therefore, a method for capturing and locating the microbeam position is offered. The microbeam position is identified by imaging the fluorescent spot excited when particles hit the scintillation foil. Using the image capture and analysis system, the fluorescent spot is analyzed to determine the microbeam position. Furthermore, experiments using CR39 nuclear track detector to measure the microbeam locating method are presented. The overall target location accuracy is measured when a borosilicate glass capillary with 5 μm inner diameter and 980 μm length is used as the microbeam collimator．
Target location accuracy is a key index for the microbeam irradiation. Therefore, a method for capturing and locating the microbeam position is offered. The microbeam position is identified by imaging the fluorescent spot excited when particles hit the scintillation foil. Using the image capture and analysis system, the fluorescent spot is analyzed to determine the microbeam position. Furthermore, experiments using CR39 nuclear track detector to measure the microbeam locating method are presented. The overall target location accuracy is measured when a borosilicate glass capillary with 5 μm inner diameter and 980 μm length is used as the microbeam collimator．
2008,
20.
Abstract:
In this paper, simulation with the Monte Carlo method is used to study the slot method and the knife-edge method. Results from different experiment layouts are compared. It is suggested that the high penetrability of X-ray has bad effect on the measured value of the spot size of the Ｘ-ray source. In order to reduce this effect, a new experiment layout is designed without impairing the image reception range, the contrast and the measuring precision. Simulation results from the show that more exact measured spot size of the Ｘ-ray source can be obtained with the new experiment layout.
In this paper, simulation with the Monte Carlo method is used to study the slot method and the knife-edge method. Results from different experiment layouts are compared. It is suggested that the high penetrability of X-ray has bad effect on the measured value of the spot size of the Ｘ-ray source. In order to reduce this effect, a new experiment layout is designed without impairing the image reception range, the contrast and the measuring precision. Simulation results from the show that more exact measured spot size of the Ｘ-ray source can be obtained with the new experiment layout.
2008,
20.
Abstract:
A model based on the multilayer lossy transmission line was set up for studying induction accelerator cavity with ferrite cores. Experiments in short pulse exciting in both 5 kV and 220 kV voltages and simulations by PSpice were used to prove the model, and the average permeability and permittivity of the core during the pulses were calculated. The experiment and simulation results show that the model can describe the dynamic physical characteristics of the induction cavity with ferrite cores accurately, and the model makes it easier and more efficient to ananlyze the waveforms, to optimize the device and to sclect the magnetic cores of the induction accelerator cavity.
A model based on the multilayer lossy transmission line was set up for studying induction accelerator cavity with ferrite cores. Experiments in short pulse exciting in both 5 kV and 220 kV voltages and simulations by PSpice were used to prove the model, and the average permeability and permittivity of the core during the pulses were calculated. The experiment and simulation results show that the model can describe the dynamic physical characteristics of the induction cavity with ferrite cores accurately, and the model makes it easier and more efficient to ananlyze the waveforms, to optimize the device and to sclect the magnetic cores of the induction accelerator cavity.
2008,
20.
Abstract:
The cooling design of a 201.25 MHz, 750 keV radio frequency quadrupole injector is described in this paper. The essential parameters for the design of the cooling pipes are obtained from the RF structure design. The hydrodynamics and thermal characteristics are theoretically analyzed. Computer simulation is performed using the steady state thermal analysis module of the radio-frequency software. Numerical computation shows that the increase of temperature is controlled within 1 K, the accelerator can work steadily with this cooling system. The cooling design satisfies the physical requirement very well．
The cooling design of a 201.25 MHz, 750 keV radio frequency quadrupole injector is described in this paper. The essential parameters for the design of the cooling pipes are obtained from the RF structure design. The hydrodynamics and thermal characteristics are theoretically analyzed. Computer simulation is performed using the steady state thermal analysis module of the radio-frequency software. Numerical computation shows that the increase of temperature is controlled within 1 K, the accelerator can work steadily with this cooling system. The cooling design satisfies the physical requirement very well．
2008,
20.
Abstract:
Pulse bump orbit technique can realize adjustable interval of Hefei light source HLS light pulse. In order to obtain high-current short pulse with high repeat frequency for the fast kicker, the experimental study based on the MOSFET solid modulator technique was carried out. The designed prototype has the structure of a 10-group MOSFET switch parallel and a 6 level inductive-adder, including fast trigger signal production, power drive circuit’s design, inductive-adder type configuration. The device obtains a pulse output of 100 ns width, 20 kHz repeat rate, 60 A summit current and 2 kV peak voltage．
Pulse bump orbit technique can realize adjustable interval of Hefei light source HLS light pulse. In order to obtain high-current short pulse with high repeat frequency for the fast kicker, the experimental study based on the MOSFET solid modulator technique was carried out. The designed prototype has the structure of a 10-group MOSFET switch parallel and a 6 level inductive-adder, including fast trigger signal production, power drive circuit’s design, inductive-adder type configuration. The device obtains a pulse output of 100 ns width, 20 kHz repeat rate, 60 A summit current and 2 kV peak voltage．
2008,
20.
Abstract:
Based on digital technology, using the up and down converter, IQ modulator and demodulator techniques, the magnitude control, frequency control and feedback phase control are realized and the low level RF system for Shanghai synchrotion radiation facility(SSRF) is designed. The beam current of SSRF is about 300 mA.In order to suppress the Robinson instability and the zero-mode beam instability, the RF feedback and zero-mode beam feedback will be added. How to design the up and down converter,IQ modulator and demodulator, clock distribution and phase locked techniques will be discussed in this paper. The results of the system testing at high power are given in this paper. The low level RF system has realized the design requirements: amplitude control accuracy rate of ± 1%, frequency contro
Based on digital technology, using the up and down converter, IQ modulator and demodulator techniques, the magnitude control, frequency control and feedback phase control are realized and the low level RF system for Shanghai synchrotion radiation facility(SSRF) is designed. The beam current of SSRF is about 300 mA.In order to suppress the Robinson instability and the zero-mode beam instability, the RF feedback and zero-mode beam feedback will be added. How to design the up and down converter,IQ modulator and demodulator, clock distribution and phase locked techniques will be discussed in this paper. The results of the system testing at high power are given in this paper. The low level RF system has realized the design requirements: amplitude control accuracy rate of ± 1%, frequency contro
2008,
20.
Abstract:
This paper presents the physical design，optimization，structure，fabrication，microwave test results and operation of the 499.654 MHz subharmonic buncher for Shanghai Synchrotron Radiation Facility LINAC. The structure optimization of the 499.654 MHz sub-harmonic buncher has been carried out with two-dimensional finite difference method software Superfish and three-dimensional finite element method software HFSS. The optimized buncher has been developed and tested. The measurement results of the buncher agree well with the design values.During the beam target optimization it works very steadily．
This paper presents the physical design，optimization，structure，fabrication，microwave test results and operation of the 499.654 MHz subharmonic buncher for Shanghai Synchrotron Radiation Facility LINAC. The structure optimization of the 499.654 MHz sub-harmonic buncher has been carried out with two-dimensional finite difference method software Superfish and three-dimensional finite element method software HFSS. The optimized buncher has been developed and tested. The measurement results of the buncher agree well with the design values.During the beam target optimization it works very steadily．
