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RSS2014 Vol. 26, No. 11
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2014,
26: 110101.
doi: 10.11884/HPLPB201426.110101
Abstract:
An experiment of phase locking of 32 fiber lasers is reported. A coherent array of 32 fiber lasers is built and a high-speed high-precision phase controller is designed based on field programmable gate array(FPGA). When the stochastic parallel gradient descent (SPGD) algorithm is implemented by the phase controller, the phases of the fiber lasers are locked and the output power of the combined laser is enhanced by a factor of about 26.
An experiment of phase locking of 32 fiber lasers is reported. A coherent array of 32 fiber lasers is built and a high-speed high-precision phase controller is designed based on field programmable gate array(FPGA). When the stochastic parallel gradient descent (SPGD) algorithm is implemented by the phase controller, the phases of the fiber lasers are locked and the output power of the combined laser is enhanced by a factor of about 26.
2014,
26: 111001.
doi: 10.11884/HPLPB201426.111001
Abstract:
Pumping fiber laser systems requires high brightness and high power fiber coupled diode laser module. In this paper, a method to get the high brightness and high power fiber coupled diode laser module is proposed, which is achieved by technologies of precision beam collimation and free space beam combining based on mini-bar diode laser chip. Experiment is carried out on linear polarization diode laser using the multimode fiber with 200 m core diameter and 0.22 numerical apertures. The laser output from fiber is 280 W, equalizing brightness of 5.87 MW/(cm2sr) and the wall plug efficiency is 45.0%. With polarization beam combining method, output power can reach 500 W and brightness will exceed 10 MW/(cm2sr). The experiment results show that this method can be used in developing high brightness fiber coupled diode laser module with multi-hundred watts class output power.
Pumping fiber laser systems requires high brightness and high power fiber coupled diode laser module. In this paper, a method to get the high brightness and high power fiber coupled diode laser module is proposed, which is achieved by technologies of precision beam collimation and free space beam combining based on mini-bar diode laser chip. Experiment is carried out on linear polarization diode laser using the multimode fiber with 200 m core diameter and 0.22 numerical apertures. The laser output from fiber is 280 W, equalizing brightness of 5.87 MW/(cm2sr) and the wall plug efficiency is 45.0%. With polarization beam combining method, output power can reach 500 W and brightness will exceed 10 MW/(cm2sr). The experiment results show that this method can be used in developing high brightness fiber coupled diode laser module with multi-hundred watts class output power.
2014,
26: 111002.
doi: 10.11884/HPLPB201426.111002
Abstract:
Using the empirical mode decomposition direct threshold (EMD-DT) and empirical mode decomposition interval threshold (EMD-IT) to de-noise lidar return signals, aiming to solve the problem of mode-mixing, a method of EMD switch interval threshold (EMD-SIT) is applied. Firstly, the signal is processed by the use of EMD. Then the decomposed intrinsic mode functions (IMF) with noise are removed by zero-crossing rate method. Finally ,by the use of the zero-crossing threshold, a switch interval threshold is obtained, which combines the EMD-IT and EMD-DT to de-noise the noise signals. The comparisons of different thresholds and the de-noise experiment of lidar shows that noise can be removed effectively by the proposed method, meantime the mode mixing is restrained. Compared with EMD-DT and EMD-IT methods, EMD-SIT method has more advantages Therefore ,the demonstrated method has a promising future.
Using the empirical mode decomposition direct threshold (EMD-DT) and empirical mode decomposition interval threshold (EMD-IT) to de-noise lidar return signals, aiming to solve the problem of mode-mixing, a method of EMD switch interval threshold (EMD-SIT) is applied. Firstly, the signal is processed by the use of EMD. Then the decomposed intrinsic mode functions (IMF) with noise are removed by zero-crossing rate method. Finally ,by the use of the zero-crossing threshold, a switch interval threshold is obtained, which combines the EMD-IT and EMD-DT to de-noise the noise signals. The comparisons of different thresholds and the de-noise experiment of lidar shows that noise can be removed effectively by the proposed method, meantime the mode mixing is restrained. Compared with EMD-DT and EMD-IT methods, EMD-SIT method has more advantages Therefore ,the demonstrated method has a promising future.
2014,
26: 111003.
doi: 10.11884/HPLPB201426.111003
Abstract:
The performance of supersonic diffuser downstream the cavity in chemical oxygen-iodine laser pressure recovery system can obviously influence the flow field quality in cavity, and its static pressure recover and total pressure loose performance can determine the pressure recovery system size downstream the diffuser. This paper uses the numerical simulation method to research the influence of supersonic diffuser design parameter such as diffuser angle and diffuser outline and back pressure and so on. The study shows that, the static pressure ratio was increased about 33% and the total pressure recover coefficient was increased to 0.484 by means of adding a constant section with wedges between the cavity and the supersonic diffuser. At the same time, the flow filed quality such as static pressure and Mach number distribution in cavity was obviously improved.
The performance of supersonic diffuser downstream the cavity in chemical oxygen-iodine laser pressure recovery system can obviously influence the flow field quality in cavity, and its static pressure recover and total pressure loose performance can determine the pressure recovery system size downstream the diffuser. This paper uses the numerical simulation method to research the influence of supersonic diffuser design parameter such as diffuser angle and diffuser outline and back pressure and so on. The study shows that, the static pressure ratio was increased about 33% and the total pressure recover coefficient was increased to 0.484 by means of adding a constant section with wedges between the cavity and the supersonic diffuser. At the same time, the flow filed quality such as static pressure and Mach number distribution in cavity was obviously improved.
2014,
26: 111004.
doi: 10.11884/HPLPB201426.111004
Abstract:
In order to confirm the feasibility of carbon fiber processing using lasers, the processing of carbon fiber blocks using femtosecond and continuous laser sources was researched. The morphologies of the processed region applying femtosecond and continuous laser sources were investigated. Compared with the processing using continuous laser, the optical processing of carbon fiber blocks using a femtosecond laser with pulse duration of 40fs is efficient and the processing quality is excellent with the edge of the processed region quite smooth. The threshold of processing using femtosecond pulses was deduced to be in the level of 1012 W/cm2 by investigating the radius of processed region with different laser power. The experimental results prove that the optical processing of carbon fiber blocks is feasible.
In order to confirm the feasibility of carbon fiber processing using lasers, the processing of carbon fiber blocks using femtosecond and continuous laser sources was researched. The morphologies of the processed region applying femtosecond and continuous laser sources were investigated. Compared with the processing using continuous laser, the optical processing of carbon fiber blocks using a femtosecond laser with pulse duration of 40fs is efficient and the processing quality is excellent with the edge of the processed region quite smooth. The threshold of processing using femtosecond pulses was deduced to be in the level of 1012 W/cm2 by investigating the radius of processed region with different laser power. The experimental results prove that the optical processing of carbon fiber blocks is feasible.
2014,
26: 111005.
doi: 10.11884/HPLPB201426.111005
Abstract:
In order to decrease the quantization effect caused by quantization process of digital devices, we propose a method to reduce the quantization error for phase measuring profilometry (PMP). The proposed method is suitable for the measurement of high precision and the surface has little change in bump. Each pixel of the calculated phase can be corrected according to neighborhood pixels. The experiment result shows that the standard deviation of phase quantization error decreases 41.38% after correction. The accuracy of phase measurement is improved.
In order to decrease the quantization effect caused by quantization process of digital devices, we propose a method to reduce the quantization error for phase measuring profilometry (PMP). The proposed method is suitable for the measurement of high precision and the surface has little change in bump. Each pixel of the calculated phase can be corrected according to neighborhood pixels. The experiment result shows that the standard deviation of phase quantization error decreases 41.38% after correction. The accuracy of phase measurement is improved.
2014,
26: 111006.
doi: 10.11884/HPLPB201426.111006
Abstract:
This article mainly analyzed the application of optical measuring instruments, stereomicroscope and CCD imaging system to the spot measurement of high-order Bessel beam. By taking the high-order Bessel beam which is generated when incoherent LED green light is passing through the spiral phase plate and axicon as an example, we simulated the cross-section intensity distribution at different distances along the axial direction, and it is compared to corresponding experimental parameters, such as maximum non-diffracting distance, central spot diameter etc. The experimental result shows that the measurement results of stereomicroscope and CCD imaging system are in good agreement, but there are different merits and demerits between these two instruments, and the measurement error of stereomicroscope will affect the accuracy of measurement results.
This article mainly analyzed the application of optical measuring instruments, stereomicroscope and CCD imaging system to the spot measurement of high-order Bessel beam. By taking the high-order Bessel beam which is generated when incoherent LED green light is passing through the spiral phase plate and axicon as an example, we simulated the cross-section intensity distribution at different distances along the axial direction, and it is compared to corresponding experimental parameters, such as maximum non-diffracting distance, central spot diameter etc. The experimental result shows that the measurement results of stereomicroscope and CCD imaging system are in good agreement, but there are different merits and demerits between these two instruments, and the measurement error of stereomicroscope will affect the accuracy of measurement results.
2014,
26: 111007.
doi: 10.11884/HPLPB201426.111007
Abstract:
In order to study the gain and thermal aberration properties of cryogenic Yb:YAG amplifier, a liquid nitrogen cooled Yb:YAG laser amplifier was built. Small signal gain for different pumping intensity and thermal aberration at room temperature and cryogenic temperature were measured. The results show that, with less pumping energy higher gain could be obtained at cryogenic temperature than at room temperature. At room temperature with pumping current 200 A and pumping duration 1200 s, the small signal gain is 1.59; at cryogenic temperature with pumping current 200 A and pumping duration 400 s, the small signal gain is 1.82. The optical to optical efficiency has increased observably. The effect of amplified spontaneous emission (ASE) is more evident at cryogenic temperature. Using short duration pumping can reduce the effect of ASE. The effect of thermal management was increased significantly at cryogenic temperature, and the laser amplifier can run at a higher average power.
In order to study the gain and thermal aberration properties of cryogenic Yb:YAG amplifier, a liquid nitrogen cooled Yb:YAG laser amplifier was built. Small signal gain for different pumping intensity and thermal aberration at room temperature and cryogenic temperature were measured. The results show that, with less pumping energy higher gain could be obtained at cryogenic temperature than at room temperature. At room temperature with pumping current 200 A and pumping duration 1200 s, the small signal gain is 1.59; at cryogenic temperature with pumping current 200 A and pumping duration 400 s, the small signal gain is 1.82. The optical to optical efficiency has increased observably. The effect of amplified spontaneous emission (ASE) is more evident at cryogenic temperature. Using short duration pumping can reduce the effect of ASE. The effect of thermal management was increased significantly at cryogenic temperature, and the laser amplifier can run at a higher average power.
2014,
26: 111008.
doi: 10.11884/HPLPB201426.111008
Abstract:
This paper presents a theoretical study of influence of In content on the InGaAsSb/GaSb quantum well structure. The accurate relationship between the band gap and the In content is given. The band offset as functions of the In content is calculated numerically. The results show that as the In content increase, the band gap of InGaAsSb decreases accordingly, but the amount of stress enhances, the band edge shift gets larger, and the band offset of InGaAsSb/GaSb reduces. Meanwhile, The peak wavelength of spontaneous emission spectra exhibits redshift and the gain decreases with the increase of the In content. This proves that it is feasible to adjust and control the band gap by altering the In content, which is useful for tailoring the material property and the photonics device design.
This paper presents a theoretical study of influence of In content on the InGaAsSb/GaSb quantum well structure. The accurate relationship between the band gap and the In content is given. The band offset as functions of the In content is calculated numerically. The results show that as the In content increase, the band gap of InGaAsSb decreases accordingly, but the amount of stress enhances, the band edge shift gets larger, and the band offset of InGaAsSb/GaSb reduces. Meanwhile, The peak wavelength of spontaneous emission spectra exhibits redshift and the gain decreases with the increase of the In content. This proves that it is feasible to adjust and control the band gap by altering the In content, which is useful for tailoring the material property and the photonics device design.
2014,
26: 111009.
doi: 10.11884/HPLPB201426.111009
Abstract:
A spatial classification method based on local Gabor binary patterns (LGBP) is proposed to improve the accuracy of hyperspectral camouflage targets image classification. The LGBP, a multiple scale algorithm, is employed to extract both local and global texture features of hyperspectral image (HSI). The extracted texture features have properties of gray scale invariance and rotation invariance. Each pixel is characterized by both spectral and spatial features. In this way, diversity of inter-class is enhanced. A multi-kernel support vector machine (SVM) is employed as the classifier to integrate spectral and spatial information for classification. Experiments are conducted to demonstrate the efficiency of the proposed method. The overall accuracy and Kappa coefficient of the classification reach 95.6% and 0.937 respectively. The proposed method is helpful to improve the accuracy and robustness of hyperspectral image classification.
A spatial classification method based on local Gabor binary patterns (LGBP) is proposed to improve the accuracy of hyperspectral camouflage targets image classification. The LGBP, a multiple scale algorithm, is employed to extract both local and global texture features of hyperspectral image (HSI). The extracted texture features have properties of gray scale invariance and rotation invariance. Each pixel is characterized by both spectral and spatial features. In this way, diversity of inter-class is enhanced. A multi-kernel support vector machine (SVM) is employed as the classifier to integrate spectral and spatial information for classification. Experiments are conducted to demonstrate the efficiency of the proposed method. The overall accuracy and Kappa coefficient of the classification reach 95.6% and 0.937 respectively. The proposed method is helpful to improve the accuracy and robustness of hyperspectral image classification.
2014,
26: 111010.
doi: 10.11884/HPLPB201426.111010
Abstract:
Based on the current cleanliness standards, the definition of cleanliness only considers the size and the density of contaminations, ignoring the effects of different particles in laser-induced damage threshold. This article puts forward the effective cleanliness method, which contains the information of different chemical components in contaminations. The effective cleanliness method bases on the mass-transporting equation, combining with the previous standards. The calculation considers the molecular-level difference of contaminants of various classes. The result of the calculation on chemicals of the most amounts in LIL matches the experiment, proving the validity of this method. The effective cleanliness method provides a brand new assessment standard of contamination control in large laser engineering.
Based on the current cleanliness standards, the definition of cleanliness only considers the size and the density of contaminations, ignoring the effects of different particles in laser-induced damage threshold. This article puts forward the effective cleanliness method, which contains the information of different chemical components in contaminations. The effective cleanliness method bases on the mass-transporting equation, combining with the previous standards. The calculation considers the molecular-level difference of contaminants of various classes. The result of the calculation on chemicals of the most amounts in LIL matches the experiment, proving the validity of this method. The effective cleanliness method provides a brand new assessment standard of contamination control in large laser engineering.
2014,
26: 111011.
doi: 10.11884/HPLPB201426.111011
Abstract:
A given kind of silica substrates, which low hydroxy group is contained by, was made (quantitative analysis) by the way of infrared differential spectroscopy. Some characteristic absorption peaks of methylene and methyl were measured as a measurement of organic compound. As many data before and after fine CO2 jet spray cleaning were obtained, some rules appeared statistically. Cleaning rate connects to the polluted degree. The higher the polluted degree is, the faster the cleaning rate is. Cleaning rate can also be reduced by the mixture of mineral and big particles. Furthermore, topography affects cleaning rate, too. All of them support the research method, and the process and results claim that for research and production process optimization, it is very important to find a way to insure the consistency of polluted degree on the surface before fine CO2 jet spray cleaning.
A given kind of silica substrates, which low hydroxy group is contained by, was made (quantitative analysis) by the way of infrared differential spectroscopy. Some characteristic absorption peaks of methylene and methyl were measured as a measurement of organic compound. As many data before and after fine CO2 jet spray cleaning were obtained, some rules appeared statistically. Cleaning rate connects to the polluted degree. The higher the polluted degree is, the faster the cleaning rate is. Cleaning rate can also be reduced by the mixture of mineral and big particles. Furthermore, topography affects cleaning rate, too. All of them support the research method, and the process and results claim that for research and production process optimization, it is very important to find a way to insure the consistency of polluted degree on the surface before fine CO2 jet spray cleaning.
2014,
26: 111012.
doi: 10.11884/HPLPB201426.111012
Abstract:
A three-dimensional digital image correlation technique (3D-DIC) combined with infrared temperature measurement system is presented to investigate the thin aluminium alloy plate irradiated by CW laser for full-field measurement, which can present real-time deformation and temperature results. The influence of incidence laser power is investigated, and the result shows that the deformation and temperature of the spot center increase linearly as the incidence laser power increases. The model result agrees well with the experiment result. The three-dimensional digital image correlation technique (3D-DIC) combined with infrared temperature measurement system is a kind of effective measuring method to the analysis and understanding of the failure mechanism.
A three-dimensional digital image correlation technique (3D-DIC) combined with infrared temperature measurement system is presented to investigate the thin aluminium alloy plate irradiated by CW laser for full-field measurement, which can present real-time deformation and temperature results. The influence of incidence laser power is investigated, and the result shows that the deformation and temperature of the spot center increase linearly as the incidence laser power increases. The model result agrees well with the experiment result. The three-dimensional digital image correlation technique (3D-DIC) combined with infrared temperature measurement system is a kind of effective measuring method to the analysis and understanding of the failure mechanism.
2014,
26: 112001.
doi: 10.11884/HPLPB201426.112001
Abstract:
Flux of X-ray produced from focussing laser radiation onto solid target was measured using a Ross filter system. The system consists of two identical X-ray detectors, appropriate filters mounted ahead of each detector. Ross filter method uses the advantages of the X-ray nuclide adjacent similar rejection, can filter out a narrow-band interference and remove high-energy part of the plane to get the Ti target K-shell X-ray radiation yield. Experiment result shows that k-shell emission of 4.5-4.9 keV prevails over continuum spectra (coincidence with result from crystal spectrometer). Characteristic emission increases with increased laser energy and a peak in conversion efficiency appears near 21015 W/cm2.
Flux of X-ray produced from focussing laser radiation onto solid target was measured using a Ross filter system. The system consists of two identical X-ray detectors, appropriate filters mounted ahead of each detector. Ross filter method uses the advantages of the X-ray nuclide adjacent similar rejection, can filter out a narrow-band interference and remove high-energy part of the plane to get the Ti target K-shell X-ray radiation yield. Experiment result shows that k-shell emission of 4.5-4.9 keV prevails over continuum spectra (coincidence with result from crystal spectrometer). Characteristic emission increases with increased laser energy and a peak in conversion efficiency appears near 21015 W/cm2.
2014,
26: 112002.
doi: 10.11884/HPLPB201426.112002
Abstract:
The rectangular diagnostic hole on the side of SiO2/CH/Au hohlraum was machined by electrical discharge machining technology, and the dielectric is kerosene which has high carbon content and the electrode material is red copper which has good electrical conductivity. The size of diagnostic hole is characterized by OLYMPUS STM6 measuring microscope. The results indicate that dimension precision of the diagnostic hole is less than 10 m, and dimension uniformity is less than 5 m. The components of the conducting layer are characterized by EDS spectrum. The results indicate that carbon, which is product of chemical reaction of kerosene and copper and comes from the electrode, is the key component of the assistant conducting layer.
The rectangular diagnostic hole on the side of SiO2/CH/Au hohlraum was machined by electrical discharge machining technology, and the dielectric is kerosene which has high carbon content and the electrode material is red copper which has good electrical conductivity. The size of diagnostic hole is characterized by OLYMPUS STM6 measuring microscope. The results indicate that dimension precision of the diagnostic hole is less than 10 m, and dimension uniformity is less than 5 m. The components of the conducting layer are characterized by EDS spectrum. The results indicate that carbon, which is product of chemical reaction of kerosene and copper and comes from the electrode, is the key component of the assistant conducting layer.
2014,
26: 112003.
doi: 10.11884/HPLPB201426.112003
Abstract:
Pendant-drop apparatus used for measuring the interfacial tension of fluorobenzene drop and water is discussed. The ethanol, 1-butanol and polyvinyl alcohol as surfactants are dissolved in water. The interfacial adsorption parameters in these systems are determined experimentally. In this paper, the interface of fluorobenzene drop and water is clear if fluorobenzene and water is saturated mutually in advance. It is shown that the relations between interfacial tension and concentration of surfactant can be described by Langmuir-Szyszkowski equation. The criterion of instability based on sternling and scriven theory can be applied to fluorobenzene drop and water system.
Pendant-drop apparatus used for measuring the interfacial tension of fluorobenzene drop and water is discussed. The ethanol, 1-butanol and polyvinyl alcohol as surfactants are dissolved in water. The interfacial adsorption parameters in these systems are determined experimentally. In this paper, the interface of fluorobenzene drop and water is clear if fluorobenzene and water is saturated mutually in advance. It is shown that the relations between interfacial tension and concentration of surfactant can be described by Langmuir-Szyszkowski equation. The criterion of instability based on sternling and scriven theory can be applied to fluorobenzene drop and water system.
2014,
26: 112004.
doi: 10.11884/HPLPB201426.112004
Abstract:
Aluminum mandrel was electrolyzed in 1 mol/L sodium hydroxide solution using the electrolytic corrosion device. The relationship between voltage and current was got by changing the voltage (4-28 V). The surface of aluminum was absolutely passivated when the voltage was higher than 28 V. Activation energy was obtained from data fitted by changing the electrolyte temperature (20-35 ℃). Images of surface passivation samples and non-passivated sample were got from SEM. Non-passivated and passivated samples were analyzed and characterized by XRD. The main component of surface passivation layer was bayerite. Surface reaction process and passivated mechanism were inferred from the main component of passivation product.
Aluminum mandrel was electrolyzed in 1 mol/L sodium hydroxide solution using the electrolytic corrosion device. The relationship between voltage and current was got by changing the voltage (4-28 V). The surface of aluminum was absolutely passivated when the voltage was higher than 28 V. Activation energy was obtained from data fitted by changing the electrolyte temperature (20-35 ℃). Images of surface passivation samples and non-passivated sample were got from SEM. Non-passivated and passivated samples were analyzed and characterized by XRD. The main component of surface passivation layer was bayerite. Surface reaction process and passivated mechanism were inferred from the main component of passivation product.
2014,
26: 112006.
doi: 10.11884/HPLPB201426.112006
Abstract:
A method was presented that a compound ion source of LiD was used to heat hot spot produced in ICF experiment. The interacting process between LiD ion and DT plasma was analysed and the heating parameter was calculated by Monte-Carlo method under ICF experimental condition of 500 g/cm3 in density and 100 m in diameter. The results show that the smallest incident energy is 4.65, 122.83 and 368.5 MeV, respectively, and the smallest electronic current is 1.15107 A, and the deposition time is 0.07 ps, 0.49 ps and 0.64 ps for electron, deuterium ion and lithium ion, deuterium ion and lithium ion, respectively. The largest deposition energy for deuterium ion in hotspot is 34.43 MeV. Compared to the methods in present particle beam projects, the compound ion source could be better for hot spot heat.
A method was presented that a compound ion source of LiD was used to heat hot spot produced in ICF experiment. The interacting process between LiD ion and DT plasma was analysed and the heating parameter was calculated by Monte-Carlo method under ICF experimental condition of 500 g/cm3 in density and 100 m in diameter. The results show that the smallest incident energy is 4.65, 122.83 and 368.5 MeV, respectively, and the smallest electronic current is 1.15107 A, and the deposition time is 0.07 ps, 0.49 ps and 0.64 ps for electron, deuterium ion and lithium ion, deuterium ion and lithium ion, respectively. The largest deposition energy for deuterium ion in hotspot is 34.43 MeV. Compared to the methods in present particle beam projects, the compound ion source could be better for hot spot heat.
2014,
26: 112007.
doi: 10.11884/HPLPB201426.112007
Abstract:
Suprathermal electron is an important factor influencing ignition in inertial confine fusion. Measuring results of hard X-ray spectrum could get suprathermal electron temperature and suprathermal electron quantities. This project mainly built a system to measure hard X-ray spectrum in energy region of 5 keV to 88 keV utilizing filter-fluorescer method. The system accurately calibrated its scintillators sensitivity with an uncertainty of less than 10%. System signal-to-noise ratio was increased by shielding the interference from system insides and environment of measurement. System output linearity was enhanced from 4 to 104 by replacing a photo-multiple-tube which could stand bigger current and changing the size of aperture or filters thickness. Finally, the system succeeded in measuring a precise hard X-ray spectrum of Au-plane target in SG-Ⅲ prototype.
Suprathermal electron is an important factor influencing ignition in inertial confine fusion. Measuring results of hard X-ray spectrum could get suprathermal electron temperature and suprathermal electron quantities. This project mainly built a system to measure hard X-ray spectrum in energy region of 5 keV to 88 keV utilizing filter-fluorescer method. The system accurately calibrated its scintillators sensitivity with an uncertainty of less than 10%. System signal-to-noise ratio was increased by shielding the interference from system insides and environment of measurement. System output linearity was enhanced from 4 to 104 by replacing a photo-multiple-tube which could stand bigger current and changing the size of aperture or filters thickness. Finally, the system succeeded in measuring a precise hard X-ray spectrum of Au-plane target in SG-Ⅲ prototype.
2014,
26: 112008.
doi: 10.11884/HPLPB201426.112008
Abstract:
This paper studied the effect of different annealing temperature on surface roughness, surface morphology and grain orientation of the mirror surface pure iron insulated for 60 min in vacuum. The results showed that the root mean square surface roughness increased slowly with increasing annealing temperature below the polymorphic transition temperature, and that root mean square surface roughness of mirror surface mutated from 4-5 nm to 700 nm in the polymorphic transformation temperature and above. Recrystallized fine grains were observed on the sample surface at 810 ℃ by scanning electron microscope (SEM). Research of XRD {200} crystal plane pole figures on the raw material and samples with several temperature points between 860-960 ℃ showed that preferential crystalline orientation had occurred at 860 ℃, and that the crystalline orientation is more and more obvious with the temperature increasing. The study found that the recrystallization has little effect on the surface roughness. Preferential crystalline orientation made different coefficient expansion in different directions, and the polymorphic transformation leads to volume changes causing uneven surface by the extrusion between crystal grains and the deeper grain boundaries, which is the main reason causing surface roughness mutation.
This paper studied the effect of different annealing temperature on surface roughness, surface morphology and grain orientation of the mirror surface pure iron insulated for 60 min in vacuum. The results showed that the root mean square surface roughness increased slowly with increasing annealing temperature below the polymorphic transition temperature, and that root mean square surface roughness of mirror surface mutated from 4-5 nm to 700 nm in the polymorphic transformation temperature and above. Recrystallized fine grains were observed on the sample surface at 810 ℃ by scanning electron microscope (SEM). Research of XRD {200} crystal plane pole figures on the raw material and samples with several temperature points between 860-960 ℃ showed that preferential crystalline orientation had occurred at 860 ℃, and that the crystalline orientation is more and more obvious with the temperature increasing. The study found that the recrystallization has little effect on the surface roughness. Preferential crystalline orientation made different coefficient expansion in different directions, and the polymorphic transformation leads to volume changes causing uneven surface by the extrusion between crystal grains and the deeper grain boundaries, which is the main reason causing surface roughness mutation.
2014,
26: 113001.
doi: 10.11884/HPLPB201426.113001
Abstract:
Electron optics system of W-band extended interaction klystron (EIK) which produces and transfers electron beam consists of Pierce electron gun and uniform permanent magnetic system. The Pierece electron gun is designed and optimized through Vaughan synthesis method and numerical simulation. What is more, the uniform permanent magnetic structure is developed according to transport character requirements of electron beam. Due to 3D program simulation of electron optics system for W-band EIK, parameters of gun are perveance of 0.21 P, current of more than 0.5 A, average waist radius of less than 0.3 mm and gunshot of more than 11 mm. In the permanent magnetic focusing system, magnetic field is about 0.33 T. Transmission distance of electron beam is more than 50 mm and transfer efficiency achieves 100%. The gun and focusing system are completely developed and product testing shows technical parameters satisfy the requirements. At present, the electron optics system for W-band EIK is in the state of installation and experiment.
Electron optics system of W-band extended interaction klystron (EIK) which produces and transfers electron beam consists of Pierce electron gun and uniform permanent magnetic system. The Pierece electron gun is designed and optimized through Vaughan synthesis method and numerical simulation. What is more, the uniform permanent magnetic structure is developed according to transport character requirements of electron beam. Due to 3D program simulation of electron optics system for W-band EIK, parameters of gun are perveance of 0.21 P, current of more than 0.5 A, average waist radius of less than 0.3 mm and gunshot of more than 11 mm. In the permanent magnetic focusing system, magnetic field is about 0.33 T. Transmission distance of electron beam is more than 50 mm and transfer efficiency achieves 100%. The gun and focusing system are completely developed and product testing shows technical parameters satisfy the requirements. At present, the electron optics system for W-band EIK is in the state of installation and experiment.
2014,
26: 113002.
doi: 10.11884/HPLPB201426.113002
Abstract:
In this article, the electron trajectory and thermal distribution in the collector region of W-band gyrotron traveling-wave tube were calculated with PIC code and thermal analysis code. Through the optimization of collector magnetic field parameters, the electron distribution in the collector region was simulated and the area of electron trajectory was increased from 17.05 cm2 to 28.52 cm2 (nearly 67% larger), which reduced the power density per unit area. Then the power density was determined to be 1 kW/cm2 and the rate of cooling water flow 1.12 L/s by the thermal analysis of thermal distribution in the collector, which makes the temperature of the inner wall of collector lower than the melting point of the material, us physical cracks will not occur, which could ensure the stability of the collector, so that the whole gyro-TWT could work steadily. Thermal analysis has verified the feasibility of optimal method, and the method has been used in practical tubes.
In this article, the electron trajectory and thermal distribution in the collector region of W-band gyrotron traveling-wave tube were calculated with PIC code and thermal analysis code. Through the optimization of collector magnetic field parameters, the electron distribution in the collector region was simulated and the area of electron trajectory was increased from 17.05 cm2 to 28.52 cm2 (nearly 67% larger), which reduced the power density per unit area. Then the power density was determined to be 1 kW/cm2 and the rate of cooling water flow 1.12 L/s by the thermal analysis of thermal distribution in the collector, which makes the temperature of the inner wall of collector lower than the melting point of the material, us physical cracks will not occur, which could ensure the stability of the collector, so that the whole gyro-TWT could work steadily. Thermal analysis has verified the feasibility of optimal method, and the method has been used in practical tubes.
2014,
26: 113003.
doi: 10.11884/HPLPB201426.113003
Abstract:
The sapphire window for 3 mm gyro-traveling wave tube(TWT) can not meet the design requirement of power capacity. To solve the problem, comparisons of several materials in power capacity and thermal shock resistance are carried out. A microwave plasma chemical vapor deposition(MPCVD) diamond window of low reflectivity and absorption for 3 mm high power gyro-TWT is designed by using numerical calculation and simulation. The results indicate that the designed MPCVD diamond window is appropriate for outputting TE01 mode, the bandwidth in which S11 is less than -20 dB is about 6 GHz. In addition, the thermal shock resistance of the window is good and the power capacity is about 61 kW in the condition of natural convection heat
The sapphire window for 3 mm gyro-traveling wave tube(TWT) can not meet the design requirement of power capacity. To solve the problem, comparisons of several materials in power capacity and thermal shock resistance are carried out. A microwave plasma chemical vapor deposition(MPCVD) diamond window of low reflectivity and absorption for 3 mm high power gyro-TWT is designed by using numerical calculation and simulation. The results indicate that the designed MPCVD diamond window is appropriate for outputting TE01 mode, the bandwidth in which S11 is less than -20 dB is about 6 GHz. In addition, the thermal shock resistance of the window is good and the power capacity is about 61 kW in the condition of natural convection heat
2014,
26: 113004.
doi: 10.11884/HPLPB201426.113004
Abstract:
In order to compensate for the nonlinear characteristics of different types of power amplifier, a Ka-band adjustable predistortion linearizer is presented. Based on three branches directional coupler, GaAs Schottky diodes, microstrip line and the load resistance, the linearizer can provide different nonlinear signals with changing the voltage bias of the two diodes, electrical length and characteristic impedance of the microstrip line. The simulation and measured results show that linearizer is able to form different kinds of predistortion signals. When the travelling wave tube amplifiers (TWTAs) are used, the linearizer can provide approximate 6.5 dB gain expansion and 46 phase expansion. When the solid state power amplifiers (SSPAs) are used, the linearizer can provide approximate 11 dB gain expansion and 35 phase compression.
In order to compensate for the nonlinear characteristics of different types of power amplifier, a Ka-band adjustable predistortion linearizer is presented. Based on three branches directional coupler, GaAs Schottky diodes, microstrip line and the load resistance, the linearizer can provide different nonlinear signals with changing the voltage bias of the two diodes, electrical length and characteristic impedance of the microstrip line. The simulation and measured results show that linearizer is able to form different kinds of predistortion signals. When the travelling wave tube amplifiers (TWTAs) are used, the linearizer can provide approximate 6.5 dB gain expansion and 46 phase expansion. When the solid state power amplifiers (SSPAs) are used, the linearizer can provide approximate 11 dB gain expansion and 35 phase compression.
2014,
26: 113005.
doi: 10.11884/HPLPB201426.113005
Abstract:
Based on analyzing the dispersion characteristics and the global band gaps for general two-dimensional photonic band gap structures formed by triangular arrays of metal posts, we select TE04 at 140 GHz as the operational mode and present the modes distribution diagram in different band gaps. By optimizing the operational point, the number of modes competing with TE04 reduces from 5 to 2. On the other hand, the lattice constant and the radius of metal columns are expanded, thus it can bear more thermal loading. Finally, comparisons are made between electric field distributions of TE04 in different band gaps.
Based on analyzing the dispersion characteristics and the global band gaps for general two-dimensional photonic band gap structures formed by triangular arrays of metal posts, we select TE04 at 140 GHz as the operational mode and present the modes distribution diagram in different band gaps. By optimizing the operational point, the number of modes competing with TE04 reduces from 5 to 2. On the other hand, the lattice constant and the radius of metal columns are expanded, thus it can bear more thermal loading. Finally, comparisons are made between electric field distributions of TE04 in different band gaps.
Statistical prediction of dielectric single-surface multipactor discharge in strong oblique DC Field
2014,
26: 113006.
doi: 10.11884/HPLPB201426.113006
Abstract:
The traditional method used for analyzing the multipactor of the dielectric is particle-in-cell method, but it has some shortcomings, such as time-consuming, large amount of computation and so on. The numerical simulation of multipactor in the dielectric surface breakdown in strong oblique DC field is realized by using statistical methods. The V-T graphs of the number of secondary electrons, average transit time and other key parameters are given. The influence of the smooth surface coefficient and the secondary electron yield coefficient of dielectric on the multipactor are investigated. The results show that the multipactor exists in the tilt angle area under strong oblique DC field, the multipactor may not occur while the tilt angle is too large or too small. If the tilt angle is located in susceptible area, the number of electrons in saturation will gain inversely with the inclination angle. Choosing the dielectric material with lower secondary electron yield coefficient, we can get a better inhibiting performance of multipactor.
The traditional method used for analyzing the multipactor of the dielectric is particle-in-cell method, but it has some shortcomings, such as time-consuming, large amount of computation and so on. The numerical simulation of multipactor in the dielectric surface breakdown in strong oblique DC field is realized by using statistical methods. The V-T graphs of the number of secondary electrons, average transit time and other key parameters are given. The influence of the smooth surface coefficient and the secondary electron yield coefficient of dielectric on the multipactor are investigated. The results show that the multipactor exists in the tilt angle area under strong oblique DC field, the multipactor may not occur while the tilt angle is too large or too small. If the tilt angle is located in susceptible area, the number of electrons in saturation will gain inversely with the inclination angle. Choosing the dielectric material with lower secondary electron yield coefficient, we can get a better inhibiting performance of multipactor.
2014,
26: 113007.
doi: 10.11884/HPLPB201426.113007
Abstract:
Cauchy method can only diagnose the bandpass filters without source-load coupling. To solve this problem, a method is proposed for diagnosing cross-coupled resonator bandstop and bandpass filters with source-load coupling. Firstly, an optimization method based on the genetic algorithm (GA) is proposed to determine source-load coupling coefficient, and to remove the phase-shift effects on the simulated S-parameters, which are caused by the transmission lines at the input/output ports of a filter. Secondly, the characteristic polynomials of the S-parameters can be solved in one step using the Cauchy method. Finally, the N+2 coupling matrix of a filter can be extracted from the characteristic polynomials and source-load coupling coefficient using well established techniques. The proposed method can reveal what is wrong with the filter and its tuning direction by comparing the difference between the ideal and the extracted coupling matrix. Therefore, the proposed method can guide the process of the filter tuning which can speed up the design and realization of a cross-coupled resonator bandstop and bandpass filter.
Cauchy method can only diagnose the bandpass filters without source-load coupling. To solve this problem, a method is proposed for diagnosing cross-coupled resonator bandstop and bandpass filters with source-load coupling. Firstly, an optimization method based on the genetic algorithm (GA) is proposed to determine source-load coupling coefficient, and to remove the phase-shift effects on the simulated S-parameters, which are caused by the transmission lines at the input/output ports of a filter. Secondly, the characteristic polynomials of the S-parameters can be solved in one step using the Cauchy method. Finally, the N+2 coupling matrix of a filter can be extracted from the characteristic polynomials and source-load coupling coefficient using well established techniques. The proposed method can reveal what is wrong with the filter and its tuning direction by comparing the difference between the ideal and the extracted coupling matrix. Therefore, the proposed method can guide the process of the filter tuning which can speed up the design and realization of a cross-coupled resonator bandstop and bandpass filter.
2014,
26: 113008.
doi: 10.11884/HPLPB201426.113008
Abstract:
The design of election beam collector for high-power microwave source driven by sheet electron beam is presented. Besides collecting electrons, the collector can effectively transform rectangular TM11 mode engendered by microwave source with sheet electron beam. The transmittal efficiency is higher than 95% when the frequency is in the range of 13 GHz to 27 GHz. The wide-band character can improve efficiency of the design and simulation of high-power microwave source with sheet beam. The transmittal efficiency of TM11 mode is not sensitive to the thickness and length of the collector. The heat dissipation of this collector performs well and it is able to hold the impact of electron beam with 3 kA, 300 kV, 30 ns pulse-width and 50 Hz repetitive operation, just cooled by natural air convection and heat radiation. The results are important to the design of high-power microwave generators driven by sheet electron beams.
The design of election beam collector for high-power microwave source driven by sheet electron beam is presented. Besides collecting electrons, the collector can effectively transform rectangular TM11 mode engendered by microwave source with sheet electron beam. The transmittal efficiency is higher than 95% when the frequency is in the range of 13 GHz to 27 GHz. The wide-band character can improve efficiency of the design and simulation of high-power microwave source with sheet beam. The transmittal efficiency of TM11 mode is not sensitive to the thickness and length of the collector. The heat dissipation of this collector performs well and it is able to hold the impact of electron beam with 3 kA, 300 kV, 30 ns pulse-width and 50 Hz repetitive operation, just cooled by natural air convection and heat radiation. The results are important to the design of high-power microwave generators driven by sheet electron beams.
2014,
26: 113009.
doi: 10.11884/HPLPB201426.113009
Abstract:
The S-band low temperature co-fired ceramics (LTCC) ferrite circulator was designed and analyzed based on multilayer chip structure, and the effect of some key problems in the preparing process on the frequency characteristic of the LTCC ferrite circulator was investigated by simulation method. The results show that the LTCC ferrite circulator with hybrid structure, which consists of microwave ferrite layer, ceramic dielectric layer and three-dimensional matching circuit, can provide excellent in-band performance. The cylindrical conductor connects two impedance lines in the three-dimensional wiring circuit of the LTCC ferrite circulator. It is found that the transmission and isolation characteristics of the LTCC ferrite circulator deteriorate rapidly, when the height of port air gap under cylindrical conductor reaches 20 m. In order to resist the significant reduction of the transmission and isolation characteristics, the air gap between microwave ferrite layer and ceramic dielectric layer should not be more than 20 m. Consequently, the matching co-firing between cylindrical conductor and ceramic dielectric layer, and between microwave ferrite layer and ceramic dielectric layer is extremely important to ensure excellent performance of the prepared LTCC ferrite circulator.
The S-band low temperature co-fired ceramics (LTCC) ferrite circulator was designed and analyzed based on multilayer chip structure, and the effect of some key problems in the preparing process on the frequency characteristic of the LTCC ferrite circulator was investigated by simulation method. The results show that the LTCC ferrite circulator with hybrid structure, which consists of microwave ferrite layer, ceramic dielectric layer and three-dimensional matching circuit, can provide excellent in-band performance. The cylindrical conductor connects two impedance lines in the three-dimensional wiring circuit of the LTCC ferrite circulator. It is found that the transmission and isolation characteristics of the LTCC ferrite circulator deteriorate rapidly, when the height of port air gap under cylindrical conductor reaches 20 m. In order to resist the significant reduction of the transmission and isolation characteristics, the air gap between microwave ferrite layer and ceramic dielectric layer should not be more than 20 m. Consequently, the matching co-firing between cylindrical conductor and ceramic dielectric layer, and between microwave ferrite layer and ceramic dielectric layer is extremely important to ensure excellent performance of the prepared LTCC ferrite circulator.
2014,
26: 113101.
doi: 10.11884/HPLPB201426.113101
Abstract:
As the extension of the microwave and millimeter-wave, the terahertz wave provides much greater communication bandwidth and capacity than millimeter wave. The THz pulses appeare the temporal and spatial deformation because of the waves scattered by the incident particles, and the pulses signal attenuation occurs. Based on the Mie theory, using the discrete distribution of particles with the random wave transmission and scattering theory, the extinction coefficient of fog droplet in the THz wave is calculated. Considering the fog particle spectral distribution, we obtain the average scattering characteristics with different incident wavelengths. The multiple scattering property of the THz signal from advection fog, e.g. the transmissivity and reflectivity, is investigated with Monte Carlo method. The forward and backward scattering intensities with the scattering angle by different visibility are analyzed. The result shows that in the atmospheric environment with a lower visibility, the absorption and attenuation caused by fog in terahertz wavelength can not be ignored. The research in the paper is of great significance to the space transmission and communication application of the terahertz technology.
As the extension of the microwave and millimeter-wave, the terahertz wave provides much greater communication bandwidth and capacity than millimeter wave. The THz pulses appeare the temporal and spatial deformation because of the waves scattered by the incident particles, and the pulses signal attenuation occurs. Based on the Mie theory, using the discrete distribution of particles with the random wave transmission and scattering theory, the extinction coefficient of fog droplet in the THz wave is calculated. Considering the fog particle spectral distribution, we obtain the average scattering characteristics with different incident wavelengths. The multiple scattering property of the THz signal from advection fog, e.g. the transmissivity and reflectivity, is investigated with Monte Carlo method. The forward and backward scattering intensities with the scattering angle by different visibility are analyzed. The result shows that in the atmospheric environment with a lower visibility, the absorption and attenuation caused by fog in terahertz wavelength can not be ignored. The research in the paper is of great significance to the space transmission and communication application of the terahertz technology.
2014,
26: 113201.
doi: 10.11884/HPLPB201426.113201
Abstract:
According to radars anti-deception-jamming, this paper studies an algorithm based on particle filter with the fact that the power of deception jamming is higher than target echo signal. When deception jamming appears, the importance weight values of particles in particle filter will get smaller, and we could detect the jamming and set the sampling point zero. In this way, the jamming will not match with the matched filter, and the jamming is restrained. In order to make the algorithm more practicable, this paper develops an improved particle filter that doesnt need to estimate state transition equation and measurement noise. Simulations are given to show that this approach can effectively restrain deception jamming and it is little affected by jamming to signal ratio.
According to radars anti-deception-jamming, this paper studies an algorithm based on particle filter with the fact that the power of deception jamming is higher than target echo signal. When deception jamming appears, the importance weight values of particles in particle filter will get smaller, and we could detect the jamming and set the sampling point zero. In this way, the jamming will not match with the matched filter, and the jamming is restrained. In order to make the algorithm more practicable, this paper develops an improved particle filter that doesnt need to estimate state transition equation and measurement noise. Simulations are given to show that this approach can effectively restrain deception jamming and it is little affected by jamming to signal ratio.
2014,
26: 114001.
doi: 10.11884/HPLPB201426.114001
Abstract:
Mass dispersion research of multi-mass plasma jet has important position in fields like separator or spectrometer. This paper studies the movement trajectory of multi-mass jet flow in inhomogeneous magnetic field and deduces an expression of mass dispersion. Considering the different incident angle and plume, we apply MATLAB to simulate motion trajectory of jet flow, calculate mass dispersion, and compare the result with mass dispersion in homogeneous magnetic field to confirm the effect of jet flow mass separation in this magnetic field. The simulation results show that the mass dispersion of multi-mass jet in inhomogeneous magnetic field is greater than that in homogeneous magnetic field, and that the mass separation of plasma jet can be efficiently realized.
Mass dispersion research of multi-mass plasma jet has important position in fields like separator or spectrometer. This paper studies the movement trajectory of multi-mass jet flow in inhomogeneous magnetic field and deduces an expression of mass dispersion. Considering the different incident angle and plume, we apply MATLAB to simulate motion trajectory of jet flow, calculate mass dispersion, and compare the result with mass dispersion in homogeneous magnetic field to confirm the effect of jet flow mass separation in this magnetic field. The simulation results show that the mass dispersion of multi-mass jet in inhomogeneous magnetic field is greater than that in homogeneous magnetic field, and that the mass separation of plasma jet can be efficiently realized.
2014,
26: 114002.
doi: 10.11884/HPLPB201426.114002
Abstract:
Jet Initiation Model is derived for light flash created by hypervelocity impact and experimental measurements for light flash phenomena of LY12 aluminum projectile hypervelocity impacting natural dolomite target were conducted at the conditions of near impact velocity and projectile incidence angles of 45 and 60 by using an optical pyrometer measurement system and a two-stage light gas gun loading system. Experimental results show that the peak value of the light flash intensity is bigger for projectile incidence angle of 45 than that for projectile incidence angle of 60 during LY12 aluminum projectile hypervelocity impacting natural dolomite plate, at the impacting velocity of 1.86 km/s and 1.96 km/s ,respectively.
Jet Initiation Model is derived for light flash created by hypervelocity impact and experimental measurements for light flash phenomena of LY12 aluminum projectile hypervelocity impacting natural dolomite target were conducted at the conditions of near impact velocity and projectile incidence angles of 45 and 60 by using an optical pyrometer measurement system and a two-stage light gas gun loading system. Experimental results show that the peak value of the light flash intensity is bigger for projectile incidence angle of 45 than that for projectile incidence angle of 60 during LY12 aluminum projectile hypervelocity impacting natural dolomite plate, at the impacting velocity of 1.86 km/s and 1.96 km/s ,respectively.
2014,
26: 114003.
doi: 10.11884/HPLPB201426.114003
Abstract:
Aimed at the problem of energy resolution on the research of neutron energy spectra experiments, based on the detecting systems relation between gamma ray and neutron, plus its gamma ray energy resolution, a practical and convenient numerical scheme is introduced. Using the gamma ray energy resolution and the light response relation of neutron and gamma ray of the detecting system, the neutron energy resolution of the system was obtained. Furthermore, the neutron resolution was applied in the numerical simulation of neutron energy spectra, and data comparison between numerical calculation and related experiments was processed. The results proved that the method can be commendably applied to the theoretical simulation of neutron energy spectra.
Aimed at the problem of energy resolution on the research of neutron energy spectra experiments, based on the detecting systems relation between gamma ray and neutron, plus its gamma ray energy resolution, a practical and convenient numerical scheme is introduced. Using the gamma ray energy resolution and the light response relation of neutron and gamma ray of the detecting system, the neutron energy resolution of the system was obtained. Furthermore, the neutron resolution was applied in the numerical simulation of neutron energy spectra, and data comparison between numerical calculation and related experiments was processed. The results proved that the method can be commendably applied to the theoretical simulation of neutron energy spectra.
2014,
26: 114004.
doi: 10.11884/HPLPB201426.114004
Abstract:
Most of the existing mesh simplification algorithms ignore some small features of the original model reconstructed by industrial CT serial images and the triangular meshes quality of the simplified model is poor. To solve this problem, a simplification method with feature preserving for mesh model was proposed. In this method, the original model was simplified by triangle collapse, and then after the average dihedral angle error of mesh model reached the allowable error, the model was simplified by edge collapse. For triangle collapse, the folding point of one triangle was determined by its normal vector, the Gaussian curvature of each vertex and vertices projection method. The collapsing cost of one triangle was determined by the sum of dimensionless number of its local volume error and its dihedral angle error. For edge collapse, the dihedral angle error was introduced in the edge collapse cost of QEM. The experiment result shows that the presented simplification method could generate the feature preserving, high quality and lower geometric error simplified model compared with most of the existing simplification algorithms.
Most of the existing mesh simplification algorithms ignore some small features of the original model reconstructed by industrial CT serial images and the triangular meshes quality of the simplified model is poor. To solve this problem, a simplification method with feature preserving for mesh model was proposed. In this method, the original model was simplified by triangle collapse, and then after the average dihedral angle error of mesh model reached the allowable error, the model was simplified by edge collapse. For triangle collapse, the folding point of one triangle was determined by its normal vector, the Gaussian curvature of each vertex and vertices projection method. The collapsing cost of one triangle was determined by the sum of dimensionless number of its local volume error and its dihedral angle error. For edge collapse, the dihedral angle error was introduced in the edge collapse cost of QEM. The experiment result shows that the presented simplification method could generate the feature preserving, high quality and lower geometric error simplified model compared with most of the existing simplification algorithms.
2014,
26: 114005.
doi: 10.11884/HPLPB201426.114005
Abstract:
The semiconductors refractive indexes change when they are exposed to radiation pulses. For short carrier lifetime, some semiconductors refractive indexes recover quickly. This process can be used to develop a new kind of pulse radiation detector. An interferometer was established to sense the change of refractive index of 300 um GaAs plate. The probe beam was provided by infrared (1310 nm) single mode continuous wave laser. The infrared beam illuminated GaAs with a certain angle. Two main branches of this beam interfered along the reflected path. One branch was reflected from front cover of GaAs. The other branch was the light refracted into GaAs and reflected back from the back cover of GaAs and then refracted out of GaAs. The interference light intensity changed with the change of refractive index of GaAs. The pump source was pulse radiation, 300 keV, 20 ns. The interfered light intensity was recorded by InGaAs infrared 775 kHz detector. Change of refractive index caused by the pulse radiation was detected. The nonequilibrium free carrier density and the change of refractive index were computed about 1014 cm-3 and 10-6, respectively. The experiment results were approximately consistent with the computed results, which suggests that the index modulation technology can be used for pulse radiation detection.
The semiconductors refractive indexes change when they are exposed to radiation pulses. For short carrier lifetime, some semiconductors refractive indexes recover quickly. This process can be used to develop a new kind of pulse radiation detector. An interferometer was established to sense the change of refractive index of 300 um GaAs plate. The probe beam was provided by infrared (1310 nm) single mode continuous wave laser. The infrared beam illuminated GaAs with a certain angle. Two main branches of this beam interfered along the reflected path. One branch was reflected from front cover of GaAs. The other branch was the light refracted into GaAs and reflected back from the back cover of GaAs and then refracted out of GaAs. The interference light intensity changed with the change of refractive index of GaAs. The pump source was pulse radiation, 300 keV, 20 ns. The interfered light intensity was recorded by InGaAs infrared 775 kHz detector. Change of refractive index caused by the pulse radiation was detected. The nonequilibrium free carrier density and the change of refractive index were computed about 1014 cm-3 and 10-6, respectively. The experiment results were approximately consistent with the computed results, which suggests that the index modulation technology can be used for pulse radiation detection.
2014,
26: 114006.
doi: 10.11884/HPLPB201426.114006
Abstract:
In the extraction process of neutral beam ion source, the production of extraction current and deceleration current is analyzed and it is helpful for obtaining reliable extraction power and heat deposition power on the grids surface. Based on the electric connection way of the extraction grids of neutral beam ion source on HL-2A and the basic physical process during ion beam extraction, beam extraction process is analyzed and the principle sources of deceleration current are given. Through analyzing the results in gas pressure scanning experiment, it is found that with gas pressure increasing, deceleration current increases, and the ratio of deceleration current to extraction current increases approximately linearly. A physical model is set up based on the process of extracted ion beam coming through the extraction grids. The dependence of the ratio of deceleration current to the acceleration current on the discharge gas pressure is calculated, and the result is consistent with the experimental result which shows the rationality of the analysis method.
In the extraction process of neutral beam ion source, the production of extraction current and deceleration current is analyzed and it is helpful for obtaining reliable extraction power and heat deposition power on the grids surface. Based on the electric connection way of the extraction grids of neutral beam ion source on HL-2A and the basic physical process during ion beam extraction, beam extraction process is analyzed and the principle sources of deceleration current are given. Through analyzing the results in gas pressure scanning experiment, it is found that with gas pressure increasing, deceleration current increases, and the ratio of deceleration current to extraction current increases approximately linearly. A physical model is set up based on the process of extracted ion beam coming through the extraction grids. The dependence of the ratio of deceleration current to the acceleration current on the discharge gas pressure is calculated, and the result is consistent with the experimental result which shows the rationality of the analysis method.
2014,
26: 114007.
doi: 10.11884/HPLPB201426.114007
Abstract:
We designed the radiography imaging system based on the high energy electron beam using theoretical analysis and numerical simulation, and optimized the parameters using Geant4 and GPT software. In the simulation we analyzed the parameters which affect the system space resolution and areal density resolution. With the ability to resolve the thickness of the sample, the result shows that the method can reach space resolution of m. It proves that the design satisfies the demand to image the sample of certain thickness and structure.
We designed the radiography imaging system based on the high energy electron beam using theoretical analysis and numerical simulation, and optimized the parameters using Geant4 and GPT software. In the simulation we analyzed the parameters which affect the system space resolution and areal density resolution. With the ability to resolve the thickness of the sample, the result shows that the method can reach space resolution of m. It proves that the design satisfies the demand to image the sample of certain thickness and structure.
2014,
26: 114101.
doi: 10.11884/HPLPB201426.114101
Abstract:
The morphologies of silicon surfaces are modified with the single Nd:YAG nanosecond laser pulse (wavelength 532 nm) in air. The influence of single pulse laser energy density and spot size on the morphology is studied. The field emission scanning electron microscope (FESEM) and the atomic force microscope (AFM) measurement results show the formation of completely different morphologies in different conditions, and the thermodynamic process of nanosecond laser irradiating silicon is analyzed. We find that when the energy density is close to the melting threshold of silicon, and the spot size is as small as 8 m, the spike structures are fabricated. While increasing the energy density and the spot size, the conical spike structures gradually disappear, and the profile of the irradiated surface shows swellings and craters. We obtain approximate analytical solutions for the morphology by the hydrodynamic model, and the theoretical data show good agreement with AFM data for microstructures. The reason of the microstructure formation is that surface tension force drives the molten silicon to flow. The surface tension depends on the surface temperature gradient and the surfactant concentration. With the total effects of thermocapillary by the surface temperature gradient and surfactant compositional capillarity, the spike, swelling and craters can be fabricated.
The morphologies of silicon surfaces are modified with the single Nd:YAG nanosecond laser pulse (wavelength 532 nm) in air. The influence of single pulse laser energy density and spot size on the morphology is studied. The field emission scanning electron microscope (FESEM) and the atomic force microscope (AFM) measurement results show the formation of completely different morphologies in different conditions, and the thermodynamic process of nanosecond laser irradiating silicon is analyzed. We find that when the energy density is close to the melting threshold of silicon, and the spot size is as small as 8 m, the spike structures are fabricated. While increasing the energy density and the spot size, the conical spike structures gradually disappear, and the profile of the irradiated surface shows swellings and craters. We obtain approximate analytical solutions for the morphology by the hydrodynamic model, and the theoretical data show good agreement with AFM data for microstructures. The reason of the microstructure formation is that surface tension force drives the molten silicon to flow. The surface tension depends on the surface temperature gradient and the surfactant concentration. With the total effects of thermocapillary by the surface temperature gradient and surfactant compositional capillarity, the spike, swelling and craters can be fabricated.
2014,
26: 114102.
doi: 10.11884/HPLPB201426.114102
Abstract:
In this paper, graphene is synthesized from natural graphite by a modified Hummers method and glucose is added as reducing agent. Hydrothermal method is used to prepare MnO2/graphene composite using KMnO4 and HCl as raw materials. The structure is characterized by SEM and XRD. The result shows that MnO2 prepared by hydrothermal method is pure -MnO2, and the addition of graphene powder doesnt influence its crystal structure. Electrochemical characterization is performed using cyclic voltammetry and chronopotentiometry in 1 mol/L Na2SO4 aqueous solution electrolyte. The electrode has a stable electrochemistry performance, and preferable reversibility, the specific capacitance of MnO2/graphene electrode is 147.9 F/g under 1.27 mA/cm2 current densities. The electrode presents a stable capacitiance after 1000 cycles and it is an ideal electrochemical material.
In this paper, graphene is synthesized from natural graphite by a modified Hummers method and glucose is added as reducing agent. Hydrothermal method is used to prepare MnO2/graphene composite using KMnO4 and HCl as raw materials. The structure is characterized by SEM and XRD. The result shows that MnO2 prepared by hydrothermal method is pure -MnO2, and the addition of graphene powder doesnt influence its crystal structure. Electrochemical characterization is performed using cyclic voltammetry and chronopotentiometry in 1 mol/L Na2SO4 aqueous solution electrolyte. The electrode has a stable electrochemistry performance, and preferable reversibility, the specific capacitance of MnO2/graphene electrode is 147.9 F/g under 1.27 mA/cm2 current densities. The electrode presents a stable capacitiance after 1000 cycles and it is an ideal electrochemical material.
2014,
26: 114103.
doi: 10.11884/HPLPB201426.114103
Abstract:
To obtain the number and sizes of aerosols generated in the enclosed room of high power laser system, a method of microparticle detection with microfiber was demonstrated in enclosed room. The additional loss of microfiber, caused by adhered microparticles with different refractive indices and diameters, were researched and simulated based on the evanescent field theory. Microfibers were fabricated using hydrogen-oxygen flame-heated scanning fiber drawing method and placed in the high power laser facility for demonstration. The experimental results show that, 1 m- and 2 m-diameter contamination particles were detected by 1.5 m-diameter microfiber. The diameter and the number of microparticle can be estimated by measuring the additional loss of the sensing unit. The relation between the additional loss and space environment cleanliness can be obtained. The simulated results agree well with the experimental results.
To obtain the number and sizes of aerosols generated in the enclosed room of high power laser system, a method of microparticle detection with microfiber was demonstrated in enclosed room. The additional loss of microfiber, caused by adhered microparticles with different refractive indices and diameters, were researched and simulated based on the evanescent field theory. Microfibers were fabricated using hydrogen-oxygen flame-heated scanning fiber drawing method and placed in the high power laser facility for demonstration. The experimental results show that, 1 m- and 2 m-diameter contamination particles were detected by 1.5 m-diameter microfiber. The diameter and the number of microparticle can be estimated by measuring the additional loss of the sensing unit. The relation between the additional loss and space environment cleanliness can be obtained. The simulated results agree well with the experimental results.
2014,
26: 115001.
doi: 10.11884/HPLPB201426.115001
Abstract:
Based on the principle of electromagnetic railgun launch, a circuit model was developed and validated, the pulse forming units (PFU) and the progress of the railgun launch were included. The corresponding Pspice circuit code was developed to simulate the current of each pulse forming unit. Acceleration properties of the armature were also simulated by the Pspice analog behavioral modeling tools. The simulated railgun current and the armature velocity were 2.6% and 9.8% higher than the experiment results, i.e., the simulation and the experiment results were roughly consistent with each other. The model has provided valuable data which can directly benefit the design and operation of the series augmented railgun systems.
Based on the principle of electromagnetic railgun launch, a circuit model was developed and validated, the pulse forming units (PFU) and the progress of the railgun launch were included. The corresponding Pspice circuit code was developed to simulate the current of each pulse forming unit. Acceleration properties of the armature were also simulated by the Pspice analog behavioral modeling tools. The simulated railgun current and the armature velocity were 2.6% and 9.8% higher than the experiment results, i.e., the simulation and the experiment results were roughly consistent with each other. The model has provided valuable data which can directly benefit the design and operation of the series augmented railgun systems.
2014,
26: 115002.
doi: 10.11884/HPLPB201426.115002
Abstract:
Based on solid heat conduction theory and multi-physics field coupling theory, the calculation equation of the armature surface transient wear is deduced, and the calculation method of contact resistance and the transient contact force is proposed. On this basis, armature transient wear calculation method is summarized and presented. The armature transient wear is analyzed with this method, when the contact length and width are changed. Pivot rail contact surface of wear is mainly distributed in the front edge and on both sides of the edge. Along the length direction of the contact, the wear is more and more light; along the contact width direction, the wear quantity increases firstly and then decreases; the middle part wear is light. Finally, armature surface wear rate calculation results are compared with the experimental results of IAT and they are in good agreement. This lays a foundation to establish relationship between armature wear and the transition theory.
Based on solid heat conduction theory and multi-physics field coupling theory, the calculation equation of the armature surface transient wear is deduced, and the calculation method of contact resistance and the transient contact force is proposed. On this basis, armature transient wear calculation method is summarized and presented. The armature transient wear is analyzed with this method, when the contact length and width are changed. Pivot rail contact surface of wear is mainly distributed in the front edge and on both sides of the edge. Along the length direction of the contact, the wear is more and more light; along the contact width direction, the wear quantity increases firstly and then decreases; the middle part wear is light. Finally, armature surface wear rate calculation results are compared with the experimental results of IAT and they are in good agreement. This lays a foundation to establish relationship between armature wear and the transition theory.
2014,
26: 115003.
doi: 10.11884/HPLPB201426.115003
Abstract:
Sliding interface status during whole electromagnetic rail launch process depends on contact status after initial assembly in which initial contact force between armature and rails(A-R) is provided by trailing arm elastic deformation in the C-armature rail launcher, which influences launcher system efficiency and rail lifespan. This paper focuses on the contact status of initial C-armature assembly of rail launcher with constructing the contact model for simulating computation and designing many groups of experiments for contrast testing. Considering safe deformable limits of armature material, variation laws of contact pressure, contact region(area) and contact force are analyzed under conditions of small-range feasible heads and tail sizes. Interferential proportion is proposed as a contact status dependent key parameter. Contact region transformed from tail to head of trailing arm as interferential proportion increasing, maximum of contact area is about half of whole outer surface of trailing arm. Optimal contact status for favorable electric contact and engineering implement technique are also discussed.
Sliding interface status during whole electromagnetic rail launch process depends on contact status after initial assembly in which initial contact force between armature and rails(A-R) is provided by trailing arm elastic deformation in the C-armature rail launcher, which influences launcher system efficiency and rail lifespan. This paper focuses on the contact status of initial C-armature assembly of rail launcher with constructing the contact model for simulating computation and designing many groups of experiments for contrast testing. Considering safe deformable limits of armature material, variation laws of contact pressure, contact region(area) and contact force are analyzed under conditions of small-range feasible heads and tail sizes. Interferential proportion is proposed as a contact status dependent key parameter. Contact region transformed from tail to head of trailing arm as interferential proportion increasing, maximum of contact area is about half of whole outer surface of trailing arm. Optimal contact status for favorable electric contact and engineering implement technique are also discussed.
2014,
26: 115004.
doi: 10.11884/HPLPB201426.115004
Abstract:
To improve the fuze-warhead coordination efficiency, the working principle of gun-launched electron-magnetic pulse bomb was analyzed, and the coordination process in actual ballistics was divided into two stages. Stage 1: the killing area model was built to analyze the optimum burst point, and by introducing damage parameters, this stages coordination efficiency was characterized by damage rate. Stage 2: the best initiation timing model was built, the timing error spreading was calculated using small deviation method, and the coordination efficiency was characterized by the degree of seed current closer to its maximum. Based on the analysis above, the calculation model of coordination efficiency was summarized, and some technical methods were given.
To improve the fuze-warhead coordination efficiency, the working principle of gun-launched electron-magnetic pulse bomb was analyzed, and the coordination process in actual ballistics was divided into two stages. Stage 1: the killing area model was built to analyze the optimum burst point, and by introducing damage parameters, this stages coordination efficiency was characterized by damage rate. Stage 2: the best initiation timing model was built, the timing error spreading was calculated using small deviation method, and the coordination efficiency was characterized by the degree of seed current closer to its maximum. Based on the analysis above, the calculation model of coordination efficiency was summarized, and some technical methods were given.
2014,
26: 115005.
doi: 10.11884/HPLPB201426.115005
Abstract:
For fast estimating the time-domain near-fields of flat-plate bounded wave electromagnetic pulse(EMP) simulator with vertical polarization, scattering transfer function method is used in time-domain simulation of this kind of simulator. A Gaussian pulse, whose effective frequency domain is wider than that of a given pulse source, is found firstly. And the time-domain response of electric fields at some testing points in the simulator excited by the Gaussian pulse source can be got by finite-difference time-domain (FDTD) method. Then the transient response of electric field at each testing point as the simulator excited by the given pulse source can be computed by Fourier transform, system transfer function and inverse Fourier transform. The results are well consistent with those got by FDTD method as the simulator is excited by the given pulse source directly. The method in this paper is useful for fast estimating radiation near-fields of a fixed simulator with different exciting sources. It has the advantages of reducing FDTD simulation time, saving much computing time and CPU storage especially for medium or large simulators.
For fast estimating the time-domain near-fields of flat-plate bounded wave electromagnetic pulse(EMP) simulator with vertical polarization, scattering transfer function method is used in time-domain simulation of this kind of simulator. A Gaussian pulse, whose effective frequency domain is wider than that of a given pulse source, is found firstly. And the time-domain response of electric fields at some testing points in the simulator excited by the Gaussian pulse source can be got by finite-difference time-domain (FDTD) method. Then the transient response of electric field at each testing point as the simulator excited by the given pulse source can be computed by Fourier transform, system transfer function and inverse Fourier transform. The results are well consistent with those got by FDTD method as the simulator is excited by the given pulse source directly. The method in this paper is useful for fast estimating radiation near-fields of a fixed simulator with different exciting sources. It has the advantages of reducing FDTD simulation time, saving much computing time and CPU storage especially for medium or large simulators.
2014,
26: 115006.
doi: 10.11884/HPLPB201426.115006
Abstract:
A nonlinear transmission line-based pulse-sharpening system with output pulse of high voltage into 50 for repetitive operation is developed. This paper describes the theory and design procedures of ferrite-loaded transmission line which is used to produce sub-nanosecond rise time electrical pulse with high power. The design parameters based on ferrite-loaded line are presented. In experiment, different factors on the fact of sharpening are analyzed. The experiment results show the pulse sharpening effect varies with different ferrite materials. It helps the final selecting of the most efficient ferrite material, the ferrite with higher saturation magnetization. The experiment results indicate that the axial bias is very important for the pulse sharpening. There is a best value of the axial bias for the fastest front of pulse. After optimization, an output pulse of 450 ps, 39 kV is obtained at load for high repetitive operation.
A nonlinear transmission line-based pulse-sharpening system with output pulse of high voltage into 50 for repetitive operation is developed. This paper describes the theory and design procedures of ferrite-loaded transmission line which is used to produce sub-nanosecond rise time electrical pulse with high power. The design parameters based on ferrite-loaded line are presented. In experiment, different factors on the fact of sharpening are analyzed. The experiment results show the pulse sharpening effect varies with different ferrite materials. It helps the final selecting of the most efficient ferrite material, the ferrite with higher saturation magnetization. The experiment results indicate that the axial bias is very important for the pulse sharpening. There is a best value of the axial bias for the fastest front of pulse. After optimization, an output pulse of 450 ps, 39 kV is obtained at load for high repetitive operation.
2014,
26: 115007.
doi: 10.11884/HPLPB201426.115007
Abstract:
A coaxial Blumlein line with a spiral inner and a spiral outer cylinders is proposed in this paper. The pulse forming process for this line is analyzed via the transmission theory of transverse electromagnetic wave. It is found that the electromagnetic wave can transmit independently in the inner line and in the outer line which is the same as that for the conventional Blumlein line. The analytical expression for the parameters such as the wave impedance and the slow-wave coefficient are presented. The proof-of-principle experiments are also conducted, which show that the top of the output pulse is flat and is about 80% of the full width at half maximum (FWHM). The experiments also show that the amplitude and the FWHM of the output pulse are in line with the theoretical values, which verifies the feasibility to produce long pulse with this type of line. The weakness of this type of line is that it tends to be affected by the peripheral environmental conductors. When the distance between the peripheral environmental conductors and the Blumlein line gets longer, this unfavorable effect is weaker. By placing a ferrite core between the bottom of the spiral outer cylinder and the ground flat conductor, the distance between them can be decreased from 500 mm to 100 mm.
A coaxial Blumlein line with a spiral inner and a spiral outer cylinders is proposed in this paper. The pulse forming process for this line is analyzed via the transmission theory of transverse electromagnetic wave. It is found that the electromagnetic wave can transmit independently in the inner line and in the outer line which is the same as that for the conventional Blumlein line. The analytical expression for the parameters such as the wave impedance and the slow-wave coefficient are presented. The proof-of-principle experiments are also conducted, which show that the top of the output pulse is flat and is about 80% of the full width at half maximum (FWHM). The experiments also show that the amplitude and the FWHM of the output pulse are in line with the theoretical values, which verifies the feasibility to produce long pulse with this type of line. The weakness of this type of line is that it tends to be affected by the peripheral environmental conductors. When the distance between the peripheral environmental conductors and the Blumlein line gets longer, this unfavorable effect is weaker. By placing a ferrite core between the bottom of the spiral outer cylinder and the ground flat conductor, the distance between them can be decreased from 500 mm to 100 mm.
2014,
26: 115008.
doi: 10.11884/HPLPB201426.115008
Abstract:
Muzzle velocity and system efficiency are two of the most important characteristics for synchronous induction coil electromagnetic launchers (SICEMLs), which could be affected by the structural parameters of the driving coil and the armature, the number of coil turns, and the initial position of the armature. To obtain the optimal parameters, genetic algorithm was introduced into the design process of a single stage SICEML in this paper. The optimization was derived based on the performance index defined as the product of the muzzle velocity and the system efficiency and the results were validated through the simulation by the finite element software Ansoft. The research results show that the system performance has improved effectively under the same storage power supply and total volume of the launcher: the system efficiency was increased from 5.38% to 13.6% and the muzzle velocity was increased from 38 m/s to 61 m/s. A single SICEML prototype was tested in blocked state and the test results show a good agreement with the simulation.
Muzzle velocity and system efficiency are two of the most important characteristics for synchronous induction coil electromagnetic launchers (SICEMLs), which could be affected by the structural parameters of the driving coil and the armature, the number of coil turns, and the initial position of the armature. To obtain the optimal parameters, genetic algorithm was introduced into the design process of a single stage SICEML in this paper. The optimization was derived based on the performance index defined as the product of the muzzle velocity and the system efficiency and the results were validated through the simulation by the finite element software Ansoft. The research results show that the system performance has improved effectively under the same storage power supply and total volume of the launcher: the system efficiency was increased from 5.38% to 13.6% and the muzzle velocity was increased from 38 m/s to 61 m/s. A single SICEML prototype was tested in blocked state and the test results show a good agreement with the simulation.
2014,
26: 115009.
doi: 10.11884/HPLPB201426.115009
Abstract:
Plasma-filled rod-pinch diode (PFRPD) is a rod-pinch diode (RPD) filled with plasma that injected across the anode-cathode gap using plasma guns prior to the start of diode current. The injected plasma may reduce the impedance of PFRPD and enhance the dose rate of X-rays. A PIC simulating model of PFRPD is established. The beam pinching situation is described by the axial distribution of electron deposition density (ADEDD) on the anode rod. A PFRPD experiment platform is established, where a 1 MV PFRPD is driven by Jianguang-Ⅰ accelerator low impedance state(1 MV/9 /40 ns). Experiment results indicate that the diode performs better prefilled with appropriate plasma. The diode impedance is reduced to 10 , X ray radiation dose is increased from 0.76 mGy to 3.19 mGy, axial spot is reduced from 9 mm to 4 mm.
Plasma-filled rod-pinch diode (PFRPD) is a rod-pinch diode (RPD) filled with plasma that injected across the anode-cathode gap using plasma guns prior to the start of diode current. The injected plasma may reduce the impedance of PFRPD and enhance the dose rate of X-rays. A PIC simulating model of PFRPD is established. The beam pinching situation is described by the axial distribution of electron deposition density (ADEDD) on the anode rod. A PFRPD experiment platform is established, where a 1 MV PFRPD is driven by Jianguang-Ⅰ accelerator low impedance state(1 MV/9 /40 ns). Experiment results indicate that the diode performs better prefilled with appropriate plasma. The diode impedance is reduced to 10 , X ray radiation dose is increased from 0.76 mGy to 3.19 mGy, axial spot is reduced from 9 mm to 4 mm.
2014,
26: 115101.
doi: 10.11884/HPLPB201426.115101
Abstract:
In NSC KIPT (National Science Center, Kharkov Institute of Physics and Technology, Ukraine), a 100 MeV/100 kW electron linear accelerator has been developed. In order to ensure the performance of electron beam, two sets of transverse beam size monitor are installed in the injector segment and the transport line respectively. Due to the kilowatt level of the beam power, it is very difficult to find suitable materials for the beam-touching monitor. This paper introduced the simulation on the interaction between lames and beam with ANSYS, and the results of the vacuum temperature and deformation of lames were gotten. An initial beam experiment was done, and the output signals from the T300 carbon fiber bundles were measured under the test beam condition. The T300 carbon fiber bundle was chosen as the electrode material of the lame screen monitor. The mechanical design and signal processing system are very complex and dozens of signals were exported through the active vacuum components of the LSM.
In NSC KIPT (National Science Center, Kharkov Institute of Physics and Technology, Ukraine), a 100 MeV/100 kW electron linear accelerator has been developed. In order to ensure the performance of electron beam, two sets of transverse beam size monitor are installed in the injector segment and the transport line respectively. Due to the kilowatt level of the beam power, it is very difficult to find suitable materials for the beam-touching monitor. This paper introduced the simulation on the interaction between lames and beam with ANSYS, and the results of the vacuum temperature and deformation of lames were gotten. An initial beam experiment was done, and the output signals from the T300 carbon fiber bundles were measured under the test beam condition. The T300 carbon fiber bundle was chosen as the electrode material of the lame screen monitor. The mechanical design and signal processing system are very complex and dozens of signals were exported through the active vacuum components of the LSM.
2014,
26: 115102.
doi: 10.11884/HPLPB201426.115102
Abstract:
Technology index of the optical imaging system was designed for the purpose of accelerator deuterium ion beam profile measurement. ZEMAX was used to design and simulate the optical imaging system. The standard white light source and line pair board were used to check the design result. It was shown from the design result that this optical imaging system had good image quality. Distortion was lower than 0.05%. The MTFs of the center field and the edge field were higher than 0.7 with an optical resolution of 30 lp/mm. The experiment result of the optical imaging system used in the beam profile measurement showed that the diagnostic method based on scintillator screen was feasible.
Technology index of the optical imaging system was designed for the purpose of accelerator deuterium ion beam profile measurement. ZEMAX was used to design and simulate the optical imaging system. The standard white light source and line pair board were used to check the design result. It was shown from the design result that this optical imaging system had good image quality. Distortion was lower than 0.05%. The MTFs of the center field and the edge field were higher than 0.7 with an optical resolution of 30 lp/mm. The experiment result of the optical imaging system used in the beam profile measurement showed that the diagnostic method based on scintillator screen was feasible.
2014,
26: 115103.
doi: 10.11884/HPLPB201426.115103
Abstract:
This paper represents a systematic methodology to establish design requirements for the real-time data exchange between the industrial control computer based on Compact PCI and the device controller of heavy ion accelerator. The system core models include, PCI model based on FPGA which achieves PCI configuration and PCI master controller, DSP HPI controller which can transport data from FIFO to SDRAM or vice versa, and PCI device driver on microsoft Windows 7. The paper describes in detail how logic models cooperate with each other. Especially when DMA is executing, signals of FIFO for data exchange are used to control PCI master state machine and HPI state machine. Additionally, an interrupt INTA# is sent to Windows 7 as soon as DAM is finished. For verifying the feasibility of the system, a test application is designed which can non-stop write data to SDRAM by DMA or read data from SDRAM to memory by the same way. Thorough checking of the system shows rigorous conformance to the requirements of heavy ion synchrotron running.
This paper represents a systematic methodology to establish design requirements for the real-time data exchange between the industrial control computer based on Compact PCI and the device controller of heavy ion accelerator. The system core models include, PCI model based on FPGA which achieves PCI configuration and PCI master controller, DSP HPI controller which can transport data from FIFO to SDRAM or vice versa, and PCI device driver on microsoft Windows 7. The paper describes in detail how logic models cooperate with each other. Especially when DMA is executing, signals of FIFO for data exchange are used to control PCI master state machine and HPI state machine. Additionally, an interrupt INTA# is sent to Windows 7 as soon as DAM is finished. For verifying the feasibility of the system, a test application is designed which can non-stop write data to SDRAM by DMA or read data from SDRAM to memory by the same way. Thorough checking of the system shows rigorous conformance to the requirements of heavy ion synchrotron running.
2014,
26: 119001.
doi: 10.11884/HPLPB201426.119001
Abstract:
This paper analyzed the characteristics of laser-induced breakdown spectroscopy (LIBS) of metal element arsenic in soil using the Nd:YAG (wavelength: 1064 nm) laser as the excitation source, where the spectral signals were detected by the high resolved, wide spectral ECHELLE spectrograph and intensity charged coupled device (ICCD). The time evolution of the characteristic spectral line of arsenic was obtained by changing the delay time of ICCD at the same concentration and the gate of ICCD with wavelength of 228.8 nm of arsenic as the characteristic spectral line, from which a best delay time of 1 s and a gate width of 2 s were found. By measuring the intensities of the characteristic spectral line with different arsenic concentrations, it was demonstrated that the intensities of the spectral line increased with the concentration of arsenic under the condition of low concentration. From the results, the LIBS calibration curve of arsenic was obtained, and the detection limit of arsenic in soil at 45 mg/kg was obtained.
This paper analyzed the characteristics of laser-induced breakdown spectroscopy (LIBS) of metal element arsenic in soil using the Nd:YAG (wavelength: 1064 nm) laser as the excitation source, where the spectral signals were detected by the high resolved, wide spectral ECHELLE spectrograph and intensity charged coupled device (ICCD). The time evolution of the characteristic spectral line of arsenic was obtained by changing the delay time of ICCD at the same concentration and the gate of ICCD with wavelength of 228.8 nm of arsenic as the characteristic spectral line, from which a best delay time of 1 s and a gate width of 2 s were found. By measuring the intensities of the characteristic spectral line with different arsenic concentrations, it was demonstrated that the intensities of the spectral line increased with the concentration of arsenic under the condition of low concentration. From the results, the LIBS calibration curve of arsenic was obtained, and the detection limit of arsenic in soil at 45 mg/kg was obtained.
Measurement and numerical simulation of temperature field of laser deposition of TA15 titanium alloy
2014,
26: 119002.
doi: 10.11884/HPLPB201426.119002
Abstract:
The finite element model is built for laser deposition repair process based on comprehensive consideration of the heat source model, heat transfer of convection and radiation, phase change latent heat and nonlinear factors of material. Then a numerical simulation of temperature field of multi-pass and multi-layer laser deposition repair is conducted using ANSYS parametric design language. The distribution of transient temperature field are studied at different time, and change of temperature and the distribution of temperature gradient of different nodes along center height of the repaired parts are analyzed. A temperature measurement system of laser deposition repair is established to test surface temperature of the repaired parts, and a good agreement is observed between the calculated temperature and the experimental results. It is found that thermal simulation of laser deposition repair is an effective way to control the microstructure of laser deposition repaired parts and improve the quality of repair.
The finite element model is built for laser deposition repair process based on comprehensive consideration of the heat source model, heat transfer of convection and radiation, phase change latent heat and nonlinear factors of material. Then a numerical simulation of temperature field of multi-pass and multi-layer laser deposition repair is conducted using ANSYS parametric design language. The distribution of transient temperature field are studied at different time, and change of temperature and the distribution of temperature gradient of different nodes along center height of the repaired parts are analyzed. A temperature measurement system of laser deposition repair is established to test surface temperature of the repaired parts, and a good agreement is observed between the calculated temperature and the experimental results. It is found that thermal simulation of laser deposition repair is an effective way to control the microstructure of laser deposition repaired parts and improve the quality of repair.
2014,
26: 119003.
doi: 10.11884/HPLPB201426.119003
Abstract:
Simulation of laser shock peening with one round gauss-spot was carried out by ABAQUS FEM software. A residual stress hole phenomena in the material surface was detected. The formation mechanism of residual stress hole was explained via analyzing the dynamic mechanics response of the material in the spot center. The results indicate that intense shear stress is generated during the loading of laser-induced shock wave, and rarefaction wave and shear wave are formed. Rarefaction wave spreads all around in the material surface and shear wave propagates inward. When the ambient rarefaction waves meet and converge in the spot center, the material rises and falls sharply and secondary plastic deformation is generated. Because of the secondary plastic deformation, a large shear plastic stain is formed and the axial and radial plastic strain which were formed under the laser-induced shock wave, are greatly reduced. After the secondary plastic deformation, the residual stress reducing in the spot center results in the residual stress hole.
Simulation of laser shock peening with one round gauss-spot was carried out by ABAQUS FEM software. A residual stress hole phenomena in the material surface was detected. The formation mechanism of residual stress hole was explained via analyzing the dynamic mechanics response of the material in the spot center. The results indicate that intense shear stress is generated during the loading of laser-induced shock wave, and rarefaction wave and shear wave are formed. Rarefaction wave spreads all around in the material surface and shear wave propagates inward. When the ambient rarefaction waves meet and converge in the spot center, the material rises and falls sharply and secondary plastic deformation is generated. Because of the secondary plastic deformation, a large shear plastic stain is formed and the axial and radial plastic strain which were formed under the laser-induced shock wave, are greatly reduced. After the secondary plastic deformation, the residual stress reducing in the spot center results in the residual stress hole.
2014,
26: 112005.
doi: 10.11884/HPLPB201426.112005
Abstract:
This paper presents the results of high-temperature X-ray diffraction (XRD) study and temperature dependency analysis of the dielectric of BaTiO3(Ni) thin film on the SrTiO3 substrate. The results show that the phase transition temperature of a BaTiO3(Ni) thin film has a wide range. The tetragonal to cubic phase transition of BaTiO3(Ni) thin film was reversible, but the reversible phase transition didnt occur immediately after cooling process. The dielectric dispersion of BaTiO3(Ni)/SrTiO3 was caused by the stress and the mismatch between BaTiO3 thin film and the SrTiO3 substrate, and the effect of Ni nanocrystals. The dielectric relaxation was deviation from the Deby relaxation, and the dielectric loss increased with the increase of temperature. The results from the Cole-Cole plot show that the tetragonal to cubic phase transition of BaTiO3(Ni) thin film included several polarization mechanisms function. The dielectric loss increased with the increase of temperature at a high temperature. The film was not restored tetragonal phase immediately in the cooling process, which might be the combined effect of both substrate and Ni particles.
This paper presents the results of high-temperature X-ray diffraction (XRD) study and temperature dependency analysis of the dielectric of BaTiO3(Ni) thin film on the SrTiO3 substrate. The results show that the phase transition temperature of a BaTiO3(Ni) thin film has a wide range. The tetragonal to cubic phase transition of BaTiO3(Ni) thin film was reversible, but the reversible phase transition didnt occur immediately after cooling process. The dielectric dispersion of BaTiO3(Ni)/SrTiO3 was caused by the stress and the mismatch between BaTiO3 thin film and the SrTiO3 substrate, and the effect of Ni nanocrystals. The dielectric relaxation was deviation from the Deby relaxation, and the dielectric loss increased with the increase of temperature. The results from the Cole-Cole plot show that the tetragonal to cubic phase transition of BaTiO3(Ni) thin film included several polarization mechanisms function. The dielectric loss increased with the increase of temperature at a high temperature. The film was not restored tetragonal phase immediately in the cooling process, which might be the combined effect of both substrate and Ni particles.
