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RSS2004 Vol. 16, No. 03
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2004,
16.
Abstract:
Coaxial slow wave structure (SWS) is the most important part in MILO. According to the Maxwell equations and Floquet theorem, the dispersion relation of several TM0 n modes in MILO coaxial SWS is educed in this paper. Through numerical calculation, the impacts of several structure parameters of MILO coaxial SWS on its high frequency characteristic are analyzed, and the results are useful to the design of MILO．
Coaxial slow wave structure (SWS) is the most important part in MILO. According to the Maxwell equations and Floquet theorem, the dispersion relation of several TM0 n modes in MILO coaxial SWS is educed in this paper. Through numerical calculation, the impacts of several structure parameters of MILO coaxial SWS on its high frequency characteristic are analyzed, and the results are useful to the design of MILO．
2004,
16.
Abstract:
The distribution of the current density in the wire and induced current density within the armature for a Helical magnetic flux compression generator(HMFCG) are studied based on the solutions of the current and magnetic field diffusion equations,The HMFCG inductance and resistance are calculated analytically during the transient process, and the agreement between the numerical one and the experimental results are quite satisfactory．
The distribution of the current density in the wire and induced current density within the armature for a Helical magnetic flux compression generator(HMFCG) are studied based on the solutions of the current and magnetic field diffusion equations,The HMFCG inductance and resistance are calculated analytically during the transient process, and the agreement between the numerical one and the experimental results are quite satisfactory．
2004,
16.
Abstract:
Input cavity transforms the H10 mode in waveguide to H011 mode in inner resonant cavity, H011 mode is used to modulate the transverse velocity of gyroelectron beam. In this paper, an approximate analysis method is presented, theoretical analysis and numerical calculations have been completed, and then primitive structure and geometric parameters of the input cavity can be obtained in minutes. Afterward, HFSS code is used to simulate accurately and revise approximate analysis. Based on a large number of calculations and simulations, the optimal input cavity meeting the design requirement is attained.
Input cavity transforms the H10 mode in waveguide to H011 mode in inner resonant cavity, H011 mode is used to modulate the transverse velocity of gyroelectron beam. In this paper, an approximate analysis method is presented, theoretical analysis and numerical calculations have been completed, and then primitive structure and geometric parameters of the input cavity can be obtained in minutes. Afterward, HFSS code is used to simulate accurately and revise approximate analysis. Based on a large number of calculations and simulations, the optimal input cavity meeting the design requirement is attained.
2004,
16.
Abstract:
After analyzing the design process with previous electron beam optics simulation and modeling tools and their shortcomings, this paper presents that MAFIA PIC simulation is a more accurate method as it can wholly support spacechargelimited (Child's law) and temperaturelimited emission, cathode thermal initial velocity and nonlaminar flow. The 3dimensional timedependent PIC code is also desired for studying the beam transient and noise character. Using MAFIA PIC code to simulate an electron gun, some useful data are obtained, which show that the simulation results are close to the experimental data within acceptable error range. It can be used to instruct the engineering design of microwave tube electron optics.
After analyzing the design process with previous electron beam optics simulation and modeling tools and their shortcomings, this paper presents that MAFIA PIC simulation is a more accurate method as it can wholly support spacechargelimited (Child's law) and temperaturelimited emission, cathode thermal initial velocity and nonlaminar flow. The 3dimensional timedependent PIC code is also desired for studying the beam transient and noise character. Using MAFIA PIC code to simulate an electron gun, some useful data are obtained, which show that the simulation results are close to the experimental data within acceptable error range. It can be used to instruct the engineering design of microwave tube electron optics.
2004,
16.
Abstract:
A kind of Sband frequency agile relativistic magnetron is designed, which adopts the scheme of risingsun magnetron with 5 fanshaped cavities and 5 rectangular cavities. Through adjusting the site of metallic block in the rectangular cavities, the system's syntonic frequency gets altered. The method of equivalent circuit, the software of highfrequency structure simulator (HFSS) and MAGIC are used to analyse and simulate this device. Initial results show that 20% relative bandwidth, minimum output power 600MW can be gotten in this frequency agile relativistic magnetron, when operating voltage is 650kV with 0.1ns rise time and magnet field of 0.6T respectively.
A kind of Sband frequency agile relativistic magnetron is designed, which adopts the scheme of risingsun magnetron with 5 fanshaped cavities and 5 rectangular cavities. Through adjusting the site of metallic block in the rectangular cavities, the system's syntonic frequency gets altered. The method of equivalent circuit, the software of highfrequency structure simulator (HFSS) and MAGIC are used to analyse and simulate this device. Initial results show that 20% relative bandwidth, minimum output power 600MW can be gotten in this frequency agile relativistic magnetron, when operating voltage is 650kV with 0.1ns rise time and magnet field of 0.6T respectively.
2004,
16.
Abstract:
A novel resonator for transit time tube is put out and the interaction between the electron beam and the eigenmode in the resonant, with the 2.5 dimensional partical simulation code. The simulation indicated that the electron beam can well interact with the eigenmode in three and four cavity resonant. An Xband transit time tube oscillator is designed. With the voltage 760kV, the current 6kA and the magnetic field 2.6T in the simulation, the output power is about 1.7GW and interaction efficiency is about 37%.
A novel resonator for transit time tube is put out and the interaction between the electron beam and the eigenmode in the resonant, with the 2.5 dimensional partical simulation code. The simulation indicated that the electron beam can well interact with the eigenmode in three and four cavity resonant. An Xband transit time tube oscillator is designed. With the voltage 760kV, the current 6kA and the magnetic field 2.6T in the simulation, the output power is about 1.7GW and interaction efficiency is about 37%.
2004,
16.
Abstract:
Measured CW amplitude spectrum data are often obtained in EMP research, especially in effects experiments and probe calibration. This paper investigates the minimum phase reconstruction of the transient waveform from amplitude spectrum data. This technique involves the use of Hilbert transform, an assumption of minimum phase and cepstrum. The reconstruction of minimum phase signal, such as the HEMP waveform, cosine or sine exponentially damped waveform etc, shows good agreement with the original. For nonminimum phase signal, the total energy, the approximate amplitude and shape of the waveform can be indicated although the rise (fall) time and peak value are different from the original.
Measured CW amplitude spectrum data are often obtained in EMP research, especially in effects experiments and probe calibration. This paper investigates the minimum phase reconstruction of the transient waveform from amplitude spectrum data. This technique involves the use of Hilbert transform, an assumption of minimum phase and cepstrum. The reconstruction of minimum phase signal, such as the HEMP waveform, cosine or sine exponentially damped waveform etc, shows good agreement with the original. For nonminimum phase signal, the total energy, the approximate amplitude and shape of the waveform can be indicated although the rise (fall) time and peak value are different from the original.
2004,
16.
Abstract:
The main part of quasi-periodic RF cavity is the periodic structure. With the strong leading magnet field, the relativistic electron beam can produce high power microwave in such cavity. The interaction between the beam and the microwave field can be divided into three processes: electron capture, bunch and electron momentum turning into microwave field. The role of the main part is for electron capture. High efficiency and high microwave power can be obtained with optimized cavity. In this paper, the electron movement is studied under the action of the microwave field in the cavity, and electron capture and bunch are also explored. In the simulation, the output power of 1.3GW is obtained at X-band(9.3GHz) using such cavity driven by ring beam, whose parameters are 760kV and 7kA, and the e
The main part of quasi-periodic RF cavity is the periodic structure. With the strong leading magnet field, the relativistic electron beam can produce high power microwave in such cavity. The interaction between the beam and the microwave field can be divided into three processes: electron capture, bunch and electron momentum turning into microwave field. The role of the main part is for electron capture. High efficiency and high microwave power can be obtained with optimized cavity. In this paper, the electron movement is studied under the action of the microwave field in the cavity, and electron capture and bunch are also explored. In the simulation, the output power of 1.3GW is obtained at X-band(9.3GHz) using such cavity driven by ring beam, whose parameters are 760kV and 7kA, and the e
2004,
16.
Abstract:
An important nature of the double-exponential function, which is used to describe the typical high-altitude electromagnetic pulse (HEMP) waveform in many standards and publications, is studied by the numerical method. Based on the function nature it is discussed in details the relation of the physical parameters of the simulated HEMP waveform and the character parameters of the double-exponential function. Here the physical parameters of HEMP include peak value, rise time, fall time and full-width at half-maximum amplitude (FWHM). A simple and effective method is proposed to evaluate the character parameters of the function from the physical parameters. And it's effectivity and reliability is validated by evaluating the HEMP parameters defined by IEC and by the numerical fitting of a measu
An important nature of the double-exponential function, which is used to describe the typical high-altitude electromagnetic pulse (HEMP) waveform in many standards and publications, is studied by the numerical method. Based on the function nature it is discussed in details the relation of the physical parameters of the simulated HEMP waveform and the character parameters of the double-exponential function. Here the physical parameters of HEMP include peak value, rise time, fall time and full-width at half-maximum amplitude (FWHM). A simple and effective method is proposed to evaluate the character parameters of the function from the physical parameters. And it's effectivity and reliability is validated by evaluating the HEMP parameters defined by IEC and by the numerical fitting of a measu
2004,
16.
Abstract:
The disadvantages of the uniform slowwave structure in Cerenkov beamwave interaction are analyzed. It is put forward that in the sectional slowwave structure, the drift tube and the two section SWSs of its ends comprise a Bragg resonant cavity, which can reduce the energy dispersal of the modulated beam electrons due to the transit time effect when the length of the drift tube is well chosen, thus to enhance the beamwave energy conversion efficiency. By means of the PIC simulation, physical graphs of beamwave interaction in the uniform slowwave structure case and in the sectional slowwave structure case are compared, and the simulation results confirm that the latter has several advantages, such as more effective beamwave energy conversion efficiency, better spectrum qualit
The disadvantages of the uniform slowwave structure in Cerenkov beamwave interaction are analyzed. It is put forward that in the sectional slowwave structure, the drift tube and the two section SWSs of its ends comprise a Bragg resonant cavity, which can reduce the energy dispersal of the modulated beam electrons due to the transit time effect when the length of the drift tube is well chosen, thus to enhance the beamwave energy conversion efficiency. By means of the PIC simulation, physical graphs of beamwave interaction in the uniform slowwave structure case and in the sectional slowwave structure case are compared, and the simulation results confirm that the latter has several advantages, such as more effective beamwave energy conversion efficiency, better spectrum qualit
Analysis on shielding effectiveness of rectangular cavity with apertures by transmission line method
2004,
16.
Abstract:
This article firstly introduces the basic theory of transmission line method(TLM) which is used to analyze shielding effectiveness of rectangular enclosure with apertures,then expands the fundamental formulas to deal with cases of round hole,multiholes, and arbitrary angle of polarization. Simulation results indicate: (1)when the frequency is under dominant resonant frequency, the closer to the enclosure, the more coupling energy; (2)under resonant frequency, resonance appears between the aperture and the enclosure, which results in low even negative shielding effectiveness in the cavity; (3)sielding effectiveness decreases when polarization angle increases, and shielding of low frequency is better than that of high frequency; (4)fr the same areas, shielding effectiveness of singlehole
This article firstly introduces the basic theory of transmission line method(TLM) which is used to analyze shielding effectiveness of rectangular enclosure with apertures,then expands the fundamental formulas to deal with cases of round hole,multiholes, and arbitrary angle of polarization. Simulation results indicate: (1)when the frequency is under dominant resonant frequency, the closer to the enclosure, the more coupling energy; (2)under resonant frequency, resonance appears between the aperture and the enclosure, which results in low even negative shielding effectiveness in the cavity; (3)sielding effectiveness decreases when polarization angle increases, and shielding of low frequency is better than that of high frequency; (4)fr the same areas, shielding effectiveness of singlehole
2004,
16.
Abstract:
The metal doped resorcinol-formaldehyde gels are important target materials in inertial confinement fusion research,especially for application foreground of low-temperature freeze target research. In this paper ,resorcinol,formaldehyde and titanium nanoparticles are used as reactants, titanium nanoparticles are doped into RF gels successfully by physic method. In gelation process, the particle-diameter distributions are measured by zetasizer. The result indicates that the best dispersant for titanium nanoparticles is (NaPO3)6 and after doped, gelation time is shortened．The variety and dosage of dispersamts can influce the gelation time. The dosage of dispersomts should be as 50~100 times as that of titanium nanoparticles．
The metal doped resorcinol-formaldehyde gels are important target materials in inertial confinement fusion research,especially for application foreground of low-temperature freeze target research. In this paper ,resorcinol,formaldehyde and titanium nanoparticles are used as reactants, titanium nanoparticles are doped into RF gels successfully by physic method. In gelation process, the particle-diameter distributions are measured by zetasizer. The result indicates that the best dispersant for titanium nanoparticles is (NaPO3)6 and after doped, gelation time is shortened．The variety and dosage of dispersamts can influce the gelation time. The dosage of dispersomts should be as 50~100 times as that of titanium nanoparticles．
2004,
16.
Abstract:
In this paper, taking type I/II angledetuning scheme as an example, the effect of phase perturbation and amplitude modulation of the high power incident fundamental field on phase perturbation of the tripling field has been discussed in details. The transformation relation between the phase perturbation of fundamental field and tripling field has been analyzed quantitatively. The results of simulation indicate that the amplitude of phase perturbation of the tripling field is about three times as that of the fundamental field. The effect of phase perturbation of the fundamental field on the phase distribution of the tripling field is much more important than that of the amplitude modulation. However, the effect of the amplitude modulation becomes more important as the power density of the
In this paper, taking type I/II angledetuning scheme as an example, the effect of phase perturbation and amplitude modulation of the high power incident fundamental field on phase perturbation of the tripling field has been discussed in details. The transformation relation between the phase perturbation of fundamental field and tripling field has been analyzed quantitatively. The results of simulation indicate that the amplitude of phase perturbation of the tripling field is about three times as that of the fundamental field. The effect of phase perturbation of the fundamental field on the phase distribution of the tripling field is much more important than that of the amplitude modulation. However, the effect of the amplitude modulation becomes more important as the power density of the
2004,
16.
Abstract:
This paper presents the fabrication of lowdensity silicon dioxide aerogel microspheres and the sol-gel transition process. The work covers the effects of suspension spheres, the density-match and aging time on the properties of resultant aerogel spheres, focusing on the shrinkage effects. Four different density microspheres are studied with expected density of 70mg/cm3, 100mg/cm3, 150mg/cm3 and 200mg/cm3 respectively. The results show that we can obtain microspheres with diameter from 0.1mm up to 2mm, and density in the range of 50~500mg/cm3,and the parameter of out of round is 1.8%．
This paper presents the fabrication of lowdensity silicon dioxide aerogel microspheres and the sol-gel transition process. The work covers the effects of suspension spheres, the density-match and aging time on the properties of resultant aerogel spheres, focusing on the shrinkage effects. Four different density microspheres are studied with expected density of 70mg/cm3, 100mg/cm3, 150mg/cm3 and 200mg/cm3 respectively. The results show that we can obtain microspheres with diameter from 0.1mm up to 2mm, and density in the range of 50~500mg/cm3,and the parameter of out of round is 1.8%．
2004,
16.
Abstract:
TiO２ photosensitive gel films are derived from chemically modified metalalkoxide with benzoylacetone by sol-gel process. The gel films show an absorption band at around 360 nm, characteristic of the remaining chelate rings. The negative tone gel films are irradiated by UV light through a mask with different pattern to prepare grating pattern on gel films. Depending on the exposure time, the gel films are leaching with ethanol and the grating with different structure on TiO2 photosensitive gel films are obtained．
TiO２ photosensitive gel films are derived from chemically modified metalalkoxide with benzoylacetone by sol-gel process. The gel films show an absorption band at around 360 nm, characteristic of the remaining chelate rings. The negative tone gel films are irradiated by UV light through a mask with different pattern to prepare grating pattern on gel films. Depending on the exposure time, the gel films are leaching with ethanol and the grating with different structure on TiO2 photosensitive gel films are obtained．
2004,
16.
Abstract:
A kind of measurement of image segmentation based on the principle of optical interference is presented and realized by simulation in computer. A uniform coherent light source, a filter and a receiving screen are designed in computer. The pseud phase distribution, which is translated from intensity distribution of the image by a conversion rule, is shown on this given filter. The interference pattern is produced when the filter is illuminated with the light source, and sampled on a receiving screen. Choosing a proper threshold segments the interference pattern and the edge of the input image can be obtained. Numerical simulation shows the effect of this segmentation method is equivalent to that of Sobel operator.Contrast between simulated results and experimental results is analyzed. It in
A kind of measurement of image segmentation based on the principle of optical interference is presented and realized by simulation in computer. A uniform coherent light source, a filter and a receiving screen are designed in computer. The pseud phase distribution, which is translated from intensity distribution of the image by a conversion rule, is shown on this given filter. The interference pattern is produced when the filter is illuminated with the light source, and sampled on a receiving screen. Choosing a proper threshold segments the interference pattern and the edge of the input image can be obtained. Numerical simulation shows the effect of this segmentation method is equivalent to that of Sobel operator.Contrast between simulated results and experimental results is analyzed. It in
2004,
16.
Abstract:
The basic theory of a beam passing through the nonlinear medium is analysed in this paper, and the process of a tenstep high power supperGaussion beam passing through the nonlinear medium is calculated with the FFT. A negative nonlinear refractive index material was used as the compensating medium to compare different compensation methods. Studies suggest compensation can decrease B integral along the beam direction in a nonlinear medium, and can cancel the selffocusing of beams greatly. It can also avoid the nonlinear increase on the edges of superGaussian beams effectively. The compensation after nonlinear medium was selected as the idea compensating methods.
The basic theory of a beam passing through the nonlinear medium is analysed in this paper, and the process of a tenstep high power supperGaussion beam passing through the nonlinear medium is calculated with the FFT. A negative nonlinear refractive index material was used as the compensating medium to compare different compensation methods. Studies suggest compensation can decrease B integral along the beam direction in a nonlinear medium, and can cancel the selffocusing of beams greatly. It can also avoid the nonlinear increase on the edges of superGaussian beams effectively. The compensation after nonlinear medium was selected as the idea compensating methods.
2004,
16.
Abstract:
In this paper, two methods were used to get the atmospheric coherent length of slope way in the atmospheric boundary layer. A set of microthermal sensor was installed on a 32 meters high tower, it was used to get the turbulence profile together with a Doppler sodar. The atmospheric coherent length could be gained from the integral of turbulence profile. A small bulb was hoisted with a kite balloon, a difference optical system was used to measure the atmospheric coherent length from fluctuation of arrival angle.The results of both these two methods could show the character of temporal variation. The correlation of the results was quite well. At last, some problems of getting atmospheric coherent length from the integral of turbulence profile were discussed．
In this paper, two methods were used to get the atmospheric coherent length of slope way in the atmospheric boundary layer. A set of microthermal sensor was installed on a 32 meters high tower, it was used to get the turbulence profile together with a Doppler sodar. The atmospheric coherent length could be gained from the integral of turbulence profile. A small bulb was hoisted with a kite balloon, a difference optical system was used to measure the atmospheric coherent length from fluctuation of arrival angle.The results of both these two methods could show the character of temporal variation. The correlation of the results was quite well. At last, some problems of getting atmospheric coherent length from the integral of turbulence profile were discussed．
2004,
16.
Abstract:
The absorption of optical thin film coatings is one of the main factors that limit the development of high power lasers. It is necessary to measure the absorption of the optical thin film coatings precisely, fast and in real-time. The experimental setup for measuring the weak absorption of the optical thin films has been built using the surface thermal lensing technique. The weak absorption of different optical thin films, including the single-layer ZnS and YbF3 dielectric thin films with different thickness, as well as the different multilayer thin films (YbF3/ ZnS) deposited on Ge substrate, irradiated by 10.6μm CO2 laser has been measured. The experimental results show that the lowest absorption measured by the experimental system is 2.87×10－4 and the sensitivity of the experim
The absorption of optical thin film coatings is one of the main factors that limit the development of high power lasers. It is necessary to measure the absorption of the optical thin film coatings precisely, fast and in real-time. The experimental setup for measuring the weak absorption of the optical thin films has been built using the surface thermal lensing technique. The weak absorption of different optical thin films, including the single-layer ZnS and YbF3 dielectric thin films with different thickness, as well as the different multilayer thin films (YbF3/ ZnS) deposited on Ge substrate, irradiated by 10.6μm CO2 laser has been measured. The experimental results show that the lowest absorption measured by the experimental system is 2.87×10－4 and the sensitivity of the experim
2004,
16.
Abstract:
The conventional methods of image matching are based on gray and shape of image. These two features can't describe image data well especially in tracking the faint and small targets. It's difficult to track the target with highprecision and steady. In this paper, a new algorithm of image matching was proposed. It extracts characters including gray and shape from image data and gains an integrated character using the information fusion algorithm with simplicity and effect. Then calculates the position coordinate of target using integrated characteristics by correlation degree. Simulation shows that the method is feasible and effective.
The conventional methods of image matching are based on gray and shape of image. These two features can't describe image data well especially in tracking the faint and small targets. It's difficult to track the target with highprecision and steady. In this paper, a new algorithm of image matching was proposed. It extracts characters including gray and shape from image data and gains an integrated character using the information fusion algorithm with simplicity and effect. Then calculates the position coordinate of target using integrated characteristics by correlation degree. Simulation shows that the method is feasible and effective.
2004,
16.
Abstract:
This paper introduces the typical characteristics of AML-1 mobile lidar, which is the first mobile lidar of China. This lidar can be used to measure aerosols at daytime when receiver angle matches transmitter angle well and high transmission interference filter is used. It also can be used to measure aerosols at different zenith angle because it has 3D scanning device. All these may have great significance for realizing continual, simultaneous, large-ranged atmospheric pollution detecting. The results show great stability and reliability of AML-1 mobile lidar comparing with other lidars. Typical aerosol profiles and space-time distributing diagrams are shown and discussed at vertical，slant and 2D scanning aspects.
This paper introduces the typical characteristics of AML-1 mobile lidar, which is the first mobile lidar of China. This lidar can be used to measure aerosols at daytime when receiver angle matches transmitter angle well and high transmission interference filter is used. It also can be used to measure aerosols at different zenith angle because it has 3D scanning device. All these may have great significance for realizing continual, simultaneous, large-ranged atmospheric pollution detecting. The results show great stability and reliability of AML-1 mobile lidar comparing with other lidars. Typical aerosol profiles and space-time distributing diagrams are shown and discussed at vertical，slant and 2D scanning aspects.
2004,
16.
Abstract:
The size of X-ray source is always an important parameter which influences the imaging definition．In high energy X-ray radiography system，the especial conditions will prick up this affection．The calculating model is set up based on the theory of stage imaging theory，and the influence on the system's spatial resolution is simulated in this paper．The methods of reducing the influence are also introduced．
The size of X-ray source is always an important parameter which influences the imaging definition．In high energy X-ray radiography system，the especial conditions will prick up this affection．The calculating model is set up based on the theory of stage imaging theory，and the influence on the system's spatial resolution is simulated in this paper．The methods of reducing the influence are also introduced．
2004,
16.
Abstract:
In the last few years, the study of nitrogen incorporation into diamondlike carbon (DLC)films has received special attention. The DLC films have been deposited on glass substrates using RF plasma deposition method. N ions were introduced by ion implantation, and DLC(N) films were irradiated by ultraviolet light. Using Raman and infrared transimissing spectroscopy, the authors investigated the UV ray irradiation and N ions implantation effect on the structure and properties of DLC(N) films. The study showes that, UV ray and N ions irradiation does intensive damage on SP3C-H bonds, then leads to the increase of SP2C-H bonds and the decrease of resistivity obviously. It is clear that UV ray causes the increase of Si-O-Si and Si-C bonds also, i.e. the structure and properties of DLC films ha
In the last few years, the study of nitrogen incorporation into diamondlike carbon (DLC)films has received special attention. The DLC films have been deposited on glass substrates using RF plasma deposition method. N ions were introduced by ion implantation, and DLC(N) films were irradiated by ultraviolet light. Using Raman and infrared transimissing spectroscopy, the authors investigated the UV ray irradiation and N ions implantation effect on the structure and properties of DLC(N) films. The study showes that, UV ray and N ions irradiation does intensive damage on SP3C-H bonds, then leads to the increase of SP2C-H bonds and the decrease of resistivity obviously. It is clear that UV ray causes the increase of Si-O-Si and Si-C bonds also, i.e. the structure and properties of DLC films ha
Characters of γray irradiated scintillation optical fiber by simulation based on Monte Carlo method
2004,
16.
Abstract:
Scintillation optical fiber is applied to ray imaging more and more widely. In order to know more about some characters of scintillation optical fiber under ray radiation, the article analyses the relationships between good event rate of γray and fiber length and ray energy, and between energy deposition efficiency of γray and fiber length and ray energy by computer simulation based on Monte Carlo method. According to them, we can conclude some important results. For example, the scintillation fiber′s optimal length is about 10cm when applying it to imaging; its detecting efficiency is higher under low incident photons and lower under high incident photons. The work is very useful in the field of scintillation fiber imaging and dosage measurement.
Scintillation optical fiber is applied to ray imaging more and more widely. In order to know more about some characters of scintillation optical fiber under ray radiation, the article analyses the relationships between good event rate of γray and fiber length and ray energy, and between energy deposition efficiency of γray and fiber length and ray energy by computer simulation based on Monte Carlo method. According to them, we can conclude some important results. For example, the scintillation fiber′s optimal length is about 10cm when applying it to imaging; its detecting efficiency is higher under low incident photons and lower under high incident photons. The work is very useful in the field of scintillation fiber imaging and dosage measurement.
2004,
16.
Abstract:
The Xray source based on electron accelerator is the foundation of high energy industrial CT(ICT). A new type of small spot size SW electron linac was designed with high space resolution. This paper discusses that spot size of radial source influence on the imaging quality, and analyzes the physical reason that at high energy the small hole method wasn't suit for the measurement of spot size, it also gives four kinds of measurement method for this type of high energy Xray source spot size and the analysis of the experiment results. The measurement results show that spot size of the new type accelerator Xray source is about 1.4mm, and the limited space resolution is 2.5lp/mm.
The Xray source based on electron accelerator is the foundation of high energy industrial CT(ICT). A new type of small spot size SW electron linac was designed with high space resolution. This paper discusses that spot size of radial source influence on the imaging quality, and analyzes the physical reason that at high energy the small hole method wasn't suit for the measurement of spot size, it also gives four kinds of measurement method for this type of high energy Xray source spot size and the analysis of the experiment results. The measurement results show that spot size of the new type accelerator Xray source is about 1.4mm, and the limited space resolution is 2.5lp/mm.
2004,
16.
Abstract:
Improvement status of HLS ceramic chambers was presented. A new method of inner surface coating of ceramic chambers with Mo-metallization was developed. The rise time characteristic of the pulsed magnetic field was greatly improved. Injection rate of the storage ring increased after installation of the new chamber. A two-coil method of measuring magnetic field was established. The resolution of rise time reaches nano-second range and the waveforms of measurement were presented．
Improvement status of HLS ceramic chambers was presented. A new method of inner surface coating of ceramic chambers with Mo-metallization was developed. The rise time characteristic of the pulsed magnetic field was greatly improved. Injection rate of the storage ring increased after installation of the new chamber. A two-coil method of measuring magnetic field was established. The resolution of rise time reaches nano-second range and the waveforms of measurement were presented．
2004,
16.
Abstract:
This paper introduces the advantage, purpose, principle and design of selfintegral Rogowski coil for nslevel current measurement. The response and distribute of Rogowski coil are discussed. The coil with a shield is treated as a distributed circuit, so that the toroidally wound coil acts as a delay line. The coil is calibrated. This coil could get the signal with rise time less than 2ns, value 10A～40kA, sensitivities about 1.4mV/A, pulsed width less than 200ns. The coil can be used in pulsed power technology for nslevel high current measurement.
This paper introduces the advantage, purpose, principle and design of selfintegral Rogowski coil for nslevel current measurement. The response and distribute of Rogowski coil are discussed. The coil with a shield is treated as a distributed circuit, so that the toroidally wound coil acts as a delay line. The coil is calibrated. This coil could get the signal with rise time less than 2ns, value 10A～40kA, sensitivities about 1.4mV/A, pulsed width less than 200ns. The coil can be used in pulsed power technology for nslevel high current measurement.
2004,
16.
Abstract:
An intense electron beam is adopted in HIRFLCSR ecooler system to cool down heavy ion beams. In the drift space of the cooling section, the envelope of electron beam oscillates due to space charge field and solenoidal field. By solving the transversal envelope equation, the envelope oscillation of intense electron beam is preliminarily studied. The caculation results show that in the same case, the stronger the magnetic field is, the smaller the envelope oscillation is; meanwhile, the larger the beam energy is, the larger the oscillation frequency is．
An intense electron beam is adopted in HIRFLCSR ecooler system to cool down heavy ion beams. In the drift space of the cooling section, the envelope of electron beam oscillates due to space charge field and solenoidal field. By solving the transversal envelope equation, the envelope oscillation of intense electron beam is preliminarily studied. The caculation results show that in the same case, the stronger the magnetic field is, the smaller the envelope oscillation is; meanwhile, the larger the beam energy is, the larger the oscillation frequency is．
2004,
16.
Abstract:
By taking the magnetic flux compression generator(MFCG) as an equivalent current source, the analysis is carried out for transmission line charged by MFCG through a pulse transformer. The analytic expressions of the charging voltage and the charging current of the transmission line are obtained in the cases of linear and arbitrary load current. It is shown that the mutual inductance of pulse transformer and the slope of load current are the important parameters for the charging process. The amplitude of the first peak of charging voltage is proportional to the mutual inductance of pulse transformer, and approximately proportional to the slope of the load current. It is also found that the change of the slope may change the time of voltage peak, and the time of voltage peak will be delayed
By taking the magnetic flux compression generator(MFCG) as an equivalent current source, the analysis is carried out for transmission line charged by MFCG through a pulse transformer. The analytic expressions of the charging voltage and the charging current of the transmission line are obtained in the cases of linear and arbitrary load current. It is shown that the mutual inductance of pulse transformer and the slope of load current are the important parameters for the charging process. The amplitude of the first peak of charging voltage is proportional to the mutual inductance of pulse transformer, and approximately proportional to the slope of the load current. It is also found that the change of the slope may change the time of voltage peak, and the time of voltage peak will be delayed
2004,
16.
Abstract:
A generalized equation, which governs space charge current flow in three relativistic configurations, was derived from Poisson's equation with assumption of spacechargelimited flow. A method for solution to the equation was introduced and the characteristic of solution for the three configurations was discussed as well. It was found that the expressions of spacechargelimited flow for both the commonvertexcoaxialcircularcones and coaxial cylindrical conductors have polarity effect, which results in different distribution of space charge and electrical stress from that of planar case.
A generalized equation, which governs space charge current flow in three relativistic configurations, was derived from Poisson's equation with assumption of spacechargelimited flow. A method for solution to the equation was introduced and the characteristic of solution for the three configurations was discussed as well. It was found that the expressions of spacechargelimited flow for both the commonvertexcoaxialcircularcones and coaxial cylindrical conductors have polarity effect, which results in different distribution of space charge and electrical stress from that of planar case.
