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RSS2002 Vol. 14, No. 04
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2002,
14.
Abstract:
In electromagnetic imaging, ill-posed equations are unavoidable, which are very difficult to solve. The Genetic Algorithm (GA) is a numerical-optimization method. This paper analyzes the GA method and advantages in solving illposed equations of electromagnetic imaging. Two numeric simulations are presented. One is using GA to solve an ill-posed linear equation, and the other is using GA in 2D microwave imaging. Results of numeric simulations show that GA is effective in solving ill-posed equations and it is able to obtain good image reconstruction.
In electromagnetic imaging, ill-posed equations are unavoidable, which are very difficult to solve. The Genetic Algorithm (GA) is a numerical-optimization method. This paper analyzes the GA method and advantages in solving illposed equations of electromagnetic imaging. Two numeric simulations are presented. One is using GA to solve an ill-posed linear equation, and the other is using GA in 2D microwave imaging. Results of numeric simulations show that GA is effective in solving ill-posed equations and it is able to obtain good image reconstruction.
2002,
14.
Abstract:
A High Power Microwave square pyramidal Gaussian feed aperture field is analyzed by using the waveguide intrinsic mode expansion method. The key parameter is the Gaussian beam waist radius that is determinded by compromise of the radiation charateristics and breakdown avoidance. The mode ratios of the square waveguide multimodes can be calculated with the slected waist radius, that makes a base for designing a Gaussian feed by mode matching or coupling wave theory．
A High Power Microwave square pyramidal Gaussian feed aperture field is analyzed by using the waveguide intrinsic mode expansion method. The key parameter is the Gaussian beam waist radius that is determinded by compromise of the radiation charateristics and breakdown avoidance. The mode ratios of the square waveguide multimodes can be calculated with the slected waist radius, that makes a base for designing a Gaussian feed by mode matching or coupling wave theory．
2002,
14.
Abstract:
In order to have the high-power microwave(HPM) source of the three-unit transit-time tube oscillator(TTTO) has the character of unidirectional beam and line polarization, a circular waveguide bevel cut radiation antenna is designed. Experimental research is the emphatic part. Experiment condition as well as factors that should be considered during the design is presented. The length of the coaxial inner-conductor has been regulated, and the form of the nose taper has been choosed, which belong to the modes convertor in the front of the circular waveguide. Then, the better result s are finally presented. The reliability and practicality of this antenna have been proved.
In order to have the high-power microwave(HPM) source of the three-unit transit-time tube oscillator(TTTO) has the character of unidirectional beam and line polarization, a circular waveguide bevel cut radiation antenna is designed. Experimental research is the emphatic part. Experiment condition as well as factors that should be considered during the design is presented. The length of the coaxial inner-conductor has been regulated, and the form of the nose taper has been choosed, which belong to the modes convertor in the front of the circular waveguide. Then, the better result s are finally presented. The reliability and practicality of this antenna have been proved.
2002,
14.
Abstract:
The electromagnetic pulse radiation problem is the starting point for high power microwaves radiation, propagation and scattering. This paper applies the finite difference time domain technique(FDTD) combined with the timedomain measured equation of invariance method(MEI) to calculate line source radiation problem with near truncating boundary. The numerical results show that MEI boundary condition has high effect and high accuracy than two-order Mur boundary condition.
The electromagnetic pulse radiation problem is the starting point for high power microwaves radiation, propagation and scattering. This paper applies the finite difference time domain technique(FDTD) combined with the timedomain measured equation of invariance method(MEI) to calculate line source radiation problem with near truncating boundary. The numerical results show that MEI boundary condition has high effect and high accuracy than two-order Mur boundary condition.
Intense electromagnetic pulse induced breakdown effects in high temperature dissociated nitrogen gas
2002,
14.
Abstract:
A theoretical investigation on the intense electromagnetic pulse (EMP)induced breakdown process in high temperature nitrogen gas is given. The main character of high temperature gas isthat molecules in it dissociate in some degree, and this will affect the breakdown threshold of the EMP. Numerical calculations have revealed that: (1) The breakdown threshold of the EMP decreases as the gas temperature increases; (2) The degree for the decrease of breakdown threshold depends on the frequency of the electromagnetic wave.
A theoretical investigation on the intense electromagnetic pulse (EMP)induced breakdown process in high temperature nitrogen gas is given. The main character of high temperature gas isthat molecules in it dissociate in some degree, and this will affect the breakdown threshold of the EMP. Numerical calculations have revealed that: (1) The breakdown threshold of the EMP decreases as the gas temperature increases; (2) The degree for the decrease of breakdown threshold depends on the frequency of the electromagnetic wave.
2002,
14.
Abstract:
Unmagnetized plasma filled relativistic backward wave oscillator RBWO is analyzed by particleincell(PIC) simulation in this paper. The results show that output power is obtained only in a narrow plasma density and has a maximum value. Interaction processes among electron beam, plasma and wave are observed. The electron beam can be transported in the unmagnetized plasma for two reasons. The first, the plasma neutralized the majority of the space charge forces within the beam. The second, radial electric field generated by the electron beam interaction with the plasma leads the beam to conveqdrge along axis. As the background ion effects on the characteristics of the plasmafilled high power devices, inert gas with a high atomic number or mixed inert gases should be used in the devices?
Unmagnetized plasma filled relativistic backward wave oscillator RBWO is analyzed by particleincell(PIC) simulation in this paper. The results show that output power is obtained only in a narrow plasma density and has a maximum value. Interaction processes among electron beam, plasma and wave are observed. The electron beam can be transported in the unmagnetized plasma for two reasons. The first, the plasma neutralized the majority of the space charge forces within the beam. The second, radial electric field generated by the electron beam interaction with the plasma leads the beam to conveqdrge along axis. As the background ion effects on the characteristics of the plasmafilled high power devices, inert gas with a high atomic number or mixed inert gases should be used in the devices?
2002,
14.
Abstract:
The positron annihilation lifeti me spectrum(PALS) method was employed to study the effect of proton radiation on microstructure of the space grade KH-L-Y polysilicone rubber. The results show that both t 3, and I3 of the longest lifetime component and the free volume Vf decrease with the increase of the radiation fluence at the beginning and become level off after 1015cm- 2 radiation fluence. The proton radiation causes decrease in both the free volume of polysilicone rubber, and the distance between the molecules when the radiation fluence is less than 1015cm- 2. However, the proton radiation makes the free volume of silicon rubber increase when the radiation fluence is greater than 1015cm- 2. Both the experimental results of the cross-linking density and DMA indicate that the cross-link
The positron annihilation lifeti me spectrum(PALS) method was employed to study the effect of proton radiation on microstructure of the space grade KH-L-Y polysilicone rubber. The results show that both t 3, and I3 of the longest lifetime component and the free volume Vf decrease with the increase of the radiation fluence at the beginning and become level off after 1015cm- 2 radiation fluence. The proton radiation causes decrease in both the free volume of polysilicone rubber, and the distance between the molecules when the radiation fluence is less than 1015cm- 2. However, the proton radiation makes the free volume of silicon rubber increase when the radiation fluence is greater than 1015cm- 2. Both the experimental results of the cross-linking density and DMA indicate that the cross-link
2002,
14.
Abstract:
“Dragon-1” accelerator now is being constructed in CAEP. It will produce high current pulse electron beams. The main components of the accelerator include 72 induction accelerating cells and 18 connection cells with ports for beam diagnostic hardware and vacuum pump. In order to acquire high quality beams, a lot of problems have to be addressed such as to reduce the emittance, to control the increase of corkscrew and so on. The alignment of the focus magnetic field is the most concerned. A laser track ha s been used for mechanical alignment, magnetic alignment is performed by using pulsed-wire technique, and the natural tilt errors is corrected by a pair of steering coil, which is located inside the cell.
“Dragon-1” accelerator now is being constructed in CAEP. It will produce high current pulse electron beams. The main components of the accelerator include 72 induction accelerating cells and 18 connection cells with ports for beam diagnostic hardware and vacuum pump. In order to acquire high quality beams, a lot of problems have to be addressed such as to reduce the emittance, to control the increase of corkscrew and so on. The alignment of the focus magnetic field is the most concerned. A laser track ha s been used for mechanical alignment, magnetic alignment is performed by using pulsed-wire technique, and the natural tilt errors is corrected by a pair of steering coil, which is located inside the cell.
2002,
14.
Abstract:
One helical type of two-stage flux-trapping magnetic flux compression generators (type 8-6 MFCG) is described in this paper, by which the energy from capacity can be amplified in the first stage helix, and the power can be amplified in the second stage helix. Experiment al results show that, type 8-6 MFCG with a whole weight of about 6kg, can output pulse current up to 100kA and energy up to 20kJ on 5.25m H inductance load wit h the effective pulse duration less than 10m s.
One helical type of two-stage flux-trapping magnetic flux compression generators (type 8-6 MFCG) is described in this paper, by which the energy from capacity can be amplified in the first stage helix, and the power can be amplified in the second stage helix. Experiment al results show that, type 8-6 MFCG with a whole weight of about 6kg, can output pulse current up to 100kA and energy up to 20kJ on 5.25m H inductance load wit h the effective pulse duration less than 10m s.
2002,
14.
Abstract:
This article presents an oscillograph with both high time resolution and detection efficiency used in time-resolved neutron diagnosis in ICF (inertial confinement fusion). The oscillograph, comprising a neutron cathode, a specially designed electron optical configuration and a pair of plane deflector, is similar to a streak camera in principle except that no spatial information can be obtained. A sandwich-like polyethylene-CsI-aluminium is used to convert neutron into electron beam. The electron optics system converges the electron beam excited by neutron from a wide area at the image plane. These electrons are steered transversely by a linear voltage to obtain the intensity evolution versus time. In the experiment, a neutron generator was used to test the function and the detective effici
This article presents an oscillograph with both high time resolution and detection efficiency used in time-resolved neutron diagnosis in ICF (inertial confinement fusion). The oscillograph, comprising a neutron cathode, a specially designed electron optical configuration and a pair of plane deflector, is similar to a streak camera in principle except that no spatial information can be obtained. A sandwich-like polyethylene-CsI-aluminium is used to convert neutron into electron beam. The electron optics system converges the electron beam excited by neutron from a wide area at the image plane. These electrons are steered transversely by a linear voltage to obtain the intensity evolution versus time. In the experiment, a neutron generator was used to test the function and the detective effici
2002,
14.
Abstract:
Coler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFLCSR) belongs to China great scientific project in China. The alignment for it is very difficult because of very large area and very high accuracy. For the special case in HIRFLCSR, some new methods and new instruments are used, including the construction of survey control network, the usage of laser tracker, and CSR alignment database system with applications developed to store and analyze data. This paper describes the whole procedure of CSR alignment.
Coler Storage Ring of Heavy Ion Research Facility in Lanzhou (HIRFLCSR) belongs to China great scientific project in China. The alignment for it is very difficult because of very large area and very high accuracy. For the special case in HIRFLCSR, some new methods and new instruments are used, including the construction of survey control network, the usage of laser tracker, and CSR alignment database system with applications developed to store and analyze data. This paper describes the whole procedure of CSR alignment.
2002,
14.
Abstract:
To measure the amount of pulse fission neutrons, we carried out the theoretical research of a new method. This paper introduces its principle of measuring pulse fission neutrons, states a new detection system for measuring the neutrons with a radiation attenuator and carried 6Li plastic scintillation detector, and method of neutron sensitivity compensation, that can adapt the measurement need. And this paper gives the simulating calculation results of the system parameters. In the conclusion, it analyses the merits and the potential application of this method.
To measure the amount of pulse fission neutrons, we carried out the theoretical research of a new method. This paper introduces its principle of measuring pulse fission neutrons, states a new detection system for measuring the neutrons with a radiation attenuator and carried 6Li plastic scintillation detector, and method of neutron sensitivity compensation, that can adapt the measurement need. And this paper gives the simulating calculation results of the system parameters. In the conclusion, it analyses the merits and the potential application of this method.
2002,
14.
Abstract:
The switch rate of thyratron is related to the triggering signal. The fast thyristor is usually used in the trigger circuit, but the triggering signal is not ideal. This paper brings forward a new method of substituting power MOSFET whose switch time is shorter for thyristor in developing the pulsed fast discharge power supply of sulfur dimmer. The Experiment results prove that it can greatly improve the conduction characteristic of thyratron HY3202.
The switch rate of thyratron is related to the triggering signal. The fast thyristor is usually used in the trigger circuit, but the triggering signal is not ideal. This paper brings forward a new method of substituting power MOSFET whose switch time is shorter for thyristor in developing the pulsed fast discharge power supply of sulfur dimmer. The Experiment results prove that it can greatly improve the conduction characteristic of thyratron HY3202.
2002,
14.
Abstract:
This paper presents the theoretical evaluation for the laser scattering from the waved seawater surface with the random facet model and the depolarization property of the seawater surface. The numerical results show that the scattering light is partly depolarized in all direction except the backward. If the local incident angle equals to the Browser angle, t he scattering light will be linearly polarized for any incident laser. A simulating experiment was done to verify the theoretical analysis, and the result agrees well with the calculating one.
This paper presents the theoretical evaluation for the laser scattering from the waved seawater surface with the random facet model and the depolarization property of the seawater surface. The numerical results show that the scattering light is partly depolarized in all direction except the backward. If the local incident angle equals to the Browser angle, t he scattering light will be linearly polarized for any incident laser. A simulating experiment was done to verify the theoretical analysis, and the result agrees well with the calculating one.
2002,
14.
Abstract:
Intense pulse X-ray is used to irradiate Si-SiO2 interface. Density of Si-SiO2 interface states and its annealing process are measured. Experiment results show that radiation-induced interface traps in Si-SiO2 are increased with dose of intense pulse X-ray. A distribution that density of Si-SiO2 interface states vs. radiation dose is summarized. According to this distribution, radiation impairment effects and mechanism are discussed. Intense pulse X-ray radiation appear following characteristics: (1) Interface states induced by intense radiation are easily saturated. This saturation phenomenon is different from that of common dose radiation. (2) Annealing process shows that the more radiation-induced interface states, the more rapid eliminate these states in annealing process. (3) There ex
Intense pulse X-ray is used to irradiate Si-SiO2 interface. Density of Si-SiO2 interface states and its annealing process are measured. Experiment results show that radiation-induced interface traps in Si-SiO2 are increased with dose of intense pulse X-ray. A distribution that density of Si-SiO2 interface states vs. radiation dose is summarized. According to this distribution, radiation impairment effects and mechanism are discussed. Intense pulse X-ray radiation appear following characteristics: (1) Interface states induced by intense radiation are easily saturated. This saturation phenomenon is different from that of common dose radiation. (2) Annealing process shows that the more radiation-induced interface states, the more rapid eliminate these states in annealing process. (3) There ex
2002,
14.
Abstract:
The effects of signalinduced background (SIB) of image intensifier on low-level-light target detection are analyzed. The results show that SIB is a signal dependent noise, and presents shot noise characteristics. It can't beeliminated by background removal using environment shielding or the threshold means. The SIB is harmful to centroid detecting of low-level-light target. A new method of centroid calculation is given to reduce SIB influence effectively.
The effects of signalinduced background (SIB) of image intensifier on low-level-light target detection are analyzed. The results show that SIB is a signal dependent noise, and presents shot noise characteristics. It can't beeliminated by background removal using environment shielding or the threshold means. The SIB is harmful to centroid detecting of low-level-light target. A new method of centroid calculation is given to reduce SIB influence effectively.
2002,
14.
Abstract:
In Chemical Oxygen-Iodine Laser (COIL) system, the water vapor produced from the generator of singlet oxygen can have severe negative effects on the output of the laser power. In this paper, the water vapor content in the counter-flow Jet type Singlet Oxygen Generator (JSOG) is simulated. The results agree well with those of experiments. By way of simulation, some of the experimental conditions for JSOG are optimized to reduce the water vapor content.
In Chemical Oxygen-Iodine Laser (COIL) system, the water vapor produced from the generator of singlet oxygen can have severe negative effects on the output of the laser power. In this paper, the water vapor content in the counter-flow Jet type Singlet Oxygen Generator (JSOG) is simulated. The results agree well with those of experiments. By way of simulation, some of the experimental conditions for JSOG are optimized to reduce the water vapor content.
2002,
14.
Abstract:
Based on the phenomenological theory of semiconductors and two-level model, according to the principle of cascading nonlinear system and by analyzing the Lyapunov exponents of its dynamics equations，the chaos disturbance mechanisms of extrinsic photoconductors are surveyed and demonstrated when chaotic laser irradiated. The numerical results have shown that chaotic laser can make the extrinsic photoconductors to chaos.
Based on the phenomenological theory of semiconductors and two-level model, according to the principle of cascading nonlinear system and by analyzing the Lyapunov exponents of its dynamics equations，the chaos disturbance mechanisms of extrinsic photoconductors are surveyed and demonstrated when chaotic laser irradiated. The numerical results have shown that chaotic laser can make the extrinsic photoconductors to chaos.
2002,
14.
Abstract:
During the phase II project of NSRL, in order to monitor the injecting effectiveness, damping rate and b oscillation after update of injection and RF system, a turn-by-turn system of HLS has been proposed for storage ring diagnostics. The system employs a log-ratio electronics circuit to characterize machine properties of the updated HLS storage ring. Since the system is based on synchronous process with HLS RF (204MHz) and logarithmically demodulation, that is the electronics working at bunch pas s frequency, so reduce the complexity of signal procession chain and make it easy to implement. On the other hand, the highlighted features of the log-ratio technique such as low noise, high bandwidth and wide dynamic range, as well as response linearity are superior compared with the familiar Di
During the phase II project of NSRL, in order to monitor the injecting effectiveness, damping rate and b oscillation after update of injection and RF system, a turn-by-turn system of HLS has been proposed for storage ring diagnostics. The system employs a log-ratio electronics circuit to characterize machine properties of the updated HLS storage ring. Since the system is based on synchronous process with HLS RF (204MHz) and logarithmically demodulation, that is the electronics working at bunch pas s frequency, so reduce the complexity of signal procession chain and make it easy to implement. On the other hand, the highlighted features of the log-ratio technique such as low noise, high bandwidth and wide dynamic range, as well as response linearity are superior compared with the familiar Di
2002,
14.
Abstract:
The statistics of the fractal dimension of the intensity image and the number of phase branch points in the light field of a collimated laser beam propagating through a turbulent atmosphere are evaluated for a series of numerically-generated field and intensity patterns. Some results are summarized as follows. The fractal dimension and the number of phase branch points increase with the fluctuation condition. The fractal dimension has definite relation with the pattern sharpness, but there is no relation between the number of phase branch points and the sharpness. In the situation considered here, no saturation phenomenon is found for the fractal dimension, and the number of phase branch points has a probability distribution instead of a definite value under a certain fluctuation condition
The statistics of the fractal dimension of the intensity image and the number of phase branch points in the light field of a collimated laser beam propagating through a turbulent atmosphere are evaluated for a series of numerically-generated field and intensity patterns. Some results are summarized as follows. The fractal dimension and the number of phase branch points increase with the fluctuation condition. The fractal dimension has definite relation with the pattern sharpness, but there is no relation between the number of phase branch points and the sharpness. In the situation considered here, no saturation phenomenon is found for the fractal dimension, and the number of phase branch points has a probability distribution instead of a definite value under a certain fluctuation condition
2002,
14.
Abstract:
For supersonic COIL, we deduced the rate equation (RE) model that can deal with the cases of homogenous and inhomogenous broadening being of equal importance and the case of inhomogenous broadening effect being predominating in this paper. The effects of temperature, pressure, iodine density and frequency-shift factor on the power and efficiency of COIL are given.
For supersonic COIL, we deduced the rate equation (RE) model that can deal with the cases of homogenous and inhomogenous broadening being of equal importance and the case of inhomogenous broadening effect being predominating in this paper. The effects of temperature, pressure, iodine density and frequency-shift factor on the power and efficiency of COIL are given.
2002,
14.
Abstract:
Theoretical analysis and detailed numerical simulation on optical parametric chirped pulse amplification(OPCPA) are presented in this paper. We obtain the character of optical gain and saturation amplification under different conditions of pumping beam and signal beam. Also a design example of OPCPA and it’s calculated result are given.
Theoretical analysis and detailed numerical simulation on optical parametric chirped pulse amplification(OPCPA) are presented in this paper. We obtain the character of optical gain and saturation amplification under different conditions of pumping beam and signal beam. Also a design example of OPCPA and it’s calculated result are given.
2002,
14.
Abstract:
This paper studies the optical quality such as the peak value (PV) of wavefront error, rms and strehl ratio (RS) of the free-vortex aerodynamic window(FADW) designed for the high energy lasers using the Hartmann-Shack sensing under different inlet total pressures experimentally. The results show that the effects on the output laser wavefront of the FADW are mainly the beam deflexion and the beam divergence, the other high-level wavefront errors are very low. And the FADW can meet our needs. The Hartmann-Shack sensing can be used to measure the 2-dimensional disturbed wavefront through the FADW dynamically and it can be used to launch and correct the high energy laser out of the FADW.
This paper studies the optical quality such as the peak value (PV) of wavefront error, rms and strehl ratio (RS) of the free-vortex aerodynamic window(FADW) designed for the high energy lasers using the Hartmann-Shack sensing under different inlet total pressures experimentally. The results show that the effects on the output laser wavefront of the FADW are mainly the beam deflexion and the beam divergence, the other high-level wavefront errors are very low. And the FADW can meet our needs. The Hartmann-Shack sensing can be used to measure the 2-dimensional disturbed wavefront through the FADW dynamically and it can be used to launch and correct the high energy laser out of the FADW.
2002,
14.
Abstract:
In this paper, the expression for axial intensity distribution of Laguerre-Gaussian beams passing through an aperture-lens separation system is derived using Collins formula. It is shown that aperture-lens separation affects the focal shift and intensity distribution. T he focal shift may be reversed or eliminated. Furthermore, under certain conditions, the intensity in a large axial range is close to the maximum intensity. Thus a large range of maximum intensity can be obtained.
In this paper, the expression for axial intensity distribution of Laguerre-Gaussian beams passing through an aperture-lens separation system is derived using Collins formula. It is shown that aperture-lens separation affects the focal shift and intensity distribution. T he focal shift may be reversed or eliminated. Furthermore, under certain conditions, the intensity in a large axial range is close to the maximum intensity. Thus a large range of maximum intensity can be obtained.
2002,
14.
Abstract:
A set of coupled nonlinear threedimension differential equations for the FEM amplifier with elliptical waveguide and planar wiggler is derived. Based on these equations, a universal numerical simulation program is developed independently. The characteristics of this FEM including the evolution of power, saturation efficiency and bandwidth are investigated using the numerical method. Electron momentum spread ,spacecharge and wiggler taper are also considered. Electron beam is modeled to adiabatically inject by allowing the wiggler amplitude to increase from zero to a constant amplitude and the spacecharge is analyzed in terms of GT mode expansion method. The results show that saturated output power is 360kW, efficiency is up to 9.2% using wiggler taper and 3dB bandwidth is 6.9% of
A set of coupled nonlinear threedimension differential equations for the FEM amplifier with elliptical waveguide and planar wiggler is derived. Based on these equations, a universal numerical simulation program is developed independently. The characteristics of this FEM including the evolution of power, saturation efficiency and bandwidth are investigated using the numerical method. Electron momentum spread ,spacecharge and wiggler taper are also considered. Electron beam is modeled to adiabatically inject by allowing the wiggler amplitude to increase from zero to a constant amplitude and the spacecharge is analyzed in terms of GT mode expansion method. The results show that saturated output power is 360kW, efficiency is up to 9.2% using wiggler taper and 3dB bandwidth is 6.9% of
2002,
14.
Abstract:
This paper presents the principle, structure and aberration-corrected designing of a flat focal field concave grating spectrograph. We designed and constructed a spectrograph instrument using varied spaced concave grating with 2 400 grooves/mm. Spectral range of detection is 1.5～10nm. Typical soft X-ray line spectra emitted from laser plasma of C5H16O6 target has been obtained with this spectrograph instrument on 'Xing-guang II' laser facility. The experiment results indicate that the spectral resolution is 0.02nm. Absorption spectrum of laser-produced plasma has been observed successfully with the device.
This paper presents the principle, structure and aberration-corrected designing of a flat focal field concave grating spectrograph. We designed and constructed a spectrograph instrument using varied spaced concave grating with 2 400 grooves/mm. Spectral range of detection is 1.5～10nm. Typical soft X-ray line spectra emitted from laser plasma of C5H16O6 target has been obtained with this spectrograph instrument on 'Xing-guang II' laser facility. The experiment results indicate that the spectral resolution is 0.02nm. Absorption spectrum of laser-produced plasma has been observed successfully with the device.
2002,
14.
Abstract:
On the base of analyzing the thermal lensing effect caused by the temperature-gradient in direction of unpolished-face, a new type construction consisted of absorbing glass, insulative glass and heat sink has been designed for adiabatic structure of slab, and the experiment of thermal focal length of slab has been done. The result proves that the thermal lensing effect of slab has been improved due to adopt adiabatic construction. The focal length of 1.93m in direction of unpolished-face has been measured from the slab with adiabatic construction at 500Hz, comparing with 0.78m measured from the slab without adiabatic construction.
On the base of analyzing the thermal lensing effect caused by the temperature-gradient in direction of unpolished-face, a new type construction consisted of absorbing glass, insulative glass and heat sink has been designed for adiabatic structure of slab, and the experiment of thermal focal length of slab has been done. The result proves that the thermal lensing effect of slab has been improved due to adopt adiabatic construction. The focal length of 1.93m in direction of unpolished-face has been measured from the slab with adiabatic construction at 500Hz, comparing with 0.78m measured from the slab without adiabatic construction.
2002,
14.
Abstract:
The focusing properties of Gaussian beams through a compound optical system consisting of a concave lens, a convex lens and a subsystem, are discussed. Based on the matrix optical method, formulae of the waist width and imaging distance of focused Gaussian beams through the system are derived. It is shown that the system is capable of achieving both smaller focused waist width and larger imaging distance. The results are illustrated and confirmed with numerical calculation examples.
The focusing properties of Gaussian beams through a compound optical system consisting of a concave lens, a convex lens and a subsystem, are discussed. Based on the matrix optical method, formulae of the waist width and imaging distance of focused Gaussian beams through the system are derived. It is shown that the system is capable of achieving both smaller focused waist width and larger imaging distance. The results are illustrated and confirmed with numerical calculation examples.
2002,
14.
Abstract:
The scale length is an important parameter of the low-frequency phase aberration. The mathematics model to get t he scale lengths of the phase aberration caused by rectangular optics is established and the scale lengths of some Nd-glass amplifiers are calculated. And the characteristic values of slab-amplifiers are got. The relationship between the scale length and the spot size is studied. The change of the scale length in propagation is also analyzed.
The scale length is an important parameter of the low-frequency phase aberration. The mathematics model to get t he scale lengths of the phase aberration caused by rectangular optics is established and the scale lengths of some Nd-glass amplifiers are calculated. And the characteristic values of slab-amplifiers are got. The relationship between the scale length and the spot size is studied. The change of the scale length in propagation is also analyzed.
Longterm measurements and statistics study on refractiveindex structure parameter of surface layer
2002,
14.
Abstract:
The data of refractive index structure parameter from 1997 to 2000 at a complex terrain in Hefei are studied statistically. Results of refractive index structure parameter in different ground covers, different seasons, different heights are presented. Months goes when refractive index structure parameter in daytime from strong to weak are June, May, April, September, January. The refractive index over the grass are larger than that over the water in daytime, while the result of the comparison in nighttime is the reverse. The refractive index decreases with altitude increase both in day and at night. The refractive index structure parameter falls slower from 3 to 10m than 10 to 15m. refractive index measured and modeled agree well with each other.
The data of refractive index structure parameter from 1997 to 2000 at a complex terrain in Hefei are studied statistically. Results of refractive index structure parameter in different ground covers, different seasons, different heights are presented. Months goes when refractive index structure parameter in daytime from strong to weak are June, May, April, September, January. The refractive index over the grass are larger than that over the water in daytime, while the result of the comparison in nighttime is the reverse. The refractive index decreases with altitude increase both in day and at night. The refractive index structure parameter falls slower from 3 to 10m than 10 to 15m. refractive index measured and modeled agree well with each other.
2002,
14.
Abstract:
In this paper, starting from a comparison of two optical symmetrizing systems, a detailed analysis of the symmetrization of astigmatic Hermite-Gaussian beams and related problems is made by using the generalized HuygensFresnel diffraction integral .It is shown that the symmetrizing system plays a role in transforming astigmatic beams into symmetric beams with real argument and eliminating the xy coupling term. Thus, they can retain their shape unchanged upon further free space propagation. Nevertheless, the symmetric complex beams with the xy coupling term do not possess this propagation invariance.
In this paper, starting from a comparison of two optical symmetrizing systems, a detailed analysis of the symmetrization of astigmatic Hermite-Gaussian beams and related problems is made by using the generalized HuygensFresnel diffraction integral .It is shown that the symmetrizing system plays a role in transforming astigmatic beams into symmetric beams with real argument and eliminating the xy coupling term. Thus, they can retain their shape unchanged upon further free space propagation. Nevertheless, the symmetric complex beams with the xy coupling term do not possess this propagation invariance.
2002,
14.
Abstract:
The liquid (ethanol) wetting characteristic and dynamical mechanical property of polystyrene foams prepared by inverse emulsion with various densities have been studied. The wetting rate increases while the foam density decreases. The foams' cell sizes obtained from the relationship between the liquid wetting height and time correspond with the measured ones by SEM. The compressive modulus of the foam increases as temperature decreases and its density increases. The scaling exponent between the compressive modulus and density of PS foam is 2.02.
The liquid (ethanol) wetting characteristic and dynamical mechanical property of polystyrene foams prepared by inverse emulsion with various densities have been studied. The wetting rate increases while the foam density decreases. The foams' cell sizes obtained from the relationship between the liquid wetting height and time correspond with the measured ones by SEM. The compressive modulus of the foam increases as temperature decreases and its density increases. The scaling exponent between the compressive modulus and density of PS foam is 2.02.
2002,
14.
Abstract:
In this paper, the basic concepts, reaction equipment, experimental research, theoretical research and present applications of electron cyclotron resonance microwave plasma(ECRMP) are reviewed. At the same time, its development in the future is also discussed.
In this paper, the basic concepts, reaction equipment, experimental research, theoretical research and present applications of electron cyclotron resonance microwave plasma(ECRMP) are reviewed. At the same time, its development in the future is also discussed.
2002,
14.
Abstract:
The physical process of dielectronic recombination for Hlike, Helike and Lilike ions of Mg and Al in the medial double ionized states plays an important role in studying laser inertial confinement fusion (ICF) electronic temperature by the method of the double traced materials isoelectronic Xray spectrum. This paper presents the dielectronic recombination rate coefficients with different Rydberg configuration states channels. The rate coefficients of different ionized states are given and compared with variable temperature and transition channels．
The physical process of dielectronic recombination for Hlike, Helike and Lilike ions of Mg and Al in the medial double ionized states plays an important role in studying laser inertial confinement fusion (ICF) electronic temperature by the method of the double traced materials isoelectronic Xray spectrum. This paper presents the dielectronic recombination rate coefficients with different Rydberg configuration states channels. The rate coefficients of different ionized states are given and compared with variable temperature and transition channels．
2002,
14.
Abstract:
In this paper, the technology of network parallel computing is applied to the study of microwave tubes. The network parallel computing model based on the TCP/IP protocol is obtained, which can calculate 2.5D TWT multisignal nonlinear beam-wave interaction. And the programs simulating TWT multisignal nonlinear beam-wave interaction have been programmed, which can run on the network composed of workstations and microcomputers to realize the parallel computing. The calculating result indicates that the network parallel algorithm can save the computing time of the TWT multi-signal nonlinear beamwave interaction and improve working efficiency.
In this paper, the technology of network parallel computing is applied to the study of microwave tubes. The network parallel computing model based on the TCP/IP protocol is obtained, which can calculate 2.5D TWT multisignal nonlinear beam-wave interaction. And the programs simulating TWT multisignal nonlinear beam-wave interaction have been programmed, which can run on the network composed of workstations and microcomputers to realize the parallel computing. The calculating result indicates that the network parallel algorithm can save the computing time of the TWT multi-signal nonlinear beamwave interaction and improve working efficiency.
2002,
14.
Abstract:
The metal conductor's physical process for electric exploding is presented. The relations of the resistivity of the metal conductor versus specific action, pressure, energy density, expansion speed of explosive products, density of conductor current and dielectric etc. are analysed in the paper. The conclusion is obtained and this will provide the general design principle of electric exploding opening switch．
The metal conductor's physical process for electric exploding is presented. The relations of the resistivity of the metal conductor versus specific action, pressure, energy density, expansion speed of explosive products, density of conductor current and dielectric etc. are analysed in the paper. The conclusion is obtained and this will provide the general design principle of electric exploding opening switch．
