Email alert
RSS2006 Vol. 18, No. 05
Recommend Articles
Display Method:
2006,
18.
Abstract:
A new style boundary scoop pumping diffuser was development. The essential performance had been achieved by testing through changing boundary layer ejector pumping capacity, mixing chamber clapboard length, the counterpressure, main inlet mass flux and so on. The results prove this diffuser could effectively isolate laser cavity flow field, improving wall pressure distribution. And may be attention, the diffuser length could be cut 25%, compared to the common.
A new style boundary scoop pumping diffuser was development. The essential performance had been achieved by testing through changing boundary layer ejector pumping capacity, mixing chamber clapboard length, the counterpressure, main inlet mass flux and so on. The results prove this diffuser could effectively isolate laser cavity flow field, improving wall pressure distribution. And may be attention, the diffuser length could be cut 25%, compared to the common.
2006,
18.
Abstract:
A DC discharge method is introduced to improve the production of F atom for all gas-phase iodine laser(AGIL). Characteristics of the DC discharge are studied for the usage of cylinder electrode. About 3 kW input power is obtained when dissociating the mixture of NF3 in He by different balance resistance. Production of F atom is measured with spectrometer(CCD) and the production of F atom is about 1.3~1.5 with one NF3 molecule.
A DC discharge method is introduced to improve the production of F atom for all gas-phase iodine laser(AGIL). Characteristics of the DC discharge are studied for the usage of cylinder electrode. About 3 kW input power is obtained when dissociating the mixture of NF3 in He by different balance resistance. Production of F atom is measured with spectrometer(CCD) and the production of F atom is about 1.3~1.5 with one NF3 molecule.
2006,
18.
Abstract:
Annular subaperture test method has been developed for low cost and flexible measurement of large, fast aspheric surfaces without any special elements. The measurement principle of this method is simply introduced. The two representative algorithms based on discrete phase values and Zernike polynomials are numerically analyzed, and the result of primary experiment is provided. The results show that the method is feasible and provided that the potential for testing large aspheric mirror. According to the integrative analysis of the above research results, the experimental scheme of testing meterclass aspheric mirror with annular subaperture method is presented．
Annular subaperture test method has been developed for low cost and flexible measurement of large, fast aspheric surfaces without any special elements. The measurement principle of this method is simply introduced. The two representative algorithms based on discrete phase values and Zernike polynomials are numerically analyzed, and the result of primary experiment is provided. The results show that the method is feasible and provided that the potential for testing large aspheric mirror. According to the integrative analysis of the above research results, the experimental scheme of testing meterclass aspheric mirror with annular subaperture method is presented．
2006,
18.
Abstract:
The disturbance imposed to the stream will grow on the surface of the stream as the stream flows downward. The growth of the disturbance continues until a fluid parcel is pinched off. The fastest growth rate is related to the controllable parameters such as the speed of the jet and the frequency of the disturbance. This paper presents an experimental and analytical study to examine the breakup of a round jet into a droplet stream. The range of the speed of the jet and the frequency of the disturbance in the uniform droplet singlet oxygen generator were acquired.
The disturbance imposed to the stream will grow on the surface of the stream as the stream flows downward. The growth of the disturbance continues until a fluid parcel is pinched off. The fastest growth rate is related to the controllable parameters such as the speed of the jet and the frequency of the disturbance. This paper presents an experimental and analytical study to examine the breakup of a round jet into a droplet stream. The range of the speed of the jet and the frequency of the disturbance in the uniform droplet singlet oxygen generator were acquired.
2006,
18.
Abstract:
In order to analyze the effect of aberration of amplitude and phase of laser beam on centroid position of focal spot, based on the Fraunhofer formula for light wave scaler diffraction theory, according to the definition of first order moment centroid position, the general expression of focal spot centroid position directly depending on the complex amplitude of near field is derived. The centroid position of the focal spot diretly depending on intensity distribution and phase slope distribution of near field is derived, and its physical meaning is described. The excursion of centroid position of focal spot may be easily acquired with the centroid position expression of focal spot. At last the laser beam with simple aberration, such as no phase aberration and low order Zernike phase aberrati
In order to analyze the effect of aberration of amplitude and phase of laser beam on centroid position of focal spot, based on the Fraunhofer formula for light wave scaler diffraction theory, according to the definition of first order moment centroid position, the general expression of focal spot centroid position directly depending on the complex amplitude of near field is derived. The centroid position of the focal spot diretly depending on intensity distribution and phase slope distribution of near field is derived, and its physical meaning is described. The excursion of centroid position of focal spot may be easily acquired with the centroid position expression of focal spot. At last the laser beam with simple aberration, such as no phase aberration and low order Zernike phase aberrati
2006,
18.
Abstract:
Effect of the measurement errors of atmospheric parameters on the laser propagation effects(the average power density) was numerically analyzed. Based upon the characteristic laser propagation conditions, the demand of measurement precision of atmospheric parameters was obtained. The measurement errors of atmospheric wind velocity, absorption coefficient and the refractive index structure constant have relatively distinct effects on the laser propagation effects. Numerical analysis shows that the demands of measurement precision of these three atmospheric parameters are ±10%,±5% and ±15%, respectively.
Effect of the measurement errors of atmospheric parameters on the laser propagation effects(the average power density) was numerically analyzed. Based upon the characteristic laser propagation conditions, the demand of measurement precision of atmospheric parameters was obtained. The measurement errors of atmospheric wind velocity, absorption coefficient and the refractive index structure constant have relatively distinct effects on the laser propagation effects. Numerical analysis shows that the demands of measurement precision of these three atmospheric parameters are ±10%,±5% and ±15%, respectively.
2006,
18.
Abstract:
The phase transition principle of VO2 thin films is introduced in this paper. The X-ray diffraction pattern and spectral transmission at different temperature of vanadium dioxide thin films deposited on glass by RF magnetron sputtering were measured. Temperature and transmission change caused by heating-induced phase transition of the vanadium dioxide thin films were measured on real time under the irradiation of a 1.319 μm continuous wave laser beam with an average power density of 283 W/cm2 and a spot diameter of 2 mm. The experimental results indicate that after 480 ms laser irradiation, the temperature of vanadium dioxide thin film is raised from room temperature to about 100 ℃, phase transition occurs and transmittance decreases from 48% before the phase transition to 28% after the
The phase transition principle of VO2 thin films is introduced in this paper. The X-ray diffraction pattern and spectral transmission at different temperature of vanadium dioxide thin films deposited on glass by RF magnetron sputtering were measured. Temperature and transmission change caused by heating-induced phase transition of the vanadium dioxide thin films were measured on real time under the irradiation of a 1.319 μm continuous wave laser beam with an average power density of 283 W/cm2 and a spot diameter of 2 mm. The experimental results indicate that after 480 ms laser irradiation, the temperature of vanadium dioxide thin film is raised from room temperature to about 100 ℃, phase transition occurs and transmittance decreases from 48% before the phase transition to 28% after the
2006,
18.
Abstract:
A simple engineering method is developed to design and predict the performance of the constant-mixing ejector. The influence of ejector parameters on performance is also analyzed. Since the method is formulated in terms of enthalpy, it is applicable to all kinds of primary and secondary gases. In order to control ejector size, the multi-nozzle type and the constant-mixing ejector are integrated. For purpose of verification, the method is compared with experiment results.
A simple engineering method is developed to design and predict the performance of the constant-mixing ejector. The influence of ejector parameters on performance is also analyzed. Since the method is formulated in terms of enthalpy, it is applicable to all kinds of primary and secondary gases. In order to control ejector size, the multi-nozzle type and the constant-mixing ejector are integrated. For purpose of verification, the method is compared with experiment results.
2006,
18.
Abstract:
The mechanism of ejecting gas-shades of COIL was given. The effect of ejecting gas-shades on pressures and output power of COIL was studied. The result shows that by adopting the action modes of ejecting gas-shades in the optical resonator, the loss of stagnation pressure is remarkably reduced. The working load of the pressure recover system at COIL exit will be lightened. On high back-pressure condition, static pressure in the resonator is remarkably reduced then the stability of static pressure in the resonator is improved.
The mechanism of ejecting gas-shades of COIL was given. The effect of ejecting gas-shades on pressures and output power of COIL was studied. The result shows that by adopting the action modes of ejecting gas-shades in the optical resonator, the loss of stagnation pressure is remarkably reduced. The working load of the pressure recover system at COIL exit will be lightened. On high back-pressure condition, static pressure in the resonator is remarkably reduced then the stability of static pressure in the resonator is improved.
2006,
18.
Abstract:
Measurement principle of ingredient and concentration of matter with difference absorption lidar (DIAL) is introduced. The distribution of NO2 concentration within 3.5 km range is measured with the DIAL. The result shows that very accurate concentration distance distribution of NO2 can be acquired by use of two wavelength (448.2 nm and 446.8 nm) of wavelength tunable Ti:sapphire laser ．
Measurement principle of ingredient and concentration of matter with difference absorption lidar (DIAL) is introduced. The distribution of NO2 concentration within 3.5 km range is measured with the DIAL. The result shows that very accurate concentration distance distribution of NO2 can be acquired by use of two wavelength (448.2 nm and 446.8 nm) of wavelength tunable Ti:sapphire laser ．
2006,
18.
Abstract:
An efficient VertiCOIL with a square pipe-array jet-type singlet oxygen generator and without primary buffer gas was demonstrated in our laboratory. The most important motivation for no primary buffer gas is that it easily enables the use of a cryosorption pump as the vacuum pumping system, besides, it can greatly reduce the cost and volume of COIL systems for industrial applications. A nozzle bank, with a gain length of 11.7 cm, a subsonic iodine-oxygen mixing length of 4 mm and a designed Mach number of 2.5, is energized by a specially designed SPJSOG operating with no buffer gas. As a result of optimization of the SOG parameters, a maximum output power exceeding 2.25 kW with chemical efficiency of 21.1%, a nozzle exit flux of 64 W/cm2 and a specific power of 0.22 J/g were obtained for a
An efficient VertiCOIL with a square pipe-array jet-type singlet oxygen generator and without primary buffer gas was demonstrated in our laboratory. The most important motivation for no primary buffer gas is that it easily enables the use of a cryosorption pump as the vacuum pumping system, besides, it can greatly reduce the cost and volume of COIL systems for industrial applications. A nozzle bank, with a gain length of 11.7 cm, a subsonic iodine-oxygen mixing length of 4 mm and a designed Mach number of 2.5, is energized by a specially designed SPJSOG operating with no buffer gas. As a result of optimization of the SOG parameters, a maximum output power exceeding 2.25 kW with chemical efficiency of 21.1%, a nozzle exit flux of 64 W/cm2 and a specific power of 0.22 J/g were obtained for a
2006,
18.
Abstract:
VICON code was used to simulate COIL cold flowfields, and the obtained geometry nicely reflected the geometry change of the simulated equipment. The grid dimensions of primary and secondary flow reflected gas characteristics of the two dimension plane. The simulation results of different flux showed that excess or insufficient penetration led bad mixing. Changing process of horseshoe that secondary flow came out from orifice and entered primary flow was showed by simulation of chemical reaction. Those show that the VICON code may be used to study flowfield properties on COIL nozzle.
VICON code was used to simulate COIL cold flowfields, and the obtained geometry nicely reflected the geometry change of the simulated equipment. The grid dimensions of primary and secondary flow reflected gas characteristics of the two dimension plane. The simulation results of different flux showed that excess or insufficient penetration led bad mixing. Changing process of horseshoe that secondary flow came out from orifice and entered primary flow was showed by simulation of chemical reaction. Those show that the VICON code may be used to study flowfield properties on COIL nozzle.
2006,
18.
Abstract:
The receiving efficiency is alternately varying with the azimuth or elevation of the telescope when laser guide star(LGS) is launched and received in a common aperture of altazimuth coude telescope with polarizing beam splitting scheme, because of the phase difference between the s and p polarizing vector caused by the film on the reflecting mirrors. The phase compensation technology of polarizing beam is researched. A phase compensator made of a quarter waveplate and a Faraday rotator is presented. This copensator can keep the efficiency from degrading by rotating the quarter waveplate. Numerical calculation shows that the received efficiency with effective compensation on the quarter waveplate rotating step 1° could be more than 99.90%. A principle experiment confirms that the rotating
The receiving efficiency is alternately varying with the azimuth or elevation of the telescope when laser guide star(LGS) is launched and received in a common aperture of altazimuth coude telescope with polarizing beam splitting scheme, because of the phase difference between the s and p polarizing vector caused by the film on the reflecting mirrors. The phase compensation technology of polarizing beam is researched. A phase compensator made of a quarter waveplate and a Faraday rotator is presented. This copensator can keep the efficiency from degrading by rotating the quarter waveplate. Numerical calculation shows that the received efficiency with effective compensation on the quarter waveplate rotating step 1° could be more than 99.90%. A principle experiment confirms that the rotating
2006,
18.
Abstract:
It is necessary to measure the phase difference between s wave and p wave caused by the telescope for the dynamic phase compensation of the polarizing beam splitting system of laser launched and received in common aperture. A physical model is built up by using the Mueller matrix and the Stokes vector. Based on the model, the relationship between the phase difference and the measured laser power is obtained. An experimental method is presented to calculate the phase difference of plane mirror through the measured laser power, and the way to determine the only correct value between 0～2p is figured out. The phase difference of two mirrors is measured, and the results have been applied to the polarizing beam splitting experiment with dynamic phase compensation which verifies the correctness
It is necessary to measure the phase difference between s wave and p wave caused by the telescope for the dynamic phase compensation of the polarizing beam splitting system of laser launched and received in common aperture. A physical model is built up by using the Mueller matrix and the Stokes vector. Based on the model, the relationship between the phase difference and the measured laser power is obtained. An experimental method is presented to calculate the phase difference of plane mirror through the measured laser power, and the way to determine the only correct value between 0～2p is figured out. The phase difference of two mirrors is measured, and the results have been applied to the polarizing beam splitting experiment with dynamic phase compensation which verifies the correctness
2006,
18.
Abstract:
In adaptive optic system, for correcting the atmosphere turbulence, base on the open-loop atmospheric data, a kind of prediction control algorithm was proposed in this paper to reduce the effect of servo lag. The spatio-temporal recursive least square (RLS) prediction algorithm was used to predict the deformable mirror. The residual error of the adaptive optics system was calculated with and without the prediction control algorithm respectively. The results show that the residual error was reduced effectively with the RLS algorithm.
In adaptive optic system, for correcting the atmosphere turbulence, base on the open-loop atmospheric data, a kind of prediction control algorithm was proposed in this paper to reduce the effect of servo lag. The spatio-temporal recursive least square (RLS) prediction algorithm was used to predict the deformable mirror. The residual error of the adaptive optics system was calculated with and without the prediction control algorithm respectively. The results show that the residual error was reduced effectively with the RLS algorithm.
2006,
18.
Abstract:
Scheme and laboratory demonstration test of composite axes inertial line of sight stabilization of acquisition, tracking and pointing system on moving base are introduced. Inertial angular rate measured by dynamically tuned gyroscope is used to realize bed coarse stabilization in big range and inertial angular position measured by linear accelerometers is used to realize line of sight reference fine stabilization in small range. The coarse stabilization error is composed with line of sight reference stabilization error and the relative error between line of sight reference and its base. Test results show that an arcsecond stabilization accuracy can be acquired with composite axes stabilization scheme．
Scheme and laboratory demonstration test of composite axes inertial line of sight stabilization of acquisition, tracking and pointing system on moving base are introduced. Inertial angular rate measured by dynamically tuned gyroscope is used to realize bed coarse stabilization in big range and inertial angular position measured by linear accelerometers is used to realize line of sight reference fine stabilization in small range. The coarse stabilization error is composed with line of sight reference stabilization error and the relative error between line of sight reference and its base. Test results show that an arcsecond stabilization accuracy can be acquired with composite axes stabilization scheme．
2006,
18.
Abstract:
Visual simulation offers the scientific researchers the means of discovering the laws of nature by 3D space. A distributed interactive simulation system of lidar based on LAN is exploited to examine the moving target being tracked and aimed. Visual simulation system of moving target being tracked process is the key of this system. 3D graphics software is introduced and compared with Vega, a popular visual simulation software. The realization of the most important parts of the visual simulation system of target being tracked is described.
Visual simulation offers the scientific researchers the means of discovering the laws of nature by 3D space. A distributed interactive simulation system of lidar based on LAN is exploited to examine the moving target being tracked and aimed. Visual simulation system of moving target being tracked process is the key of this system. 3D graphics software is introduced and compared with Vega, a popular visual simulation software. The realization of the most important parts of the visual simulation system of target being tracked is described.
2006,
18.
Abstract:
The principle of real time measurement XeF2 concentration by absorbed spectrum and XeF2 concentration control means in laser chamber are introduced. Relation of XeF2 concentration between laser chamber and measure cell is given. XeF2 concentration could be controlled by adjusting the temperature of the XeF2 generator and the flow velocity in the main and carrier gas-passages. XeF2 concentrations under different mixed gas flow are obtained.
The principle of real time measurement XeF2 concentration by absorbed spectrum and XeF2 concentration control means in laser chamber are introduced. Relation of XeF2 concentration between laser chamber and measure cell is given. XeF2 concentration could be controlled by adjusting the temperature of the XeF2 generator and the flow velocity in the main and carrier gas-passages. XeF2 concentrations under different mixed gas flow are obtained.
2006,
18.
Abstract:
Adopting the echelon-free induced spatial incoherence (EFISI) technique and image relay technique, a new angular multiplexing with smoothing function was built. The total energy of 6 beams is 158 J, the stability of energy is 4%, the pulse duration is 25 ns, the effective diameter of focusing spot is 400 μm, the ununiformity is about 1.6%, and the power density on the target is about 3.7×1012 W/cm2.
Adopting the echelon-free induced spatial incoherence (EFISI) technique and image relay technique, a new angular multiplexing with smoothing function was built. The total energy of 6 beams is 158 J, the stability of energy is 4%, the pulse duration is 25 ns, the effective diameter of focusing spot is 400 μm, the ununiformity is about 1.6%, and the power density on the target is about 3.7×1012 W/cm2.
2006,
18.
Abstract:
In this paper, a diagnostic method of average ionization degree by X-ray emission spectra of laser-produced gold plasma was presented. The coupled equations between the total intensities of 5f-3d transition arrays of gold M-band and the ion populations were set up based on steady collision-radiative equilibrium approximation, with electron-ion collisional excitation and dielectronic recombination being considered in the populations of exciting states. By the experimentally measured intensities of the 5f-3d transition arrays of gold ions, we deduced the distribution of charge states and average ionization degree of laser-produced gold plasma. Furthermore, we discussed the effects of electron temperature, electron density and dielectronic recombination on the diagnostics, and compared the di
In this paper, a diagnostic method of average ionization degree by X-ray emission spectra of laser-produced gold plasma was presented. The coupled equations between the total intensities of 5f-3d transition arrays of gold M-band and the ion populations were set up based on steady collision-radiative equilibrium approximation, with electron-ion collisional excitation and dielectronic recombination being considered in the populations of exciting states. By the experimentally measured intensities of the 5f-3d transition arrays of gold ions, we deduced the distribution of charge states and average ionization degree of laser-produced gold plasma. Furthermore, we discussed the effects of electron temperature, electron density and dielectronic recombination on the diagnostics, and compared the di
2006,
18.
Abstract:
The soft X-ray Mach-Zehnder interferometer is an important tool in measuring the electron densities of laser-produced plasma near the critical surface. The design, fabrication and characterization of multilayer beam splitters at 13.9 nm for soft X-ray Mach-Zehnder interferometer are presented in the paper. The design of beam splitter is completed based on the standard of maximizing product of reflectivity and transmission of the beam splitter at 13.9 nm. The beam splitters, which are Mo/Si multilayer deposited on 10 mm×10 mm area, 100 nm thickness Si3N4 membranes, are fabricated using the magnetron sputtering. A method based on extended He-Ne laser beam is developed to analyze the figure error of the beam splitters. The data measured by an optical profiler prove that the method based on v
The soft X-ray Mach-Zehnder interferometer is an important tool in measuring the electron densities of laser-produced plasma near the critical surface. The design, fabrication and characterization of multilayer beam splitters at 13.9 nm for soft X-ray Mach-Zehnder interferometer are presented in the paper. The design of beam splitter is completed based on the standard of maximizing product of reflectivity and transmission of the beam splitter at 13.9 nm. The beam splitters, which are Mo/Si multilayer deposited on 10 mm×10 mm area, 100 nm thickness Si3N4 membranes, are fabricated using the magnetron sputtering. A method based on extended He-Ne laser beam is developed to analyze the figure error of the beam splitters. The data measured by an optical profiler prove that the method based on v
2006,
18.
Abstract:
By supposing the ion sphere model, the self-consistent field method between the Poisson-Boltzmann equation and the Dirac equation is used to calculate the energy levels of H-like neon immersed in hot and dense plasmas. Consequently, the effects of the plasma on the bound energy levels, and on the transitions between 1s and 2p electron configurations are studied. The results show that the spectral line shift increases with the increase of electron density, and decreases with the increase of electron temperature. The discrepancy of the fine spectral splitting decreases with the increase of electron density, and increases with the increase of electron temperature. All the variations will not only seriously affect the final spectrum simulations, but also make it possible to experimentally obse
By supposing the ion sphere model, the self-consistent field method between the Poisson-Boltzmann equation and the Dirac equation is used to calculate the energy levels of H-like neon immersed in hot and dense plasmas. Consequently, the effects of the plasma on the bound energy levels, and on the transitions between 1s and 2p electron configurations are studied. The results show that the spectral line shift increases with the increase of electron density, and decreases with the increase of electron temperature. The discrepancy of the fine spectral splitting decreases with the increase of electron density, and increases with the increase of electron temperature. All the variations will not only seriously affect the final spectrum simulations, but also make it possible to experimentally obse
2006,
18.
Abstract:
An optically recording velocity interferometer system(ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called “Heaven Ⅰ” with laser wavelength of 248.4 nm, pulse duation of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24×1011W·cm-2, and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intersity 7.28 ×
An optically recording velocity interferometer system(ORVIS) was developed for the free-surface velocity measurements in the equation of state experiments. The time history of free-surface velocity could be recorded by the electronic streak camera. In the experiments, ORVIS got a 179 ps time resolution, and a higher time resolution could be got by minimizing the delay time. The equation of state experiments were carried out on the high power excimer laser system called “Heaven Ⅰ” with laser wavelength of 248.4 nm, pulse duation of 25 ns and maximum energy 158 J. Free-surface velocity of 20 μm thick iron got 3.86 km/s with laser intensity of 6.24×1011W·cm-2, and free-surface velocity of 100 μm thick aluminum with 100 μm CH foil at the front got 2.87 km/s with laser intersity 7.28 ×
2006,
18.
Abstract:
To meet the requirement on the quality and the stability of the output pulse from the fiber front-end system in ICF driver, the polarization characteristics of the fiber system have been analyzed and different polarization control technologies have been researched by the experiments. For the narrow spectral width (several pm) and short pulse (several ns) of the system, considering the requirement on the time character in the final output of the system, the special average depolarization has been adopted. As a result, the complete depolarization of the light signal can be realized efficiently and the stability of the system with the depolarizer achieves 1.72% .
To meet the requirement on the quality and the stability of the output pulse from the fiber front-end system in ICF driver, the polarization characteristics of the fiber system have been analyzed and different polarization control technologies have been researched by the experiments. For the narrow spectral width (several pm) and short pulse (several ns) of the system, considering the requirement on the time character in the final output of the system, the special average depolarization has been adopted. As a result, the complete depolarization of the light signal can be realized efficiently and the stability of the system with the depolarizer achieves 1.72% .
2006,
18.
Abstract:
In 2D hydrodynamic simulation, Lagrangian mesh are prone to distort. The ALE (Arbitrary Lagrangian-Eulerian) method which combines the best features of Lagrangian and Eulerian representation was widely used to solve large distortion problems. Based on laser-target coupling, a new second order conservative remapping algorithm for physical variables utilizing mass flux was developed. In this paper, the new algorithm is applied in 1D laser-target code and has satisfactory results in practical model simulations.
In 2D hydrodynamic simulation, Lagrangian mesh are prone to distort. The ALE (Arbitrary Lagrangian-Eulerian) method which combines the best features of Lagrangian and Eulerian representation was widely used to solve large distortion problems. Based on laser-target coupling, a new second order conservative remapping algorithm for physical variables utilizing mass flux was developed. In this paper, the new algorithm is applied in 1D laser-target code and has satisfactory results in practical model simulations.
2006,
18.
Abstract:
Three sets of lens array (LA) uniform illumination system were designed, which were used in double-frequency laser direct drive experiments on “Shenguang-Ⅱ” laser facility. Experimental investigations on shock planarity were carried out. The results show that the shock planarity has strong relationship with the LA's parameters, plane target's thickness and target's position. The shock planarity driven by the LA with 121 elements is the best, and which indirectly indicates that the illumination of the 121-element LA is the most uniform, too. Moreover, with the target thickness increasing, the shock planarity becomes worse, and the planar area becomes smaller. Also, the shock planarity showes some periodical change with the target's position, and the shock planarity at focal plane is the
Three sets of lens array (LA) uniform illumination system were designed, which were used in double-frequency laser direct drive experiments on “Shenguang-Ⅱ” laser facility. Experimental investigations on shock planarity were carried out. The results show that the shock planarity has strong relationship with the LA's parameters, plane target's thickness and target's position. The shock planarity driven by the LA with 121 elements is the best, and which indirectly indicates that the illumination of the 121-element LA is the most uniform, too. Moreover, with the target thickness increasing, the shock planarity becomes worse, and the planar area becomes smaller. Also, the shock planarity showes some periodical change with the target's position, and the shock planarity at focal plane is the
2006,
18.
Abstract:
Based on theoretic analysis on experimental data, the changes of the optical absorption and Nd3+ non-radiative transition probability caused by Fe concentration in N31 glass are discussed in detail. The optical loss at 1 053 nm and Nd3+ non-radiative energy losses increase quadratically with Fe concentration below 10-4. It is found that the optical absorption loss at 1 053 nm increases rapidly with increasing Fe concentration. However, Nd3+ non-radiative energy losses are less than 50 Hz. It is an important way to improve the laser performance by decreasing Fe concentration in melting process.
Based on theoretic analysis on experimental data, the changes of the optical absorption and Nd3+ non-radiative transition probability caused by Fe concentration in N31 glass are discussed in detail. The optical loss at 1 053 nm and Nd3+ non-radiative energy losses increase quadratically with Fe concentration below 10-4. It is found that the optical absorption loss at 1 053 nm increases rapidly with increasing Fe concentration. However, Nd3+ non-radiative energy losses are less than 50 Hz. It is an important way to improve the laser performance by decreasing Fe concentration in melting process.
2006,
18.
Abstract:
Based on supercontinuum injection, a new method of high-energy femtosecond parametric amplification is put forward. The method overcomes the gain narrowing effect of the conventional 1 053 nm low-energy amplification and realizes the synchronization between 800 nm and 1 053 nm laser pulses. Through systematic experimental investigation, a broadband 1 053 nm laser pulse is obtained, with energy exceeding 4 mJ,which is the maximum energy obtained directly through a femtosecond OPA in the world.
Based on supercontinuum injection, a new method of high-energy femtosecond parametric amplification is put forward. The method overcomes the gain narrowing effect of the conventional 1 053 nm low-energy amplification and realizes the synchronization between 800 nm and 1 053 nm laser pulses. Through systematic experimental investigation, a broadband 1 053 nm laser pulse is obtained, with energy exceeding 4 mJ,which is the maximum energy obtained directly through a femtosecond OPA in the world.
2006,
18.
Abstract:
Using ultra-highly doped Yb3+ fiber as gain medium for the first time in China, pumped by 974 nm LD and passively mode-locked by nonlinear polarization rotation effect of the fiber, stable mode-locked fiber ring laser is obtained. The mode-locked threshold power of the laser is 150 mW and the output power is 26 mW with a pump power of 220 mW. The center wavelength of the mode-locked pulse is 1 046 nm with 3 dB bandwidth of 6.01 nm, 20 dB bandwidth of 16nm, pulsewidth of 22 ps and repetition rate of 20 MHz. Compared with similar fiber lasers, the laser has higher output power and better stability.
Using ultra-highly doped Yb3+ fiber as gain medium for the first time in China, pumped by 974 nm LD and passively mode-locked by nonlinear polarization rotation effect of the fiber, stable mode-locked fiber ring laser is obtained. The mode-locked threshold power of the laser is 150 mW and the output power is 26 mW with a pump power of 220 mW. The center wavelength of the mode-locked pulse is 1 046 nm with 3 dB bandwidth of 6.01 nm, 20 dB bandwidth of 16nm, pulsewidth of 22 ps and repetition rate of 20 MHz. Compared with similar fiber lasers, the laser has higher output power and better stability.
2006,
18.
Abstract:
A new approach to synthesize gold nano cluster doped aerogel on the basis of surfacecatalyzed reduction of metal ions was described in this paper. Au nano particles were formed in a silica aerogel matrix by hydroxylamine seeding method of reducing gold ions on the silica colloidal surface. Subsequently, the pH value of system was adjusted to about 7~8, the gel formed within 2 h. After aging for 2 d, the gels were washed in aceton, and then dried supercritically (from CO2) to yield aerogels. The reduction process was attributed to hydroxylamine-induced surface catalysis. Au clusters in the aerogel monoliths were characterized with optical adsorption, transmission electron microscopy. These techniques have shown the cluster size and weight content in the aerogels. Brunauer Emmett teller su
A new approach to synthesize gold nano cluster doped aerogel on the basis of surfacecatalyzed reduction of metal ions was described in this paper. Au nano particles were formed in a silica aerogel matrix by hydroxylamine seeding method of reducing gold ions on the silica colloidal surface. Subsequently, the pH value of system was adjusted to about 7~8, the gel formed within 2 h. After aging for 2 d, the gels were washed in aceton, and then dried supercritically (from CO2) to yield aerogels. The reduction process was attributed to hydroxylamine-induced surface catalysis. Au clusters in the aerogel monoliths were characterized with optical adsorption, transmission electron microscopy. These techniques have shown the cluster size and weight content in the aerogels. Brunauer Emmett teller su
2006,
18.
Abstract:
X-ray streak cameras are very important in inertial confinement fusion experiments. The characterization of the cameras should be carried out to ensure the reliability and accuracy of the experimental data. The temporal characteristics of the X-ray streak camera, such as sweep speed and temporal resolution, were calibrated for the first time on the 20 TW laser facility at High Power Laser and Physics Joint Laboratory in Shanghai. Results of the calibration experiments show that some of the specifications of the X-ray camera have changed compared with their nominal values. With these calibration data, the processing and the analysis of the ICF experimental results are turned out to be more creditable.
X-ray streak cameras are very important in inertial confinement fusion experiments. The characterization of the cameras should be carried out to ensure the reliability and accuracy of the experimental data. The temporal characteristics of the X-ray streak camera, such as sweep speed and temporal resolution, were calibrated for the first time on the 20 TW laser facility at High Power Laser and Physics Joint Laboratory in Shanghai. Results of the calibration experiments show that some of the specifications of the X-ray camera have changed compared with their nominal values. With these calibration data, the processing and the analysis of the ICF experimental results are turned out to be more creditable.
2006,
18.
Abstract:
The operating characteristics of S band frequency-agile relativistic magnetron are described. The effects of some factors, such as the anode endcap and the loaded Q value, and the breakdown at the output horn surface are discussed and analysed. The experimental results show that the peak power 1 to 1.7 GW can be generated when the frequency of the tube is adjusted in the range from 2.55 to 3.05 GHz.
The operating characteristics of S band frequency-agile relativistic magnetron are described. The effects of some factors, such as the anode endcap and the loaded Q value, and the breakdown at the output horn surface are discussed and analysed. The experimental results show that the peak power 1 to 1.7 GW can be generated when the frequency of the tube is adjusted in the range from 2.55 to 3.05 GHz.
2006,
18.
Abstract:
In this paper, a relativistic high power microwave generator with coaxial slow wave structure was experimentally researched. The experimental system was set up based on the structure optimized by numerical simulation. Preliminary results show that the generator has the advantage of high beam-wave conversion efficiency. Although the experimental system was not yet in a state of optimization, a microwave pulse with peak power of 1.3 GW and efficiency of 28% was generated. The microwave frequency is about 7.7 GHz and varies very slowly with diode voltage, which is consistent with the results of numerical simulation.
In this paper, a relativistic high power microwave generator with coaxial slow wave structure was experimentally researched. The experimental system was set up based on the structure optimized by numerical simulation. Preliminary results show that the generator has the advantage of high beam-wave conversion efficiency. Although the experimental system was not yet in a state of optimization, a microwave pulse with peak power of 1.3 GW and efficiency of 28% was generated. The microwave frequency is about 7.7 GHz and varies very slowly with diode voltage, which is consistent with the results of numerical simulation.
2006,
18.
Abstract:
An electromagnetic radiation (EMR) effect evaluation method is presented in this paper. The effect is ranked by the weighted average of the coupled electric field with domain decomposition and subdomain sensitive factors. Meanwhile, a facilitated electromagnetic model of a general purpose computer motherboard is built. Numerical simulation based on the Finite-Difference Time-Domain (FDTD) method is performed and the coupled electromagnetic field of the motherboard is achieved. EMR with incident angle from 0° to 90° at frequency from 3 GHz to 12 GHz is simulated and their effects are compared based on the developed evaluation method. Numerical results show that: (a) The larger the EMR incident angle is, the weaker the EMR effect is. The maximum weighted average of electric field is obtain
An electromagnetic radiation (EMR) effect evaluation method is presented in this paper. The effect is ranked by the weighted average of the coupled electric field with domain decomposition and subdomain sensitive factors. Meanwhile, a facilitated electromagnetic model of a general purpose computer motherboard is built. Numerical simulation based on the Finite-Difference Time-Domain (FDTD) method is performed and the coupled electromagnetic field of the motherboard is achieved. EMR with incident angle from 0° to 90° at frequency from 3 GHz to 12 GHz is simulated and their effects are compared based on the developed evaluation method. Numerical results show that: (a) The larger the EMR incident angle is, the weaker the EMR effect is. The maximum weighted average of electric field is obtain
2006,
18.
Abstract:
One-dimensional theoretical analysis is presented for the inward-emitting coaxial virtual cathode oscillator. Numerical solutions are given for the relationship of the diode voltage and current, the space-charge limited current in the coaxial drift space, and the position of the virtual cathode. Full three-dimensional numerical simulation with the PIC method is carried out using the TS3 module of the MAFIA code. The distance between the cathode emission region and anode reflector is optimized by monitoring the frequency spectrum and output power of the propagating modes in the cylindrical output waveguide. Results show that TE11 and TM01 modes between them there exists mode competition are both the dominant modes even with the axisymmetric configuration. Based on the previous optimization,
One-dimensional theoretical analysis is presented for the inward-emitting coaxial virtual cathode oscillator. Numerical solutions are given for the relationship of the diode voltage and current, the space-charge limited current in the coaxial drift space, and the position of the virtual cathode. Full three-dimensional numerical simulation with the PIC method is carried out using the TS3 module of the MAFIA code. The distance between the cathode emission region and anode reflector is optimized by monitoring the frequency spectrum and output power of the propagating modes in the cylindrical output waveguide. Results show that TE11 and TM01 modes between them there exists mode competition are both the dominant modes even with the axisymmetric configuration. Based on the previous optimization,
2006,
18.
Abstract:
Based on the theory of mode-coupling, an analysis on cold complex cavity with gradual transition is presented, in which the multiple modes coupling are taken into account. The influences of the obliquity of taper section coupling on the axial field amplitude profile and the Q value of this complex cavity are analyzed. Theoretical analysis and simulation indicate that choosing suitable obliquity can ensure good amplitude magnification which helps to improve the efficiency of beam-wave interaction.
Based on the theory of mode-coupling, an analysis on cold complex cavity with gradual transition is presented, in which the multiple modes coupling are taken into account. The influences of the obliquity of taper section coupling on the axial field amplitude profile and the Q value of this complex cavity are analyzed. Theoretical analysis and simulation indicate that choosing suitable obliquity can ensure good amplitude magnification which helps to improve the efficiency of beam-wave interaction.
2006,
18.
Abstract:
A novel back-ward wave oscillator (BWO) with photonic band gap (PBG) structure is proposed. The PBG structure offers mode-confining and choosing mechanisms, restraining the lower modes and making the BWO operate at the higher modes. With the method of numerical simulation, a single TM03-like mode is obtained at Ka band in a triangular lattice dielectric PBG structure with the medium cylinder radius 0.12 cm, the distance between the nearest rods 0.31 cm, and the permittivity 4.0. The complete dispersive characteristic of electromagnetic modes is obtained. During 36~40 GHz, the device can operate in back-wave situation with the period of 0.4 cm.
A novel back-ward wave oscillator (BWO) with photonic band gap (PBG) structure is proposed. The PBG structure offers mode-confining and choosing mechanisms, restraining the lower modes and making the BWO operate at the higher modes. With the method of numerical simulation, a single TM03-like mode is obtained at Ka band in a triangular lattice dielectric PBG structure with the medium cylinder radius 0.12 cm, the distance between the nearest rods 0.31 cm, and the permittivity 4.0. The complete dispersive characteristic of electromagnetic modes is obtained. During 36~40 GHz, the device can operate in back-wave situation with the period of 0.4 cm.
2006,
18.
Abstract:
Wistar rats were exposed to 90W/cm2 X-band HPM irradiation for 10 minutes. Myocardial tissues were collected at 0, 0.5, 1, 3, 6, 12, 24 h post exposure. The histopathological changes were observed with light microscope. The cardiomyocytes apoptosis were determined by TUNEL method. The changes of GSK-3β, caspase-9 and caspase-3 mRNA expression in rat myocardium after 90 W/cm2 HPM irradiation were determined by using RT-PCR. The changes of GSK-3β phosphorylation were determined by using western blotting. The changes of caspase-9 enzymes activity induced by HPM irradiation were assessed via a colorimetric assay utilizing specific substrates. X-band microwave irradiation can induce cardiomyocyte apoptosis. HPM also leads to obvious activation of GSK3β and coupled signal transduction pathway
Wistar rats were exposed to 90W/cm2 X-band HPM irradiation for 10 minutes. Myocardial tissues were collected at 0, 0.5, 1, 3, 6, 12, 24 h post exposure. The histopathological changes were observed with light microscope. The cardiomyocytes apoptosis were determined by TUNEL method. The changes of GSK-3β, caspase-9 and caspase-3 mRNA expression in rat myocardium after 90 W/cm2 HPM irradiation were determined by using RT-PCR. The changes of GSK-3β phosphorylation were determined by using western blotting. The changes of caspase-9 enzymes activity induced by HPM irradiation were assessed via a colorimetric assay utilizing specific substrates. X-band microwave irradiation can induce cardiomyocyte apoptosis. HPM also leads to obvious activation of GSK3β and coupled signal transduction pathway
2006,
18.
Abstract:
A novel high power microwave detector is investigated, which is based on the characteristics of thermionic diode. This kind of detector has a lot of advantages such as high power capability (up to 100 kW), fast response time(less than 2 ns), immune to the electromagnetic disturbance, etc. Additionally, it can work perfectly without synchronous signal. It can be made into the form of waveguide and coaxial detector. The waveguide detector is made up of a thermionic diode, standard waveguide, filter and external circuit, whose operating frequency is within the operating frequency range of the waveguide. And the coaxial detector is made up of a thermionic diode, coaxial line, filter and external circuit, which can work in a broad frequency range. The structure, the calibration method and resul
A novel high power microwave detector is investigated, which is based on the characteristics of thermionic diode. This kind of detector has a lot of advantages such as high power capability (up to 100 kW), fast response time(less than 2 ns), immune to the electromagnetic disturbance, etc. Additionally, it can work perfectly without synchronous signal. It can be made into the form of waveguide and coaxial detector. The waveguide detector is made up of a thermionic diode, standard waveguide, filter and external circuit, whose operating frequency is within the operating frequency range of the waveguide. And the coaxial detector is made up of a thermionic diode, coaxial line, filter and external circuit, which can work in a broad frequency range. The structure, the calibration method and resul
2006,
18.
Abstract:
Experiments are carried out to study the sensitivity and detected waveforms for two types of detectors, WB-CD01 and 2087-6001-00, with microwave signals of pulse-width varying from 20 ns to 120 ns in a step of 10 ns. At 2.7 GHz, when the pulse-width changes from 20 ns to 120 ns, the sensitivity of WB-CD01 type is 0.5~0.7dB lower than in the case of continuous wave (CW), while it is about 1dB lower than that of 2087-6001-00 type in the CW case. At 4.1 GHz, given the pulse-width of 20 ns, the sensitivity of WB-CD01 type is about 0.2 dB higher than in the CW case, while it is almost the same as the CW case for the other given pulse-width. For all the given pulse-width at 4.1 GHz, the sensitivity of 2087-6001-00 type is almost the same as in CW case. In the cases of pulsed microwaves, an overs
Experiments are carried out to study the sensitivity and detected waveforms for two types of detectors, WB-CD01 and 2087-6001-00, with microwave signals of pulse-width varying from 20 ns to 120 ns in a step of 10 ns. At 2.7 GHz, when the pulse-width changes from 20 ns to 120 ns, the sensitivity of WB-CD01 type is 0.5~0.7dB lower than in the case of continuous wave (CW), while it is about 1dB lower than that of 2087-6001-00 type in the CW case. At 4.1 GHz, given the pulse-width of 20 ns, the sensitivity of WB-CD01 type is about 0.2 dB higher than in the CW case, while it is almost the same as the CW case for the other given pulse-width. For all the given pulse-width at 4.1 GHz, the sensitivity of 2087-6001-00 type is almost the same as in CW case. In the cases of pulsed microwaves, an overs
