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RSS1998 Vol. 10, No. 04
Recommend Articles
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1998,
10.
Abstract:
In this paper, a laser beam shaping system has been established on the basis of a 37/55element deformable mirror and a S-H sensor. Using these devices and theories of wave-plane aberration and light diffraction, He-Ne laser beam with circular Gaussian profile can be transformed to uniform rectangular profile at the focal plane successfully. The limitatins of optical system to reshape uniform profiles are discussed by analyzing the experimental results．
In this paper, a laser beam shaping system has been established on the basis of a 37/55element deformable mirror and a S-H sensor. Using these devices and theories of wave-plane aberration and light diffraction, He-Ne laser beam with circular Gaussian profile can be transformed to uniform rectangular profile at the focal plane successfully. The limitatins of optical system to reshape uniform profiles are discussed by analyzing the experimental results．
1998,
10.
Abstract:
Usnig diffraction integral theory, the propagation properties of laser beams passing through a cylindrical hohlraum in indirect-driven laser fusion have been studied. The intensity distributions at the entrance hole and on the wall of the cylindrical hohlraum have been given. Our results have been compared with those calculated using geometric optics, thus the condition, under which geometric optics is valid, has been obtained．
Usnig diffraction integral theory, the propagation properties of laser beams passing through a cylindrical hohlraum in indirect-driven laser fusion have been studied. The intensity distributions at the entrance hole and on the wall of the cylindrical hohlraum have been given. Our results have been compared with those calculated using geometric optics, thus the condition, under which geometric optics is valid, has been obtained．
1998,
10.
Abstract:
Variable scale method,a sort of optimal method,is used in design of optical system,meanwhile,the technique of using the ‘escape function’ for variable scale method in design is describle. It is important how to chose the values for two parameters H- and W- in the escape function,that will decide whether escape the ‘trap’ in a local minimum. A typical optical system with this technique by means of the program developed with C language was designed successfully.
Variable scale method,a sort of optimal method,is used in design of optical system,meanwhile,the technique of using the ‘escape function’ for variable scale method in design is describle. It is important how to chose the values for two parameters H- and W- in the escape function,that will decide whether escape the ‘trap’ in a local minimum. A typical optical system with this technique by means of the program developed with C language was designed successfully.
1998,
10.
Abstract:
The motion regularity of the electron in frift electron beam were studied. The expressions of the motion trajectory and the drift velocity of electron were obtained in added externally electric field, toroidal magnetic field and selffield. For two schemes of setting cathode, forming conditions, shapes, steady conditions, and required voltages of drift electron beam were discussed and compared, and it was better to set the cathode vertically to toroidal magnetic field.
The motion regularity of the electron in frift electron beam were studied. The expressions of the motion trajectory and the drift velocity of electron were obtained in added externally electric field, toroidal magnetic field and selffield. For two schemes of setting cathode, forming conditions, shapes, steady conditions, and required voltages of drift electron beam were discussed and compared, and it was better to set the cathode vertically to toroidal magnetic field.
1998,
10.
Abstract:
One dimensional multi-group radiation transport program is used to simulate the process of X-rays heating Au disk. The reemission delay times of Au disk vs X rays photon energy were given and compared with recent experimental results. It is found that the theoretical results fitted well with the experimental results, especially the trend of reemission delay time. This proved that the one dimensional multigroup radiation transport program can do well in simulating the experimental process of X rays heating Au disk．
One dimensional multi-group radiation transport program is used to simulate the process of X-rays heating Au disk. The reemission delay times of Au disk vs X rays photon energy were given and compared with recent experimental results. It is found that the theoretical results fitted well with the experimental results, especially the trend of reemission delay time. This proved that the one dimensional multigroup radiation transport program can do well in simulating the experimental process of X rays heating Au disk．
1998,
10.
Abstract:
Linear RTI growth rates simulated by EUL2D at various cases with different perturbation wavelengths are given, and are compared with Takabe formula and Sanz formula. Numerical results of single mode nonlinear RTI evolution with and without electron conduction are compared. 2D simulated results of linear RTI growth rates are quite good agreement with the Sanz formula. The Takabe formula is not agreements with 2D simulations at larger ablative velocity or wider ablative surface.
Linear RTI growth rates simulated by EUL2D at various cases with different perturbation wavelengths are given, and are compared with Takabe formula and Sanz formula. Numerical results of single mode nonlinear RTI evolution with and without electron conduction are compared. 2D simulated results of linear RTI growth rates are quite good agreement with the Sanz formula. The Takabe formula is not agreements with 2D simulations at larger ablative velocity or wider ablative surface.
1998,
10.
Abstract:
In order to satisfy the requirement of the soft Xray energy measurement, a gated integrator which integrates the output current to Xray detectors in a limited time has been developed.The tests with signal sources show that the efficient gate width in which the current is integrated is about 7.8ns and the integral nonlinearity is less than 3%. The maximum error between the integral results of the gated integrator and of oscilloscope is less than 5% of the scale range of the gated integrator．
In order to satisfy the requirement of the soft Xray energy measurement, a gated integrator which integrates the output current to Xray detectors in a limited time has been developed.The tests with signal sources show that the efficient gate width in which the current is integrated is about 7.8ns and the integral nonlinearity is less than 3%. The maximum error between the integral results of the gated integrator and of oscilloscope is less than 5% of the scale range of the gated integrator．
1998,
10.
Abstract:
In the paper technology of filling diagnostic gas Ne with high temperature has been discussed. The factors effecting pressure in glass microsphere have been analyzed. The best condition of filling gas Ne in glass microsphere has been gained. The gas Ne has been filled in glass microsphere with pressure of 0.02～3MPa by this method．
In the paper technology of filling diagnostic gas Ne with high temperature has been discussed. The factors effecting pressure in glass microsphere have been analyzed. The best condition of filling gas Ne in glass microsphere has been gained. The gas Ne has been filled in glass microsphere with pressure of 0.02～3MPa by this method．
1998,
10.
Abstract:
Using London's model, physics of X-ray laser propagation and amplification in laser-plasma of the foil target is studied analytically. The analytical results agree well with London's numerical calculation. In accuracy of steepest-descents-approximation adopted in London's calculation was found．
Using London's model, physics of X-ray laser propagation and amplification in laser-plasma of the foil target is studied analytically. The analytical results agree well with London's numerical calculation. In accuracy of steepest-descents-approximation adopted in London's calculation was found．
1998,
10.
Abstract:
The performance of an inplane lens field emission cathode, based upon a unit cell with a conical field emitter tip, gate, in-plane lens, and anode, are evaluated via MAGIC particle-in-cell simulation code. Electron emission is calculated from the Fowler-Nordheim equation. The trajectories and phase space were evaluated, the normalized beam emittance εn= 1.09×10-9m·rad and brightness Bn= 3.79×10-9A/(m·rad)２ for a typical in-plane lens Field Emission Cathodes．
The performance of an inplane lens field emission cathode, based upon a unit cell with a conical field emitter tip, gate, in-plane lens, and anode, are evaluated via MAGIC particle-in-cell simulation code. Electron emission is calculated from the Fowler-Nordheim equation. The trajectories and phase space were evaluated, the normalized beam emittance εn= 1.09×10-9m·rad and brightness Bn= 3.79×10-9A/(m·rad)２ for a typical in-plane lens Field Emission Cathodes．
1998,
10.
Abstract:
Numerical simulations of the coaxial vircator are presented in this paper. The anode cavity provides a resonant mechanism for the interaction of beams and cavity modes. The peak output power occurred when the character impedance of transmission line matched the diode impedance, and the bandwidth of output microwave of coaxial vircator is much narrow than planar vircator. The scaling relation between impedance of coaxial diode and geometry dimensions was approximately determined by simulation results. Comparing with the positively pulsed coaxial vircator, a negatively pulsed one was higher efficiency and more narrow output microwave bandwidth．
Numerical simulations of the coaxial vircator are presented in this paper. The anode cavity provides a resonant mechanism for the interaction of beams and cavity modes. The peak output power occurred when the character impedance of transmission line matched the diode impedance, and the bandwidth of output microwave of coaxial vircator is much narrow than planar vircator. The scaling relation between impedance of coaxial diode and geometry dimensions was approximately determined by simulation results. Comparing with the positively pulsed coaxial vircator, a negatively pulsed one was higher efficiency and more narrow output microwave bandwidth．
1998,
10.
Abstract:
A two and one half dimensional electromagnetic relativistic particle-in-cell simulation code has been used to investigate the nonlinear beamwave interaction and other optimization issues of a 3cm relativistic backward wave oscillator in the paper. The simulation results such as microwave generating efficiency, peak power and frequency are reasonable agreement with experiment data. The dependence of the power on electron beam voltage, eletron beam current, slow wave structure geometry and magnetic guide field were simulated, optimum conditions for the device have been obtained.
A two and one half dimensional electromagnetic relativistic particle-in-cell simulation code has been used to investigate the nonlinear beamwave interaction and other optimization issues of a 3cm relativistic backward wave oscillator in the paper. The simulation results such as microwave generating efficiency, peak power and frequency are reasonable agreement with experiment data. The dependence of the power on electron beam voltage, eletron beam current, slow wave structure geometry and magnetic guide field were simulated, optimum conditions for the device have been obtained.
1998,
10.
Abstract:
ＴWe have used a two-dimension fully electromagnetic particle in cell(PIC) simulation to study the relativistic A-６ magnetron designed by Palevsky and Bakefi, and analysed the physics picture. Specially, we have researched the relation of the output impedance with the output power and operating modes and given the optimal output impedance corresponding the maximum output power．
ＴWe have used a two-dimension fully electromagnetic particle in cell(PIC) simulation to study the relativistic A-６ magnetron designed by Palevsky and Bakefi, and analysed the physics picture. Specially, we have researched the relation of the output impedance with the output power and operating modes and given the optimal output impedance corresponding the maximum output power．
1998,
10.
Abstract:
The method of measurement of the HPM power and modes in circular waveguide are introduced in this paper. The calibration system of the effective area and the timeresponse of the probes is also described. Both theoretic analysis and experiment indicates that the measurement method of probes has a comparatively perfect accuracy on measuring HPM source which has eignmode．
The method of measurement of the HPM power and modes in circular waveguide are introduced in this paper. The calibration system of the effective area and the timeresponse of the probes is also described. Both theoretic analysis and experiment indicates that the measurement method of probes has a comparatively perfect accuracy on measuring HPM source which has eignmode．
1998,
10.
Abstract:
Undulator rms phase error is expressed as function of the magnet peak field distribution. It can be used as the objective function for practical undulator performance optimization. An simple analytical computation formula is given for field signature of the shims to predict the field and phase perturbation according the shim position, size, thickness and magnet gap．
Undulator rms phase error is expressed as function of the magnet peak field distribution. It can be used as the objective function for practical undulator performance optimization. An simple analytical computation formula is given for field signature of the shims to predict the field and phase perturbation according the shim position, size, thickness and magnet gap．
1998,
10.
Abstract:
In this paper, the investigation of an extracavity frequencydoubling of a supersonic CW chemical oxygeniodine laser using LBO crystal is firstly described. The 2nd harmonic conversion by type Ⅱ phase matching has been obtained with maximum conversion efficiency as 0.17% ．
In this paper, the investigation of an extracavity frequencydoubling of a supersonic CW chemical oxygeniodine laser using LBO crystal is firstly described. The 2nd harmonic conversion by type Ⅱ phase matching has been obtained with maximum conversion efficiency as 0.17% ．
1998,
10.
Abstract:
In this paper, the configurations for wavefront sensor subapertures and deformable mirror actuator in cleaning laser beam adaptive optics sysem have been simulated, and controlling gradients directly、Fried mode and Southwell mode of zonal wavefront control have been compared. Finally the result of the wavefront correcting ability and stability of controlling gradients directly is the best in these three wavefront control algorithms is presented.
In this paper, the configurations for wavefront sensor subapertures and deformable mirror actuator in cleaning laser beam adaptive optics sysem have been simulated, and controlling gradients directly、Fried mode and Southwell mode of zonal wavefront control have been compared. Finally the result of the wavefront correcting ability and stability of controlling gradients directly is the best in these three wavefront control algorithms is presented.
1998,
10.
Abstract:
The 61 element discrete piezoelectric deformable mirror(DM61) is used to correct wavefront errors.A lot of difficulties are appeared in our development works because the demads of DM61 now are more than that of the mirror,developed before such as element number(61) and deformation (±３μm）.Methods are adopted from theory analysis and technics investigation to make the DM61 be used in the connection of AOS and ATP to enhance the trace accuracy successfully.
The 61 element discrete piezoelectric deformable mirror(DM61) is used to correct wavefront errors.A lot of difficulties are appeared in our development works because the demads of DM61 now are more than that of the mirror,developed before such as element number(61) and deformation (±３μm）.Methods are adopted from theory analysis and technics investigation to make the DM61 be used in the connection of AOS and ATP to enhance the trace accuracy successfully.
1998,
10.
Abstract:
A coherent harmonic generation FEL experiment is under way in 800MeV electron storage ring in National Synchrotron Radiation Laboratory, USTC. Spon taneous emission spectrum of a optical klystron for the experiment has been measured, a modulation factor of 0.7 has been obtained. This paper presents measurements of spontaneous emission spectrum and enhancement of modulation factor．
A coherent harmonic generation FEL experiment is under way in 800MeV electron storage ring in National Synchrotron Radiation Laboratory, USTC. Spon taneous emission spectrum of a optical klystron for the experiment has been measured, a modulation factor of 0.7 has been obtained. This paper presents measurements of spontaneous emission spectrum and enhancement of modulation factor．
1998,
10.
Abstract:
The general solution of scalar magnetic potential at any interior point of a cylindrical helix wiggler was attained and the expression of magnetic field on axis was also given by solving Lapace's equation. The magnetic field distributions of several kinds of helical wiggler were derived from combination and superposition of the magnetic field, such as right-handed bifilar helix wiggler, lefthanded fifilar helix wiggler,crossed double helix wiggler, autoguide field wiggler, multiwound wiggler and asymmetric wound wiggler and so on．
The general solution of scalar magnetic potential at any interior point of a cylindrical helix wiggler was attained and the expression of magnetic field on axis was also given by solving Lapace's equation. The magnetic field distributions of several kinds of helical wiggler were derived from combination and superposition of the magnetic field, such as right-handed bifilar helix wiggler, lefthanded fifilar helix wiggler,crossed double helix wiggler, autoguide field wiggler, multiwound wiggler and asymmetric wound wiggler and so on．
1998,
10.
Abstract:
The governing equations of non-linear dynamic response of an axisymmetric elastic thin circular plate subjected to an arbitrarily transverse force and a thermal energy deposit are formulated.Deformation features of thin circular plates and the factors that affect failure are discussed by a quasi-static analysis.It is shown that thermal buckling is one of the major failure modes of thin circular plates in the case of short duration thermal energy deposit. Thermal buckling always occurs before reverse bulging or reverse plugging.Similar to the increase of the transverse load,the increase of the power level of thermal energy deposit will accelerate the thermal buckling.The temperature dependence of material properties and the time-space distribution of thermal energy deposit both significantl
The governing equations of non-linear dynamic response of an axisymmetric elastic thin circular plate subjected to an arbitrarily transverse force and a thermal energy deposit are formulated.Deformation features of thin circular plates and the factors that affect failure are discussed by a quasi-static analysis.It is shown that thermal buckling is one of the major failure modes of thin circular plates in the case of short duration thermal energy deposit. Thermal buckling always occurs before reverse bulging or reverse plugging.Similar to the increase of the transverse load,the increase of the power level of thermal energy deposit will accelerate the thermal buckling.The temperature dependence of material properties and the time-space distribution of thermal energy deposit both significantl
1998,
10.
Abstract:
This paper reviews that the various reported laserinduced effects, especially the softdamage or harddamage ones, of the CCD detectors or the familiar materials structures, collects various kinds of laserinduced damage thresholds, and gives those experimental methods. By comparing each other, the laserinduced damage mechanisms and theoretical models have been analyzed．
This paper reviews that the various reported laserinduced effects, especially the softdamage or harddamage ones, of the CCD detectors or the familiar materials structures, collects various kinds of laserinduced damage thresholds, and gives those experimental methods. By comparing each other, the laserinduced damage mechanisms and theoretical models have been analyzed．
1998,
10.
Abstract:
The ignition of metal enveloped explosive by repetitively rulsed YAG laser and corresponding damaging mechanism and mode of metal/explosive structure are investigated from experiments. The relationship between laser output duration needed by ignition of metal enveloped RDX、PETN explosive and laser intensity is given. Preliminary computational simulation show that the laser output time needed by explosive ignition is obviously dependent on laser intensity and spot size ．
The ignition of metal enveloped explosive by repetitively rulsed YAG laser and corresponding damaging mechanism and mode of metal/explosive structure are investigated from experiments. The relationship between laser output duration needed by ignition of metal enveloped RDX、PETN explosive and laser intensity is given. Preliminary computational simulation show that the laser output time needed by explosive ignition is obviously dependent on laser intensity and spot size ．
1998,
10.
Abstract:
Under the irradiation of the CW-YAG laser, the damage thresholds of one-nuit and multi-unit PC-type HgCdTe detector are given in this paper. It also gives the damage thresholds of different position of irradiation. The relation of the influence of operating current to damage thresholds has been investigated experimentally. The results of measurement have been analyzed．
Under the irradiation of the CW-YAG laser, the damage thresholds of one-nuit and multi-unit PC-type HgCdTe detector are given in this paper. It also gives the damage thresholds of different position of irradiation. The relation of the influence of operating current to damage thresholds has been investigated experimentally. The results of measurement have been analyzed．
1998,
10.
Abstract:
This article deals with the physical process when a high intensity broadband KrF Laser beam passes through gaseous Raman medium. We discuss the parameter dependence of the threshold power and conversion effeciency of SRS.Based on the analysis of SRS initiation and calculation of stoke laser modes formation,as well as the spatial propagation and amplification, we focus on influence of focus position on physical process, especially the Stokes output characteristic.By comparison between experimental results and theoretical expectation,we clarify some ambiguous viewpoints widely existing in the literature of SRS.
This article deals with the physical process when a high intensity broadband KrF Laser beam passes through gaseous Raman medium. We discuss the parameter dependence of the threshold power and conversion effeciency of SRS.Based on the analysis of SRS initiation and calculation of stoke laser modes formation,as well as the spatial propagation and amplification, we focus on influence of focus position on physical process, especially the Stokes output characteristic.By comparison between experimental results and theoretical expectation,we clarify some ambiguous viewpoints widely existing in the literature of SRS.
1998,
10.
Abstract:
The thermal capability of material, the surface defect and the fabrication techniques of the mirrors using in high power contiune laser are analyzed in this paper. Several features for manufacturing mirror must be considered, which are the ratio S of the thermal capability, microstructure, size of the surface defect, the crystal direction on the mirror material and design of technic for the mirror. Moreover the results of experimentation are given．
The thermal capability of material, the surface defect and the fabrication techniques of the mirrors using in high power contiune laser are analyzed in this paper. Several features for manufacturing mirror must be considered, which are the ratio S of the thermal capability, microstructure, size of the surface defect, the crystal direction on the mirror material and design of technic for the mirror. Moreover the results of experimentation are given．
1998,
10.
Abstract:
In this paper,a numeerical computational method is presented to solve 3×3 sodium iodide detector energy deposit spectrum and response functions for gamma-rays with energy upto 25MeV in the field of Neutron Logging. The results are satisfied.
In this paper,a numeerical computational method is presented to solve 3×3 sodium iodide detector energy deposit spectrum and response functions for gamma-rays with energy upto 25MeV in the field of Neutron Logging. The results are satisfied.
1998,
10.
Abstract:
Comparison of autoionization and dielectronic capture with dielectronic recombination in ion population in Ge plasma was given. Solving the coupled rate equations, the contribution factors from Flike and Nelike ions on the lower and the upper laser level of 19.6 and 23.6 nm lines, and the ionization rates of Nalike and Nelike ions were studied． Further more, inversion factor and gain at 19.6 and 23.6nm lines were discussed ．
Comparison of autoionization and dielectronic capture with dielectronic recombination in ion population in Ge plasma was given. Solving the coupled rate equations, the contribution factors from Flike and Nelike ions on the lower and the upper laser level of 19.6 and 23.6 nm lines, and the ionization rates of Nalike and Nelike ions were studied． Further more, inversion factor and gain at 19.6 and 23.6nm lines were discussed ．
1998,
10.
Abstract:
A great number of numerical calculations have been performed to compare the characteristics of pumping cavities in the singlesegment and multisegment amplifiers. The results would be useful for the optimal prototype design.
A great number of numerical calculations have been performed to compare the characteristics of pumping cavities in the singlesegment and multisegment amplifiers. The results would be useful for the optimal prototype design.
1998,
10.
Abstract:
Beam longitudinal instabilities excited by the beam cavity interaction are one of the most important instabilities in the high energy electron accelerators.Based on the energy electron accelerators.Based on the longitudinal motion equation of the particle,the longitudinal instability of m=1 mode excited by the beam cavity interaction in the cases of single bunch and multi-bunch operations was discussed in detail.The results for the Hefei Light Source were given.
Beam longitudinal instabilities excited by the beam cavity interaction are one of the most important instabilities in the high energy electron accelerators.Based on the energy electron accelerators.Based on the longitudinal motion equation of the particle,the longitudinal instability of m=1 mode excited by the beam cavity interaction in the cases of single bunch and multi-bunch operations was discussed in detail.The results for the Hefei Light Source were given.
1998,
10.
Abstract:
The electron beams generated from the irradiation LINAC which is used for industry irradiation must be scanned. The current in the scanning coil should be quasitriangle wave to make the beams uniformity in the scanning direction. In the system the period of the scanning current is completely synchronized by the major pulse of the modulator in order to avoid the beat. The highest speed of the irradiation bed can be determined by the frequency of modulator, scanning width, and the size of electron beam spot to ensure the high efficient irradiation．
The electron beams generated from the irradiation LINAC which is used for industry irradiation must be scanned. The current in the scanning coil should be quasitriangle wave to make the beams uniformity in the scanning direction. In the system the period of the scanning current is completely synchronized by the major pulse of the modulator in order to avoid the beat. The highest speed of the irradiation bed can be determined by the frequency of modulator, scanning width, and the size of electron beam spot to ensure the high efficient irradiation．
1998,
10.
Abstract:
The experiment result of a high voltage pseudospark discharge driven by a pulse line accelerator is presented. The pulse line accelerator consists of a 10stage Marx generator and a modified pulse forming line. A high brightness electron beam of a current about 10kA is obtained under a discharge voltage of 300kA in a low pressure nitrogen gas .
The experiment result of a high voltage pseudospark discharge driven by a pulse line accelerator is presented. The pulse line accelerator consists of a 10stage Marx generator and a modified pulse forming line. A high brightness electron beam of a current about 10kA is obtained under a discharge voltage of 300kA in a low pressure nitrogen gas .
1998,
10.
Abstract:
In this paper,the relation between the beam emittance and the condition of dispersion free at long straight sections for HLS storage ring was presented; The calculation of the lowest emittance of the storage ring was carried out while considering H function matching condition; Theory basis was afforded for the multi-modes operation of the light source.
In this paper,the relation between the beam emittance and the condition of dispersion free at long straight sections for HLS storage ring was presented; The calculation of the lowest emittance of the storage ring was carried out while considering H function matching condition; Theory basis was afforded for the multi-modes operation of the light source.
