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RSS1999 Vol. 11, No. 01
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1999,
11.
Abstract:
The dielectronic recombination in average atom model has been studied by coupling the hydrodynamic equations with nonlocal thermalequilibrium electron population equtions,the effect of dielectronic recombination on the high power laser produced Au plasma has been investigated. It has been shown that in comparison with radiative and threebody recombination process the dielectronic recombination is the dominant one in a part of coroa region of high temperature and low density Au plasma produced by high power laser．
The dielectronic recombination in average atom model has been studied by coupling the hydrodynamic equations with nonlocal thermalequilibrium electron population equtions,the effect of dielectronic recombination on the high power laser produced Au plasma has been investigated. It has been shown that in comparison with radiative and threebody recombination process the dielectronic recombination is the dominant one in a part of coroa region of high temperature and low density Au plasma produced by high power laser．
1999,
11.
Abstract:
The possibility of measuring radiative temperature inside the hohlraum by shock wave method and the possible measuring precision have been studied using analysis and numerical simulation . The results show it is reliable method that the radiative temperature inside the hohlraum is deduced by accurately measuring the variations of speed and pressure of shock wave in the Al cuniform target, and whick can also greatly improve measuring precision．
The possibility of measuring radiative temperature inside the hohlraum by shock wave method and the possible measuring precision have been studied using analysis and numerical simulation . The results show it is reliable method that the radiative temperature inside the hohlraum is deduced by accurately measuring the variations of speed and pressure of shock wave in the Al cuniform target, and whick can also greatly improve measuring precision．
1999,
11.
Abstract:
The CV(at 227.1nm) line has been measured with Optical Spect roscope Multichannel Analysis. The local ion temperature and rotation velocity has been derived using a chosenpoint fitting technique．
The CV(at 227.1nm) line has been measured with Optical Spect roscope Multichannel Analysis. The local ion temperature and rotation velocity has been derived using a chosenpoint fitting technique．
1999,
11.
Abstract:
The spectrum of a laserproduced plasｍas of gold in the range 0.346 ～0.372nm is considered as the production of the spinorbitsplit arrays of the 3d5f、3p5s transitions for Au 49+Au 52+. The main characteristic parameters, mean wavelength, the full width at half maximum and total transition intensity,of subarrays whose mean wavelength belongs to the above range is computed in detail by means of spinorbitsplit array model,the excellent agreement between theoretical calculation and experiment indicates the possibility o f use for precise diagnostics of plasmas.
The spectrum of a laserproduced plasｍas of gold in the range 0.346 ～0.372nm is considered as the production of the spinorbitsplit arrays of the 3d5f、3p5s transitions for Au 49+Au 52+. The main characteristic parameters, mean wavelength, the full width at half maximum and total transition intensity,of subarrays whose mean wavelength belongs to the above range is computed in detail by means of spinorbitsplit array model,the excellent agreement between theoretical calculation and experiment indicates the possibility o f use for precise diagnostics of plasmas.
1999,
11.
Abstract:
In this paper, the precise focusing and diagnosis experimental system for laser beams in ICF target chamber is introduced. The system is controlled by computer. In process of focusing a series data of displacement in axial direction and relative area of focus spots are acquired. According to the functional curvature the accurate position of focal plane is determined. The construction of the system is simple,the system is controlled conveniently and runs quickly．
In this paper, the precise focusing and diagnosis experimental system for laser beams in ICF target chamber is introduced. The system is controlled by computer. In process of focusing a series data of displacement in axial direction and relative area of focus spots are acquired. According to the functional curvature the accurate position of focal plane is determined. The construction of the system is simple,the system is controlled conveniently and runs quickly．
1999,
11.
Abstract:
Timeintegrated spectrum of 3ω0/2 light in plasma produced by 1.053μm laser irradiating on Audisk is shown in this paper． Based on the measurement of redshifted p eak and blueshifted peak. The temperature of electron in interacti on region and the plasma expansion speed in onequarter critical electron density layer are obtained. The experiment results agree well with nonlinear saturation theory of Two PlasmonDecay.
Timeintegrated spectrum of 3ω0/2 light in plasma produced by 1.053μm laser irradiating on Audisk is shown in this paper． Based on the measurement of redshifted p eak and blueshifted peak. The temperature of electron in interacti on region and the plasma expansion speed in onequarter critical electron density layer are obtained. The experiment results agree well with nonlinear saturation theory of Two PlasmonDecay.
1999,
11.
Abstract:
The absorption efficiency of the pumping energy and laser ablation and the pumping laser propagate amony a carbon fibertarget are calculated using 1D noLTE radiation hydromechanics code and geometrical optics path code, in which the refraction effect is considered. The results show that there is a distribution along the line focusing width from the centre to the edging. It has less effect to the laser refract, near the centre of the line focusing width, and it has obvious effect to the laser refract, in the edging of the line focusing width.As a result of calculation the ablative mass of the plasma turns smaller ,and the absorption efficiency of laser total energy is reduced about 10%．
The absorption efficiency of the pumping energy and laser ablation and the pumping laser propagate amony a carbon fibertarget are calculated using 1D noLTE radiation hydromechanics code and geometrical optics path code, in which the refraction effect is considered. The results show that there is a distribution along the line focusing width from the centre to the edging. It has less effect to the laser refract, near the centre of the line focusing width, and it has obvious effect to the laser refract, in the edging of the line focusing width.As a result of calculation the ablative mass of the plasma turns smaller ,and the absorption efficiency of laser total energy is reduced about 10%．
1999,
11.
Abstract:
Using the detailed configuration accounting with the term structures treated by the unresolved transition array model, we present a method to calculate the transmission spectra for highpower laserproduced plasmas in local thermodynamic equilibrium. Based on the quantum defect theory, the UTA parameters with high principal quantum numbers can be conveniently calculated with much less computational efforts. This ensure us to handle a huge number of transition arrays from many configurations occurrin g in typical laserproduced middle Z and high Z plasmas．
Using the detailed configuration accounting with the term structures treated by the unresolved transition array model, we present a method to calculate the transmission spectra for highpower laserproduced plasmas in local thermodynamic equilibrium. Based on the quantum defect theory, the UTA parameters with high principal quantum numbers can be conveniently calculated with much less computational efforts. This ensure us to handle a huge number of transition arrays from many configurations occurrin g in typical laserproduced middle Z and high Z plasmas．
1999,
11.
Abstract:
The main purpose of this paper is to make some investigation to the radiation propagation on basis of aerodynamics and to provide some interesting results. If a radiation wave front,what we shall simply is called the discrete surface,the configuration of fluid field and developing laws of radiation propagation and ablation and others has been researched on basis of gas dynamics frame.The visualized physics picture is reproduced．
The main purpose of this paper is to make some investigation to the radiation propagation on basis of aerodynamics and to provide some interesting results. If a radiation wave front,what we shall simply is called the discrete surface,the configuration of fluid field and developing laws of radiation propagation and ablation and others has been researched on basis of gas dynamics frame.The visualized physics picture is reproduced．
1999,
11.
Abstract:
The mechanisms of CLBO crystal using for high efficiency third harmonic conversion are discussed, and the basic characters of high efficiency harmonic conversion on theory is analyzed. The numerical simulation of basic parameter s of third harmonic conversion for CLBO crystal on the high power laser facility are presented. Compared the characters of third harmonic conversion with KDP cr ystal. Provided basic conditions using for to generate high efficiency third har monic conversion of CLBO crystal.
The mechanisms of CLBO crystal using for high efficiency third harmonic conversion are discussed, and the basic characters of high efficiency harmonic conversion on theory is analyzed. The numerical simulation of basic parameter s of third harmonic conversion for CLBO crystal on the high power laser facility are presented. Compared the characters of third harmonic conversion with KDP cr ystal. Provided basic conditions using for to generate high efficiency third har monic conversion of CLBO crystal.
RESEACH ON THE MECHANISM OF EXCIMER LASER SURFACE PROCESSING FOR IMPROVED ADHESI VE FORCE OF POLYMER
1999,
11.
Abstract:
The interaction b etween the laser and liquid thin film on polymer substrate system was theoretical analyzed using heat equations. The results show that the increasement of ad hesive force of polymer surface is related to the vapourizing of surface liquid film and melting of the substrate surface. The bond of polymer molecule is broken by laser irradiation, some of fluorine atoms is replaced by hydrogen atomsd uring the process.
The interaction b etween the laser and liquid thin film on polymer substrate system was theoretical analyzed using heat equations. The results show that the increasement of ad hesive force of polymer surface is related to the vapourizing of surface liquid film and melting of the substrate surface. The bond of polymer molecule is broken by laser irradiation, some of fluorine atoms is replaced by hydrogen atomsd uring the process.
1999,
11.
Abstract:
The optimal design for hig hpower multipass laser amplifier systems has been performed using beam prop agation code. The methods and results obtained in this paper are applicable to the design of highpower laser amplifier system．
The optimal design for hig hpower multipass laser amplifier systems has been performed using beam prop agation code. The methods and results obtained in this paper are applicable to the design of highpower laser amplifier system．
1999,
11.
Abstract:
The time varying thermal deformation model of the window irradiated high power laser is analyzed in detai l. By finitetemperature field distributions and thermal de formati on of elememt method, the SiOcooling window are studied. Under the same condition of 2 windows and the center absorbed 50W laser power, the maximum deformation of the normal SiO 2 window is 2.4μm, and that of the central cooled window is 1.2μm. The calc ulation results argee with the experimental value perfectly．
The time varying thermal deformation model of the window irradiated high power laser is analyzed in detai l. By finitetemperature field distributions and thermal de formati on of elememt method, the SiOcooling window are studied. Under the same condition of 2 windows and the center absorbed 50W laser power, the maximum deformation of the normal SiO 2 window is 2.4μm, and that of the central cooled window is 1.2μm. The calc ulation results argee with the experimental value perfectly．
1999,
11.
Abstract:
The mechanical oscillation of the fast steering mirror in adaptive optics system and its effect on control stability are discussed in this paper. The dynamic model of FSM is established on base of measured data. The lowpass filter (LPF) and the double secon drank filter (DSF) are tested to reduce the mechanical oscillation of FSM. It is showed that both the control stability and control bandwidth are improved by the filter technology.
The mechanical oscillation of the fast steering mirror in adaptive optics system and its effect on control stability are discussed in this paper. The dynamic model of FSM is established on base of measured data. The lowpass filter (LPF) and the double secon drank filter (DSF) are tested to reduce the mechanical oscillation of FSM. It is showed that both the control stability and control bandwidth are improved by the filter technology.
1999,
11.
Abstract:
This paper introduces a new type of reflector mount array, which is designed for main amplifier of ICF laser driver in China. The whole system utilizes a special array structure, in compliance with the requirement of a small distance among each beam of the laser system. The onebody joint drive structure and a flexible structure ensure the system with high adjusting accuracy and stability．
This paper introduces a new type of reflector mount array, which is designed for main amplifier of ICF laser driver in China. The whole system utilizes a special array structure, in compliance with the requirement of a small distance among each beam of the laser system. The onebody joint drive structure and a flexible structure ensure the system with high adjusting accuracy and stability．
1999,
11.
Abstract:
A study of a Gaussian fitting method for estimating subaperture centroids of ShackHartmann wavefront sensor has been made. The method is based on the prior knowledge that the intensity distribution of subapertures spot can be considered approximately Gaussian in form. We present results for several different light intensities and distances of subapertures spot both with and without detectors noise. A more accurate estimation of the local slopes can be achieved at low light levels in this way than with the standard firstmoment estimator.
A study of a Gaussian fitting method for estimating subaperture centroids of ShackHartmann wavefront sensor has been made. The method is based on the prior knowledge that the intensity distribution of subapertures spot can be considered approximately Gaussian in form. We present results for several different light intensities and distances of subapertures spot both with and without detectors noise. A more accurate estimation of the local slopes can be achieved at low light levels in this way than with the standard firstmoment estimator.
1999,
11.
Abstract:
The propagation properties of a prebunched electron be am in free electron lasers is investigated in this paper.Results show that: As the beam pr opagates downstream, the amplitude of the fundamental modulation current is enha nced and its phase keeps unchanged,while both the amplitude and phase of the hig h harmonic modulation current remain unchanged．
The propagation properties of a prebunched electron be am in free electron lasers is investigated in this paper.Results show that: As the beam pr opagates downstream, the amplitude of the fundamental modulation current is enha nced and its phase keeps unchanged,while both the amplitude and phase of the hig h harmonic modulation current remain unchanged．
1999,
11.
Abstract:
According to the basic element of MOS device, the analytic expressions of function relation between output and input of CCD are derived, and its various photoelectric characteristics (sensitivity, crosstalk threshold power, etc.)are obtained, the temperature effect is studied qualitatively and the countermeasure against laser jamming is discussed ．
According to the basic element of MOS device, the analytic expressions of function relation between output and input of CCD are derived, and its various photoelectric characteristics (sensitivity, crosstalk threshold power, etc.)are obtained, the temperature effect is studied qualitatively and the countermeasure against laser jamming is discussed ．
1999,
11.
Abstract:
The study of spontaneous emission of an optical klystron has been made. The modulation rate of the spontaneous emission spectrum has reached 0.80. The coherent harmonic generation experiment will be carried out soon. This paperd escribes the considerations of the experiment, the measurement method of the rat io between coherent emission and incoherent emission on third harmonic, the experiment setup and laser beam alignment and synchronization with electron beam.
The study of spontaneous emission of an optical klystron has been made. The modulation rate of the spontaneous emission spectrum has reached 0.80. The coherent harmonic generation experiment will be carried out soon. This paperd escribes the considerations of the experiment, the measurement method of the rat io between coherent emission and incoherent emission on third harmonic, the experiment setup and laser beam alignment and synchronization with electron beam.
1999,
11.
Abstract:
A random method used for improving light throughput of a soft Xray multilayer mirror has been developed. It is demon strated that layer thickness disorder yields band broadening and increased integrated reflectivity,and achieved 75% increase in integrated reflctivity in the 12.4～20.1nm spectral range with respect to periodic multilayer with its first Bragg peak in the center of that range．
A random method used for improving light throughput of a soft Xray multilayer mirror has been developed. It is demon strated that layer thickness disorder yields band broadening and increased integrated reflectivity,and achieved 75% increase in integrated reflctivity in the 12.4～20.1nm spectral range with respect to periodic multilayer with its first Bragg peak in the center of that range．
1999,
11.
Abstract:
China Superconducting wiggler, or WLS (wavelength shifter), generates short wavelength SR. WLS effects and modeling are studied. This paper focuses on 2 creative pieces of the work: estimation of the WLS effects, giving the biggest 1st and 3rd order Taylorintegrals; precise modeling of the linear effect with 3 edge-angled sterms in field piecewisely constant magnets．
China Superconducting wiggler, or WLS (wavelength shifter), generates short wavelength SR. WLS effects and modeling are studied. This paper focuses on 2 creative pieces of the work: estimation of the WLS effects, giving the biggest 1st and 3rd order Taylorintegrals; precise modeling of the linear effect with 3 edge-angled sterms in field piecewisely constant magnets．
1999,
11.
Abstract:
In the paper, all of measurement results of transverse magnet field of optical klystron are given, including the distribution on axis, magnet field uniformity and integrated field distribution. Furthermore, the random errors and harmonic magnet field are analyzed, and the integrated multipoles field is calculated. At last, the influence of nonzero integrated field on the close orbit of electron and the operation parameter of storage ring are discussed.
In the paper, all of measurement results of transverse magnet field of optical klystron are given, including the distribution on axis, magnet field uniformity and integrated field distribution. Furthermore, the random errors and harmonic magnet field are analyzed, and the integrated multipoles field is calculated. At last, the influence of nonzero integrated field on the close orbit of electron and the operation parameter of storage ring are discussed.
1999,
11.
Abstract:
The analysis of electron beam with weak pulsation in drifting tube filled with plasma was given in this paper, the beam with strong pulsation under the same condition was also studied accurately.The results show that whether in α area or in β area both the range and wave length of beam pulsation related to initial condition and plasma parameters although their pulsation properties werw different, there existed a optimum plasma density when the other condition was set.
The analysis of electron beam with weak pulsation in drifting tube filled with plasma was given in this paper, the beam with strong pulsation under the same condition was also studied accurately.The results show that whether in α area or in β area both the range and wave length of beam pulsation related to initial condition and plasma parameters although their pulsation properties werw different, there existed a optimum plasma density when the other condition was set.
1999,
11.
Abstract:
In this paper the phenomena of the virtual cathode oscillation in coaxial reflex triode are investigated by means of two and onehalf dimensional and fully electromagnetic MAGIC code. The PIC simulation indicates that the radiated mechanism is caused by the electrons oscillating between the real and virtual cathodes. In our simulation the instantaneous peak value of the output microwave power is an order of GW, the instantaneous peak value of efficiency is about 1 %. The efficiency can be improved by adding a collector in the center of cavity ．
In this paper the phenomena of the virtual cathode oscillation in coaxial reflex triode are investigated by means of two and onehalf dimensional and fully electromagnetic MAGIC code. The PIC simulation indicates that the radiated mechanism is caused by the electrons oscillating between the real and virtual cathodes. In our simulation the instantaneous peak value of the output microwave power is an order of GW, the instantaneous peak value of efficiency is about 1 %. The efficiency can be improved by adding a collector in the center of cavity ．
1999,
11.
Abstract:
A key technology of γEMP as sorted simulator is the synchronous operating between the γsimulator and the EMPsimulator.This paper analyzes the requirement of the assorted simulator to the synchronous capability of γsimulator and points out that the time jitter ΔTγ in γsimulator should reach to the level less than half width at half maximum of γpulse. Then, the difficulties and the methods of improving synchronous capability of FlashⅠ γsimulator are analyzed and reseached. The synchronous capability and feasibility of Flash1A as the γsimulator in the γEMP simulator system are discussed aslo.
A key technology of γEMP as sorted simulator is the synchronous operating between the γsimulator and the EMPsimulator.This paper analyzes the requirement of the assorted simulator to the synchronous capability of γsimulator and points out that the time jitter ΔTγ in γsimulator should reach to the level less than half width at half maximum of γpulse. Then, the difficulties and the methods of improving synchronous capability of FlashⅠ γsimulator are analyzed and reseached. The synchronous capability and feasibility of Flash1A as the γsimulator in the γEMP simulator system are discussed aslo.
1999,
11.
Abstract:
In this paper the techniques used in simulating SGEMP response were discussed, and some theoretical data and testing results got in resent years were presented. A general survey of the techniques that can be achieved in laboratory was given, focusing of those particularly applicable for SGEMP simulation. The techniques include direct X rays simulation, electron simulation, and direct voltage and current injection．
In this paper the techniques used in simulating SGEMP response were discussed, and some theoretical data and testing results got in resent years were presented. A general survey of the techniques that can be achieved in laboratory was given, focusing of those particularly applicable for SGEMP simulation. The techniques include direct X rays simulation, electron simulation, and direct voltage and current injection．
1999,
11.
Abstract:
In this paper,electromagnetic pulse (EMP) interaction with the boost flyer is simulated by the use of Finite Difference Time Domain method .Computational results indicate that a strong skin current is induced on the surface of the flyer under the action of EMP. The waveform of the induced current is a decreased ringing wave and the ringing period equals twice to the time of induced current flowing along the flyer. The results also indicate that the character of the current distributed over the flyer is stronger in the middle and weaker in both ends．
In this paper,electromagnetic pulse (EMP) interaction with the boost flyer is simulated by the use of Finite Difference Time Domain method .Computational results indicate that a strong skin current is induced on the surface of the flyer under the action of EMP. The waveform of the induced current is a decreased ringing wave and the ringing period equals twice to the time of induced current flowing along the flyer. The results also indicate that the character of the current distributed over the flyer is stronger in the middle and weaker in both ends．
