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RSS1993 Vol. 05, No. 04
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1993,
05: 485-488.
Abstract:
The method and apparatus for measurement of small signal of chemical oxygen-iodine laser (COIL) using pulsed photolytic iodine laser as a probe are described. The results of gain measurement are obtained. A brief discussion on the experimental results and the relevant errors are given.
The method and apparatus for measurement of small signal of chemical oxygen-iodine laser (COIL) using pulsed photolytic iodine laser as a probe are described. The results of gain measurement are obtained. A brief discussion on the experimental results and the relevant errors are given.
1993,
05: 489-492.
Abstract:
If“snow Crystals”, formed in the course of depriving the vapor in the singlet oxygen flow are taken into cavity with flow, the scattering loss of CW chemical oxyen -iodine laser at 1.315μm will be increased. So in this paper, by the means of double optical path, using a He -Ne laser as a probe laser, the scattering loss whether the " snow crystals" are appeared adn flow into the cavity is measured. The scattering loss is measured smaller than 1%, it shows that the singlet oxygen is in high quality before it flow into the cabity. This result also provides the data of scattering loss in cavity for resonator design.
If“snow Crystals”, formed in the course of depriving the vapor in the singlet oxygen flow are taken into cavity with flow, the scattering loss of CW chemical oxyen -iodine laser at 1.315μm will be increased. So in this paper, by the means of double optical path, using a He -Ne laser as a probe laser, the scattering loss whether the " snow crystals" are appeared adn flow into the cavity is measured. The scattering loss is measured smaller than 1%, it shows that the singlet oxygen is in high quality before it flow into the cabity. This result also provides the data of scattering loss in cavity for resonator design.
1993,
05: 493-497.
Abstract:
Considering the key chemical processes in COIL, and well-mixed working substance, a simplified one dimensional model for COIL is made out. The variations of gain coefficient, output power, power-to-volume ratio, chemical efficiency and lenth of lasing zone vs cavity temperature, pressure, proportion of components are calculated. An optimized working condition is given.
Considering the key chemical processes in COIL, and well-mixed working substance, a simplified one dimensional model for COIL is made out. The variations of gain coefficient, output power, power-to-volume ratio, chemical efficiency and lenth of lasing zone vs cavity temperature, pressure, proportion of components are calculated. An optimized working condition is given.
1993,
05: 498-504.
Abstract:
First of all the red fluorescence in COIL cavity is discovered by S. Yoshida in 1989. Owing to its possibility in developing a visible laser, the intensive studies of red fluoescence have been down by a few research groups. It is clear now that the fluorescence both in visible and near -IR range are the emission of CuCl2 in different excited state.
First of all the red fluorescence in COIL cavity is discovered by S. Yoshida in 1989. Owing to its possibility in developing a visible laser, the intensive studies of red fluoescence have been down by a few research groups. It is clear now that the fluorescence both in visible and near -IR range are the emission of CuCl2 in different excited state.
1993,
05: 505-508.
Abstract:
An one hundred joule KrF excimer laser was built in our institute in 1990. The maximum of output energy reaches 106 joules. This paper introduces the selection of the main structure parameters of the laser cavity and laser experiments.
An one hundred joule KrF excimer laser was built in our institute in 1990. The maximum of output energy reaches 106 joules. This paper introduces the selection of the main structure parameters of the laser cavity and laser experiments.
1993,
05: 509-520.
Abstract:
Simulations of kinetics in the laser cavity with electron-beam-pumping, also processes of laser production, amplification and transport in different injected fluxes and different inject time are presented. The one-dimensional approximation is used for the practical unstable resonator, and the transport equation is numerically integrated with the predictor -corrector method. The result shows that the quality of laser output is obviously improved with injected seed signal and the spontaneous emission is obviously. This simulation also demonstrates the spectral characteristic, the energy, and various efficiencies of the laser output. We also find that the injected time of the best locking efficiency is that moment when the small signal gain reaches the maximum value. The theoretical calculation of the laser output is in agreement with experiment of the parallel cavity and unstable resonator in different conditions.
Simulations of kinetics in the laser cavity with electron-beam-pumping, also processes of laser production, amplification and transport in different injected fluxes and different inject time are presented. The one-dimensional approximation is used for the practical unstable resonator, and the transport equation is numerically integrated with the predictor -corrector method. The result shows that the quality of laser output is obviously improved with injected seed signal and the spontaneous emission is obviously. This simulation also demonstrates the spectral characteristic, the energy, and various efficiencies of the laser output. We also find that the injected time of the best locking efficiency is that moment when the small signal gain reaches the maximum value. The theoretical calculation of the laser output is in agreement with experiment of the parallel cavity and unstable resonator in different conditions.
1993,
05: 521-526.
Abstract:
The experimental simulation results of instability of Stimulated Thermal Rayleigh Scattering (STRS) are reported in the paper, which include the studies on the process of instability of the sinusoidal perturbation source propagating in the thermal-blooming medium and the experimental studies on the increase of the small-scale thermal-blooming instability under different perturbation frequencies and different light power, and thus proves that the small-scale instability caused by thermal-blooming increases exponentially as laser propagation in the absorbing medium.
The experimental simulation results of instability of Stimulated Thermal Rayleigh Scattering (STRS) are reported in the paper, which include the studies on the process of instability of the sinusoidal perturbation source propagating in the thermal-blooming medium and the experimental studies on the increase of the small-scale thermal-blooming instability under different perturbation frequencies and different light power, and thus proves that the small-scale instability caused by thermal-blooming increases exponentially as laser propagation in the absorbing medium.
1993,
05: 527-532.
Abstract:
Through actual atmosphere, we have measured atmospheric transmittance for 1.315μm Iodine laser. With medium visibility, relative humidity 64% and 21℃, average value of atmospheric transmittance is 0.78. This result is fairly identical with computation value obtained by existing data and computer program.
Through actual atmosphere, we have measured atmospheric transmittance for 1.315μm Iodine laser. With medium visibility, relative humidity 64% and 21℃, average value of atmospheric transmittance is 0.78. This result is fairly identical with computation value obtained by existing data and computer program.
1993,
05: 533-539.
Abstract:
Laser beam propagation in the media with complex quadratic index of refraction n = n0 + n2r2/ re2 was investigated. The expressions of beam radius, W(z) and curvature of its wave front, R(z)-1 were obtained. The self-similar (s.s.) mode (perfect guiding) will occure after propagation distance larger than a characteristic length zc, only if n21≠0. The s.s. mode is a eigenmode of media, its propagation parameters W, R-1 are dependent on n2, but independent of the initial value W0, R0-1. At the end, s. s. mode is a Gaussian spherical wave, not the plane wave.
Laser beam propagation in the media with complex quadratic index of refraction n = n0 + n2r2/ re2 was investigated. The expressions of beam radius, W(z) and curvature of its wave front, R(z)-1 were obtained. The self-similar (s.s.) mode (perfect guiding) will occure after propagation distance larger than a characteristic length zc, only if n21≠0. The s.s. mode is a eigenmode of media, its propagation parameters W, R-1 are dependent on n2, but independent of the initial value W0, R0-1. At the end, s. s. mode is a Gaussian spherical wave, not the plane wave.
1993,
05: 540-544.
Abstract:
Thermal blooming induced by aerosol is discussed in laser beam propagation though atmosphere. We give the effective absorption coefficient αpff(t). Because of the limited conductivity of air, the increment of temperature of air heated by aerosol absorbing energy from laser beam is imhomogeneous, which lead to the αpff(t) dependent on time. The delay time tp, when the αpff(t)arrives at the maximum value, is dependent on the radius of aerosol.
Thermal blooming induced by aerosol is discussed in laser beam propagation though atmosphere. We give the effective absorption coefficient αpff(t). Because of the limited conductivity of air, the increment of temperature of air heated by aerosol absorbing energy from laser beam is imhomogeneous, which lead to the αpff(t) dependent on time. The delay time tp, when the αpff(t)arrives at the maximum value, is dependent on the radius of aerosol.
1993,
05: 545-550.
Abstract:
The linear analytic theory of small scale -size thermal blooming instabilities for a high energy laser propagating through a homogeneous medium is derived in paraxial scalar wave approximation and isobaric supposition. When we perform Fourier transforms in transversal coordinates and Laplace transforms in time and longitudinal coordinate, the fluctuations can be obtained in analytic form. In the real world the Fourier components of the fluctuations are written with the propagation kernal (or Green function) Kk (z,t), after the inverting Laplace transforms are performed.
The linear analytic theory of small scale -size thermal blooming instabilities for a high energy laser propagating through a homogeneous medium is derived in paraxial scalar wave approximation and isobaric supposition. When we perform Fourier transforms in transversal coordinates and Laplace transforms in time and longitudinal coordinate, the fluctuations can be obtained in analytic form. In the real world the Fourier components of the fluctuations are written with the propagation kernal (or Green function) Kk (z,t), after the inverting Laplace transforms are performed.
1993,
05: 551-556.
Abstract:
In this paper, anisoplanatism in adaptive optics and capability of phase derivative adaptive optics are analysed in time domain. The general formulas of residual phase structure function and Strehl ratio are obtained, which not only be used to discuss the anisoplanatism, but also can be used to analyse the other factors that degrade adaptive optics system performance, such as the mean wind velocity and the finite servo bandwidth of adaptive optics system. The results show that the capable scale of phase derivative adaptive optics are very narrow.
In this paper, anisoplanatism in adaptive optics and capability of phase derivative adaptive optics are analysed in time domain. The general formulas of residual phase structure function and Strehl ratio are obtained, which not only be used to discuss the anisoplanatism, but also can be used to analyse the other factors that degrade adaptive optics system performance, such as the mean wind velocity and the finite servo bandwidth of adaptive optics system. The results show that the capable scale of phase derivative adaptive optics are very narrow.
1993,
05: 557-563.
Abstract:
The double-pass amplification of Ne -like Ge soft X-ray laser was demonstrated by means of Mo/Si multi - layer reflective mirror. The output intensity of soft X-ray laser with reflective mirror was 40 times larger than that without reflective mirror and tended to be saturated when the total length of two following coupling targets was 28mm. The divergence angle of X-ray laser beam was decreased, the thickness of the gain region became smaller and the spatial coherence of X-ray laser beam was improved. The output intensities of X-ray laser with and without reflective mirror had no obvious difference when the total length of four series coupling targets was 56mm, which showed that the deep saturation of gain was reached.
The double-pass amplification of Ne -like Ge soft X-ray laser was demonstrated by means of Mo/Si multi - layer reflective mirror. The output intensity of soft X-ray laser with reflective mirror was 40 times larger than that without reflective mirror and tended to be saturated when the total length of two following coupling targets was 28mm. The divergence angle of X-ray laser beam was decreased, the thickness of the gain region became smaller and the spatial coherence of X-ray laser beam was improved. The output intensities of X-ray laser with and without reflective mirror had no obvious difference when the total length of four series coupling targets was 56mm, which showed that the deep saturation of gain was reached.
1993,
05: 564-574.
Abstract:
Based upon rate equations, the decay constant, population of excited states, inversion factor and small signal gain of Li-like Al recombination plasma as well as their relatonship with the electron temperature, and densit y, and escape probability of photons are discussed. The plasma state objective region which must be established for recombination Li-like Al X-ray lasers have been obtained. We also discussed the Z-scaling law of these physical quantities.
Based upon rate equations, the decay constant, population of excited states, inversion factor and small signal gain of Li-like Al recombination plasma as well as their relatonship with the electron temperature, and densit y, and escape probability of photons are discussed. The plasma state objective region which must be established for recombination Li-like Al X-ray lasers have been obtained. We also discussed the Z-scaling law of these physical quantities.
1993,
05: 575-580.
Abstract:
Some basic physical aspects about Hohlraum targets obtained in our experiment have been summarised this paper . The experimental scaling laws on energy absorption, x-ray conversion, suprathermal electron production and nonlinear process are given.
Some basic physical aspects about Hohlraum targets obtained in our experiment have been summarised this paper . The experimental scaling laws on energy absorption, x-ray conversion, suprathermal electron production and nonlinear process are given.
1993,
05: 581-584.
Abstract:
Based on PEL unified theory, we analysed the Coherent harmonic generation in an optical klystron and proposed a new method by which the output of coherent harmonic radiation can be increased by 30%.
Based on PEL unified theory, we analysed the Coherent harmonic generation in an optical klystron and proposed a new method by which the output of coherent harmonic radiation can be increased by 30%.
1993,
05: 585-588.
Abstract:
An active-passive colliding pulse mode-locked Nd: glass laser oscillator has been developed successfully. The pulse duration is 3ps with little fluctuation, and the amplitude stability of the peak pulse is better than ±6%. Some properties of the oscillator have also been investigated experimentally.
An active-passive colliding pulse mode-locked Nd: glass laser oscillator has been developed successfully. The pulse duration is 3ps with little fluctuation, and the amplitude stability of the peak pulse is better than ±6%. Some properties of the oscillator have also been investigated experimentally.
1993,
05: 589-594.
Abstract:
From the experiments on laser induced copper plasma, we obtained that for automatic matched-line photopumped Ne-like Cu, population inversion can be achieved if conditions of the pump source and the lasing medium are reasonable, and observable laser gain relies on whether the geomety of two laser-induced plasmas and the pumping laser irradiance are optimal.
From the experiments on laser induced copper plasma, we obtained that for automatic matched-line photopumped Ne-like Cu, population inversion can be achieved if conditions of the pump source and the lasing medium are reasonable, and observable laser gain relies on whether the geomety of two laser-induced plasmas and the pumping laser irradiance are optimal.
1993,
05: 595-600.
Abstract:
This measurement of radiation temperature space distribution for cavity plasma are performed with the foil-absorbing method. The principle of the method is described. This characteristics of the temperature distribution are given.
This measurement of radiation temperature space distribution for cavity plasma are performed with the foil-absorbing method. The principle of the method is described. This characteristics of the temperature distribution are given.
1993,
05: 601-607.
Abstract:
The verification of testing power of ground-based high power laser is an important physical problem in arms control. In this paper we propose a scheme to measure the scattering light of laser beam in atmosphere by multi-detector. The optimal detective parameters are calculated and several algorisms to evaluate the laser power are studied.
The verification of testing power of ground-based high power laser is an important physical problem in arms control. In this paper we propose a scheme to measure the scattering light of laser beam in atmosphere by multi-detector. The optimal detective parameters are calculated and several algorisms to evaluate the laser power are studied.
1993,
05: 608-614.
Abstract:
The electron back bombardment in the SW linacs with higher accelerating gradient is a undesirable phenomenon which will cause overheat of the electron gun cathode and destruction of the electron optics. The influences of the longitudinal motion on the electron back bombardment in SW linacs have been analysed by the same authors[1]. In this paper, the influ ences of the transverse motion on the electron back bamardment in SW linacs have been analysed by solving the beam envelope equations under backward motion. It is indicated that owing to the transverse motion under the backward motion, only part of the backward electrons can strike right on the cathode surface, the other part will strike on the inner walls of the cavity and beam hole. The definitions with their calculating methods of the back bombardment parameters such as back bombardment ratio, back bombardment current, back bombardment power are presented.
The electron back bombardment in the SW linacs with higher accelerating gradient is a undesirable phenomenon which will cause overheat of the electron gun cathode and destruction of the electron optics. The influences of the longitudinal motion on the electron back bombardment in SW linacs have been analysed by the same authors[1]. In this paper, the influ ences of the transverse motion on the electron back bamardment in SW linacs have been analysed by solving the beam envelope equations under backward motion. It is indicated that owing to the transverse motion under the backward motion, only part of the backward electrons can strike right on the cathode surface, the other part will strike on the inner walls of the cavity and beam hole. The definitions with their calculating methods of the back bombardment parameters such as back bombardment ratio, back bombardment current, back bombardment power are presented.
1993,
05: 615-622.
Abstract:
The vaporizalon characteristic and the vapor cval ution process of metallic targets irradiated by pulse laser beams were investigated by high speed schlieren diagonstic technique in this paper.The temperature of condensed phase transition, the front velocity of vapor plume and velocity of precursor shock wave in air of LYI2 aluminum targets were measured experimentally with different incident laser flux, and the temperature on the surface of condensed phase transition as a function of incident laser flux was obtained by approximatically analysis vaporization model.
The vaporizalon characteristic and the vapor cval ution process of metallic targets irradiated by pulse laser beams were investigated by high speed schlieren diagonstic technique in this paper.The temperature of condensed phase transition, the front velocity of vapor plume and velocity of precursor shock wave in air of LYI2 aluminum targets were measured experimentally with different incident laser flux, and the temperature on the surface of condensed phase transition as a function of incident laser flux was obtained by approximatically analysis vaporization model.
1993,
05: 623-628.
Abstract:
The nonlinear space charge effect of bunched beam in Hnac is one of the important reasons that induces the emittance growth because of the conversion of the field energy to kinetic energy. In this paper, we have worked out the internal field energies associated with some transverse nonuniform space charge distributions of a bunched beam, such as Gaussian distribution, waterbag distribution, and parabolic distribution. And the emittance growth caused by these nonuniformities are obtained.
The nonlinear space charge effect of bunched beam in Hnac is one of the important reasons that induces the emittance growth because of the conversion of the field energy to kinetic energy. In this paper, we have worked out the internal field energies associated with some transverse nonuniform space charge distributions of a bunched beam, such as Gaussian distribution, waterbag distribution, and parabolic distribution. And the emittance growth caused by these nonuniformities are obtained.
1993,
05: 629-632.
Abstract:
A compact structure, easily using Faraday cup was designed and tested for measuring electron beam which is less than 50kA with energy less than 0.8MeV. The method of calibrating was described and the risetime was found less than 6ns. The cup has been used to measure transmitted beam currents in the Cerenkov free electron laser experiment.
A compact structure, easily using Faraday cup was designed and tested for measuring electron beam which is less than 50kA with energy less than 0.8MeV. The method of calibrating was described and the risetime was found less than 6ns. The cup has been used to measure transmitted beam currents in the Cerenkov free electron laser experiment.
