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RSS2000 Vol. 12, No. 05
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2000,
12.
Abstract:
This paper analyzed the nonlinear relationship between the peak power of the output and the gain coefficient of the B-class CO2 laser with experimental and theoretic methods. The results show that when the modulating velocity nearly equals to the rate of transition between the rotation levels , the peak power of the output laser will be saturated at a gain coefficient point. This is the very specialize character of the B-class CO2 laser, the result of our experiment agreed with that of simulations well.
This paper analyzed the nonlinear relationship between the peak power of the output and the gain coefficient of the B-class CO2 laser with experimental and theoretic methods. The results show that when the modulating velocity nearly equals to the rate of transition between the rotation levels , the peak power of the output laser will be saturated at a gain coefficient point. This is the very specialize character of the B-class CO2 laser, the result of our experiment agreed with that of simulations well.
2000,
12.
Abstract:
When ultra-short laser pulses propagate in air, the plasma channel would be formed by the modulation of tunnel-ionization. In this paper, the resistivity of the plasma channel was evaluated and analyzed. It was found that the threshold intensity to create plasma channels is about 1014W/cm2. The required energy is small, so that laser beam can propagate very long distance.
When ultra-short laser pulses propagate in air, the plasma channel would be formed by the modulation of tunnel-ionization. In this paper, the resistivity of the plasma channel was evaluated and analyzed. It was found that the threshold intensity to create plasma channels is about 1014W/cm2. The required energy is small, so that laser beam can propagate very long distance.
2000,
12.
Abstract:
Small-scale ripples in intense laser beams caused by intensity or phase modulations will grow fast due to self-focusing effect after passing through the nonlinear media. This lead to the change of the intensity distribution in the beam and can cause media damage by filamentations when the nonlinear phase retardation(B integral) reach to the restriction value which partly depends on the primary ripple level. The certain D B restriction of laser system was obtained by numerical simulations which were coincidence with experiments on beam propagation in a rod Nd3+:glass.
Small-scale ripples in intense laser beams caused by intensity or phase modulations will grow fast due to self-focusing effect after passing through the nonlinear media. This lead to the change of the intensity distribution in the beam and can cause media damage by filamentations when the nonlinear phase retardation(B integral) reach to the restriction value which partly depends on the primary ripple level. The certain D B restriction of laser system was obtained by numerical simulations which were coincidence with experiments on beam propagation in a rod Nd3+:glass.
2000,
12.
Abstract:
It is a prospective technical route to generative UV coherent radiation using external high-power laser to pre-bunch ultra-relativistic electron beam provided by storage ring and then amplifying its harmonic components with the super-radiation method. Under the electron energy modulation and density modulation, the harmonic Super-radiation output power components in optical klystron is presented in this paper.
It is a prospective technical route to generative UV coherent radiation using external high-power laser to pre-bunch ultra-relativistic electron beam provided by storage ring and then amplifying its harmonic components with the super-radiation method. Under the electron energy modulation and density modulation, the harmonic Super-radiation output power components in optical klystron is presented in this paper.
2000,
12.
Abstract:
The package technique of high duty cycle, high power linear array diode laser is studied and the measured results of the laser performance are presented. Over 40W peak power output at duty cycles up to 20%(200m s，1000Hz) is achieved. At 100Hz to 1000Hz repeat frequency, the center wavelength is 805 ~ 808ns with corresponding spectral width of 3.1 ~ 4.2nm. The instability of the output laser is less than 1%.
The package technique of high duty cycle, high power linear array diode laser is studied and the measured results of the laser performance are presented. Over 40W peak power output at duty cycles up to 20%(200m s，1000Hz) is achieved. At 100Hz to 1000Hz repeat frequency, the center wavelength is 805 ~ 808ns with corresponding spectral width of 3.1 ~ 4.2nm. The instability of the output laser is less than 1%.
2000,
12.
Abstract:
Soft X-ray projection lithography is expected as a candidate for VLSI production in the near future. Based on such background, soft X-ray projection lithography (SXPL) technology is being extensively studied in several countries, especially in Japan and USA, which are the main offers of microelectronic integrated circuits and its fabrication facilities. Those researches have made important progress in the major areas of SXPL, like debris free laser produced plasma source, design of high resolution and large field projection system, super precision mirror/substrate polishing and coating, low defect reflective masks, surface-imaging resist, and super fine scan stage, etc. Along the same thought, therefore, the authors and their colleagues have concentrated in SXPL researches in the recent ye
Soft X-ray projection lithography is expected as a candidate for VLSI production in the near future. Based on such background, soft X-ray projection lithography (SXPL) technology is being extensively studied in several countries, especially in Japan and USA, which are the main offers of microelectronic integrated circuits and its fabrication facilities. Those researches have made important progress in the major areas of SXPL, like debris free laser produced plasma source, design of high resolution and large field projection system, super precision mirror/substrate polishing and coating, low defect reflective masks, surface-imaging resist, and super fine scan stage, etc. Along the same thought, therefore, the authors and their colleagues have concentrated in SXPL researches in the recent ye
2000,
12.
Abstract:
Numerical simulation of photolytic excitation and lasing on XeF(C-A) pumped by surface discharges is described. The effect from particle species, gaseous temperature and intracavity loss coefficient, optical coupling,and XeF2 pressure is analyzed and the theoretical results are in good agreement with the experimental data.
Numerical simulation of photolytic excitation and lasing on XeF(C-A) pumped by surface discharges is described. The effect from particle species, gaseous temperature and intracavity loss coefficient, optical coupling,and XeF2 pressure is analyzed and the theoretical results are in good agreement with the experimental data.
2000,
12.
Abstract:
In this paper, a kind of telecommunication network of atmospheric parameter remote sense was introduced. It can provide temperature, humidity, wind velocity and wind direction at several stations. It can be used in the study of atmospheric optics, atmospheric boundary and atmospheric environment and some other areas. At last some results were analyzed.
In this paper, a kind of telecommunication network of atmospheric parameter remote sense was introduced. It can provide temperature, humidity, wind velocity and wind direction at several stations. It can be used in the study of atmospheric optics, atmospheric boundary and atmospheric environment and some other areas. At last some results were analyzed.
2000,
12.
Abstract:
The 3D magnetic field is calculated and analyzed using normalized dimensions for PPM undulator. The 3D modify and the effect on the good field region of the magnet pole width are discussed for general case. The modify curve of the magnet pole width to the usually 2D approximation and the field transverse variation curve for various magnet pole widths are given
The 3D magnetic field is calculated and analyzed using normalized dimensions for PPM undulator. The 3D modify and the effect on the good field region of the magnet pole width are discussed for general case. The modify curve of the magnet pole width to the usually 2D approximation and the field transverse variation curve for various magnet pole widths are given
2000,
12.
Abstract:
Response of X-ray charge coupled device (CCD) to soft x rays were calibrated on Beijing Synchrotron Radiation Facility, and the experimental results have been obtained in photon energy range of 150eV to 1500eV. Then, a simple model was developed to simulate the calibrated results. The effect of CCD surface contamination on CCD response to x rays has also been investigated.
Response of X-ray charge coupled device (CCD) to soft x rays were calibrated on Beijing Synchrotron Radiation Facility, and the experimental results have been obtained in photon energy range of 150eV to 1500eV. Then, a simple model was developed to simulate the calibrated results. The effect of CCD surface contamination on CCD response to x rays has also been investigated.
2000,
12.
Abstract:
In this paper, the steady time of CxH1-x film, the density of the surface dangling band and the localization of the surface electronic state under the different H2 flow rate and the different in-situ treatment time of H+ were investigated. The effective method with which the surface dangling band density is decreased is the long H+ treatment time in-situ.
In this paper, the steady time of CxH1-x film, the density of the surface dangling band and the localization of the surface electronic state under the different H2 flow rate and the different in-situ treatment time of H+ were investigated. The effective method with which the surface dangling band density is decreased is the long H+ treatment time in-situ.
2000,
12.
Abstract:
Time-integrated spectra of three-halves harmonic emission from Au-disk irradiated by 1.053m m laser are experimentally studied. The wavelength shifts of red-shifted peak of the harmonic emission are measured in different angles. Fitting the experimental results to Barr's and Giulietti's theory shows that both theories can predict the correct dependence of the wavelength shift on the cosine of the emission angle while the former underestimates the electron temperature, and the later gives a result more close to that measured by x-ray.
Time-integrated spectra of three-halves harmonic emission from Au-disk irradiated by 1.053m m laser are experimentally studied. The wavelength shifts of red-shifted peak of the harmonic emission are measured in different angles. Fitting the experimental results to Barr's and Giulietti's theory shows that both theories can predict the correct dependence of the wavelength shift on the cosine of the emission angle while the former underestimates the electron temperature, and the later gives a result more close to that measured by x-ray.
2000,
12.
Abstract:
Cylindrical implosion is of great interest because of its excellent diagnostic access. We present one-dimensional numerical simulations to explore the plasma conditions that may be achieved. Combined with the numerical data, the development of Rayleigh-Taylor instabilities and Richtmyer-Meshkov instabilities in those targets are estimated. We found that it is possible to achieve a high density and temperature plasma with a relatively low temperature and density gradient using a cylindrical implosion directly-driven by a high-power laser.
Cylindrical implosion is of great interest because of its excellent diagnostic access. We present one-dimensional numerical simulations to explore the plasma conditions that may be achieved. Combined with the numerical data, the development of Rayleigh-Taylor instabilities and Richtmyer-Meshkov instabilities in those targets are estimated. We found that it is possible to achieve a high density and temperature plasma with a relatively low temperature and density gradient using a cylindrical implosion directly-driven by a high-power laser.
2000,
12.
Abstract:
The interaction of ultrahigh intensity laser with overdense plasma is studied using a 2.5D particle simulation code. A channel is formed due to the extremely large ponderomotive force associated with laser pulse. Strong self-generated magnetic fields produced by strong flow of high-energy electrons are observed. Three kinds of spatial profiles of laser intensity are used to investigate the effect of laser spatial profile on boring , and it is found that the boring effect is stronger when the radial gradient of laser intensity is bigger. Odd and even harmonics are found in reflected waves.
The interaction of ultrahigh intensity laser with overdense plasma is studied using a 2.5D particle simulation code. A channel is formed due to the extremely large ponderomotive force associated with laser pulse. Strong self-generated magnetic fields produced by strong flow of high-energy electrons are observed. Three kinds of spatial profiles of laser intensity are used to investigate the effect of laser spatial profile on boring , and it is found that the boring effect is stronger when the radial gradient of laser intensity is bigger. Odd and even harmonics are found in reflected waves.
2000,
12.
Abstract:
Two mechanisms of vacuole formation in microencapsulated microshells wall are introduced. It is verified that phase separation of trace amount of water in the organic solvent is the most possible course of vacuole formation.
Two mechanisms of vacuole formation in microencapsulated microshells wall are introduced. It is verified that phase separation of trace amount of water in the organic solvent is the most possible course of vacuole formation.
2000,
12.
Abstract:
A new way to invert the emission spectrum of a soft X ray source from the experiment spectrum obtained by transmission grating was provided. Compared with the conventional method, the new way need not a cut-off wavelength. Theoretically, it seems more convinced. A classical data obtained from spectrum measured in experiment of ICF was processed with different way, content result was obtained.
A new way to invert the emission spectrum of a soft X ray source from the experiment spectrum obtained by transmission grating was provided. Compared with the conventional method, the new way need not a cut-off wavelength. Theoretically, it seems more convinced. A classical data obtained from spectrum measured in experiment of ICF was processed with different way, content result was obtained.
2000,
12.
Abstract:
Through measuring the characteristic X-ray for copper target of mass thickness 23m g/cm2, its K-shell ionization cross section was calculated. The method of thin target with thick substrate was used in the experiment. The influence of the electrons reflected from the substrate was corrected by means of a electron transport calculation. The multiple scattering effect for the copper target of mass thickness 23m g /cm2 is corrected by the EGS4 program of Monte Carlo techniques. This method is reported for first time.
Through measuring the characteristic X-ray for copper target of mass thickness 23m g/cm2, its K-shell ionization cross section was calculated. The method of thin target with thick substrate was used in the experiment. The influence of the electrons reflected from the substrate was corrected by means of a electron transport calculation. The multiple scattering effect for the copper target of mass thickness 23m g /cm2 is corrected by the EGS4 program of Monte Carlo techniques. This method is reported for first time.
2000,
12.
Abstract:
This paper analyses the mechanism which backstreaming ions are produced and the effect of backstreaming ions on focus of electron beams. The methods which control the effect of backstreaming ions are also given. The results show that if backstreaming ions are H+ or C+, they seriously affect the focus of electronic beams after H+ or C+ backstreams 60ns; if backstreaming ions are Ta+ or W+, they do almost not affect the focus of electronic beams when the beam pulse is short, but seriously destroy the effect of the beam focus when the beam pulse > 200ns.
This paper analyses the mechanism which backstreaming ions are produced and the effect of backstreaming ions on focus of electron beams. The methods which control the effect of backstreaming ions are also given. The results show that if backstreaming ions are H+ or C+, they seriously affect the focus of electronic beams after H+ or C+ backstreams 60ns; if backstreaming ions are Ta+ or W+, they do almost not affect the focus of electronic beams when the beam pulse is short, but seriously destroy the effect of the beam focus when the beam pulse > 200ns.
2000,
12.
Abstract:
Using a ray-tracing code, we have designed a flat-field grazing-incidence spectrometer with 155mm incident distance. This is different from the conventional design for a flat-field grazing-incidence spectrometer. This spectrometer has good spectral resolution as well as smaller size and improved flexibility. The spectrum covers wavelenth ranges of 4nm-40nm and the spectral resolution is 0.01nm.
Using a ray-tracing code, we have designed a flat-field grazing-incidence spectrometer with 155mm incident distance. This is different from the conventional design for a flat-field grazing-incidence spectrometer. This spectrometer has good spectral resolution as well as smaller size and improved flexibility. The spectrum covers wavelenth ranges of 4nm-40nm and the spectral resolution is 0.01nm.
2000,
12.
Abstract:
A two-dimensional electromagnetic PIC particle simulation code in cylindrical mesh, with r- and z-coordinate dependence, has been simply introduced. The code is used to study penetration of the magnetic field in plasma of PEOS. For different boundary, the behaviors of magnetic field are found ,the reasonable explanations are given by physical analysis.
A two-dimensional electromagnetic PIC particle simulation code in cylindrical mesh, with r- and z-coordinate dependence, has been simply introduced. The code is used to study penetration of the magnetic field in plasma of PEOS. For different boundary, the behaviors of magnetic field are found ,the reasonable explanations are given by physical analysis.
2000,
12.
Abstract:
In Hefei synchrotron radiation Light source(HLS), The energy of injected electron beam is 200MeV, which is 1/4 of the storage ring energy. A compact injection scheme will be adopted after the upgrading of HLS. Based on the upgraded machine, this paper looks into the possibilities and schemes of injecting 800MeV electron beam into the storage ring.
In Hefei synchrotron radiation Light source(HLS), The energy of injected electron beam is 200MeV, which is 1/4 of the storage ring energy. A compact injection scheme will be adopted after the upgrading of HLS. Based on the upgraded machine, this paper looks into the possibilities and schemes of injecting 800MeV electron beam into the storage ring.
2000,
12.
Abstract:
The principle to control and suppress the corkscrew movement of beam centroid is represented in this paper. The formulae for magnetic fields induced by the cosine (cos) coil and sine (sin) coil are given. The results of two types of the coil-arrangement design are compared with each other. It is pointed out that the cos or sin coil designed in a more exact method can turn the steering field more effectively than that in a simple method.
The principle to control and suppress the corkscrew movement of beam centroid is represented in this paper. The formulae for magnetic fields induced by the cosine (cos) coil and sine (sin) coil are given. The results of two types of the coil-arrangement design are compared with each other. It is pointed out that the cos or sin coil designed in a more exact method can turn the steering field more effectively than that in a simple method.
2000,
12.
Abstract:
Ar4+ ions from ECR ion source are speed up a nd peel off with Lanzhou Heavy Ions Accelerator, so Ar8＋ ions with energy 93.8 MeV are obtained. According to atom data calculated by the expanded full r elativistic multiconfiguration Dirac-Fock(GRASP) code, we have distinguished and analysed those spectrams.
Ar4+ ions from ECR ion source are speed up a nd peel off with Lanzhou Heavy Ions Accelerator, so Ar8＋ ions with energy 93.8 MeV are obtained. According to atom data calculated by the expanded full r elativistic multiconfiguration Dirac-Fock(GRASP) code, we have distinguished and analysed those spectrams.
2000,
12.
Abstract:
The ions trapped by beam potential well can cause beam instability in electron storage rings. It is important to study the mechanism and suppress method of the instability to increase the perform level of machine. In this paper, the simulation methods and results of ion-trapping instability using strong-strong model were introduced for the HLS ring. These results can be used to understand the phenomena observed in the HLS ring.
The ions trapped by beam potential well can cause beam instability in electron storage rings. It is important to study the mechanism and suppress method of the instability to increase the perform level of machine. In this paper, the simulation methods and results of ion-trapping instability using strong-strong model were introduced for the HLS ring. These results can be used to understand the phenomena observed in the HLS ring.
2000,
12.
Abstract:
Because of quadrupoles rotation errors and vertical orbit distortions in sextupoles, it will induce the coupling of the horizontal and vertical directions, and the coupling is 12% (measurement result). The skew quadruples will be installed for horizontal-vertical coupling correction in HLS. The installation method is studied in the paper.
Because of quadrupoles rotation errors and vertical orbit distortions in sextupoles, it will induce the coupling of the horizontal and vertical directions, and the coupling is 12% (measurement result). The skew quadruples will be installed for horizontal-vertical coupling correction in HLS. The installation method is studied in the paper.
2000,
12.
Abstract:
A Repetitive Tesla-type Relativistic Electron Beam Accelerator was constructed and tested. A Tesla transformer with air core was adopted in the accelerator for charging of oil-filled Blumlein transmission line. The diode with flat cathode and meter foil anode was constructed. The main switch of the accelerator is a self-breakdown oil spark gap. Preliminary experiments were performed under rep-rate 0.2 Hz and 1 Hz. At 0.2 Hz, Relativistic Electron Beam Accelerator continuously operated for over than 70 shots. The voltage amplitude of diode of 300 kV, the pulse width (FWHM) of 30 ns and the rise-time of 5 ns were obtained.
A Repetitive Tesla-type Relativistic Electron Beam Accelerator was constructed and tested. A Tesla transformer with air core was adopted in the accelerator for charging of oil-filled Blumlein transmission line. The diode with flat cathode and meter foil anode was constructed. The main switch of the accelerator is a self-breakdown oil spark gap. Preliminary experiments were performed under rep-rate 0.2 Hz and 1 Hz. At 0.2 Hz, Relativistic Electron Beam Accelerator continuously operated for over than 70 shots. The voltage amplitude of diode of 300 kV, the pulse width (FWHM) of 30 ns and the rise-time of 5 ns were obtained.
2000,
12.
Abstract:
Based on Poincare-Lyapunov theorem and using qualitative analysis, we propose nonlinear feedback functions to realize control of beam halo-chaos. The controllers can force to counteract the effect of space charge, which lead to scatter and halo of proton beam according to theoretical analysis of beam matrix transport theory. The simulation results by the Particle in Cell (PIC) program show that beam halo-chaos is controlled effectively using nonlinear feedback control methods. This approach is believed to be practical for experiments.
Based on Poincare-Lyapunov theorem and using qualitative analysis, we propose nonlinear feedback functions to realize control of beam halo-chaos. The controllers can force to counteract the effect of space charge, which lead to scatter and halo of proton beam according to theoretical analysis of beam matrix transport theory. The simulation results by the Particle in Cell (PIC) program show that beam halo-chaos is controlled effectively using nonlinear feedback control methods. This approach is believed to be practical for experiments.
2000,
12.
Abstract:
The paper describes several photoelectric effect photon beam position monitors used in synchrotron radiation light source. Their main performances (e.g. sensitivity, position offset and linearity range) are analyzed and compared. The computed results are given. A new improved area-type monitor is presented.
The paper describes several photoelectric effect photon beam position monitors used in synchrotron radiation light source. Their main performances (e.g. sensitivity, position offset and linearity range) are analyzed and compared. The computed results are given. A new improved area-type monitor is presented.
2000,
12.
Abstract:
To get the reference data of the parameters for Hefei electron storage ring rebuilt，and to look for the physics problem of the storage ring, the characteristic parameters of the storage ring were measured for the first time. They are momentum compaction factor, dispersion functions, natural chromaticities, corrected chromaticities and central frequency.
To get the reference data of the parameters for Hefei electron storage ring rebuilt，and to look for the physics problem of the storage ring, the characteristic parameters of the storage ring were measured for the first time. They are momentum compaction factor, dispersion functions, natural chromaticities, corrected chromaticities and central frequency.
2000,
12.
Abstract:
Using a 2.5D fully electromagnetic particle-in-cell (PIC) code a new type of the high power microwave oscillator using tapered slow-wave structures structures have been simulated in this paper. This devices use not external magnetic field. This devices will have a power output of about 1.0 ~10 GW, the frequency of microwave f =1.6 ~ 12GHz if changing the parameter of the devices.
Using a 2.5D fully electromagnetic particle-in-cell (PIC) code a new type of the high power microwave oscillator using tapered slow-wave structures structures have been simulated in this paper. This devices use not external magnetic field. This devices will have a power output of about 1.0 ~10 GW, the frequency of microwave f =1.6 ~ 12GHz if changing the parameter of the devices.
2000,
12.
Abstract:
Based on the wavelet transform and its multiscale decompositions, we will construct a kind of wavelet energy accumulator, by which the energy on decomposition all different scales. As an application, an algorithm is developed that weak signal detection on wavelet energy accumulation. In this paper, we design a piece of simulation program and do many of radar signal detection simulation experiments with pulse and different simulation conditions (on the background of white noise and color noise). Simulation results indicate that weak signal detection is very successful depending on wavelet energy accumulation.
Based on the wavelet transform and its multiscale decompositions, we will construct a kind of wavelet energy accumulator, by which the energy on decomposition all different scales. As an application, an algorithm is developed that weak signal detection on wavelet energy accumulation. In this paper, we design a piece of simulation program and do many of radar signal detection simulation experiments with pulse and different simulation conditions (on the background of white noise and color noise). Simulation results indicate that weak signal detection is very successful depending on wavelet energy accumulation.
