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RSS2002 Vol. 14, No. 03
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2002,
14.
Abstract:
This paper presents the triggering property of SF6-N2 mixtures triggered by a quadrupled Nd:YAG laser. The delay and jitter increased as the pressure and the percentage of SF6 in SF6-N2 mixtures increased. The working ratio followed the same rule. The delay, jitter and the working ratio decreased as the wavelength of laser decreased when t he mixing ratio, pressure and charging voltage kept constant. The delay and jitter of SF6-N2 mixtures decreased as the focus length decreased. The better mixing ratio of SF6-N2 mixtures used as switching media should be 5%～45%(SF6) if the dependence the dielectric strength and the delay, jitter on the percentage of SF6 in SF6-N2 mixtures is nonlinear.
This paper presents the triggering property of SF6-N2 mixtures triggered by a quadrupled Nd:YAG laser. The delay and jitter increased as the pressure and the percentage of SF6 in SF6-N2 mixtures increased. The working ratio followed the same rule. The delay, jitter and the working ratio decreased as the wavelength of laser decreased when t he mixing ratio, pressure and charging voltage kept constant. The delay and jitter of SF6-N2 mixtures decreased as the focus length decreased. The better mixing ratio of SF6-N2 mixtures used as switching media should be 5%～45%(SF6) if the dependence the dielectric strength and the delay, jitter on the percentage of SF6 in SF6-N2 mixtures is nonlinear.
2002,
14.
Abstract:
For a particular pulsed-power generator, i.e., fixed pinch current as well as its rise time, the z-pinch load (initial radius r0 and line mass density m0 ) should be optimized to maximize the x-radiation. The radial density profile of the gas load produced by a supersonic nozzle used in gas puff z-pinch was measured with a miniature fast ionization gauge and it yields a line mass density of 43 μg/cm that is in agreement with the nozzle design.
For a particular pulsed-power generator, i.e., fixed pinch current as well as its rise time, the z-pinch load (initial radius r0 and line mass density m0 ) should be optimized to maximize the x-radiation. The radial density profile of the gas load produced by a supersonic nozzle used in gas puff z-pinch was measured with a miniature fast ionization gauge and it yields a line mass density of 43 μg/cm that is in agreement with the nozzle design.
2002,
14.
Abstract:
The effects of electron flux on the optical properties of ZnO/K2SiO3 thermal control coating are studied. Th e test specimens were exposed to electrons at a flux of 5×1011/cm2·s，8×1011/cm2·s，1×1012/cm2·s and 5×1012/cm2·s, respectively . The irradiation caused an optical degradation of the coatings. And an air bleaching phenomenon of the degraded coatings was observed. Mechanisms for optical degradation of ZnO/K2SiO3 thermal control coating are analyzed. The influence of electron flux on solar absorptance is also discussed. It is found that in the electron flux range of 5×1011 to 1×1012/cm2·s, there are no different electron flux effects on the optical properties of ZnO/K2SiO3 thermal control coating. Accordingly, in this range the accelerated ground-based testing to simulate e
The effects of electron flux on the optical properties of ZnO/K2SiO3 thermal control coating are studied. Th e test specimens were exposed to electrons at a flux of 5×1011/cm2·s，8×1011/cm2·s，1×1012/cm2·s and 5×1012/cm2·s, respectively . The irradiation caused an optical degradation of the coatings. And an air bleaching phenomenon of the degraded coatings was observed. Mechanisms for optical degradation of ZnO/K2SiO3 thermal control coating are analyzed. The influence of electron flux on solar absorptance is also discussed. It is found that in the electron flux range of 5×1011 to 1×1012/cm2·s, there are no different electron flux effects on the optical properties of ZnO/K2SiO3 thermal control coating. Accordingly, in this range the accelerated ground-based testing to simulate e
2002,
14.
Abstract:
A high-power laser beam illuminates a photocathode surface placed on an end wall of an RF cavity. The emitted electrons are accelerated immediately to a relativistic energy by the strong RF field in the cavity. But space charge effect induces beam emittance growth especially near the cathode where the electrons are still nonrelativistic. This paper analyzes the factors which lead the transverse emittance growth and method how t o resolve this problem. After introducing solenoidal focusing near the photocathode, the beam emittance growth is suppressed dramatically. The beam emittance is given also after compensation and simulation results. The measurements show the se results are coincident.
A high-power laser beam illuminates a photocathode surface placed on an end wall of an RF cavity. The emitted electrons are accelerated immediately to a relativistic energy by the strong RF field in the cavity. But space charge effect induces beam emittance growth especially near the cathode where the electrons are still nonrelativistic. This paper analyzes the factors which lead the transverse emittance growth and method how t o resolve this problem. After introducing solenoidal focusing near the photocathode, the beam emittance growth is suppressed dramatically. The beam emittance is given also after compensation and simulation results. The measurements show the se results are coincident.
2002,
14.
Abstract:
To obtain high average current electron beams for high average power Free Electron Laser (FEL), a DC-SC photocathode injector is designed. It consists of DC extraction gap, 1+1/2 superconducting cavity and coaxial input system. High quality electron beams of CW mode or high duty factor can be obtained. The optimization of the injector and simulation of beam dynamics have been done. Model cavity experiments showed the correctness of the simulation.
To obtain high average current electron beams for high average power Free Electron Laser (FEL), a DC-SC photocathode injector is designed. It consists of DC extraction gap, 1+1/2 superconducting cavity and coaxial input system. High quality electron beams of CW mode or high duty factor can be obtained. The optimization of the injector and simulation of beam dynamics have been done. Model cavity experiments showed the correctness of the simulation.
2002,
14.
Abstract:
Aiming at the technical request of high power injector, we designed two Nylon radial graded insulation supports on the heads of cathode and anode of the existing 2MeV injector. The experiment results showed that, on the basis of credible insulation, the supports improved the quality of coaxality between the cathode and the anode, ameliorated the identity of the three axes of beams, magnetic field and mechanism, and settled the groundwork for advancing each technical performances of the 2MeV injector.
Aiming at the technical request of high power injector, we designed two Nylon radial graded insulation supports on the heads of cathode and anode of the existing 2MeV injector. The experiment results showed that, on the basis of credible insulation, the supports improved the quality of coaxality between the cathode and the anode, ameliorated the identity of the three axes of beams, magnetic field and mechanism, and settled the groundwork for advancing each technical performances of the 2MeV injector.
2002,
14.
Abstract:
This paper presents the distinct characteristics of biaxial crystals caused by inherent stress using cone-shape d interference in the samples. The results of optical experiment show that the characteristics of light uniformity depend greatly on the concentrations of quaternary ammonium salt in solution. Supernormal transmittance ratio properties are reported of KDP crystals doped with 0.001% quaternary ammonium salt. These pheno mena show that the wave-plane effect and the optical activity are highly displayed in KDP crystals, and the effect varies with the three-dimensional positions.
This paper presents the distinct characteristics of biaxial crystals caused by inherent stress using cone-shape d interference in the samples. The results of optical experiment show that the characteristics of light uniformity depend greatly on the concentrations of quaternary ammonium salt in solution. Supernormal transmittance ratio properties are reported of KDP crystals doped with 0.001% quaternary ammonium salt. These pheno mena show that the wave-plane effect and the optical activity are highly displayed in KDP crystals, and the effect varies with the three-dimensional positions.
2002,
14.
Abstract:
The experimental studies of Ni-like Ag x-ray laser and plasma diagnosis by moiré deflection method were performed with ShenguangII laser facility. The saturated output of Ni-like Ag x-ray laser and the moiré deflectogram including the electron density information of the target plasma were obtained.
The experimental studies of Ni-like Ag x-ray laser and plasma diagnosis by moiré deflection method were performed with ShenguangII laser facility. The saturated output of Ni-like Ag x-ray laser and the moiré deflectogram including the electron density information of the target plasma were obtained.
2002,
14.
Abstract:
The periodic and non-periodic multilayers were designed by using a random number to change each layer of multilayers and a suitable merit function. Ion beam sputtering and magnetron sputtering were used to fabricate various multilayers including periodic, non-periodic multilayers and beam splitters in soft X-ray range. The characterization of multilayers by small angle x-ray diffraction, Auger electron spectroscopy, Rutherford back scattering spectroscopy and reflectivity illustrated the multilayers had good structures and smooth interlayers. The reflectivity and transmission of a beam splitter is about 5%. Filters is one of key components in X-ray laser experiments. The fabrication and transmission properties of Ag、Zr were studied. The Rutherford back scattering spectroscopy and Auger el
The periodic and non-periodic multilayers were designed by using a random number to change each layer of multilayers and a suitable merit function. Ion beam sputtering and magnetron sputtering were used to fabricate various multilayers including periodic, non-periodic multilayers and beam splitters in soft X-ray range. The characterization of multilayers by small angle x-ray diffraction, Auger electron spectroscopy, Rutherford back scattering spectroscopy and reflectivity illustrated the multilayers had good structures and smooth interlayers. The reflectivity and transmission of a beam splitter is about 5%. Filters is one of key components in X-ray laser experiments. The fabrication and transmission properties of Ag、Zr were studied. The Rutherford back scattering spectroscopy and Auger el
2002,
14.
Abstract:
This paper reports a theoretical method to calculate the resolved absorption spectra and emission spectra (optically thin) of hot dense plasmas. Due to its fully relativistic treatment incorporated with the quantum defect theory, it calculates the absorption spectra dn emission spectra for single element or multi-element plasmas with little computational efforts. The calculated absoption spectra of LTE gold plasmas agree well with the experimental ones. It also calculated the opticaliy thin emission spectra of LTE gold plasmas, which is helpful to diagnose the plasmas of relevant ICF plasmas. It can also provide the relevant paramenters such as populatin density of various ionic stages, precise radiative propties for ICF studies.
This paper reports a theoretical method to calculate the resolved absorption spectra and emission spectra (optically thin) of hot dense plasmas. Due to its fully relativistic treatment incorporated with the quantum defect theory, it calculates the absorption spectra dn emission spectra for single element or multi-element plasmas with little computational efforts. The calculated absoption spectra of LTE gold plasmas agree well with the experimental ones. It also calculated the opticaliy thin emission spectra of LTE gold plasmas, which is helpful to diagnose the plasmas of relevant ICF plasmas. It can also provide the relevant paramenters such as populatin density of various ionic stages, precise radiative propties for ICF studies.
2002,
14.
Abstract:
In this paper, the new discharge circuit of power conditioning system for high power laser is studied. The theoretical model of the main discharge circuit is established. The pre-ionization circuit is studied in experiment. In addition, the explosion energy of the new large xenon lamp is successfully measured. The conclusion of this paper has been applied to 4×2 amplifier system.
In this paper, the new discharge circuit of power conditioning system for high power laser is studied. The theoretical model of the main discharge circuit is established. The pre-ionization circuit is studied in experiment. In addition, the explosion energy of the new large xenon lamp is successfully measured. The conclusion of this paper has been applied to 4×2 amplifier system.
2002,
14.
Abstract:
The physical process to fabricate hollow glass microspheres(HGM) by the Liquid Droplet Method in a 7-meter-high multi-zone high temperature furnace has been modeled mathematically. And the model quantitatively describes the whole process, through which the main parameters of the droplets/membrane spheres/HGM including the velocity, the sizes, the glass-forming oxide mass, the wall-thicknesses, and the inner gas pressures of vapor and air inside can be calculated. Calculation has been done under a series of operation conditions, especially at different purge gas rates, initial concentrations of the blowing agent and those of glass-forming oxides in the glass-forming solutions, and sizes of the initial droplets. The calculated results are to some degree in good agreement with the experiments
The physical process to fabricate hollow glass microspheres(HGM) by the Liquid Droplet Method in a 7-meter-high multi-zone high temperature furnace has been modeled mathematically. And the model quantitatively describes the whole process, through which the main parameters of the droplets/membrane spheres/HGM including the velocity, the sizes, the glass-forming oxide mass, the wall-thicknesses, and the inner gas pressures of vapor and air inside can be calculated. Calculation has been done under a series of operation conditions, especially at different purge gas rates, initial concentrations of the blowing agent and those of glass-forming oxides in the glass-forming solutions, and sizes of the initial droplets. The calculated results are to some degree in good agreement with the experiments
2002,
14.
Abstract:
The X-ray radiation can be used in heating sandwich type tamped sample targets to produce a uniform plasmas, which is essential for absorption spectrum measurement experiments to provide mean ingful quantitative data on radiative and material properties. With 1D multi-gr oup radiation transport program, this paper studies the impact of those target's structure on the plasma states produced by X-ray heating. A CH layers tamped iron target is heated by X-ray from one side in our simulation. In order to prod uce a uniform plasma states at a moment, the scale of plasma produced must be shorter than the heat conducting distances, which determines the initial thickness of iron samples. The thickness of CH layer has obvious confining effect on the plasma expansion, it also affects the uniform pla
The X-ray radiation can be used in heating sandwich type tamped sample targets to produce a uniform plasmas, which is essential for absorption spectrum measurement experiments to provide mean ingful quantitative data on radiative and material properties. With 1D multi-gr oup radiation transport program, this paper studies the impact of those target's structure on the plasma states produced by X-ray heating. A CH layers tamped iron target is heated by X-ray from one side in our simulation. In order to prod uce a uniform plasma states at a moment, the scale of plasma produced must be shorter than the heat conducting distances, which determines the initial thickness of iron samples. The thickness of CH layer has obvious confining effect on the plasma expansion, it also affects the uniform pla
2002,
14.
Abstract:
SG-Ⅱlaser facility has recently been able to deliver 3w 0 (blue) light with the outer conversion efficiency of ≥60% during its routine operation. The pinhole injection experiment this year indicated the optical quality of the blue, especially the side lobe distribution, was even better than that of the red (1w 0). With the 100ps red light output, DT fuel exploding pusher experiment delivered the maximum neutron yields of 4×109 per shot. The red light line focus has led to the Ni like Ag X-ray laser's saturation and the successful observation of the Moire fringe deflection while the laser was applied to a separated laser plasmas. This paper presents the optical features of SG-Ⅱlaser facility and describes some of the experiments conducted on the facility.
SG-Ⅱlaser facility has recently been able to deliver 3w 0 (blue) light with the outer conversion efficiency of ≥60% during its routine operation. The pinhole injection experiment this year indicated the optical quality of the blue, especially the side lobe distribution, was even better than that of the red (1w 0). With the 100ps red light output, DT fuel exploding pusher experiment delivered the maximum neutron yields of 4×109 per shot. The red light line focus has led to the Ni like Ag X-ray laser's saturation and the successful observation of the Moire fringe deflection while the laser was applied to a separated laser plasmas. This paper presents the optical features of SG-Ⅱlaser facility and describes some of the experiments conducted on the facility.
2002,
14.
Abstract:
Partial coherence source is a key part in the laser system using echelon-free introduced spatial incoherence beam smoothing technique. Different kinds of partial coherence sources have been studied experimentally for improving the uniformity of laser intensity distribution. It is found that the source produced by excimer laser scattering on the surface of a teflon plate is ideal. The properties of this kind of source are studied. As a result, the uniformity of source beam intensity distribution, the beam spatial coherence and energy transfer efficiency of the source are obtained.
Partial coherence source is a key part in the laser system using echelon-free introduced spatial incoherence beam smoothing technique. Different kinds of partial coherence sources have been studied experimentally for improving the uniformity of laser intensity distribution. It is found that the source produced by excimer laser scattering on the surface of a teflon plate is ideal. The properties of this kind of source are studied. As a result, the uniformity of source beam intensity distribution, the beam spatial coherence and energy transfer efficiency of the source are obtained.
2002,
14.
Abstract:
Hard X-ray continuum generated from interaction of UV high intensity ultrashort pulse laser with solid target has been investigated by experiment. P-polarized light irradiate 5mm Cu slab with 45° ，the hard x-ray with energy of 200keV has been detected. Fitting the experiment data by Maxwellian distribution, the temperature of hot electron is 67keV. The experiment data is the results of combination of several absorption mechanisms.
Hard X-ray continuum generated from interaction of UV high intensity ultrashort pulse laser with solid target has been investigated by experiment. P-polarized light irradiate 5mm Cu slab with 45° ，the hard x-ray with energy of 200keV has been detected. Fitting the experiment data by Maxwellian distribution, the temperature of hot electron is 67keV. The experiment data is the results of combination of several absorption mechanisms.
2002,
14.
Abstract:
In this paper, it is supposed that there is a gap in the interface of two contacting steel plates due to thermal deformation under laser beam irradiation, and this gap will affect heat transfer in this interface obviously. This supposition is testified by experiments and simulation. This work is helpful to the study of the destruction mechanism under high power laser loading, and provides an effective way for anti-laser research .
In this paper, it is supposed that there is a gap in the interface of two contacting steel plates due to thermal deformation under laser beam irradiation, and this gap will affect heat transfer in this interface obviously. This supposition is testified by experiments and simulation. This work is helpful to the study of the destruction mechanism under high power laser loading, and provides an effective way for anti-laser research .
2002,
14.
Abstract:
Basic characters of digital holographic profiling including its system error, resolution, imaging depth, and the size lize limit of the recorded object are theoretically discussed in this papers. It is pointed out that the system error of digital holographic profiling is in proportion to the spuared size of he CCD chip and in inverse proportion to the recording distance. This paper also pointed out that the resolution of digital holographic profiling and the maximum size of the recorded object are all proportional to the size of CCD chip and in inverse proportion to the recording distance, while its imaging depth increases with the recording distance.
Basic characters of digital holographic profiling including its system error, resolution, imaging depth, and the size lize limit of the recorded object are theoretically discussed in this papers. It is pointed out that the system error of digital holographic profiling is in proportion to the spuared size of he CCD chip and in inverse proportion to the recording distance. This paper also pointed out that the resolution of digital holographic profiling and the maximum size of the recorded object are all proportional to the size of CCD chip and in inverse proportion to the recording distance, while its imaging depth increases with the recording distance.
2002,
14.
Abstract:
Laser conditioning is a process w here the damage threshold of the coating is increased or the damage created is minimized so that it does not grow upon further irradiation. It is feasible that the damage threshold be improved safely and the power density sustain by the laser system be stepped up by studying the mechanism and technology of laser conditioning systematically. From the changes of several sol-gel films and PVD films during laser conditioning, some damages occurred. The damages are correlated to defects of the film itself and the beam parameters. It is proved that laser conditioning can eliminate film defects step to step.
Laser conditioning is a process w here the damage threshold of the coating is increased or the damage created is minimized so that it does not grow upon further irradiation. It is feasible that the damage threshold be improved safely and the power density sustain by the laser system be stepped up by studying the mechanism and technology of laser conditioning systematically. From the changes of several sol-gel films and PVD films during laser conditioning, some damages occurred. The damages are correlated to defects of the film itself and the beam parameters. It is proved that laser conditioning can eliminate film defects step to step.
2002,
14.
Abstract:
A new family of solution of the non-paraxial wave equation that depicts the ultrashort pulsed light beam propagation in free space is given, of which the spatial transverse part is Bessel function while the temporal profile can be arbitrary. Therefore the pulsed beam behaves like diffraction-free without any transverse spreading, while the temporal part changes as in the disperive medium, which is dominated by the so-called spatially induced group velocity dispersion (SIGVD).
A new family of solution of the non-paraxial wave equation that depicts the ultrashort pulsed light beam propagation in free space is given, of which the spatial transverse part is Bessel function while the temporal profile can be arbitrary. Therefore the pulsed beam behaves like diffraction-free without any transverse spreading, while the temporal part changes as in the disperive medium, which is dominated by the so-called spatially induced group velocity dispersion (SIGVD).
2002,
14.
Abstract:
Wavefront aberration caused by atmospheric turbulence weakens the capability of imaging optical system. Artificial beacon is used to correct the aberration successfully. An e xperimental beacon system and it's results are presented. The relations between the parameters of key components and measurement result are also analyzed.
Wavefront aberration caused by atmospheric turbulence weakens the capability of imaging optical system. Artificial beacon is used to correct the aberration successfully. An e xperimental beacon system and it's results are presented. The relations between the parameters of key components and measurement result are also analyzed.
2002,
14.
Abstract:
In this paper, a new method of laser beam combination by SBS is proposed. In this method, the pump pulse cluster, which consists of series pulses that is distributed by various time, is incident at one side while the Stokes seed is incident at the other side of the SBS cell, The Stokes seed beam extracts energy from the input pulse cluster in the interaction region of the SBS cell. Energy reflectivity and pulse width of the Stokes seed are calculated on condition of various pulse cluster, seed and medium. The results show that highly effective beam combination is obtained by back injecting Stokes seed into amplified SBS cell and the extracting energy from the pulse cluster of the pump.
In this paper, a new method of laser beam combination by SBS is proposed. In this method, the pump pulse cluster, which consists of series pulses that is distributed by various time, is incident at one side while the Stokes seed is incident at the other side of the SBS cell, The Stokes seed beam extracts energy from the input pulse cluster in the interaction region of the SBS cell. Energy reflectivity and pulse width of the Stokes seed are calculated on condition of various pulse cluster, seed and medium. The results show that highly effective beam combination is obtained by back injecting Stokes seed into amplified SBS cell and the extracting energy from the pulse cluster of the pump.
2002,
14.
Abstract:
A new kind of light beam generated from superposing cosh-Gaussian beams is proposed. Two types of superposing light field with different weight coefficients are disscussed in detail. It was found that the beam profiles have a nearly flat top but its sides reduce contiunously for suitable parameters. The beam may also be a solution of the paraxial wave equation for propagation in complex optical systems because the equation is linear. The propagation factor of cosh-Gaussian beams is calculated in this article.
A new kind of light beam generated from superposing cosh-Gaussian beams is proposed. Two types of superposing light field with different weight coefficients are disscussed in detail. It was found that the beam profiles have a nearly flat top but its sides reduce contiunously for suitable parameters. The beam may also be a solution of the paraxial wave equation for propagation in complex optical systems because the equation is linear. The propagation factor of cosh-Gaussian beams is calculated in this article.
2002,
14.
Abstract:
This paper describes a new method of pump-coupling. Ring-LD tightly surrounds YLF stick to accomplish directly coupled side-pumping, total pumping power is 3kW. Correspondingly ideal pumping light utilizing efficiency and pump-field distribution are obtained by this way. Maximal output at wavelength 1054nm is 1.01J, converting efficiency form light to light efficiency is more than 60%.
This paper describes a new method of pump-coupling. Ring-LD tightly surrounds YLF stick to accomplish directly coupled side-pumping, total pumping power is 3kW. Correspondingly ideal pumping light utilizing efficiency and pump-field distribution are obtained by this way. Maximal output at wavelength 1054nm is 1.01J, converting efficiency form light to light efficiency is more than 60%.
2002,
14.
Abstract:
Using the traditional technique to measure laser facula with a detector array, the array should be large enough if the facule has a large size, Thas large amount of detectors are needed which increase the cost. The design of rotational device of array detector makes it possible for measuring laser facula with high spatial resolution and low cost. The main idea is to rotate a linear array of detectors to carry out the facula measurement in the scanned area. The developing routine of the device and its measurement result is presented.
Using the traditional technique to measure laser facula with a detector array, the array should be large enough if the facule has a large size, Thas large amount of detectors are needed which increase the cost. The design of rotational device of array detector makes it possible for measuring laser facula with high spatial resolution and low cost. The main idea is to rotate a linear array of detectors to carry out the facula measurement in the scanned area. The developing routine of the device and its measurement result is presented.
2002,
14.
Abstract:
A large aperture discharge-pumped KrF laser module with simple spark gaps was developed. The laser beam cross section of 4cm×3cm and the maximum laser output energy of 1.3J in 20ns were obtained at the charging voltage of 30kV and gas mixtures of ［F2］∶［Kr］∶［Ne］= 0.1∶2∶97.9. The gain and absorption coefficients at different gas mixtures were measured with a frequency doubled dye laser pumped by a XeCl laser. Using this laser module as a ps amplifier, the output energy of 140mJ in 10ps was obtained.
A large aperture discharge-pumped KrF laser module with simple spark gaps was developed. The laser beam cross section of 4cm×3cm and the maximum laser output energy of 1.3J in 20ns were obtained at the charging voltage of 30kV and gas mixtures of ［F2］∶［Kr］∶［Ne］= 0.1∶2∶97.9. The gain and absorption coefficients at different gas mixtures were measured with a frequency doubled dye laser pumped by a XeCl laser. Using this laser module as a ps amplifier, the output energy of 140mJ in 10ps was obtained.
2002,
14.
Abstract:
The latest development of research on femtosecond nonlinear optics is introduced in this article. Recent progress in ultrafast optics has allowed the generation of ultraintense light pulses comprising merely a few field oscillation cycles. The arising intensity gradient allows electrons to survive in their bound atomic state up to external field strengths many times higher than the binding Coulomb field and gives rise to ionization rates comparable to the light frequency resulting in a significant extension of the frontiers of nonlinear optics and (nonrelativistic) high field physics. Implications include the generation of coherent harmonic radiation up to keV photon energies.
The latest development of research on femtosecond nonlinear optics is introduced in this article. Recent progress in ultrafast optics has allowed the generation of ultraintense light pulses comprising merely a few field oscillation cycles. The arising intensity gradient allows electrons to survive in their bound atomic state up to external field strengths many times higher than the binding Coulomb field and gives rise to ionization rates comparable to the light frequency resulting in a significant extension of the frontiers of nonlinear optics and (nonrelativistic) high field physics. Implications include the generation of coherent harmonic radiation up to keV photon energies.
2002,
14.
Abstract:
A chemical oxygen-iodine laser (COIL) with a square pipe-array jet-type singlet oxygen generator (SPJSOG)， an array of supersonic I2 – O2 mixing nozzles and nitrogen buffer gases was demonstrated in our laboratory. In our primary experimental stage, an output power of 1.8kw was obtained for a chlorine flowrate of 110mmol/s, corresponding to a chemical efficiency of 18%. The SPJSOG has shown great stabilities during operation in the case of no gas-liquid separator and cold trap. Although not optimized for the nitrogen buffer gas in our primary experimental stage, the COIL device has shown great potential to approach the performance of the COIL with helium buffer gases.
A chemical oxygen-iodine laser (COIL) with a square pipe-array jet-type singlet oxygen generator (SPJSOG)， an array of supersonic I2 – O2 mixing nozzles and nitrogen buffer gases was demonstrated in our laboratory. In our primary experimental stage, an output power of 1.8kw was obtained for a chlorine flowrate of 110mmol/s, corresponding to a chemical efficiency of 18%. The SPJSOG has shown great stabilities during operation in the case of no gas-liquid separator and cold trap. Although not optimized for the nitrogen buffer gas in our primary experimental stage, the COIL device has shown great potential to approach the performance of the COIL with helium buffer gases.
2002,
14.
Abstract:
This report presents the time-depended fully implicit LU algorithm, which was used to solve the Navier-Stokes equations with NND difference scheme in numerical simulation to the flowfields of supersonic diffuser in the pressure recovery system. The algebric turbulence model as used to simulate the complicated flowfileds, and the computational result was analyzed for more advanced work.
This report presents the time-depended fully implicit LU algorithm, which was used to solve the Navier-Stokes equations with NND difference scheme in numerical simulation to the flowfields of supersonic diffuser in the pressure recovery system. The algebric turbulence model as used to simulate the complicated flowfileds, and the computational result was analyzed for more advanced work.
2002,
14.
Abstract:
In this paper, the samplesurface, fracture surface and metallagraphic structure are examined by SEM of the loaded beams and plates irradiated by CW CO2 laser, and the influence of irradiation of high power laser in the material properties of LY12 is analysed then the reason and character of material failure by the thermal and mechanical force are investigated.
In this paper, the samplesurface, fracture surface and metallagraphic structure are examined by SEM of the loaded beams and plates irradiated by CW CO2 laser, and the influence of irradiation of high power laser in the material properties of LY12 is analysed then the reason and character of material failure by the thermal and mechanical force are investigated.
2002,
14.
Abstract:
In a COIL , the application of normal type virtual confocal and containing roof-top mirror fold unstable resonators are analyzed using simplified kinetics and gain medium model , from the calculation result , a conclusion can be drawn that containing roof-top mirror fold type is better than normal type in improving intensity distributing uniformity and output power of near-field .
In a COIL , the application of normal type virtual confocal and containing roof-top mirror fold unstable resonators are analyzed using simplified kinetics and gain medium model , from the calculation result , a conclusion can be drawn that containing roof-top mirror fold type is better than normal type in improving intensity distributing uniformity and output power of near-field .
2002,
14.
Abstract:
The stability of the free electron laser output is mainly determined by the stability of the electron beam, an d the stability of the electron beam based on RF linac is mainly determined by t he stability of the microwave source. To realize the saturation output of FEL an d to get better FEL spectrum purity, the amplitude and phase stability of RF power must be very high according to FEL theory. The FEL stability and its requirements on microwave stability are discussed, and the required parameters of microwave stability for CAEP FIR-FEL and BFEL are obtained.
The stability of the free electron laser output is mainly determined by the stability of the electron beam, an d the stability of the electron beam based on RF linac is mainly determined by t he stability of the microwave source. To realize the saturation output of FEL an d to get better FEL spectrum purity, the amplitude and phase stability of RF power must be very high according to FEL theory. The FEL stability and its requirements on microwave stability are discussed, and the required parameters of microwave stability for CAEP FIR-FEL and BFEL are obtained.
2002,
14.
Abstract:
An analysis method used for the double reentrant cavity of multiple-beam klystron is developed in this paper. According to the field equivalent principle, the equivalent model cavity is divided into two regular regions. The field of each region is stimulated by virtual surface magnetic current density on the common surface and ca n be expressed by integral of Green functions. The resonant frequency can be obtained by solving the field matching equation. With the HFSS field computation co de, the theoretical result is compared with the simulation one.
An analysis method used for the double reentrant cavity of multiple-beam klystron is developed in this paper. According to the field equivalent principle, the equivalent model cavity is divided into two regular regions. The field of each region is stimulated by virtual surface magnetic current density on the common surface and ca n be expressed by integral of Green functions. The resonant frequency can be obtained by solving the field matching equation. With the HFSS field computation co de, the theoretical result is compared with the simulation one.
2002,
14.
Abstract:
A6 relativistic magnetron`s resonated system is calculated and simulated by equivalent circuit and high frequency structure simulator (HFSS of Agilent), and the effect of end cap to resonated frequency is especially paid attention to in this paper. Results of simulation and cold test show that the end cap will cause resonated frequency to change and in some case, the end cap will result in that two different resonated frequencies satisfy the same resonated mode. It will make mode compete more acute and disadvantage to work of relativistic magnetron.
A6 relativistic magnetron`s resonated system is calculated and simulated by equivalent circuit and high frequency structure simulator (HFSS of Agilent), and the effect of end cap to resonated frequency is especially paid attention to in this paper. Results of simulation and cold test show that the end cap will cause resonated frequency to change and in some case, the end cap will result in that two different resonated frequencies satisfy the same resonated mode. It will make mode compete more acute and disadvantage to work of relativistic magnetron.
2002,
14.
Abstract:
In this paper, Vlasov antenna is studied systematically by the moment method (MM) and finite difference time domain (FDTD). Based on the simulation results, the process of mode conversion in the waveguide and radiation through the aperture is described in more details by clear physical pictures. The measurement results agree well with the numerical results. Furthermore, a new design of Vlasov-type antenna together with a radome, which will be used in a high power microwave system, is proposed. Compared with the traditional designs, the antenna gain has been increased by 6dB, and the first side lobe level has been decreased by 13dB.
In this paper, Vlasov antenna is studied systematically by the moment method (MM) and finite difference time domain (FDTD). Based on the simulation results, the process of mode conversion in the waveguide and radiation through the aperture is described in more details by clear physical pictures. The measurement results agree well with the numerical results. Furthermore, a new design of Vlasov-type antenna together with a radome, which will be used in a high power microwave system, is proposed. Compared with the traditional designs, the antenna gain has been increased by 6dB, and the first side lobe level has been decreased by 13dB.
2002,
14.
Abstract:
This article introduces the construction and working principle of angle tracking system of Surface-to-air Radar Jam System, mainly analyses six kinds of matters which effect the tracking accuracy and brings forward how to inprove the tracking accuracy in virtue of computer intelligent control.
This article introduces the construction and working principle of angle tracking system of Surface-to-air Radar Jam System, mainly analyses six kinds of matters which effect the tracking accuracy and brings forward how to inprove the tracking accuracy in virtue of computer intelligent control.
2002,
14.
Abstract:
The X-band transit time tube oscillator (TTTO) is a novel high power microwave device, simulation shows that it frequency-spectrum characteristic is related with its output, so the frequency spectrum diagnosis is an important work for the X-band TTTO research. Using t he frequency synthesis method, the frequency-spectrum characteristic of the X band TTTO is got with the system. Based on the frequency-spectrum characteristic, the structural parameters and working parameters of the X-band TTTO are adjusted to get better output.
The X-band transit time tube oscillator (TTTO) is a novel high power microwave device, simulation shows that it frequency-spectrum characteristic is related with its output, so the frequency spectrum diagnosis is an important work for the X-band TTTO research. Using t he frequency synthesis method, the frequency-spectrum characteristic of the X band TTTO is got with the system. Based on the frequency-spectrum characteristic, the structural parameters and working parameters of the X-band TTTO are adjusted to get better output.
2002,
14.
Abstract:
A new type detector was presented in this paper, which was developed based on novel sensors and new measuring circuits to achieve good sensitivity and reliability for HPM power measurement. Com pared with the previously developed X-band HPM detector, the new X-band detect or is characterized by 10 times higher sensitivity and over 9V output signal voltage amplitude at HPM power of 60kW. An S-band HPM detector was developed successfully for the first time. Both detectors can be used for power measuring of HP M whose pulse duration ranges from 10ns to 500ns.
A new type detector was presented in this paper, which was developed based on novel sensors and new measuring circuits to achieve good sensitivity and reliability for HPM power measurement. Com pared with the previously developed X-band HPM detector, the new X-band detect or is characterized by 10 times higher sensitivity and over 9V output signal voltage amplitude at HPM power of 60kW. An S-band HPM detector was developed successfully for the first time. Both detectors can be used for power measuring of HP M whose pulse duration ranges from 10ns to 500ns.
2002,
14.
Abstract:
This paper discusses the basic principle of high-voltage pulse corona for desulfuration and its demand for the performance of pulse voltage generator with repeat frequeny. Based on the discuss ion of the influence on supply system by the reactor, designing rules were put forward. The paper also discusses critical problem in designing the repeat frequency generator, the designing method as well as the parameters of different pulse forming lines.
This paper discusses the basic principle of high-voltage pulse corona for desulfuration and its demand for the performance of pulse voltage generator with repeat frequeny. Based on the discuss ion of the influence on supply system by the reactor, designing rules were put forward. The paper also discusses critical problem in designing the repeat frequency generator, the designing method as well as the parameters of different pulse forming lines.
2002,
14.
Abstract:
The theoretical models and the structure designs of the high power diode are described in this paper. The insulator, the structure of cathode and anode, the guide magnetic-field are analyzed and calculated in detail. The space charge limited current model, based on guide magnetic-field and theory of relativity approximation, is used to simulate t he relativity electron-beam and study the influence of diode structure and guide magneticfield on the characteristic of foilless diode beam-current.
The theoretical models and the structure designs of the high power diode are described in this paper. The insulator, the structure of cathode and anode, the guide magnetic-field are analyzed and calculated in detail. The space charge limited current model, based on guide magnetic-field and theory of relativity approximation, is used to simulate t he relativity electron-beam and study the influence of diode structure and guide magneticfield on the characteristic of foilless diode beam-current.
2002,
14.
Abstract:
Reliability of the sealed vacuum device is very important, and the main reason that affects reliability is its vacuum. As the degree of vacuum cannot be measured directly, an indirectly method is adopted in this paper. In this paper, the principle in measuring the vacuum of sealed vacuum device with Penning discharge is analyzed, the Penning discharge model of sealed vacuum device is established, the experimental device is designed, and pressure-ion current chart is presented.
Reliability of the sealed vacuum device is very important, and the main reason that affects reliability is its vacuum. As the degree of vacuum cannot be measured directly, an indirectly method is adopted in this paper. In this paper, the principle in measuring the vacuum of sealed vacuum device with Penning discharge is analyzed, the Penning discharge model of sealed vacuum device is established, the experimental device is designed, and pressure-ion current chart is presented.
