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RSS2006 Vol. 18, No. 03
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2006,
18.
Abstract:
A TEA CO2 laser was employed to ablate spray droplets for laser propulsion. The momentum coupling coefficient was derived from the force sensor data. Experimental results indicate that the coupling coefficient is largely dependent on droplet Sauter mean diameter(SMD), velocity and their joint distribution and that as SMD and velocity decrease with a narrower range of speed distribution, the momentum coupling coefficient increases.
A TEA CO2 laser was employed to ablate spray droplets for laser propulsion. The momentum coupling coefficient was derived from the force sensor data. Experimental results indicate that the coupling coefficient is largely dependent on droplet Sauter mean diameter(SMD), velocity and their joint distribution and that as SMD and velocity decrease with a narrower range of speed distribution, the momentum coupling coefficient increases.
2006,
18.
Abstract:
The corner cube mirror cavity consists of a corner cube mirror as the totally reflecting mirror and a parallel flat partially reflecting mirror as the output mirror. This paper presents an experimental study of the anti-misalignment stability and the output characteristics of the corner cube cavity laser compared with the plano-concave cavity and the plane-parallel cavity lasers. When the corner cube mirror is deflected and the misalignment angle turns to 16 mrad, the single-pulse output energy of the corner cube cavity decreases 9.2%, and the near-field laser spot figures of the corner cube cavity laser have little change; When the concave mirror is deflected and the misalignment angle turns to 0.4 mrad, the single-pulse output energy of the plano-concave cavity laser decreases 9%, and th
The corner cube mirror cavity consists of a corner cube mirror as the totally reflecting mirror and a parallel flat partially reflecting mirror as the output mirror. This paper presents an experimental study of the anti-misalignment stability and the output characteristics of the corner cube cavity laser compared with the plano-concave cavity and the plane-parallel cavity lasers. When the corner cube mirror is deflected and the misalignment angle turns to 16 mrad, the single-pulse output energy of the corner cube cavity decreases 9.2%, and the near-field laser spot figures of the corner cube cavity laser have little change; When the concave mirror is deflected and the misalignment angle turns to 0.4 mrad, the single-pulse output energy of the plano-concave cavity laser decreases 9%, and th
2006,
18.
Abstract:
Based on weak turbulence theory, an average coupling efficiency model and a relative power fluctuations model are derived for coupling space light into single mode fiber in the presence of atmospheric turbulence. The effects of turbulence-induced wavefront distortion, scintillation, aperture averaging and residual tracking error of the angle-tracked coupling system are considered together. Using the Hufnagel-Valley 5/7 refractive-index structure model, average coupling efficiency and relative power fluctuations are investigated for both downlink and uplink. It is shown that for downlink, with the increase of receiver aperture, the relative power fluctuations first decrease due to the aperture averaging, and then increase due to the turbulence-induced wavefront distortion, and for uplink, t
Based on weak turbulence theory, an average coupling efficiency model and a relative power fluctuations model are derived for coupling space light into single mode fiber in the presence of atmospheric turbulence. The effects of turbulence-induced wavefront distortion, scintillation, aperture averaging and residual tracking error of the angle-tracked coupling system are considered together. Using the Hufnagel-Valley 5/7 refractive-index structure model, average coupling efficiency and relative power fluctuations are investigated for both downlink and uplink. It is shown that for downlink, with the increase of receiver aperture, the relative power fluctuations first decrease due to the aperture averaging, and then increase due to the turbulence-induced wavefront distortion, and for uplink, t
2006,
18.
Abstract:
Two automatic data-collecting systems were set up respectively in inland and along the coast for measuring the atmospheric turbulence. By long-time observation a great amount of data were obtained. The daily variations and probability of the inner and outer scale of turbulence were analyzed. The mean values of the turbulence inner scale are all more than 10 mm and those of outer-scale are about 2 m in inland and along the coast. The daily variations of the inner scale are complex relatively and those of the outer scale are similar to turbulence intensity in inland. There was no explicit relationship between turbulence scale and turbulence intensity along the coast. The scales and probability distributions of the atmospheric turbulence always vary with the time and space. It is necessary to
Two automatic data-collecting systems were set up respectively in inland and along the coast for measuring the atmospheric turbulence. By long-time observation a great amount of data were obtained. The daily variations and probability of the inner and outer scale of turbulence were analyzed. The mean values of the turbulence inner scale are all more than 10 mm and those of outer-scale are about 2 m in inland and along the coast. The daily variations of the inner scale are complex relatively and those of the outer scale are similar to turbulence intensity in inland. There was no explicit relationship between turbulence scale and turbulence intensity along the coast. The scales and probability distributions of the atmospheric turbulence always vary with the time and space. It is necessary to
2006,
18.
Abstract:
The temporal and spectral properties of Bessel-Gauss pulsed beams with constant diffraction length in a linear dispersive medium are studied. It is shown that by a suitable choice of the spatial parameter β, Bessel-Gauss pulsed beams propagate along the axis without noticeable pulse broadening. If the propagation distance is smaller than the diffraction-free range, temporal pulse forms and normalized power spectra remain unchanged as the diffraction angle increases. However, if the propagation distance is larger than the diffraction-free range, the pulse duration broadens, and the spectra change from blueshifts to redshifts with the increasing diffraction angle.
The temporal and spectral properties of Bessel-Gauss pulsed beams with constant diffraction length in a linear dispersive medium are studied. It is shown that by a suitable choice of the spatial parameter β, Bessel-Gauss pulsed beams propagate along the axis without noticeable pulse broadening. If the propagation distance is smaller than the diffraction-free range, temporal pulse forms and normalized power spectra remain unchanged as the diffraction angle increases. However, if the propagation distance is larger than the diffraction-free range, the pulse duration broadens, and the spectra change from blueshifts to redshifts with the increasing diffraction angle.
2006,
18.
Abstract:
The study of boundary layer inhomogeneous is of great importance in studying the characteristic of atmospheric turbulence and the applicability of the classic theory. In this paper, the development of atmosphere boundary layer is simulated in a laboratory simulation tank, and beam patterns of mixed layer are recorded. Using wavelet transform method to determine the scaling region of the power spectrum of log-intensity from beam patterns in horizontal and vertical directions, the scaling exponents can be fitted and compared with the classic value of 8/3. The result shows that the mixed layer is quite homogeneous in horizontal direction and a little inhomogeneous in vertical direction.
The study of boundary layer inhomogeneous is of great importance in studying the characteristic of atmospheric turbulence and the applicability of the classic theory. In this paper, the development of atmosphere boundary layer is simulated in a laboratory simulation tank, and beam patterns of mixed layer are recorded. Using wavelet transform method to determine the scaling region of the power spectrum of log-intensity from beam patterns in horizontal and vertical directions, the scaling exponents can be fitted and compared with the classic value of 8/3. The result shows that the mixed layer is quite homogeneous in horizontal direction and a little inhomogeneous in vertical direction.
2006,
18.
Abstract:
The interactions between Gaussian-shaped solitons in the logarithmic saturable nonlinear media were numerically investigated. The results show that the interactions between Gaussian-shaped solitons are sensitive to relative amplitude and relative phase. In different regions of relative amplitude, the main effect is repulsion or attraction alternately, and due to the instability of Gaussian solitons, the beams breathe periodically after interactions. Along with the rising of the relative phase, there are stronger repulsions between the beams, until at the end of each cycle. The beams breathe also in this situation, and the larger angle they separate, the more strongly they breathe.
The interactions between Gaussian-shaped solitons in the logarithmic saturable nonlinear media were numerically investigated. The results show that the interactions between Gaussian-shaped solitons are sensitive to relative amplitude and relative phase. In different regions of relative amplitude, the main effect is repulsion or attraction alternately, and due to the instability of Gaussian solitons, the beams breathe periodically after interactions. Along with the rising of the relative phase, there are stronger repulsions between the beams, until at the end of each cycle. The beams breathe also in this situation, and the larger angle they separate, the more strongly they breathe.
2006,
18.
Abstract:
In this paper, by means of boundary finite-element method, the field distributions and eigenvalues of the fundamental mode of the plano-concave resonator with a tilted even-reflectivity plane mirror or a tilted Gaussian-reflectivity plane mirror are calculated and discussed. The results show that when the plane mirror tilts, the center of the mode distribution on it will move towards its edge along the tilting direction. When the tilt angle of the mirror is big enough, the mode will be distorted, the symmetry Gaussian distribution will disappear. Furthermore, with the increasing of the tilt angle the far field distributions become bad, and the eigenvalues decrease. Under the same conditions, the mode distortions induced by the tilted mirror are smaller for the plano-concave resonator with
In this paper, by means of boundary finite-element method, the field distributions and eigenvalues of the fundamental mode of the plano-concave resonator with a tilted even-reflectivity plane mirror or a tilted Gaussian-reflectivity plane mirror are calculated and discussed. The results show that when the plane mirror tilts, the center of the mode distribution on it will move towards its edge along the tilting direction. When the tilt angle of the mirror is big enough, the mode will be distorted, the symmetry Gaussian distribution will disappear. Furthermore, with the increasing of the tilt angle the far field distributions become bad, and the eigenvalues decrease. Under the same conditions, the mode distortions induced by the tilted mirror are smaller for the plano-concave resonator with
2006,
18.
Abstract:
In order to investigate the tribological performance of laser remelting layers, laser remelting processes were carried out on grey cast iron matrix. The microstructures consist typical γ austenite dendrite distributed on the eutectic substrate and the microhardness varies from HV0.2 800 to HV0.2 1 200. The optimal SRV tests were carried out using laser remelting layers as upper samples and grey cast irons as low samples. The morphologies of worn scars were observed with scanning electron microscopy (SEM). The SRV tests show that the laser remelting processes reduce the wear losses of wear couple and lower the friction coefficient (0.072 8～0.082 2). The wear mechanism is abrasive wear.
In order to investigate the tribological performance of laser remelting layers, laser remelting processes were carried out on grey cast iron matrix. The microstructures consist typical γ austenite dendrite distributed on the eutectic substrate and the microhardness varies from HV0.2 800 to HV0.2 1 200. The optimal SRV tests were carried out using laser remelting layers as upper samples and grey cast irons as low samples. The morphologies of worn scars were observed with scanning electron microscopy (SEM). The SRV tests show that the laser remelting processes reduce the wear losses of wear couple and lower the friction coefficient (0.072 8～0.082 2). The wear mechanism is abrasive wear.
2006,
18.
Abstract:
Using a 20 W fiber coupled LD as the pump source, the experiment of the gain-swithed Nd3+:YVO4 microchip laser was presented. 1 Hz～25 kHz repetition rate controllable Q switched laser with several W was obtained. The gain-switching from rate equation was theoretically investigated, and through the numerical solution the laser characteristics are analyzed. When the pump current is higher than the current which generates the single pulse, increasing the pump current or increasing the width of the pump current will generate several sub-pulses in one pump pulse. The wider the pump pulse is, the more output sub-pulses will be included in pump pulse. Increasing the repetition rate, the output laser has the same repetition rate as the pump laser, but more sub-pulses will be output in one pump pu
Using a 20 W fiber coupled LD as the pump source, the experiment of the gain-swithed Nd3+:YVO4 microchip laser was presented. 1 Hz～25 kHz repetition rate controllable Q switched laser with several W was obtained. The gain-switching from rate equation was theoretically investigated, and through the numerical solution the laser characteristics are analyzed. When the pump current is higher than the current which generates the single pulse, increasing the pump current or increasing the width of the pump current will generate several sub-pulses in one pump pulse. The wider the pump pulse is, the more output sub-pulses will be included in pump pulse. Increasing the repetition rate, the output laser has the same repetition rate as the pump laser, but more sub-pulses will be output in one pump pu
2006,
18.
Abstract:
Electromagnetic field theory and electron motion conservation equations are used to derive numerical model of transverse space-charge flow and magnetically insulated critical condition in the four usual transmission lines: planes, cylinders, cones and discs. Through numerical simulation, the dependence of the transverse space-charge flow on the geometrical configurations parameters of the transmission lines is quantitatively obtained. The space-charge flow decreases as the geometrical factor increases for cylinders or as the geometrical factor and the angle between anode and cathode increase and the cathode polar angle decreases for cones. This work provides theoretical basis for engineering design.
Electromagnetic field theory and electron motion conservation equations are used to derive numerical model of transverse space-charge flow and magnetically insulated critical condition in the four usual transmission lines: planes, cylinders, cones and discs. Through numerical simulation, the dependence of the transverse space-charge flow on the geometrical configurations parameters of the transmission lines is quantitatively obtained. The space-charge flow decreases as the geometrical factor increases for cylinders or as the geometrical factor and the angle between anode and cathode increase and the cathode polar angle decreases for cones. This work provides theoretical basis for engineering design.
2006,
18.
Abstract:
To calibrate photoconductive detectors with the synchrotron soft X-ray source, a new method based on gated integration has been proposed. It will replace the high sensitive measurement system based on high performance oscilloscopes and improve the preamplifier, of which the band reaches 2.9 GHz. The sensitivity of the gated integrator is 2.8×10-18 C/bit . The sensitivity dynamic calibration of the diamond detector has been completed at the Beijing Synchrotron Radiation Facility (BSRF) using the new method. A better signal noise rate has been got on the C,Al,Ni,Fe thin filter. The results of the test show that the sample detector is more sensitive on long wave band (50～280 eV) and this method is feasible in principle.
To calibrate photoconductive detectors with the synchrotron soft X-ray source, a new method based on gated integration has been proposed. It will replace the high sensitive measurement system based on high performance oscilloscopes and improve the preamplifier, of which the band reaches 2.9 GHz. The sensitivity of the gated integrator is 2.8×10-18 C/bit . The sensitivity dynamic calibration of the diamond detector has been completed at the Beijing Synchrotron Radiation Facility (BSRF) using the new method. A better signal noise rate has been got on the C,Al,Ni,Fe thin filter. The results of the test show that the sample detector is more sensitive on long wave band (50～280 eV) and this method is feasible in principle.
2006,
18.
Abstract:
In the inertial confinement fusion (ICF) system, there exists a special requirement of waveform of the laser pulse(a shaping pulse with a width of ns). This paper proposes a coherent pulse stacking method which can make the output stacking pulse meet the requirement of the ICF. It theoretically and technologically investigates the multi-pulse interference in time domain, derives the range of time detention (about the width of the single Gaussian pulse) and the phase control accuracy of neighbor pulses to achieve the requirement of smoothing.
In the inertial confinement fusion (ICF) system, there exists a special requirement of waveform of the laser pulse(a shaping pulse with a width of ns). This paper proposes a coherent pulse stacking method which can make the output stacking pulse meet the requirement of the ICF. It theoretically and technologically investigates the multi-pulse interference in time domain, derives the range of time detention (about the width of the single Gaussian pulse) and the phase control accuracy of neighbor pulses to achieve the requirement of smoothing.
2006,
18.
Abstract:
In order to understand the good qualities of the laser driving scheme with grazing incidence against to the scheme with normal incidence, the schemes of Ni-like Ag driven by normal incident lasers with long wavelengths of 6 μm and 3 mm were studied. Results show that for X-ray laser of Ni-like Ag, adopting laser with 6 μm and 3 mm wavelength, the laser energy mainly deposites on gain region or nearby, the electronic temperature on gain region dramatically increases and the gain coefficients dramatically increase too. With 3 mm wavelength laser, using 5 J driven laser energy, an effective gain of 20.7 cm-1 and a deeply saturated gain with a gain length product being 41.4 can be obtained. Comparing to 1w laser driven, only 19% driven laser energy is needed, and the effective gain increases
In order to understand the good qualities of the laser driving scheme with grazing incidence against to the scheme with normal incidence, the schemes of Ni-like Ag driven by normal incident lasers with long wavelengths of 6 μm and 3 mm were studied. Results show that for X-ray laser of Ni-like Ag, adopting laser with 6 μm and 3 mm wavelength, the laser energy mainly deposites on gain region or nearby, the electronic temperature on gain region dramatically increases and the gain coefficients dramatically increase too. With 3 mm wavelength laser, using 5 J driven laser energy, an effective gain of 20.7 cm-1 and a deeply saturated gain with a gain length product being 41.4 can be obtained. Comparing to 1w laser driven, only 19% driven laser energy is needed, and the effective gain increases
2006,
18.
Abstract:
Based on the two-dimensional magnetohydrodynamic(MHD) theory, the magnetic field penetration process at the conduction stage of a high-density, coaxial plasma opening switch (POS) was numerically simulated, and the evolution of the magnetic field distribution with time was obtained. The influence of the energy transportation on the magnetic field penetration was studied. It is shown that the magnetic field penetrates into the plasmas rapidly, and the temperature in the shock region increases greatly. The non-uniform distribution of temperature resulted from the compression of the plasma and the Ohmic heating speeds up the magnetic field penetration significantly. The conduction-time of the POS is 0.87 μs by the model with the energy transportation, which is shorter than that of the isothe
Based on the two-dimensional magnetohydrodynamic(MHD) theory, the magnetic field penetration process at the conduction stage of a high-density, coaxial plasma opening switch (POS) was numerically simulated, and the evolution of the magnetic field distribution with time was obtained. The influence of the energy transportation on the magnetic field penetration was studied. It is shown that the magnetic field penetrates into the plasmas rapidly, and the temperature in the shock region increases greatly. The non-uniform distribution of temperature resulted from the compression of the plasma and the Ohmic heating speeds up the magnetic field penetration significantly. The conduction-time of the POS is 0.87 μs by the model with the energy transportation, which is shorter than that of the isothe
2006,
18.
Abstract:
For the demands of inertial confinement fusion experiments, DT fuel gas and some diagnostic gases such as Ar should be filled into hollow glass microsphere(HGM). However, Ar could not be filled into HGM by means of usual thermal diffusion due to its big atomic size. In this article, neutron radiation was used to create defects in HGM to let Ar enter HGM based on radiation enhancing diffusion. The experimental results show that Ar can be filled into HGM at 500 ℃ and room temperature when the neutron dosage is up to 1×1018 cm-2. The diffusion coefficient after irradiation enhances to Dcav≥3.6×10-13 cm2/s。
For the demands of inertial confinement fusion experiments, DT fuel gas and some diagnostic gases such as Ar should be filled into hollow glass microsphere(HGM). However, Ar could not be filled into HGM by means of usual thermal diffusion due to its big atomic size. In this article, neutron radiation was used to create defects in HGM to let Ar enter HGM based on radiation enhancing diffusion. The experimental results show that Ar can be filled into HGM at 500 ℃ and room temperature when the neutron dosage is up to 1×1018 cm-2. The diffusion coefficient after irradiation enhances to Dcav≥3.6×10-13 cm2/s。
2006,
18.
Abstract:
During the development of the additional beam system of “Shengguang-Ⅱ” facility, two vacuum cones and inner final optical systems would be fabricated on the ICF target chamber in order to offer Thompson probe and X-ray probe, which would influence the stability of the chamber. The FEM (Finite Element Model) analysis was used in design of the target chamber in order to optimize the mechanical design of the vacuum cone and the final optical system. From the measurement results by the displacement-sensor, the target position error being 2.110 μm caused by radial vibration of the addition beam final optical elements is obtained.
During the development of the additional beam system of “Shengguang-Ⅱ” facility, two vacuum cones and inner final optical systems would be fabricated on the ICF target chamber in order to offer Thompson probe and X-ray probe, which would influence the stability of the chamber. The FEM (Finite Element Model) analysis was used in design of the target chamber in order to optimize the mechanical design of the vacuum cone and the final optical system. From the measurement results by the displacement-sensor, the target position error being 2.110 μm caused by radial vibration of the addition beam final optical elements is obtained.
2006,
18.
Abstract:
The Fourier transform method has been used to analyze the influence of modal amplitude and phase fluctuations in a mode-locked laser on performance of its output pulse. The results show that the pulse shape and the bandwidth remain essentially constant when the modes have amplitude and phase fluctuations, but appear superimposed on a fluctuations background. The phase variations will cause the fluctuation of peak. The physical picture in this paper is concise and is helpful to get stable mode-locked laser output in experiments.
The Fourier transform method has been used to analyze the influence of modal amplitude and phase fluctuations in a mode-locked laser on performance of its output pulse. The results show that the pulse shape and the bandwidth remain essentially constant when the modes have amplitude and phase fluctuations, but appear superimposed on a fluctuations background. The phase variations will cause the fluctuation of peak. The physical picture in this paper is concise and is helpful to get stable mode-locked laser output in experiments.
2006,
18.
Abstract:
Metal films with material theoretical density are important to measurement of equation of state under high pressure. In this paper, an aluminum film and a copper film used in EOS(equation of state) experiment are produced by diamond turning technology. Process parameters of finish machining are given, including the feed rate 0.001 mm/r, the spindle rotate speed 3 000 r/min, and the depth of cutting 1 μm. Then the surface roughness is characterized by a Form Talysurf series 2 device. The results indicate that the thickness of both aluminum film and copper film are less than 10 μm, the surface root mean square roughness less than 5 nm, the primary maximum peak to valley height less than 50 nm and the thickness uniformity more than 99%.
Metal films with material theoretical density are important to measurement of equation of state under high pressure. In this paper, an aluminum film and a copper film used in EOS(equation of state) experiment are produced by diamond turning technology. Process parameters of finish machining are given, including the feed rate 0.001 mm/r, the spindle rotate speed 3 000 r/min, and the depth of cutting 1 μm. Then the surface roughness is characterized by a Form Talysurf series 2 device. The results indicate that the thickness of both aluminum film and copper film are less than 10 μm, the surface root mean square roughness less than 5 nm, the primary maximum peak to valley height less than 50 nm and the thickness uniformity more than 99%.
2006,
18.
Abstract:
An X-band magnetically insulated transmission line oscillator (MILO) is configured and investigated numerically with KARAT code. The design thought is introduced, and the typical simulation results are illustrated and analyzed. In simulation, when the voltage is 520 kV, and the current is 64 kA, the high-power microwave (HPM) of TEM mode is generated with a power of 2.18 GW, a frequency of 9.3 GHz, and a power conversion efficiency of 6.5%.
An X-band magnetically insulated transmission line oscillator (MILO) is configured and investigated numerically with KARAT code. The design thought is introduced, and the typical simulation results are illustrated and analyzed. In simulation, when the voltage is 520 kV, and the current is 64 kA, the high-power microwave (HPM) of TEM mode is generated with a power of 2.18 GW, a frequency of 9.3 GHz, and a power conversion efficiency of 6.5%.
2006,
18.
Abstract:
This paper presents the simulation of the radiation from both the pure mode of TE11 and the mixed modes of TE11 and TM01 with different power proportion for circular wave-guides of different diameters. The directivities of E plane and of H plane are calculated, with the hypothesis of axially symmetric radiation patterns, which is usually used in the power measurement of HPM in far-field zones. The calculated directivities are compared with the simulated ones of the real radiation patterns. The results show that in the case of the pure mode and of the mixed modes with TM01 power proportion of 5% and 10%, the maximum difference between the calculated directivities and the simulated ones is less than 0.8 dB at H plane, while the minimum difference between the two kinds of directivities is lar
This paper presents the simulation of the radiation from both the pure mode of TE11 and the mixed modes of TE11 and TM01 with different power proportion for circular wave-guides of different diameters. The directivities of E plane and of H plane are calculated, with the hypothesis of axially symmetric radiation patterns, which is usually used in the power measurement of HPM in far-field zones. The calculated directivities are compared with the simulated ones of the real radiation patterns. The results show that in the case of the pure mode and of the mixed modes with TM01 power proportion of 5% and 10%, the maximum difference between the calculated directivities and the simulated ones is less than 0.8 dB at H plane, while the minimum difference between the two kinds of directivities is lar
2006,
18.
Abstract:
A generalized perfectly matched layer(GPML) in lossless and lossy media is proposed. The GPML is derived from the Maxwell’s equations in stretched coordinates and can be easily used in multiresolution time domain(MRTD). The validation of GPML is analyzed in frequency domain and the reflectances are attained in several conditions. An example is given to test the performance of GPML. The results show that the reflectance of GPML is below -40 dB under certain frequency and becomes smaller when the space step is smaller and GPML is thicker. GPML provides a general absorbing boundary condition for lossless and lossy media using MRTD.
A generalized perfectly matched layer(GPML) in lossless and lossy media is proposed. The GPML is derived from the Maxwell’s equations in stretched coordinates and can be easily used in multiresolution time domain(MRTD). The validation of GPML is analyzed in frequency domain and the reflectances are attained in several conditions. An example is given to test the performance of GPML. The results show that the reflectance of GPML is below -40 dB under certain frequency and becomes smaller when the space step is smaller and GPML is thicker. GPML provides a general absorbing boundary condition for lossless and lossy media using MRTD.
2006,
18.
Abstract:
A method to precisely measure the voltage standing wave ratio(VSWR) of a component with nonstandard interfaces, named directional coupler method, is put forward in the paper. The measurement principle of the method is presented, and the errors by the method are analyzed. The errors relate to the directivity of the coupler and the VSWR of the component.The method is used to measure a matching load with nonstandard interfaces. The experimental results(VSWR value is less than 1.2) are achieved. The results prove that the method is feasible. The method has eased the problems of measuring the VSWR of a component with nonstandard interfaces, which is commonly involved in the researches of high power microwave.
A method to precisely measure the voltage standing wave ratio(VSWR) of a component with nonstandard interfaces, named directional coupler method, is put forward in the paper. The measurement principle of the method is presented, and the errors by the method are analyzed. The errors relate to the directivity of the coupler and the VSWR of the component.The method is used to measure a matching load with nonstandard interfaces. The experimental results(VSWR value is less than 1.2) are achieved. The results prove that the method is feasible. The method has eased the problems of measuring the VSWR of a component with nonstandard interfaces, which is commonly involved in the researches of high power microwave.
2006,
18.
Abstract:
Some interesting characteristics of the solid-state semiconductor switch, the reverse switching dynistor(RSD), such as the time of voltage fall, current carrying capability and current rise rate, were investigated under the condition of being the closing switch of capacitive energy storage. A 25 ns voltage-falling time was achieved. When the voltage of main capacitor was 8 kV, the peak value of current pulse was 10.1 kA, pulse width and current rise rate were 34 μs and 2.03 kA/μs respectively. After adjusting parameters of the main discharge circuit, a current pulse was obtained at peak current of 8.5 kA with current rise rate of 7.2 kA/μs only when the main capacitor voltage was 3 kV. Experimental results show that RSD is a new type of high power semiconductor switch with fast turn-on,
Some interesting characteristics of the solid-state semiconductor switch, the reverse switching dynistor(RSD), such as the time of voltage fall, current carrying capability and current rise rate, were investigated under the condition of being the closing switch of capacitive energy storage. A 25 ns voltage-falling time was achieved. When the voltage of main capacitor was 8 kV, the peak value of current pulse was 10.1 kA, pulse width and current rise rate were 34 μs and 2.03 kA/μs respectively. After adjusting parameters of the main discharge circuit, a current pulse was obtained at peak current of 8.5 kA with current rise rate of 7.2 kA/μs only when the main capacitor voltage was 3 kV. Experimental results show that RSD is a new type of high power semiconductor switch with fast turn-on,
2006,
18.
Abstract:
The theory and characteristic of a compact Tesla transformer are introduced, and an unitized configuration design is performed for 1.0 MV, 100 Hz Tesla transformer and 40 W, 40 ns pulse forming line (PFL). Two coaxial open cores in Tesla transformer serve as the inner and outer conductors of PFL, and a traditional PFL is combined with the Tesla transformer, then the pulse generator can be smaller, more efficient, and more stable. The designed compact Tesla transformer employed in electron beams accelerator CHP01 can charge PFL of 600 pF for 1.3 MV voltage at a single shot, and keep 1.15 MV at 100 Hz repeated rates. Furthermore, a continuance run in 5 seconds is achieved by Tesla transformer under voltage and frequency ratings.
The theory and characteristic of a compact Tesla transformer are introduced, and an unitized configuration design is performed for 1.0 MV, 100 Hz Tesla transformer and 40 W, 40 ns pulse forming line (PFL). Two coaxial open cores in Tesla transformer serve as the inner and outer conductors of PFL, and a traditional PFL is combined with the Tesla transformer, then the pulse generator can be smaller, more efficient, and more stable. The designed compact Tesla transformer employed in electron beams accelerator CHP01 can charge PFL of 600 pF for 1.3 MV voltage at a single shot, and keep 1.15 MV at 100 Hz repeated rates. Furthermore, a continuance run in 5 seconds is achieved by Tesla transformer under voltage and frequency ratings.
2006,
18.
Abstract:
The lifetime of electron beam is an important parameter, which is directly relative to the operation of HLS. In this paper, the influence of the RF cavity voltage, the coupling factor, and the bunch length on the HLS electron lifetime is studied. It shows that the electron beam vacuum lifetime is comparable to the Touscheck lifetime in HLS. With the Beam Loss Monitor system, the relative change of the beam lifetime is measured, due to the change of the Touscheck lifetime. To increase the coupling factor, the vertical emmitance of beam is increased, and the beam lifetime is improved effectively. The operation of HLS is ensured.
The lifetime of electron beam is an important parameter, which is directly relative to the operation of HLS. In this paper, the influence of the RF cavity voltage, the coupling factor, and the bunch length on the HLS electron lifetime is studied. It shows that the electron beam vacuum lifetime is comparable to the Touscheck lifetime in HLS. With the Beam Loss Monitor system, the relative change of the beam lifetime is measured, due to the change of the Touscheck lifetime. To increase the coupling factor, the vertical emmitance of beam is increased, and the beam lifetime is improved effectively. The operation of HLS is ensured.
2006,
18.
Abstract:
A 22 stage 5 MV laser-triggered multi-stage switch was designed based on the principle of laser-produced plasma and over-voltage wave. A metal ring was connected to a voltage divider to form a voltage-holding ring which was used to solve the problem of field regularity in small space. The relative difference of the electronic field of the selfbreakdown gaps was less than 0.056 and the relative error of the electronic field of the laser-triggered gap was less than 0.080 in the voltage-holding ring scheme. The switch and switch container were designed based on the results of electrostatic calculation. The satety factor of the switch and its' container was 0.8. The breakdown electronic field was calculated by J.C.Martin formula.
A 22 stage 5 MV laser-triggered multi-stage switch was designed based on the principle of laser-produced plasma and over-voltage wave. A metal ring was connected to a voltage divider to form a voltage-holding ring which was used to solve the problem of field regularity in small space. The relative difference of the electronic field of the selfbreakdown gaps was less than 0.056 and the relative error of the electronic field of the laser-triggered gap was less than 0.080 in the voltage-holding ring scheme. The switch and switch container were designed based on the results of electrostatic calculation. The satety factor of the switch and its' container was 0.8. The breakdown electronic field was calculated by J.C.Martin formula.
2006,
18.
Abstract:
1D magnetohydrodynamics (MHD) model is used to describe the explosion of electric explosive wires. Using numerical method, the results about electric current of circuit, the voltage of electric explosive wires vs time, and the density, current density vs r are given. The relation between the length of explosive wires, the voltage of caption and the electric current, the voltage of electric explosive wires are discussed.
1D magnetohydrodynamics (MHD) model is used to describe the explosion of electric explosive wires. Using numerical method, the results about electric current of circuit, the voltage of electric explosive wires vs time, and the density, current density vs r are given. The relation between the length of explosive wires, the voltage of caption and the electric current, the voltage of electric explosive wires are discussed.
2006,
18.
Abstract:
The photocathode RF gun requests accurate synchronization between laser pulse and RF phase in Thomson scattering X-ray source facility. Based on theoretical analysis on mode-locked laser phase noise, methods of phase error detection and feedback control technique are discussed. An experimental system has been established including phase jitter measurement and PLL feedback control, which changes laser optical length using a PZT. The RMS laser phase jitter has reached 3.42 ps at open loop, and 1.46 ps at close loop.
The photocathode RF gun requests accurate synchronization between laser pulse and RF phase in Thomson scattering X-ray source facility. Based on theoretical analysis on mode-locked laser phase noise, methods of phase error detection and feedback control technique are discussed. An experimental system has been established including phase jitter measurement and PLL feedback control, which changes laser optical length using a PZT. The RMS laser phase jitter has reached 3.42 ps at open loop, and 1.46 ps at close loop.
2006,
18.
Abstract:
Radiochromic films containing a multi-arylamino methane compound were prepared, and their color changed from clear to green after irradiation under ultraviolet (UV) light. As the absorption spectrums show, the main absorption peak in the visual region locates around 626 nm, and there is a linear relationship between the response of optical density and radiation time. The response increases with UV light energy density enhancing. The response to fractioned irradiation is a little stronger than that to continuous irradiation. The response keeps constant at temperature of 20～50 ℃ and relative humidity 40%～60%. The sensitivity of the response is remarkably improved when halides are added into the radiochromic system. As the result of post-radiation effect, noteworthily, the response increas
Radiochromic films containing a multi-arylamino methane compound were prepared, and their color changed from clear to green after irradiation under ultraviolet (UV) light. As the absorption spectrums show, the main absorption peak in the visual region locates around 626 nm, and there is a linear relationship between the response of optical density and radiation time. The response increases with UV light energy density enhancing. The response to fractioned irradiation is a little stronger than that to continuous irradiation. The response keeps constant at temperature of 20～50 ℃ and relative humidity 40%～60%. The sensitivity of the response is remarkably improved when halides are added into the radiochromic system. As the result of post-radiation effect, noteworthily, the response increas
2006,
18.
Abstract:
According to proton radiography concepts of the Los Alamos National Laboratory, the expressions of areal density in high-energy proton radiography are obtained by studying the high-energy protons interactions with materials. The areal density uncertainty and the position resolution are analyzed. Compared with high-energy X-ray radiography, the detection of edges and density reconstruction for a thick object are more accurate as the transmitted flux of protons is increased. The effects of the multiple coulomb scattering and chromatic aberrations in the magnetic lenses on the spatial resolution are studied. It is shown that high-energy proton radiography is superior to high-energy X-ray radiography in penetrating power, areal density measurement, material composition identification and posit
According to proton radiography concepts of the Los Alamos National Laboratory, the expressions of areal density in high-energy proton radiography are obtained by studying the high-energy protons interactions with materials. The areal density uncertainty and the position resolution are analyzed. Compared with high-energy X-ray radiography, the detection of edges and density reconstruction for a thick object are more accurate as the transmitted flux of protons is increased. The effects of the multiple coulomb scattering and chromatic aberrations in the magnetic lenses on the spatial resolution are studied. It is shown that high-energy proton radiography is superior to high-energy X-ray radiography in penetrating power, areal density measurement, material composition identification and posit
2006,
18.
Abstract:
Using time-of-flight mass spectrometry, the multiple ionization process of seeded molecular cluster beams was studied by 532 nm nanosecond laser with intensity from 1010 to 1011 W·cm-2. Ions of Cq+, Oq+ and Iq+ (q=2~4) with translational energy of hundreds of eV were observed when the densest portion of the pulsed molecular beams of benzene, furan, methanol and methyl iodide were irradiated by the nanosecond laser. A model of “multiphoton ionization ignition-inverse bremsstrahlung absorption heated-electron collision ionization” is proposed to explain the generation of those multiply charged ions under the low intensity laser pulse. The kinds of the multiply charged ions as well as the ratio of each ion to the overall ion products did not decrease apparently even if the laser intensity
Using time-of-flight mass spectrometry, the multiple ionization process of seeded molecular cluster beams was studied by 532 nm nanosecond laser with intensity from 1010 to 1011 W·cm-2. Ions of Cq+, Oq+ and Iq+ (q=2~4) with translational energy of hundreds of eV were observed when the densest portion of the pulsed molecular beams of benzene, furan, methanol and methyl iodide were irradiated by the nanosecond laser. A model of “multiphoton ionization ignition-inverse bremsstrahlung absorption heated-electron collision ionization” is proposed to explain the generation of those multiply charged ions under the low intensity laser pulse. The kinds of the multiply charged ions as well as the ratio of each ion to the overall ion products did not decrease apparently even if the laser intensity
2006,
18.
Abstract:
Total ionizing dose effects of Actel FPGA chip A1280XL are analyzed in detail with interrupting dynamic bias voltage and dynamic bias voltage conditions. Experimentation results indicate that bias conditions have a great effect on total ionizing dose effects of FPGA chip. The damage threshold value of FPGA chip is 12.16 Gy(Si) under the dynamic bias voltage condition. The damage threshold value of FPGA chip is 33.2 Gy(Si) under interrupting dynamic bias voltage condition. The chip radiation effects are analyzed for programmable chip inside structure. Available hardening techniques are introduced to improve device radiation hardened total ionizing dose ability, such as using redundance technique for failure check and isolation, selecting proper shield material for shielding the devices.
Total ionizing dose effects of Actel FPGA chip A1280XL are analyzed in detail with interrupting dynamic bias voltage and dynamic bias voltage conditions. Experimentation results indicate that bias conditions have a great effect on total ionizing dose effects of FPGA chip. The damage threshold value of FPGA chip is 12.16 Gy(Si) under the dynamic bias voltage condition. The damage threshold value of FPGA chip is 33.2 Gy(Si) under interrupting dynamic bias voltage condition. The chip radiation effects are analyzed for programmable chip inside structure. Available hardening techniques are introduced to improve device radiation hardened total ionizing dose ability, such as using redundance technique for failure check and isolation, selecting proper shield material for shielding the devices.
2006,
18.
Abstract:
In the present work, the effects of correlation are systematically studied for the 4d9-4d85p transition of Xe9+ ion by using the multi-configuration Dirac-Fock method, and the results of the transition energies and probabilities are presented. Comparison with some existing experiments and theoretical calculations is made. It is found that the correlation effects are very important in this case. According to the very good agreement between our calculations and experimental results and the agreement between transition probabilities in Babushkin gauge and Coulomb gauge, the present results are reasonable.
In the present work, the effects of correlation are systematically studied for the 4d9-4d85p transition of Xe9+ ion by using the multi-configuration Dirac-Fock method, and the results of the transition energies and probabilities are presented. Comparison with some existing experiments and theoretical calculations is made. It is found that the correlation effects are very important in this case. According to the very good agreement between our calculations and experimental results and the agreement between transition probabilities in Babushkin gauge and Coulomb gauge, the present results are reasonable.
2006,
18.
Abstract:
A 4 MV water pulse forming line switch that would be used in a water pulse forming line machine was designed based on the experiments of the 1 MV water self-breaking switch. The designed breakdown voltage is 4 MV with a current about 600 kA. The water self-breaking switch is made up of electrodes, a prepulse suppression plane and joint parts. The water switch is at the joint of pulse forming line and water insulated tri-plate transmission line. The gaps of the switch are arrayed at the input section of the tri-plate transmission line linearly. The discharge current of each gap will be tested by Rogowski coil while the input and output voltages of the switch by D-dot probes. Present 2 D and 3 D models of the electrostatic field analysis are useful tools for the design. There are many differ
A 4 MV water pulse forming line switch that would be used in a water pulse forming line machine was designed based on the experiments of the 1 MV water self-breaking switch. The designed breakdown voltage is 4 MV with a current about 600 kA. The water self-breaking switch is made up of electrodes, a prepulse suppression plane and joint parts. The water switch is at the joint of pulse forming line and water insulated tri-plate transmission line. The gaps of the switch are arrayed at the input section of the tri-plate transmission line linearly. The discharge current of each gap will be tested by Rogowski coil while the input and output voltages of the switch by D-dot probes. Present 2 D and 3 D models of the electrostatic field analysis are useful tools for the design. There are many differ
2006,
18.
Abstract:
Based on ceramic pulse capacitors and high press gas switch, a 60 kV coaxial fast rising pulse source was developed. A foil capacitive divider and a resistive divider were developed for measuring the output voltage of the fast rising pulse source. The test result indicats that the rising time of the output voltage of the pulse source is less than 2.3 ns and the pulse width is about 28 ns with a 50 W dummy load. This result agrees with the newest EMP standard of IEC.
Based on ceramic pulse capacitors and high press gas switch, a 60 kV coaxial fast rising pulse source was developed. A foil capacitive divider and a resistive divider were developed for measuring the output voltage of the fast rising pulse source. The test result indicats that the rising time of the output voltage of the pulse source is less than 2.3 ns and the pulse width is about 28 ns with a 50 W dummy load. This result agrees with the newest EMP standard of IEC.
2006,
18.
Abstract:
A new kind of epoxy compsite for vacuum insulator of the pulsed power devices is developed. The preparation process and the test result of the composite sample are presented in this paper. Some samples with different weight percentage are developed for the test. From the result, we can get that loading a quantity of hydrated alumina powder into the epoxy can decrease the surface resistivity from 5×1016 Ω to 6×1011 Ω. And using this method favors releasing the residual charge that deposited in the insulator surface during flashover. As a result, the flashover voltage of the epoxy composite is increased from 17 kV to 28 kV at same experiment condition.
A new kind of epoxy compsite for vacuum insulator of the pulsed power devices is developed. The preparation process and the test result of the composite sample are presented in this paper. Some samples with different weight percentage are developed for the test. From the result, we can get that loading a quantity of hydrated alumina powder into the epoxy can decrease the surface resistivity from 5×1016 Ω to 6×1011 Ω. And using this method favors releasing the residual charge that deposited in the insulator surface during flashover. As a result, the flashover voltage of the epoxy composite is increased from 17 kV to 28 kV at same experiment condition.
2006,
18.
Abstract:
In Z-pinch experiment, the one-dimensional temporal-spatial distribution of X-ray power is recorded by photographic films with nonlinear luminosity response. After processing by using a simulative characteristic function, the X-ray images are spatially integrated and then compared with X-ray waveforms obtained with X-ray Power Meter. The results show that the two kinds of waveforms are well coincident, which validates the capacity of the simulative characteristic function.
In Z-pinch experiment, the one-dimensional temporal-spatial distribution of X-ray power is recorded by photographic films with nonlinear luminosity response. After processing by using a simulative characteristic function, the X-ray images are spatially integrated and then compared with X-ray waveforms obtained with X-ray Power Meter. The results show that the two kinds of waveforms are well coincident, which validates the capacity of the simulative characteristic function.
2006,
18.
Abstract:
It is required that the peak current of high power pulsed driver for fast Z-pinch reaches 60 MA to realize inertial confine fusion（ICF）and high yield (HY). With the conventional technological methods similar to the Z or Saturn apparatus, increasing driver current further is impractical and difficult according to the cost, structure complexity and reliability of the driver, so it is necessary to develop novel fast pulsed high current driver. The present art-of-state and trends of fast Z-pinch driver are summarized in the paper, and the typical conceptual designs and technological methods on ICF/HY PRS (plasma radiation source) and destroying-level super X-ray simulators in USA and Russia are outlined, such as HCEI’s UGXX1 driver and new Saturn driver based on fast linear transformer driv
It is required that the peak current of high power pulsed driver for fast Z-pinch reaches 60 MA to realize inertial confine fusion（ICF）and high yield (HY). With the conventional technological methods similar to the Z or Saturn apparatus, increasing driver current further is impractical and difficult according to the cost, structure complexity and reliability of the driver, so it is necessary to develop novel fast pulsed high current driver. The present art-of-state and trends of fast Z-pinch driver are summarized in the paper, and the typical conceptual designs and technological methods on ICF/HY PRS (plasma radiation source) and destroying-level super X-ray simulators in USA and Russia are outlined, such as HCEI’s UGXX1 driver and new Saturn driver based on fast linear transformer driv
2006,
18.
Abstract:
An electrolysis corrosion method was used in producing ultra-fine tungsten wires with diameters less than 7 μm. The main factors that influence the tangsten wire were investigated, including the temperatures, KOH mass fraction of the electrolytic solution, electrolytic potentials and coiling velocity on the tungsten wires. The results show that the electrolytic potential and coiling velocity are the most important factors. The morphologies, roughness and strengths of the as-produced ultra-fine wires were characterized by Scanning Electronic Microscopy (SEM), Atomic Force Microscopy (AFM) and Tension/Compression Tester. Compared with the initial wires, the as-fabricated ultra-fine tungsten wires, 3.5 μm in diameter, with a surface extraction roughness of 2.42 nm and a tensile strength of
An electrolysis corrosion method was used in producing ultra-fine tungsten wires with diameters less than 7 μm. The main factors that influence the tangsten wire were investigated, including the temperatures, KOH mass fraction of the electrolytic solution, electrolytic potentials and coiling velocity on the tungsten wires. The results show that the electrolytic potential and coiling velocity are the most important factors. The morphologies, roughness and strengths of the as-produced ultra-fine wires were characterized by Scanning Electronic Microscopy (SEM), Atomic Force Microscopy (AFM) and Tension/Compression Tester. Compared with the initial wires, the as-fabricated ultra-fine tungsten wires, 3.5 μm in diameter, with a surface extraction roughness of 2.42 nm and a tensile strength of
