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RSS2006 Vol. 18, No. 08
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2006,
18.
Abstract:
Based on dielectric physic-optics , the method for analysis of high power microwave vacuum output window is discussed, by which an X band ,1.5 GW pulse power handling ability disk type Teflon vacuum output window is analyzed. The test results are in good agreement with the prediction. The method can be used for designing microwave lens and radomes.
Based on dielectric physic-optics , the method for analysis of high power microwave vacuum output window is discussed, by which an X band ,1.5 GW pulse power handling ability disk type Teflon vacuum output window is analyzed. The test results are in good agreement with the prediction. The method can be used for designing microwave lens and radomes.
2006,
18.
Abstract:
In this paper, the Gedney-perfectly matched layer(PML) absorbing boundary condition for the finite-difference time-domain(FDTD) method is implemented and validated. And also,the Gedney-PML parameters are optimized. The results show that the numerical reflection is lower than other absorbing boundaries. The optimization of the thickness of the medium and the conductance distributing factor are in agreement with Gedney’s empirical values. The module of this PML is added into the homemade software CHIPIC and enables the latter better wave absorbing than MAGIC. In addition, this module is proved applicable by simulating the model of magnetron in 2D polar coordinates system.
In this paper, the Gedney-perfectly matched layer(PML) absorbing boundary condition for the finite-difference time-domain(FDTD) method is implemented and validated. And also,the Gedney-PML parameters are optimized. The results show that the numerical reflection is lower than other absorbing boundaries. The optimization of the thickness of the medium and the conductance distributing factor are in agreement with Gedney’s empirical values. The module of this PML is added into the homemade software CHIPIC and enables the latter better wave absorbing than MAGIC. In addition, this module is proved applicable by simulating the model of magnetron in 2D polar coordinates system.
2006,
18.
Abstract:
Based on the difference between theoretical analysis and soft model, the effect of the ratio of the tape width to helix pitch on the surface current distribution of the tape helix was simulated using 3-D simulation software HFSS. It is found that the bigger the ratio is, the more asymmetric the surface current distribution is. While the phase shift of the Floquet boundary is 90°, the surface current distribution is the most asymmetric. Under different frequencies, the accuracy of the uniformity assumption of the surface surrent distribution is different.
Based on the difference between theoretical analysis and soft model, the effect of the ratio of the tape width to helix pitch on the surface current distribution of the tape helix was simulated using 3-D simulation software HFSS. It is found that the bigger the ratio is, the more asymmetric the surface current distribution is. While the phase shift of the Floquet boundary is 90°, the surface current distribution is the most asymmetric. Under different frequencies, the accuracy of the uniformity assumption of the surface surrent distribution is different.
2006,
18.
Abstract:
A high temperature open resonator measuring system for low loss radome materials is introduced. The scalar network analyzer measures the open resonator with sweeping frequency method under the control of a computer. After getting the resonance frequency and Q factor of the vacant and loaded cavity, the system works out the dielectric parameters and loss tangent of the material being tested. The dielectric is heated up by the temperature controller with a highest temperature more than 1 000 ℃. The test results of teflon by this system are close to the data in the literatures and the measurements of a kind of low loss radome material are also quite satisfactory.
A high temperature open resonator measuring system for low loss radome materials is introduced. The scalar network analyzer measures the open resonator with sweeping frequency method under the control of a computer. After getting the resonance frequency and Q factor of the vacant and loaded cavity, the system works out the dielectric parameters and loss tangent of the material being tested. The dielectric is heated up by the temperature controller with a highest temperature more than 1 000 ℃. The test results of teflon by this system are close to the data in the literatures and the measurements of a kind of low loss radome material are also quite satisfactory.
2006,
18.
Abstract:
The plasma tensor dielectric permittivity and electromagnetic wave accurate expressions in the arbitrary axial magnetic field are obtained from the Maxwell’s equations and the double component plasma particle linear movement equations. It is showed that E wave and H wave can’t be separated in this kind of plasma wave-guide. The axial-symmetrical solutions for the field components are obtained, which have the same form as that in ref.［4］ with the single-wave-approximation. The electromagnetic wave accurate expressions are very important for the research of the interaction between the plasma and the electromagnetic wave.
The plasma tensor dielectric permittivity and electromagnetic wave accurate expressions in the arbitrary axial magnetic field are obtained from the Maxwell’s equations and the double component plasma particle linear movement equations. It is showed that E wave and H wave can’t be separated in this kind of plasma wave-guide. The axial-symmetrical solutions for the field components are obtained, which have the same form as that in ref.［4］ with the single-wave-approximation. The electromagnetic wave accurate expressions are very important for the research of the interaction between the plasma and the electromagnetic wave.
2006,
18.
Abstract:
Five kinds of radio fuzes are irradiated by UWS-EMP, and coupling pattern and working mechanism between radio fuzes and the energy of UWS-EMP are analysed based on irradiation experiments. Analysis results show that the energy of UWS-EMP couples to fuzes via the power module of fuzes, causes silicon control rectifier conduction, and results in fusing. The radio fuzes are enhanced based on the coupling pattern and working mechanism. The improved fuzes are irradiated and simulated. The results indicate that the enhancement has greatly improved the ability of the radio fuzes against UWS-EMP. The enhancement doesn’t influence the efficiency of the fuzes.
Five kinds of radio fuzes are irradiated by UWS-EMP, and coupling pattern and working mechanism between radio fuzes and the energy of UWS-EMP are analysed based on irradiation experiments. Analysis results show that the energy of UWS-EMP couples to fuzes via the power module of fuzes, causes silicon control rectifier conduction, and results in fusing. The radio fuzes are enhanced based on the coupling pattern and working mechanism. The improved fuzes are irradiated and simulated. The results indicate that the enhancement has greatly improved the ability of the radio fuzes against UWS-EMP. The enhancement doesn’t influence the efficiency of the fuzes.
2006,
18.
Abstract:
An S-band 45 MW pulsed klystron is developed in Institute of High Energy Physics (IHEP).This klystron is a modified version of the existing 30 MW tube, which produces 45 MW at a 320 kV beam voltage by optimizing the focusing magnetic field. Therefore, the focusing coil needs to be re-arranged and its supporting structure is newly designed to meet 45 MW klystron demands. This paper describes the design, manufacture and operation of the focusing magnet system. The results of the magnetic field, the high power of the tube are presented. The operation status of the focusing magnet system is also included. The high power test results of the prototype tube show that the design, the manufacture and the operation of the focusing magnet system are successful.
An S-band 45 MW pulsed klystron is developed in Institute of High Energy Physics (IHEP).This klystron is a modified version of the existing 30 MW tube, which produces 45 MW at a 320 kV beam voltage by optimizing the focusing magnetic field. Therefore, the focusing coil needs to be re-arranged and its supporting structure is newly designed to meet 45 MW klystron demands. This paper describes the design, manufacture and operation of the focusing magnet system. The results of the magnetic field, the high power of the tube are presented. The operation status of the focusing magnet system is also included. The high power test results of the prototype tube show that the design, the manufacture and the operation of the focusing magnet system are successful.
2006,
18.
Abstract:
The transmitter beam is Gaussian for real satellite-ground laser communication system. The pointing jitter and atmospheric scintillation are the main noise sources for satellite-ground laser link. The channel model of satellite-ground laser communication link is presented in presence of the effects of atmospheric scintillation and pointing jitter on the quality of communication. The problem of the optimum ratio of beam divergence angle to pointing error is analyzed. The results indicate that there is an optimum ratio of beam divergence angle to pointing error that maximizes the link margin for different requirement of bit error rate for uplink, and there is an optimum ratio of beam divergence angle to pointing error that minimizes the required transmitter power to satisfy the bit error rat
The transmitter beam is Gaussian for real satellite-ground laser communication system. The pointing jitter and atmospheric scintillation are the main noise sources for satellite-ground laser link. The channel model of satellite-ground laser communication link is presented in presence of the effects of atmospheric scintillation and pointing jitter on the quality of communication. The problem of the optimum ratio of beam divergence angle to pointing error is analyzed. The results indicate that there is an optimum ratio of beam divergence angle to pointing error that maximizes the link margin for different requirement of bit error rate for uplink, and there is an optimum ratio of beam divergence angle to pointing error that minimizes the required transmitter power to satisfy the bit error rat
2006,
18.
Abstract:
For the degradation characteristic of capacitor bank used in high power laser energy module, a reliability assessment method based on compound Poisson process is proposed and the parameters of the model are obtained by moment estimation method. The reliability index, such as average degradation, reliability and average life are estimated by Bootstrap simulation method. A numerical example is given to illustrate the effectivity of the method. Compared with traditional reliability assessment method based on life data, the proposed one based on capacitor degradation information can give objective results with scarce life data or even zero failures.
For the degradation characteristic of capacitor bank used in high power laser energy module, a reliability assessment method based on compound Poisson process is proposed and the parameters of the model are obtained by moment estimation method. The reliability index, such as average degradation, reliability and average life are estimated by Bootstrap simulation method. A numerical example is given to illustrate the effectivity of the method. Compared with traditional reliability assessment method based on life data, the proposed one based on capacitor degradation information can give objective results with scarce life data or even zero failures.
2006,
18.
Abstract:
Based on the temporal covariance of logarithmic amplitude, analytical expression was obtained for aperture receiving power spectrum of atmospheric scintillation of satellite-to-ground downlink. The effect of the receiving aperture and outer scale of turbulence on the power spectrum of atmospheric scintillation was analyzed. The results indicate that the power spectrum of atmospheric scintillation includes low-frequency spectrum and high-frequency spectrum. The amplitude of low-frequency spectrum is constant. The high-frequency spectrum obeys the power law and the absolute value of power-law is 11/3. When the aperture scale increases, the power spectrum gradually increases its amplitude while keeping its shape. With the outer scale of turbulence increasing, the amplitude of low-frequency sp
Based on the temporal covariance of logarithmic amplitude, analytical expression was obtained for aperture receiving power spectrum of atmospheric scintillation of satellite-to-ground downlink. The effect of the receiving aperture and outer scale of turbulence on the power spectrum of atmospheric scintillation was analyzed. The results indicate that the power spectrum of atmospheric scintillation includes low-frequency spectrum and high-frequency spectrum. The amplitude of low-frequency spectrum is constant. The high-frequency spectrum obeys the power law and the absolute value of power-law is 11/3. When the aperture scale increases, the power spectrum gradually increases its amplitude while keeping its shape. With the outer scale of turbulence increasing, the amplitude of low-frequency sp
2006,
18.
Abstract:
Taking HF lasing as an example, line selecting performance of a single tube discharge driven subsonic CW HF/DF chemical laser was tested with grating dispersive cavity under the 1st order oscillating 1st coupling mode. The difference between the results of setting cavity axis at 2.0 mm and 0.5 mm downstream of hydrogen injecting orifice is dramatic. The results of the spectrum identification indicate that even for the subsonic chemical laser device, which owns only millimeter range flow direction's active length, line selected performance is greatly influenced by the cavity axis' relative position to the H2 injecting orifice. With the increase of this range, the transitions between the higher vibration states tend to be weaker, while the transitions between lower vibration-states more stro
Taking HF lasing as an example, line selecting performance of a single tube discharge driven subsonic CW HF/DF chemical laser was tested with grating dispersive cavity under the 1st order oscillating 1st coupling mode. The difference between the results of setting cavity axis at 2.0 mm and 0.5 mm downstream of hydrogen injecting orifice is dramatic. The results of the spectrum identification indicate that even for the subsonic chemical laser device, which owns only millimeter range flow direction's active length, line selected performance is greatly influenced by the cavity axis' relative position to the H2 injecting orifice. With the increase of this range, the transitions between the higher vibration states tend to be weaker, while the transitions between lower vibration-states more stro
2006,
18.
Abstract:
This paper reported a ZGP (zinc germanium phosphide) optical parametric oscillator (OPO) pumped by high-repetition rate 2 mm OPO. Type Ⅰ ZGP crystal (ZnGeP2) with the size of 5.5 mm×6 mm×18 mm was cut at phase matching angles of 55° and 0°. Under 4.0 kHz repetition rate, 310 mW mid-IR laser was obtained when the random polarization 2 mm pumping power was 5.2 W. The optical-to-optical efficiency of the p-polarized 2 mm to 3~5 mm was 12%. The experimental wavelength tuning curve of ZGP OPO was also achieved by tuning the angle of the ZGP crystal. It accorded with the theoretical rule in the error range.
This paper reported a ZGP (zinc germanium phosphide) optical parametric oscillator (OPO) pumped by high-repetition rate 2 mm OPO. Type Ⅰ ZGP crystal (ZnGeP2) with the size of 5.5 mm×6 mm×18 mm was cut at phase matching angles of 55° and 0°. Under 4.0 kHz repetition rate, 310 mW mid-IR laser was obtained when the random polarization 2 mm pumping power was 5.2 W. The optical-to-optical efficiency of the p-polarized 2 mm to 3~5 mm was 12%. The experimental wavelength tuning curve of ZGP OPO was also achieved by tuning the angle of the ZGP crystal. It accorded with the theoretical rule in the error range.
2006,
18.
Abstract:
The construction process and characteristics of the deformable mirror eigen mode are presented. The eigen modes of 37-channel micro-machined membrane deformable mirror from OKO Ltd are listed and fitted with the former 65 order Zernike polynomial. An experiment setup system is established based on micromachined membrane deformable mirror as wavefront corrector, Shack-Hartmann wavefront sensor as wavefront detector and the eigen modes as wavefront control algorithm. The experiment results demonstrate that the eigen modes can both act as basic function which provides the possibility of keeping some modes while compensating other modes and the control algorithm in the adaptive optics system especially in the case of micromachined membrane deformable mirror as wavefront corrector.
The construction process and characteristics of the deformable mirror eigen mode are presented. The eigen modes of 37-channel micro-machined membrane deformable mirror from OKO Ltd are listed and fitted with the former 65 order Zernike polynomial. An experiment setup system is established based on micromachined membrane deformable mirror as wavefront corrector, Shack-Hartmann wavefront sensor as wavefront detector and the eigen modes as wavefront control algorithm. The experiment results demonstrate that the eigen modes can both act as basic function which provides the possibility of keeping some modes while compensating other modes and the control algorithm in the adaptive optics system especially in the case of micromachined membrane deformable mirror as wavefront corrector.
2006,
18.
Abstract:
Based on the extended Huygens-Fresnel principle, the expression for the polarization state of partially coherent electromagnetic beams in turbulent atmosphere is derived. This paper deals with the influence of turbulence on the polarization of the Electromagnetic Gaussian Schell-model (EGSM) beam, which is taken as a typical example of partially coherent light. It is demonstrated that at the axial points, the higher the refractive index structure constant is, the more quickly the degree of polarization tends to the maximum value, and the smaller of the maximum polarization becomes. It is found that the larger the beam width is, the further the position of the degree of polarization takes its maximum. With the increment of the beam width, the maximum degree of polarization increases first,
Based on the extended Huygens-Fresnel principle, the expression for the polarization state of partially coherent electromagnetic beams in turbulent atmosphere is derived. This paper deals with the influence of turbulence on the polarization of the Electromagnetic Gaussian Schell-model (EGSM) beam, which is taken as a typical example of partially coherent light. It is demonstrated that at the axial points, the higher the refractive index structure constant is, the more quickly the degree of polarization tends to the maximum value, and the smaller of the maximum polarization becomes. It is found that the larger the beam width is, the further the position of the degree of polarization takes its maximum. With the increment of the beam width, the maximum degree of polarization increases first,
2006,
18.
Abstract:
The 3D elastic mechanics and finite-element structure analysis priniple were provided. The mechanics characteristics of the three-faced aluminous rotating mirror were analyzed, and the finite-element model was established. The stress distributions of the tri-face aluminous mirror were presented under three fits of the shaft and axle hole. The simulation results indicate that the fit modes affect the mirror structual strength little, but the axle hole weakens the structual strength obviously. The improved structure which diminishes the inner stress of the rotating mirror was presented, whose structual strength is 2.9 times and the utmost linear rate is 1.7 times of the old one, so it is more propitious to the frame-camera.
The 3D elastic mechanics and finite-element structure analysis priniple were provided. The mechanics characteristics of the three-faced aluminous rotating mirror were analyzed, and the finite-element model was established. The stress distributions of the tri-face aluminous mirror were presented under three fits of the shaft and axle hole. The simulation results indicate that the fit modes affect the mirror structual strength little, but the axle hole weakens the structual strength obviously. The improved structure which diminishes the inner stress of the rotating mirror was presented, whose structual strength is 2.9 times and the utmost linear rate is 1.7 times of the old one, so it is more propitious to the frame-camera.
2006,
18.
Abstract:
The propagation regularity of the laser in the 1D resonance media was studied by solving the Maxwell-Bloch equations with definite difference method. It was found that the 2p pulse would not propagate as a soliton but split if the dipole moment or the particles concentration of the resonance media was over a certain value. When two 2p pulses of different pulse widthes propagated through the resonance media, the shorter-duration pulse would catch up with the longer one. If the peak area signs of the two pulses were the same, the optical field indensity would not change obviously, it would add up and a powerful pulse with larger peak area but shorter duration would be generated. Therefore a powerful field could be generated on a fix position by adjusting the pulse width or time lapse of the
The propagation regularity of the laser in the 1D resonance media was studied by solving the Maxwell-Bloch equations with definite difference method. It was found that the 2p pulse would not propagate as a soliton but split if the dipole moment or the particles concentration of the resonance media was over a certain value. When two 2p pulses of different pulse widthes propagated through the resonance media, the shorter-duration pulse would catch up with the longer one. If the peak area signs of the two pulses were the same, the optical field indensity would not change obviously, it would add up and a powerful pulse with larger peak area but shorter duration would be generated. Therefore a powerful field could be generated on a fix position by adjusting the pulse width or time lapse of the
2006,
18.
Abstract:
Detecting and calculating accuracy of centroid of focal spot affects the detecting accuracy of Hartmann-Shack wavefront sensor. Noise will reduce the detecting accuracy when the whole sub-aperture is used as the detecting window. The influence of window selection on centroid detection error is great. In this paper, the method of optimizing detecting window based on traditional algorithm is proposed in order to improve the detection accuracy. Computer simulation indicates that the detection error can be decreased. Also, an optical system for distorted wavefront measurement is built with array Fresnel zone plates as the wavefront sensor. The experimental results show the accuracy of centroid detection is improved. The rms value of the error for reconstruction wavefront with high noise can be
Detecting and calculating accuracy of centroid of focal spot affects the detecting accuracy of Hartmann-Shack wavefront sensor. Noise will reduce the detecting accuracy when the whole sub-aperture is used as the detecting window. The influence of window selection on centroid detection error is great. In this paper, the method of optimizing detecting window based on traditional algorithm is proposed in order to improve the detection accuracy. Computer simulation indicates that the detection error can be decreased. Also, an optical system for distorted wavefront measurement is built with array Fresnel zone plates as the wavefront sensor. The experimental results show the accuracy of centroid detection is improved. The rms value of the error for reconstruction wavefront with high noise can be
2006,
18.
Abstract:
By using one type Ⅰ doubling and two type Ⅱ tripling KDP crystals in quadrature, the influence of the bandwidth of the fundamental field and the detuning angles of the mixers on the power spectrum of the third harmonic field has been discussed. The factors influencing the conversion efficiency of the third harmonic field has also been analyzed. It is shown that the distribution of the power spectrum of the third harmonic field depends on the bandwidth of the input fundamental field and the detuning angles of the mixing crystals. The bandwidth of the third harmonic field is nearly 3 times that of the input fundamental field. Furthermore, the non-uniformity of the temporal profile of the third harmonic field induced by the temporal modulation of the fundamental field can be improved and th
By using one type Ⅰ doubling and two type Ⅱ tripling KDP crystals in quadrature, the influence of the bandwidth of the fundamental field and the detuning angles of the mixers on the power spectrum of the third harmonic field has been discussed. The factors influencing the conversion efficiency of the third harmonic field has also been analyzed. It is shown that the distribution of the power spectrum of the third harmonic field depends on the bandwidth of the input fundamental field and the detuning angles of the mixing crystals. The bandwidth of the third harmonic field is nearly 3 times that of the input fundamental field. Furthermore, the non-uniformity of the temporal profile of the third harmonic field induced by the temporal modulation of the fundamental field can be improved and th
2006,
18.
Abstract:
The preparation of the special adhesive for hollow glass microsphere sealing in the inertial confinement fusion(ICF) experiment was introduced. The influences of the toughener and coupling agent on the morphology, thermal properties and shear strength of the adhesive were analyzed. The test results indicate that the thermal decomposition temperature of the epoxy silicone adhesive decreases with the increasing of the toughener content, the comprehensive property of the epoxy silicone adhesive is the best when the toughener content is 25%. The coupling agent can improve the bonding strength of the adhesive-metal interface and the mechanical property of the epoxy silicone adhesive. The micro-structure study shows that the micro-phase separation exists between the epoxy molecular chain and the
The preparation of the special adhesive for hollow glass microsphere sealing in the inertial confinement fusion(ICF) experiment was introduced. The influences of the toughener and coupling agent on the morphology, thermal properties and shear strength of the adhesive were analyzed. The test results indicate that the thermal decomposition temperature of the epoxy silicone adhesive decreases with the increasing of the toughener content, the comprehensive property of the epoxy silicone adhesive is the best when the toughener content is 25%. The coupling agent can improve the bonding strength of the adhesive-metal interface and the mechanical property of the epoxy silicone adhesive. The micro-structure study shows that the micro-phase separation exists between the epoxy molecular chain and the
2006,
18.
Abstract:
For the laser plasma diagnostic system in the inertial confinement fusion(ICF) drivers, the logarithmic axicon was adopted and improved by fifth-order super-Guassian edge smoothing, centre apodization and choosing suitable device parameters. The simulation experiments indicated that, to obtain a long-focal depth, small focused spot, small side lobe and homogeneous intensity focused beams in the on-axis and transverse directions, the focal depth of the logarithmic axicon should be 3~5 mm, the apodization radius should be 15~60 mm, and the edge super-Guassian smoothing order should be 5. The long focal depth device whose focal depth was more than 3 mm, axial intensity distribution was uniform and the maximal relative intensity of the side lobe was less than 2% of the center intensity was des
For the laser plasma diagnostic system in the inertial confinement fusion(ICF) drivers, the logarithmic axicon was adopted and improved by fifth-order super-Guassian edge smoothing, centre apodization and choosing suitable device parameters. The simulation experiments indicated that, to obtain a long-focal depth, small focused spot, small side lobe and homogeneous intensity focused beams in the on-axis and transverse directions, the focal depth of the logarithmic axicon should be 3~5 mm, the apodization radius should be 15~60 mm, and the edge super-Guassian smoothing order should be 5. The long focal depth device whose focal depth was more than 3 mm, axial intensity distribution was uniform and the maximal relative intensity of the side lobe was less than 2% of the center intensity was des
2006,
18.
Abstract:
The basic condition required for achieving central ignition is producing a hot spot with 10 keV temperature and 0.3 g/cm2 surface density. Growth of hydrodynamic instability during deceleration phase will destroy the symmetric-drive , reduce the volume of central hot spot and make a harmful effect on ignition. Based on the LARED-S code, considering the thermonuclear reaction and α-particle heating, a numerical study of direct-drive ICF in spherical geometry is made. One-dimensional results agree well with the NIF ignition target designs, and show that the α-particle heating plays an important role in marginal ignition. Two-dimensional results show that the growth of hydrodynamic instability during deceleration phase makes a harmful effect on ignition.
The basic condition required for achieving central ignition is producing a hot spot with 10 keV temperature and 0.3 g/cm2 surface density. Growth of hydrodynamic instability during deceleration phase will destroy the symmetric-drive , reduce the volume of central hot spot and make a harmful effect on ignition. Based on the LARED-S code, considering the thermonuclear reaction and α-particle heating, a numerical study of direct-drive ICF in spherical geometry is made. One-dimensional results agree well with the NIF ignition target designs, and show that the α-particle heating plays an important role in marginal ignition. Two-dimensional results show that the growth of hydrodynamic instability during deceleration phase makes a harmful effect on ignition.
2006,
18.
Abstract:
In this paper, nano-porous silica films are prepared via Sol-Gel process with base, acid and base/acid two-step catalysis. TEM and Particle Size Analyzer are used to characterize the properties of the microstructure and particles size distribution of the sol. FE-SEM, AFM and Spectroscopic Ellipsometer are used to characterize the surface microstructure and optical properties of the film. Structure controlling by changing the catalysis conditions during Sol-Gel process is investigated, and the stability of the sol during long-term storage is studied.
In this paper, nano-porous silica films are prepared via Sol-Gel process with base, acid and base/acid two-step catalysis. TEM and Particle Size Analyzer are used to characterize the properties of the microstructure and particles size distribution of the sol. FE-SEM, AFM and Spectroscopic Ellipsometer are used to characterize the surface microstructure and optical properties of the film. Structure controlling by changing the catalysis conditions during Sol-Gel process is investigated, and the stability of the sol during long-term storage is studied.
2006,
18.
Abstract:
The silica alco-gel was obtained by the 2-step acid-base catalyzed TEOS. Aging in a solution of methyltrimethoxylsilane and trimethylating Si-OH groups increased the strength and stiffness of the wet gel by hexamethyldisilazane (HMDSA) on the surface of silica matrix. The modified silica aerogel was obtainted by CO2 supercritical drying method. The bulk densities of aerogels were between 30~100 mg/cm3. FTIR and some other experiment methods were used to investigate the structure and hydrophobic properties. The experiment results showed that the aerogel possessed perfect size-stability and hydrophobic properties. The aerogel micro-cylinder for ICF targets was manufactured by lathe machine.
The silica alco-gel was obtained by the 2-step acid-base catalyzed TEOS. Aging in a solution of methyltrimethoxylsilane and trimethylating Si-OH groups increased the strength and stiffness of the wet gel by hexamethyldisilazane (HMDSA) on the surface of silica matrix. The modified silica aerogel was obtainted by CO2 supercritical drying method. The bulk densities of aerogels were between 30~100 mg/cm3. FTIR and some other experiment methods were used to investigate the structure and hydrophobic properties. The experiment results showed that the aerogel possessed perfect size-stability and hydrophobic properties. The aerogel micro-cylinder for ICF targets was manufactured by lathe machine.
2006,
18.
Abstract:
The electronic structures of defect of Na substituting for K in KH2PO4 (KDP) crystals are studied by first-principles total-energy calculations based on density-functional theory. The calculated formation energy for this defect is about 0.46 eV. No defect states are induced in the energy gap, whereas two extra occupied states are induced in the valence band, which are located at -49 eV and -21.5 eV below the Fermi energy level, respectively.
The electronic structures of defect of Na substituting for K in KH2PO4 (KDP) crystals are studied by first-principles total-energy calculations based on density-functional theory. The calculated formation energy for this defect is about 0.46 eV. No defect states are induced in the energy gap, whereas two extra occupied states are induced in the valence band, which are located at -49 eV and -21.5 eV below the Fermi energy level, respectively.
2006,
18.
Abstract:
The explosive magnetic generator of frequency is a simple and small device for generating and radiating electromagnetic pulse. To optimize its performance, the mathematical model is researched first, and then the Bessel function which meets the output signal requirement is obtained. The output signal mode and the circuit energy distribution under different electrical parameter are analyzed. The research result shows that when the product of the time during which the inductance changes to 1/e of its initial value and initial carrier frequency is large enough, the output signal of the generator is the oscillation mode. The larger the product is, the higher the carrier frequency is and it is beneficial to the radiation.
The explosive magnetic generator of frequency is a simple and small device for generating and radiating electromagnetic pulse. To optimize its performance, the mathematical model is researched first, and then the Bessel function which meets the output signal requirement is obtained. The output signal mode and the circuit energy distribution under different electrical parameter are analyzed. The research result shows that when the product of the time during which the inductance changes to 1/e of its initial value and initial carrier frequency is large enough, the output signal of the generator is the oscillation mode. The larger the product is, the higher the carrier frequency is and it is beneficial to the radiation.
2006,
18.
Abstract:
An optical imaging diagnostic system was developed for “QiangGuang-I” wire array Z-pinch experiments. The system, with a gate of 5 ns and spatial resolution of 6.5 lp/mm, is sensitive to the wavelength of 365~750 nm. The system can be used to study the whole process of wire array Z-pinch, from the discharge of single wire to the breakdown of plasma column. The last image series of wire array Z-pinch plasma measured by this system are shown and phenomenally discussed.
An optical imaging diagnostic system was developed for “QiangGuang-I” wire array Z-pinch experiments. The system, with a gate of 5 ns and spatial resolution of 6.5 lp/mm, is sensitive to the wavelength of 365~750 nm. The system can be used to study the whole process of wire array Z-pinch, from the discharge of single wire to the breakdown of plasma column. The last image series of wire array Z-pinch plasma measured by this system are shown and phenomenally discussed.
2006,
18.
Abstract:
The technique of using multiresolution-time-domain (MRTD) method to solve the issue of electromagnetic pulse (EMP) coupling to thin wires was researched. Traditional Holland method was applied to MRTD, and a scheme in MRTD was produced to calculate the EMP coupling of thin wire structures. The computational process of the scheme was presented as well as correlative parameters. The result indicates that the maximum space step length which is equal to a quater of the smallest wavelength can be employed in the MRTD scheme with computational resources being saved effectively, MRTD is suitable to deal with the thin wire-EMP coupling in condition of thin wires being laid on ground surface, and the MRTD scheme is a proper way to compute ground-laying thin-wire issue.
The technique of using multiresolution-time-domain (MRTD) method to solve the issue of electromagnetic pulse (EMP) coupling to thin wires was researched. Traditional Holland method was applied to MRTD, and a scheme in MRTD was produced to calculate the EMP coupling of thin wire structures. The computational process of the scheme was presented as well as correlative parameters. The result indicates that the maximum space step length which is equal to a quater of the smallest wavelength can be employed in the MRTD scheme with computational resources being saved effectively, MRTD is suitable to deal with the thin wire-EMP coupling in condition of thin wires being laid on ground surface, and the MRTD scheme is a proper way to compute ground-laying thin-wire issue.
2006,
18.
Abstract:
A multi-pulse generator based on inductive storage and electro-explosive opening switch is introduced in this paper. The generator consists of a capacitor bank used as the primary energy source and an electro-explosive opening switch which is made up of wire arrays with different lengths and different cross-sections. Two or three consecutive pulses are obtained in experiment. The number of pulses is decided by the number of steps of wire arrays. The interval between the pulses and the amplitude of the pulse can be controlled by the parameters of the wire arrays and the output voltage of the capacitor bank.
A multi-pulse generator based on inductive storage and electro-explosive opening switch is introduced in this paper. The generator consists of a capacitor bank used as the primary energy source and an electro-explosive opening switch which is made up of wire arrays with different lengths and different cross-sections. Two or three consecutive pulses are obtained in experiment. The number of pulses is decided by the number of steps of wire arrays. The interval between the pulses and the amplitude of the pulse can be controlled by the parameters of the wire arrays and the output voltage of the capacitor bank.
2006,
18.
Abstract:
X-ray radiation produced by a small gas puff Z-pinch device in Tsinghua University was detected. This device was powered by a 16 mF capacitor bank charged to 230 kV, corresponding to a storage energy of 4.3 kJ, the discharge current reached its peak value of 210 kA at a time of 2.5 ms. The X-ray radiation from a Neon gas puff Z-pinch was measured with a sub-ns rise time PIN detector. The differential signal of discharge current was recorded to determine the pinch point, when the X-ray radiation was emitted. The signals were analyzed and discussed in this paper.
X-ray radiation produced by a small gas puff Z-pinch device in Tsinghua University was detected. This device was powered by a 16 mF capacitor bank charged to 230 kV, corresponding to a storage energy of 4.3 kJ, the discharge current reached its peak value of 210 kA at a time of 2.5 ms. The X-ray radiation from a Neon gas puff Z-pinch was measured with a sub-ns rise time PIN detector. The differential signal of discharge current was recorded to determine the pinch point, when the X-ray radiation was emitted. The signals were analyzed and discussed in this paper.
2006,
18.
Abstract:
In this paper, the quasi-relativistic Hartree-Fock-Relativistic atomic structure code and the unresolved transition array model were used to calculate the dielectronic recombination rate and the electron-ion collisional excitation rate of two high-Z elements:Au and Ta. The calculated results show that for 3d10-3d94l5f-3d104l dielectronic recombination of Ni-like gold ion and 3d104l-3d94l5f electron collisional excitation of Cu-like gold ion, the dielectronic recombination rates tend to rise and the collisional excitation rates tend to fall when electron temperature increases. Furthermore, electron collisional excitation contributes more to the line emission of 5f-3d transition than dielectronic recombination.
In this paper, the quasi-relativistic Hartree-Fock-Relativistic atomic structure code and the unresolved transition array model were used to calculate the dielectronic recombination rate and the electron-ion collisional excitation rate of two high-Z elements:Au and Ta. The calculated results show that for 3d10-3d94l5f-3d104l dielectronic recombination of Ni-like gold ion and 3d104l-3d94l5f electron collisional excitation of Cu-like gold ion, the dielectronic recombination rates tend to rise and the collisional excitation rates tend to fall when electron temperature increases. Furthermore, electron collisional excitation contributes more to the line emission of 5f-3d transition than dielectronic recombination.
2006,
18.
Abstract:
Based on the Dirac-Slater self-consistent-field method, the photoionization cross sections of electrons in 1s, 2s and 2p subshells of carbon atom with different degree of ionization (CI, CII, CIII, CIV, CV, CVI) are calculated from ionization threshold to 300 keV. In the calculation, the multipole and relativistic effects have been included. Variations of cross sections with the photon energy, ionization degree and subshells are investigated. The results are also compared with the data obtained from the Kramers formula with the Gaunt factor correction and the data of Verner et al. The validity of Kramers formula is discussed.
Based on the Dirac-Slater self-consistent-field method, the photoionization cross sections of electrons in 1s, 2s and 2p subshells of carbon atom with different degree of ionization (CI, CII, CIII, CIV, CV, CVI) are calculated from ionization threshold to 300 keV. In the calculation, the multipole and relativistic effects have been included. Variations of cross sections with the photon energy, ionization degree and subshells are investigated. The results are also compared with the data obtained from the Kramers formula with the Gaunt factor correction and the data of Verner et al. The validity of Kramers formula is discussed.
2006,
18.
Abstract:
The synthesis and characterization of mercaptosuccinic acid monolayer protected water-soluble gold clusters (Au MPC) are described. TEM photograph displays that when Au/S mole ratio is 1∶3, size of Au core of MPC is about 2 nm. Results of the FTIR spectra indicate that the mercaptosuccinic acid chains are assembled on the gold cores via the Au-S bond. UV-vis absorbance and luminescence of Au MPC in aqueous media were studied. There is no UV-vis absorbance around 520 nm but visible luminescence around 796 nm at the 451 nm and 480 nm excitation. Absorption band in the visible region around 520 nm reflects the surface plasmon band(SPB) that is due to the collective oscillations of the electron gas at the surface of nanoparticles (6 s electrons of the conduction band for Au MPC). The SPB is a
The synthesis and characterization of mercaptosuccinic acid monolayer protected water-soluble gold clusters (Au MPC) are described. TEM photograph displays that when Au/S mole ratio is 1∶3, size of Au core of MPC is about 2 nm. Results of the FTIR spectra indicate that the mercaptosuccinic acid chains are assembled on the gold cores via the Au-S bond. UV-vis absorbance and luminescence of Au MPC in aqueous media were studied. There is no UV-vis absorbance around 520 nm but visible luminescence around 796 nm at the 451 nm and 480 nm excitation. Absorption band in the visible region around 520 nm reflects the surface plasmon band(SPB) that is due to the collective oscillations of the electron gas at the surface of nanoparticles (6 s electrons of the conduction band for Au MPC). The SPB is a
2006,
18.
Abstract:
The waveguide is used in the whole optical cavity of CAEP far-infrared FEL. The influence of waveguide on the net gain of the optical cavity is estimated by calculating the transverse coupling factor between the optical beam and electron beam. The influence of the waveguide is simulated using 3D code. The simulation experiments have been done by reducing the wave guide gap and enhancing field intensity to increase the optical gain. The results show that the gain can be increased by 7%~15% when the wave-guide gap is reduced by 2 mm, and the net gain can be increased almost by 5%~10% when the magnetic field intensity is enhanced by 0.02 T.
The waveguide is used in the whole optical cavity of CAEP far-infrared FEL. The influence of waveguide on the net gain of the optical cavity is estimated by calculating the transverse coupling factor between the optical beam and electron beam. The influence of the waveguide is simulated using 3D code. The simulation experiments have been done by reducing the wave guide gap and enhancing field intensity to increase the optical gain. The results show that the gain can be increased by 7%~15% when the wave-guide gap is reduced by 2 mm, and the net gain can be increased almost by 5%~10% when the magnetic field intensity is enhanced by 0.02 T.
2006,
18.
Abstract:
To improve the beam performance of the two-bunch acceleration (two macro beam pulses in one macro microwave pulse), a new sub-harmonic bunching system has been designed and optimized for BEPCII Linac. Due to the difference between the new bunching system and the present one, the physical tolerances to the key components must be reconsidered. In this paper, the most important jitter effects in the new bunching system are studied systematically, which include the gun timing，high voltage jitters, the phase and power jitters of the two sub-harmonic bunchers and the phase jitters of the 4-cell traveling wave buncher and A0(accelerating section in the bunching system) accelerating tube. A multi-particle simulation program PARMELA is employed, and the physical tolerances of the jitters have been
To improve the beam performance of the two-bunch acceleration (two macro beam pulses in one macro microwave pulse), a new sub-harmonic bunching system has been designed and optimized for BEPCII Linac. Due to the difference between the new bunching system and the present one, the physical tolerances to the key components must be reconsidered. In this paper, the most important jitter effects in the new bunching system are studied systematically, which include the gun timing，high voltage jitters, the phase and power jitters of the two sub-harmonic bunchers and the phase jitters of the 4-cell traveling wave buncher and A0(accelerating section in the bunching system) accelerating tube. A multi-particle simulation program PARMELA is employed, and the physical tolerances of the jitters have been
2006,
18.
Abstract:
The electromagnetic field of beam energy spread monitor (BESM) with multi-stripline electrodes for BEPCII is calculated by Superfish code. The electromagnetic field computations with simulation beam are used to analyze the relations between the electrode opening angle and the resolutions of beam position and energy-spread and calculate the coupling strength over all the electrodes of the BESM. The optimization design of the electrode opening angle for BESM has been done. Without considering the noise, the BESM with 20° electrode opening angle has the best sensitivity and resolution.
The electromagnetic field of beam energy spread monitor (BESM) with multi-stripline electrodes for BEPCII is calculated by Superfish code. The electromagnetic field computations with simulation beam are used to analyze the relations between the electrode opening angle and the resolutions of beam position and energy-spread and calculate the coupling strength over all the electrodes of the BESM. The optimization design of the electrode opening angle for BESM has been done. Without considering the noise, the BESM with 20° electrode opening angle has the best sensitivity and resolution.
2006,
18.
Abstract:
A series of experiments studying Mo wire X-pinch were carried out on “Yang” facility. This facility generated a peak current of about 520 kA with 80 ns rise time. The X-pinch load was composed of two identical Mo wires with a diameter of 10 μm, 15 μm or 20 μm, crossing at an angle of 32°,45° or 60°. X-ray power meter and X-ray framing camera were utilized to measure the power of the X-ray radiation and take X-ray imaging respectively. The results showed that one or more intense X-ray bursts occured and hot spots emitting X-rays of energy exceeding 3 keV were formed. The smallest hot spot was less than 30 μm in diameter.
A series of experiments studying Mo wire X-pinch were carried out on “Yang” facility. This facility generated a peak current of about 520 kA with 80 ns rise time. The X-pinch load was composed of two identical Mo wires with a diameter of 10 μm, 15 μm or 20 μm, crossing at an angle of 32°,45° or 60°. X-ray power meter and X-ray framing camera were utilized to measure the power of the X-ray radiation and take X-ray imaging respectively. The results showed that one or more intense X-ray bursts occured and hot spots emitting X-rays of energy exceeding 3 keV were formed. The smallest hot spot was less than 30 μm in diameter.
2006,
18.
Abstract:
A low prepulse high power density water dielectric self-breaking switch has been investigated on FlashⅡgenerator recently. The switch contains two or four gaps, a prepulse shield and supporting hardware. The configuration and equivalent circuit model of the switch are introduced while part parameter calculations are provided in this paper. All gaps of the switch were charged approximately linearly from 0 to 1 MV in 60 ns. The discharge current and the input or output voltages of each gap were measured by a Rogowski coil and CuSO4 resistance dividers respectively. The switches with two gaps and four gaps were experimented respectively. The water switch was discharged with a discharge current about 200 to 550 kA after the gaps were charged and had a mean field of 600 to 900 kV/cm. The jitte
A low prepulse high power density water dielectric self-breaking switch has been investigated on FlashⅡgenerator recently. The switch contains two or four gaps, a prepulse shield and supporting hardware. The configuration and equivalent circuit model of the switch are introduced while part parameter calculations are provided in this paper. All gaps of the switch were charged approximately linearly from 0 to 1 MV in 60 ns. The discharge current and the input or output voltages of each gap were measured by a Rogowski coil and CuSO4 resistance dividers respectively. The switches with two gaps and four gaps were experimented respectively. The water switch was discharged with a discharge current about 200 to 550 kA after the gaps were charged and had a mean field of 600 to 900 kV/cm. The jitte
2006,
18.
Abstract:
The phase-space measurement system of Hefei light source was introduced. Three phase-space measurement and calculation methods of the system, two-position-once, one-position-twice and one-position-once were studied and compared. The compared simulation results show that the same phase-space images are obtained by the three methods, but the necessary condition and measurement technology are different.
The phase-space measurement system of Hefei light source was introduced. Three phase-space measurement and calculation methods of the system, two-position-once, one-position-twice and one-position-once were studied and compared. The compared simulation results show that the same phase-space images are obtained by the three methods, but the necessary condition and measurement technology are different.
2006,
18.
Abstract:
Experimental researches on self-breakdown characteristics of three-electrodes repetitive gas switch, including relationship between the self-breakdwon characteristics and gas pressure, gas flow speed and electrode shape, were performed on the accelerator CHP01. The results show that the deviation of self-breakdown voltage of the switch increases greatly as gas pressure rises, and proper gas flow speed is helpful to decrease the deviation but too high gas flow speed may result in greater deviation. It is also revealed that deviation and average value of self-breakdown voltage of the switch decrease as field enhancement factor increases by adjusting the electrode shape.
Experimental researches on self-breakdown characteristics of three-electrodes repetitive gas switch, including relationship between the self-breakdwon characteristics and gas pressure, gas flow speed and electrode shape, were performed on the accelerator CHP01. The results show that the deviation of self-breakdown voltage of the switch increases greatly as gas pressure rises, and proper gas flow speed is helpful to decrease the deviation but too high gas flow speed may result in greater deviation. It is also revealed that deviation and average value of self-breakdown voltage of the switch decrease as field enhancement factor increases by adjusting the electrode shape.
