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RSS2007 Vol. 19, No. 11
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2007,
19.
Abstract:
The series connected circuit structure with synchronous drive technology, which is composed of 12 relatively independent pulse power supplies, is used in order to acquire 10 kV high voltage pulse. The design is modularized and different voltage output can be realized through varying the number of pulse power units. The output parameters of the power supply are as follows: the peak voltage 0.1~10.0 kV, the pulse frequency 0.2~2.0 kHz, the duty cycle 5%~30%, the pulse current magnitude 20 A, and the pulse power 200 kW. Experiments have demonstrated that the power supply is stable and reliable in plasma surface modification processes.
The series connected circuit structure with synchronous drive technology, which is composed of 12 relatively independent pulse power supplies, is used in order to acquire 10 kV high voltage pulse. The design is modularized and different voltage output can be realized through varying the number of pulse power units. The output parameters of the power supply are as follows: the peak voltage 0.1~10.0 kV, the pulse frequency 0.2~2.0 kHz, the duty cycle 5%~30%, the pulse current magnitude 20 A, and the pulse power 200 kW. Experiments have demonstrated that the power supply is stable and reliable in plasma surface modification processes.
2007,
19.
Abstract:
The characteristic resistances of the folded parts of Blumlein line were theoretically calculated by a method based on the unit capacitance and inductance concept, and were numerically calculated based on the equivalent energy. The results of these two methods are nearly accordant and show the characteristic resistance of the folded parts is nearly the same as that of the parallel parts. The electric field intensity distributions of folded parts with different inner radii were simulated, which gives an optimized inner radius of 10 mm. The output waveforms on the match load were also simulated by means of equivalent electric circuit. According to the results of the theoretical analysis and simulation, a Blumlein line of folded parallel-plates configuration with output voltage of 500 kV, pu
The characteristic resistances of the folded parts of Blumlein line were theoretically calculated by a method based on the unit capacitance and inductance concept, and were numerically calculated based on the equivalent energy. The results of these two methods are nearly accordant and show the characteristic resistance of the folded parts is nearly the same as that of the parallel parts. The electric field intensity distributions of folded parts with different inner radii were simulated, which gives an optimized inner radius of 10 mm. The output waveforms on the match load were also simulated by means of equivalent electric circuit. According to the results of the theoretical analysis and simulation, a Blumlein line of folded parallel-plates configuration with output voltage of 500 kV, pu
2007,
19.
Abstract:
The design and experimental results of the 22-stage 4 MV laser-triggered multi-channel switch are reported. The field distribution of the laser-triggered gap and the serial selfbreakdown gaps are symmetrical. The selfbreakdown gap is designed as an annular gap formed by disk electrodes and a column insulator stack. The field distribution of the switch section is regulated by the voltage-holding field regulation ring. The experimental results show that the maximal deviation of the selfbreakdown voltage is less than 5%. The difference between the average selfbreakdown voltage and the linear fit is less than 5%. The switch is triggered by a 4 ns, 35 mJ Nd:YAG fourth harmonic laser pulse. The delay is about 25 ns as the working ratio is 85%±3% of the selfbreakdown voltage. The maximal deviat
The design and experimental results of the 22-stage 4 MV laser-triggered multi-channel switch are reported. The field distribution of the laser-triggered gap and the serial selfbreakdown gaps are symmetrical. The selfbreakdown gap is designed as an annular gap formed by disk electrodes and a column insulator stack. The field distribution of the switch section is regulated by the voltage-holding field regulation ring. The experimental results show that the maximal deviation of the selfbreakdown voltage is less than 5%. The difference between the average selfbreakdown voltage and the linear fit is less than 5%. The switch is triggered by a 4 ns, 35 mJ Nd:YAG fourth harmonic laser pulse. The delay is about 25 ns as the working ratio is 85%±3% of the selfbreakdown voltage. The maximal deviat
2007,
19.
Abstract:
The principle of measuring night-time total atmospheric transmittance with the calibration method of Langley-plot is introduced. Accordingly, a measurement system consisting mainly of a telescope, an intensified CCD, and an imaging data acquiring card has been developed to measure the weak stellar irradiance from level 1 to level 6 during the spectral band of 350~750 nm. The results obtained after calibration have been compared with the simulated value of MODTRAN, which verifies the feasibility of the system’s design.
The principle of measuring night-time total atmospheric transmittance with the calibration method of Langley-plot is introduced. Accordingly, a measurement system consisting mainly of a telescope, an intensified CCD, and an imaging data acquiring card has been developed to measure the weak stellar irradiance from level 1 to level 6 during the spectral band of 350~750 nm. The results obtained after calibration have been compared with the simulated value of MODTRAN, which verifies the feasibility of the system’s design.
2007,
19.
Abstract:
A parameterized design method for secondary nozzle of hypersonic low temperature(HYLTE) nozzle of DF chemical laser was established in order to provide an available approach to optimize HYLTE nozzle. Four basic geometric parameters and two adjusting parameters were selected for the parameterized nozzle design by analyzing the restriction and sensitivity of those parameters which affect the nozzle performance or configuration. The relative unmixedness was introduced to evaluate the mixing performance of the designed nozzle. Furthermore, a 3 dimensional simulation code was built to compute the flowfield of the nozzle and cavity. It is indicated that the primary performance for nozzle evaluating is sensitive to the basic geometric parameters.
A parameterized design method for secondary nozzle of hypersonic low temperature(HYLTE) nozzle of DF chemical laser was established in order to provide an available approach to optimize HYLTE nozzle. Four basic geometric parameters and two adjusting parameters were selected for the parameterized nozzle design by analyzing the restriction and sensitivity of those parameters which affect the nozzle performance or configuration. The relative unmixedness was introduced to evaluate the mixing performance of the designed nozzle. Furthermore, a 3 dimensional simulation code was built to compute the flowfield of the nozzle and cavity. It is indicated that the primary performance for nozzle evaluating is sensitive to the basic geometric parameters.
2007,
19.
Abstract:
Based on the rate equation of electron generation, a simple model of evolution of conduction electron under short pulse laser irradiation is employed to predict the laser damage thresholds of SiO2. The rates of impact ionization and photoionization are calculated and compared with each other. The threshold energy densities are obtained as function of pulse duration from 0.1 ps to 10 ns. The results show that for long pulse, the damage is dominated by impact ionization, and the thresholds are in proportion to the square root of pulse duration. While in the cases of short pulse, the damage is also governed by impact ionization but with photoionization supplying the seed electrons, and with decreasing pulse duration, the threshold first rises，then drops．
Based on the rate equation of electron generation, a simple model of evolution of conduction electron under short pulse laser irradiation is employed to predict the laser damage thresholds of SiO2. The rates of impact ionization and photoionization are calculated and compared with each other. The threshold energy densities are obtained as function of pulse duration from 0.1 ps to 10 ns. The results show that for long pulse, the damage is dominated by impact ionization, and the thresholds are in proportion to the square root of pulse duration. While in the cases of short pulse, the damage is also governed by impact ionization but with photoionization supplying the seed electrons, and with decreasing pulse duration, the threshold first rises，then drops．
2007,
19.
Abstract:
In order to avoid the dynamic thermal-induced depolarization losses which relates to Brewster-angle scheme solid-state heat capacity laser, a laser with a V-shaped active-mirror configuration is developed and tested, using high-quality dichromatic coatings. The transmissivity of pump light is greater than 95% and the reflectivity of laser is greater than 99.7% on the same coating. The output fell down limitedly by time in the condition of repetitive operation with 1 ms pulse, and a pulsed energy output of 47 J was generated with 5 ms pulse width and 9.4 kW peak power. The measured results agree with the calculated ones(10.11 kW) in the same condition as the experiment.
In order to avoid the dynamic thermal-induced depolarization losses which relates to Brewster-angle scheme solid-state heat capacity laser, a laser with a V-shaped active-mirror configuration is developed and tested, using high-quality dichromatic coatings. The transmissivity of pump light is greater than 95% and the reflectivity of laser is greater than 99.7% on the same coating. The output fell down limitedly by time in the condition of repetitive operation with 1 ms pulse, and a pulsed energy output of 47 J was generated with 5 ms pulse width and 9.4 kW peak power. The measured results agree with the calculated ones(10.11 kW) in the same condition as the experiment.
2007,
19.
Abstract:
The mathematical model of coherent combination of super-Gaussian beams is established. When the interval of the coherent emitter arrays is 1 cm, the super-Gaussian order is 12, the beams intensity distribution of coherent combination is about 10 times as that of incoherent combination. The intensity distribution in various conditions is analyzed. The results show that when the random phase error is less than l/10, or the order of the super-Gaussian is more than 10, the beam intensity of the coherent combination hardly changes. When the beams interval increases, the intensity distribution of coherent combination decreases speedily and the beam quality gets worse. With the increase of the propagation distance of beams, the intensity increases and attenuates at last. The intensity distributio
The mathematical model of coherent combination of super-Gaussian beams is established. When the interval of the coherent emitter arrays is 1 cm, the super-Gaussian order is 12, the beams intensity distribution of coherent combination is about 10 times as that of incoherent combination. The intensity distribution in various conditions is analyzed. The results show that when the random phase error is less than l/10, or the order of the super-Gaussian is more than 10, the beam intensity of the coherent combination hardly changes. When the beams interval increases, the intensity distribution of coherent combination decreases speedily and the beam quality gets worse. With the increase of the propagation distance of beams, the intensity increases and attenuates at last. The intensity distributio
2007,
19.
Abstract:
Silicon-CCD is irradiated by 800 nm 100 fs pulsed laser, and the phenomena of saturation, cross-talk and totally damage are observed and corresponding thresholds versus repetitive frequency are measured. Particularly, a new damage phenomenon characterized by a degraded image divided into a bright part and a dark part is observed. Microscope is used to analyze the damage mechanism and it is inferred that the most severe failure could result from the malfunction of CCD circuits because of laser irradiation. Typical results of CCD irradiated by laser out of field of view is also presented.
Silicon-CCD is irradiated by 800 nm 100 fs pulsed laser, and the phenomena of saturation, cross-talk and totally damage are observed and corresponding thresholds versus repetitive frequency are measured. Particularly, a new damage phenomenon characterized by a degraded image divided into a bright part and a dark part is observed. Microscope is used to analyze the damage mechanism and it is inferred that the most severe failure could result from the malfunction of CCD circuits because of laser irradiation. Typical results of CCD irradiated by laser out of field of view is also presented.
2007,
19.
Abstract:
A metallic binary grating with two grooves per period, defined by different linewidths and the same depth, is applied to side-pumping high power fiber lasers for the first time. This kind of doubly grooved metallic grating can be fabricated directly on inner clad of double-clad fiber and so that it can be used for high-power laser pumping. By combining a gradient algorithm (quasi-Newton methods) and micro- genetic algorithm, the grating is optimized and the maximum coupling efficiencies of 94.77% and 77.27% for TM and TE polarization waves respectively are demonstrated. Meanwhile, the fabrication-error and the minimum feature size of grating are also analyzed.
A metallic binary grating with two grooves per period, defined by different linewidths and the same depth, is applied to side-pumping high power fiber lasers for the first time. This kind of doubly grooved metallic grating can be fabricated directly on inner clad of double-clad fiber and so that it can be used for high-power laser pumping. By combining a gradient algorithm (quasi-Newton methods) and micro- genetic algorithm, the grating is optimized and the maximum coupling efficiencies of 94.77% and 77.27% for TM and TE polarization waves respectively are demonstrated. Meanwhile, the fabrication-error and the minimum feature size of grating are also analyzed.
2007,
19.
Abstract:
The propagation property of 1+1 dimensional Gaussian optical beam is investigated in small lossy strongly nonlocal nonlinear media by means of variational method. The evolution equations of the parameters, the beam width evolution law and a critical power are obtained for the beam. In the case of small loss, a lossy optical spatial soliton with beam width slow diffraction is found when the input power equals the critical power. When the input power is smaller than the critical power, the beam width takes quasi-periodical diffraction with the Jacobian elliptic sine and elliptic cosine functions. When the input power is larger than the critical power, it changes from quasi-periodical contraction to diffraction with the same functions.
The propagation property of 1+1 dimensional Gaussian optical beam is investigated in small lossy strongly nonlocal nonlinear media by means of variational method. The evolution equations of the parameters, the beam width evolution law and a critical power are obtained for the beam. In the case of small loss, a lossy optical spatial soliton with beam width slow diffraction is found when the input power equals the critical power. When the input power is smaller than the critical power, the beam width takes quasi-periodical diffraction with the Jacobian elliptic sine and elliptic cosine functions. When the input power is larger than the critical power, it changes from quasi-periodical contraction to diffraction with the same functions.
2007,
19.
Abstract:
The model of fluorescence reabsorption calculation with Monte-Carlo method is proposed, and the fluorescence reabsorption effects of Yb3+:ZBLANP glass are analyzed for a range of sizes. The redshift in the observed fluorescence spectra caused by the fluorescence reabsorption is calculated considering the reflection on the boundary and material size. For cubic Yb3+:ZBLANP glass, the redshift related to the total internal reflection at the surfaces dominates when the material size is small. The redshift of the mean fluorescence wavelength is in the range of 2.6~5.0 nm when the glass size is in the range of 0.1~1.0 cm. The influence of the fluorescence reabsorption on solid fluorescence cooling can be weakened by minishing material size and changing the geometry of the material.
The model of fluorescence reabsorption calculation with Monte-Carlo method is proposed, and the fluorescence reabsorption effects of Yb3+:ZBLANP glass are analyzed for a range of sizes. The redshift in the observed fluorescence spectra caused by the fluorescence reabsorption is calculated considering the reflection on the boundary and material size. For cubic Yb3+:ZBLANP glass, the redshift related to the total internal reflection at the surfaces dominates when the material size is small. The redshift of the mean fluorescence wavelength is in the range of 2.6~5.0 nm when the glass size is in the range of 0.1~1.0 cm. The influence of the fluorescence reabsorption on solid fluorescence cooling can be weakened by minishing material size and changing the geometry of the material.
2007,
19.
Abstract:
Numerical simulation of chemical oxygen iodine laser (COIL) gases flows based on RADICL setup with vapor condensation was carried out, in which the materials and energy sources caused by vapor condensation were incorporated into our 3-D code, and the number density of drops were given. The pressure, temperature, and gain obtained with condensation were compared with those without condensation. It was found that under vapor condensation,the gases temprature and the peak of gain rise near the downstream nozzle throat.
Numerical simulation of chemical oxygen iodine laser (COIL) gases flows based on RADICL setup with vapor condensation was carried out, in which the materials and energy sources caused by vapor condensation were incorporated into our 3-D code, and the number density of drops were given. The pressure, temperature, and gain obtained with condensation were compared with those without condensation. It was found that under vapor condensation,the gases temprature and the peak of gain rise near the downstream nozzle throat.
2007,
19.
Abstract:
It is reported that the mode-locking starting is achieved more quicker by injecting pulses noise into figure-of-eight Yb3+-doped fiber laser. A detailed investigation about this phenomenon is presented in this paper. Analyzing the process of the mode-locking in the cavity, we discover the noise in the cavity does affect the mode-locking starting process of the fiber laser. During the experiment, when the pump power is 214.75 mW, the figure-of-eight Yb3+doped fiber laser without injecting noise can generate locked-pulse in 30～50 seconds; while the pulses with duration of 30 ns, 10 kHz repetition frequency, and 0.2 mW is injected into the cavity, the fiber laser can generate locked-pulse in 1~2 seconds.
It is reported that the mode-locking starting is achieved more quicker by injecting pulses noise into figure-of-eight Yb3+-doped fiber laser. A detailed investigation about this phenomenon is presented in this paper. Analyzing the process of the mode-locking in the cavity, we discover the noise in the cavity does affect the mode-locking starting process of the fiber laser. During the experiment, when the pump power is 214.75 mW, the figure-of-eight Yb3+doped fiber laser without injecting noise can generate locked-pulse in 30～50 seconds; while the pulses with duration of 30 ns, 10 kHz repetition frequency, and 0.2 mW is injected into the cavity, the fiber laser can generate locked-pulse in 1~2 seconds.
2007,
19.
Abstract:
To improve the performance of chemical oxygen-iodine laser(COIL) beam, a three-point dynamic collimation method is proposed, and a resonator auto-alignment system with auto-adjusting function is designed. The system uses position sensitive device(PSD) as the position detecting element, three groups of PZT as the driving element. The coupling model of the system is presented. Multivariable self-adaptation closed-loop decoupling arithmetic is used to design a three-input-three-output decoupling controller, resulting in high precision dynamic alignment and high qualily light beam. Experiments indicate that the collimating range of the system is 4 mrad, the precision is 5 mrad and the frequency response is 20 Hz, which meet the demand of resonator alignment system for COILs.
To improve the performance of chemical oxygen-iodine laser(COIL) beam, a three-point dynamic collimation method is proposed, and a resonator auto-alignment system with auto-adjusting function is designed. The system uses position sensitive device(PSD) as the position detecting element, three groups of PZT as the driving element. The coupling model of the system is presented. Multivariable self-adaptation closed-loop decoupling arithmetic is used to design a three-input-three-output decoupling controller, resulting in high precision dynamic alignment and high qualily light beam. Experiments indicate that the collimating range of the system is 4 mrad, the precision is 5 mrad and the frequency response is 20 Hz, which meet the demand of resonator alignment system for COILs.
2007,
19.
Abstract:
The flow field outside a moving object with high velocity has much influence on the object’s temperature and stress distribution under laser irradiation. The thermo-fluid-mechanical coupling of a moving cylinder with a subsonic velocity is considered, and the temperature and stress field are obtained using finite element method. It is found that there is a high temperature gradient at the region of the heat source. The stress of the material reaches the yielding limit quickly due to the high temperature, and high residual stresses occur in the material. At the inner surface of the cylinder the stress component is compressive at first, and then becomes tensile gradually due to the temperature rise outside the cylinder. Because of the airflow pressure the stress distribution was not symmet
The flow field outside a moving object with high velocity has much influence on the object’s temperature and stress distribution under laser irradiation. The thermo-fluid-mechanical coupling of a moving cylinder with a subsonic velocity is considered, and the temperature and stress field are obtained using finite element method. It is found that there is a high temperature gradient at the region of the heat source. The stress of the material reaches the yielding limit quickly due to the high temperature, and high residual stresses occur in the material. At the inner surface of the cylinder the stress component is compressive at first, and then becomes tensile gradually due to the temperature rise outside the cylinder. Because of the airflow pressure the stress distribution was not symmet
2007,
19.
Abstract:
The energy level structure, the spectrum characteristic and the laser emission characteristic of ytterbium ions were analyzed. A high power cladding-pumped ytterbium-doped fiber laser generating 61.6 W continuous-wave output power at 1.1 μm with 55% slope efficiency was demonstrated. Two diode-laser-stacks (wavelength 915 nm) were used for pumping from the two ends of the fiber. A dichroic mirror with 45° high reflectivity at (1 100±10) nm and high transmissivity at (910±10) nm was used for exporting laser. The cooperative luminescence effect in the ytterbium doped double clad fiber was obtained in the experiment, and the mechanism of this effect was analyzed as the absorption and emission of Yb3+ ion’ pairs.
The energy level structure, the spectrum characteristic and the laser emission characteristic of ytterbium ions were analyzed. A high power cladding-pumped ytterbium-doped fiber laser generating 61.6 W continuous-wave output power at 1.1 μm with 55% slope efficiency was demonstrated. Two diode-laser-stacks (wavelength 915 nm) were used for pumping from the two ends of the fiber. A dichroic mirror with 45° high reflectivity at (1 100±10) nm and high transmissivity at (910±10) nm was used for exporting laser. The cooperative luminescence effect in the ytterbium doped double clad fiber was obtained in the experiment, and the mechanism of this effect was analyzed as the absorption and emission of Yb3+ ion’ pairs.
2007,
19.
Abstract:
A time-space-resolved 1-D X-ray imaging system is developed to investigate the X-ray power distribution with one-dimensional space and continuous time resolution in Z-pinch experiments performed on Angara-5-1 facility. A slit relays the 1-D image of the pinch to a scintillator which converts X-ray to visible light, and the image is subsequently relayed to the cathode of an optical streak camera via an optical fiber array, optical fiber bundles and a lens and finally the time resolved 1-D X-ray distribution is obtained. As the inner plasma reduced the R-T instability of the implosion, the (40+20) double tungsten array implosion had a better axial implosion uniformity and synchronization than the 40 single tungsten array implosion, as well as the higher peak radiated X-ray power. Axial implo
A time-space-resolved 1-D X-ray imaging system is developed to investigate the X-ray power distribution with one-dimensional space and continuous time resolution in Z-pinch experiments performed on Angara-5-1 facility. A slit relays the 1-D image of the pinch to a scintillator which converts X-ray to visible light, and the image is subsequently relayed to the cathode of an optical streak camera via an optical fiber array, optical fiber bundles and a lens and finally the time resolved 1-D X-ray distribution is obtained. As the inner plasma reduced the R-T instability of the implosion, the (40+20) double tungsten array implosion had a better axial implosion uniformity and synchronization than the 40 single tungsten array implosion, as well as the higher peak radiated X-ray power. Axial implo
2007,
19.
Abstract:
The first, second and third order integral diffraction coefficients of TlAP crystal were calibrated at 4B7 X-ray source on Beijing synchrotron radiation facility with photon energy ranging from 2.1 keV to 6.0 keV. It is shown that the peak diffraction coefficients of the TlAP crystal are rather high. The first order integral diffraction coefficient tends to increase with the decreasing photon energy. But in the range of 2.6 keV to 5.4 keV, the integral diffraction coefficient is about 1.53×10-4 rad. The diffraction coefficients decrease gradually as the diffraction order increases. The second order integral diffraction coefficient is only 1/4 of the first order, and the third order is about one magnitude lower than the first order. The calibrated TlAP crystal can be used to quantitatively
The first, second and third order integral diffraction coefficients of TlAP crystal were calibrated at 4B7 X-ray source on Beijing synchrotron radiation facility with photon energy ranging from 2.1 keV to 6.0 keV. It is shown that the peak diffraction coefficients of the TlAP crystal are rather high. The first order integral diffraction coefficient tends to increase with the decreasing photon energy. But in the range of 2.6 keV to 5.4 keV, the integral diffraction coefficient is about 1.53×10-4 rad. The diffraction coefficients decrease gradually as the diffraction order increases. The second order integral diffraction coefficient is only 1/4 of the first order, and the third order is about one magnitude lower than the first order. The calibrated TlAP crystal can be used to quantitatively
2007,
19.
Abstract:
According to the laser conditions of the ninth beam of Shenguang-Ⅱ facility, the characteristics of the laser-driving shockwave propagation in Al-Au impedance-matching target were studied by JB code and multi-step technique, respectively. The experimental results were consistent with the numerical simulation results. The results show that the shockwave’s maximum stable propagation distance in gold decreases rapidly when shock front propagates from aluminum to gold. Therefore, when people design the Al-Au impedance-matching target, they should first select the Au step thickness, in which the shockwave should propagate steadily. The Al step thickness will be selected according to the calculated shockwave velocity ratio of the two materials in impedance-matching target. For the ninth beam o
According to the laser conditions of the ninth beam of Shenguang-Ⅱ facility, the characteristics of the laser-driving shockwave propagation in Al-Au impedance-matching target were studied by JB code and multi-step technique, respectively. The experimental results were consistent with the numerical simulation results. The results show that the shockwave’s maximum stable propagation distance in gold decreases rapidly when shock front propagates from aluminum to gold. Therefore, when people design the Al-Au impedance-matching target, they should first select the Au step thickness, in which the shockwave should propagate steadily. The Al step thickness will be selected according to the calculated shockwave velocity ratio of the two materials in impedance-matching target. For the ninth beam o
2007,
19.
Abstract:
Zr/C8H8 composite filters were made by free-standing Zr filters of DC magnetron sputtering covered by polystyrene (C8H8) films prepared with Dip master 200. Soft X-ray spectral transmittance of the filters was measured in the National Synchrotron Radiation Laboratory. Results indicate that C8H8 film improves the mechanical characteristics of Zr filter and increases fabrication yield by 20%. Furthermore, C8H8 film can efficiently prevent impurities and improve environmental stability of filters.
Zr/C8H8 composite filters were made by free-standing Zr filters of DC magnetron sputtering covered by polystyrene (C8H8) films prepared with Dip master 200. Soft X-ray spectral transmittance of the filters was measured in the National Synchrotron Radiation Laboratory. Results indicate that C8H8 film improves the mechanical characteristics of Zr filter and increases fabrication yield by 20%. Furthermore, C8H8 film can efficiently prevent impurities and improve environmental stability of filters.
2007,
19.
Abstract:
Based on the principle of spatial filter, the wavefront compensation capabilities of the continuous surface deformable mirror with discrete actuators were analyzed. As a high-pass spatial filter, the relationships between the filter function and the deformable mirror’s parameters, such as actuator density, Gaussian index and coupling, were discussed. The simulation result shows that the actuator density is the decisive factor of wavefront compensation and increasing the Gaussian index or the coupling may profit correcting low order aberrations. This indicates that the choice of deformable mirror’s parameters should depend on the incident wavefront in practice.
Based on the principle of spatial filter, the wavefront compensation capabilities of the continuous surface deformable mirror with discrete actuators were analyzed. As a high-pass spatial filter, the relationships between the filter function and the deformable mirror’s parameters, such as actuator density, Gaussian index and coupling, were discussed. The simulation result shows that the actuator density is the decisive factor of wavefront compensation and increasing the Gaussian index or the coupling may profit correcting low order aberrations. This indicates that the choice of deformable mirror’s parameters should depend on the incident wavefront in practice.
2007,
19.
Abstract:
The monolayer zirconia PVD and sol-gel films deposited on K9 glass substrates were prepared with electron beam evaporation method and spin method respectively. Both the films have similar optical thickness. The laser-induced damage threshold (LIDT) of the two kinds of films was measured. The thermal absorption, porous ratio and the surface morphologies of the films were investigated by Stanford photo-thermal solutions, ellipsometer and atomic force microscopy, respectively. Optical microscopy was used to characterize the defects and impurities of the films before laser irradiation and damage morphology after laser irradiation. The experimental results showed that the different damage morphologies of the two kinds of films were relative to their thermal absorption and microstructure. The zi
The monolayer zirconia PVD and sol-gel films deposited on K9 glass substrates were prepared with electron beam evaporation method and spin method respectively. Both the films have similar optical thickness. The laser-induced damage threshold (LIDT) of the two kinds of films was measured. The thermal absorption, porous ratio and the surface morphologies of the films were investigated by Stanford photo-thermal solutions, ellipsometer and atomic force microscopy, respectively. Optical microscopy was used to characterize the defects and impurities of the films before laser irradiation and damage morphology after laser irradiation. The experimental results showed that the different damage morphologies of the two kinds of films were relative to their thermal absorption and microstructure. The zi
2007,
19.
Abstract:
α-C:H thin films were deposited by low-pressure plasma enhanced chemical vapor deposition(LPPCVD) with H2 and Trans-2-butene as source gases. Atomic force microscope and scanning electron microscope images demonstrated the surface morphology of the films deposited under different T2B/H2 flow ratios and pressure. It was found that the root-mean-square roughness was 0.97 nm when the T2B/H2 flow ratio and pressure were 4 and 15 Pa respectively. The FTIR spectrum showed that the structure and composition of the films change with the T2B/H2 flow ratios, and this films mainly contain sp3C—H bonds, which have low T2B/H2 flow ratio and possess more C=C bonds. The UV-VIS spectrum showed that the transmission ratios can reach 98% in the visible light range, the films have strong absorption in the
α-C:H thin films were deposited by low-pressure plasma enhanced chemical vapor deposition(LPPCVD) with H2 and Trans-2-butene as source gases. Atomic force microscope and scanning electron microscope images demonstrated the surface morphology of the films deposited under different T2B/H2 flow ratios and pressure. It was found that the root-mean-square roughness was 0.97 nm when the T2B/H2 flow ratio and pressure were 4 and 15 Pa respectively. The FTIR spectrum showed that the structure and composition of the films change with the T2B/H2 flow ratios, and this films mainly contain sp3C—H bonds, which have low T2B/H2 flow ratio and possess more C=C bonds. The UV-VIS spectrum showed that the transmission ratios can reach 98% in the visible light range, the films have strong absorption in the
2007,
19.
Abstract:
The post-processed technique is a basic method for analyzing X-ray imaging. With the solution of radiation transfer equation of local thermal equation in stationary state and ray tracing method, a post-processed program for X-ray imaging was accomplished. It could reproduce X-ray imaging in ICF implosion. Numerical results of size of compressed core and duration of doped argon and coated sulfur spectrum are coincident with the data of implosion experiments in Shenguang-Ⅱ．
The post-processed technique is a basic method for analyzing X-ray imaging. With the solution of radiation transfer equation of local thermal equation in stationary state and ray tracing method, a post-processed program for X-ray imaging was accomplished. It could reproduce X-ray imaging in ICF implosion. Numerical results of size of compressed core and duration of doped argon and coated sulfur spectrum are coincident with the data of implosion experiments in Shenguang-Ⅱ．
2007,
19.
Abstract:
A ladder cathode S band magnetically insulated transmission line oscillator(MILO) that operates at 2.10 GHz is designed. Proper structure parameters are chosen based on the discussion of dispersion characteristics. The resonant frequency and loaded quality factor are obtained through numerical calculation of the open cavity model of MILO. An output power of 4.35 GW is generated in 2.5 D particle simulation when the input voltage is 523 kV and input current is 49.7 kA. The power efficiency is 16.7%.
A ladder cathode S band magnetically insulated transmission line oscillator(MILO) that operates at 2.10 GHz is designed. Proper structure parameters are chosen based on the discussion of dispersion characteristics. The resonant frequency and loaded quality factor are obtained through numerical calculation of the open cavity model of MILO. An output power of 4.35 GW is generated in 2.5 D particle simulation when the input voltage is 523 kV and input current is 49.7 kA. The power efficiency is 16.7%.
2007,
19.
Abstract:
With the urgent need of high power sources, a design method for power combiner of X-band high power klystron based on microwave theory and EBMA(extended boundary condition modal analysis) is presented in this paper. Power combiner can combine the input from its rectangular arms into one central circular waveguide working in TE01 mode, so the transmission parameter can determine its performance. Using EBMA and CST software, the transmission parameter of the designed 4-to-1 power combiner is calculated as 1 and 0.99, respectively, which can confirm its validity. For 8-to-1 power combiner, a simplified model has been proposed, which makes possible the calculation of gap impedance of an output cavity after its loading.
With the urgent need of high power sources, a design method for power combiner of X-band high power klystron based on microwave theory and EBMA(extended boundary condition modal analysis) is presented in this paper. Power combiner can combine the input from its rectangular arms into one central circular waveguide working in TE01 mode, so the transmission parameter can determine its performance. Using EBMA and CST software, the transmission parameter of the designed 4-to-1 power combiner is calculated as 1 and 0.99, respectively, which can confirm its validity. For 8-to-1 power combiner, a simplified model has been proposed, which makes possible the calculation of gap impedance of an output cavity after its loading.
2007,
19.
Abstract:
A helical rectangular array antenna of 4-element using L-shaped coupled probes is put forward, which is helical rectangular array antenna fed from radial waveguide and can be used to realized the directional rediation of microwave. Theoretical analysis and numerical simulation show that the antenna is subject to the exiting uniform of each elements and the consistency versus frequencies. The directivity is 12.57 dB and the axial ratio at the normal direction is 1.55 at 4.0 GHz. In the range of 3.60 GHz to 4.05 GHz, the directivity is upon 11.6 dB, the axial ratio is below 1.55, and the reflecting coeffiecient is 0.2.
A helical rectangular array antenna of 4-element using L-shaped coupled probes is put forward, which is helical rectangular array antenna fed from radial waveguide and can be used to realized the directional rediation of microwave. Theoretical analysis and numerical simulation show that the antenna is subject to the exiting uniform of each elements and the consistency versus frequencies. The directivity is 12.57 dB and the axial ratio at the normal direction is 1.55 at 4.0 GHz. In the range of 3.60 GHz to 4.05 GHz, the directivity is upon 11.6 dB, the axial ratio is below 1.55, and the reflecting coeffiecient is 0.2.
2007,
19.
Abstract:
This paper discusses the ultra-wide spectrum high power microwave(UWS-HPM) radiation effects, coupling approach, action mechanism and protection methods of specified radio fuze. Radiation experiment has been done on multi-pose fuze using UWS-HPM generator. The experiment indicates that radiation effects are the strongest when the axis of projectile are parallel to the E-field polarization direction of the UWS-HPM. Theoretical analysis and radiation test reveal the coupling mechanism of UWS-HPM energy: the pulse current coupled by the fuze and projectile transmits to fuze executive-circuit through power-supply-circuit of the fuze, rising rate of the pulse current exceeds the dV/dt(critical rate of rise of off-state voltage) of SCR(silicon control rectifier). Adding protection component to e
This paper discusses the ultra-wide spectrum high power microwave(UWS-HPM) radiation effects, coupling approach, action mechanism and protection methods of specified radio fuze. Radiation experiment has been done on multi-pose fuze using UWS-HPM generator. The experiment indicates that radiation effects are the strongest when the axis of projectile are parallel to the E-field polarization direction of the UWS-HPM. Theoretical analysis and radiation test reveal the coupling mechanism of UWS-HPM energy: the pulse current coupled by the fuze and projectile transmits to fuze executive-circuit through power-supply-circuit of the fuze, rising rate of the pulse current exceeds the dV/dt(critical rate of rise of off-state voltage) of SCR(silicon control rectifier). Adding protection component to e
2007,
19.
Abstract:
The coupling effects of HPM to slots with different size were tested and the general coupling characteristics were obtained. The results indicate that the coupling of narrower slots have stronger polarized of electric field. When the lengths of the slots are equivalent to the wave lengths, the coupling effect is the strongest. In the range of band UWB, L, S and X, the narrower the slot is, the weaker the coupling effect is. The coupling effect becomes weaker when the slot becomes deeper. The pulse width of radiation waves has little influence on the coupling effect.
The coupling effects of HPM to slots with different size were tested and the general coupling characteristics were obtained. The results indicate that the coupling of narrower slots have stronger polarized of electric field. When the lengths of the slots are equivalent to the wave lengths, the coupling effect is the strongest. In the range of band UWB, L, S and X, the narrower the slot is, the weaker the coupling effect is. The coupling effect becomes weaker when the slot becomes deeper. The pulse width of radiation waves has little influence on the coupling effect.
2007,
19.
Abstract:
To extend microwave heating applications, researches of microwave deicing have been done. The rectangular horn antennas were designed to match the load of asphalt admixtures, to improve the heated areas and decline unheated areas effectively. Horns autennas with different slopes are designed for numerical analysis and experiment. In the experiments, the input voltage standing wave ratio of these antennas were measured and the contrasts of effects were made after the asphalts mixtures were heated for the same time. The data was analyzed for better use of these horns, and finally the horn antenna with slop angle of 15 degree was detected to fit the request of near asphalt mixtures heating well in deicing．
To extend microwave heating applications, researches of microwave deicing have been done. The rectangular horn antennas were designed to match the load of asphalt admixtures, to improve the heated areas and decline unheated areas effectively. Horns autennas with different slopes are designed for numerical analysis and experiment. In the experiments, the input voltage standing wave ratio of these antennas were measured and the contrasts of effects were made after the asphalts mixtures were heated for the same time. The data was analyzed for better use of these horns, and finally the horn antenna with slop angle of 15 degree was detected to fit the request of near asphalt mixtures heating well in deicing．
2007,
19.
Abstract:
This paper presents an improved Schottky barrier diode model, develops a computational program in which the Rung-Kutta method with 4-order accuracy and the iterative method are used, and obtains the graphics of the conversion efficiency. With the same load, as the input power increases from zero, the conversion efficiency increases fast at the lower input power level, and the diode can work at a high conversion efficiency over a broad power range. With the same input power, as the resistance increases from zero, the conversion efficiency increases to the maximum before decreasing, and each input power level corresponds to one optimum resistance. For the same input power and load, the diode conversion efficiency increases by decreasing the operating frequency. A microwave to DC conversion e
This paper presents an improved Schottky barrier diode model, develops a computational program in which the Rung-Kutta method with 4-order accuracy and the iterative method are used, and obtains the graphics of the conversion efficiency. With the same load, as the input power increases from zero, the conversion efficiency increases fast at the lower input power level, and the diode can work at a high conversion efficiency over a broad power range. With the same input power, as the resistance increases from zero, the conversion efficiency increases to the maximum before decreasing, and each input power level corresponds to one optimum resistance. For the same input power and load, the diode conversion efficiency increases by decreasing the operating frequency. A microwave to DC conversion e
2007,
19.
Abstract:
In this paper the coupling impedance of circular comb slow wave structure is investigated in detail. Some problems in the computer simulation for interaction impedance are investigated, and a new method for the calculation of interaction impedance is proposed. The study leads to the conclusion that the circular comb slow wave structure has an impedance over 1 W at its fundamental mode within a relatively wide band and may interact with the beam effectively. Besides, the inner radius of the structure is 1/4~1/3 times the wavelength, and 5 times larger than that of a helix, implying 25 times of beam current and 25 times of average power compared to a helix. Calculation of interaction shows that a traveling wave tube in Ka band with maximum power of 170 kW may be realized using this kind
In this paper the coupling impedance of circular comb slow wave structure is investigated in detail. Some problems in the computer simulation for interaction impedance are investigated, and a new method for the calculation of interaction impedance is proposed. The study leads to the conclusion that the circular comb slow wave structure has an impedance over 1 W at its fundamental mode within a relatively wide band and may interact with the beam effectively. Besides, the inner radius of the structure is 1/4~1/3 times the wavelength, and 5 times larger than that of a helix, implying 25 times of beam current and 25 times of average power compared to a helix. Calculation of interaction shows that a traveling wave tube in Ka band with maximum power of 170 kW may be realized using this kind
2007,
19.
Abstract:
A terminal voltage control system with a generating voltmeter for electrostatic accelerator was developed. The circuit of the system was designed and made, which mainly consists of a notch filter, a band filter, an error amplifier and a corona control circuit. The notch filter was designed in the type of TT with the notch frequency about 50 Hz.The center frequency of the band filter was 35 Hz with a bandwidth of 60 Hz. The output of the circuit was 0~10 V which was used to control the corona discharge current. The energy spectrum and the radius of the single ion microbeam were measured. The results indicated that the instability of the terminal voltage was obviously eliminated to less 1%, and the spot radius of the single ion microbeam was smaller than previous.
A terminal voltage control system with a generating voltmeter for electrostatic accelerator was developed. The circuit of the system was designed and made, which mainly consists of a notch filter, a band filter, an error amplifier and a corona control circuit. The notch filter was designed in the type of TT with the notch frequency about 50 Hz.The center frequency of the band filter was 35 Hz with a bandwidth of 60 Hz. The output of the circuit was 0~10 V which was used to control the corona discharge current. The energy spectrum and the radius of the single ion microbeam were measured. The results indicated that the instability of the terminal voltage was obviously eliminated to less 1%, and the spot radius of the single ion microbeam was smaller than previous.
2007,
19.
Abstract:
The paper describes optical diagnosis result of 100 μm FEL spontaneous radiation and stimulated radiation experiment based on RF-linac running and briefly introduces 100 μm FEL optic-resonator collimation system. Wavelength spectrum, power energy and pulse structure of radiation signal are measured and diagnosed for requirements of 100 μm FEL experiment research. Ge:Ga photoelectricity detector and FIR-spectrometer measurement system can acquire wavelength spectrum, macro pulse wave of radiation light singal and 115 μm central wavelength of stimulated radiation through analyzing macro pulse of radiation light. Measurement of power and energy of radiation signal with marked Ge:Ga detector acquires mW level power and nJ level energy of marco pulse.
The paper describes optical diagnosis result of 100 μm FEL spontaneous radiation and stimulated radiation experiment based on RF-linac running and briefly introduces 100 μm FEL optic-resonator collimation system. Wavelength spectrum, power energy and pulse structure of radiation signal are measured and diagnosed for requirements of 100 μm FEL experiment research. Ge:Ga photoelectricity detector and FIR-spectrometer measurement system can acquire wavelength spectrum, macro pulse wave of radiation light singal and 115 μm central wavelength of stimulated radiation through analyzing macro pulse of radiation light. Measurement of power and energy of radiation signal with marked Ge:Ga detector acquires mW level power and nJ level energy of marco pulse.
2007,
19.
Abstract:
Many personal factors would influence the result of the focus measurement of linear accelerator using the conventional sandwich method. This paper presents a modified method which applies a film scanning meter to scan the X-ray image film got by sandwich method for obtaining a greyscale distribution, then the full width at half maximum value of greyscale distribution represents the focus size. The method can eliminates disadvantage influence from accelerator radiant field asymmetry by quadratic polynomial fitting and measures peak width at half height instead of stripe statistic.
Many personal factors would influence the result of the focus measurement of linear accelerator using the conventional sandwich method. This paper presents a modified method which applies a film scanning meter to scan the X-ray image film got by sandwich method for obtaining a greyscale distribution, then the full width at half maximum value of greyscale distribution represents the focus size. The method can eliminates disadvantage influence from accelerator radiant field asymmetry by quadratic polynomial fitting and measures peak width at half height instead of stripe statistic.
2007,
19.
Abstract:
Catalyst particles with narrow size distribution were prepared on glass substrate by spin coating method. The surface morphologies of the films were controlled by varying the angular velocity, circumrotate time, and deoxidized temperature. By optimizing synthesis conditions, well-distributed catalyst particles could be obtained, most of which concentrate around 47~62 nm on the catalyst film. Vertically aligned carbon nanotubes were prepared on the above catalyst film by chemical vapor deposition(CVD). The samples were characterized by scanning electron microscope, transmission electron microscope and Raman spectroscope. The results indicate that spin coating is preferable to generally used dripping method in such aspects as producing substrates with low surface roughness, restricting the c
Catalyst particles with narrow size distribution were prepared on glass substrate by spin coating method. The surface morphologies of the films were controlled by varying the angular velocity, circumrotate time, and deoxidized temperature. By optimizing synthesis conditions, well-distributed catalyst particles could be obtained, most of which concentrate around 47~62 nm on the catalyst film. Vertically aligned carbon nanotubes were prepared on the above catalyst film by chemical vapor deposition(CVD). The samples were characterized by scanning electron microscope, transmission electron microscope and Raman spectroscope. The results indicate that spin coating is preferable to generally used dripping method in such aspects as producing substrates with low surface roughness, restricting the c
2007,
19.
Abstract:
Based on the CAS-LIBB facility, the first single ion microbeam of China, this paper discusses the technology and characteristics of two typical single ion microbeam facilities. One is the collimation type which is simpler in structure but lower in precision. The other is electrostatic lens type that is rigorous but with high positioning precision of submicron, which leads the future of single ion microbeam(SIM). Three detection types, front detection, complete front detection and back detection, are judged, and their effects on the count of radiating ions and the beam quality are studied. A new detector with coupled fiber is being developed for CAS-LIBB microbeam. The fast fluorescence detection with online mode is designed. And finally, the future and the application of SIM are concisely
Based on the CAS-LIBB facility, the first single ion microbeam of China, this paper discusses the technology and characteristics of two typical single ion microbeam facilities. One is the collimation type which is simpler in structure but lower in precision. The other is electrostatic lens type that is rigorous but with high positioning precision of submicron, which leads the future of single ion microbeam(SIM). Three detection types, front detection, complete front detection and back detection, are judged, and their effects on the count of radiating ions and the beam quality are studied. A new detector with coupled fiber is being developed for CAS-LIBB microbeam. The fast fluorescence detection with online mode is designed. And finally, the future and the application of SIM are concisely
2007,
19.
Abstract:
Zn ions of dose 1×1017 cm-2 were implanted at 56 keV into ZnO films deposited by sol-gel process. After ion implantation, the as-implanted sample was annealed in argon ambient at different temperatures from 500~900 ℃. The effects of ion implantation and annealing on the structural and optical properties of the ZnO films were investigated by X-ray diffraction patterns, photoluminescence and optical absorption spectra. Measurement results showed that all diffraction peaks were recovered by annealing at 700 ℃. The absorption edge were observed to have a continuous blueshift with increasing annealing temperature when it was less than 600 ℃, while the absorption edge was found to have a gradual redshift with increasing annealing temperature when it exceeded 600 ℃. Both NBE and DLE were enh
Zn ions of dose 1×1017 cm-2 were implanted at 56 keV into ZnO films deposited by sol-gel process. After ion implantation, the as-implanted sample was annealed in argon ambient at different temperatures from 500~900 ℃. The effects of ion implantation and annealing on the structural and optical properties of the ZnO films were investigated by X-ray diffraction patterns, photoluminescence and optical absorption spectra. Measurement results showed that all diffraction peaks were recovered by annealing at 700 ℃. The absorption edge were observed to have a continuous blueshift with increasing annealing temperature when it was less than 600 ℃, while the absorption edge was found to have a gradual redshift with increasing annealing temperature when it exceeded 600 ℃. Both NBE and DLE were enh
