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RSS2016 Vol. 28, No. 10
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2016,
28: 101001.
doi: 10.11884/HPLPB201628.160005
Abstract:
The reliability growth test of iodine pneumatic valve in COIL was actualized, including the discussion of reliability growth model, design of test scheme, and the data analyzing and processing. We proposed the reconstruction measures of iodine pneumatic valve seal assembly and implemented the reliability verification test. The test result shows that the reliability of iodine pneumatic valve has raised obviously after the reliability growth test. The reliability growth model based on iodine pneumatic valve was deduced, which could provide technical support for improving the working reliability of iodine pneumatic valve.
The reliability growth test of iodine pneumatic valve in COIL was actualized, including the discussion of reliability growth model, design of test scheme, and the data analyzing and processing. We proposed the reconstruction measures of iodine pneumatic valve seal assembly and implemented the reliability verification test. The test result shows that the reliability of iodine pneumatic valve has raised obviously after the reliability growth test. The reliability growth model based on iodine pneumatic valve was deduced, which could provide technical support for improving the working reliability of iodine pneumatic valve.
2016,
28: 101002.
doi: 10.11884/HPLPB201628.151275
Abstract:
Based on a porous structure principle, the nano-foam Cu targets were developed with a thickness of 100 m, a porosity of 70%, the density ratio of 30% solids of Cu. Experiments had been carried out on XG-Ⅲ laser facility in Laser Fusion Research Center, China Academy of Engineering Physics. The minimum laser intensity was more than 1.61018 W/cm2 with a duration of 30 fs. A single-photon-counting X-ray CCD was used to measure K spectrum of the X-ray source. The X-ray yield was counted to achieve K peak photons of 2.9108 photossr-1s-1 from femtosecond irradiated nano-foam Cu. The K X-ray conversion efficiency (CE) reaches the maximum value 0.008 38%. Compared to the pressed Cu foil target, the average X-ray yields of nano-foam structures increased by 1.8 times. The results show that nano-foam structure can effectively enhance the energy absorbability of femtosecond laser and improve the conversion efficiency from ultra intense laser to hot electron and X-ray.
Based on a porous structure principle, the nano-foam Cu targets were developed with a thickness of 100 m, a porosity of 70%, the density ratio of 30% solids of Cu. Experiments had been carried out on XG-Ⅲ laser facility in Laser Fusion Research Center, China Academy of Engineering Physics. The minimum laser intensity was more than 1.61018 W/cm2 with a duration of 30 fs. A single-photon-counting X-ray CCD was used to measure K spectrum of the X-ray source. The X-ray yield was counted to achieve K peak photons of 2.9108 photossr-1s-1 from femtosecond irradiated nano-foam Cu. The K X-ray conversion efficiency (CE) reaches the maximum value 0.008 38%. Compared to the pressed Cu foil target, the average X-ray yields of nano-foam structures increased by 1.8 times. The results show that nano-foam structure can effectively enhance the energy absorbability of femtosecond laser and improve the conversion efficiency from ultra intense laser to hot electron and X-ray.
2016,
28: 101003.
doi: 10.11884/HPLPB201628.151273
Abstract:
An uncooled, passively-Q-switched laser with wide-temperature-range is reported. According to the dependences that the wavelength of laser diode drifts with temperature, a superimposed combination of different wavelength points was made. The thermal property was simulated by Ansys and it turns out that the optimized pump structure can meet the requirements of natural cooling. The best reflectivity of output mirror and small-signal transmission of the saturated absorber are confirmed to be 28% and 36%, the output energy and pulse width is 9.8 mJ and 9 ns, respectively. Based on above results, a 1064 nm laser output with single pulse energy of 8.6 mJ and pulse width of 9.7 ns was developed in the temperature range of 35-55 ℃ without refrigerating. The output instability is less than 5% for one array working and 12% for array switching.
An uncooled, passively-Q-switched laser with wide-temperature-range is reported. According to the dependences that the wavelength of laser diode drifts with temperature, a superimposed combination of different wavelength points was made. The thermal property was simulated by Ansys and it turns out that the optimized pump structure can meet the requirements of natural cooling. The best reflectivity of output mirror and small-signal transmission of the saturated absorber are confirmed to be 28% and 36%, the output energy and pulse width is 9.8 mJ and 9 ns, respectively. Based on above results, a 1064 nm laser output with single pulse energy of 8.6 mJ and pulse width of 9.7 ns was developed in the temperature range of 35-55 ℃ without refrigerating. The output instability is less than 5% for one array working and 12% for array switching.
2016,
28: 101004.
doi: 10.11884/HPLPB201628.160021
Abstract:
To increase the measurement distance and sensitivity of laser Doppler velocimeter, the dual-balanced detection receiving system was designed based on Mach-Zehnder ring structure. The SNR expression of balanced detection system based on the balanced light current is derived and simulated. The simulation shows that the SNR of balanced detection is higher than that of the heterodyne detection when quantum conversion efficiency ratio of two detectors ranges from 0.236 to 1, and the signal-to-noise ratio is the highest when the ratio is 1. The simulation results were demonstrated by experiments.
To increase the measurement distance and sensitivity of laser Doppler velocimeter, the dual-balanced detection receiving system was designed based on Mach-Zehnder ring structure. The SNR expression of balanced detection system based on the balanced light current is derived and simulated. The simulation shows that the SNR of balanced detection is higher than that of the heterodyne detection when quantum conversion efficiency ratio of two detectors ranges from 0.236 to 1, and the signal-to-noise ratio is the highest when the ratio is 1. The simulation results were demonstrated by experiments.
2016,
28: 101005.
doi: 10.11884/HPLPB201628.160075
Abstract:
Several ultrafast optical gating techniques based on transient optical Kerr effect are introduced, including traditional optical Kerr birefringence gating technique, transient grating optical gating technique, and transient optical Kerr lens gating techniques. All the techniques are based on pump-probe experimental setup. Utilizing the change of the phase (polarization), propagation direction or the beam divergence of the signal beam induced by the transient modulation of Kerr materials refractive index, the ultrafast time-resolved spectra of the signal beam could be obtained by scanning the pump-probe delay. By comparing their working principles and experimental setups, it is demonstrated that the transient beam deflection optical gating technique has extended measurable probe bandwidth with no requirements of pump-probe polarization configuration and phase matching conditions, thus it can be widely used in ultrafast broadband time-resolved spectroscopy.
Several ultrafast optical gating techniques based on transient optical Kerr effect are introduced, including traditional optical Kerr birefringence gating technique, transient grating optical gating technique, and transient optical Kerr lens gating techniques. All the techniques are based on pump-probe experimental setup. Utilizing the change of the phase (polarization), propagation direction or the beam divergence of the signal beam induced by the transient modulation of Kerr materials refractive index, the ultrafast time-resolved spectra of the signal beam could be obtained by scanning the pump-probe delay. By comparing their working principles and experimental setups, it is demonstrated that the transient beam deflection optical gating technique has extended measurable probe bandwidth with no requirements of pump-probe polarization configuration and phase matching conditions, thus it can be widely used in ultrafast broadband time-resolved spectroscopy.
2016,
28: 101006.
doi: 10.11884/HPLPB201628.160109
Abstract:
This paper reports a new type ofhigh density side injection waveguide laser. The surrounded high-density side injection technology and the specially processed bare gain fiber are applied. When the injected pump power is 320 W, the highest continuous output power 28 W is obtained with the slope efficiency of 20% and the central wavelength is of 1080 nm, which shows that the structure of surrounded side injection is feasible. There is still much room for development of output power and slope efficiency of the novel laser in the future.
This paper reports a new type ofhigh density side injection waveguide laser. The surrounded high-density side injection technology and the specially processed bare gain fiber are applied. When the injected pump power is 320 W, the highest continuous output power 28 W is obtained with the slope efficiency of 20% and the central wavelength is of 1080 nm, which shows that the structure of surrounded side injection is feasible. There is still much room for development of output power and slope efficiency of the novel laser in the future.
2016,
28: 101007.
doi: 10.11884/HPLPB201628.151108
Abstract:
Combining HF etching and differential interference contrast microscopy, this paper directly observes and analyzes the subsurface damages in fused silica optics. It is proved that the differential interference contrast microscopy has higher resolution than bright field microscopy and could detect the shallow scratches and dots. It is also revealed that polishing process would introduce lots of subsurface damages which are always covered by the redeposition layer. Most of the subsurface damages are plastic deformation induced shallow scratches and dots. A few fracture induced deep scratches and pits also exist. It is deduced that larger polishing particles incline to create severer and more subsurface damages.
Combining HF etching and differential interference contrast microscopy, this paper directly observes and analyzes the subsurface damages in fused silica optics. It is proved that the differential interference contrast microscopy has higher resolution than bright field microscopy and could detect the shallow scratches and dots. It is also revealed that polishing process would introduce lots of subsurface damages which are always covered by the redeposition layer. Most of the subsurface damages are plastic deformation induced shallow scratches and dots. A few fracture induced deep scratches and pits also exist. It is deduced that larger polishing particles incline to create severer and more subsurface damages.
2016,
28: 101008.
doi: 10.11884/HPLPB201628.160103
Abstract:
A new imaging method for serial time-encoded amplified microscope is proposed, which eliminates the impact of spectrum ripples in the non-flat spectrum source and non-uniform gain. It can avoid the waste of low-level amplitude in the pulse edge. The time-space-frequency mapping in the optical time-stretch and amplification in the Dispersion Fourier Transform are demonstrated. A 1550 nm mode-locked pulse laser is used to project the USAF-1951 resolution target line by line, which reflects the potential application in micrometer scale and ultrafast imaging field.
A new imaging method for serial time-encoded amplified microscope is proposed, which eliminates the impact of spectrum ripples in the non-flat spectrum source and non-uniform gain. It can avoid the waste of low-level amplitude in the pulse edge. The time-space-frequency mapping in the optical time-stretch and amplification in the Dispersion Fourier Transform are demonstrated. A 1550 nm mode-locked pulse laser is used to project the USAF-1951 resolution target line by line, which reflects the potential application in micrometer scale and ultrafast imaging field.
2016,
28: 102001.
doi: 10.11884/HPLPB201628.150627
Abstract:
X-ray diffraction imaging is capable of realizing near-diffraction-limited spatial resolution. This paper uses analytical and numerical approaches to study and compare Fresnel zone plate (FZP) imaging and projection-type phase contrast imaging of an object backlit by an X-ray source. The energy of X-rays is the Ti K line (4.5 keV) or Cu K line (8 keV). The results show that the spatial resolution of FZP imaging is better than 1 m, and it is beneficial to use a backlighting source of larger size. For high transmission or weak absorption object, FZP imaging does not work well due to poor contrast. In this case, projection-type phase contrast imaging may be applied to achieve a spatial resolution of a few microns. By including higher-order effect that was not considered before, analytical formulae for image intensity and contrast are given. Numerical approaches are also used to study the phase contrast imaging of thin film target with thickness fluctuations or spatial density modulations illuminated by a microfocus X-ray source. In the case of a point source the theoretical contrast of images coincides well with simulation result. The influence of X-ray source size and imaging distance on the images contrast and spatial resolution is discussed. It is indicated that by controlling the source size and changing the distance between the object and the detector, the spatial resolution could be optimized to 1-4 m.
X-ray diffraction imaging is capable of realizing near-diffraction-limited spatial resolution. This paper uses analytical and numerical approaches to study and compare Fresnel zone plate (FZP) imaging and projection-type phase contrast imaging of an object backlit by an X-ray source. The energy of X-rays is the Ti K line (4.5 keV) or Cu K line (8 keV). The results show that the spatial resolution of FZP imaging is better than 1 m, and it is beneficial to use a backlighting source of larger size. For high transmission or weak absorption object, FZP imaging does not work well due to poor contrast. In this case, projection-type phase contrast imaging may be applied to achieve a spatial resolution of a few microns. By including higher-order effect that was not considered before, analytical formulae for image intensity and contrast are given. Numerical approaches are also used to study the phase contrast imaging of thin film target with thickness fluctuations or spatial density modulations illuminated by a microfocus X-ray source. In the case of a point source the theoretical contrast of images coincides well with simulation result. The influence of X-ray source size and imaging distance on the images contrast and spatial resolution is discussed. It is indicated that by controlling the source size and changing the distance between the object and the detector, the spatial resolution could be optimized to 1-4 m.
2016,
28: 102002.
doi: 10.11884/HPLPB201628.160102
Abstract:
Laser-driven neutron sources have potential applications in many fields of science and technology due to ultrahigh neutron flux and ultrashort pulse duration. We simulated the generation of photonuclear neutrons in the full-physical process by use of several numerical simulation codes. At first, we used 1D radiation hydrodynamics code to simulate the process of ultraintense laser prepulse interacting with Cu target, acquiring the preplasma electrons density profile. Then we got hot electrons information by 3D PIC code to simulate ultraintense laser main pulse interacting with the preplasma. At last we acquired the yield, spectrum and angular spectrum of photonuclear neutrons when the hot electrons impinging with Cu target simulated by Monte Carlo code. The simulation results show that the photonuclear neutrons yield up to 1.2108/J can be obtained using ultraintense laser with intensity 1022 W/cm2 interacting with Cu cylinder target whose thickness and diameter are 4 cm.
Laser-driven neutron sources have potential applications in many fields of science and technology due to ultrahigh neutron flux and ultrashort pulse duration. We simulated the generation of photonuclear neutrons in the full-physical process by use of several numerical simulation codes. At first, we used 1D radiation hydrodynamics code to simulate the process of ultraintense laser prepulse interacting with Cu target, acquiring the preplasma electrons density profile. Then we got hot electrons information by 3D PIC code to simulate ultraintense laser main pulse interacting with the preplasma. At last we acquired the yield, spectrum and angular spectrum of photonuclear neutrons when the hot electrons impinging with Cu target simulated by Monte Carlo code. The simulation results show that the photonuclear neutrons yield up to 1.2108/J can be obtained using ultraintense laser with intensity 1022 W/cm2 interacting with Cu cylinder target whose thickness and diameter are 4 cm.
2016,
28: 102003.
doi: 10.11884/HPLPB201628.151246
Abstract:
Seismic fragility analysis brings in fragility curves which show the probability of structural damage due to earthquake as a function of ground motion indices. In order to evaluate the seismic fragility of Shenguang-Ⅲ target building, the paper performs a series of nonlinear time-history analyses on the target building subjected to the Wenchuan earthquake waves supplied by China National Strong Motion Network Center. Besides, the damage index is the maximum interlayer drift angle, and the earthquake intensity index is PGA (Peak Ground Acceleration). Based on the seismic fragility analysis method, the seismic fragility curves and matrix are obtained. At last, the damage probabilities of Shenguang-Ⅲ target building are calculated according to the seismic fragility curves under seismic fortification intensities eight and nine. The result shows that the damage probability of Shenguang-Ⅲ target building is very small.
Seismic fragility analysis brings in fragility curves which show the probability of structural damage due to earthquake as a function of ground motion indices. In order to evaluate the seismic fragility of Shenguang-Ⅲ target building, the paper performs a series of nonlinear time-history analyses on the target building subjected to the Wenchuan earthquake waves supplied by China National Strong Motion Network Center. Besides, the damage index is the maximum interlayer drift angle, and the earthquake intensity index is PGA (Peak Ground Acceleration). Based on the seismic fragility analysis method, the seismic fragility curves and matrix are obtained. At last, the damage probabilities of Shenguang-Ⅲ target building are calculated according to the seismic fragility curves under seismic fortification intensities eight and nine. The result shows that the damage probability of Shenguang-Ⅲ target building is very small.
2016,
28: 103001.
doi: 10.11884/HPLPB201628.150971
Abstract:
In order to guide the engineering commissioning and optimization of feedforward super linear power amplifier, this paper analyzes the feedforward power amplifier linearization performance and optimized parameters when the components are not ideal. First of all, the theoretic numerical relations of the linearity and branch amplitude mismatch, phase mismatch and delay mismatch are derived, without considering the error power amplifier distortion conditions, which is based on the simplified loop model. The relation of cancellation ratio, delay mismatch and linearization bandwidth is derived. Then, the effective cancellation ratio is defined based on considering error power amplifier distortion. The cancellation ability of third order inter-modulation distortion(IMD3) is analyzed in detail. Finally, the optimization theory is analyzed based on the designed feedforward linear power amplifier. The experimental results show that the amplifier linearity improves 36.23 dB.
In order to guide the engineering commissioning and optimization of feedforward super linear power amplifier, this paper analyzes the feedforward power amplifier linearization performance and optimized parameters when the components are not ideal. First of all, the theoretic numerical relations of the linearity and branch amplitude mismatch, phase mismatch and delay mismatch are derived, without considering the error power amplifier distortion conditions, which is based on the simplified loop model. The relation of cancellation ratio, delay mismatch and linearization bandwidth is derived. Then, the effective cancellation ratio is defined based on considering error power amplifier distortion. The cancellation ability of third order inter-modulation distortion(IMD3) is analyzed in detail. Finally, the optimization theory is analyzed based on the designed feedforward linear power amplifier. The experimental results show that the amplifier linearity improves 36.23 dB.
2016,
28: 103002.
doi: 10.11884/HPLPB201628.151206
Abstract:
The device model of AlGaAs/InGaAs high electron mobility transistor(HEMT) low noise amplifier with 0.25 m gate length is established using semiconductor simulation tool and the damage mechanism of 1 GHz microwave injected from gate and drain on HEMT is studied based on various electric field, current density and lattice temperature in device. The simulation results show that when microwave with 40.1 dBm power level is injected from gate, the peak temperature of HEMT will rise with oscillation and achieve the failure level finally. The location beneath the gate close to source is most susceptible to be damaged due to the effect of high current density path and strong electric field. The device responds with different processes when microwave signal with different power level is injected from drain electrode. HEMT would be damaged in the first cycle if the injected power is higher than the threshold. The position near drain electrode is most susceptible to be damaged. Compared with gate injection, its more difficult to damage the device when 1 GHz microwave is injected from drain.
The device model of AlGaAs/InGaAs high electron mobility transistor(HEMT) low noise amplifier with 0.25 m gate length is established using semiconductor simulation tool and the damage mechanism of 1 GHz microwave injected from gate and drain on HEMT is studied based on various electric field, current density and lattice temperature in device. The simulation results show that when microwave with 40.1 dBm power level is injected from gate, the peak temperature of HEMT will rise with oscillation and achieve the failure level finally. The location beneath the gate close to source is most susceptible to be damaged due to the effect of high current density path and strong electric field. The device responds with different processes when microwave signal with different power level is injected from drain electrode. HEMT would be damaged in the first cycle if the injected power is higher than the threshold. The position near drain electrode is most susceptible to be damaged. Compared with gate injection, its more difficult to damage the device when 1 GHz microwave is injected from drain.
2016,
28: 103101.
doi: 10.11884/HPLPB201628.160055
Abstract:
A four-wavelength THz filter based on photonic crystal ring resonators is proposed in the paper, which contains a square dielectric column in each of the two ring resonators and around the column there are four scattering dielectric cylinders. An FDTD-based Rsoft software is used for simulation and the results show that four THz wavelengths (74.813, 76.980, 78.168 and 78.883 m) can be filtered out by changing the structure parameters such as the side length of the internal square dielectric column, scattering media cylinder radius and the coupling medium cylinder radius. The performance of this filter is excellent because of its high transmittance, high Q value and large channel isolation, in which case this filter has important meaning for THz technology application.
A four-wavelength THz filter based on photonic crystal ring resonators is proposed in the paper, which contains a square dielectric column in each of the two ring resonators and around the column there are four scattering dielectric cylinders. An FDTD-based Rsoft software is used for simulation and the results show that four THz wavelengths (74.813, 76.980, 78.168 and 78.883 m) can be filtered out by changing the structure parameters such as the side length of the internal square dielectric column, scattering media cylinder radius and the coupling medium cylinder radius. The performance of this filter is excellent because of its high transmittance, high Q value and large channel isolation, in which case this filter has important meaning for THz technology application.
2016,
28: 103201.
doi: 10.11884/HPLPB201628.160070
Abstract:
The experimental method and apparatus researching on ultra-wide spectrum(UWS) electromagnetic pulse(EMP) coupling through apertures have been established, the electric field of coupling through round holes was measured depending on different pulse width, different diameter and different depth. The method avoids the reflecting field and scattering field in a certain time window. The experimental results show that: for incident pulses of the same amplitude, the coupling field amplitude is inversely proportional to the incident pulse width and the depth of the holes, proportional to the diameter of the holes.
The experimental method and apparatus researching on ultra-wide spectrum(UWS) electromagnetic pulse(EMP) coupling through apertures have been established, the electric field of coupling through round holes was measured depending on different pulse width, different diameter and different depth. The method avoids the reflecting field and scattering field in a certain time window. The experimental results show that: for incident pulses of the same amplitude, the coupling field amplitude is inversely proportional to the incident pulse width and the depth of the holes, proportional to the diameter of the holes.
2016,
28: 104001.
doi: 10.11884/HPLPB201628.160047
Abstract:
X-ray beam hardening is one of the physical processes that degrade the quality of ICT reconstructed images. Commonly, beam hardening artifacts perform as cupping artifacts and streak artifacts. This paper illustrates and demonstrates a new type of beam hardening artifact. It is closely related to the structure of object. In addition, it is obscure between artifacts and real structures due to regular distribution of artifacts. Linear correction method was applied to suppress artifacts. The quality of reconstructed image is increased, and the accuracy of dimensional metrology is also improved.
X-ray beam hardening is one of the physical processes that degrade the quality of ICT reconstructed images. Commonly, beam hardening artifacts perform as cupping artifacts and streak artifacts. This paper illustrates and demonstrates a new type of beam hardening artifact. It is closely related to the structure of object. In addition, it is obscure between artifacts and real structures due to regular distribution of artifacts. Linear correction method was applied to suppress artifacts. The quality of reconstructed image is increased, and the accuracy of dimensional metrology is also improved.
2016,
28: 104101.
doi: 10.11884/HPLPB201628.160108
Abstract:
Low acoustic impedance support layer with a certain thickness between film bulik acoustic resonator (FBAR) and the substrate can form an acoustic isolation layer to prevent sound leakage to the substrate. Carbon-doped oxide(CDO) is a kind of low acoustic impedance material with good temperature compensation for FBAR, and it can be used as acoustic isolation layer between FBAR and the substrate which results in a novel FBAR structure named as CDO-FBAR. In order to analyze whether the properties of CDO-FBAR is degenerated compared with via-hole type FBAR and the required thickness of CDO as acoustic isolation layer, we used multi-physics coupled simulation software to analyze the resonant frequency, the Q (quality factor) value, the effective electromechanical coupling coefficient and S -parameter of the two kinds of FBARs, and to extract longitudinal vibration displacement of CDO-FBAR. The results indicate: the overall resonant frequency of CDO-FBAR is downshift; CDO isolation layer induced parasitic disturbance in S -parameter; because of the increasing acoustic loss, the Q value decreased slightly, and more reduction happened at parallel resonant frequency; and the effective electromechanical coupling coefficient has also reduced slightly; acoustic wave did not completely attenuate until sound wave propagating in the acoustic isolation layer for 9 m, i.e. it needs only 9 m thick CDO material to form an effective acoustic isolation layer between FBAR and the substrate. Thus, the feasibility of the novel CDO-FBAR structure is verified by simulation.
Low acoustic impedance support layer with a certain thickness between film bulik acoustic resonator (FBAR) and the substrate can form an acoustic isolation layer to prevent sound leakage to the substrate. Carbon-doped oxide(CDO) is a kind of low acoustic impedance material with good temperature compensation for FBAR, and it can be used as acoustic isolation layer between FBAR and the substrate which results in a novel FBAR structure named as CDO-FBAR. In order to analyze whether the properties of CDO-FBAR is degenerated compared with via-hole type FBAR and the required thickness of CDO as acoustic isolation layer, we used multi-physics coupled simulation software to analyze the resonant frequency, the Q (quality factor) value, the effective electromechanical coupling coefficient and S -parameter of the two kinds of FBARs, and to extract longitudinal vibration displacement of CDO-FBAR. The results indicate: the overall resonant frequency of CDO-FBAR is downshift; CDO isolation layer induced parasitic disturbance in S -parameter; because of the increasing acoustic loss, the Q value decreased slightly, and more reduction happened at parallel resonant frequency; and the effective electromechanical coupling coefficient has also reduced slightly; acoustic wave did not completely attenuate until sound wave propagating in the acoustic isolation layer for 9 m, i.e. it needs only 9 m thick CDO material to form an effective acoustic isolation layer between FBAR and the substrate. Thus, the feasibility of the novel CDO-FBAR structure is verified by simulation.
2016,
28: 105001.
doi: 10.11884/HPLPB201628.160022
Abstract:
In this paper, a six-stage switch for the electro-magnetically driven experimental facility CQ-7 is developed. The switch is 131 mm tall with a radius of 108 mm, the total gap is 36 mm, and the inductance of the switch is about 40 nH. The simulation of the electric field strength between the electrodes shows that the electric field is uniformly distributed with the non-uniform coefficient 1.14. The characteristic experiment studies of the switch show that, when the switch work with the voltage in plus or minus 100 kV, the peak current is 70 kA, the switch breakdown delay time and jitter are 35 ns and 3 ns respectively. Analyzed by Gaussian function, the self-breakdown probability is less than 110-4 when the switch work with the safety coefficient 80%. The switch can meet the requirements of the development of the electro-magnetically driven experimental facility CQ-7.
In this paper, a six-stage switch for the electro-magnetically driven experimental facility CQ-7 is developed. The switch is 131 mm tall with a radius of 108 mm, the total gap is 36 mm, and the inductance of the switch is about 40 nH. The simulation of the electric field strength between the electrodes shows that the electric field is uniformly distributed with the non-uniform coefficient 1.14. The characteristic experiment studies of the switch show that, when the switch work with the voltage in plus or minus 100 kV, the peak current is 70 kA, the switch breakdown delay time and jitter are 35 ns and 3 ns respectively. Analyzed by Gaussian function, the self-breakdown probability is less than 110-4 when the switch work with the safety coefficient 80%. The switch can meet the requirements of the development of the electro-magnetically driven experimental facility CQ-7.
2016,
28: 105002.
doi: 10.11884/HPLPB201628.150823
Abstract:
Self-discharge biconical antenna is an important part of the compact electromagnetic pulse radiation system, which determines the gap discharge excitation voltage insulation design and far-field output voltage is of great significance for the research of the entire system. This paper presents an indirect method for measurement of antenna discharge excitation voltage by measuring the charging current of pulse source to the antenna. Static antenna is equivalent to a small capacitor. When starting to work, the source of the antenna is charged when the charging voltage reaches a certain level, the discharge gap breakdown, the antenna radiate electromagnetic energy by fast high voltage pulse excitation. The parasitic capacitance of the antenna is measured first, then the charging current of the antenna is measured by a broadband Rogowski coil, and voltage of the antenna can be obtained by integrating the charging current. Compared with a direct measurement, the method does not need to transform the antenna, has no introduction of parasitic parameters, does not affect the test subjects working conditions, and is easy to implement in engineering.
Self-discharge biconical antenna is an important part of the compact electromagnetic pulse radiation system, which determines the gap discharge excitation voltage insulation design and far-field output voltage is of great significance for the research of the entire system. This paper presents an indirect method for measurement of antenna discharge excitation voltage by measuring the charging current of pulse source to the antenna. Static antenna is equivalent to a small capacitor. When starting to work, the source of the antenna is charged when the charging voltage reaches a certain level, the discharge gap breakdown, the antenna radiate electromagnetic energy by fast high voltage pulse excitation. The parasitic capacitance of the antenna is measured first, then the charging current of the antenna is measured by a broadband Rogowski coil, and voltage of the antenna can be obtained by integrating the charging current. Compared with a direct measurement, the method does not need to transform the antenna, has no introduction of parasitic parameters, does not affect the test subjects working conditions, and is easy to implement in engineering.
2016,
28: 105003.
doi: 10.11884/HPLPB201628.160033
Abstract:
Pulse forming lines (PFLs) with build-in spiral lines are presented in this paper, which can prolong the output pulse width of PFL. Thus PFLs consist of one outer PFL for storing energy and another build-in inner PFL. The inner PFL has an inner conductor made of even spiral lines and an outer shielding cylinder with ladder interior surfaces. The outer PFL is compact, which is based on Tesla transformer. One design example of PFLs with Midel7131 synthetic ester dielectric is given in the end of this paper, whose build-in structure combing spiral lines with double nested coaxial lines, and the result indicates that a pulse with 10 GW peak power and 100 ns width can be generated by the 2 m long PFLs with 1 m interior diameter of outer cylinder.
Pulse forming lines (PFLs) with build-in spiral lines are presented in this paper, which can prolong the output pulse width of PFL. Thus PFLs consist of one outer PFL for storing energy and another build-in inner PFL. The inner PFL has an inner conductor made of even spiral lines and an outer shielding cylinder with ladder interior surfaces. The outer PFL is compact, which is based on Tesla transformer. One design example of PFLs with Midel7131 synthetic ester dielectric is given in the end of this paper, whose build-in structure combing spiral lines with double nested coaxial lines, and the result indicates that a pulse with 10 GW peak power and 100 ns width can be generated by the 2 m long PFLs with 1 m interior diameter of outer cylinder.
2016,
28: 105004.
doi: 10.11884/HPLPB201628.151072
Abstract:
A low temperature plasma jet array device using seven single electrodes surrounded with insulated organic glass is designed to study the discharge properties of atmospheric plasma jet. The ambient gas is atmospheric Helium gas, whose flow rate is controlled from 0 L/min to 10 L/min. This discharge device is driven by a sub-microsecond repetitive high voltage pulsed power with the pulse width about 230 ns, the rising edge about 120 ns. Using a repetitive frequency rate about 500 Hz, the high speed photographs are taken and the current pulse width is about 110 ns. The average jet length was measured under the conditions of changing gas flow rate and pulse voltage amplitudes in the experiment, in order to acquire the interactions of every plasma jet discharge. It is found that the average plasma jet length increases with the increasing voltage amplitude when the voltage amplitude is less than 20 kV and that it increases slowly when the voltage amplitude is higher, up to 35 kV. It is also found that the average jet length reaches the maximum when the gas flowrate is at a regular value, that is, the average length decreases if the gas flowrate is over or under the regular range. Besides, it is also discovered that the central electrode discharge is affected extremely by the gas flowrate. The central jet length is almost invisible when the gas flowrate is very high or very low, while the central jet with a weak discharge is longer than the surrounding jets when the gas flow rate is 1 L/min. The main reasons are that the air blocks the jet developing and the central electrode jet channel is impeded by the surrounding jets. It is easier for the surrounding electrode to develop jets.
A low temperature plasma jet array device using seven single electrodes surrounded with insulated organic glass is designed to study the discharge properties of atmospheric plasma jet. The ambient gas is atmospheric Helium gas, whose flow rate is controlled from 0 L/min to 10 L/min. This discharge device is driven by a sub-microsecond repetitive high voltage pulsed power with the pulse width about 230 ns, the rising edge about 120 ns. Using a repetitive frequency rate about 500 Hz, the high speed photographs are taken and the current pulse width is about 110 ns. The average jet length was measured under the conditions of changing gas flow rate and pulse voltage amplitudes in the experiment, in order to acquire the interactions of every plasma jet discharge. It is found that the average plasma jet length increases with the increasing voltage amplitude when the voltage amplitude is less than 20 kV and that it increases slowly when the voltage amplitude is higher, up to 35 kV. It is also found that the average jet length reaches the maximum when the gas flowrate is at a regular value, that is, the average length decreases if the gas flowrate is over or under the regular range. Besides, it is also discovered that the central electrode discharge is affected extremely by the gas flowrate. The central jet length is almost invisible when the gas flowrate is very high or very low, while the central jet with a weak discharge is longer than the surrounding jets when the gas flow rate is 1 L/min. The main reasons are that the air blocks the jet developing and the central electrode jet channel is impeded by the surrounding jets. It is easier for the surrounding electrode to develop jets.
2016,
28: 105005.
doi: 10.11884/HPLPB201628.160032
Abstract:
A compact generator producing a 2.2 ns high-voltage pulse was developed. The pulse was formed by a 27.7 , 0.9 ns pulse forming line (PFL), which was charged by an iron core transformer with a turn ratio of 2∶33.5 and a coefficient of 0.94. Meanwhile, an adjustable self-break oil switch was applied. The principle of triple resonance transformation was employed by adding a 50 pF tuning capacitor and a 1.15 mH inductor between the transformer and the PFL, which leaded to a significant reduction of the duration and peak value of the transformer voltage without reducing that in the PFL. By using transmission lines with impedance overmatched to that of the PFL, the generator delivered a peak voltage of up to 500 kV across an electron beam diode, generating radiation with a dose of 20 milliroentgens per pulse at a distance of 20 cm, which provides an excellent ultra-short radiation pulse source for studies on radiation physics.
A compact generator producing a 2.2 ns high-voltage pulse was developed. The pulse was formed by a 27.7 , 0.9 ns pulse forming line (PFL), which was charged by an iron core transformer with a turn ratio of 2∶33.5 and a coefficient of 0.94. Meanwhile, an adjustable self-break oil switch was applied. The principle of triple resonance transformation was employed by adding a 50 pF tuning capacitor and a 1.15 mH inductor between the transformer and the PFL, which leaded to a significant reduction of the duration and peak value of the transformer voltage without reducing that in the PFL. By using transmission lines with impedance overmatched to that of the PFL, the generator delivered a peak voltage of up to 500 kV across an electron beam diode, generating radiation with a dose of 20 milliroentgens per pulse at a distance of 20 cm, which provides an excellent ultra-short radiation pulse source for studies on radiation physics.
2016,
28: 105006.
doi: 10.11884/HPLPB201628.160068
Abstract:
The experimental equipment used for synthesizing nanopowders via the sub-microseconds electrical explosion of wire was built based on the short discharge circuit of a pulsed capacitor. The particle morphology of the nanopowder was observed by the transmission electron microscope (TEM). The particle size and distribution of the nanopowders were obtained based on the statistics and observation of TEM images. Aluminum nanopowders were produced by electrical exploding aluminum wire in the argon gas, and the influence of the deposited energy on the characteristics of aluminum nanopowders was studied by changing the charging voltage of the capacitor. The results show that the morphology of aluminum nanopowders was mainly dependent on the argon gas pressure rather than deposited energy, and high deposited energy could also narrow the particle size distribution of aluminum nanopowders and reduce the count mean diameter of nanoparticles under the same argon gas pressure. It is indicated that charging voltage of the capacitor is an influential factor in eliminating submicrometer particles. The count mean diameter, the maximum diameter and the fraction of particles with diameter greater than 100 nm of aluminum nanoparticles decrease exponentially with the increasing expansion volume parameter (Ep-1).
The experimental equipment used for synthesizing nanopowders via the sub-microseconds electrical explosion of wire was built based on the short discharge circuit of a pulsed capacitor. The particle morphology of the nanopowder was observed by the transmission electron microscope (TEM). The particle size and distribution of the nanopowders were obtained based on the statistics and observation of TEM images. Aluminum nanopowders were produced by electrical exploding aluminum wire in the argon gas, and the influence of the deposited energy on the characteristics of aluminum nanopowders was studied by changing the charging voltage of the capacitor. The results show that the morphology of aluminum nanopowders was mainly dependent on the argon gas pressure rather than deposited energy, and high deposited energy could also narrow the particle size distribution of aluminum nanopowders and reduce the count mean diameter of nanoparticles under the same argon gas pressure. It is indicated that charging voltage of the capacitor is an influential factor in eliminating submicrometer particles. The count mean diameter, the maximum diameter and the fraction of particles with diameter greater than 100 nm of aluminum nanoparticles decrease exponentially with the increasing expansion volume parameter (Ep-1).
2016,
28: 105101.
doi: 10.11884/HPLPB201628.151251
Abstract:
A circuit model is built to simulate the performance of the Dragon-Ⅱs induction cavity filled with the amorphous magnetic cores. The equivalent capacitances which correlate with the cavity structure are figured out, and the parameters of each magnetic cores circuit module are fixed on by modulating these parameters to make the simulation waveforms match the experiment voltage and current waveforms. With these initialized parameters, the circuit model can simulate the process of the cavitys excitation exactly. The detail of the voltage and current in different positions of the induction cavity, which cannot be probed in experiment, can be worked out by circuit simulation, and it is much useful for structure optimization and fault analysis of the cavity.
A circuit model is built to simulate the performance of the Dragon-Ⅱs induction cavity filled with the amorphous magnetic cores. The equivalent capacitances which correlate with the cavity structure are figured out, and the parameters of each magnetic cores circuit module are fixed on by modulating these parameters to make the simulation waveforms match the experiment voltage and current waveforms. With these initialized parameters, the circuit model can simulate the process of the cavitys excitation exactly. The detail of the voltage and current in different positions of the induction cavity, which cannot be probed in experiment, can be worked out by circuit simulation, and it is much useful for structure optimization and fault analysis of the cavity.
2016,
28: 105102.
doi: 10.11884/HPLPB201628.160034
Abstract:
For accelerator driven sub-critical system (ADS) injector Ⅱ, we designed the data archiving system which is used to gather devices state information and the order given from the central control room at run-time. The system can provide accurate reference information for trouble shooting and data analysis by accelerator maintenance personnel. It is based on Ethernet and running with the EPICS(Experimental Physics and Industrial Control System) environment. It uses channel access protocol (CA) to exchange data with devices. It uses keepalived software to achieve high available MySQL database services, uses the ArchiveEngine of CSS (Control System Studio)as data acquisition tool to store data in the database, and uses the DataBrower plugin in CSS for data query and curve plot. We optimized the archiving database for data query, and developed a run-time monitor program for database server and archive engine by ourselves to make the system more stable. The practical operation proves that the system can meet the user requirement of the ADS injector Ⅱ. The system has the feature of convenient maintenance, to gather the devices data we just need to add the corresponding PV (Process Variable) information into the channel table of the database.
For accelerator driven sub-critical system (ADS) injector Ⅱ, we designed the data archiving system which is used to gather devices state information and the order given from the central control room at run-time. The system can provide accurate reference information for trouble shooting and data analysis by accelerator maintenance personnel. It is based on Ethernet and running with the EPICS(Experimental Physics and Industrial Control System) environment. It uses channel access protocol (CA) to exchange data with devices. It uses keepalived software to achieve high available MySQL database services, uses the ArchiveEngine of CSS (Control System Studio)as data acquisition tool to store data in the database, and uses the DataBrower plugin in CSS for data query and curve plot. We optimized the archiving database for data query, and developed a run-time monitor program for database server and archive engine by ourselves to make the system more stable. The practical operation proves that the system can meet the user requirement of the ADS injector Ⅱ. The system has the feature of convenient maintenance, to gather the devices data we just need to add the corresponding PV (Process Variable) information into the channel table of the database.
2016,
28: 105103.
doi: 10.11884/HPLPB201628.160004
Abstract:
In accelerator driven sub-critical system (ADS) injectorⅡ,the FPGA beam cut technology is designed for accelerator fast protection control system. When a fault signal is detected by the system, the beam can be quickly cut off. And the fault information will be uploaded to implement fault examination and data analysis. The controller based on field programmable gate array could implement optical fiber communication, serial communication and logic level signal output. The optical fiber communication function is used to control an optical chopper to cut off the beam. Serial communication is used for the transmission of real-time status information of the equipment. Moreover, the logic level output signal is designed to control the relay switch signal to protect equipment from damage remotely. According to the onsite test, the response time of beam cut is within 10 s, which reaches the safety design requirements.
In accelerator driven sub-critical system (ADS) injectorⅡ,the FPGA beam cut technology is designed for accelerator fast protection control system. When a fault signal is detected by the system, the beam can be quickly cut off. And the fault information will be uploaded to implement fault examination and data analysis. The controller based on field programmable gate array could implement optical fiber communication, serial communication and logic level signal output. The optical fiber communication function is used to control an optical chopper to cut off the beam. Serial communication is used for the transmission of real-time status information of the equipment. Moreover, the logic level output signal is designed to control the relay switch signal to protect equipment from damage remotely. According to the onsite test, the response time of beam cut is within 10 s, which reaches the safety design requirements.
2016,
28: 105104.
doi: 10.11884/HPLPB201628.160092
Abstract:
The transverse focusing undulators can be used for electron beams of low energy and smaller function. At present, there are some designs on transverse focusing undulators at home and abroad. This paper proposes several transverse focusing undulators of different magnetic structures which are based on the inclined surface of permanent magnet or/and pole blocks. Using the three-dimensional program Radia, the characteristics of focusing field of these undulators were calculated, the relationship between the focusing characteristics with the main parameters was studied, and performance of these undulators were also compared with other existing transverse focusing undulators. The results show that, for both the weak and strong focusing, several undulator schemes with better and simpler structures than the existing transverse focusing undulators were proposed. In addition, the average focusing gradient of weak focusing undulators does not increase significantly with the center magnetic field whereas the average focusing gradient of strong focusing undulators increases obviously with the center magnetic field.
The transverse focusing undulators can be used for electron beams of low energy and smaller function. At present, there are some designs on transverse focusing undulators at home and abroad. This paper proposes several transverse focusing undulators of different magnetic structures which are based on the inclined surface of permanent magnet or/and pole blocks. Using the three-dimensional program Radia, the characteristics of focusing field of these undulators were calculated, the relationship between the focusing characteristics with the main parameters was studied, and performance of these undulators were also compared with other existing transverse focusing undulators. The results show that, for both the weak and strong focusing, several undulator schemes with better and simpler structures than the existing transverse focusing undulators were proposed. In addition, the average focusing gradient of weak focusing undulators does not increase significantly with the center magnetic field whereas the average focusing gradient of strong focusing undulators increases obviously with the center magnetic field.
2016,
28: 106001.
doi: 10.11884/HPLPB201628.151304
Abstract:
The two dimensional sensitive detector based on 10B film is a newly developed thermal neutron detector with the advantages of large sensitive area, good time and position resolution, high n/ inhibition ability, strong ability of anti-radiation, two-dimensional readout and good resistance to the count rate capability. So it is important to carry out the study of the readout method of the two-dimensional position sensitive neutron detector based on the B neutron transfer layer and MWPC structure. In this paper, a readout board based on delay-line readout method is presented. By measuring the time difference between the arriving signals on both sides of delay-line, the original position can be well recovered. By applying a hardwire filter in FPGA, the data rate needs to be transferred can be reduced remarkably. The RMS of the TDC is less than 50 ps. The integral nonlinearity is better than 1.1 LSB, the differential non-linearity is better than 0.5 LSB. The board achieves event rates of 1.3 MHz for periodic signals and the data can be transferred by Gbit ethernet daughter board simultaneously.
The two dimensional sensitive detector based on 10B film is a newly developed thermal neutron detector with the advantages of large sensitive area, good time and position resolution, high n/ inhibition ability, strong ability of anti-radiation, two-dimensional readout and good resistance to the count rate capability. So it is important to carry out the study of the readout method of the two-dimensional position sensitive neutron detector based on the B neutron transfer layer and MWPC structure. In this paper, a readout board based on delay-line readout method is presented. By measuring the time difference between the arriving signals on both sides of delay-line, the original position can be well recovered. By applying a hardwire filter in FPGA, the data rate needs to be transferred can be reduced remarkably. The RMS of the TDC is less than 50 ps. The integral nonlinearity is better than 1.1 LSB, the differential non-linearity is better than 0.5 LSB. The board achieves event rates of 1.3 MHz for periodic signals and the data can be transferred by Gbit ethernet daughter board simultaneously.
2016,
28: 106002.
doi: 10.11884/HPLPB201628.151146
Abstract:
It is difficult to produce the radioactive standard gas source such as 133Xe, which makes the calibration of g spectrometers difficult. The uniform falling velocities of the 133Ba disk source and 137Cs point source were used to calibrate the detection efficiency of 133Xe volume source and 137Cs linear source. The non-uniform falling velocities of 133Ba disk source and 137Cs point source were used to calibrate the detection efficiency of heterogeneous 133Xe volume source and heterogeneous 137Cs linear source. The results show that the detection efficiencies of 133Xe were 0.155 (for f46.8 mm20 mm sample) and 0.143 (for f63.5 mm20 mm sample) respectively, obtained for the uniform falling velocity of the source, and the uncertainty was 8.4% (k=2). The deviation between the efficiency of the heterogeneously distributed volume source and the efficiency of uniform volume source in 14%, and 23% for linear sources. Therefore, the deviation caused by heterogeneity must be corrected.
It is difficult to produce the radioactive standard gas source such as 133Xe, which makes the calibration of g spectrometers difficult. The uniform falling velocities of the 133Ba disk source and 137Cs point source were used to calibrate the detection efficiency of 133Xe volume source and 137Cs linear source. The non-uniform falling velocities of 133Ba disk source and 137Cs point source were used to calibrate the detection efficiency of heterogeneous 133Xe volume source and heterogeneous 137Cs linear source. The results show that the detection efficiencies of 133Xe were 0.155 (for f46.8 mm20 mm sample) and 0.143 (for f63.5 mm20 mm sample) respectively, obtained for the uniform falling velocity of the source, and the uncertainty was 8.4% (k=2). The deviation between the efficiency of the heterogeneously distributed volume source and the efficiency of uniform volume source in 14%, and 23% for linear sources. Therefore, the deviation caused by heterogeneity must be corrected.
2016,
28: 106003.
doi: 10.11884/HPLPB201628.160062
Abstract:
The Cyclotron Injection System of the Wuwei Heavy Ion Medical Machine consists of a cyclotron that has a weight more than 50 tons, an ion source and some auxiliary facilities. As the ion source and the cyclotron use one girder and have a very tight construction, it is difficult to install and align the system. By the aid of a laser tracker and a three-dimensional control network, through step by step survey and alignment from bottom to top, our method improves the work efficiency of alignment and guarantees a 0.10 mm deviation for each finally installed magnet in each direction. The results are better than the installation precision demands of the Heavy Ion Medical Machine. Currently, the cyclotron injection system has been successfully commissioned and the performance is proved well, and some indexes are better than the design targets, which also verify that the method used for this system has a high accuracy and feasibility.
The Cyclotron Injection System of the Wuwei Heavy Ion Medical Machine consists of a cyclotron that has a weight more than 50 tons, an ion source and some auxiliary facilities. As the ion source and the cyclotron use one girder and have a very tight construction, it is difficult to install and align the system. By the aid of a laser tracker and a three-dimensional control network, through step by step survey and alignment from bottom to top, our method improves the work efficiency of alignment and guarantees a 0.10 mm deviation for each finally installed magnet in each direction. The results are better than the installation precision demands of the Heavy Ion Medical Machine. Currently, the cyclotron injection system has been successfully commissioned and the performance is proved well, and some indexes are better than the design targets, which also verify that the method used for this system has a high accuracy and feasibility.
2016,
28: 106004.
doi: 10.11884/HPLPB201628.160036
Abstract:
With excellent mobility and environmental suitability of minitype rotorcraft, which is combined with traditional nuclear radiation detection equipments, a set of airborne radiation monitoring system was implemented by development of hardware and software, application of wireless communication, GPS and nuclear data processing technology. The terrain environmental impact on system can be ignored, and radiation damage to workers can also be avoided well. This paper introduces the configuration, operating principle and several key technical difficulties of the airborne radiation monitoring system, the design of key modules and measurement of dose rate response linear range are described comprehensively. The test result shows that the system can give a real-time and accurate detection on the radiation of environment, which can be used for daily environmental radiation monitoring or searching for lost or orphan gamma ray sources. A new method for nuclear accidents emergency is provided.
With excellent mobility and environmental suitability of minitype rotorcraft, which is combined with traditional nuclear radiation detection equipments, a set of airborne radiation monitoring system was implemented by development of hardware and software, application of wireless communication, GPS and nuclear data processing technology. The terrain environmental impact on system can be ignored, and radiation damage to workers can also be avoided well. This paper introduces the configuration, operating principle and several key technical difficulties of the airborne radiation monitoring system, the design of key modules and measurement of dose rate response linear range are described comprehensively. The test result shows that the system can give a real-time and accurate detection on the radiation of environment, which can be used for daily environmental radiation monitoring or searching for lost or orphan gamma ray sources. A new method for nuclear accidents emergency is provided.
2016,
28: 106005.
doi: 10.11884/HPLPB201628.151181
Abstract:
Based on the analysis of the structure and function of Direct Digital Frequency Synthesizer(DDS), an online measurement system for DDS is developed, which can test functional registers, capture output waveform and power supply current. Verification experiment has been carried out. The results show that the single event effect may cause waveform disturbances, functional interruption of the output waveform, and sudden increase of power current. We consider that the occurrences of single event transient in internal PLL of DDS and upset of functional registers are the leading causes of waveform disturbance. The DAC main function registers upset triggers the output waveform functional interruption, single event latchup causes current increase. This study provides a reference for consolidation and evaluation of domestic DDS devices.
Based on the analysis of the structure and function of Direct Digital Frequency Synthesizer(DDS), an online measurement system for DDS is developed, which can test functional registers, capture output waveform and power supply current. Verification experiment has been carried out. The results show that the single event effect may cause waveform disturbances, functional interruption of the output waveform, and sudden increase of power current. We consider that the occurrences of single event transient in internal PLL of DDS and upset of functional registers are the leading causes of waveform disturbance. The DAC main function registers upset triggers the output waveform functional interruption, single event latchup causes current increase. This study provides a reference for consolidation and evaluation of domestic DDS devices.
2016,
28: 109001.
doi: 10.11884/HPLPB201628.151343
Abstract:
The ions distribution of the Earths plasmasphere is mainly affected by the feature of the Earths magnetosphere. In early studies, its empirical models or semi-empirical models were only based on the data from in situ observation, and used to observe over the quiet period of the Earths magnetosphere. With the advances in the remote sensing technique, it provides an approach for imaging the Earths plasmasphere on a truly globalscale, and calculate its detailed information during the geomagnetic disturbance period or the geomagnetic quiet period. In this paper, we studied the several populated models of the Earths plasmasphere, elaborated their difference in description forms and application range, then gave the method of simulation imaging by the extreme ultraviolet (EUV) sensing technology. In the final, the simulation result of EUV images was given from the 4 viewpoints of the satellite orbit.
The ions distribution of the Earths plasmasphere is mainly affected by the feature of the Earths magnetosphere. In early studies, its empirical models or semi-empirical models were only based on the data from in situ observation, and used to observe over the quiet period of the Earths magnetosphere. With the advances in the remote sensing technique, it provides an approach for imaging the Earths plasmasphere on a truly globalscale, and calculate its detailed information during the geomagnetic disturbance period or the geomagnetic quiet period. In this paper, we studied the several populated models of the Earths plasmasphere, elaborated their difference in description forms and application range, then gave the method of simulation imaging by the extreme ultraviolet (EUV) sensing technology. In the final, the simulation result of EUV images was given from the 4 viewpoints of the satellite orbit.
2016,
28: 109002.
doi: 10.11884/HPLPB201628.160152
Abstract:
Cascaded OPO based on single non-critical phase matching KTA crystal was proposed. The fundamental oscillation at 1.06 m was achieved by LD end-pumped Nd: YVO4 crystal laser, then the non-critical phase matching cut KTA crystal was intra-cavity pumped. The 1.53 m signal light produced by KTA-OPO was confined in the OPO cavity to realize the second OPO conversion in the same KTA crystal. Under 8 W incident diode pump power at 808 nm, a power exceeding 400 mW and slope efficiency of 12.7% at 2.6 m were achieved based on cascaded OPO. Results show that the cascaded KTA-OPO is an efficient way to achieve 2.5-2.7 m pulsed laser.
Cascaded OPO based on single non-critical phase matching KTA crystal was proposed. The fundamental oscillation at 1.06 m was achieved by LD end-pumped Nd: YVO4 crystal laser, then the non-critical phase matching cut KTA crystal was intra-cavity pumped. The 1.53 m signal light produced by KTA-OPO was confined in the OPO cavity to realize the second OPO conversion in the same KTA crystal. Under 8 W incident diode pump power at 808 nm, a power exceeding 400 mW and slope efficiency of 12.7% at 2.6 m were achieved based on cascaded OPO. Results show that the cascaded KTA-OPO is an efficient way to achieve 2.5-2.7 m pulsed laser.
