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RSS2017 Vol. 29, No. 04
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2017,
29: 041001.
doi: 10.11884/HPLPB201729.160509
Abstract:
Chemical etching is one of the major post-processing techniques to improve laser-induced damage performance of fused silica optics, but deposits adhered to the surface of etched optics affect the surface quality, transmission performance and laser-induced damage resistance of fused silica a lot. In this work, optical microscope and atomic force microscope (AFM) were used to characterize the surface morphology of deposits adhered to the etched surface of fused silica. In addition, the formation process of the deposits was analyzed. Energy dispersive X-ray analysis shows that deposits adhered to the surface of etched fused silica are mainly composed of metallic salts of Fe, Ni and Al elements. Damage threshold test results show that the areas with high density deposits on fused silica surfaces have lower damage thresholds than the areas with few deposits. So redeposits adhered to the etched surface have the great influence on laser damage performance of fused silica, they are precursors inducing laser-damage of fused silica.
Chemical etching is one of the major post-processing techniques to improve laser-induced damage performance of fused silica optics, but deposits adhered to the surface of etched optics affect the surface quality, transmission performance and laser-induced damage resistance of fused silica a lot. In this work, optical microscope and atomic force microscope (AFM) were used to characterize the surface morphology of deposits adhered to the etched surface of fused silica. In addition, the formation process of the deposits was analyzed. Energy dispersive X-ray analysis shows that deposits adhered to the surface of etched fused silica are mainly composed of metallic salts of Fe, Ni and Al elements. Damage threshold test results show that the areas with high density deposits on fused silica surfaces have lower damage thresholds than the areas with few deposits. So redeposits adhered to the etched surface have the great influence on laser damage performance of fused silica, they are precursors inducing laser-damage of fused silica.
2017,
29: 041002.
doi: 10.11884/HPLPB201729.160493
Abstract:
A dumbbell-shaped ytterbium-doped all-fiber laser based on Sagnac fiber loop mirror was demonstrated in this paper. Stable multiwavelength laser output was obtained through finely tuning the polarization controller under the pump of 976 nm laser diode. The largest output power was 5.13 W with the degree of polarization being 14.19 dB while the power fluctuation was no bigger than 0.02 W under the pump power of 20.4 W. The corresponding power difference was less than 3 dB among all channels in long-term observations.
A dumbbell-shaped ytterbium-doped all-fiber laser based on Sagnac fiber loop mirror was demonstrated in this paper. Stable multiwavelength laser output was obtained through finely tuning the polarization controller under the pump of 976 nm laser diode. The largest output power was 5.13 W with the degree of polarization being 14.19 dB while the power fluctuation was no bigger than 0.02 W under the pump power of 20.4 W. The corresponding power difference was less than 3 dB among all channels in long-term observations.
2017,
29: 041003.
doi: 10.11884/HPLPB201729.160373
Abstract:
The mechanism of the thermal stress damage and the distribution of plasma were studied in term of anti-reflection fused silica irradiated by 1064 nm laser. Based on the theories of thermal conduction and gas dynamics, theoretical model of thermal stress damage and combustion damage of anti-reflection fused silica induced by millisecond laser was analyzed. Thermal damage, stress damage and laser supported combustion wave of internal space of anti-reflection fused silica was simulated by COMSOL software. The simulation results show that, roughly with in the area of laser beam spot, the temperature increased obviously with large temperature gradient. Thermal expansion of this lasing area was restricted by the other part, causing internal stress of the material, in which radial stress and circumferential stress of upside surface reached their maximum values in the edge of laser spot. Stress damage was generated in irradiation center point or the edge of laser spot, with steady propagation of plasma. Speed of combustion wave gradually decreased with time from its maximum at the initial moment.
The mechanism of the thermal stress damage and the distribution of plasma were studied in term of anti-reflection fused silica irradiated by 1064 nm laser. Based on the theories of thermal conduction and gas dynamics, theoretical model of thermal stress damage and combustion damage of anti-reflection fused silica induced by millisecond laser was analyzed. Thermal damage, stress damage and laser supported combustion wave of internal space of anti-reflection fused silica was simulated by COMSOL software. The simulation results show that, roughly with in the area of laser beam spot, the temperature increased obviously with large temperature gradient. Thermal expansion of this lasing area was restricted by the other part, causing internal stress of the material, in which radial stress and circumferential stress of upside surface reached their maximum values in the edge of laser spot. Stress damage was generated in irradiation center point or the edge of laser spot, with steady propagation of plasma. Speed of combustion wave gradually decreased with time from its maximum at the initial moment.
2017,
29: 041004.
doi: 10.11884/HPLPB201729.160492
Abstract:
According to the principle of longitudinal-mode-selecting by etalon in pulsed single longitudinal laser, the influences of thickness accuracy and position accuracy of various F-P etalons on the performance of longitudinal mode selecting are analyzed quantitatively. In order to compensate the thickness deviation of etalon, the angle detuning of various etalons are calculated. Then the effects of the incident angle deviation on transmittance curve of F-P etalon are investigated. These are important for setting the mechanical structure design, the tolerance of devices, and the adjustment accuracy of the pulsed single longitudinal laser. In the linear-cavity laser with an F-P etalon for mode-selecting, a near-diffraction-limited single longitude pulsed output is obtained. The maximum single pulse output energy is 8.41 J and the pulse width is 32 ns.
According to the principle of longitudinal-mode-selecting by etalon in pulsed single longitudinal laser, the influences of thickness accuracy and position accuracy of various F-P etalons on the performance of longitudinal mode selecting are analyzed quantitatively. In order to compensate the thickness deviation of etalon, the angle detuning of various etalons are calculated. Then the effects of the incident angle deviation on transmittance curve of F-P etalon are investigated. These are important for setting the mechanical structure design, the tolerance of devices, and the adjustment accuracy of the pulsed single longitudinal laser. In the linear-cavity laser with an F-P etalon for mode-selecting, a near-diffraction-limited single longitude pulsed output is obtained. The maximum single pulse output energy is 8.41 J and the pulse width is 32 ns.
2017,
29: 041005.
doi: 10.11884/HPLPB201729.160517
Abstract:
1.83 m laser output was achieved based on the Nd∶YAG transparent ceramic with 4F3/2-4I15/2 transition. Using compact plane-concave cavity, the laser oscillations with strong energy level transitions were suppressed by controlling the loss of stronger transition line based on reasonable cavity mirror coating. At the incident pump power of 14.6 W, 1.83 m laser with output power of 0.65 W and slope efficiency of 5.8% was obtained by the laser diode end pumped Nd∶YAG ceramic system. Therefore, Nd∶YAG is expected to be a laser medium for directly output 1.83 m laser wavelength.
1.83 m laser output was achieved based on the Nd∶YAG transparent ceramic with 4F3/2-4I15/2 transition. Using compact plane-concave cavity, the laser oscillations with strong energy level transitions were suppressed by controlling the loss of stronger transition line based on reasonable cavity mirror coating. At the incident pump power of 14.6 W, 1.83 m laser with output power of 0.65 W and slope efficiency of 5.8% was obtained by the laser diode end pumped Nd∶YAG ceramic system. Therefore, Nd∶YAG is expected to be a laser medium for directly output 1.83 m laser wavelength.
2017,
29: 042001.
doi: 10.11884/HPLPB201729.160506
Abstract:
This paper reports an ultraviolet laser four-framing shadow imaging system based on the laser with a pulse width of 16ns, a wavelength of 266 nm, a total energy of 30 mJ and a temporal resolution of 1.6 ns, which is used to study the transport laws of the interaction of Z-pinch generated plasmas with the plastic foam located at the center of the wire array and the main physical factors affecting the formation of the dynamic hohlraum. The high-energy and high-density laser beam is used to transmit through the plasmas. The spatial density distribution of the plasmas can be obtained by theoretically calculating the spatial intensity distribution of the laser beam after passing through the plasmas, which is diagnosed based on the plasmas absorption and attenuation characteristic to the laser beam. With the spatial density distribution of the plasmas, the laws of the early stability of the generated plasmas, pinch velocity, and so forth can be obtained. Experimental study indicated that plastic foam was compressed by the plasmas starting at about -25 ns before the X ray peak and was compressed to the minimum diameter at -5 ns before the peak. After that, the foam started to expand. At the X ray peak, the foam diameter was compressed from 3 mm to about 1 mm. The maximum compression ratio of the foam is about 9. The compression velocity measured by the experiment was about 3.3106 cm/s, and the unstable structure distribution of the magnetic fluid at different time is given.
This paper reports an ultraviolet laser four-framing shadow imaging system based on the laser with a pulse width of 16ns, a wavelength of 266 nm, a total energy of 30 mJ and a temporal resolution of 1.6 ns, which is used to study the transport laws of the interaction of Z-pinch generated plasmas with the plastic foam located at the center of the wire array and the main physical factors affecting the formation of the dynamic hohlraum. The high-energy and high-density laser beam is used to transmit through the plasmas. The spatial density distribution of the plasmas can be obtained by theoretically calculating the spatial intensity distribution of the laser beam after passing through the plasmas, which is diagnosed based on the plasmas absorption and attenuation characteristic to the laser beam. With the spatial density distribution of the plasmas, the laws of the early stability of the generated plasmas, pinch velocity, and so forth can be obtained. Experimental study indicated that plastic foam was compressed by the plasmas starting at about -25 ns before the X ray peak and was compressed to the minimum diameter at -5 ns before the peak. After that, the foam started to expand. At the X ray peak, the foam diameter was compressed from 3 mm to about 1 mm. The maximum compression ratio of the foam is about 9. The compression velocity measured by the experiment was about 3.3106 cm/s, and the unstable structure distribution of the magnetic fluid at different time is given.
2017,
29: 043001.
doi: 10.11884/HPLPB201729.160494
Abstract:
The protective suits model on human were established on the basis of the perfect electric conductor and the dimensions of a Chinese male. By means of finite-difference time-domain method, the protective characteristics of the protective suits were studied and the influence of the leakage microwave energy caused by the gap on suits were discussed in detail. The calculation results show that the energy leakage is more likely to happen when the electric field vectors are vertical to the gap. It is found that reduction of whole body average specific absorption rate(WBSAR) in cases of vertical incidence and horizontal incidence is significant when wearing protective suits. The shielding effectiveness(SE) of the protective suits increases with the increase of electromagnetic field frequency (from 300 MHz to 3 GHz), and finally becomes stable. Since the gap is inevitable, special treatment need to be performed to avoid the leakage of energy because SE of the protective suits with gap cannot reach 30 dB.
The protective suits model on human were established on the basis of the perfect electric conductor and the dimensions of a Chinese male. By means of finite-difference time-domain method, the protective characteristics of the protective suits were studied and the influence of the leakage microwave energy caused by the gap on suits were discussed in detail. The calculation results show that the energy leakage is more likely to happen when the electric field vectors are vertical to the gap. It is found that reduction of whole body average specific absorption rate(WBSAR) in cases of vertical incidence and horizontal incidence is significant when wearing protective suits. The shielding effectiveness(SE) of the protective suits increases with the increase of electromagnetic field frequency (from 300 MHz to 3 GHz), and finally becomes stable. Since the gap is inevitable, special treatment need to be performed to avoid the leakage of energy because SE of the protective suits with gap cannot reach 30 dB.
2017,
29: 043201.
doi: 10.11884/HPLPB201729.160528
Abstract:
In order to study the irradiation effects on switching power supply and communication station, an experiment is carried out by using out-band continuous wave as jamming signal. The effect of restart appears when the communication station is under out-of-band strong field interference. The main reason is the influence of out-of-band continuous wave jamming on the normal operation of switching power supply, which results in its output voltage drop. When the power supplys voltage drops to a certain extent, the station will be shut down. Eliminating the interference, the station will restart and turn back to normal station automatically. As equipment under test(EUT), the switching power supply and communication station have various susceptibility to continuous wave jamming at frequency from 20 to 100 MHz. When the jamming signal frequency is 70 MHz, the EUT is most susceptible. And the half wavelength of the 70 MHz signal is similar to the cable length, which indicates that the coupling channel here is the cable. The station is ineffective to sensitive frequency and critical interference E-field strength as a frequency equipment.
In order to study the irradiation effects on switching power supply and communication station, an experiment is carried out by using out-band continuous wave as jamming signal. The effect of restart appears when the communication station is under out-of-band strong field interference. The main reason is the influence of out-of-band continuous wave jamming on the normal operation of switching power supply, which results in its output voltage drop. When the power supplys voltage drops to a certain extent, the station will be shut down. Eliminating the interference, the station will restart and turn back to normal station automatically. As equipment under test(EUT), the switching power supply and communication station have various susceptibility to continuous wave jamming at frequency from 20 to 100 MHz. When the jamming signal frequency is 70 MHz, the EUT is most susceptible. And the half wavelength of the 70 MHz signal is similar to the cable length, which indicates that the coupling channel here is the cable. The station is ineffective to sensitive frequency and critical interference E-field strength as a frequency equipment.
2017,
29: 044001.
doi: 10.11884/HPLPB201729.160481
Abstract:
In the disposal of nuclear waste, regulation and classification of transuranium elements, alpha radioactivity monitoring work in special places such as nuclear arsenal, we usually use the alpha energy spectrum measuring technique. Alpha energy spectrum measurement is one of the key measurements of nuclear radiation, which occupies an important position in the field of nuclear radiation monitoring. In order to accurately analyze the impact of different source-detector distance, vacuum degree, placement angle and other factors on alpha energy spectrum measurement, we used Monte Carlo method to simulate energy spectrum measurement, thus reduced experiment time and improved the accuracy. The Monte Carlo method was used to establish chamber model for the PIPS-alpha spectrometer, which, by changing the distance between a radiation source and detector, simulates the alpha energy spectrum. The simulation results are corrected according to the experimental results to improve the degree of agreement between experiment and simulation. Experiments show that the Monte Carlo model is accurate and can be used for simulating the impact of different source-detector-distance, vacuum degree, placement angle and other factors on alpha energy spectrum measurement. This method not can only be applied to other alpha energy spectrum measurement, but also be used in single energy spectrum research of alpha particles. The study is to provide a basis for the alpha spectrum measurement technology and data support for alpha spectrum technology.
In the disposal of nuclear waste, regulation and classification of transuranium elements, alpha radioactivity monitoring work in special places such as nuclear arsenal, we usually use the alpha energy spectrum measuring technique. Alpha energy spectrum measurement is one of the key measurements of nuclear radiation, which occupies an important position in the field of nuclear radiation monitoring. In order to accurately analyze the impact of different source-detector distance, vacuum degree, placement angle and other factors on alpha energy spectrum measurement, we used Monte Carlo method to simulate energy spectrum measurement, thus reduced experiment time and improved the accuracy. The Monte Carlo method was used to establish chamber model for the PIPS-alpha spectrometer, which, by changing the distance between a radiation source and detector, simulates the alpha energy spectrum. The simulation results are corrected according to the experimental results to improve the degree of agreement between experiment and simulation. Experiments show that the Monte Carlo model is accurate and can be used for simulating the impact of different source-detector-distance, vacuum degree, placement angle and other factors on alpha energy spectrum measurement. This method not can only be applied to other alpha energy spectrum measurement, but also be used in single energy spectrum research of alpha particles. The study is to provide a basis for the alpha spectrum measurement technology and data support for alpha spectrum technology.
2017,
29: 044002.
doi: 10.11884/HPLPB201729.160519
Abstract:
The detected samples of ICT have variable sizes. Maximizing the imaging area of detector is meaningful. This paper uses detector offset to enlarge the FOV, and derives appropriate reconstruction algorithm. The algorithm uses Parker type function weighted redundant portion of the projection data first, then uses fan-beam filtered backprojection reconstruction algorithm to obtain a tomographic image. In experiment, we used an actual industrial CT system to collect projection data of a steel line-to-block and an aluminum alloy gearbox shell to verify the reconstruction algorithm. The reconstructed results prove the correctness and validity of the proposed algorithm, and the spatial resolution is consistent with the reconstructed result of standard scan, and the detector offset method can be used effectively in industrial CT imaging.
The detected samples of ICT have variable sizes. Maximizing the imaging area of detector is meaningful. This paper uses detector offset to enlarge the FOV, and derives appropriate reconstruction algorithm. The algorithm uses Parker type function weighted redundant portion of the projection data first, then uses fan-beam filtered backprojection reconstruction algorithm to obtain a tomographic image. In experiment, we used an actual industrial CT system to collect projection data of a steel line-to-block and an aluminum alloy gearbox shell to verify the reconstruction algorithm. The reconstructed results prove the correctness and validity of the proposed algorithm, and the spatial resolution is consistent with the reconstructed result of standard scan, and the detector offset method can be used effectively in industrial CT imaging.
2017,
29: 044003.
doi: 10.11884/HPLPB201729.160485
Abstract:
In order to research the effect of ion thrusters work performance parameters on output characteristics, an ion thrusters input/output work performance parameter control model was built by theoretical equation, which was also used to calculate work performance parameters of the 30 cm diameter ion thruster and the 20 cm diameter ion thruster. Thrust measure experiment was carried out to verify the calculation results. The verification results indicate that, after doubly charged xenon ion ratio, beam current density and thrust minimum mean squared error were introduced in thrust correction, thrust theoretical calculation values are in rough agreement with the experimental results. The calculation error is less than 1 mN compared with the experimental results, which proves that the thrust correction method used in this paper is reasonable. Ion thruster input/output performance parameter control model provides reference to semi-physical simulation modeling process, and it can be used in thruster work performance parameters optimization and in electrical supply parameters and propellant supply parameters confirm during electrical system united experiment as well.
In order to research the effect of ion thrusters work performance parameters on output characteristics, an ion thrusters input/output work performance parameter control model was built by theoretical equation, which was also used to calculate work performance parameters of the 30 cm diameter ion thruster and the 20 cm diameter ion thruster. Thrust measure experiment was carried out to verify the calculation results. The verification results indicate that, after doubly charged xenon ion ratio, beam current density and thrust minimum mean squared error were introduced in thrust correction, thrust theoretical calculation values are in rough agreement with the experimental results. The calculation error is less than 1 mN compared with the experimental results, which proves that the thrust correction method used in this paper is reasonable. Ion thruster input/output performance parameter control model provides reference to semi-physical simulation modeling process, and it can be used in thruster work performance parameters optimization and in electrical supply parameters and propellant supply parameters confirm during electrical system united experiment as well.
2017,
29: 044101.
doi: 10.11884/HPLPB201729.160521
Abstract:
Due to the single, heavy and time-consuming testing task and the uncertain errors of manual operation of MEMS vector hydrophone sensitivity testing, this paper uses AD9850, AD8599, PGA205, MK60DN512ZVLQ110 micro-controller chips, to design an auto testing device of MEMS vector hydrophone sensitivity based on the analysis of the testing principle of vector hydrophone sensitivity. This device integrates signal excitation source, weak signal detection, signal conditioning, sampling and transmission module. It shrinks testing instrument, integrates multi module and connects PC to make quick and timely calibration testing of vector hydrophone sensitivity, which not only saves testing time greatly, but also can optimize the hydrophone rapidly. It has the advantages of small size, lightweight and simple testing, which brings convenience to field testing and accelerate engineering application of MEMS vector hydrophone.
Due to the single, heavy and time-consuming testing task and the uncertain errors of manual operation of MEMS vector hydrophone sensitivity testing, this paper uses AD9850, AD8599, PGA205, MK60DN512ZVLQ110 micro-controller chips, to design an auto testing device of MEMS vector hydrophone sensitivity based on the analysis of the testing principle of vector hydrophone sensitivity. This device integrates signal excitation source, weak signal detection, signal conditioning, sampling and transmission module. It shrinks testing instrument, integrates multi module and connects PC to make quick and timely calibration testing of vector hydrophone sensitivity, which not only saves testing time greatly, but also can optimize the hydrophone rapidly. It has the advantages of small size, lightweight and simple testing, which brings convenience to field testing and accelerate engineering application of MEMS vector hydrophone.
2017,
29: 044102.
doi: 10.11884/HPLPB201729.160514
Abstract:
Bismuth tungstate (Bi2WO6) shielding material was prepared by a simple solvothermal method without any surfactants and the effects of pyridine, mannitol, polyethylene glycol, ethylene glycol on it were systematically researched. The crystalline phase, compositions, morphology, surface area and band gap energy of the Bi2WO6 were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy absorption spectra. It was found that the solvent had a significant influence on the morphology, photoluminescence properties and radiation shielding properties of the samples. The solvent pyridine enhanced the crystallinity, photoluminescence intensity and -ray shielding properties. PS/Bi2WO6 of irregular nanosphere exhibited -ray shielding rate of 54.17% at a mixed 155Eu and 22Na point source of 105.310 keV, which was much higher than that of conventional shielding materials like PbWO4.
Bismuth tungstate (Bi2WO6) shielding material was prepared by a simple solvothermal method without any surfactants and the effects of pyridine, mannitol, polyethylene glycol, ethylene glycol on it were systematically researched. The crystalline phase, compositions, morphology, surface area and band gap energy of the Bi2WO6 were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy absorption spectra. It was found that the solvent had a significant influence on the morphology, photoluminescence properties and radiation shielding properties of the samples. The solvent pyridine enhanced the crystallinity, photoluminescence intensity and -ray shielding properties. PS/Bi2WO6 of irregular nanosphere exhibited -ray shielding rate of 54.17% at a mixed 155Eu and 22Na point source of 105.310 keV, which was much higher than that of conventional shielding materials like PbWO4.
2017,
29: 045001.
doi: 10.11884/HPLPB201729.160442
Abstract:
As the existing pulse source can not balance pulse width and amplitude, a scheme of based on field effect transistor (MOSFET) and step recovery diode (SRD) combined with picosecond pulse source was put forward. Analyzing traditional designs of several pulse sources, we designed a high repetition rate picosecond pulse generator of 100 volt level and made a design simulation with PSPICE and developed the pulse source PCB board. Measurement shows 2 MHz repetition rate, half amplitude width 400 ps around, range above 110 V and stable waveform. The scheme providedes a new selection for high resolution UWB detection radar transmitter.
As the existing pulse source can not balance pulse width and amplitude, a scheme of based on field effect transistor (MOSFET) and step recovery diode (SRD) combined with picosecond pulse source was put forward. Analyzing traditional designs of several pulse sources, we designed a high repetition rate picosecond pulse generator of 100 volt level and made a design simulation with PSPICE and developed the pulse source PCB board. Measurement shows 2 MHz repetition rate, half amplitude width 400 ps around, range above 110 V and stable waveform. The scheme providedes a new selection for high resolution UWB detection radar transmitter.
2017,
29: 045002.
doi: 10.11884/HPLPB201729.160475
Abstract:
This paper designs a all-solid-state pulse source with the output capability of repetition frequency and fast rise time, using MOSFET semiconductor switch instead of spark gap switch as primary discharge switch and power diode instead of charging resistor to reduce power dissipation. The pulse source has five stages, each stage includes 5 MOSFETs, which are triggered by a pulsed isolated transformer. Under repetition frequency 1 Hz-1 kHz, charge voltage 4-5 kV and load resistor 1 k, the pulse source can output a high voltage pulse with amplitude more than 20 kV, rise time less than 10 ns, pulse width more than 100 ns. The paper gives the experimental results of output high voltage pulses with repetition frequency of 1Hz and 1 kHz, which verify the feasibility of design principle and method.
This paper designs a all-solid-state pulse source with the output capability of repetition frequency and fast rise time, using MOSFET semiconductor switch instead of spark gap switch as primary discharge switch and power diode instead of charging resistor to reduce power dissipation. The pulse source has five stages, each stage includes 5 MOSFETs, which are triggered by a pulsed isolated transformer. Under repetition frequency 1 Hz-1 kHz, charge voltage 4-5 kV and load resistor 1 k, the pulse source can output a high voltage pulse with amplitude more than 20 kV, rise time less than 10 ns, pulse width more than 100 ns. The paper gives the experimental results of output high voltage pulses with repetition frequency of 1Hz and 1 kHz, which verify the feasibility of design principle and method.
2017,
29: 045003.
doi: 10.11884/HPLPB201729.160482
Abstract:
Magnetically driven flyer plate experiments, shot 151 with 370 m thick aluminum flyer plate, carried out in the large current pulse device PTS are simulated and anlayzed with the two-dimensional magneto-hydrodynamics code MDSC2. Numerical simulation shows that the material of the whole flyer plate melts or evaporates due to ablation. Density of the material near the free surface and the loading surface of the flyer plate is low, however, that of the remaining part between the free surface and the loading surface is high. This finding tells us that the velocity measured by VISAR in the experiments may not be the velocity of the liquid-solid interface but be the velocity of the solid density reflecting interface, since the laser of the VISAR will penetrate through the free surface part whose density is lower than that of the solid density reflecting interface and reflect back at the solid density reflecting interface. This idea is confirmed by the coincidence of the simulated velocity of the solid density reflecting interface and the velocity measured by the VISAR.
Magnetically driven flyer plate experiments, shot 151 with 370 m thick aluminum flyer plate, carried out in the large current pulse device PTS are simulated and anlayzed with the two-dimensional magneto-hydrodynamics code MDSC2. Numerical simulation shows that the material of the whole flyer plate melts or evaporates due to ablation. Density of the material near the free surface and the loading surface of the flyer plate is low, however, that of the remaining part between the free surface and the loading surface is high. This finding tells us that the velocity measured by VISAR in the experiments may not be the velocity of the liquid-solid interface but be the velocity of the solid density reflecting interface, since the laser of the VISAR will penetrate through the free surface part whose density is lower than that of the solid density reflecting interface and reflect back at the solid density reflecting interface. This idea is confirmed by the coincidence of the simulated velocity of the solid density reflecting interface and the velocity measured by the VISAR.
2017,
29: 045004.
doi: 10.11884/HPLPB201729.160504
Abstract:
In the paper, a compact pulsed power source based on dielectric line is designed, with the output power more than 4 GW, pulse width 150 ns, and total volume 0.5 m3. The pulsed power source adopts module design, and it is composed of the charring unit, the dielectric line modules and the switches. The energy is stored in Kapton film of the dielectric line. To repress the electromagnetic coupling and take into consideration of the surface insulation, 30 mm is chosen for the distance between two adjacent turns. The height of switch is 45 mm after optimization, with the inductance of which 16.2 nH. In order to decrease the inductance of the system, the connecting electrodes of the dielectric line module are pressed within the switchs electrode. The insulator within the electrodes is 60 layers of Kapton dielectric film, whose total thickness is 2 mm, but can withstand voltage more than 100 kV.
In the paper, a compact pulsed power source based on dielectric line is designed, with the output power more than 4 GW, pulse width 150 ns, and total volume 0.5 m3. The pulsed power source adopts module design, and it is composed of the charring unit, the dielectric line modules and the switches. The energy is stored in Kapton film of the dielectric line. To repress the electromagnetic coupling and take into consideration of the surface insulation, 30 mm is chosen for the distance between two adjacent turns. The height of switch is 45 mm after optimization, with the inductance of which 16.2 nH. In order to decrease the inductance of the system, the connecting electrodes of the dielectric line module are pressed within the switchs electrode. The insulator within the electrodes is 60 layers of Kapton dielectric film, whose total thickness is 2 mm, but can withstand voltage more than 100 kV.
2017,
29: 045101.
doi: 10.11884/HPLPB201729.160538
Abstract:
Induction synchrotron has been a focus of improving the intensity of high energy ion beams. The principle experiments of this new acceleration concept have been done by the Japans High Energy Accelerator Research Organization (KEK). In this paper, a Matlab program has been build to simulate the longitude dynamics of the induction synchrotron, based on the parameters and results of the principle experiments. The simulation results are in accordance with the theoretical analysis and experiment results. The causes of the beam loss problems in the principle experiments are analyzed by simulation and some advices for future improvements of induction synchrotron are proposed.
Induction synchrotron has been a focus of improving the intensity of high energy ion beams. The principle experiments of this new acceleration concept have been done by the Japans High Energy Accelerator Research Organization (KEK). In this paper, a Matlab program has been build to simulate the longitude dynamics of the induction synchrotron, based on the parameters and results of the principle experiments. The simulation results are in accordance with the theoretical analysis and experiment results. The causes of the beam loss problems in the principle experiments are analyzed by simulation and some advices for future improvements of induction synchrotron are proposed.
2017,
29: 045102.
doi: 10.11884/HPLPB201729.160477
Abstract:
Nowadays, the demands for compact, stable and reliable electron accelerators with energies ranging from several hundred keV to a few MeV are growing tremendously, especially the RF electron linacs in the MeV energy range. In this situation, Institute of High Energy Physics(IHEP) is developing an S-band 6 MeV side coupled electron linac. This paper presents the start-to-end simulation studies on this linac. The electron gun and the side coupled accelerating structure were modeled by EGUN and HFSS, respectively. By introducing the electron beam parameters calculated by EGUN and the 3D RF electromagnetic data of HFSS simulation into PARMELA, multi-particle beam dynamics studies for the linac were carried out. The simulation results show that the beam quality at the linac exit is acceptable. A 3D RF design of the side coupled accelerating structure was also investigated by taking the beam loading effect into consideration.
Nowadays, the demands for compact, stable and reliable electron accelerators with energies ranging from several hundred keV to a few MeV are growing tremendously, especially the RF electron linacs in the MeV energy range. In this situation, Institute of High Energy Physics(IHEP) is developing an S-band 6 MeV side coupled electron linac. This paper presents the start-to-end simulation studies on this linac. The electron gun and the side coupled accelerating structure were modeled by EGUN and HFSS, respectively. By introducing the electron beam parameters calculated by EGUN and the 3D RF electromagnetic data of HFSS simulation into PARMELA, multi-particle beam dynamics studies for the linac were carried out. The simulation results show that the beam quality at the linac exit is acceptable. A 3D RF design of the side coupled accelerating structure was also investigated by taking the beam loading effect into consideration.
2017,
29: 046001.
doi: 10.11884/HPLPB201729.160423
Abstract:
With the great improvement of computer performance, analyzing the complex flow and heat transfer phenomena under transient condition by coupling CFD and neutronics has attracted lots of attention nowadays. We developed a neutronics-thermal hydraulics coupled code for transient analysis of pool type lead cooled fast reactors based on FLUENT UDF. The coupled code FLUENT/PK was validated by critical and sub-critical reactor under unprotected transient condition. The validation results show the correctness and feasibility of CFD method in safety analysis of reactors. The coupled code was used to analyze the lead cooled fast reactor SNCLFR-100 (which had been proposed by USTC) under different transient conditions. The calculated results show that there exists great difference if the introducing time of reactivity is different. The sensitivities of the feedback factors were analysed for the reason that these factors will be quite different at different operation time of the reactor core, and the result shows that Doppler constant has the most important effect on reactor safety compared with coolant temperature coefficient, fuel rod axial expansion coefficient and cladding expansion coefficient.
With the great improvement of computer performance, analyzing the complex flow and heat transfer phenomena under transient condition by coupling CFD and neutronics has attracted lots of attention nowadays. We developed a neutronics-thermal hydraulics coupled code for transient analysis of pool type lead cooled fast reactors based on FLUENT UDF. The coupled code FLUENT/PK was validated by critical and sub-critical reactor under unprotected transient condition. The validation results show the correctness and feasibility of CFD method in safety analysis of reactors. The coupled code was used to analyze the lead cooled fast reactor SNCLFR-100 (which had been proposed by USTC) under different transient conditions. The calculated results show that there exists great difference if the introducing time of reactivity is different. The sensitivities of the feedback factors were analysed for the reason that these factors will be quite different at different operation time of the reactor core, and the result shows that Doppler constant has the most important effect on reactor safety compared with coolant temperature coefficient, fuel rod axial expansion coefficient and cladding expansion coefficient.
2017,
29: 046002.
doi: 10.11884/HPLPB201729.160438
Abstract:
EAST poloidal field power supply has been recently implemented the upgrade of control system. The console system is an important subsystem of the control system which can real-time monitor and control PF power supply running status and fault, supports multi-user configuration operation and has a good cross-platform portability and scalability. Inspired by the ITER Control, Data Access and Communication (CODAC), researchers chose Experimental Physics and Industrial Control System (EPICS) as the control system. HMI was developed by Control System Studio(CSS). The console system has been used in poloidal field(PF) control system for the entire 2015 EAST campaign, it had good performance during experiments and convenient human-machine interface.
EAST poloidal field power supply has been recently implemented the upgrade of control system. The console system is an important subsystem of the control system which can real-time monitor and control PF power supply running status and fault, supports multi-user configuration operation and has a good cross-platform portability and scalability. Inspired by the ITER Control, Data Access and Communication (CODAC), researchers chose Experimental Physics and Industrial Control System (EPICS) as the control system. HMI was developed by Control System Studio(CSS). The console system has been used in poloidal field(PF) control system for the entire 2015 EAST campaign, it had good performance during experiments and convenient human-machine interface.
2017,
29: 046003.
doi: 10.11884/HPLPB201729.160466
Abstract:
Hall sensors sensitivity drift as temperature vibrates limits its applications in magnetic measurement field. Common temperature compensation techniques mainly offset drift caused by first order temperature variation and simultaneously neglect error caused by second order temperature variation. In this paper, a circuit design is proposed adopting temperature transducer output signal to offset temperature drift through closed-loop feedback. Temperature transducer output signal multiplied by final output signal from signal processing circuit is sent to input port of signal processing circuit. This is distinguished from universal method of adding temperature transducer output signal with input signal of Hall element and then sending it to input port of signal processing circuit .Theoretical analysis and simulation certify that error caused by temperature drift can be eliminated entirely through equalizing feedback factor K to thermal drift factor of Hall element. Therefore, by thermal drift compensation method of closed-loop feedback, first order and second order temperature variations can be compensated through adjusting feedback coefficient. And this method can be applied to other transducers concerning thermal drift.
Hall sensors sensitivity drift as temperature vibrates limits its applications in magnetic measurement field. Common temperature compensation techniques mainly offset drift caused by first order temperature variation and simultaneously neglect error caused by second order temperature variation. In this paper, a circuit design is proposed adopting temperature transducer output signal to offset temperature drift through closed-loop feedback. Temperature transducer output signal multiplied by final output signal from signal processing circuit is sent to input port of signal processing circuit. This is distinguished from universal method of adding temperature transducer output signal with input signal of Hall element and then sending it to input port of signal processing circuit .Theoretical analysis and simulation certify that error caused by temperature drift can be eliminated entirely through equalizing feedback factor K to thermal drift factor of Hall element. Therefore, by thermal drift compensation method of closed-loop feedback, first order and second order temperature variations can be compensated through adjusting feedback coefficient. And this method can be applied to other transducers concerning thermal drift.
2017,
29: 046005.
doi: 10.11884/HPLPB201729.160273
Abstract:
Stochastic sampling method is used in this paper to study the influence of the uncertainty of multigroup nuclear data on reactor physics calculation. Random values for the nuclear data such as multigroup microscopic cross-sections are generated by sampling the AMPX multigroup library using the self-developed SAMP module and the covariance matrix of SCALE software. Lattice calculations and the steady core calculations are then performed by SCALE and PARCS respectively. The uncertainties of lattice and core calculation results are obtained by statistical analysis accordingly. Taking the fuel assembly and first cycle core of Almaraz PWR plant as the objects, the uncertainties of lattice calculation results such as effective multiplication factor, kinetic parameter, nuclide concentration and two-group macroscopic cross section, and the uncertainties of steady core calculation results like core power distribution are analyzed. The results indicate that the assembly parameters are dependent on the fuel burnup, and the maximum uncertainty of steady core radial power distribution is about 1.9%.
Stochastic sampling method is used in this paper to study the influence of the uncertainty of multigroup nuclear data on reactor physics calculation. Random values for the nuclear data such as multigroup microscopic cross-sections are generated by sampling the AMPX multigroup library using the self-developed SAMP module and the covariance matrix of SCALE software. Lattice calculations and the steady core calculations are then performed by SCALE and PARCS respectively. The uncertainties of lattice and core calculation results are obtained by statistical analysis accordingly. Taking the fuel assembly and first cycle core of Almaraz PWR plant as the objects, the uncertainties of lattice calculation results such as effective multiplication factor, kinetic parameter, nuclide concentration and two-group macroscopic cross section, and the uncertainties of steady core calculation results like core power distribution are analyzed. The results indicate that the assembly parameters are dependent on the fuel burnup, and the maximum uncertainty of steady core radial power distribution is about 1.9%.
2017,
29: 049001.
doi: 10.11884/HPLPB201729.160474
Abstract:
This paper reports the formation of different periodic structures on Ti surface irradiated by 800 nm femtosecond laser pulses in air and water.In air, low spatial frequency periodic structures with period of 500-560 nm are obtained with high laser fluence irradiation; high spatial frequency periodic structures with period of 220-340 nm are obtained with low laser fluence irradiation.All of them are perpendicular to the laser polarization and the period of the structures increases with pulse numbers.In water, not only high spatial frequency periodic structures (215-250 nm) with direction perpendicular to the laser polarization are obtained, but also high spatial frequency periodic structures (about one eighth of laser wavelength) with direction parallel to the laser polarization are obtained.Combined with the surface plasmon polaritons, second harmonic generation and the Sipe model to interpret different periodic structures formation mechanism, we found that the formation of periodic structures is related to the titanium oxide layer.
This paper reports the formation of different periodic structures on Ti surface irradiated by 800 nm femtosecond laser pulses in air and water.In air, low spatial frequency periodic structures with period of 500-560 nm are obtained with high laser fluence irradiation; high spatial frequency periodic structures with period of 220-340 nm are obtained with low laser fluence irradiation.All of them are perpendicular to the laser polarization and the period of the structures increases with pulse numbers.In water, not only high spatial frequency periodic structures (215-250 nm) with direction perpendicular to the laser polarization are obtained, but also high spatial frequency periodic structures (about one eighth of laser wavelength) with direction parallel to the laser polarization are obtained.Combined with the surface plasmon polaritons, second harmonic generation and the Sipe model to interpret different periodic structures formation mechanism, we found that the formation of periodic structures is related to the titanium oxide layer.
2017,
29: 046004.
doi: 10.11884/HPLPB201729.160295
Abstract:
The lattice code is an important component of the nuclear design code system. It generates tabulated cross section sets for reactor neutronics calculations. The development and improvement of lattice codes are always significant topics in reactor physics. The PANDA code is a PWR lattice code developed by Shanghai Nuclear Engineering Research and Design Institute (SNERDI). In PANDA, the one-step calculation flow based on Method of Characteristics(MOC) is utilized, which means the 2D heterogeneous transport calculation is performed without any group collapse and cell homogenization. The multi-group library is processed from the evaluated nuclear data library ENDF/B-VI under a 70-group energy structure, and an improved version based on the ENDF/B-VII library is under development. The Spatially Dependent Dancoff Method (SDDM) is applied to treat the resonance self-shielding phenomena. It supports concentric sub-ring mesh divisions in a fuel pellet, but still preserves the same level of efficiency as the conventional Stammler method. Modular 2D MOC with two-level Coarse Mesh Finite Difference (CMFD) acceleration is used as the heterogeneous transport solver, which has favorable accuracy and efficiency. Various matrix exponential methods are studied to solve the Bateman burnup equation. The PANDA code is developed on the basis of these methodologies. The numerical results preliminarily demonstrate that the PANDA code has the basic ability for engineering computations.
The lattice code is an important component of the nuclear design code system. It generates tabulated cross section sets for reactor neutronics calculations. The development and improvement of lattice codes are always significant topics in reactor physics. The PANDA code is a PWR lattice code developed by Shanghai Nuclear Engineering Research and Design Institute (SNERDI). In PANDA, the one-step calculation flow based on Method of Characteristics(MOC) is utilized, which means the 2D heterogeneous transport calculation is performed without any group collapse and cell homogenization. The multi-group library is processed from the evaluated nuclear data library ENDF/B-VI under a 70-group energy structure, and an improved version based on the ENDF/B-VII library is under development. The Spatially Dependent Dancoff Method (SDDM) is applied to treat the resonance self-shielding phenomena. It supports concentric sub-ring mesh divisions in a fuel pellet, but still preserves the same level of efficiency as the conventional Stammler method. Modular 2D MOC with two-level Coarse Mesh Finite Difference (CMFD) acceleration is used as the heterogeneous transport solver, which has favorable accuracy and efficiency. Various matrix exponential methods are studied to solve the Bateman burnup equation. The PANDA code is developed on the basis of these methodologies. The numerical results preliminarily demonstrate that the PANDA code has the basic ability for engineering computations.
