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RSS2017 Vol. 29, No. 07
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2017,
29: 071001.
doi: 10.11884/HPLPB201729.170021
Abstract:
The characterization of the twist beam can not be accomplished by using only the beam propagation ratios because the transverse cross section keeps changing during propagation. The generation and characterization of the twist Gaussian beam by two cylinder lenses are studied theoretically and experimentally. The twist coefficient is introduced to characterize the level of twist. The beam propagation ratios for the twist Gaussian beam at an azimuth angle are theoretically derived. The twist coefficients of the twist beams generated by two cylinder lenses with different angle and spacing are obtained by using the beam-transfer-matrix and the numerical simulation. The results show that the properties of the twist beam can be characterized better by the combination of the beam propagation ratios and the twist coefficient. The theoretical work is in good agreement with the experimental results.
The characterization of the twist beam can not be accomplished by using only the beam propagation ratios because the transverse cross section keeps changing during propagation. The generation and characterization of the twist Gaussian beam by two cylinder lenses are studied theoretically and experimentally. The twist coefficient is introduced to characterize the level of twist. The beam propagation ratios for the twist Gaussian beam at an azimuth angle are theoretically derived. The twist coefficients of the twist beams generated by two cylinder lenses with different angle and spacing are obtained by using the beam-transfer-matrix and the numerical simulation. The results show that the properties of the twist beam can be characterized better by the combination of the beam propagation ratios and the twist coefficient. The theoretical work is in good agreement with the experimental results.
2017,
29: 071002.
doi: 10.11884/HPLPB201729.160534
Abstract:
Due to the difference between analysis frequency intervals and frequency resolution, and the introduction of window functions, general numerical calculation of power spectral density (PSD) may cause a loss in variance information. With different selection of sampling length and time step, Different amplitudes of PSD are obtained using the calculation. To deal with this problem, PSD is modified in this paper based on the consistence of the variance of the original signal in time domain and integration of PSD in frequency domain. A PSD result that preserves variance information is obtained, so that the PSD analysis can be applied to more general demands, where frequency interval for analysis differs from frequency resolution, and/or highest analysis frequency differs from the reciprocal of time step.
Due to the difference between analysis frequency intervals and frequency resolution, and the introduction of window functions, general numerical calculation of power spectral density (PSD) may cause a loss in variance information. With different selection of sampling length and time step, Different amplitudes of PSD are obtained using the calculation. To deal with this problem, PSD is modified in this paper based on the consistence of the variance of the original signal in time domain and integration of PSD in frequency domain. A PSD result that preserves variance information is obtained, so that the PSD analysis can be applied to more general demands, where frequency interval for analysis differs from frequency resolution, and/or highest analysis frequency differs from the reciprocal of time step.
2017,
29: 071003.
doi: 10.11884/HPLPB201729.160520
Abstract:
To achieve two-dimensional beam shaping, adapt to the parameter variation of divergence angle and beam size, improve beam quality, the article presents a two-dimensional beam shaping method for beams with large aspect ratio and variable divergence angle. Using beam transform matrix to analyze light path, adopting cylindrical lens and spherical lens for two-dimensional beam shaping, and adjusting lens positions and intervals dynamically, the method realizes separate regulation in dimensions x and y of beam size and divergence angle, corrects the lower order aberrations in real time, thus outputs beam of predetermined shape. Experimental study shows that the method has the advantages of simple structure, small comprehensive aberration and large adjustable range.
To achieve two-dimensional beam shaping, adapt to the parameter variation of divergence angle and beam size, improve beam quality, the article presents a two-dimensional beam shaping method for beams with large aspect ratio and variable divergence angle. Using beam transform matrix to analyze light path, adopting cylindrical lens and spherical lens for two-dimensional beam shaping, and adjusting lens positions and intervals dynamically, the method realizes separate regulation in dimensions x and y of beam size and divergence angle, corrects the lower order aberrations in real time, thus outputs beam of predetermined shape. Experimental study shows that the method has the advantages of simple structure, small comprehensive aberration and large adjustable range.
2017,
29: 071004.
doi: 10.11884/HPLPB201729.170030
Abstract:
Based on magnesium oxide-doped periodically poled lithium niobate (MgO:PPLN) crystal, a second-level optical parametric amplifier (OPA) with continuous-wave(CW) laser injection was studied. Pumped by a 10 kHz, 1064 nm, 6 W(the maximum average output power) high-frequency pulse laser and seeded with a low power distributed feedback (DFB) diode CW laser, the OPA obtained a signal at 1652.3 nm and 119 ℃ with the crystal polarization cycle of 31.02 m. The maximum average power of the signal was 125 mW with the quantum conversion efficiency of 7.47%. By changing the wavelength of the seed laser, the output wavelength could be adjusted in the nanometer range. When the signal light passed through the methane gas pool at the distance of 10 m, the spectral intensity decreased obviously, and the feasibility of the signal light in the remote sensing of methane was preliminarily verified. Compared with direct detection by the seed light, the intensity of signal light is much higher, and it has great advantages in detection range and sensitivity.
Based on magnesium oxide-doped periodically poled lithium niobate (MgO:PPLN) crystal, a second-level optical parametric amplifier (OPA) with continuous-wave(CW) laser injection was studied. Pumped by a 10 kHz, 1064 nm, 6 W(the maximum average output power) high-frequency pulse laser and seeded with a low power distributed feedback (DFB) diode CW laser, the OPA obtained a signal at 1652.3 nm and 119 ℃ with the crystal polarization cycle of 31.02 m. The maximum average power of the signal was 125 mW with the quantum conversion efficiency of 7.47%. By changing the wavelength of the seed laser, the output wavelength could be adjusted in the nanometer range. When the signal light passed through the methane gas pool at the distance of 10 m, the spectral intensity decreased obviously, and the feasibility of the signal light in the remote sensing of methane was preliminarily verified. Compared with direct detection by the seed light, the intensity of signal light is much higher, and it has great advantages in detection range and sensitivity.
2017,
29: 071005.
doi: 10.11884/HPLPB201729.160467
Abstract:
Metallic honeycomb sandwich structure is one of the major substructures in the reusable metal thermal projection system (MTPS). The thermal field of metallic honeycomb plate in flows with energy addition was computed. For typical metallic honeycomb kind of TPS, the numerical model of honeycomb core was constructed. The numerical simulation was based on fluid-solid coupling method. Two phase flow model and solidification/melting model were used to simulate the scouring effect. Physical process of laser ablation was described commendably with this method. The results of the thermal field and morphologies are presented in this paper, which indicate that the two phase flow numerical method can well simulate convective heat Transfer, solidification/melting of metallic honeycomb structures and dynamic action of metallic liquid under air flow scouring.
Metallic honeycomb sandwich structure is one of the major substructures in the reusable metal thermal projection system (MTPS). The thermal field of metallic honeycomb plate in flows with energy addition was computed. For typical metallic honeycomb kind of TPS, the numerical model of honeycomb core was constructed. The numerical simulation was based on fluid-solid coupling method. Two phase flow model and solidification/melting model were used to simulate the scouring effect. Physical process of laser ablation was described commendably with this method. The results of the thermal field and morphologies are presented in this paper, which indicate that the two phase flow numerical method can well simulate convective heat Transfer, solidification/melting of metallic honeycomb structures and dynamic action of metallic liquid under air flow scouring.
2017,
29: 071006.
doi: 10.11884/HPLPB201729.170017
Abstract:
The optical properties of metal targets subject to ultrafast laser irradiation are dynamically changing. A hybrid method coupling the two-temperature model with molecular dynamics has been used to simulate the femto-and pico-second laser-induced thermal responses of copper films considering the dynamic and constant optical properties. The constant optical properties include an equivalent average reflectivity calculated by setting equally deposited laser energy and an absorption coefficient at room temperature. The results show that the electron and lattice temperatures are little different in both femtosecond and picosecond laser cases, especially for the femtosecond laser with a pulse width far less than electron-lattice relaxation time. As the laser pulse width is comparable to or greater than the relaxation time, e.g., the picosecond laser, the influence of the dynamic change of the optical properties on the melting and re-solidification of the material becomes more significant.
The optical properties of metal targets subject to ultrafast laser irradiation are dynamically changing. A hybrid method coupling the two-temperature model with molecular dynamics has been used to simulate the femto-and pico-second laser-induced thermal responses of copper films considering the dynamic and constant optical properties. The constant optical properties include an equivalent average reflectivity calculated by setting equally deposited laser energy and an absorption coefficient at room temperature. The results show that the electron and lattice temperatures are little different in both femtosecond and picosecond laser cases, especially for the femtosecond laser with a pulse width far less than electron-lattice relaxation time. As the laser pulse width is comparable to or greater than the relaxation time, e.g., the picosecond laser, the influence of the dynamic change of the optical properties on the melting and re-solidification of the material becomes more significant.
2017,
29: 071007.
doi: 10.11884/HPLPB201729.170006
Abstract:
Previous experiments have shown that high-intensity laser interaction with a solid target can be regarded as a new ionizing radiation source. The radioprotection issue attracts a growing concern worldwide. In order to effectively control the radiological hazard from the X-ray produced by high-intensity laser interaction with solid targets, transmission curves and tenth-value layer (TVL) values in common shielding materials are studied. In this paper, a shielding calculation model was established using Monte Carlo code FLUKA. A specialized routine was developed to solve the problem of repeated scoring caused by the backscattering of particles. Transimitted doses were then obtained for various shielding thicknesses in a single run. The results show that for electron temperatures of 0.5-10 MeV, the TVL value in concrete increases with the electron temperature and ranges from 24 to 56 cm; In lead, except for the first TVL, the equilibrium TVL value shows less correlation with the electron temperature and ranges from 4.7-5.4 cm. In addition, for the high electron temperature, the first TVL value is significantly affected by the distance between the shielding material and the detector.
Previous experiments have shown that high-intensity laser interaction with a solid target can be regarded as a new ionizing radiation source. The radioprotection issue attracts a growing concern worldwide. In order to effectively control the radiological hazard from the X-ray produced by high-intensity laser interaction with solid targets, transmission curves and tenth-value layer (TVL) values in common shielding materials are studied. In this paper, a shielding calculation model was established using Monte Carlo code FLUKA. A specialized routine was developed to solve the problem of repeated scoring caused by the backscattering of particles. Transimitted doses were then obtained for various shielding thicknesses in a single run. The results show that for electron temperatures of 0.5-10 MeV, the TVL value in concrete increases with the electron temperature and ranges from 24 to 56 cm; In lead, except for the first TVL, the equilibrium TVL value shows less correlation with the electron temperature and ranges from 4.7-5.4 cm. In addition, for the high electron temperature, the first TVL value is significantly affected by the distance between the shielding material and the detector.
2017,
29: 072001.
doi: 10.11884/HPLPB201729.170002
Abstract:
Combining PTS facility and magnetized linear inertial fusion (MagLIF) research, 1D simulation code MagLIF-1D was programmed based on MHD theory and DT fuel energy equations. Most challenges came from solving difficulties on boundary coupling, and its convenient to acquire key parameters such as liner velocity, magnetic field strength, fuel density and fusion yield directly from calculated output. Foundational comparisons with LASNEX and HYDRA codes were made to verify the MagLIF-1D code, and differences were discussed and analyzed. The achievements are substantial foundations for further exploring about MagLIF technology, and the calculated results are valuable for future experimental performance.
Combining PTS facility and magnetized linear inertial fusion (MagLIF) research, 1D simulation code MagLIF-1D was programmed based on MHD theory and DT fuel energy equations. Most challenges came from solving difficulties on boundary coupling, and its convenient to acquire key parameters such as liner velocity, magnetic field strength, fuel density and fusion yield directly from calculated output. Foundational comparisons with LASNEX and HYDRA codes were made to verify the MagLIF-1D code, and differences were discussed and analyzed. The achievements are substantial foundations for further exploring about MagLIF technology, and the calculated results are valuable for future experimental performance.
2017,
29: 073201.
doi: 10.11884/HPLPB201729.170027
Abstract:
The applicability of thin slot formalisms(TSFs) in finite-difference time-domain(FDTD) simulation is investigated by comparing the average relative error of different TSFs to fine-gridded FDTD in terms of slot width occupancy and frequency, and by comparing the electric field distribution inside and outside the thin slot. On this basis, the TSFs are employed to predict the shielding effectiveness(SE) of metallic enclosure with thin slot and of an infinite metallic plate with an overlapped rectangular thin slot. Results demonstrate great improvement of computational efficiency caused by applying TSFs in FDTD simulation of structures containing complex thin slot, which are widely used in engineering.
The applicability of thin slot formalisms(TSFs) in finite-difference time-domain(FDTD) simulation is investigated by comparing the average relative error of different TSFs to fine-gridded FDTD in terms of slot width occupancy and frequency, and by comparing the electric field distribution inside and outside the thin slot. On this basis, the TSFs are employed to predict the shielding effectiveness(SE) of metallic enclosure with thin slot and of an infinite metallic plate with an overlapped rectangular thin slot. Results demonstrate great improvement of computational efficiency caused by applying TSFs in FDTD simulation of structures containing complex thin slot, which are widely used in engineering.
2017,
29: 074001.
doi: 10.11884/HPLPB201729.170009
Abstract:
In neutron digital imaging experiments, field programmable gate array (FPGA) is an important logic control unit for imaging. However, neutron irradiation can not only cause single event effects of FPGA, but also bring noises to neutron imaging. It is necessary to take measures to reduce the effects of neutron irradiation on FPGA imaging. In this paper, based on the periodical characteristics of images, a method of two vote from three instead of triplet modular redundancy is adopted to judge imaging key signals. The noises which are caused by many reasons including the single event upset(SEU) in RAM area can be smoothed by using median filter algorithm with hardware implementation. The simulation results show that two techniques and methods used in this paper not only achieve the resource redundancy and cost saving of FPGA, but also get good anti-radiation filtering effect, while preserving image details. Timing simulation and hardware platform have verified the correctness of the design.
In neutron digital imaging experiments, field programmable gate array (FPGA) is an important logic control unit for imaging. However, neutron irradiation can not only cause single event effects of FPGA, but also bring noises to neutron imaging. It is necessary to take measures to reduce the effects of neutron irradiation on FPGA imaging. In this paper, based on the periodical characteristics of images, a method of two vote from three instead of triplet modular redundancy is adopted to judge imaging key signals. The noises which are caused by many reasons including the single event upset(SEU) in RAM area can be smoothed by using median filter algorithm with hardware implementation. The simulation results show that two techniques and methods used in this paper not only achieve the resource redundancy and cost saving of FPGA, but also get good anti-radiation filtering effect, while preserving image details. Timing simulation and hardware platform have verified the correctness of the design.
2017,
29: 074002.
doi: 10.11884/HPLPB201729.160483
Abstract:
Electron beam rapid prototyping machine has high working frequency, trajectory deviation can be caused by many factors, such as iron losses and eddy. We conducted interpolation algorithm to restrain dynamic deviation by getting deflection scanning parameters. However, the way to acquire parameters through optical observation system has relatively low precision. In order to improve the trajectory precision, a parameter acquisition device is installed on the existing electron beam rapid prototyping machine, it can collect secondary reflection electrons and convert them into voltage signal and make it displayed. We can judge the relative position of hole center and electron beam center by the displayed signal. Experiments show that: when the electron beam focuses on the upper surface and its spot locates in the center of the feature point, secondary reflection electron signal is the minimum; meanwhile, the recorded deflection and scanning parameter has high accuracy, therefore the deflection scanning trajectory can be greatly improved.
Electron beam rapid prototyping machine has high working frequency, trajectory deviation can be caused by many factors, such as iron losses and eddy. We conducted interpolation algorithm to restrain dynamic deviation by getting deflection scanning parameters. However, the way to acquire parameters through optical observation system has relatively low precision. In order to improve the trajectory precision, a parameter acquisition device is installed on the existing electron beam rapid prototyping machine, it can collect secondary reflection electrons and convert them into voltage signal and make it displayed. We can judge the relative position of hole center and electron beam center by the displayed signal. Experiments show that: when the electron beam focuses on the upper surface and its spot locates in the center of the feature point, secondary reflection electron signal is the minimum; meanwhile, the recorded deflection and scanning parameter has high accuracy, therefore the deflection scanning trajectory can be greatly improved.
2017,
29: 074101.
doi: 10.11884/HPLPB201729.170007
Abstract:
Thin film bulk acoustic resonators(FBARs) are feasible to detect gamma irradiation by experiments, but the sensing mechanism has not been thoroughly studied. According to two different FBAR structures, two sensing mechanisms are proposed to explain the resonance frequency shift under gamma irradiation. One FBAR structure is four-layer stacked(metal layer-piezoelectric layer-oxide layer-metal layer), after gamma irradiation, it will form a voltage in the radiation sensitive layer(the oxide layer), which is equivalent to impose a DC voltage on the piezoelectric layer, hence the resonant frequency will shift. There is a semiconductor layer between the oxide layer and the piezoelectric layer in the other FBAR structure, and a voltage formed in the oxide layer after irradiation will change the surface potential of the semiconductor and then change the capacitance of the semiconductor space charge layer and finally change the resonant frequency. The results of two different mechanisms are obtained by simulation and compared with the results of the related literature. It is found that the trend of frequency shift and the magnitude of frequency shift are the same, which suggests that the two mechanisms are feasible.
Thin film bulk acoustic resonators(FBARs) are feasible to detect gamma irradiation by experiments, but the sensing mechanism has not been thoroughly studied. According to two different FBAR structures, two sensing mechanisms are proposed to explain the resonance frequency shift under gamma irradiation. One FBAR structure is four-layer stacked(metal layer-piezoelectric layer-oxide layer-metal layer), after gamma irradiation, it will form a voltage in the radiation sensitive layer(the oxide layer), which is equivalent to impose a DC voltage on the piezoelectric layer, hence the resonant frequency will shift. There is a semiconductor layer between the oxide layer and the piezoelectric layer in the other FBAR structure, and a voltage formed in the oxide layer after irradiation will change the surface potential of the semiconductor and then change the capacitance of the semiconductor space charge layer and finally change the resonant frequency. The results of two different mechanisms are obtained by simulation and compared with the results of the related literature. It is found that the trend of frequency shift and the magnitude of frequency shift are the same, which suggests that the two mechanisms are feasible.
2017,
29: 074102.
doi: 10.11884/HPLPB201729.170028
Abstract:
Deep Reactive Ion Etching (DRIE) process on Si to achieve nanopillar arrays with large aspect ratio by using hydrogen silsesquioxane (HSQ) as etching masks has been systematically studied. Parameters in etching process such as coil power, platen power and gas flow have been optimized. The lateral etching has been reduced and the verticality has been controlled better. Under the optimized condition, 13.3 m high Si nanopillars with good verticality, low roughness and the aspect ratio up to 36 (height/FWHM) were fabricated. And Si nanopillars with different sidewall profile, size and height were obtained using different etching conditions.
Deep Reactive Ion Etching (DRIE) process on Si to achieve nanopillar arrays with large aspect ratio by using hydrogen silsesquioxane (HSQ) as etching masks has been systematically studied. Parameters in etching process such as coil power, platen power and gas flow have been optimized. The lateral etching has been reduced and the verticality has been controlled better. Under the optimized condition, 13.3 m high Si nanopillars with good verticality, low roughness and the aspect ratio up to 36 (height/FWHM) were fabricated. And Si nanopillars with different sidewall profile, size and height were obtained using different etching conditions.
2017,
29: 075001.
doi: 10.11884/HPLPB201729.170050
Abstract:
Based on structures in feeder line, two critical factors including resonance and higher mode, which affect bandwidth characteristics of feeder line, are analyzed. By measuring time-domain impedance and S parameters over the range of pulse frequency spectrum, their effect are studied in detail and validated experimentally. The testing results indicate that periodic impedance non-uniformity of feeder line is processed by Fourier transform and can be decomposed into two harmonic components which lead to resonance peaks on voltage standing wave ratio curve. The discontinuous structures in feeder line can excite TE11 and TE21 higher modes which cause loss peaks on transmission loss curve. The －3 dB bandwidth of feeder line is determined by resonance peak that the first harmonic component generates, but it can still match the main lobe width of pulse frequency spectrum. Finally, according to test results, the corresponding improvement measures are put forward to subsequent design optimization of feeder line.
Based on structures in feeder line, two critical factors including resonance and higher mode, which affect bandwidth characteristics of feeder line, are analyzed. By measuring time-domain impedance and S parameters over the range of pulse frequency spectrum, their effect are studied in detail and validated experimentally. The testing results indicate that periodic impedance non-uniformity of feeder line is processed by Fourier transform and can be decomposed into two harmonic components which lead to resonance peaks on voltage standing wave ratio curve. The discontinuous structures in feeder line can excite TE11 and TE21 higher modes which cause loss peaks on transmission loss curve. The －3 dB bandwidth of feeder line is determined by resonance peak that the first harmonic component generates, but it can still match the main lobe width of pulse frequency spectrum. Finally, according to test results, the corresponding improvement measures are put forward to subsequent design optimization of feeder line.
2017,
29: 075002.
doi: 10.11884/HPLPB201729.160445
Abstract:
Firing synchronization is the key for thyristor rectifier control in the EAST polarity field converter power supply system. The converter-transformed second ary voltage signal was adopted as the synchronizing signal to improve the control precision. The state variable filter was used to filter the harmonics and the noise of the synchronizing signal. According to the requirements of the synchronizing signal, the filter design criteria were proposed. The analysis and the parameter calculation of the state variable filter were also made. The real-time simulation and the experiments on the EAST polarity field converter power supply system prove that the designed filter can extract precise synchronization signals.
Firing synchronization is the key for thyristor rectifier control in the EAST polarity field converter power supply system. The converter-transformed second ary voltage signal was adopted as the synchronizing signal to improve the control precision. The state variable filter was used to filter the harmonics and the noise of the synchronizing signal. According to the requirements of the synchronizing signal, the filter design criteria were proposed. The analysis and the parameter calculation of the state variable filter were also made. The real-time simulation and the experiments on the EAST polarity field converter power supply system prove that the designed filter can extract precise synchronization signals.
2017,
29: 075003.
doi: 10.11884/HPLPB201729.170005
Abstract:
The corona discharge effect was employed in the design of the multi-gap gas switch for voltage balance. The performance of the switch was determined by the consistency of the corona current in each gap. Aiming at optimizing the design of the 6-gap switch, corona current in each gap was experimentally investigated at gas pressure from 0.1 to 0.4 MPa. The result shows that corona current in the pin-panel gap is significantly higher than that in the pin-rod gap. 3-D static-electric simulations were carried out, the results of which agree well with that of the experiments. Based on the experiments and simulations, design of the multi-gap gas switch was improved, which achieved a relative standard deviation of corona current in each gap of 8% when charged to 25 kV.
The corona discharge effect was employed in the design of the multi-gap gas switch for voltage balance. The performance of the switch was determined by the consistency of the corona current in each gap. Aiming at optimizing the design of the 6-gap switch, corona current in each gap was experimentally investigated at gas pressure from 0.1 to 0.4 MPa. The result shows that corona current in the pin-panel gap is significantly higher than that in the pin-rod gap. 3-D static-electric simulations were carried out, the results of which agree well with that of the experiments. Based on the experiments and simulations, design of the multi-gap gas switch was improved, which achieved a relative standard deviation of corona current in each gap of 8% when charged to 25 kV.
2017,
29: 075101.
doi: 10.11884/HPLPB201729.160562
Abstract:
In order to improve product reliability, and to quickly identify the source of failure when the electronic equipment breaks down, thus to protect normal operation of the equipment, this paper introduces the diagnosis modeling method based on the multi-signal flow model, and then develops the multi-signal flow fault diagnosis strategy, which is based on the important prior knowledge of the fault, thus improves the technique of multi-signal flow diagnosis by introducing failure probability of the fault mode. The method is then applied to BEPCⅡ magnet power interface control equipment fault diagnosis system by using TEAMS toolbox modeling, which realizes rapid and accurate fault diagnosis and positioning, improves the diagnosis ability of magnet power control equipment, and can be easily extended to other devices and systems.
In order to improve product reliability, and to quickly identify the source of failure when the electronic equipment breaks down, thus to protect normal operation of the equipment, this paper introduces the diagnosis modeling method based on the multi-signal flow model, and then develops the multi-signal flow fault diagnosis strategy, which is based on the important prior knowledge of the fault, thus improves the technique of multi-signal flow diagnosis by introducing failure probability of the fault mode. The method is then applied to BEPCⅡ magnet power interface control equipment fault diagnosis system by using TEAMS toolbox modeling, which realizes rapid and accurate fault diagnosis and positioning, improves the diagnosis ability of magnet power control equipment, and can be easily extended to other devices and systems.
2017,
29: 075102.
doi: 10.11884/HPLPB201729.170019
Abstract:
For the fact that most of the front-end devices are slow devices with communication port in the control system of Linear Induction Accelerator (LIA), this paper combines synchronous communication module Asyn with StreamDevice module to realize the distributed control of these devices based on the EPICS architecture. The multi-parameter input and output methods are proposed based on SCPI and non-SCPI commands. The command format supported by domestic devices is not SCPI, and it is usually needed to read or write multiple PVs in one I/O command, but the protocol in StreamDevice does not support. In this paper, Calcout record is used to combine several PVs in to a structured array to implement setting multiple PVs at one time, and waveform record is used to implement reading multiple PVs at one time.
For the fact that most of the front-end devices are slow devices with communication port in the control system of Linear Induction Accelerator (LIA), this paper combines synchronous communication module Asyn with StreamDevice module to realize the distributed control of these devices based on the EPICS architecture. The multi-parameter input and output methods are proposed based on SCPI and non-SCPI commands. The command format supported by domestic devices is not SCPI, and it is usually needed to read or write multiple PVs in one I/O command, but the protocol in StreamDevice does not support. In this paper, Calcout record is used to combine several PVs in to a structured array to implement setting multiple PVs at one time, and waveform record is used to implement reading multiple PVs at one time.
2017,
29: 075103.
doi: 10.11884/HPLPB201729.170014
Abstract:
A pair of Apple-II type EPU (double elliptical polarization undulators, DEPU) was installed in the SSRF storage ring. The unwanted integral magnetic field errors induced by the devices lead to closed-orbit distortions (COD), tune shifts, coupling variation, reduction of the dynamic aperture and so on. These effects deteriorate the operation performance of the SSRF. Feedforward tables of corrector coils, quadrupoles and skew quadrupoles are used to correct the COD, tune shifts and coupling, respectively. The max COD keeps smaller than 10 m, the tune shifts keep around 0.001 and the coupling keeps 0.1%. Sextupole strengths were optimized to restore the dynamic aperture, the injection efficiency resumes to more than 80%. In the nearly 4 years operation, the compensations have been working well, and there are still more and more supplements and revisions of the feedforward tables in development for the COD corrections.
A pair of Apple-II type EPU (double elliptical polarization undulators, DEPU) was installed in the SSRF storage ring. The unwanted integral magnetic field errors induced by the devices lead to closed-orbit distortions (COD), tune shifts, coupling variation, reduction of the dynamic aperture and so on. These effects deteriorate the operation performance of the SSRF. Feedforward tables of corrector coils, quadrupoles and skew quadrupoles are used to correct the COD, tune shifts and coupling, respectively. The max COD keeps smaller than 10 m, the tune shifts keep around 0.001 and the coupling keeps 0.1%. Sextupole strengths were optimized to restore the dynamic aperture, the injection efficiency resumes to more than 80%. In the nearly 4 years operation, the compensations have been working well, and there are still more and more supplements and revisions of the feedforward tables in development for the COD corrections.
2017,
29: 075104.
doi: 10.11884/HPLPB201729.160489
Abstract:
By observing and analyzing the sparking and breaking down of the high-voltage cable socket of the pulsed power supply during the 72 hours conditioning experiment, the electrical field distribution equivalent circuit of the terminal of the high-voltage cable was built, the formula of the potential difference from the cable-terminal to the metal shielding layer was conducted. The reason of breakdown is analyzed theoretically in this paper. It is suggested that the un-chamfered insulation of the cable-terminal causes space charge focusing, which then results in a temperature increase leading to the high-voltage cable socket breakdown. The theoretical analysis is proved by the position of the breakdown hole of the high-voltage cable socket. The handling method of insulation of the cable terminal is presented, which was validated by continuous conditioning experiment for 72 hours.
By observing and analyzing the sparking and breaking down of the high-voltage cable socket of the pulsed power supply during the 72 hours conditioning experiment, the electrical field distribution equivalent circuit of the terminal of the high-voltage cable was built, the formula of the potential difference from the cable-terminal to the metal shielding layer was conducted. The reason of breakdown is analyzed theoretically in this paper. It is suggested that the un-chamfered insulation of the cable-terminal causes space charge focusing, which then results in a temperature increase leading to the high-voltage cable socket breakdown. The theoretical analysis is proved by the position of the breakdown hole of the high-voltage cable socket. The handling method of insulation of the cable terminal is presented, which was validated by continuous conditioning experiment for 72 hours.
2017,
29: 076001.
doi: 10.11884/HPLPB201729.160320
Abstract:
The linear discontinuous finite element method for the spherical neutron transport equation will give negative angular flux. A positivity preserving linear discontinuous finite element scheme has been constructed and this scheme can preserve zeroth order moment and first order moment of neutron angular flux. A program for the spherical neutron transport problem has been established by the positivity preserving linear discontinuous finite element scheme, which uses the classical scheme by solving linear system of equations when the neutron angular flux is non-negative and adopts the positivity preserving scheme by solving nonlinear system of equations when the neutron angular flux is negative. The numerical results show that the positivity preserving scheme can give non-negative neutron angular flux which reflects the corresponding physical meaning and can give more accurate neutron angular flux and reduce numerical error.
The linear discontinuous finite element method for the spherical neutron transport equation will give negative angular flux. A positivity preserving linear discontinuous finite element scheme has been constructed and this scheme can preserve zeroth order moment and first order moment of neutron angular flux. A program for the spherical neutron transport problem has been established by the positivity preserving linear discontinuous finite element scheme, which uses the classical scheme by solving linear system of equations when the neutron angular flux is non-negative and adopts the positivity preserving scheme by solving nonlinear system of equations when the neutron angular flux is negative. The numerical results show that the positivity preserving scheme can give non-negative neutron angular flux which reflects the corresponding physical meaning and can give more accurate neutron angular flux and reduce numerical error.
2017,
29: 076002.
doi: 10.11884/HPLPB201729.160554
Abstract:
The heat transfer efficiency in high-multiplication water-cooled solid breeder is directly affected by the characteristics of the flow distribution in parallel tubes, however, there are no simple and effective methods for the initial design of the parallel tubes. The characteristics of flow distribution in U-type parallel tubes are simulated by Fluent program, and the sensibilities of geometry parameters and Reynolds number of the tube are analyzed. After that, the key parameters that affect the characteristics of flow distribution are obtained, including the channel length, channel area, number of channels as well as manifolds area. And a method for predicting characteristics of flow distribution is provided. Analysis results show that the lower the dimensionless factor Kfd is, the better the characteristics of flow distribution is. When Kfd is lower than 0.03, the flow loss ratio will be less than 5%.
The heat transfer efficiency in high-multiplication water-cooled solid breeder is directly affected by the characteristics of the flow distribution in parallel tubes, however, there are no simple and effective methods for the initial design of the parallel tubes. The characteristics of flow distribution in U-type parallel tubes are simulated by Fluent program, and the sensibilities of geometry parameters and Reynolds number of the tube are analyzed. After that, the key parameters that affect the characteristics of flow distribution are obtained, including the channel length, channel area, number of channels as well as manifolds area. And a method for predicting characteristics of flow distribution is provided. Analysis results show that the lower the dimensionless factor Kfd is, the better the characteristics of flow distribution is. When Kfd is lower than 0.03, the flow loss ratio will be less than 5%.
