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RSS2018 Vol. 30, No. 12
column
- 本期封面及目录
- Research Letter
- High Power Laser and Optics
- ICF and Laser Plasma
- High Power Microwave
- Terahertz Technology
- Complex Electromagnetic Environment
- Particle Beams Technology
- Micro-nano Technology
- Pulsed Power Technology
- Accelerator Technology
- Nuclear Science and Engineering
- Applications of Laserand Particle Beams
Display Method:
2018,
30: 1-2.
2018,
30: 120101.
doi: 10.11884/HPLPB201830.180319
Abstract:
The continuous operation of a W-band gyrotron without superconduct magnet was realized. The gyrotron operated at the second harmonic cyclotron frequency. Its operational frequency was 94.08 GHz and the operating mode was TE02. The required 1.8 T magnetic field was generated by a DC solenoid cooled by water. The power consumption of the solenoid was 28 kW and the driving current was 500 A. The inner bore diameter was 66 mm. The gyrating electron beam was generated by a triode magnetic injection gun. A high efficiency internal quasi-optical mode converter was used to separate the wave from the electron beam. In the test, 5 min stable operation was realized. The output power was 12 kW with an electron beam of 45 kV, 1.7 A. The output efficiency was 15.7%.
The continuous operation of a W-band gyrotron without superconduct magnet was realized. The gyrotron operated at the second harmonic cyclotron frequency. Its operational frequency was 94.08 GHz and the operating mode was TE02. The required 1.8 T magnetic field was generated by a DC solenoid cooled by water. The power consumption of the solenoid was 28 kW and the driving current was 500 A. The inner bore diameter was 66 mm. The gyrating electron beam was generated by a triode magnetic injection gun. A high efficiency internal quasi-optical mode converter was used to separate the wave from the electron beam. In the test, 5 min stable operation was realized. The output power was 12 kW with an electron beam of 45 kV, 1.7 A. The output efficiency was 15.7%.
2018,
30: 121001.
doi: 10.11884/HPLPB201830.180228
Abstract:
Behavior of phase singularities in the distorted optical field is studied by numerical modeling using four-dimension code when a laser beam propagates through uplink and downlink atmospheric turbulence paths. The results reveal that, when the laser beam propagates along an uplink turbulent atmosphere path, the density of phase singularities (DPS) starts at zero and then grows rapidly with the increasing of the propagating height. When the beam propagates to a certain height, the DPS reaches its maximum and then begins to decrease. Such a height changes with the turbulence strength. The stronger the turbulence strength, the bigger the generated DPS, and the lager the maximum DPS with correspondingly lower height. When the laser beam propagates along a downlink turbulent atmosphere path, the stronger turbulence strength is taken, the phase singularities emerge at a higher altitude and the DPS in distorted optical field is bigger near the ground. The functional form of the DPS has a shape of monotone increase with the decrease of the propagation height and the DPS reaches its maximum near the ground. In addition, formulas describing the relationship between the DPS and propagation height/distance are found out. When the laser beam propagates through turbulent atmosphere along an uplink path, the formula is very similar to the formula used for describing the Blackbody radiation in physics. When the laser beam propagates along a downlink atmospheric turbulence path, the DPS seems to be growing exponentially with the propagating distance.
Behavior of phase singularities in the distorted optical field is studied by numerical modeling using four-dimension code when a laser beam propagates through uplink and downlink atmospheric turbulence paths. The results reveal that, when the laser beam propagates along an uplink turbulent atmosphere path, the density of phase singularities (DPS) starts at zero and then grows rapidly with the increasing of the propagating height. When the beam propagates to a certain height, the DPS reaches its maximum and then begins to decrease. Such a height changes with the turbulence strength. The stronger the turbulence strength, the bigger the generated DPS, and the lager the maximum DPS with correspondingly lower height. When the laser beam propagates along a downlink turbulent atmosphere path, the stronger turbulence strength is taken, the phase singularities emerge at a higher altitude and the DPS in distorted optical field is bigger near the ground. The functional form of the DPS has a shape of monotone increase with the decrease of the propagation height and the DPS reaches its maximum near the ground. In addition, formulas describing the relationship between the DPS and propagation height/distance are found out. When the laser beam propagates through turbulent atmosphere along an uplink path, the formula is very similar to the formula used for describing the Blackbody radiation in physics. When the laser beam propagates along a downlink atmospheric turbulence path, the DPS seems to be growing exponentially with the propagating distance.
2018,
30: 121002.
doi: 10.11884/HPLPB201830.180236
Abstract:
For the status quo of traveling wave detector array which can synthesize output power but can't improve work bandwidth, this paper proposes a new L-type array detector. Using a capacitance, a photodiode, and two inductance in series to form a single array unit, the L-type array detector has a cascade cell array structure. The results show that L-type detector can carry on power synthesis of the RF output signal, increaseworking bandwidth to 67 GHz at the same time; Compared with the traditional photoelectric detector, the work bandwidth is tripled. The reasoning method proposed in this paper can be adopted to flexible design of ideal photodiodes, providing a theoretical foundation for future study of photoelectric detectors.
For the status quo of traveling wave detector array which can synthesize output power but can't improve work bandwidth, this paper proposes a new L-type array detector. Using a capacitance, a photodiode, and two inductance in series to form a single array unit, the L-type array detector has a cascade cell array structure. The results show that L-type detector can carry on power synthesis of the RF output signal, increaseworking bandwidth to 67 GHz at the same time; Compared with the traditional photoelectric detector, the work bandwidth is tripled. The reasoning method proposed in this paper can be adopted to flexible design of ideal photodiodes, providing a theoretical foundation for future study of photoelectric detectors.
2018,
30: 121003.
doi: 10.11884/HPLPB201830.180196
Abstract:
In order to reduce the influence of large aperture optical window on the system's incident light and strengthen the performance of optical window and the imaging quality of the optical system, an intermediate zonal auxiliary supporting form (IZASF) based on the ordinary zonal supporting form (OZSF) is proposed in this paper. The influence of these two supporting forms on the wavefront error of optical system was compared under different caliber, thickness ratio and obscuration ratio. Compared with the ordinary zonal supporting form, the intermediate zonal auxiliary supporting form can reduce the wavefront error of the window by 90%. The wavefront error of this window with diameter-thickness ratio 100∶1 and the supporting form IZASF is similar to that of the window with diameter-thickness ratio 100∶3 and the supporting form OZSF. Therefore, the IZASF can effectively improve the supporting efficiency of window and reduce the window thickness and quality. It can also reduce absorbance of the incident light, thus it has great significance to improve the performance and expand the application environment of optical telescopes further.
In order to reduce the influence of large aperture optical window on the system's incident light and strengthen the performance of optical window and the imaging quality of the optical system, an intermediate zonal auxiliary supporting form (IZASF) based on the ordinary zonal supporting form (OZSF) is proposed in this paper. The influence of these two supporting forms on the wavefront error of optical system was compared under different caliber, thickness ratio and obscuration ratio. Compared with the ordinary zonal supporting form, the intermediate zonal auxiliary supporting form can reduce the wavefront error of the window by 90%. The wavefront error of this window with diameter-thickness ratio 100∶1 and the supporting form IZASF is similar to that of the window with diameter-thickness ratio 100∶3 and the supporting form OZSF. Therefore, the IZASF can effectively improve the supporting efficiency of window and reduce the window thickness and quality. It can also reduce absorbance of the incident light, thus it has great significance to improve the performance and expand the application environment of optical telescopes further.
2018,
30: 122001.
doi: 10.11884/HPLPB201830.180174
Abstract:
In order to study the mechanical properties of ion irradiated hollow glass microspheres, the glass sample with the same composition of the hollow glass microspheres was irradiated by Ar ions. Combining with the annealing treatment, the mechanical properties of microsphere glass were studied by means of nanoindentation. The results show that the hardness and modulus of the microsphere glass are decreased after ion irradiation, and the recovery resistance is obviously increased. After annealing, the hardness and modulus of unirradiated samples showed an upward trend, and the recovery resistance did not change within the error range; the hardness of the irradiated microsphere glass is increased, while the modulus and the recovery resistance are significantly decreased. After annealing at around 300 ℃, the recovery resistance of the irradiated sample is the same as the unirradiated sample within the error range.
In order to study the mechanical properties of ion irradiated hollow glass microspheres, the glass sample with the same composition of the hollow glass microspheres was irradiated by Ar ions. Combining with the annealing treatment, the mechanical properties of microsphere glass were studied by means of nanoindentation. The results show that the hardness and modulus of the microsphere glass are decreased after ion irradiation, and the recovery resistance is obviously increased. After annealing, the hardness and modulus of unirradiated samples showed an upward trend, and the recovery resistance did not change within the error range; the hardness of the irradiated microsphere glass is increased, while the modulus and the recovery resistance are significantly decreased. After annealing at around 300 ℃, the recovery resistance of the irradiated sample is the same as the unirradiated sample within the error range.
2018,
30: 122002.
doi: 10.11884/HPLPB201830.180202
Abstract:
Electron beam ion traps(EBITs) play an important role on extreme ultra-violet(EUV) and X-ray spectroscopy in laboratory astrophysics. Residual neutral gas in the EBIT trap center has a significant effect on ion breeding. In this work, we investigated the effect of residual neutral gas on the charge state distribution, as well as the diagnostic for the pressure in the trap center. The charge/energy exchange process between the neutral gas and highly charged ions not only affects the ionic fraction, but also plays an important role in fitting the excitation function (namely the relation curve of ionic fraction as a function of electron energies). By using the ionization equilibrium method on the measured excitation function, we have successfully estimated the residual neutral gas in the ion-electron interaction region of the trap center, as well as the vacuum pressure at the trap center.
Electron beam ion traps(EBITs) play an important role on extreme ultra-violet(EUV) and X-ray spectroscopy in laboratory astrophysics. Residual neutral gas in the EBIT trap center has a significant effect on ion breeding. In this work, we investigated the effect of residual neutral gas on the charge state distribution, as well as the diagnostic for the pressure in the trap center. The charge/energy exchange process between the neutral gas and highly charged ions not only affects the ionic fraction, but also plays an important role in fitting the excitation function (namely the relation curve of ionic fraction as a function of electron energies). By using the ionization equilibrium method on the measured excitation function, we have successfully estimated the residual neutral gas in the ion-electron interaction region of the trap center, as well as the vacuum pressure at the trap center.
2018,
30: 122003.
doi: 10.11884/HPLPB201830.180358
Abstract:
We have proposed a method of non-fixed ring belt random double-side polishing based on the technology of translational pendulum. A device based on translation and pendulum out of limits to fixed ring belt was designed. The iterations were carried out by random motion which solved the periodic trajectory problem in the process of fixed ring belt polishing. We developed a device coupling with double-side polishing based on active translation and pendulum. We have achieved stable control of the large-aperture ultra-thin component surface shape in the random motion superposition by optimizing the combination of movement mode. Compared with planetary double-side polishing, our method not only has better surface shape, but also has no obvious periodic processing trace. The method can be applied to batch production of ultra-thin parts with special requirements for laser damage threshold of surface.
We have proposed a method of non-fixed ring belt random double-side polishing based on the technology of translational pendulum. A device based on translation and pendulum out of limits to fixed ring belt was designed. The iterations were carried out by random motion which solved the periodic trajectory problem in the process of fixed ring belt polishing. We developed a device coupling with double-side polishing based on active translation and pendulum. We have achieved stable control of the large-aperture ultra-thin component surface shape in the random motion superposition by optimizing the combination of movement mode. Compared with planetary double-side polishing, our method not only has better surface shape, but also has no obvious periodic processing trace. The method can be applied to batch production of ultra-thin parts with special requirements for laser damage threshold of surface.
2018,
30: 123001.
doi: 10.11884/HPLPB201830.180201
Abstract:
Based on the ArcPIC code, this paper analyzes the distribution of electron density and the field on the cathode surface using the PIC-MCC method. At the same time, it gives the fitting formula of two-dimensional space charge limited current. This provides a theoretical reference for the design and application of vacuum diodes. It is found that the electric field of cathode surface increases with the increase of cathode current density, then oscillates and tends to a stable state. The two-dimensional space charge limited current density decreases with the increase of cathode emission radius, and the larger the cathode emission radius, the closer the current to the one-dimensional space charge limited current.
Based on the ArcPIC code, this paper analyzes the distribution of electron density and the field on the cathode surface using the PIC-MCC method. At the same time, it gives the fitting formula of two-dimensional space charge limited current. This provides a theoretical reference for the design and application of vacuum diodes. It is found that the electric field of cathode surface increases with the increase of cathode current density, then oscillates and tends to a stable state. The two-dimensional space charge limited current density decreases with the increase of cathode emission radius, and the larger the cathode emission radius, the closer the current to the one-dimensional space charge limited current.
2018,
30: 123002.
doi: 10.11884/HPLPB201830.180139
Abstract:
A radio-frequency (RF) resonant ring test bench has been developed at Peking University for testing and conditioning the power couplers of the 1.3 GHz superconducting radio-frequency accelerator. To maintain the resonant condition of the resonant ring under external disturbance, the Pound-Drever-Hall (PDH) technique has been adopted for frequency locking between the ring and the power source. This paper introduces the application of PDH technique in the RF resonant ring and presents the experiment results showing the effectiveness of the frequency locking against external disturbance.
A radio-frequency (RF) resonant ring test bench has been developed at Peking University for testing and conditioning the power couplers of the 1.3 GHz superconducting radio-frequency accelerator. To maintain the resonant condition of the resonant ring under external disturbance, the Pound-Drever-Hall (PDH) technique has been adopted for frequency locking between the ring and the power source. This paper introduces the application of PDH technique in the RF resonant ring and presents the experiment results showing the effectiveness of the frequency locking against external disturbance.
2018,
30: 123003.
doi: 10.11884/HPLPB201830.180235
Abstract:
A novel compact microstrip low-pass filter with wideband suppression is proposed in this paper. The filter is composed of defect ground structure (DGS) and stepped impedance structure unit. The model was built and optimized by ANSYS HFSS. The simulation results show that the cut-off frequency of the low-pass filter is 1.4 GHz, the passband width is 0-1.4 GHz, the insertion loss in the passband is less than 0.5 dB, the out-of-band rejection frequency width is from 2.1 GHz to 11 GHz, and the out-of-band rejection in the stopband range is about 20 dB. In order to verify the test results and simulation results, an optimized defect-structured microstrip low-pass filter was processed and tested. The practical measurement are in good agreement with the simulation results. It is proved that the defect ground structure plays an important role in realizing the miniaturization of the filter and the wide impedance bandwidth. Moreover, the defect ground structure provides better low-pass filtering characteristics to the filter.
A novel compact microstrip low-pass filter with wideband suppression is proposed in this paper. The filter is composed of defect ground structure (DGS) and stepped impedance structure unit. The model was built and optimized by ANSYS HFSS. The simulation results show that the cut-off frequency of the low-pass filter is 1.4 GHz, the passband width is 0-1.4 GHz, the insertion loss in the passband is less than 0.5 dB, the out-of-band rejection frequency width is from 2.1 GHz to 11 GHz, and the out-of-band rejection in the stopband range is about 20 dB. In order to verify the test results and simulation results, an optimized defect-structured microstrip low-pass filter was processed and tested. The practical measurement are in good agreement with the simulation results. It is proved that the defect ground structure plays an important role in realizing the miniaturization of the filter and the wide impedance bandwidth. Moreover, the defect ground structure provides better low-pass filtering characteristics to the filter.
2018,
30: 123101.
doi: 10.11884/HPLPB201830.180307
Abstract:
Hole-coupling technique is a most common design for high power optically-pumped terahertz gas lasers. In this paper, the intra-cavity modes and beam characteristics of the hole-coupling THz resonators have been numerically calculated with a co-called eigenvector method. Several lowest order modes and their diffraction losses of a series of hole-coupling THz resonators with different g parameters are given. The output beam characteristics from the small hole are studied with the diffraction integral associating with the matrix optical method. The far-field distributions and the divergence angles of each mode are computed.
Hole-coupling technique is a most common design for high power optically-pumped terahertz gas lasers. In this paper, the intra-cavity modes and beam characteristics of the hole-coupling THz resonators have been numerically calculated with a co-called eigenvector method. Several lowest order modes and their diffraction losses of a series of hole-coupling THz resonators with different g parameters are given. The output beam characteristics from the small hole are studied with the diffraction integral associating with the matrix optical method. The far-field distributions and the divergence angles of each mode are computed.
2018,
30: 123201.
doi: 10.11884/HPLPB201830.180238
Abstract:
In order to solve the re-entry blackout problem, based on the former research on magneto window antenna for improving propagation characteristic of electromagnetic wave in plasma sheath, the influence of external electromagnetic control is investigated, the magnet is NdFeB, and the applied voltage is 100 V. Numerical simulation of the flow fields without electromagnetic field, with magnetic field, with electromagnetic field are conducted by using flow field data of different flight altitude. Based on the simulation result, comparison of electronic density and attenuation constant nearby the antenna window with different parameters is shown, and the effects of aircraft flight altitude, the position of electromagnetic window antenna, electromagnetic frequency, the applied voltage electronic density and collision frequency on the electromagnetic window antenna are investigated. The results show that it is feasible to improve electromagnetic propagation in plasma sheath by electromagnetic window antenna, which has better results than magnetic window antenna. With proper working condition of electromagnetic window antenna and appropriate parameters setting, the propagation attenuation would be mitigated obviously by changing the dielectric parameters and the distribution of plasma, thus the phenomena of blackout would be mitigated or eliminated.
In order to solve the re-entry blackout problem, based on the former research on magneto window antenna for improving propagation characteristic of electromagnetic wave in plasma sheath, the influence of external electromagnetic control is investigated, the magnet is NdFeB, and the applied voltage is 100 V. Numerical simulation of the flow fields without electromagnetic field, with magnetic field, with electromagnetic field are conducted by using flow field data of different flight altitude. Based on the simulation result, comparison of electronic density and attenuation constant nearby the antenna window with different parameters is shown, and the effects of aircraft flight altitude, the position of electromagnetic window antenna, electromagnetic frequency, the applied voltage electronic density and collision frequency on the electromagnetic window antenna are investigated. The results show that it is feasible to improve electromagnetic propagation in plasma sheath by electromagnetic window antenna, which has better results than magnetic window antenna. With proper working condition of electromagnetic window antenna and appropriate parameters setting, the propagation attenuation would be mitigated obviously by changing the dielectric parameters and the distribution of plasma, thus the phenomena of blackout would be mitigated or eliminated.
2018,
30: 124001.
doi: 10.11884/HPLPB201830.180216
Abstract:
In this work an anti-scatter grid with higher grid ratio was designed and fabricated based on our previous 2mm grid studies. To clarify the influence of grid thickness and phonon energy on scattering reduction, the acceptance solid angle of a single grid hole was analyzed carefully, where both blocked and unblocked ray were considered. A radiographic experiment and a Monte Carlo simulation were conducted to verify the performance of the grid. Results indicate the contrast of image was nearly doubled when a grid was used. Scatter rejection of the grid was estimated to be at least 1000∶1, which is high enough to suppress most of the scatterings in various application scenes. Results in this work would be helpful in improving the image property of the medium-energy radiography and could be supplied as a valuable reference when designing and fabricating an anti-scatter grid for high-energy flash radiography.
In this work an anti-scatter grid with higher grid ratio was designed and fabricated based on our previous 2mm grid studies. To clarify the influence of grid thickness and phonon energy on scattering reduction, the acceptance solid angle of a single grid hole was analyzed carefully, where both blocked and unblocked ray were considered. A radiographic experiment and a Monte Carlo simulation were conducted to verify the performance of the grid. Results indicate the contrast of image was nearly doubled when a grid was used. Scatter rejection of the grid was estimated to be at least 1000∶1, which is high enough to suppress most of the scatterings in various application scenes. Results in this work would be helpful in improving the image property of the medium-energy radiography and could be supplied as a valuable reference when designing and fabricating an anti-scatter grid for high-energy flash radiography.
2018,
30: 124101.
doi: 10.11884/HPLPB201830.180251
Abstract:
Al, Ni and Al-Ni alloy powders were prepared by the flow-levitation method through electromagnetic induction heating, and the nano-powders were compressed into nanostructured samples by vacuum hot pressure sintering furnace. We used the four-point probe method to measure the values of electrical resistivity (ρ) of the nanostructured aluminum, nickel and Al-Ni alloy samples at temperature (T) ranging from 8 K to 300 K to explore the relationship between the electrical resistivity and temperature. The results show that the resistivity of nanostructured Al, Ni and Al-Ni alloys decreased with the decrease of temperature due to the formation of ordered crystalline phase. The nanostructured Ni3Al-Ni and NiAl-Ni alloys showed a maximum value of resistivity to temperature slope near the Curie temperature, and the Curie temperature of Ni3Al-Ni was 20 K higher than that of coarse-grained Ni3Al because of the influence of nickel elemental. The resistivity of nanosturctured Ni3Al-Ni, NiAl-Ni, and Ni show T2 and T4 law at low temperature (8-40 K) due to magneton-electron scattering and phonon-electron scattering.
Al, Ni and Al-Ni alloy powders were prepared by the flow-levitation method through electromagnetic induction heating, and the nano-powders were compressed into nanostructured samples by vacuum hot pressure sintering furnace. We used the four-point probe method to measure the values of electrical resistivity (ρ) of the nanostructured aluminum, nickel and Al-Ni alloy samples at temperature (T) ranging from 8 K to 300 K to explore the relationship between the electrical resistivity and temperature. The results show that the resistivity of nanostructured Al, Ni and Al-Ni alloys decreased with the decrease of temperature due to the formation of ordered crystalline phase. The nanostructured Ni3Al-Ni and NiAl-Ni alloys showed a maximum value of resistivity to temperature slope near the Curie temperature, and the Curie temperature of Ni3Al-Ni was 20 K higher than that of coarse-grained Ni3Al because of the influence of nickel elemental. The resistivity of nanosturctured Ni3Al-Ni, NiAl-Ni, and Ni show T2 and T4 law at low temperature (8-40 K) due to magneton-electron scattering and phonon-electron scattering.
2018,
30: 125001.
doi: 10.11884/HPLPB201830.180239
Abstract:
The Primary Test Stand (PTS) facility is composed of 24 modules combined in parallel.The load current waveform of the PTS could be shaped by adjusting the closing time of the 24 laser triggered gas switches in each module to perform the magnetically driven experiments.A full circuit model describing the magnetically driven experiments on the PTS facility is proposed.The circuit model includes each elements of the machine from the Marx generator to the load.The load current given by circuit simulation is compared with the experiment result, and they agree with each other very well.The calculation efficiency of the circuit simulation code is much higher than that of Pspice software.The circuit simulation code is not only applicable to evaluating the PTS performance by assuming the closing time of the 24 laser triggered gas switches, but also an effective designing tool for the magnetically driven experiments.
The Primary Test Stand (PTS) facility is composed of 24 modules combined in parallel.The load current waveform of the PTS could be shaped by adjusting the closing time of the 24 laser triggered gas switches in each module to perform the magnetically driven experiments.A full circuit model describing the magnetically driven experiments on the PTS facility is proposed.The circuit model includes each elements of the machine from the Marx generator to the load.The load current given by circuit simulation is compared with the experiment result, and they agree with each other very well.The calculation efficiency of the circuit simulation code is much higher than that of Pspice software.The circuit simulation code is not only applicable to evaluating the PTS performance by assuming the closing time of the 24 laser triggered gas switches, but also an effective designing tool for the magnetically driven experiments.
2018,
30: 125002.
doi: 10.11884/HPLPB201830.170321
Abstract:
This paper analyzes the distribution and correlation of electrical field and magnetic field located at the emission domain in the solenoid for the high power foil less diode using over-mode microwave device based the single electronic moving equations.It is confirmed that the electronic beam transmission efficiency is correlated with the reflux.The results from experimental research indicate that distinct power efficiency was explicated for the emission electronic beam from foil less diode with different radius cathode when the guiding magnetic field inside the magnetic solenoid was bigger.When the beam radius was 48 mm the electronic beam transmission efficiency was more than 95%, when the beam radius was more than 90 mm the efficiency was smaller than 75%.
This paper analyzes the distribution and correlation of electrical field and magnetic field located at the emission domain in the solenoid for the high power foil less diode using over-mode microwave device based the single electronic moving equations.It is confirmed that the electronic beam transmission efficiency is correlated with the reflux.The results from experimental research indicate that distinct power efficiency was explicated for the emission electronic beam from foil less diode with different radius cathode when the guiding magnetic field inside the magnetic solenoid was bigger.When the beam radius was 48 mm the electronic beam transmission efficiency was more than 95%, when the beam radius was more than 90 mm the efficiency was smaller than 75%.
2018,
30: 125003.
doi: 10.11884/HPLPB201830.180190
Abstract:
A self-integrating Rogowski coil is designed and employed to detect the output current of a Marx generator.The Rogowski coil is calibrated with a 1.0kA pulsed power generator which is driven by a capacitor.One TEM chamber is used to obtain the frequency response of the square-wave for the coil.The experiment result can agree with the circuit simulation result very well.The response time of the coil is about 16.0ns.During the experiment the Marx generator output current waveform decays very quickly at the tail of the pulse and the base line is distorted.This is analyzed by the circuit simulation model and the simulation results suggest that the distortion could be eliminated by adjusting the time constant of the RC integrator.The experiment results are consistent with theoretical analysis, and the improved coil can response correctly.
A self-integrating Rogowski coil is designed and employed to detect the output current of a Marx generator.The Rogowski coil is calibrated with a 1.0kA pulsed power generator which is driven by a capacitor.One TEM chamber is used to obtain the frequency response of the square-wave for the coil.The experiment result can agree with the circuit simulation result very well.The response time of the coil is about 16.0ns.During the experiment the Marx generator output current waveform decays very quickly at the tail of the pulse and the base line is distorted.This is analyzed by the circuit simulation model and the simulation results suggest that the distortion could be eliminated by adjusting the time constant of the RC integrator.The experiment results are consistent with theoretical analysis, and the improved coil can response correctly.
2018,
30: 125101.
doi: 10.11884/HPLPB201830.180155
Abstract:
Tuner system is the indispensable part of ADS high current proton superconducting linac.It influences the working frequency of superconducting cavity of particle accelerator.To completely understand the working situation of the tuner system and analyse the problems, experiments were fully conducted.The lever structure and scissor structure of tuner were analyzed first, then the electric field simulations of the HWR superconducting cavity under different conditions were performed, and it was concluded that the force of tuning and tuning displacement meet the frequency tuning requirements of HWR cavity.Finally, the linearity and return difference of the tuner and linear unit in thermostats CM1, CM2, and CM3 were tested automatically and manually.The tuner of CM1 basically meets the need of slow tuning.In the test result of CM2 return of 1200 steps occurred, mainly due to the linear unit.The tuner of CM3 has a large return difference and a little worse linearity that need further improvement.
Tuner system is the indispensable part of ADS high current proton superconducting linac.It influences the working frequency of superconducting cavity of particle accelerator.To completely understand the working situation of the tuner system and analyse the problems, experiments were fully conducted.The lever structure and scissor structure of tuner were analyzed first, then the electric field simulations of the HWR superconducting cavity under different conditions were performed, and it was concluded that the force of tuning and tuning displacement meet the frequency tuning requirements of HWR cavity.Finally, the linearity and return difference of the tuner and linear unit in thermostats CM1, CM2, and CM3 were tested automatically and manually.The tuner of CM1 basically meets the need of slow tuning.In the test result of CM2 return of 1200 steps occurred, mainly due to the linear unit.The tuner of CM3 has a large return difference and a little worse linearity that need further improvement.
2018,
30: 125102.
doi: 10.11884/HPLPB201830.180232
Abstract:
Magnetic field measurement bench is one of the most important facilities to measure magnet and undulator in accelerator domain, and it needs a precise and fast control system to work.Recently, a magnetic field measurement bench was built at Institute of Applied Electronics, China Academy of Engineering Physics.Based on Universal Motion and Automation Controller (UMAC), we designed and developed the control system.The system has a two-level control structure including the upper computer and the lower computer UMAC, which gives full play to their respective advantages: the lower computer can control motor action fast and directly, therefore the programs at the lower machine are responsible for controlling go-stop movement of the 6-axis motion bench; the upper computer has substantial capacity of data processing and storage, therefore the man-machine interface at the upper computer is responsible for collecting, saving and displaying magnetic field data, and it also finishes setting measurement parameters and monitoring work status of magnetic measurement bench.The simultaneity of the two level computer actions is ensured by trigger signals.
Magnetic field measurement bench is one of the most important facilities to measure magnet and undulator in accelerator domain, and it needs a precise and fast control system to work.Recently, a magnetic field measurement bench was built at Institute of Applied Electronics, China Academy of Engineering Physics.Based on Universal Motion and Automation Controller (UMAC), we designed and developed the control system.The system has a two-level control structure including the upper computer and the lower computer UMAC, which gives full play to their respective advantages: the lower computer can control motor action fast and directly, therefore the programs at the lower machine are responsible for controlling go-stop movement of the 6-axis motion bench; the upper computer has substantial capacity of data processing and storage, therefore the man-machine interface at the upper computer is responsible for collecting, saving and displaying magnetic field data, and it also finishes setting measurement parameters and monitoring work status of magnetic measurement bench.The simultaneity of the two level computer actions is ensured by trigger signals.
2018,
30: 125103.
doi: 10.11884/HPLPB201830.180224
Abstract:
Wall current monitors (WCMs) were designed and built for the rapid cycling synchrotron (RCS) of China Spallation Neutron Source (CSNS).The WCMs are used to measure longitudinal bunch shapes in the macro and micro view, calculate longitudinal emittance, and diagnose beam instabilities.The key parameters (e.g., size of the ceramic gap, selection of the resistor and the magnetic materials) of designing a WCM are discussed in this article.The bandwidth of the RCS-WCM can be up to 500 MHz during the lab test, while 30 MHz is required for online operation.The WCM system performed quite well during the beam commissioning and the normal operation of the RCS, beam injection, macro envelope of the accelerating period, and the shape of a single bunch can be observed clearly and accurately.
Wall current monitors (WCMs) were designed and built for the rapid cycling synchrotron (RCS) of China Spallation Neutron Source (CSNS).The WCMs are used to measure longitudinal bunch shapes in the macro and micro view, calculate longitudinal emittance, and diagnose beam instabilities.The key parameters (e.g., size of the ceramic gap, selection of the resistor and the magnetic materials) of designing a WCM are discussed in this article.The bandwidth of the RCS-WCM can be up to 500 MHz during the lab test, while 30 MHz is required for online operation.The WCM system performed quite well during the beam commissioning and the normal operation of the RCS, beam injection, macro envelope of the accelerating period, and the shape of a single bunch can be observed clearly and accurately.
2018,
30: 125104.
doi: 10.11884/HPLPB201830.180191
Abstract:
This paper introduces a high RF power coupling system for ion source application to national large-scale scientific facility CSNS, including the system architecture, RF system metrics calculating, assigning and implementing.This paper focuses on the designs of RF power amplifier, isolation transformer, impedance converter, auxiliary power supply, control & monitor and cooling system.It also discusses the structure and thermal designs in detail and gives the development results of a 80 kW RF power at the least at last based on careful analysis of the characteristic of the RF power coupling system.
This paper introduces a high RF power coupling system for ion source application to national large-scale scientific facility CSNS, including the system architecture, RF system metrics calculating, assigning and implementing.This paper focuses on the designs of RF power amplifier, isolation transformer, impedance converter, auxiliary power supply, control & monitor and cooling system.It also discusses the structure and thermal designs in detail and gives the development results of a 80 kW RF power at the least at last based on careful analysis of the characteristic of the RF power coupling system.
2018,
30: 125105.
doi: 10.11884/HPLPB201830.180286
Abstract:
HEPS (High Energy Photon Source) is a planned ultra-bright and extremely low emittance synchrotron light source which will contain about 2500 magnets.The design of magnet database system includes conceptual and functional design of database, database establishment, web-based management platform design and development.The magnet related data including design, measurements, tests, and operation are typically scattered in various storages which is hard to access for high-level purposes.For such a large number of magnets, it is very important to have essential magnet information systematically stored in relational databases for efficient management and applications.This database is developed with MySQL.To provide a better view and access function of magnet related data, a web-based management platform has been developed for data uploading, querying and managing.This system is of great significance to the installation, operation and maintenance of magnet equipment and the overall equipment information management of HEPS.
HEPS (High Energy Photon Source) is a planned ultra-bright and extremely low emittance synchrotron light source which will contain about 2500 magnets.The design of magnet database system includes conceptual and functional design of database, database establishment, web-based management platform design and development.The magnet related data including design, measurements, tests, and operation are typically scattered in various storages which is hard to access for high-level purposes.For such a large number of magnets, it is very important to have essential magnet information systematically stored in relational databases for efficient management and applications.This database is developed with MySQL.To provide a better view and access function of magnet related data, a web-based management platform has been developed for data uploading, querying and managing.This system is of great significance to the installation, operation and maintenance of magnet equipment and the overall equipment information management of HEPS.
2018,
30: 125106.
doi: 10.11884/HPLPB201830.180205
Abstract:
For long gap tunable undulator systems in free-electron laser (FEL), phase shifters with high control accuracy are required to ensure that the phases of the radiation field between two adjacent undulators matched with each other.We have studied the impact of control accuracy of phase shifter and analyzed its error sources.This study aims to improve the control accuracy of phase shifters and tries to overcome the shortcomings of the traditional calibration methods, such as complicated calibration procedure and low accuracy manual operations.Based on the improved Gaussian-Newton parameter estimation, this paper proposes an automatic error calibration system for phase shifters, including the preliminary concept and the algorithm.This method has been applied to installing and calibrating all the phase shifters of the European X-ray Free Electron (Euro-XFEL).The control accuracy of each phase shifter reaches micrometer-level in the environment of high magnetic forces, which satisfies the specified engineering design requirements.
For long gap tunable undulator systems in free-electron laser (FEL), phase shifters with high control accuracy are required to ensure that the phases of the radiation field between two adjacent undulators matched with each other.We have studied the impact of control accuracy of phase shifter and analyzed its error sources.This study aims to improve the control accuracy of phase shifters and tries to overcome the shortcomings of the traditional calibration methods, such as complicated calibration procedure and low accuracy manual operations.Based on the improved Gaussian-Newton parameter estimation, this paper proposes an automatic error calibration system for phase shifters, including the preliminary concept and the algorithm.This method has been applied to installing and calibrating all the phase shifters of the European X-ray Free Electron (Euro-XFEL).The control accuracy of each phase shifter reaches micrometer-level in the environment of high magnetic forces, which satisfies the specified engineering design requirements.
2018,
30: 126001.
doi: 10.11884/HPLPB201830.180059
Abstract:
The electromagnetic vertical transport scheme based on the solenoid is proposed to transport the falling spherical grains of the spallation target back to their original height after being irradiated by the proton beam, to meet the reliability requirement of the China Accelerator Driven Subcritical System.The mass flow rate of the granular flow and the velocity of the spherical grains at the exit are two critical figures of merit of the granular flow vertical transport device.In this article, such device was investigated and designed based on the analytical method.The drive mode, structure and arrangement of the solenoid suitable for vertically transporting the granular flow are obtained by taking account of heat removal, radial-defocus and axial-focus effects on the granular flow, mutual inductance power loss of the solenoid.An optimized design of the granular flow vertical transport device was obtained based on the simulation results, showing that the granular flow at the mass flow rate of 19.6kg/s could be transported vertically by this device to the height of 40 m, with the velocity of the spherical grain at the exit being large enough.
The electromagnetic vertical transport scheme based on the solenoid is proposed to transport the falling spherical grains of the spallation target back to their original height after being irradiated by the proton beam, to meet the reliability requirement of the China Accelerator Driven Subcritical System.The mass flow rate of the granular flow and the velocity of the spherical grains at the exit are two critical figures of merit of the granular flow vertical transport device.In this article, such device was investigated and designed based on the analytical method.The drive mode, structure and arrangement of the solenoid suitable for vertically transporting the granular flow are obtained by taking account of heat removal, radial-defocus and axial-focus effects on the granular flow, mutual inductance power loss of the solenoid.An optimized design of the granular flow vertical transport device was obtained based on the simulation results, showing that the granular flow at the mass flow rate of 19.6kg/s could be transported vertically by this device to the height of 40 m, with the velocity of the spherical grain at the exit being large enough.
2018,
30: 126002.
doi: 10.11884/HPLPB201830.180218
Abstract:
Efficiency calibration is one of the key problems to be solved in the activity detection of radioactive waste barrels.Based on the assumption of uniform distribution of media material and radionuclides contained in the barrel, Monte Carlo method was used to simulate line attenuation coefficients and body source detection efficiency under various energies and various sample densities.The body source detection efficiency function with linear attenuation coefficient and energy as independent variables is obtained by multivariate nonlinear fitting.And, based on the idea of shell source method, the experiment of the homogenous body source is approximately replaced by multiple point source combination measurement.Three kinds of energy ray and three kinds of density samples have been verified experimentally, and the detection efficiency is calculated respectively by the method of Monte Carlo simulation combining with numerical fitting and the method of experimental measurement.Then, the respective activity estimation results are obtained by solving the efficiency matrix equation, and, the relative error is less than 30%.The simulation results are basically consistent with the experimental result, which proves the effectiveness of the method.
Efficiency calibration is one of the key problems to be solved in the activity detection of radioactive waste barrels.Based on the assumption of uniform distribution of media material and radionuclides contained in the barrel, Monte Carlo method was used to simulate line attenuation coefficients and body source detection efficiency under various energies and various sample densities.The body source detection efficiency function with linear attenuation coefficient and energy as independent variables is obtained by multivariate nonlinear fitting.And, based on the idea of shell source method, the experiment of the homogenous body source is approximately replaced by multiple point source combination measurement.Three kinds of energy ray and three kinds of density samples have been verified experimentally, and the detection efficiency is calculated respectively by the method of Monte Carlo simulation combining with numerical fitting and the method of experimental measurement.Then, the respective activity estimation results are obtained by solving the efficiency matrix equation, and, the relative error is less than 30%.The simulation results are basically consistent with the experimental result, which proves the effectiveness of the method.
2018,
30: 126003.
doi: 10.11884/HPLPB201830.180178
Abstract:
The coarse mesh finite difference method with discontinuity factor correction is one of the effective methods to realize the core transient three-dimensional numerical simulation.The calculation method of coarse mesh interface discontinuity factor and the boundary albedo determines the precision in the process of real-time simulation.In the process of calculation of discontinuity factor and boundary albedo, the fine cell calculation and coarse mesh homogenization process is eliminated.Directly under the condition of the coarse cell, based on the nodal expansion method and nonlinear iterative strategy, coarse cell interface discontinuity factor ratio and boundary albedo are deduced.The corresponding calculation programs are developed.From a typical boiling water reactor 3Dtransient simulation benchmark, the method is proven to be available.The static and transient precisions both in space domain and time domain, are equivalent with that of the advanced nodal method, and the computational efficiency is superior to that of the advanced nodal method.This method provides a feasible choice for the development of full scope simulator of transient calculation of three-dimensional core model.
The coarse mesh finite difference method with discontinuity factor correction is one of the effective methods to realize the core transient three-dimensional numerical simulation.The calculation method of coarse mesh interface discontinuity factor and the boundary albedo determines the precision in the process of real-time simulation.In the process of calculation of discontinuity factor and boundary albedo, the fine cell calculation and coarse mesh homogenization process is eliminated.Directly under the condition of the coarse cell, based on the nodal expansion method and nonlinear iterative strategy, coarse cell interface discontinuity factor ratio and boundary albedo are deduced.The corresponding calculation programs are developed.From a typical boiling water reactor 3Dtransient simulation benchmark, the method is proven to be available.The static and transient precisions both in space domain and time domain, are equivalent with that of the advanced nodal method, and the computational efficiency is superior to that of the advanced nodal method.This method provides a feasible choice for the development of full scope simulator of transient calculation of three-dimensional core model.
2018,
30: 129001.
doi: 10.11884/HPLPB201830.180154
Abstract:
Laser-based approaches for graphene synthesis, reduction, modification, cutting and micro-patterning have been developed and applied to the fabrication of various electronic devices.General method utilized in direct laser writing and patterning of graphene was realized by controlling the movement of the sample or the laser reflecting mirror, while patterning by single shot laser is rarely reported.In the present study, a single shot laser patterning graphene method via light field modulating is proposed.Via controlling the light field by special light modulator (SLM), nanosecond laser pulses focused by objective lens were modulated to the desired pattern.The 4layer graphene in the laser irradiate region was damaged when laser energy was lager than 0.03 mJ.When the laser energy reached 0.06 mJ, clear pattern formed in graphene while no damage occurred in silicon base.The characteristics of graphene patterns were measured using Raman spectra imaging technology.The experimental results revealed that the light field modulated nanosecond laser remains potentially advantageous in graphene micro pattern processing with no need of moving the sample, quick processing and micrometer precision.
Laser-based approaches for graphene synthesis, reduction, modification, cutting and micro-patterning have been developed and applied to the fabrication of various electronic devices.General method utilized in direct laser writing and patterning of graphene was realized by controlling the movement of the sample or the laser reflecting mirror, while patterning by single shot laser is rarely reported.In the present study, a single shot laser patterning graphene method via light field modulating is proposed.Via controlling the light field by special light modulator (SLM), nanosecond laser pulses focused by objective lens were modulated to the desired pattern.The 4layer graphene in the laser irradiate region was damaged when laser energy was lager than 0.03 mJ.When the laser energy reached 0.06 mJ, clear pattern formed in graphene while no damage occurred in silicon base.The characteristics of graphene patterns were measured using Raman spectra imaging technology.The experimental results revealed that the light field modulated nanosecond laser remains potentially advantageous in graphene micro pattern processing with no need of moving the sample, quick processing and micrometer precision.
2018,
30: 129002.
doi: 10.11884/HPLPB201830.180161
Abstract:
To control the light field at the exit end of the photonic crystal waveguide, it is difficult to overcome the radiation of the emitted light from the two-dimensional triangular lattice photonic crystal waveguide.A new type photonic crystal waveguide exit structure was designed using a two-dimensional triangular lattice photonic crystal.Two types of microcavities are introduced at the exit end of a two-dimensional triangular lattice photonic crystal waveguide.Light waves and the microcavity are resonated to form an exit light that is similar to the interference of three point light sources.An exit end bell design is further proposed.Analysis using time-domain finite-difference method shows that the light wave achieves good directional radiation and the radiation distance is significantly improved with the design of the microcavity bell mouth.This kind of photonic crystal device has great significance for the high efficiency coupling with other devices, and has potential application value in photoelectric integration and neardistance optical research.
To control the light field at the exit end of the photonic crystal waveguide, it is difficult to overcome the radiation of the emitted light from the two-dimensional triangular lattice photonic crystal waveguide.A new type photonic crystal waveguide exit structure was designed using a two-dimensional triangular lattice photonic crystal.Two types of microcavities are introduced at the exit end of a two-dimensional triangular lattice photonic crystal waveguide.Light waves and the microcavity are resonated to form an exit light that is similar to the interference of three point light sources.An exit end bell design is further proposed.Analysis using time-domain finite-difference method shows that the light wave achieves good directional radiation and the radiation distance is significantly improved with the design of the microcavity bell mouth.This kind of photonic crystal device has great significance for the high efficiency coupling with other devices, and has potential application value in photoelectric integration and neardistance optical research.
