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RSS2017 Vol. 29, No. 06
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2017,
29: 060101.
doi: 10.11884/HPLPB201729.170064
Abstract:
A terahertz wireless communication system is designed. The 16QAM modulation scheme is used in baseband processing, and mixers are used for cascading frequency up and down-converting. Cascading power amplification technique is adopted with a solid-state power amplifier and a vacuum electronic device. Several watts power is emitted at 0.14 THz. An all solid-state receiver running in room temperature is used, whose equivalent noise temperature is 1100 K and receiving sensitivity is -57 dBm. A 21 km wireless communication testing is carried out between the Shuangliu district and the Xinjin county of Chengdu, by means of two Cassegrain antennas with 50 dBi gain each. A 5 Gbps single-channel transmission speed is measured with bit error rate below 10-6. For testing, two standard HD-SDI uncompressed video streams are successfully transmitted in real time simultaneously, with an effective speed of 1.485 Gbps for each one.
A terahertz wireless communication system is designed. The 16QAM modulation scheme is used in baseband processing, and mixers are used for cascading frequency up and down-converting. Cascading power amplification technique is adopted with a solid-state power amplifier and a vacuum electronic device. Several watts power is emitted at 0.14 THz. An all solid-state receiver running in room temperature is used, whose equivalent noise temperature is 1100 K and receiving sensitivity is -57 dBm. A 21 km wireless communication testing is carried out between the Shuangliu district and the Xinjin county of Chengdu, by means of two Cassegrain antennas with 50 dBi gain each. A 5 Gbps single-channel transmission speed is measured with bit error rate below 10-6. For testing, two standard HD-SDI uncompressed video streams are successfully transmitted in real time simultaneously, with an effective speed of 1.485 Gbps for each one.
2017,
29: 061001.
doi: 10.11884/HPLPB201729.160555
Abstract:
The thermal loads of ambient temperature and solar radiation around the telescope directly influence the temperature distribution within the primary mirror for a large-aperture telescope. Based on the unsteady heat conduction and boundary condition in the cylindrical coordinate system, the analytical temperature field for the primary mirror is calculated by separation of variables and Greens function method. To verify the theoretical model, the temperature distribution of a 2.8 m aperture solid mirror is calculated by the analytical solution. The calculated radial temperature distribution at the optical surface is in good agreement with those of FEA method, which reveal that the analytical solution can well reflect temperature distribution at the optical surface. A lightweighted mirror is equivalent to a thin mirror without ribs in the thermal analysis. The FEA analysis is conducted with both the mirror models, which verifies the validity of the equivalent model. The equivalent analytical calculation results of the temperature field for the lightweighted primary mirror have a significant reference value in the early design of the primary mirror for a large-aperture telescope.
The thermal loads of ambient temperature and solar radiation around the telescope directly influence the temperature distribution within the primary mirror for a large-aperture telescope. Based on the unsteady heat conduction and boundary condition in the cylindrical coordinate system, the analytical temperature field for the primary mirror is calculated by separation of variables and Greens function method. To verify the theoretical model, the temperature distribution of a 2.8 m aperture solid mirror is calculated by the analytical solution. The calculated radial temperature distribution at the optical surface is in good agreement with those of FEA method, which reveal that the analytical solution can well reflect temperature distribution at the optical surface. A lightweighted mirror is equivalent to a thin mirror without ribs in the thermal analysis. The FEA analysis is conducted with both the mirror models, which verifies the validity of the equivalent model. The equivalent analytical calculation results of the temperature field for the lightweighted primary mirror have a significant reference value in the early design of the primary mirror for a large-aperture telescope.
2017,
29: 063001.
doi: 10.11884/HPLPB201729.170038
Abstract:
With the increase of output microwave power, the internal field breakdown in a relativistic backward-wave oscillator (RBWO) gets gradually severe. The plasma generated by the field breakdown would lower the attainable output power and pulse width, which greatly limits the single pulse energy. Using a 3-dimensional particle-in-cell (PIC) simulation, the models involving single or several spot breakdown in the reflector, extractor and slow wave structure are built. The plasma effects existing in different locations or having different density are recognized. As demonstrated in the simulation, the output microwave power decreases rapidly as the plasma density increases, breakdown simultaneously occurring at several locations would result in pulse shortening more intensely in contrast to a single spot breakdown, and the easiest plasma effect exists in the breakdown of the reflector.
With the increase of output microwave power, the internal field breakdown in a relativistic backward-wave oscillator (RBWO) gets gradually severe. The plasma generated by the field breakdown would lower the attainable output power and pulse width, which greatly limits the single pulse energy. Using a 3-dimensional particle-in-cell (PIC) simulation, the models involving single or several spot breakdown in the reflector, extractor and slow wave structure are built. The plasma effects existing in different locations or having different density are recognized. As demonstrated in the simulation, the output microwave power decreases rapidly as the plasma density increases, breakdown simultaneously occurring at several locations would result in pulse shortening more intensely in contrast to a single spot breakdown, and the easiest plasma effect exists in the breakdown of the reflector.
2017,
29: 063002.
doi: 10.11884/HPLPB201729.170046
Abstract:
The frequency up-conversion of an electromagnetic wave in a time-varying plasma has been simulated in this paper with particle-in-cell (PIC) method, and it transformed a 2.45 GHz source radiation into a 130 GHz radiation with the power conversion efficiency of around 0.39%. We also studied the effects of the plasma parameters including the plasma density, the finite rise time of ionization and the width of plasma slab. It is concluded that the frequency up-conversion of the output wave was mainly affected by the plasma density, which was consistent with the theoretical results. In addition, the simulation showed that the energy of the output wave would be lager with the increase of the width of plasma slab, and the conversion efficiency of the output wave and spectrum were much better when the plasma rise time was shorter. A considerable 130 GHz radiation could be obtained with the plasma density of 21020 cm-3, the plasma thickness of 1 cm, and the plasma rise time of 0.04 ns.
The frequency up-conversion of an electromagnetic wave in a time-varying plasma has been simulated in this paper with particle-in-cell (PIC) method, and it transformed a 2.45 GHz source radiation into a 130 GHz radiation with the power conversion efficiency of around 0.39%. We also studied the effects of the plasma parameters including the plasma density, the finite rise time of ionization and the width of plasma slab. It is concluded that the frequency up-conversion of the output wave was mainly affected by the plasma density, which was consistent with the theoretical results. In addition, the simulation showed that the energy of the output wave would be lager with the increase of the width of plasma slab, and the conversion efficiency of the output wave and spectrum were much better when the plasma rise time was shorter. A considerable 130 GHz radiation could be obtained with the plasma density of 21020 cm-3, the plasma thickness of 1 cm, and the plasma rise time of 0.04 ns.
2017,
29: 065001.
doi: 10.11884/HPLPB201729.160480
Abstract:
This paper present the numerical analytical solutions for the plane wave reflection coefficient in isotropic, constant velocity medium nonuniform impedance transmission lines (with exponential, hyperbolic and linear impedance profiles). The energy efficiencies are quantified as function of v (vis the ratio of the pulse width to the one-way transit time of the transformers) and Q(Q is the ratio of the output impedance to the input impedance of the transformers).The analytical results indicate the exponential transformers have the maximum energy efficiencies when the frequency is low. Finally the energy efficiencies of Z300 are calculated, the energy efficiencies of the transmission lines with exponential, hyperbolic and linear impedance profiles are 91.%, 90.4%, 91.2% respectively.
This paper present the numerical analytical solutions for the plane wave reflection coefficient in isotropic, constant velocity medium nonuniform impedance transmission lines (with exponential, hyperbolic and linear impedance profiles). The energy efficiencies are quantified as function of v (vis the ratio of the pulse width to the one-way transit time of the transformers) and Q(Q is the ratio of the output impedance to the input impedance of the transformers).The analytical results indicate the exponential transformers have the maximum energy efficiencies when the frequency is low. Finally the energy efficiencies of Z300 are calculated, the energy efficiencies of the transmission lines with exponential, hyperbolic and linear impedance profiles are 91.%, 90.4%, 91.2% respectively.
2017,
29: 065002.
doi: 10.11884/HPLPB201729.170004
Abstract:
A novel diode was designed to produce large-area X-ray and the electrons utilized were mainly from the upstream conical Magnetically Insulated Transmission Line (MITL). The diode is characterized by the use of large angle incident electrons to produce bremsstrahlung radiation. The diode was simulated and analyzed by a combination of two-dimensional Particle-In-Cell (PIC) and MCNP 4C software, and a uniform X-ray area could be found at the downstream of the diode. This paper presents a new idea on how to set the MCNP source better to reflect the angular uniformity. The relationship between three important parameters of the diode and the electrons transportation character are studied. The results show a uniform X-ray field could be obtained using this diode without additional electron transport control structure.
A novel diode was designed to produce large-area X-ray and the electrons utilized were mainly from the upstream conical Magnetically Insulated Transmission Line (MITL). The diode is characterized by the use of large angle incident electrons to produce bremsstrahlung radiation. The diode was simulated and analyzed by a combination of two-dimensional Particle-In-Cell (PIC) and MCNP 4C software, and a uniform X-ray area could be found at the downstream of the diode. This paper presents a new idea on how to set the MCNP source better to reflect the angular uniformity. The relationship between three important parameters of the diode and the electrons transportation character are studied. The results show a uniform X-ray field could be obtained using this diode without additional electron transport control structure.
2017,
29: 065003.
doi: 10.11884/HPLPB201729.170037
Abstract:
This paper presents experimental study of the electrical and optical characteristics of the pulsed plasma jet enhanced radio-frequency(RF) atmospheric glow discharge. The combined electrode system was employed in the experiments by introducing pulse power electrode in the front of the radio frequency power electrode, and the plasma jet was injected into the RF discharge region in the form of plasma bullets. The waveforms of voltage and current,the minimum maintaining voltage of RF discharge, the spatio-temporal evolution of discharge spatial profile are studied. It is found that the discharge intensity of the radio frequency discharge is enhanced spatio-temporally by the introduction of plasma species with plasma bullet,and the minimum sustaining voltage of the RF discharge is reduced from 0.93 kV to 0.43 kV.
This paper presents experimental study of the electrical and optical characteristics of the pulsed plasma jet enhanced radio-frequency(RF) atmospheric glow discharge. The combined electrode system was employed in the experiments by introducing pulse power electrode in the front of the radio frequency power electrode, and the plasma jet was injected into the RF discharge region in the form of plasma bullets. The waveforms of voltage and current,the minimum maintaining voltage of RF discharge, the spatio-temporal evolution of discharge spatial profile are studied. It is found that the discharge intensity of the radio frequency discharge is enhanced spatio-temporally by the introduction of plasma species with plasma bullet,and the minimum sustaining voltage of the RF discharge is reduced from 0.93 kV to 0.43 kV.
2017,
29: 065004.
doi: 10.11884/HPLPB201729.160468
Abstract:
The power supply of the pulse xenon lamp is a key device in high-speed photography test system. Based on the analysis for the parameters of the pulse xenon lamp with a length of 540mm, a diameter of 18mm and a gap of 250mm, a pulsed xenon lamp power supply developed with manual trigger and external trigger functions, xenon lamp charging voltage 2.5～4.5 kV and output pulse current amplitude 3～6 kA with the pulse width of 230 s. Experimental results are given in the case of single trigger. The power supply system adopts the phase shift control of the thyristor to control the voltage regulator module and charges the capacitor linearly. IGBT power semiconductor switching device generates a pulse signal, and the set-up transformer amplifies the signal to trigger the xenon lamp, then the xenon lamp is turned on to emit light. With control signal isolation and capacitor grounded at the end, the method suppresses the effective artificial ground potential, improves the reliability of power supply and anti-electromagnetic interference ability. Hundreds of experiments show the power supply triggers the pulsed xenon lamp with 100% reliability.
The power supply of the pulse xenon lamp is a key device in high-speed photography test system. Based on the analysis for the parameters of the pulse xenon lamp with a length of 540mm, a diameter of 18mm and a gap of 250mm, a pulsed xenon lamp power supply developed with manual trigger and external trigger functions, xenon lamp charging voltage 2.5～4.5 kV and output pulse current amplitude 3～6 kA with the pulse width of 230 s. Experimental results are given in the case of single trigger. The power supply system adopts the phase shift control of the thyristor to control the voltage regulator module and charges the capacitor linearly. IGBT power semiconductor switching device generates a pulse signal, and the set-up transformer amplifies the signal to trigger the xenon lamp, then the xenon lamp is turned on to emit light. With control signal isolation and capacitor grounded at the end, the method suppresses the effective artificial ground potential, improves the reliability of power supply and anti-electromagnetic interference ability. Hundreds of experiments show the power supply triggers the pulsed xenon lamp with 100% reliability.
2017,
29: 065005.
doi: 10.11884/HPLPB201729.160472
Abstract:
For the requirements of thermodynamic effect research, a high magnetic field system was designed. The high magnetic field system is consisted of four components: capacitor bank, semiconducting output switch, magnetic coil and high voltage power supply. The designed max magnetic field is 5 T and the magnetic lens ratio could be adjusted by changing the distance between magnetic coil and diode. Key parameters of the magnetic field are investigated by theoretical analysis and numerical simulation. Based on the theoretical analysis and numerical results, a high magnetic field generator has been manufactured. The experiments with the generator show that when the capacitor bank is charged to 20 kV, the max magnetic induction intensity at the coil center is 5.3 T.
For the requirements of thermodynamic effect research, a high magnetic field system was designed. The high magnetic field system is consisted of four components: capacitor bank, semiconducting output switch, magnetic coil and high voltage power supply. The designed max magnetic field is 5 T and the magnetic lens ratio could be adjusted by changing the distance between magnetic coil and diode. Key parameters of the magnetic field are investigated by theoretical analysis and numerical simulation. Based on the theoretical analysis and numerical results, a high magnetic field generator has been manufactured. The experiments with the generator show that when the capacitor bank is charged to 20 kV, the max magnetic induction intensity at the coil center is 5.3 T.
2017,
29: 065006.
doi: 10.11884/HPLPB201729.170029
Abstract:
The exposure at 1 m just in front of the target is an important parameter for evaluating the radiation ability of the accelerator light source. The X-ray photons produced by the electron beam striking a high-Z target show a distinct forward angular distribution, so the spatial distribution of the exposure is closely related to the beam emittance. The Gauss model is applied to simulate the positional distribution and the directional distribution of the incident electrons interacting with the convertor target for various beam emittances. The bremsstrahlung radiation process that the electron beam impinges on the target is simulated utilizing the Monte Carlo method, by which the influence of the beam emittance on the exposure is analyzed. The exposure of the bremsstrahlung light source using the multi-foil target is also calculated and compared with the one using the standard slab target. The results indicate that the divergence angle of the electron beam is the main factor that affects the exposure of the bremsstrahlung radiation. Compared with using the slab target, the spatial distribution of the exposure obtained by using the multi-foil target is basically the same except that the exposure decreases by 2%-3% within a small angular range of 0-4.
The exposure at 1 m just in front of the target is an important parameter for evaluating the radiation ability of the accelerator light source. The X-ray photons produced by the electron beam striking a high-Z target show a distinct forward angular distribution, so the spatial distribution of the exposure is closely related to the beam emittance. The Gauss model is applied to simulate the positional distribution and the directional distribution of the incident electrons interacting with the convertor target for various beam emittances. The bremsstrahlung radiation process that the electron beam impinges on the target is simulated utilizing the Monte Carlo method, by which the influence of the beam emittance on the exposure is analyzed. The exposure of the bremsstrahlung light source using the multi-foil target is also calculated and compared with the one using the standard slab target. The results indicate that the divergence angle of the electron beam is the main factor that affects the exposure of the bremsstrahlung radiation. Compared with using the slab target, the spatial distribution of the exposure obtained by using the multi-foil target is basically the same except that the exposure decreases by 2%-3% within a small angular range of 0-4.
2017,
29: 065007.
doi: 10.11884/HPLPB201729.170049
Abstract:
In order to study the aerodynamics of the airfoil based on plasma circulation control, the Reynolds average N-S equation and mathematics model of plasma excitation based on phenomenology method are used, and the change characteristics of lift affected by the trailing radius are simulated, the optimum radius is determined. Through the low speed wind, the experiment is conducted at the angle of attack of -4 to 12, and at the speed of 6 m/s, 10 m/s, 15 m/s. The pressure distribution and lift coefficient are obtained. The results of the simulation and experiment show: it is unfavorable for the formation of Coanda effect with too large trailing radius or too small trailing radius, and the optimum ratio of radius and wing chord is 0.048, with the efficiency-cost ratio up to 97.69. The laminar separation of long bubble and short bubble appears with the increase of the angle of attack at low Reynolds number. The influences of plasma jet not only include the tail flow field, but also include improving laminar separation based on the increased circulation, and increasing the lift.
In order to study the aerodynamics of the airfoil based on plasma circulation control, the Reynolds average N-S equation and mathematics model of plasma excitation based on phenomenology method are used, and the change characteristics of lift affected by the trailing radius are simulated, the optimum radius is determined. Through the low speed wind, the experiment is conducted at the angle of attack of -4 to 12, and at the speed of 6 m/s, 10 m/s, 15 m/s. The pressure distribution and lift coefficient are obtained. The results of the simulation and experiment show: it is unfavorable for the formation of Coanda effect with too large trailing radius or too small trailing radius, and the optimum ratio of radius and wing chord is 0.048, with the efficiency-cost ratio up to 97.69. The laminar separation of long bubble and short bubble appears with the increase of the angle of attack at low Reynolds number. The influences of plasma jet not only include the tail flow field, but also include improving laminar separation based on the increased circulation, and increasing the lift.
2017,
29: 065008.
doi: 10.11884/HPLPB201729.170048
Abstract:
In order to overcome the disadvantages of using the conventional mechanical methods to explore marine Co-rich crust, such as crushing head wearing easily, low efficiency and high dilution ratio, we developed a new technology using experimental investigation, in which the pulse power techniques were used to explore the marine Co-rich crust. A power source was designed using solid-state Marx circuits together with semiconductor switch IGBT, which could generate negative high voltage pulses with rising edge 100 ns and maximum amplitude 40 kV. The breaking way adopted needle-needle electrodes which contact the same surface of rocks closely. To improve the potential of areas where the needles contact with the surface of rocks, stainless pins were used as the electrodes. Results indicate that plasma channels were generated and sandstones were broken when the amplitude of high voltage pulse was 32.5 kV and the distance between electrodes was 3 mm. Moreover, discharges happen either during the rising-time or after the rising-time of high voltage pulses. The changing curves of voltage and current show the plasma channels have variable impedance during discharge processes.
In order to overcome the disadvantages of using the conventional mechanical methods to explore marine Co-rich crust, such as crushing head wearing easily, low efficiency and high dilution ratio, we developed a new technology using experimental investigation, in which the pulse power techniques were used to explore the marine Co-rich crust. A power source was designed using solid-state Marx circuits together with semiconductor switch IGBT, which could generate negative high voltage pulses with rising edge 100 ns and maximum amplitude 40 kV. The breaking way adopted needle-needle electrodes which contact the same surface of rocks closely. To improve the potential of areas where the needles contact with the surface of rocks, stainless pins were used as the electrodes. Results indicate that plasma channels were generated and sandstones were broken when the amplitude of high voltage pulse was 32.5 kV and the distance between electrodes was 3 mm. Moreover, discharges happen either during the rising-time or after the rising-time of high voltage pulses. The changing curves of voltage and current show the plasma channels have variable impedance during discharge processes.
2017,
29: 065009.
doi: 10.11884/HPLPB201729.160448
Abstract:
The design of the primary system for International Thermo-nuclear Experimental Reactor(ITER) Pulsed Power Electrical Network(PPEN) is introduced. Technical requirements and type selections are described including transformer, circuit breaker, disconnecting switch, instrument transformer, surge arrester, busbar of 400 kV/66 kV/22 kV class. Simulation analysis for PPEN system, which demonstrates that the primary system of PPEN can meet the requirements of ITER operation is done. Finally the progress and work plan for ITER PPEN in china is represented.
The design of the primary system for International Thermo-nuclear Experimental Reactor(ITER) Pulsed Power Electrical Network(PPEN) is introduced. Technical requirements and type selections are described including transformer, circuit breaker, disconnecting switch, instrument transformer, surge arrester, busbar of 400 kV/66 kV/22 kV class. Simulation analysis for PPEN system, which demonstrates that the primary system of PPEN can meet the requirements of ITER operation is done. Finally the progress and work plan for ITER PPEN in china is represented.
2017,
29: 065010.
doi: 10.11884/HPLPB201729.160452
Abstract:
This paper introduces the integrated protection system of EAST neutron beam injection (NBI) high voltage power supply. From three aspects of protection (main circuits protection, power modules protection and site safety monitoring), it presents the basic principle of the system, describes the hardware and software of site safety monitors, and realizes the design of PC monitoring software using LabVIEW. The system provides effective security for the EAST-NBI high voltage power supply, which produces spark frequently and has a high security risk, and it is of great significance to the safety of personnel and equipment in EAST experiment.
This paper introduces the integrated protection system of EAST neutron beam injection (NBI) high voltage power supply. From three aspects of protection (main circuits protection, power modules protection and site safety monitoring), it presents the basic principle of the system, describes the hardware and software of site safety monitors, and realizes the design of PC monitoring software using LabVIEW. The system provides effective security for the EAST-NBI high voltage power supply, which produces spark frequently and has a high security risk, and it is of great significance to the safety of personnel and equipment in EAST experiment.
2017,
29: 065101.
doi: 10.11884/HPLPB201729.160502
Abstract:
A multi-pulse X-ray radiography system, based on an RF linear accelerator, was suggested to be employed in diagnosis for hydrodynamic test. The system can provide several interval-adjustable electron pulses, with pulse widths of tens to a hundred nanoseconds and beam transverse size (FWHM) less than 1 mm, within a duration of 10 s. We used Monte Carlo codes, Geant4, to simulate bremsstrahlung characteristics, such as exposure dose, energy deposit in target and increment of X-ray spot size by electron scatter, of 30 MeV electron beams bombarding tantalum target with various thickness in a certain radiography layout. Simulation results show that the exposure dose at 1 m away from the target right ahead was about 9.1 R and the X-ray spot sizes were not increased obviously with the thickness increment. The pulse number was limited by temperature rise in target, which was increased intensely with a very tiny beam transverse size. The rotating target could be employed to break the limitation of pulse number, but the pulse interval was limited by decrement of yield strength with the rise of target temperature.
A multi-pulse X-ray radiography system, based on an RF linear accelerator, was suggested to be employed in diagnosis for hydrodynamic test. The system can provide several interval-adjustable electron pulses, with pulse widths of tens to a hundred nanoseconds and beam transverse size (FWHM) less than 1 mm, within a duration of 10 s. We used Monte Carlo codes, Geant4, to simulate bremsstrahlung characteristics, such as exposure dose, energy deposit in target and increment of X-ray spot size by electron scatter, of 30 MeV electron beams bombarding tantalum target with various thickness in a certain radiography layout. Simulation results show that the exposure dose at 1 m away from the target right ahead was about 9.1 R and the X-ray spot sizes were not increased obviously with the thickness increment. The pulse number was limited by temperature rise in target, which was increased intensely with a very tiny beam transverse size. The rotating target could be employed to break the limitation of pulse number, but the pulse interval was limited by decrement of yield strength with the rise of target temperature.
2017,
29: 065102.
doi: 10.11884/HPLPB201729.160530
Abstract:
Large grain niobium has good thermal conductivity at 2 K temperature because of the phonon peak, which is helpful to improve the thermal stability of superconducting cavities. The investigation into thermal conductivity and crystal imperfection of the large grain niobium material developed by Ningxia Orient Tantalum Industry Co., Ltd (OTIC) with different heat treatments has been carried out. Results show the phonon peak of OTIC large grain niobium can be recovered by heat treatment at a temperature of more than 800 ℃, which is different from previous measurements at DESY. In this paper we present the experiments, results and discussion of thermal conductivity investigation of OTIC large grain niobium.
Large grain niobium has good thermal conductivity at 2 K temperature because of the phonon peak, which is helpful to improve the thermal stability of superconducting cavities. The investigation into thermal conductivity and crystal imperfection of the large grain niobium material developed by Ningxia Orient Tantalum Industry Co., Ltd (OTIC) with different heat treatments has been carried out. Results show the phonon peak of OTIC large grain niobium can be recovered by heat treatment at a temperature of more than 800 ℃, which is different from previous measurements at DESY. In this paper we present the experiments, results and discussion of thermal conductivity investigation of OTIC large grain niobium.
2017,
29: 065103.
doi: 10.11884/HPLPB201729.160547
Abstract:
Electron accelerators adjust electromagnetic field to guide the electron beam to travel along an ideal orbit, requiring reliable excitation power supply with high precision, high reliability, small ripple and strong anti-interference ability. This paper introduces the structure, controller system and control algorithm of NSRL-HLS low power DC magnet power supply, as well as some relative simulation and experiment research. The measured current ripple is 2.12, the current stability is 6.6 and the current resolution is 0.01 under the load inductance 1.0 mH, equivalent series resistance 0.049 and output current 25 A. It is proved that the designed main circuit and controller system are suitable for the experimental research of low power DC magnet power supply.
Electron accelerators adjust electromagnetic field to guide the electron beam to travel along an ideal orbit, requiring reliable excitation power supply with high precision, high reliability, small ripple and strong anti-interference ability. This paper introduces the structure, controller system and control algorithm of NSRL-HLS low power DC magnet power supply, as well as some relative simulation and experiment research. The measured current ripple is 2.12, the current stability is 6.6 and the current resolution is 0.01 under the load inductance 1.0 mH, equivalent series resistance 0.049 and output current 25 A. It is proved that the designed main circuit and controller system are suitable for the experimental research of low power DC magnet power supply.
2017,
29: 065104.
doi: 10.11884/HPLPB201729.160529
Abstract:
The resonant perturbation method can only be applied for the measurement of the standing wave RF field, while the non-resonant perturbation method works for both the standing wave and the traveling wave RF fields. In the hybrid buncher, both the standing wave and the travelling wave RF fields exist. In this scenario, only the non-resonant perturbation method can be adopted. A set of electromagnetic field distribution measurement platform was developed and used for the field distribution measurement and tuning of the hybrid buncher. After several iterations, the measured RF performance of the hybrid buncher was in good agreement with the simulated result.
The resonant perturbation method can only be applied for the measurement of the standing wave RF field, while the non-resonant perturbation method works for both the standing wave and the traveling wave RF fields. In the hybrid buncher, both the standing wave and the travelling wave RF fields exist. In this scenario, only the non-resonant perturbation method can be adopted. A set of electromagnetic field distribution measurement platform was developed and used for the field distribution measurement and tuning of the hybrid buncher. After several iterations, the measured RF performance of the hybrid buncher was in good agreement with the simulated result.
2017,
29: 066002.
doi: 10.11884/HPLPB201729.160561
Abstract:
The segmented gamma-scanning (SGS) measurement is a non-destructive analysis technology. It is an important method of qualitative and quantitative analyse for nuclear waste drums. However, the HPGe detectors detection efficiency is related with the location of the radionuclide in the actual measuring process, so it is necessary to do efficiency calibration for different locations. This paper presents the study based on SGS measurement method. The waste drum was filled with uniform polyethylene samples. The radionuclides were approximated as point sources. Seven points were selected in each of the three uniform segments of the drum for efficiency calibration. Shell-source method and geometrical factor method were used to calculate the weighted detection efficiency for calibration of each point. The results show that this method can estimate the nuclide activity at different positions in the drum quickly and accurately with acceptable errors.
The segmented gamma-scanning (SGS) measurement is a non-destructive analysis technology. It is an important method of qualitative and quantitative analyse for nuclear waste drums. However, the HPGe detectors detection efficiency is related with the location of the radionuclide in the actual measuring process, so it is necessary to do efficiency calibration for different locations. This paper presents the study based on SGS measurement method. The waste drum was filled with uniform polyethylene samples. The radionuclides were approximated as point sources. Seven points were selected in each of the three uniform segments of the drum for efficiency calibration. Shell-source method and geometrical factor method were used to calculate the weighted detection efficiency for calibration of each point. The results show that this method can estimate the nuclide activity at different positions in the drum quickly and accurately with acceptable errors.
2017,
29: 065107.
doi: 10.11884/HPLPB201729.160545
Abstract:
The RF system is a key part of the high intensity RFQ (Radio Frequency Quadrupole) accelerator in the project of Chinese Accelerator Driven System (C-ADS), which provides and transfers power for a quadrilateral four-vane resonator with two coupling ports. A special scheme was considered for accelerating 10 mA proton beam since the beginning of RFQ design. In this paper, the strategy for RF system, which is very important for demand of CW (continuous wave) operating mode, is considered; performance of the elements including an RF amplifier, couplers and a transmission system will be calculated and analyzed carefully to ensure they can operate reliably and safely. A test with 10 mA CW proton beam was carried out in 2015 to verify the design and configuration. Specially, a new kind of coupler with bowl-shaped ceramic window and a novel tuning method without circulator during beam commissioning are presented in detail, and the specific two-port configuration is deduced for accelerator operation firstly.
The RF system is a key part of the high intensity RFQ (Radio Frequency Quadrupole) accelerator in the project of Chinese Accelerator Driven System (C-ADS), which provides and transfers power for a quadrilateral four-vane resonator with two coupling ports. A special scheme was considered for accelerating 10 mA proton beam since the beginning of RFQ design. In this paper, the strategy for RF system, which is very important for demand of CW (continuous wave) operating mode, is considered; performance of the elements including an RF amplifier, couplers and a transmission system will be calculated and analyzed carefully to ensure they can operate reliably and safely. A test with 10 mA CW proton beam was carried out in 2015 to verify the design and configuration. Specially, a new kind of coupler with bowl-shaped ceramic window and a novel tuning method without circulator during beam commissioning are presented in detail, and the specific two-port configuration is deduced for accelerator operation firstly.
2017,
29: 066001.
doi: 10.11884/HPLPB201729.160256
Abstract:
Resonance calculation must treat global and local effects, namely, the interference among different pins, the interference among different nuclides, nuclide distribution effect and temperature distribution effect. The conventional resonance method cant exactly solve all the problems, simultaneously. This paper uses pseudo isotope method to treat the interference effect among different nuclides with high precise and efficiency. According to the assessment of the generalized equivalence theory, a high-fidelity resonance calculation method is proposed. In order to incorporate the global effect, the iteration calculation is performed for the U-238 based heterogeneous table. After the background cross sections for different fuel pin are obtained, the interpolation of the table is carried out to find an equivalent pin. Then the ultra-fine calculation is carried out on the equivalence pin based on the real nuclide composition and temperature distribution to get the high-fidelity effective cross sections for the nuclide at different position in the fuel pin.
Resonance calculation must treat global and local effects, namely, the interference among different pins, the interference among different nuclides, nuclide distribution effect and temperature distribution effect. The conventional resonance method cant exactly solve all the problems, simultaneously. This paper uses pseudo isotope method to treat the interference effect among different nuclides with high precise and efficiency. According to the assessment of the generalized equivalence theory, a high-fidelity resonance calculation method is proposed. In order to incorporate the global effect, the iteration calculation is performed for the U-238 based heterogeneous table. After the background cross sections for different fuel pin are obtained, the interpolation of the table is carried out to find an equivalent pin. Then the ultra-fine calculation is carried out on the equivalence pin based on the real nuclide composition and temperature distribution to get the high-fidelity effective cross sections for the nuclide at different position in the fuel pin.
2017,
29: 065106.
doi: 10.11884/HPLPB201729.160412
Abstract:
Sub-sampling technology has been adopted to realize fully-digitalized beam phase measurement electronics system for linac in China Spallation Neutron Source(CSNS). This paper introduces measurement principle and operation procedure of the system and describes analog signal processing, sampling and frequency module. It also presents the experimental results of measuring 324 MHz/100 mVpp sine wave, which achieves phase resolution less than 0.1 and non-uniformity between channels limited in 0.2, satisfying the requirements of system.
Sub-sampling technology has been adopted to realize fully-digitalized beam phase measurement electronics system for linac in China Spallation Neutron Source(CSNS). This paper introduces measurement principle and operation procedure of the system and describes analog signal processing, sampling and frequency module. It also presents the experimental results of measuring 324 MHz/100 mVpp sine wave, which achieves phase resolution less than 0.1 and non-uniformity between channels limited in 0.2, satisfying the requirements of system.
2017,
29: 066003.
doi: 10.11884/HPLPB201729.160279
Abstract:
Space-time neutronics simulation code has been widely applied to accidents analysis of pressurized water reactor power plant and technical service projects such as dynamic rod worth measurement. This paper gives a brief introduction to the progress of the self-dependent developed code CORCA-K. The CORCA-K space-time neutronics simulation code is a part of the code package NESTOR developed by CNPE. The main task of this code is to solve the three dimensional transient neutron diffusion equations with numerical methods. The spatial discretization is done by the Nodal Greens Function method with Neumann boundary condition, to keep consistency with the three dimensional static code CORCA-3D. The temporal discretization is done by the Diagonally Implicit Runge-Kutta method, which can be easily achieved on the basis of backward Euler method, and provides the code the function of automatic time step optimization. The code is verified by the three dimensional LMW/LRA benchmarks and dynamic calculation of unit 3 cycle 5 of Qinshan NPP. The verification shows that the results calculated by CORCA-K agree well with those calculated by referential codes. In addition, the code is more efficient while achieving the same accuracy level.
Space-time neutronics simulation code has been widely applied to accidents analysis of pressurized water reactor power plant and technical service projects such as dynamic rod worth measurement. This paper gives a brief introduction to the progress of the self-dependent developed code CORCA-K. The CORCA-K space-time neutronics simulation code is a part of the code package NESTOR developed by CNPE. The main task of this code is to solve the three dimensional transient neutron diffusion equations with numerical methods. The spatial discretization is done by the Nodal Greens Function method with Neumann boundary condition, to keep consistency with the three dimensional static code CORCA-3D. The temporal discretization is done by the Diagonally Implicit Runge-Kutta method, which can be easily achieved on the basis of backward Euler method, and provides the code the function of automatic time step optimization. The code is verified by the three dimensional LMW/LRA benchmarks and dynamic calculation of unit 3 cycle 5 of Qinshan NPP. The verification shows that the results calculated by CORCA-K agree well with those calculated by referential codes. In addition, the code is more efficient while achieving the same accuracy level.
2017,
29: 066004.
doi: 10.11884/HPLPB201729.160470
Abstract:
In the measurement of radiation source boundary using radiation imaging system, time diffusion of scintillant affects the measurement result. We constructed a type of radiation source having different intensity time width, boundary diffusion speed and relative intensity, then computed the deviation betweens boundary real size with the sizes in cases of scintillants BC408, LaBr3 and LSO respectively, by means of convolution and image intensity gradient. The results show that while photography time is 20 ns, deviation will be the smallest with the scintillant BC408; since a scintillator is not suitable for the measurement when deviation is greater than 1mm, the minimum values of intensity time width should be 266 ns, 133 ns and 33 ns for scintillants LSO, LaBr3 and BC408, respectively; however, the deviation doesnt vary with scintillant materials in complete integral imaging. Finally, a formula is summed up for deviation computation, which can well reflect the trend of real deviation.
In the measurement of radiation source boundary using radiation imaging system, time diffusion of scintillant affects the measurement result. We constructed a type of radiation source having different intensity time width, boundary diffusion speed and relative intensity, then computed the deviation betweens boundary real size with the sizes in cases of scintillants BC408, LaBr3 and LSO respectively, by means of convolution and image intensity gradient. The results show that while photography time is 20 ns, deviation will be the smallest with the scintillant BC408; since a scintillator is not suitable for the measurement when deviation is greater than 1mm, the minimum values of intensity time width should be 266 ns, 133 ns and 33 ns for scintillants LSO, LaBr3 and BC408, respectively; however, the deviation doesnt vary with scintillant materials in complete integral imaging. Finally, a formula is summed up for deviation computation, which can well reflect the trend of real deviation.
2017,
29: 065105.
doi: 10.11884/HPLPB201729.160491
Abstract:
RF power coupler is one of the key components in China Spallation Neutron Source (CSNS) Drift Tube Linac (DTL), its coupling coefficient is usually obtained by changing the dimensions of coupling hole mechanically. In order to make sure that the coupling coefficient reaches the designed value, a cold model is manufactured for the coupling coefficient adjustments. During the measurement of the cold model, it is found that the coupling coefficient cannot reach the target value by changing the hole diameter only. Therefore, a new simulation model with good accuracy in comparison with measurement results is proposed for analysis, and the theory used in Proton Engineering Frontier Project (PEFP) and the main parameters affecting the coupling coefficient are analyzed accordingly. Finally, the coupling coefficient is adjusted to the target value, and the low power test results of copper model show a good agreement with the simulation results.
RF power coupler is one of the key components in China Spallation Neutron Source (CSNS) Drift Tube Linac (DTL), its coupling coefficient is usually obtained by changing the dimensions of coupling hole mechanically. In order to make sure that the coupling coefficient reaches the designed value, a cold model is manufactured for the coupling coefficient adjustments. During the measurement of the cold model, it is found that the coupling coefficient cannot reach the target value by changing the hole diameter only. Therefore, a new simulation model with good accuracy in comparison with measurement results is proposed for analysis, and the theory used in Proton Engineering Frontier Project (PEFP) and the main parameters affecting the coupling coefficient are analyzed accordingly. Finally, the coupling coefficient is adjusted to the target value, and the low power test results of copper model show a good agreement with the simulation results.
