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RSS2019 Vol. 31, No. 3
Recommend Articles
2019, 31: 035001.
doi: 10.11884/HPLPB201931.190005
2019, 31: 036003.
doi: 10.11884/HPLPB201931.180283
Display Method:
2019,
31: 1-2.
2019,
31: 032001.
doi: 10.11884/HPLPB201931.190045
Abstract:
Optical properties of wide-angle velocity interferometer system for any reflector (VISAR) are studied in this paper. The principle of wide-angle VISAR is expounded. It reveals that the role of the ellipsoid in wide-angle VISAR is to make the inner surface of capsule into a curved virtual image at the center of target. The effect of imaging bending on the formation of dynamic interference fringes is simulated by Zemax and a shaped optical fiber plate is proposed for image correction. The influence of assembly error is also studied. To obtain a good imaging result, the positional deviation of the ellipsoidal mirror should not exceed 30 μm, the inclination should not exceed 4°, the manufacturing error requires less than 0.1 μm in long axis direction and 4 μm in short axis direction, and reflectance needs to be higher than 70%. More possible factors of affecting dynamic fringes, other methods of imaging correction, correspondence between object and image are discussed, along with the potential development of wide-angle VISAR. The optical properties of wide-angle VISAR is a basis for improving the wide-angle diagnostic capability, and is of great significance for the quantitative observation for driving symmetry of capsule in inertial confinement fusion.
Optical properties of wide-angle velocity interferometer system for any reflector (VISAR) are studied in this paper. The principle of wide-angle VISAR is expounded. It reveals that the role of the ellipsoid in wide-angle VISAR is to make the inner surface of capsule into a curved virtual image at the center of target. The effect of imaging bending on the formation of dynamic interference fringes is simulated by Zemax and a shaped optical fiber plate is proposed for image correction. The influence of assembly error is also studied. To obtain a good imaging result, the positional deviation of the ellipsoidal mirror should not exceed 30 μm, the inclination should not exceed 4°, the manufacturing error requires less than 0.1 μm in long axis direction and 4 μm in short axis direction, and reflectance needs to be higher than 70%. More possible factors of affecting dynamic fringes, other methods of imaging correction, correspondence between object and image are discussed, along with the potential development of wide-angle VISAR. The optical properties of wide-angle VISAR is a basis for improving the wide-angle diagnostic capability, and is of great significance for the quantitative observation for driving symmetry of capsule in inertial confinement fusion.
2019,
31: 032002.
doi: 10.11884/HPLPB201931.180329
Abstract:
Aiming at the discharge characteristics of radio frequency capacitively coupled (CCRF) plasma at moderate pressure and medium power, a one-dimensional plasma discharge model was established by using COMSOL software based on fluid model. The distribution law in plasma electron temperature and electron density were studied at the same pressure and different radio frequency input power with Ar gas as working gas. At the same time, a closed glass cavity and a flat plate electrode of the same size were designed and fabricated according to the simulation model. The effective current, voltage and emission spectrum of the discharge plasma were measured experimentally at different RF input power. The electron temperature and electron density of the plasma were calculated by the current-voltage relationship and the energy balance equation. The electron temperature and electron density of plasma were obtained by Boltzmann double-wire method. When the gas pressure was 250 Pa and the input power was 100-450 W, the plasma voltage and current showed a linear relationship. The electron density increased with the increase of the power, but the electron temperature did not change with the change of the power. At the same time, the accuracy of the experiment was further verified by simulation. In this paper, the discharge parameters of plasma at moderate pressure are preliminarily diagnosed by combining the equivalent circuit method, spectral method and numerical simulation method, and a combination of these three methods is proposed for experiment to make the experimental results more convincing and to provide a basis for further study of plasma characteristics.
Aiming at the discharge characteristics of radio frequency capacitively coupled (CCRF) plasma at moderate pressure and medium power, a one-dimensional plasma discharge model was established by using COMSOL software based on fluid model. The distribution law in plasma electron temperature and electron density were studied at the same pressure and different radio frequency input power with Ar gas as working gas. At the same time, a closed glass cavity and a flat plate electrode of the same size were designed and fabricated according to the simulation model. The effective current, voltage and emission spectrum of the discharge plasma were measured experimentally at different RF input power. The electron temperature and electron density of the plasma were calculated by the current-voltage relationship and the energy balance equation. The electron temperature and electron density of plasma were obtained by Boltzmann double-wire method. When the gas pressure was 250 Pa and the input power was 100-450 W, the plasma voltage and current showed a linear relationship. The electron density increased with the increase of the power, but the electron temperature did not change with the change of the power. At the same time, the accuracy of the experiment was further verified by simulation. In this paper, the discharge parameters of plasma at moderate pressure are preliminarily diagnosed by combining the equivalent circuit method, spectral method and numerical simulation method, and a combination of these three methods is proposed for experiment to make the experimental results more convincing and to provide a basis for further study of plasma characteristics.
Operating characteristics of an S-band relativistic backward wave oscillator with low magnetic field
2019,
31: 033001.
doi: 10.11884/HPLPB201931.190010
Abstract:
In order to reduce the volume and weight of the high power microwave (HPM) system, an S-band relativistic backward wave oscillator(RBWO) operating at low guiding magnetic field is designed. The operation magnetic field of the RBWO is lower than that of the electron cyclotron resonance, which will decrease the electron beam transmission efficiency and beam-wave interaction impedance. By increasing the distance between the electron beam and the inner wall of the device, the transmission efficiency of the electron beam can be improved. The deep slow-wave structure is used as extraction cavity to enhance the efficiency of beam-wave interaction. The shallow slow-wave structure in front of extraction cavity is adopted to ensure synchronization of electron velocity and microwave phase velocity. The high power microwave is acquired under low guiding magnetic field. Simulation shows that 670 MW output power with 25% efficiency is generated under a guiding magnetic field of 0.17 T, electron voltage of 435 kV and beam current of 6.5 kA. Compared to the conventional magnetic field system (B of 0.8 T), the radius of solenoid of the 0.17 T low magnetic field system applied to the RBWO is reduced by 20%, and the energy consumption is reduced by about 93.2%.
In order to reduce the volume and weight of the high power microwave (HPM) system, an S-band relativistic backward wave oscillator(RBWO) operating at low guiding magnetic field is designed. The operation magnetic field of the RBWO is lower than that of the electron cyclotron resonance, which will decrease the electron beam transmission efficiency and beam-wave interaction impedance. By increasing the distance between the electron beam and the inner wall of the device, the transmission efficiency of the electron beam can be improved. The deep slow-wave structure is used as extraction cavity to enhance the efficiency of beam-wave interaction. The shallow slow-wave structure in front of extraction cavity is adopted to ensure synchronization of electron velocity and microwave phase velocity. The high power microwave is acquired under low guiding magnetic field. Simulation shows that 670 MW output power with 25% efficiency is generated under a guiding magnetic field of 0.17 T, electron voltage of 435 kV and beam current of 6.5 kA. Compared to the conventional magnetic field system (B of 0.8 T), the radius of solenoid of the 0.17 T low magnetic field system applied to the RBWO is reduced by 20%, and the energy consumption is reduced by about 93.2%.
2019,
31: 033002.
doi: 10.11884/HPLPB201931.180342
Abstract:
In this paper, an X~Ku band broadband 1 W driver amplifier MMIC based on 0.25 μm GaN HEMT on SiC process is designed. The design uses an equivalent RC model of active devices' large-signal output impedance for verifying the accuracy of the GaN HEMT process model. And large-signal output impedances of GaN HEMT with different dimensions are achieved. Negative feedback structure is applied for the first-stage transistor to reduce the Q value of the matching network. The broadband matching is successfully achieved through band-pass matching network topology. The measurement results show that this driver amplifier at 28 V operation voltage achieved over 30 dBm output power, 21% power added efficiency and 15 dB power gain from 8 GHz to 18 GHz. The chip size is 2.20 mm×1.45 mm. The MMIC chip has the characteristics of wide bandwidth, high efficiency and small size. It can be mainly used in fields such as millimeter-wave transceiver components and wireless communication, and has broad application prospect.
In this paper, an X~Ku band broadband 1 W driver amplifier MMIC based on 0.25 μm GaN HEMT on SiC process is designed. The design uses an equivalent RC model of active devices' large-signal output impedance for verifying the accuracy of the GaN HEMT process model. And large-signal output impedances of GaN HEMT with different dimensions are achieved. Negative feedback structure is applied for the first-stage transistor to reduce the Q value of the matching network. The broadband matching is successfully achieved through band-pass matching network topology. The measurement results show that this driver amplifier at 28 V operation voltage achieved over 30 dBm output power, 21% power added efficiency and 15 dB power gain from 8 GHz to 18 GHz. The chip size is 2.20 mm×1.45 mm. The MMIC chip has the characteristics of wide bandwidth, high efficiency and small size. It can be mainly used in fields such as millimeter-wave transceiver components and wireless communication, and has broad application prospect.
2019,
31: 033201.
doi: 10.11884/HPLPB201931.190011
Abstract:
It is important to obtain the coupling section(CS) of aperture for analyzing aperture penetration/leakage of electromagnetic wave. However, there are no ready-made formulas for calculating CS of circular apertures in the resonance region. Therefore, a backpropagation(BP) neural network is applied to the fast acquisition of CS of circular apertures with electrical dimensions (ratio of radius and wavelength) of [0.08, 3]. Full-wave analysis software is used to calculate the CSs of circular apertures with different electrical dimensions on an infinitely large, perfectly conducting plate illuminated by plane-waves at different incident angles and polarization angles. By dividing the CS by the geometric area of the aperture, the normalized CS is obtained. And then, the full-wave analysis data are used as training data for a BP neural network model, including aperture electrical dimension, incident angle and polarization angle as input and normalized CS as output. Test results suggest that this model can quickly and accurately predict the normalized CSs of circular aperture with electrical dimensions [0.08, 3] under a plane-wave illumination at any incident angle and polarization angle.
It is important to obtain the coupling section(CS) of aperture for analyzing aperture penetration/leakage of electromagnetic wave. However, there are no ready-made formulas for calculating CS of circular apertures in the resonance region. Therefore, a backpropagation(BP) neural network is applied to the fast acquisition of CS of circular apertures with electrical dimensions (ratio of radius and wavelength) of [0.08, 3]. Full-wave analysis software is used to calculate the CSs of circular apertures with different electrical dimensions on an infinitely large, perfectly conducting plate illuminated by plane-waves at different incident angles and polarization angles. By dividing the CS by the geometric area of the aperture, the normalized CS is obtained. And then, the full-wave analysis data are used as training data for a BP neural network model, including aperture electrical dimension, incident angle and polarization angle as input and normalized CS as output. Test results suggest that this model can quickly and accurately predict the normalized CSs of circular aperture with electrical dimensions [0.08, 3] under a plane-wave illumination at any incident angle and polarization angle.
2019,
31: 034101.
doi: 10.11884/HPLPB201931.180375
Abstract:
In order to effectively characterize the RF noise characteristics in the strong inversion region of nanoscale MOSFET, the noise modeling method is studied. Based on the analysis of extracted results of radio frequency small-signal equivalent circuit parameters of 45 nm MOSFET, a compact model for the MOSFET's drain current noise is proposed. This model fully describes three kinds of main physical sources that determine the noise mechanism of 45 nm MOSFET, including intrinsic drain current noise, thermal noise induced by the gate parasitic resistance, and coupling thermal noise induced by substrate parasitic effect. The accuracy of the proposed model is verified by noise measurements, and the intrinsic drain current noise of 45 nm MOSFET is proved to be the suppressed shot noise, and with the decrease of the gate voltage, the suppressed degree gradually decreases until it vanishes.
In order to effectively characterize the RF noise characteristics in the strong inversion region of nanoscale MOSFET, the noise modeling method is studied. Based on the analysis of extracted results of radio frequency small-signal equivalent circuit parameters of 45 nm MOSFET, a compact model for the MOSFET's drain current noise is proposed. This model fully describes three kinds of main physical sources that determine the noise mechanism of 45 nm MOSFET, including intrinsic drain current noise, thermal noise induced by the gate parasitic resistance, and coupling thermal noise induced by substrate parasitic effect. The accuracy of the proposed model is verified by noise measurements, and the intrinsic drain current noise of 45 nm MOSFET is proved to be the suppressed shot noise, and with the decrease of the gate voltage, the suppressed degree gradually decreases until it vanishes.
2019,
31: 035001.
doi: 10.11884/HPLPB201931.190005
Abstract:
In this paper, an all-solid-state high-frequency and high-voltage pulse generator is designed. The main circuit uses a half-bridge solid-state Marx circuit with IGBTs as main switches. The drive circuit uses a magnetic-isolated synchronous driver with negative voltage bias. Charge and discharge control signals and fault diagnosis and protection operation are processed by an FPGA. The capacitors in different stages can be charged quickly in parallel through low-impedance loops, and meanwhile the slow tailing pulses are truncated to generate square pulses. Besides, the pulse width over 200 μs are achieved due to the hold-on of the gate-emitter capacitors, which can be used to generate high-voltage pulsed electric field. In addition, this pulse generator can also output various numbers of high-frequency pulses with adjustable pulse numbers in burst mode. Experiments show that pulses with the output voltage amplitude of 40 kV, the peak current of 100 A, the repetitive frequency of 30 kHz, the rise time and the fall time less than 100ns are obtained. The burst mode frequency can be up to 200 kHz. The designed pulse generator is able to output high-voltage pulses with continuously adjustable parameters and the generator's size is very small.
In this paper, an all-solid-state high-frequency and high-voltage pulse generator is designed. The main circuit uses a half-bridge solid-state Marx circuit with IGBTs as main switches. The drive circuit uses a magnetic-isolated synchronous driver with negative voltage bias. Charge and discharge control signals and fault diagnosis and protection operation are processed by an FPGA. The capacitors in different stages can be charged quickly in parallel through low-impedance loops, and meanwhile the slow tailing pulses are truncated to generate square pulses. Besides, the pulse width over 200 μs are achieved due to the hold-on of the gate-emitter capacitors, which can be used to generate high-voltage pulsed electric field. In addition, this pulse generator can also output various numbers of high-frequency pulses with adjustable pulse numbers in burst mode. Experiments show that pulses with the output voltage amplitude of 40 kV, the peak current of 100 A, the repetitive frequency of 30 kHz, the rise time and the fall time less than 100ns are obtained. The burst mode frequency can be up to 200 kHz. The designed pulse generator is able to output high-voltage pulses with continuously adjustable parameters and the generator's size is very small.
2019,
31: 035002.
doi: 10.11884/HPLPB201931.180320
Abstract:
The detection of the load current signal is one of the effective methods for judging whether an arc fault occurs in the low-voltage distribution line; according to the national standard GB/T 31143-2014 "General Requirements for Arc Fault Protection Devices (AFDD)", the analog series fault arc is built. The experimental platform studies the characteristics of the current waveform when the fault arc occurs. The db4 wavelet function is used as the wavelet basis function to decompose and reconstruct the current waveform after noise reduction, and extract the wavelet high-frequency component, calculate the periodic variance value of the wavelet high-frequency component, and detect the arc fault according to this value; The feasibility and effectiveness of the detection algorithm are verified. The arc fault detection algorithm is transplanted to the STM32 platform, and the fault arc detection device based on STM32 is designed. The device can realize the functions of current signal acquisition, data processing and series arc fault detection and recognition. Experiments with resistive loads, LED light, vacuum cleaners and microwave ovens have shown that the device can detect series arc faults with high reliability and will not cause false positives without generating fault arcs.
The detection of the load current signal is one of the effective methods for judging whether an arc fault occurs in the low-voltage distribution line; according to the national standard GB/T 31143-2014 "General Requirements for Arc Fault Protection Devices (AFDD)", the analog series fault arc is built. The experimental platform studies the characteristics of the current waveform when the fault arc occurs. The db4 wavelet function is used as the wavelet basis function to decompose and reconstruct the current waveform after noise reduction, and extract the wavelet high-frequency component, calculate the periodic variance value of the wavelet high-frequency component, and detect the arc fault according to this value; The feasibility and effectiveness of the detection algorithm are verified. The arc fault detection algorithm is transplanted to the STM32 platform, and the fault arc detection device based on STM32 is designed. The device can realize the functions of current signal acquisition, data processing and series arc fault detection and recognition. Experiments with resistive loads, LED light, vacuum cleaners and microwave ovens have shown that the device can detect series arc faults with high reliability and will not cause false positives without generating fault arcs.
2019,
31: 035003.
doi: 10.11884/HPLPB201931.180317
Abstract:
The launching of the railgun needs enough amplitude and width trapezoid wave current. This article presents three working modes of two inductive pulsed power supplies supplying one load. The load current magnification and the pulse width increment are different under these three different working modes. Simulation and experiment results show: the load current magnification is the largest and the pulse width increment is the smallest when two STRETCH meat grinder modules work at the same mode; the load current magnification is the smallest and the pulse width increment is the largest when the main switches of two STRETCH meat grinder modules open simultaneously and the thyristor of the second model delays the first one; the load current magnification and the pulse width increment is medium when the second model delays the first model. From the results we can get the right current by choosing the appropriate triggering.
The launching of the railgun needs enough amplitude and width trapezoid wave current. This article presents three working modes of two inductive pulsed power supplies supplying one load. The load current magnification and the pulse width increment are different under these three different working modes. Simulation and experiment results show: the load current magnification is the largest and the pulse width increment is the smallest when two STRETCH meat grinder modules work at the same mode; the load current magnification is the smallest and the pulse width increment is the largest when the main switches of two STRETCH meat grinder modules open simultaneously and the thyristor of the second model delays the first one; the load current magnification and the pulse width increment is medium when the second model delays the first model. From the results we can get the right current by choosing the appropriate triggering.
2019,
31: 035004.
doi: 10.11884/HPLPB201931.180315
Abstract:
International thermonuclear experimental reactor (ITER) poloidal field (PF) converter is a high-power and heavy-current six-pulse converter bridge with rated capacity of 41 MV·A and rated current of 27.5 kA. For such a large rated current, ITER PF converter is designed to consist of 12 thyristor branches in parallel on each bridge arm. In temperature rise test, the temperature of several key parts such as thyristor case, fast fuse, flexible connection and RC loop resistance in the thyristor branch needs to be detected. If the temperature measurement points are arranged in each thyristor branch, there will be hundreds of temperature measurement points, which greatly increases the difficulty of temperature rise test. In order to decrease the temperature measurement points and facilitate the temperature rise test, the test method that the current balance test is performed first to get three thyristor branches with maximum current sharing and then the temperature rise test is performed at that key parts on these three thyristor branches is proposed in this paper. According to Joule's law, the key parts temperature rise of other thyristor branches must satisfy the requirement as long as the temperature rise of that key parts in these three thyristor branches with maximum current sharing satisfies the requirement. This test method simplifies the temperature measurement points from hundreds to dozens, which facilitates the layout of temperature measurement points and the acquisition of temperature data.
International thermonuclear experimental reactor (ITER) poloidal field (PF) converter is a high-power and heavy-current six-pulse converter bridge with rated capacity of 41 MV·A and rated current of 27.5 kA. For such a large rated current, ITER PF converter is designed to consist of 12 thyristor branches in parallel on each bridge arm. In temperature rise test, the temperature of several key parts such as thyristor case, fast fuse, flexible connection and RC loop resistance in the thyristor branch needs to be detected. If the temperature measurement points are arranged in each thyristor branch, there will be hundreds of temperature measurement points, which greatly increases the difficulty of temperature rise test. In order to decrease the temperature measurement points and facilitate the temperature rise test, the test method that the current balance test is performed first to get three thyristor branches with maximum current sharing and then the temperature rise test is performed at that key parts on these three thyristor branches is proposed in this paper. According to Joule's law, the key parts temperature rise of other thyristor branches must satisfy the requirement as long as the temperature rise of that key parts in these three thyristor branches with maximum current sharing satisfies the requirement. This test method simplifies the temperature measurement points from hundreds to dozens, which facilitates the layout of temperature measurement points and the acquisition of temperature data.
2019,
31: 035005.
doi: 10.11884/HPLPB201931.180288
Abstract:
The characteristics of high-voltage power supplies have a significant impact on the performance of the scintillation neutron detector. In order to overcome the problem of large volume and poor portability of traditional high-voltage power supply equipment, we used the internal integrated miniaturized high-voltage module to provide high-voltage for PMT in the development of portable pulsed neutron detector. According to the experimental results, the maximum output voltage of the selected high-voltage module can reach 2.5 kV and has good output consistency. It can adapt to 16-36 V working voltage, and has excellent continuous working stability and temperature stability. It can meet the requirements of the development of pulsed neutron detectors.
The characteristics of high-voltage power supplies have a significant impact on the performance of the scintillation neutron detector. In order to overcome the problem of large volume and poor portability of traditional high-voltage power supply equipment, we used the internal integrated miniaturized high-voltage module to provide high-voltage for PMT in the development of portable pulsed neutron detector. According to the experimental results, the maximum output voltage of the selected high-voltage module can reach 2.5 kV and has good output consistency. It can adapt to 16-36 V working voltage, and has excellent continuous working stability and temperature stability. It can meet the requirements of the development of pulsed neutron detectors.
2019,
31: 035101.
doi: 10.11884/HPLPB201931.180368
Abstract:
To measure the closed orbit distortion of the beam in Lanzhou Heavy Ion accelerator Cooling Storage Ring main ring (CSRm) and perform closed orbit correction, the authors have developed a closed orbit correction system. It consists of an orbit measure system, a closed orbit control system and a corrector magnet system. The orbit measure system realizes real-time monitoring of the beam orbit; the closed orbit control system reads the orbit information, performs the closed orbit correction calculation, and transmits the calculated correction value to the corrector magnet system; the corrector magnet system changes the intensity of the corrector magnet by changing the settings of the corrector power supply, thereby realizing the adjustment of the beam orbit. The simulation test show that the maximum distortion in the horizontal direction is reduced from 3.37 mm to 0.39 mm, and the maximum distortion in the vertical direction is reduced from 4.21 mm to 0.31 mm. The system can measure the response matrix and correct the beam orbit automatically. It meets the design requirements.
To measure the closed orbit distortion of the beam in Lanzhou Heavy Ion accelerator Cooling Storage Ring main ring (CSRm) and perform closed orbit correction, the authors have developed a closed orbit correction system. It consists of an orbit measure system, a closed orbit control system and a corrector magnet system. The orbit measure system realizes real-time monitoring of the beam orbit; the closed orbit control system reads the orbit information, performs the closed orbit correction calculation, and transmits the calculated correction value to the corrector magnet system; the corrector magnet system changes the intensity of the corrector magnet by changing the settings of the corrector power supply, thereby realizing the adjustment of the beam orbit. The simulation test show that the maximum distortion in the horizontal direction is reduced from 3.37 mm to 0.39 mm, and the maximum distortion in the vertical direction is reduced from 4.21 mm to 0.31 mm. The system can measure the response matrix and correct the beam orbit automatically. It meets the design requirements.
2019,
31: 035102.
doi: 10.11884/HPLPB201931.180333
Abstract:
This paper presents the first time application of close-range photogrammetry to control net and components measurement in domestic particle accelerator facilities. A detailed measurement scheme is formulated to meet the narrow space of the tunnel, two kind of targets are designed (the hemisphere target and five plane faces target) and an idea is put forward to make the planar coded targets into a three dimensional group to satisfy the tunnel condition. Besides short baseline of a standard bar, long baseline based on laser tracker was also added for constraint. A measurement experiment was conducted in the 70 m long tunnel which is a part of RCS in CSNS, and the coordinates of the control points and the components are successfully obtained, the accuracy was 0.5 mm as compared with that of the laser tracker. This photogrammetric method has remarkably improved efficiency and achieved good result as expected.
This paper presents the first time application of close-range photogrammetry to control net and components measurement in domestic particle accelerator facilities. A detailed measurement scheme is formulated to meet the narrow space of the tunnel, two kind of targets are designed (the hemisphere target and five plane faces target) and an idea is put forward to make the planar coded targets into a three dimensional group to satisfy the tunnel condition. Besides short baseline of a standard bar, long baseline based on laser tracker was also added for constraint. A measurement experiment was conducted in the 70 m long tunnel which is a part of RCS in CSNS, and the coordinates of the control points and the components are successfully obtained, the accuracy was 0.5 mm as compared with that of the laser tracker. This photogrammetric method has remarkably improved efficiency and achieved good result as expected.
2019,
31: 036001.
doi: 10.11884/HPLPB201931.180284
Abstract:
Safety analysis in reactor scale on high tritium breeding blanket based on China Fusion Engineering Test Reactor (CFETR) was carried out with system analysis code RELAP5/Mod 3.4. In view of the complexity of blanket internal structure, an equivalent modeling method for complex flow and heat transfer structures of two cooling systems was proposed, and a heat transfer model between two cooling systems was established. The intact reactor model was completed on the basis, and verified the parameters on the steady-state operation. Then the analysis of loss of flow accident LOFA in fuel zone was performed. The computational results indicate that the sectional decay heat generated by the zone can be taken away by the FW-Tritium breeding zone cooling system, and every thermal-hydraulic parameter is under the limit. The blanket can resist this accident efficiently, and possess excellent thermal safety characteristics. The study also provides a reference for the safety analysis of other blankets in reactor scale.
Safety analysis in reactor scale on high tritium breeding blanket based on China Fusion Engineering Test Reactor (CFETR) was carried out with system analysis code RELAP5/Mod 3.4. In view of the complexity of blanket internal structure, an equivalent modeling method for complex flow and heat transfer structures of two cooling systems was proposed, and a heat transfer model between two cooling systems was established. The intact reactor model was completed on the basis, and verified the parameters on the steady-state operation. Then the analysis of loss of flow accident LOFA in fuel zone was performed. The computational results indicate that the sectional decay heat generated by the zone can be taken away by the FW-Tritium breeding zone cooling system, and every thermal-hydraulic parameter is under the limit. The blanket can resist this accident efficiently, and possess excellent thermal safety characteristics. The study also provides a reference for the safety analysis of other blankets in reactor scale.
2019,
31: 036002.
doi: 10.11884/HPLPB201931.180271
Abstract:
Large superconducting fusion device is used for testing the property of large superconducting magnetic load. When the quench happens in the operating phase, huge energy will be stored inside superconducting load. Therefore, energy inside must be transferred and released immediately by quench protection system. In the quench protection system, the fast discharge resistor system works for the energy absorbing and releasing by heat-dissipating. Due to the transferring energy, duration, power parameters of testing load, the designed system could adjust operating phase by changing structure connections. In addition, the analysis of system design and modular structure design are discussed and the anti-electromagnetic force, structure support simulation are demonstrated by FEA software, thus the feasibility of fast discharge resistor system can be verified.
Large superconducting fusion device is used for testing the property of large superconducting magnetic load. When the quench happens in the operating phase, huge energy will be stored inside superconducting load. Therefore, energy inside must be transferred and released immediately by quench protection system. In the quench protection system, the fast discharge resistor system works for the energy absorbing and releasing by heat-dissipating. Due to the transferring energy, duration, power parameters of testing load, the designed system could adjust operating phase by changing structure connections. In addition, the analysis of system design and modular structure design are discussed and the anti-electromagnetic force, structure support simulation are demonstrated by FEA software, thus the feasibility of fast discharge resistor system can be verified.
2019,
31: 036003.
doi: 10.11884/HPLPB201931.180283
Abstract:
In order to meet the requirements of nuclear fusion experiments, the converter is required in the design of the next generation tokamak to output instantaneous high-intensity pulsed current for providing type test dynamic and thermal stability in large electrical equipment. In this paper, a method of equating the impedance of the power supply system to the secondary side of the transformer and combining the voltage change relationship at both ends of the converter is presented. The total output current of several converters is obtained by calculation in different electrical parameters. The calculating process and results of electrical parameters meeting the requirements are given when the output current is 1 MA. The results are the limit condition under the given parameter, which makes the minimum design threshold in the high-power converter impulse current design, and lays the foundation for the following converter device selection and structure design.
In order to meet the requirements of nuclear fusion experiments, the converter is required in the design of the next generation tokamak to output instantaneous high-intensity pulsed current for providing type test dynamic and thermal stability in large electrical equipment. In this paper, a method of equating the impedance of the power supply system to the secondary side of the transformer and combining the voltage change relationship at both ends of the converter is presented. The total output current of several converters is obtained by calculation in different electrical parameters. The calculating process and results of electrical parameters meeting the requirements are given when the output current is 1 MA. The results are the limit condition under the given parameter, which makes the minimum design threshold in the high-power converter impulse current design, and lays the foundation for the following converter device selection and structure design.
2019,
31: 036004.
doi: 10.11884/HPLPB201931.180282
Abstract:
The accuracy of diode model in the demagnetization protecting circuits has the impact on the results of the circuits calculation design and analysis. This paper presents the calculation of current response and power dissipation of the demagnetization protecting circuits by using the equivalent voltage source model and the equivalent resistor model of diode group firstly. Then a new nonlinear model is proposed based on curve fitting method of current-voltage characteristic of the real diode to overcome the disadvantages of two diode models and improve the accuracy of calculation. Finally, the simulation results proved that the equivalent voltage source model and the nonlinear model have better effects on calculation and analysis.
The accuracy of diode model in the demagnetization protecting circuits has the impact on the results of the circuits calculation design and analysis. This paper presents the calculation of current response and power dissipation of the demagnetization protecting circuits by using the equivalent voltage source model and the equivalent resistor model of diode group firstly. Then a new nonlinear model is proposed based on curve fitting method of current-voltage characteristic of the real diode to overcome the disadvantages of two diode models and improve the accuracy of calculation. Finally, the simulation results proved that the equivalent voltage source model and the nonlinear model have better effects on calculation and analysis.
