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RSS2017 Vol. 29, No. 05
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2017,
29: 051001.
doi: 10.11884/HPLPB201729.160523
Abstract:
The hydrogen vibrational stimulated Raman scattering (SRS) pumped by a photolytic iodine laser (PIL) has been demonstrated for the first time. Under the condition of PIL pulse energy of 100-130 mJ (100 ns), double pass configuration is applied to reduce the SRS threshold successfully. SRS laser of 2900 nm is obtained and the photon conversion efficiency reaches 8.7%. The conversion efficiency of the first stokes light is found not affected by the pressure of hydrogen, once it is more than 1 MPa. Theoretical analysis is applied to explain this phenomenon.
The hydrogen vibrational stimulated Raman scattering (SRS) pumped by a photolytic iodine laser (PIL) has been demonstrated for the first time. Under the condition of PIL pulse energy of 100-130 mJ (100 ns), double pass configuration is applied to reduce the SRS threshold successfully. SRS laser of 2900 nm is obtained and the photon conversion efficiency reaches 8.7%. The conversion efficiency of the first stokes light is found not affected by the pressure of hydrogen, once it is more than 1 MPa. Theoretical analysis is applied to explain this phenomenon.
2017,
29: 051002.
doi: 10.11884/HPLPB201729.160465
Abstract:
This article presents the measurement of Ar metastable 1s5(3s23p54s［3/2］2) particle number density in He-Ar mixed gas at atmospheric pressure by the emission spectroscopy of the gas radiofrequency capacitive discharge. The important parameters of discharge plasma, gas rotational temperature, electron excitation temperature, and Ar metastable 1s5 particle number density, are measured at different discharge powers and gas composition. The results show that gas temperature changes little at different discharge power with the content of Ar less than 5103 Pa, and the range is 300-350 K. Electron excitation temperature increases with the increase of discharge power and the maximum is in 4103 Pa Ar admixture in the same discharge power and it is 0.58 eV at 70 W of the discharge power. 1s5 particle number density increases with the increase of discharge power and electron excitation temperature and it is 1.53109 cm-3 at 70 W of the discharge power with 4103 Pa Ar admixture.
This article presents the measurement of Ar metastable 1s5(3s23p54s［3/2］2) particle number density in He-Ar mixed gas at atmospheric pressure by the emission spectroscopy of the gas radiofrequency capacitive discharge. The important parameters of discharge plasma, gas rotational temperature, electron excitation temperature, and Ar metastable 1s5 particle number density, are measured at different discharge powers and gas composition. The results show that gas temperature changes little at different discharge power with the content of Ar less than 5103 Pa, and the range is 300-350 K. Electron excitation temperature increases with the increase of discharge power and the maximum is in 4103 Pa Ar admixture in the same discharge power and it is 0.58 eV at 70 W of the discharge power. 1s5 particle number density increases with the increase of discharge power and electron excitation temperature and it is 1.53109 cm-3 at 70 W of the discharge power with 4103 Pa Ar admixture.
2017,
29: 051003.
doi: 10.11884/HPLPB201729.160526
Abstract:
Ultrafast imaging system based on optical time-division multiplexing is proposed. A femtosecond fiber laser with center wavelength 1557 nm and pulse width about 90 fs, is used in the line-scan imaging system at 38.88 MHz for observing the USAF-1951 standard resolution test target. Based on the serial time-encoded amplified microscopy (STEAM) technology with the optical time-division multiplexing to achieve high resolution of ultrafast imaging, the imaging system has two times the sampling rate and the pixel number of the image is doubled. The result of the experiment demonstrates that the imaging system has achieved 20 GHz sampling rate by employing a 10 GHz of digital sampling device and doubling the sampling points comparing with the conventional ultrafast imaging system. The problem of low pixel number is addressed and image quality is enhanced effectively.
Ultrafast imaging system based on optical time-division multiplexing is proposed. A femtosecond fiber laser with center wavelength 1557 nm and pulse width about 90 fs, is used in the line-scan imaging system at 38.88 MHz for observing the USAF-1951 standard resolution test target. Based on the serial time-encoded amplified microscopy (STEAM) technology with the optical time-division multiplexing to achieve high resolution of ultrafast imaging, the imaging system has two times the sampling rate and the pixel number of the image is doubled. The result of the experiment demonstrates that the imaging system has achieved 20 GHz sampling rate by employing a 10 GHz of digital sampling device and doubling the sampling points comparing with the conventional ultrafast imaging system. The problem of low pixel number is addressed and image quality is enhanced effectively.
2017,
29: 051004.
doi: 10.11884/HPLPB201729.160540
Abstract:
This paper presents a method of annular beam nonlinear beam shaping by aspherical mirrors. The beam shaping system which contains two high-order aspherical mirrors can adjust the obscuration ratio and intensity distribution easily on the premise that there is almost no power loss. This method can realize mutual transformations come true between solid beams and hollow beams. Experimental results show that the method provides a good way for nonlinear beam shaping, and the optical path by this method agree well with theoretical analysis result.
This paper presents a method of annular beam nonlinear beam shaping by aspherical mirrors. The beam shaping system which contains two high-order aspherical mirrors can adjust the obscuration ratio and intensity distribution easily on the premise that there is almost no power loss. This method can realize mutual transformations come true between solid beams and hollow beams. Experimental results show that the method provides a good way for nonlinear beam shaping, and the optical path by this method agree well with theoretical analysis result.
2017,
29: 051005.
doi: 10.11884/HPLPB201729.160503
Abstract:
For the purpose of overcoming the disadvantages, such as low adjusting efficiency and complicated operating procedures, in most of current ultra-short and ultra-high-intensity laser experiments, an integrated and simple system for laser path adjusting was designed based on LabVIEW software. This system was consisted of three modules, which were named as laser spot acquiring module, laser path position adjusting module and industry computer respectively. In this system, the pointing of laser path was decided by the position of laser incident on CCD camera, and the adjusting of light path in vacuum was accomplished by a person-machine interface. Meanwhile, simultaneous multi-route running has been achieved in this system, and moving stage controllers of different models or communication styles have been integrated in the same interface. Experiments show that this system could be a better choice for more convenient adjusting of laser path and higher efficiency of ultra-short and ultra-high-intensity laser experiments.
For the purpose of overcoming the disadvantages, such as low adjusting efficiency and complicated operating procedures, in most of current ultra-short and ultra-high-intensity laser experiments, an integrated and simple system for laser path adjusting was designed based on LabVIEW software. This system was consisted of three modules, which were named as laser spot acquiring module, laser path position adjusting module and industry computer respectively. In this system, the pointing of laser path was decided by the position of laser incident on CCD camera, and the adjusting of light path in vacuum was accomplished by a person-machine interface. Meanwhile, simultaneous multi-route running has been achieved in this system, and moving stage controllers of different models or communication styles have been integrated in the same interface. Experiments show that this system could be a better choice for more convenient adjusting of laser path and higher efficiency of ultra-short and ultra-high-intensity laser experiments.
2017,
29: 052001.
doi: 10.11884/HPLPB201729.170042
Abstract:
The optical signals are converted into electrical signals of same time characteristics by the technique of the in-situ spectroscopic detection. The switch-on time is obtained by calculating the time difference of the exciting and electrical signals. Results show that the proposed method can effectively measure the switch-on time of DC and HF AC plasma antennas. The switch-on time of plasma antennas driven by DC and kHz AC power supplies are about 1 ms, and that of plasma antennas driven by MHz power supplies are approximately 0.5 ms. The error of 50 Hz AC plasma antenna is very large due to the unstable discharge state. The value of switch-on time is greatly related to the exciting power and the response time of the power supplies. In a certain range, with the increase of discharge power, the switch-on time of the antenna is shortened. Besides, the error is reduced by about 1%-2%.
The optical signals are converted into electrical signals of same time characteristics by the technique of the in-situ spectroscopic detection. The switch-on time is obtained by calculating the time difference of the exciting and electrical signals. Results show that the proposed method can effectively measure the switch-on time of DC and HF AC plasma antennas. The switch-on time of plasma antennas driven by DC and kHz AC power supplies are about 1 ms, and that of plasma antennas driven by MHz power supplies are approximately 0.5 ms. The error of 50 Hz AC plasma antenna is very large due to the unstable discharge state. The value of switch-on time is greatly related to the exciting power and the response time of the power supplies. In a certain range, with the increase of discharge power, the switch-on time of the antenna is shortened. Besides, the error is reduced by about 1%-2%.
2017,
29: 053001.
doi: 10.11884/HPLPB201729.170043
Abstract:
The scattering features of microwave by inhomogeneous plasma column have been studied numerically by the Finite-difference-time-domain(FDTD) method and experimentally. The effects of the plasma frequency and electron collision rate on microwave's reflectance, transmittance and absorptance were tested. The results show the plasma column with plasma density of non-uniform distribution can make the scattering wave shift away from 0 to a side-angled direction. The electron density and the collision rate play an important role in the reduction of the wave reflection. The plasma density should be appropriate, even be lower than the critical value corresponding to the microwave, so that the microwave can reduce greatly in reflectance due to the strong scattering or absorption.
The scattering features of microwave by inhomogeneous plasma column have been studied numerically by the Finite-difference-time-domain(FDTD) method and experimentally. The effects of the plasma frequency and electron collision rate on microwave's reflectance, transmittance and absorptance were tested. The results show the plasma column with plasma density of non-uniform distribution can make the scattering wave shift away from 0 to a side-angled direction. The electron density and the collision rate play an important role in the reduction of the wave reflection. The plasma density should be appropriate, even be lower than the critical value corresponding to the microwave, so that the microwave can reduce greatly in reflectance due to the strong scattering or absorption.
2017,
29: 053002.
doi: 10.11884/HPLPB201729.170024
Abstract:
Analog to Digital Converter (ADC) is widely used in measurement and control systems, the electromagnetic susceptibility problem of embedded ADC has been gradually highlighted in complex environment. The ambient temperature effect on electromagnetic susceptibility is analyzed by theoretical analysis and experimental measurement. Combined with the structure and characteristic of ADC, the mechanism of radio frequency interference signal disturbing ADC is analyzed. The influence of temperature effect on drain current of metal-oxide-semiconductor(MOS) transistors under interference signal is pointed out. At different temperatures, the circuit parameters of each part are measured and analyzed under electromagnetic interference. The temperature effect on ADC electromagnetic susceptibility is measured within the frequency range from 10 MHz to 1 GHz and the temperature range from -10 ℃ to 80 ℃. Results show that the changing ambient temperature changes the response of ADC under electromagnetic interference by altering the mobility of MOS transistors, causing significant drift of electromagnetic susceptibility.
Analog to Digital Converter (ADC) is widely used in measurement and control systems, the electromagnetic susceptibility problem of embedded ADC has been gradually highlighted in complex environment. The ambient temperature effect on electromagnetic susceptibility is analyzed by theoretical analysis and experimental measurement. Combined with the structure and characteristic of ADC, the mechanism of radio frequency interference signal disturbing ADC is analyzed. The influence of temperature effect on drain current of metal-oxide-semiconductor(MOS) transistors under interference signal is pointed out. At different temperatures, the circuit parameters of each part are measured and analyzed under electromagnetic interference. The temperature effect on ADC electromagnetic susceptibility is measured within the frequency range from 10 MHz to 1 GHz and the temperature range from -10 ℃ to 80 ℃. Results show that the changing ambient temperature changes the response of ADC under electromagnetic interference by altering the mobility of MOS transistors, causing significant drift of electromagnetic susceptibility.
2017,
29: 053101.
doi: 10.11884/HPLPB201729.160370
Abstract:
The terahertz mixer is a key component of the terahertz wave transmitting system, which could transform the frequency of signal from one value to another. The Schottky diode is the core part of the mixer. In addition to the Schottky diode, other units such as low pass filter and LO port, also play critical roles in the THz mixer. This article analyzes the key parts of the terahertz mixer, including the waveguide, Schottky diode and low pass filters by High Frequency Structure Simulator (HFSS). Through the analysis of simulation results, the terahertz mixer model of 0.38 THz is achieved.
The terahertz mixer is a key component of the terahertz wave transmitting system, which could transform the frequency of signal from one value to another. The Schottky diode is the core part of the mixer. In addition to the Schottky diode, other units such as low pass filter and LO port, also play critical roles in the THz mixer. This article analyzes the key parts of the terahertz mixer, including the waveguide, Schottky diode and low pass filters by High Frequency Structure Simulator (HFSS). Through the analysis of simulation results, the terahertz mixer model of 0.38 THz is achieved.
2017,
29: 053201.
doi: 10.11884/HPLPB201729.170011
Abstract:
The three-wave nonlinear effect of radio wave propagation in plasma is one possible solution to the problem of black out. Base on three-wave nonlinear theory, the method for calculating the conversion efficiency is introduced and the nonlinear effect under different plasma electron density model are analyzed. The results of numerical simulation show that there is an optimal signal incident angle, at which the conversion efficiency is maximum; when the thickness of plasma is reduced, the optimal signal incident angle is increased; the larger the derivation value in resonance point of plasma electron density, the greater the nonlinear effect, while the other parameters are identical.
The three-wave nonlinear effect of radio wave propagation in plasma is one possible solution to the problem of black out. Base on three-wave nonlinear theory, the method for calculating the conversion efficiency is introduced and the nonlinear effect under different plasma electron density model are analyzed. The results of numerical simulation show that there is an optimal signal incident angle, at which the conversion efficiency is maximum; when the thickness of plasma is reduced, the optimal signal incident angle is increased; the larger the derivation value in resonance point of plasma electron density, the greater the nonlinear effect, while the other parameters are identical.
2017,
29: 053203.
doi: 10.11884/HPLPB201729.170008
Abstract:
The influence of two short equivalent lines length on the accuracy of the asymptotic method for analysing electromagnetic field coupling to transmission line at high frequency is investigated in detail. Firstly, the induced current distribution along the transmission line in terms of different lengths of two short lines is analyzed through numbers of calculations. It is indicated that the calculated induced current along the line by asymptotic method is not reliable when any one of the short equivalent lines is half wavelength long. Secondly, the dependence of the two short equivalent lines on the whole transmission line length is studied. Results show that when the length of the transmission line is much longer than the distance between two conductors, it is necessary to increase the suggested lengths of the equivalent short lines in order to get more accurate induced current along the line.
The influence of two short equivalent lines length on the accuracy of the asymptotic method for analysing electromagnetic field coupling to transmission line at high frequency is investigated in detail. Firstly, the induced current distribution along the transmission line in terms of different lengths of two short lines is analyzed through numbers of calculations. It is indicated that the calculated induced current along the line by asymptotic method is not reliable when any one of the short equivalent lines is half wavelength long. Secondly, the dependence of the two short equivalent lines on the whole transmission line length is studied. Results show that when the length of the transmission line is much longer than the distance between two conductors, it is necessary to increase the suggested lengths of the equivalent short lines in order to get more accurate induced current along the line.
2017,
29: 054101.
doi: 10.11884/HPLPB201729.160548
Abstract:
The loaded quality factor (QL) of the film bulk acoustic resonator(FBAR) oscillator and the quality factor (Q value) of FBAR are related to the frequency stability of FBAR oscillator. In order to study the effect of the two kinds of quality factors on the frequency stability, the multi physical field model of FBAR was established in the COMSOL multiphysics software. The parameters of the modified Butterworth-Van Dyke (MBVD) model were got by frequency domain simulation and model parameter fitting. A model of MBVD circuit was established in the ADS software, and Q value for different loss was obtained by the simulation of S parameters and computing the corresponding Q value with the Bode method. The Pierce-based oscillator was established and simulated with the harmonic balance, thus the phase noise was obtained by changing QL and Q, and the effect of the two factors on frequency stability was got. The results show that the frequency stability increased with the increase of QL and Q, Q decreased with the increase of different losses. If the Q is lower than 338, the effect of increasing QL to improve the frequency stability is poor. Using this kind of FBAR to construct oscillator will not meet the requirements of FBAR wireless communication RF front-end as the reference signal source and the readout circuit of FBAR sensor. This paper provides a reference for FBAR frequency reference design and FBAR sensor readout circuit.
The loaded quality factor (QL) of the film bulk acoustic resonator(FBAR) oscillator and the quality factor (Q value) of FBAR are related to the frequency stability of FBAR oscillator. In order to study the effect of the two kinds of quality factors on the frequency stability, the multi physical field model of FBAR was established in the COMSOL multiphysics software. The parameters of the modified Butterworth-Van Dyke (MBVD) model were got by frequency domain simulation and model parameter fitting. A model of MBVD circuit was established in the ADS software, and Q value for different loss was obtained by the simulation of S parameters and computing the corresponding Q value with the Bode method. The Pierce-based oscillator was established and simulated with the harmonic balance, thus the phase noise was obtained by changing QL and Q, and the effect of the two factors on frequency stability was got. The results show that the frequency stability increased with the increase of QL and Q, Q decreased with the increase of different losses. If the Q is lower than 338, the effect of increasing QL to improve the frequency stability is poor. Using this kind of FBAR to construct oscillator will not meet the requirements of FBAR wireless communication RF front-end as the reference signal source and the readout circuit of FBAR sensor. This paper provides a reference for FBAR frequency reference design and FBAR sensor readout circuit.
2017,
29: 055001.
doi: 10.11884/HPLPB201729.170001
Abstract:
An uncertainty model has been proposed which is based on the black-box concept to evaluate the uncertainty of measurement and calibration in high voltage pulse divider. The initial model was proposed in principle, unnecessary variables in the formula could be omissible in the calibration experiment. For the model absent of uncertainty originating from calibration document, and resolving power of oscilloscope, the correction components which belong to the black-box model would be introduced to the formula to perfect the model. The uncertainties were combined after perfection of model according to the law of propagation of uncertainty. The results are compared with that combined from relative uncertainty. It is shown that the uncertainty combined from relative uncertainty will be correct if this model is only composed of multiplication and division of different variables, or addition and subtraction of different variables are also permitted if the mathematical expectation values of these items equal to zero. This is proven by calculating the voltage potential between two different positions according to the measured voltage pulse at those positions and analyzing the attenuation represented by dB scales. In the calibration experiment of high voltage divider, the combined standard uncertainty of dividers scaling factor is obtained by evaluating Type A standard uncertainty of the ratio of output to input. The influence of dispersion from signal source output on evaluation of standard uncertainty can be weakened with this method.
An uncertainty model has been proposed which is based on the black-box concept to evaluate the uncertainty of measurement and calibration in high voltage pulse divider. The initial model was proposed in principle, unnecessary variables in the formula could be omissible in the calibration experiment. For the model absent of uncertainty originating from calibration document, and resolving power of oscilloscope, the correction components which belong to the black-box model would be introduced to the formula to perfect the model. The uncertainties were combined after perfection of model according to the law of propagation of uncertainty. The results are compared with that combined from relative uncertainty. It is shown that the uncertainty combined from relative uncertainty will be correct if this model is only composed of multiplication and division of different variables, or addition and subtraction of different variables are also permitted if the mathematical expectation values of these items equal to zero. This is proven by calculating the voltage potential between two different positions according to the measured voltage pulse at those positions and analyzing the attenuation represented by dB scales. In the calibration experiment of high voltage divider, the combined standard uncertainty of dividers scaling factor is obtained by evaluating Type A standard uncertainty of the ratio of output to input. The influence of dispersion from signal source output on evaluation of standard uncertainty can be weakened with this method.
2017,
29: 055002.
doi: 10.11884/HPLPB201729.160457
Abstract:
Electron Cyclotron Resonance Heating (ECRH) system is one of the most important Tokamak auxiliary heating methods. However, with the development of physical experiments progress, there are growing stringent requirements for ECRH system and high-voltage power supply system, at the same time, more difficulty of the control and protection of high-voltage power supply. In this paper, according to the requirements of -60 kV/50 A PSM high-voltage power supply, a control system based on MCU and FPGA is developed, which not only satisfies all working modes of the power supply system, especially the requirements of 1 kHz modulation, but also meets the requirements of logic control and fast protection for gyrotron test bench. The experimental results show good logic structure and reliable operation of the power supply and control system and it can fit the requirements of logic control, timing and fast protection for gyrotron test bench.
Electron Cyclotron Resonance Heating (ECRH) system is one of the most important Tokamak auxiliary heating methods. However, with the development of physical experiments progress, there are growing stringent requirements for ECRH system and high-voltage power supply system, at the same time, more difficulty of the control and protection of high-voltage power supply. In this paper, according to the requirements of -60 kV/50 A PSM high-voltage power supply, a control system based on MCU and FPGA is developed, which not only satisfies all working modes of the power supply system, especially the requirements of 1 kHz modulation, but also meets the requirements of logic control and fast protection for gyrotron test bench. The experimental results show good logic structure and reliable operation of the power supply and control system and it can fit the requirements of logic control, timing and fast protection for gyrotron test bench.
2017,
29: 055003.
doi: 10.11884/HPLPB201729.170040
Abstract:
A compact repetitive pulsed power system on the basis of fast Marx generator was developed in order to realize pulsed power device miniaturization. It is mainly composed of fast Marx generator and trigger pulse supply. There are polypropylene film capacitors with plastic shell, miniaturized gas switches, isolated inductors and SF6 gas insulation in the 18-stage fast Marx generator, whose storage energy density is 25.7 kJ/m3. An 8-stage Marx generator circuit is utilized in trigger pulse supply with the maximal output voltage of 80 kV and pulse duration of about 500 ns. The compact pulsed power source integrated has a volume of about 0.2 m3. In single pulse operation mode, the voltage of output pulse on an 18 resistor load is up to 765 kV with the pulse width (FWHM) of 162 ns, the rising time of 54 ns and the power density of 157 GW/m3. In repetitive mode with the rate of 5 Hz, the average peak voltage of 5 successive pulses is about 550 kV because of being limited by repetitive charging voltages. The pulsed power source can apply to biology, medical research and so on. This work can also provide experience for building a repetitive high pulsed power system with high performance.
A compact repetitive pulsed power system on the basis of fast Marx generator was developed in order to realize pulsed power device miniaturization. It is mainly composed of fast Marx generator and trigger pulse supply. There are polypropylene film capacitors with plastic shell, miniaturized gas switches, isolated inductors and SF6 gas insulation in the 18-stage fast Marx generator, whose storage energy density is 25.7 kJ/m3. An 8-stage Marx generator circuit is utilized in trigger pulse supply with the maximal output voltage of 80 kV and pulse duration of about 500 ns. The compact pulsed power source integrated has a volume of about 0.2 m3. In single pulse operation mode, the voltage of output pulse on an 18 resistor load is up to 765 kV with the pulse width (FWHM) of 162 ns, the rising time of 54 ns and the power density of 157 GW/m3. In repetitive mode with the rate of 5 Hz, the average peak voltage of 5 successive pulses is about 550 kV because of being limited by repetitive charging voltages. The pulsed power source can apply to biology, medical research and so on. This work can also provide experience for building a repetitive high pulsed power system with high performance.
2017,
29: 055004.
doi: 10.11884/HPLPB201729.160544
Abstract:
The magnetic compression system (MAGO) proposed by VNIIEF is a new concept of nuclear fusion. The impurities in magnetic compression system may come from thermal desorption process, and wall materials washout by plasma. In this paper, combined with the 2-D temperature distribution of anodic electrode for 5 MA pulsed current flowing through gas pondermotor unit, the impurities generated from thermal desorption process in MAGO chamber were analyzed, consulted to the impurities desorption of copper sample. The TOF spectrum of 3 keV Ar+ scattering from Cu(110), Cu(111) surfaces were measured, and the impurity elements on copper surface were analyzed. According to the results, impurities desorption depends on the temperature and the surface structure of anodic electrode.
The magnetic compression system (MAGO) proposed by VNIIEF is a new concept of nuclear fusion. The impurities in magnetic compression system may come from thermal desorption process, and wall materials washout by plasma. In this paper, combined with the 2-D temperature distribution of anodic electrode for 5 MA pulsed current flowing through gas pondermotor unit, the impurities generated from thermal desorption process in MAGO chamber were analyzed, consulted to the impurities desorption of copper sample. The TOF spectrum of 3 keV Ar+ scattering from Cu(110), Cu(111) surfaces were measured, and the impurity elements on copper surface were analyzed. According to the results, impurities desorption depends on the temperature and the surface structure of anodic electrode.
2017,
29: 056001.
doi: 10.11884/HPLPB201729.160559
Abstract:
The high breeding ratio blanket can obtain tritium breeding ratio over 1.5 and energy magnifying factor about 5, the fuel zone has power density more than 50 MW/m3 on average. According to the characteristic of high power density region in the blanket, this paper present the design of a circuitous flow cooling system, which is featured with inserted cooling tubes and the collecting-distributing manifolds. The thermal-hydraulic analysis has been conducted on this cooling system. A 3-D model consisting of the first wall and the fuel zone were established, the CFD code FLUENT were used to simulate the blanket under steady operating condition. As the numerical results show, this conceptual cooling system has a satisfying flow distribution, the pressure drop of coolant in whole fuel zone is 102 kPa, and the outlet temperature is 594 K, which meet the design expectation well. The maximum temperatures of all blanket structures are below the temperature limits, which indicates that the cooling system could carry the fission generated heat out effectively.
The high breeding ratio blanket can obtain tritium breeding ratio over 1.5 and energy magnifying factor about 5, the fuel zone has power density more than 50 MW/m3 on average. According to the characteristic of high power density region in the blanket, this paper present the design of a circuitous flow cooling system, which is featured with inserted cooling tubes and the collecting-distributing manifolds. The thermal-hydraulic analysis has been conducted on this cooling system. A 3-D model consisting of the first wall and the fuel zone were established, the CFD code FLUENT were used to simulate the blanket under steady operating condition. As the numerical results show, this conceptual cooling system has a satisfying flow distribution, the pressure drop of coolant in whole fuel zone is 102 kPa, and the outlet temperature is 594 K, which meet the design expectation well. The maximum temperatures of all blanket structures are below the temperature limits, which indicates that the cooling system could carry the fission generated heat out effectively.
2017,
29: 056002.
doi: 10.11884/HPLPB201729.160283
Abstract:
The fuel cladding is the first barrier of nuclear power plant. Once it failed, fission products would release to reactor coolant system (RCS) through the crevasse. So determining the general position and size of the crevasse would help a lot to know the seriousness of the accident. This paper builds four models, which are models for cases of fission products accumulated in fuel pellets, diffused to the gap between pellet and cladding and released from the gap to RCS, and the balance model in RCS. By detecting the activities of fission products in RCS, we can deduce the initial products released from the crevasse and subsequently the specific situation of the crevasse. These models have been proved applicable by an accident of fuel rod failure in the Daya Bay Nuclear Power Plant.
The fuel cladding is the first barrier of nuclear power plant. Once it failed, fission products would release to reactor coolant system (RCS) through the crevasse. So determining the general position and size of the crevasse would help a lot to know the seriousness of the accident. This paper builds four models, which are models for cases of fission products accumulated in fuel pellets, diffused to the gap between pellet and cladding and released from the gap to RCS, and the balance model in RCS. By detecting the activities of fission products in RCS, we can deduce the initial products released from the crevasse and subsequently the specific situation of the crevasse. These models have been proved applicable by an accident of fuel rod failure in the Daya Bay Nuclear Power Plant.
2017,
29: 056003.
doi: 10.11884/HPLPB201729.160397
Abstract:
In reactor design and safety analysis, the statistical error of Monte Carlo code often covers the actual reactivity difference between two systems with only a little difference. Generally, perturbation method is used to solve this problem. In this work, reactivity perturbation is implemented into JMCT code. High order perturbations and fission source perturbation are considered in order to get a high precision. Models with global perturbation and local perturbation are tested. The systems with fast and thermal neutron spectrum are also tested. Some of the above models have positive reactivity perturbations, while others have negative perturbations.
In reactor design and safety analysis, the statistical error of Monte Carlo code often covers the actual reactivity difference between two systems with only a little difference. Generally, perturbation method is used to solve this problem. In this work, reactivity perturbation is implemented into JMCT code. High order perturbations and fission source perturbation are considered in order to get a high precision. Models with global perturbation and local perturbation are tested. The systems with fast and thermal neutron spectrum are also tested. Some of the above models have positive reactivity perturbations, while others have negative perturbations.
2017,
29: 056004.
doi: 10.11884/HPLPB201729.160205
Abstract:
The existing supercritical water-cooled Reactor (SCWR) undertakes a design of water rod assembly to solve the problem of neutron moderator insufficiency. However, this brings a giant challenge to engineering feasibility of the assembly and reactor core designs. This article presents a design of utilizing an assembly with mixed moderators that adopts the coolant (not floated and heated through the fuel region) and the solid moderator in fuel region to achieve the design target of abolishing water rod completely and simplifying the assembly design of SCWR. On the basis of analysis and calculation, compared with the water rod assembly, the assembly with mixed moderators has advantages of simple design, high capability of economy and safety.
The existing supercritical water-cooled Reactor (SCWR) undertakes a design of water rod assembly to solve the problem of neutron moderator insufficiency. However, this brings a giant challenge to engineering feasibility of the assembly and reactor core designs. This article presents a design of utilizing an assembly with mixed moderators that adopts the coolant (not floated and heated through the fuel region) and the solid moderator in fuel region to achieve the design target of abolishing water rod completely and simplifying the assembly design of SCWR. On the basis of analysis and calculation, compared with the water rod assembly, the assembly with mixed moderators has advantages of simple design, high capability of economy and safety.
2017,
29: 056005.
doi: 10.11884/HPLPB201729.160296
Abstract:
The NECP-SARAX code developed by NECP research team is used for the fast reactor analysis. In order to consider the complex neutron slowing down effects from scattering resonance of nuclides with medium mass and inelastic scattering, the Monte-Carlo method was used previously but brought big uncertainty in tallying the spectrum in low energy. Besides, the efficiency is extremely low. In the improvement, a new resonance method based on ultra-fine group and point-wise cross section was involved. It generated effective multi-group cross sections with similar accuracy of Monte-Carlo method but avoided its disadvantages. In the core calculation, the multi-group cross sections were used for the 3D transport calculation. The first-order and exact perturbation theories were used in calculating the reactivity coefficients of fast reactor. To be capable of handling the geometric distorting in fast reactor, a new pseudo density method based on neutron transport and perturbation theory was proposed. Both the point kinetic and quasi-steady method were used in the transient calculation as two options to fit the requirement of fast reactor and ADS. The OECD fast reactor benchmarks were tested to verify the SARAX code, the results show good accuracy in the fast reactor calculations, which is similar to other widely accepted fast reactor code. The relative error of keff is less than 300 pcm compared with the Monte-Carlo code. Based on the pseudo density model and three-dimensional spatially dependent kinetics model, the SARAX code has more complete functions to fit the requirements of fast reactor design better.
The NECP-SARAX code developed by NECP research team is used for the fast reactor analysis. In order to consider the complex neutron slowing down effects from scattering resonance of nuclides with medium mass and inelastic scattering, the Monte-Carlo method was used previously but brought big uncertainty in tallying the spectrum in low energy. Besides, the efficiency is extremely low. In the improvement, a new resonance method based on ultra-fine group and point-wise cross section was involved. It generated effective multi-group cross sections with similar accuracy of Monte-Carlo method but avoided its disadvantages. In the core calculation, the multi-group cross sections were used for the 3D transport calculation. The first-order and exact perturbation theories were used in calculating the reactivity coefficients of fast reactor. To be capable of handling the geometric distorting in fast reactor, a new pseudo density method based on neutron transport and perturbation theory was proposed. Both the point kinetic and quasi-steady method were used in the transient calculation as two options to fit the requirement of fast reactor and ADS. The OECD fast reactor benchmarks were tested to verify the SARAX code, the results show good accuracy in the fast reactor calculations, which is similar to other widely accepted fast reactor code. The relative error of keff is less than 300 pcm compared with the Monte-Carlo code. Based on the pseudo density model and three-dimensional spatially dependent kinetics model, the SARAX code has more complete functions to fit the requirements of fast reactor design better.
2017,
29: 056006.
doi: 10.11884/HPLPB201729.160184
Abstract:
Rossi- measurement is commonly used to determine the prompt neutron decay constant. The relation between prompt neutron decay constant and Rossi- distribution are established on the condition of weak neutron source. When the source intensity is high, the measurment could not provide correct result, due to the overlap of neutrons emitted from different sources. In order to quantitatively analyze the influence of neutron source intensity on Rossi- measurement, simulation tools to calculate the Rossi- distribution are developed on the basis of MCNP code. In this paper, two sketch models of subcritical systems, a reactor model and an accelerator driven system model, are simulated to illustrate the relation between the estimated prompt neutron decay constant and the source intensity. Simulation results indicate that when the neutron source has high intensity, the calculated prompt neutron constant will deviate from the actual results. For both subcritical reactor and accelerator driven system models, when the intensity of the neutron source is low, the prompt neutron decay constant could be obtained by Rossi- measurement, while, when the intensity is high, the measurement could not provide correct result of the constant. By studying the interrelationships of the source intensities and the measured results, the maximum usable intensity value which could provide correct measurement result could be obtained. It is possible to reduce the detection duration by choosing a relatively stronger usable neutron source within the range of the maximum usable intensity.
Rossi- measurement is commonly used to determine the prompt neutron decay constant. The relation between prompt neutron decay constant and Rossi- distribution are established on the condition of weak neutron source. When the source intensity is high, the measurment could not provide correct result, due to the overlap of neutrons emitted from different sources. In order to quantitatively analyze the influence of neutron source intensity on Rossi- measurement, simulation tools to calculate the Rossi- distribution are developed on the basis of MCNP code. In this paper, two sketch models of subcritical systems, a reactor model and an accelerator driven system model, are simulated to illustrate the relation between the estimated prompt neutron decay constant and the source intensity. Simulation results indicate that when the neutron source has high intensity, the calculated prompt neutron constant will deviate from the actual results. For both subcritical reactor and accelerator driven system models, when the intensity of the neutron source is low, the prompt neutron decay constant could be obtained by Rossi- measurement, while, when the intensity is high, the measurement could not provide correct result of the constant. By studying the interrelationships of the source intensities and the measured results, the maximum usable intensity value which could provide correct measurement result could be obtained. It is possible to reduce the detection duration by choosing a relatively stronger usable neutron source within the range of the maximum usable intensity.
2017,
29: 056007.
doi: 10.11884/HPLPB201729.160413
Abstract:
Geant4 is a Monte Carlo simulation program toolkit based on C++ object-oriented technique. The toolkit can simulate various interactions between particles and medium materials and has been widely applied in high energy physics, accelerator physics, etc. However, because of the lack of critical source function, Geant4 cannot be used directly in reactor physics. Using physics models and particle tracking and control functions provided by Geant4, we implemented criticality calculation in two ways and developed Geant4-based static reactor simulation code G4-RSM and dynamic reactor simulation code G4-RDM. Both codes can be used for criticality simulation and the relative errors are within 5% compared with MCNP. Except for criticality simulation, G4-RDM can be used to simulate neutron characteristics in reactor accident conditions.
Geant4 is a Monte Carlo simulation program toolkit based on C++ object-oriented technique. The toolkit can simulate various interactions between particles and medium materials and has been widely applied in high energy physics, accelerator physics, etc. However, because of the lack of critical source function, Geant4 cannot be used directly in reactor physics. Using physics models and particle tracking and control functions provided by Geant4, we implemented criticality calculation in two ways and developed Geant4-based static reactor simulation code G4-RSM and dynamic reactor simulation code G4-RDM. Both codes can be used for criticality simulation and the relative errors are within 5% compared with MCNP. Except for criticality simulation, G4-RDM can be used to simulate neutron characteristics in reactor accident conditions.
2017,
29: 056008.
doi: 10.11884/HPLPB201729.160552
Abstract:
Superconducting fragment separator HFRS is the significant facility to study the radioactive physics in High Intensity heavy-ion Accelerator Facility (HIAF). HFRS is an in-flight fragment separator, which has many unique features, such as large magnetic rigidity, large acceptance, big magnet aperture, high momentum resolving power and so on. HFRS uses the B-E-B method to separate the exotic nuclei produced by projectile fragmentation or fission within several hundred nanoseconds, which are used to investigate the high precision in-ring experiments or out-ring experiments. This presentation mainly introduces the separation performance of HFRS. It uses MOCADI program to simulate the purification of fragments in projectile fragmentation and fission products with one degrader stage or two degrader stages. The simulation results show that HFRS has good achromatic and focusing properties, and it can efficiently isolate and purify light nuclides via fragmentation with one degrader stage and it has a certain separation effect of heavier nuclides with two degrader stages. The momentum spread of fission is much higher than fragmentation, so the fission products separation effect of HFRS with two degrader stages is not as good as the fragment purification effect with single degrader stage.
Superconducting fragment separator HFRS is the significant facility to study the radioactive physics in High Intensity heavy-ion Accelerator Facility (HIAF). HFRS is an in-flight fragment separator, which has many unique features, such as large magnetic rigidity, large acceptance, big magnet aperture, high momentum resolving power and so on. HFRS uses the B-E-B method to separate the exotic nuclei produced by projectile fragmentation or fission within several hundred nanoseconds, which are used to investigate the high precision in-ring experiments or out-ring experiments. This presentation mainly introduces the separation performance of HFRS. It uses MOCADI program to simulate the purification of fragments in projectile fragmentation and fission products with one degrader stage or two degrader stages. The simulation results show that HFRS has good achromatic and focusing properties, and it can efficiently isolate and purify light nuclides via fragmentation with one degrader stage and it has a certain separation effect of heavier nuclides with two degrader stages. The momentum spread of fission is much higher than fragmentation, so the fission products separation effect of HFRS with two degrader stages is not as good as the fragment purification effect with single degrader stage.
2017,
29: 056009.
doi: 10.11884/HPLPB201729.160259
Abstract:
High temperature nuclear reactor in the field of MHD power generation and nuclear rockets have good application prospects. High temperature reactor has a pile of high core temperature, complex structures, whose physical performance parameters are rather difficult to compute. This paper studies the high temperature nuclear reactor prompt neutron generation time calculation method, introduces the calculation principle of a variety of methods and a new high temperature nuclear reactors calculation results. The results show that for the same reactor model, calculation results of several methods are in good agreement and the calculated results are credible.
High temperature nuclear reactor in the field of MHD power generation and nuclear rockets have good application prospects. High temperature reactor has a pile of high core temperature, complex structures, whose physical performance parameters are rather difficult to compute. This paper studies the high temperature nuclear reactor prompt neutron generation time calculation method, introduces the calculation principle of a variety of methods and a new high temperature nuclear reactors calculation results. The results show that for the same reactor model, calculation results of several methods are in good agreement and the calculated results are credible.
2017,
29: 056010.
doi: 10.11884/HPLPB201729.160274
Abstract:
The accuracy and efficiency of core physics calculation have a great impact on the safety of nuclear reactors. As reactor cores get more and more complex, diffusion theory presents low accuracy. Various transport methods are developed and studied. The even-parity discrete ordinates method(EPSN) needs less storage and less computing time due to a reduction in angular domain of one-half compared to the first-order transport equations. The new high-efficiency even-parity discrete ordinates(HEPSN) method is proposed based on optimizing the EPSN method. It is worth noting that HEPSN method only solves one-eighth of the angular domain. HEPSN method appears to have no negative flux, be easy to obtain consistent diffusion synthetic acceleration and have uncoupled reflective boundary conditions. The accuracy of HEPSN method for critical calculation is verified by TAKEDA benchmarks. The results show that the accuracy of HEPSN method is higher than diffusion theory and the computing time and the computer memory are less than EPSN method. HEPSN method has the potential to be applied to the calculations of large reactor cores.
The accuracy and efficiency of core physics calculation have a great impact on the safety of nuclear reactors. As reactor cores get more and more complex, diffusion theory presents low accuracy. Various transport methods are developed and studied. The even-parity discrete ordinates method(EPSN) needs less storage and less computing time due to a reduction in angular domain of one-half compared to the first-order transport equations. The new high-efficiency even-parity discrete ordinates(HEPSN) method is proposed based on optimizing the EPSN method. It is worth noting that HEPSN method only solves one-eighth of the angular domain. HEPSN method appears to have no negative flux, be easy to obtain consistent diffusion synthetic acceleration and have uncoupled reflective boundary conditions. The accuracy of HEPSN method for critical calculation is verified by TAKEDA benchmarks. The results show that the accuracy of HEPSN method is higher than diffusion theory and the computing time and the computer memory are less than EPSN method. HEPSN method has the potential to be applied to the calculations of large reactor cores.
2017,
29: 059001.
doi: 10.11884/HPLPB201729.170041
Abstract:
In order to make the best use of oxidants and UV irradiation in dielectric barrier discharge (DBD), catalyst sodium bismuthate was added into a rod-plate DBD reactor. The spectral characteristics of DBD and the effects of pH value, aniline initial concentration, and catalyst dosage on aniline degradation rate were investigated. The synergistic catalytic mechanism of aniline removal was discussed. The results show that the radiation of UV and visible light was produced in the discharge process, and the highest intensity spectral in the range of 300-450 nm is N2 second positive band line. The degradation efficiency of 100 mg/L aniline was improved after sodium bismuthate being added, and total organic carbon (TOC) removal was improved 14.11% with 0.2 g/L catalyst addition. Under alkaline condition, the degradation rates of aniline and TOC were better than that of acid and neutral conditions. The XRD test results showed that the peak position of the sodium aluminate before and after the reaction did not change significantly.
In order to make the best use of oxidants and UV irradiation in dielectric barrier discharge (DBD), catalyst sodium bismuthate was added into a rod-plate DBD reactor. The spectral characteristics of DBD and the effects of pH value, aniline initial concentration, and catalyst dosage on aniline degradation rate were investigated. The synergistic catalytic mechanism of aniline removal was discussed. The results show that the radiation of UV and visible light was produced in the discharge process, and the highest intensity spectral in the range of 300-450 nm is N2 second positive band line. The degradation efficiency of 100 mg/L aniline was improved after sodium bismuthate being added, and total organic carbon (TOC) removal was improved 14.11% with 0.2 g/L catalyst addition. Under alkaline condition, the degradation rates of aniline and TOC were better than that of acid and neutral conditions. The XRD test results showed that the peak position of the sodium aluminate before and after the reaction did not change significantly.
