最新刊期
卷 0 ， 期 0 ， 2020
- 摘要：Background: The twist of bent crystal is a common problem of sagittal focusing monochromators.In Shanghai Synchrotron Radiation Facility(SSRF),one of monochromators has an unfocused beam profile because of crystal twist.Purpose: In order to amend the twist problem and get theoretical understanding for further design optimization,a study on the mechanism of crystal twist has been developed.Methods: Finite Element Analysis(FEA) models considering anisotropic effect of crystal were constructed to study some common factors,i.e.crystal orientation,clamping method,stiffening ribs and asymmetric clamping on the bent crystal profile.Results: The simulation result shows that among those factors,asymmetric clamping is the main reason causing the crystal twist while crystal orientation is also important.Clamping method is a factor that restricts the asymmetric clamping to a certain scale.Conclusions: For optimizing the system,asymmetric clamping should be controlled and crystal should be cut in a particular orientation.关键词：Sagittal focusing monochromator;Bent crystal;Twist of crystal;Finite element analysis
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发布时间：2021-03-05 - 摘要：Background: With the development of high energy physics,high performance of electron linear accelerator is required for large collider,FEL and high brightness synchrotron radiation light source.Structure asymmetry of single coupler destroys the symmetry of field distribution in coupled cavity,which reduces the quality of beam.Purpose: Optimize the asymmetry of field distribution in coupled cavity and improve the quality of beam.Methods: The simulation designs are made for single offset coupler,double symmetry coupler and the new coupler loaded by dielectric rods at X band by using CST microwave studio code.Results: The results show that the distribution of field in coupled cavity is better and all particles almost locate at the center of beam hole after beam passing through the coupler loaded by dielectric rods.The energy spread has also been significantly improved.Conclusions: The coupler loaded by dielectric rods can optimize the asymmetry of field distribution in coupled cavity and improve the quality of beam.关键词：Coupler;Field distribution;Energy spread;Particle beam
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发布时间：2021-03-05 - 摘要：Background: The firing techniques of producing underglaze copper red porcelain emerged in the Yuan dynasty and reached its maturity during the Ming and Qing Dynasties in Jingdezhen city.The technique of producing underglaze red porcelain was sensitive to the firing temperature and atmosphere,so it was very hard to produce and also difficult to display red color under the surface successfully.Purpose & Methods: The micro SR-XRF technique was employed to analysis a piece of sherd of underglaze copper red porcelain of early Ming dynasty.The Chemical compositions of glaze and color areas were presented,and the elemental contents in different color areas were obtained by using line-scanning techniques.Results: Some elements such as As and Pb were contained in raw materials,and the content of Cu had obviously increased with the color changing from gray to red.The results indicated that the nature mineral possibly used as the pigment for underglazed copper red porcelain coloration,and the color appearance also depends on the amount of copper in the pigments contained.Conclusions: This paper presents the advantage of the synchrotron radiation XRF technology and contributes to the science evidences for the Chinese ancient porcelain handcraft research.关键词：Underglaze red;SR-XRF;Line-scan;Coloration mechanism
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发布时间：2021-03-05 - 摘要：Background: For construction of free-electron laser(FEL) apparatus,we designed a high-power solid-state modulator system based on the module of insulated gate bipolar transistor(IGBT) switch.Purpose: To meet the higher performance requirements of linear accelerator microwave power source for the FEL.Methods: The module circuit of the high-power modulator is introduced,as well as the critical auxiliary circuit including protection circuit of IGBT,damping circuit,demagnetization circuit and compensating circuits.Results: The whole modulator system is simulated by using software and the module differences that may occurred.The modulator with inductive adder topology can generate a 130 kV,100 A and 13 MW pulse power.Conclusions: The results show that the inductive adder pulse modulator technology is feasible.关键词：Solid-state modulator;Inductive adder;Cell module;Insulated Gate Bipolar Transistor(IGBT)
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发布时间：2021-03-05 - 摘要：Background: Rotating Gantry is widely used in proton therapy due to its small radiation damage toward the normal tissue around the tumor.Proton therapy gantry optics which plays an important role in rotating gantry is under design in Shanghai Advanced Proton Therapy Facility(APTRON).Purpose: To generate a circular beam profile at iso-center while the gantry rotates with different angles.Methods: Different gantry optics matching techniques are used to calculate the beam optics.These methods include the round-beam method(RBM) or not in the front of vacuum window,and use RBM at iso-center.The simulations of beam profile at iso-center after the beam passing through nozzle and body tissue are carried out with Geant4 software.Results: The beam profile at iso-center can be taken as similar among three cases,and there is slight improvement using RBM.Conclusions: The designed proton therapy gantry optics is intensive to the rotation angle and is applicable for the real application.
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发布时间：2021-03-05 - 摘要：Background: Ramie fiber is a kind of natural polymer material with abundant resources and low price,which has been widely applied in textile.Ramie textiles possess many good qualities,such as air permeability,sweat conductivity and antibacterial ability,but the high crystallinity of ramie fiber gives rise to bad spinning property,small extensibility and low chromaticity which restrict its further application.Purpose: In order to reduce the crystallinity of ramie fiber,the electron beam was directly utilized to irradiate ramie fiber.Methods: Ramie fiber was irradiated by electrons with the irradiation doses from 0 to 2 000 kGy,and the irradiated ramie fiber was characterized by XRD and FT-IR.The crystallinity and the crystallinity index of ramie fiber were analyzed,and the irradiation effect was discussed.Results: The crystallinity and the crystallinity index of ramie fiber decrease with the increasing of irradiation doses and the number of-C O increases with the increasing of irradiation doses.Conclusions: The variation behavior of the crystallinity and the crystallinity index of ramie fiber with electron irradiation dose ranging from 0 to 2 000 kGy is got.It is shown that the crystallinity and the crystallinity index of ramie fiber may be effectively reduced by using electron beams irradiation,but also the required crystallinity of ramie fiber in its application can be achieved by controlling the electron beams irradiation doses.关键词：Ramie fiber;Electron irradiation;Crystallinity
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发布时间：2021-03-05 - 摘要：Background: In electronic LINAC,the magnetron is often used as power source.The output frequency of magnetron always changes with the environment and the frequency difference between the output of magnetron and the frequency of accelerator,which will result in the bad performance of LINAC systems.Purpose: To ensure the performance of the work of entire LINAC system effectively,an automatic frequency control system is necessary.Methods: A phase locked frequency discriminator is designed to discriminate the frequency of accelerator guide and magnetron,and analogue circuit is used to process the output signals of frequency discriminator unit.Results: Working with the automatic frequency control(AFC) system,the output frequency of magnetron can be controlled in the range of(2 998 MHz,2998 MHz+70 kHz) and(2 998 MHz,2 998 MHz-30 kHz).Conclusions: Under the measurement and debug,the functionality of frequency discriminator unit and signal processor circuit is tested effectively.关键词：Frequency discriminate unit;Microwave electronic LINAC;Automatic frequency control(AFC);Signal processing
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发布时间：2021-03-05 - 摘要：Background: The nuclear fuel rod is a key component of nuclear plants and reactors.It works in the extreme conditions,so it is easy to be broken.In order to be safe in operation,lots of testings have to be carried out from fabricating to operating of the fuel rod.Purpose: As a unique non-destructive testing technique,neutron radiography can be used to measure the nuclear fuel rods with radioactivity by an indirect neutron radiography method.Study the indirect neutron radiography method is the primary step of testing.Methods: Non-destructive testing experiments were carried out at China Advanced Research Reactor(CARR) by indirect neutron radiography method with dummy nuclear fuel rods as the samples.The 0.1 mm-thick Dy foil was used as the neutron converter.Results: The neutron images of dummy nuclear fuel rods were obtained.The resolution of testing was analyzed with the images.Through imaging analysis methods,the structure defections,the hydrogen accumulation in the cladding and the U-235 enrichment of pellet were studied and analyzed.Conclusions: The indirect neutron radiography method and the neutron image analysis method were studied.The work described in this paper provides a primary guideline for investigating actual irradiated fuel rods by the neutron radiography at CARR in the future.关键词：Neutron radiography;Nuclear fuel rod;Non-destructive testing;China Advanced Research Reactor(CARR)
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发布时间：2021-03-05 - 摘要：Background: The dose point kernel and the absorbed fraction are essential in the absorbed dose calculation for radionuclide therapy.Purpose: To calculate the scaled dose point kernels for 1 MeV monoenergetic electrons and32P,90Y,131I radionuclides,the absorbed fractions for 0.2 MeV and 4 MeV monoenergetic electrons and 32P,90Y radionuclides which uniformly distributed in water spheres of various mass ranging from 10 2to 103g,and the radial distributions of absorbed dose rates for 32P,131I,90Y nuclides and 15 keV,30 keV,100 keV photons which uniformly distributed in a water(tumor) spherical shell(0.22 r 0.66 cm) with an activity of 1 MBq/cm3.Methods: EGSnrc Monte Carlo programs were used for simulation.Results: The calculation results were compared with those of other works.Conclusions: The results could give some help to absorbed dose calculations for radionuclide therapy.关键词：Radionuclide;Dose point kernel;Absorbed fraction;Monte Carlo
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发布时间：2021-03-05 - 摘要：Background: There are three methods for determination of 210Pb radioactivity concentration in environmental water.One is detecting rays of 210Bi guided by the EJT 859-1994,one is detecting rays of 210Po for 210Pb radioactivity,and the other is using gamma ray spectrometer to determinate the radioactivity of210Pb.But the first method can not give an exact recovery rate of210Pb,the second one is a time-consuming process,and the third one is unable to detect 210Pb in water samples because of its detection limit.This paper describes a method of rapid determination of 210Pb in environmental water with the anion exchange.Purpose: To determine the radioactivity of 210Pb in water samples rapidly.Methods: The stable Pb carrier is added to the water samples for the recovery rate in the chemical and physical process.210Pb and Pb carrier in the water samples are adsorbed and concentrated by Fe(OH)3co-precipitation undergoing heating.210Pb and its carrier are isolated from most interference by an anion exchange.The PbSO4 precipitation has been purified via being precipitated for three times.The PbSO4 precipitation has been stored in the environmental temperature for one month.And then,the rays of 210Bi and the daughter of 210Pb are detected to determine the radioactivity concentration of 210Pb.Results: This method provides a stable and reliable result and costs less time than the method that detects rays of 210Po for 210Pb radioactivity.Conclusions: The method for rapid determination of 210Pb is a practical and reliable method and used to analyze water samples in Yunnan province.关键词：210Pb analysis;Low level radioactivity analysis;Ion exchange;Co-precipitation
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发布时间：2021-03-05 - 摘要：Background: The traditional FPGA program is developed with HDL code,which will cost a lot of time and energy in writing and debugging the underlying code.Purpose: We want to use a new approach to develop FPGA program,which will greatly accelerate the FPGA development.And our system can also be compatible with NI(American National Instrument Company) CRIO case.Methods: We also choose FPGA as the core of hardware and use LabVIEW language(a graphical language) to develop FPGA program.Results: We realized a universal data interface platform by LabVIEW,which is different from the traditional FPGA development process using HDL.This system can provide many functions such as data processing,data IO and implementation of the PCI interface communication.Conclusions: FPGA program can also be developed by LabVIEW language,and it can achieve the corresponding data interface functions,and greatly reduce development time.关键词：LabVIEW;FPGA;PCI9054;DMA
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发布时间：2021-03-05 - 摘要：Background: The on-line low-level liquid radioactivity concentration measurement device is designed for monitoring the radioactivity level of nuclear power plant waste water.The relation between the radioactivity concentration of 137Cs in the liquid of pipeline and the counting rate of measurement device,i.e.the response coefficient is must be known.It is generally given by experimental calibration.But the calibration is difficult for on-line measurement.Purpose: This paper attempts to study the response coefficient of on-line measurement device by calculation.Methods: The response coefficient is calculated by Monte Carlo method and in which γ-ray transport processes in detection device are simulated.The response counts in NaI detector derived from 137Cs in the liquid are calculated.Results: The response coefficient of off-line measuring device is calculated firstly.The result is in good agreement with the experimental calibration and the difference is small than 3%.It is indicated that the method is correct and the calculation model is reasonable.Then,the response coefficient of on-line measuring devices is calculated according to the on-line measurement device design and the structure of NaI detector.The minimum detectable concentration is given according to the response coefficient and the background count rate.Conclusions: The response coefficient of on-line measurement device is 1.249×10 4 s 1 Bq 1 m3 and the minimum detectable concentration can reach(4–5)×103Bq m 3when the thickness of lead shield is 80 mm.关键词：Radioactivity concentration of low-level liquid;Measurement device;Response coefficient;Minimum detectable concentration;Monte Carlo method
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发布时间：2021-03-05 - 摘要：Background: Dynamic atomic force microscopy has become a powerful tool for the nanoscale imaging of biological samples.In solution,the cantilever oscillation parameters such as quality factor and frequency response are critical for stable imaging and precise measurements.The commonly driving cantilever method is acoustical-piezoelectrical approach.However,this indirect excitation mechanism will induce many spurious resonance peaks due to the hydrodynamic interaction between the fluid cell and the liquid in solution,which produce an unstable oscillation of the cantilever.Purpose: Drive the cantilever in a direct way to obtain a well controlled oscillation.Methods: Several direct driving techniques have been successfully developed such as magnetic,electrostatic,acoustical and photothermal excitations.Results: There is a single resonance peak in the cantilever oscillation spectrum under liquid environment with these direct driving methods.Conclusions: Several methods can directly drive the cantilever including magnetic,electrostatic,acoustical and photothermal excitations.The amplitude and frequency response with these different methods is compared.关键词：Atomic Force Microscope;Cantilever oscillation;Magnetic;Electrostatic;Acoustical;Photothermal
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发布时间：2021-03-05 - 摘要：Background: The graphite pebble test section of FLiNaK molten salt high temperature testing loop was designed to study the heat transfer behavior and corrosion behavior between FLiNaK molten salt and fuel pebbles.In graphite pebble test section,the graphite pebbles are heated using a unique medium frequency inductive heating technique to simulate the heat generation inside the fuel pebbles of Pebble Bed Advanced High Temperature Reactor(PB-AHTR).Purpose: The aim is to study the influence of the induction heating by three kinds of graphite pebbles packing scheme.Methods: Numerical simulation of induction heating using finite element method is implemented and the power loss in graphite pebbles is calculated,and then the three kinds of graphite pebbles packing scheme are compared and analyzed from eddy power loss and power distribution.Results: The results show that the relative axial power distributions of three packing schemes are almost the same and the radial power distribution of the packing scheme with no contact between graphite pebbles in each layer is more uniform than that of other packing schemes.Conclusions: In order to heat graphite pebbles evenly and simulate the heat generation inside fuel pebbles of PB-AHTR better,the packing scheme with no contact between graphite pebbles in each layer is recommended.关键词：PB-AHTR;Induction heat;Finite Element Method(FEM);Power loss;FLiNaK
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发布时间：2021-03-05 - 摘要：Background: Edge rotation diagnostic system(ERD) with spatial and temporal resolution has been developed on EAST Tokamak.Purpose: The ERD system is an effective method to research the radiation phenomenon of C,O,Li,N,He and Ar in visible range.The ERD has been used for the measurement of ion temperature and rotation velocity at the edge plasma.Methods: The measurement was done by using an optical fiber spectrometer and two systems of lenses.Results: The ion radiant flux coupled by each fiber can be expressed as an analytical form,and the sightline of each fiber was determinated,and the spectrometer was calibrated by using a halogen lamp.Conclusions: The initial experimental results were obtained by analysing spectral lines of CIII,which results suggest that ERD has the ability to provide edge ion temperature and rotation velocity.关键词：Rotation velocity;Ion temperature;Edge rotation diagnostic(ERD)
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发布时间：2021-03-05
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