In recent years,due to the scarcity of domestic radioisotopes,the Chinese government has strongly supported the development of dedicated radioisotope production facilities.This paper presents conceptual design simulat...In recent years,due to the scarcity of domestic radioisotopes,the Chinese government has strongly supported the development of dedicated radioisotope production facilities.This paper presents conceptual design simulations of an 11 MeV,50μA,H^(-) compact superconducting cyclotron for radioisotope production.This paper focuses primarily on four aspects:magnet system design,central region configuration,beam dynamics analysis,and extraction system design.This paper outlines the cyclotron's primary parameters and key steps in the development process.展开更多
Electron cyclotron emission imaging(ECEI)is a critical diagnostic tool for measuring two-dimensional electron temperature fluctuations.The optical system,a key component of the ECEI diagnostic,determines the spatial r...Electron cyclotron emission imaging(ECEI)is a critical diagnostic tool for measuring two-dimensional electron temperature fluctuations.The optical system,a key component of the ECEI diagnostic,determines the spatial resolution,field of view,and imaging performance of electron temperature fluctuations.In this study,comprehensive laboratory tests and characterizations of the optical system,including the local oscillator(LO)coupling optics and the radio frequency(RF)receiving optics,were conducted to ensure optimal performance during plasma discharge experiments.Laboratory testing of the LO optics revealed that the light intensity at the edge channels reaches 36%of that at the central channels;however,both are sufficient to effectively drive the down-converted mixers.The RF optics focus covers the entire non-harmonic overlap region,corresponding to a normalized plasma minor radius range of ρ=−0.2 to 0.9,and offers three zoom modes:narrow,medium,and wide,with poloidal resolutions of 1.5 cm,1.8 cm,and 2.1 cm,respectively.The characterizations for these zoom modes align well with the optical design specifications.It was observed that the imaging surfaces of all zoom modes are exceptionally flat,indicating high-quality ECEI measurements with excellent spatial resolution.The LO lens,focusing lens,and zoom adjustment lens are capable of remote independent control,which enhances the operational flexibility of the system.Preliminary analyses conducted with the ECEI system successfully captured the two-dimensional structure and spatiotemporal evolution of phenomena such as sawtooth crashes,demonstrating the robust capability of the system to provide valuable insights into plasma dynamics.展开更多
In this paper, a high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform-ion cyclotron resonance mass spectrometry （HPLC-UV/FrICRMS） method was described for the investigation...In this paper, a high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform-ion cyclotron resonance mass spectrometry （HPLC-UV/FrICRMS） method was described for the investigation of impurity profile in moxifloxacin （MOX） drug substance and chemical reference substance. Ten impurities were detected by HPLC-UV, while eight impurities were identified by using the high accurate molecular mass combined with multiple-stage mass spectrometric data and fragmentation rules. In addition, to our knowledge, five impurities were founded for the first time in MOX drug substance.展开更多
The SC200 proton therapy superconducting cyclotron was developed by ASIPP (Hefei, China) and JINR (Dubna, Russia). A measurement system was designed to assess the average radial component of the magnetic field (Brav) ...The SC200 proton therapy superconducting cyclotron was developed by ASIPP (Hefei, China) and JINR (Dubna, Russia). A measurement system was designed to assess the average radial component of the magnetic field (Brav) with 15 search coils in the median plane. The winding differences of the search coils affect the measurement accuracy of the Brav. Based on the electromagnetic induction principle, to measure the Brav accurately, this paper focuses on the design and commissioning of the Brav measurement system. The preliminary results confirm that the system design is reasonable and suitable. After testing the search coil at different speeds, the optimal speed was determined as 2.5 mm/s. The relative error was approximately 0.1% under the maximum radial component of the magnetic field Br of 7 G. The measurement precision was up to 1.0×10^-3, which can provide the required measurement tolerance of 3–7 G for Br in the median plane. The commissioning of the Brav measurement system is an important step for Br measurement. It can check and adjust the asymmetry of the superconducting coils (SCs).展开更多
The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field...The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field and different phonon modes including interface, confined and half-space phonon modes are considered in our calculation. The results for a zinc-blende quantum well are also given for comparison. It is found that the main contribution to the transition energy comes from half-space and interface phonon modes when the well width is very small while the confined modes play a more important role in a wider well due to the location of the electron wave function. As the well width increases, the cyclotron mass of magnetopolarons first increases to a maximum and then decreases either with or without the built-in electric field in the wurtzite structure and the built-in electric field slightly reduces the cyclotron mass. The variation of cyclotron mass in a zinc-blende structure is similar to that in a wurtzite structure. With the increase of external magnetic field, the cyclotron mass of polarons almost linearly increases. The cyclotron frequency of magnetopolarons is also discussed.展开更多
An upgraded electron cyclotron emission imaging （ECEI） system consisting of new optics lenses with necessary electronics for receiving and processing signals for two dimension （2D） ECEI diagnostics was installed o...An upgraded electron cyclotron emission imaging （ECEI） system consisting of new optics lenses with necessary electronics for receiving and processing signals for two dimension （2D） ECEI diagnostics was installed on EAST. Hyperboloid lens were adopted in the new system to optimize the spatial resolutions. The mixers array of sixteen elements measured the plasma electron cyclotron emission at eight frequencies simultaneously, and the profiles of the electron temperature and its fluctuation in an area of 20 cm （vertical） × 6 cm （horizontal） could then be analyzed. Evolution of sawtooth precursor and crash in EAST was observed.展开更多
This paper considers the coupling analysis of phased antenna array designed to excite fast wave in the ion cyclotron range of frequency. The coupling of the antenna is calculated in slab geometry. The coupling code ba...This paper considers the coupling analysis of phased antenna array designed to excite fast wave in the ion cyclotron range of frequency. The coupling of the antenna is calculated in slab geometry. The coupling code based on the variational principle gives the self-consistent current flowing in the antenna, this method has been extended so that it can be applied to a phased antenna array. As an example, this paper analyses the coupling prosperities of a 2 × 2 phased antenna array. It gives the optimum geometry of antenna array. The fields excited at plasma surface are found to more or less correspond to the antenna current phasing.展开更多
For ion cyclotron resonance heating, the current on the antenna surface exists in a form of standing wave, and the phase of the poloidal current standing wave affects significantly on the performance of the coupling. ...For ion cyclotron resonance heating, the current on the antenna surface exists in a form of standing wave, and the phase of the poloidal current standing wave affects significantly on the performance of the coupling. In this paper, a coupling calculation is carried out based on a practical model for the loop antenna. The ion cyclotron wave coupling performance depends greatly on the antenna current propagation constant and the phase of standing wave. For a small antenna-current-propagation constant, the antenna coupling performance is more sensitive to a π/2 change in the phase of standing wave.展开更多
Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion...Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion equation considering both cyclotron resonance and Cherenkov resonance in a staggered double metallic grating traveling wave tube is deduced.Through the reasonable selection for geometric and electrical parameters, the numerical calculation and analysis of the ‘hot’ dispersion equation shows that the beam–wave interaction gain and frequency band with the cyclotron resonance enhancement effect are higher than those with only Cherenkov resonance radiation.展开更多
A fully superconducting electron cyclotron resonance （ECR） ion source （SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconductin...A fully superconducting electron cyclotron resonance （ECR） ion source （SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconducting solenoids （Nb-Ti/Cu） and six superconducting sextupoles （Nb-Ti/Cu）. Different from the conventional supercon- ducting ECR magnetic structure, the SEC17AL Ⅱ includes three superconducting solenoid coils＇ that are located inside the superconducting sextupoles. The SECRAL Ⅱ can significantly reduce the interaction forces between the sextupole and the solenoids, and the magnets can also be more compact in size. For this multi-component SECRAL Ⅱ generating its self field of -8 T and being often exposed to the high self field, the mechanical analysis has become the main issue to keep their stress at 〈200 MPa on coils. The analytical and experimental results in mechanics are presented in the SECRAL Ⅱ structure. To improve the accuracy and efficiency of analysis, according to the composite rule of micromechanics, the equivalent uniform windings are used to simulate the epoxy-impregnated Nb-Ti/Cu coils. In addition, using low temperature strain gauges and a wireless fast strain acquisition system, a fundamental experiment on the based on our analysis, the stresses and deformations optimized. strains developments of a sextupole is reported. Finally, for its assembly of each SECRAL Ⅱ coil will be further展开更多
During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. ...During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors： electroh cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.展开更多
The optimized synergy conditions between electron cyclotron current drive （ECCD） and lower hybrid current drive （LHCD） with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on th...The optimized synergy conditions between electron cyclotron current drive （ECCD） and lower hybrid current drive （LHCD） with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on the under- standing of the synergy mechanisms so as to obtain a higher synergistic current and provide theoretical reference for the synergistic effect in the EAST experiment. The dependences of the synergistic effect on the parameters of two waves （lower hybrid wave （LHW） and electron cyclotron wave （ECW））, including the radial position of the power deposition, the power value of the LH and EC waves, and the parallel refractive indices of the LHW （Nr） are oresented and discussed.展开更多
With one-dimensional （l-D） hybrid simulations we investigate the nonlinear evolu- tion of the ion cyclotron waves excited by the H＋ and He2＋ temperature anisotropies, and analyze the evolution by using the wavelet...With one-dimensional （l-D） hybrid simulations we investigate the nonlinear evolu- tion of the ion cyclotron waves excited by the H＋ and He2＋ temperature anisotropies, and analyze the evolution by using the wavelet analysis method. The results show that the proton cyclotron waves with the dominant frequency higher than the helium gyro-frequency （ΩHe = 0.5Ωp, with Ωp and ΩHe the proton and helium gyro-frequencies respectively ） are firstly excited, and then the helium cyclotron waves with the dominant frequency lower than the helium gyro-frequency are excited. The relation of our simulation results to the BIF（bifurcated） （there are two peaks in the wave spectrum： one above and one below ΩHe） and CON（continuous） （continuous spectrum from 0.1 Ωp to 1.0 Ωp） wave spectra observed in the magnetosheath are discussed.展开更多
A number of simulations of electron cyclotron current drive (ECCD) have been carried out for the China Fusion Engineering Test Reactor (CFETR) using the C3PO/LUKE code to investigate the performance and optimize schem...A number of simulations of electron cyclotron current drive (ECCD) have been carried out for the China Fusion Engineering Test Reactor (CFETR) using the C3PO/LUKE code to investigate the performance and optimize schemes of power injection for the design of the launcher.The operation ranges of the toroidal field,cutoff density,and resonance layer location are given at different source frequencies in CFETR phases Ⅰ and Ⅱ.A comparison of ECCD performance between the horizontal and top port launch is presented.ECCD efficiency (γEC) estimated for CFETR phase Ⅰ is γEC =0.21 for top port launch and γEC =0.20 for horizontal port launch.The ECCD efficiency and second-harmonic absorption is calculated at different wave frequencies (from 170 to 230 GHz) in CFETR phase Ⅱ.It is found that the highest driven efficiency is obtained at 210 GHz with the toroidal field of 6.5 T,and the second-harmonic absorption increases rapidly with the increase of frequency.展开更多
Proton cyclotron waves(PCWs)can be generated by ion pickup of Martian exospheric particles in the solar wind.The solar wind ion pickup process is highly dependent on the“IMF cone angle”—the angle between the solar ...Proton cyclotron waves(PCWs)can be generated by ion pickup of Martian exospheric particles in the solar wind.The solar wind ion pickup process is highly dependent on the“IMF cone angle”—the angle between the solar wind velocity and the interplanetary magnetic field(IMF),which also plays an important role in the generation of PCWs.Using data from 2.15 Martian years of magnetic field measurements collected by the Mars Atmosphere and Volatile Evolution(MAVEN)mission,we have identified 3307 upstream PCW events.Their event number distribution decreases exponentially with their duration.A statistical investigation of the effects of IMF cone angle on the amplitudes and occurrence rates of PCWs reveals a slight tendency of PCWs’amplitudes to decrease with increasing IMF cone angle.The relationship between the amplitude and IMF cone angle is weak,with a correlation coefficient r=–0.3.We also investigated the influence of IMF cone angle on the occurrence rate of PCWs and found that their occurrence rate is particularly high for intermediate IMF cone angles(~18°–42°)even though highly oblique IMF orientation occurs most frequently in the upstream region of the Martian bow shock.We also conclude that these variabilities are not artefacts of temporal coverage biases in MAVEN sampling.Our results demonstrate that whereas IMF cone angle strongly influences the occurrence of PCWs,IMF cone angle may also weakly modulate their amplitudes in the upstream region of Mars.展开更多
A rapid and sensitive method for analyzing trace b-blockers in complex biological samples,which involved magnetic solid-phase extraction(MSPE)coupled with Fourier transform ion cyclotron resonance mass spectrometry(FT...A rapid and sensitive method for analyzing trace b-blockers in complex biological samples,which involved magnetic solid-phase extraction(MSPE)coupled with Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS),was developed.Novel nanosilver-functionalized magnetic nanoparticles with an interlayer of poly(3,4-dihydroxyphenylalanine)(polyDOPA@Ag-MNPs)were synthesized and used as MSPE adsorbents to extract trace b-blockers from biological samples.After extraction,the analytes loaded on the polyDOPA@Ag-MNPs were desorbed using an organic solvent and analyzed by FTICR-MS.The method was rapid and sensitive,with a total detection procedure of less than 10 min as well as limits of detection and quantification in the ranges of 3.5-6.8 pg/mL and 11.7-22.8 pg/mL,respectively.The accuracy of the method was also desirable,with recoveries ranging from 80.9%to 91.0%following the detection of analytes in human blood samples.All the experimental results demonstrated that the developed MSPE-FTICR-MS method was suitable for the rapid and sensitive analysis of trace b-blockers in complex biological samples.展开更多
Electromagnetic ion cyclotron(EMIC)waves are widely believed to play an important role in influencing the radiation belt and ring current dynamics.Most studies have investigated the effects or characteristics of EMIC ...Electromagnetic ion cyclotron(EMIC)waves are widely believed to play an important role in influencing the radiation belt and ring current dynamics.Most studies have investigated the effects or characteristics of EMIC waves by assuming their left-handed polarization.However,recent studies have found that the reversal of polarization,which occurs at higher latitudes along the wave propagation path,can change the wave-induced pitch angle diffusion coefficients.Whether such a polarization reversal can influence the global ring current dynamics remains unknown.In this study,we investigate the ring current dynamics and proton precipitation loss in association with polarization-reversed EMIC waves by using the ring current-atmosphere interactions model(RAM).The results indicate that the polarization reversal of H-band EMIC waves can truly decrease the scattering rates of protons of 10 to 50 keV or>100 keV in comparison with the scenario in which the EMIC waves are considered purely left-handed polarized.Additionally,the global ring current intensity and proton precipitation may be slightly affected by the polarization reversal,especially during prestorm time and the recovery phase,but the effects are not large during the main phase.This is probably because the H-band EMIC waves contribute to the proton scattering loss primarily at E<10 keV,an energy range that is not strongly affected by the polarization reversal.展开更多
The transmission of science and technology from the Soviet Union to People’s Republic of China in the mid-twentieth century is an important research area of contemporary history of science and technology.This paper t...The transmission of science and technology from the Soviet Union to People’s Republic of China in the mid-twentieth century is an important research area of contemporary history of science and technology.This paper takes the construction of the cyclotron in Lanzhou,China as the case to discuss the characteristics of technology transfer from the Soviet Union to China.The review of extensive archives reveals that the construction of cyclotron took place in the framework of China’s nuclear weapons development.Although the transmission of science and technology from the Soviet Union to China fit into the one-way transmission-reception model in general,both the Chinese demand and the Soviet response had key influences on the transmission.In the early cyclotron construction,the Chinese side relied on the Soviets,and the mode of the cooperation between Soviet and Chinese engineers can be described as one of expertstudent.In the early 1960 s,the relationship between China and the Soviet Union broke down.The Soviet engineers were required to withdraw with the technical data,which created conflicts in the roles played by the Soviet engineers,most of whom chose to set the sense of professional responsibility as their highest priority.After the departure of the Soviet experts,Chinese physicists played the leading role in the project,using scientific knowledge they had,relying on the technical materials left by Soviet experts,and cooperating fully with local engineers,thus completing the cyclotron.This case can provide us with valuable clues for the understanding of transnational history of science and technology.The seemingly one-way transmission-reception model is actually influenced by the needs of both sides.While the transnational flow of knowledge is inevitably affected by political factors from both sides,the process is far more complex than it appears.展开更多
The superconducting cyclotron SC200 is intended to generate a 200 MeV, 400 nA proton beam for future particle therapy. The internal hot-cathode-type Penning ionization gauge (PIG) ion source for the SC200 is designed ...The superconducting cyclotron SC200 is intended to generate a 200 MeV, 400 nA proton beam for future particle therapy. The internal hot-cathode-type Penning ionization gauge (PIG) ion source for the SC200 is designed for the generation of hydrogen ions. A brief description of the design of ion source and test bench, which are used in SC200, is given in this paper. The ion source has been verified on the test bench, and the results indicated that the designed ion source meets the expected requirements. The lifetime of the filament exceeded 100 h in the test. In addition, the extraction voltage and the gas flow that influence the extracted ion current intensity have been tested in the experiment.展开更多
Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating （ECRH） system of the HL-2A tokamak are presented. The calculation is based on...Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating （ECRH） system of the HL-2A tokamak are presented. The calculation is based on an integral method developed in the vector theory of diffraction gratings, and the polarization characteristics obtained with a low-power test are in good agreement with the numerical calculated results. With the polarizer assembled in a miter bend in the ECRH transmission line, pure ordinary mode （O-mode） and extraordinary mode （X-mode） polarized waves are also expected in the high-power experiment, depending on the polarizer rotation angle and the toroidal injection angle of the electron cyclotron （EC） wave beam. Second-harmonic X-mode experiments were successfully explored in HL-2A. Experimental result revealed that the electron temperature increased from 0.8 keV （Ohmic heating phase） to 1.5 keV （second X-mode heating phase）.展开更多
文摘In recent years,due to the scarcity of domestic radioisotopes,the Chinese government has strongly supported the development of dedicated radioisotope production facilities.This paper presents conceptual design simulations of an 11 MeV,50μA,H^(-) compact superconducting cyclotron for radioisotope production.This paper focuses primarily on four aspects:magnet system design,central region configuration,beam dynamics analysis,and extraction system design.This paper outlines the cyclotron's primary parameters and key steps in the development process.
基金partly supported by the National MCF Energy R&D Program of China(No.2022YFE03060003)partly by the Chinese National Fusion Project for ITER(No.2024YFE03190000)+2 种基金partly by National Natural Science Foundation of China(No.12405254)partly by the Innovation Program of Southwestern Institute of Physics(No.202301XWCX001-02)partly by Sichuan Science and Technology Program(No.2023ZYD0014).
文摘Electron cyclotron emission imaging(ECEI)is a critical diagnostic tool for measuring two-dimensional electron temperature fluctuations.The optical system,a key component of the ECEI diagnostic,determines the spatial resolution,field of view,and imaging performance of electron temperature fluctuations.In this study,comprehensive laboratory tests and characterizations of the optical system,including the local oscillator(LO)coupling optics and the radio frequency(RF)receiving optics,were conducted to ensure optimal performance during plasma discharge experiments.Laboratory testing of the LO optics revealed that the light intensity at the edge channels reaches 36%of that at the central channels;however,both are sufficient to effectively drive the down-converted mixers.The RF optics focus covers the entire non-harmonic overlap region,corresponding to a normalized plasma minor radius range of ρ=−0.2 to 0.9,and offers three zoom modes:narrow,medium,and wide,with poloidal resolutions of 1.5 cm,1.8 cm,and 2.1 cm,respectively.The characterizations for these zoom modes align well with the optical design specifications.It was observed that the imaging surfaces of all zoom modes are exceptionally flat,indicating high-quality ECEI measurements with excellent spatial resolution.The LO lens,focusing lens,and zoom adjustment lens are capable of remote independent control,which enhances the operational flexibility of the system.Preliminary analyses conducted with the ECEI system successfully captured the two-dimensional structure and spatiotemporal evolution of phenomena such as sawtooth crashes,demonstrating the robust capability of the system to provide valuable insights into plasma dynamics.
基金the Ministry of Public Health of the People's Republic of China(No200802038) for financial support
文摘In this paper, a high-performance liquid chromatography coupled with ultraviolet detection and Fourier transform-ion cyclotron resonance mass spectrometry （HPLC-UV/FrICRMS） method was described for the investigation of impurity profile in moxifloxacin （MOX） drug substance and chemical reference substance. Ten impurities were detected by HPLC-UV, while eight impurities were identified by using the high accurate molecular mass combined with multiple-stage mass spectrometric data and fragmentation rules. In addition, to our knowledge, five impurities were founded for the first time in MOX drug substance.
基金supported by the Natural Science Foundation of Anhui under Grant(No.1908085QA25)the Research Initiation Foundation of Anhui Polytechnic University(No.2018YQQ001)+3 种基金the PreResearch National Natural Science Foundation of China of Anhui Polytechnic University(No.2019yyzr13)the National Natural Science Foundation of China(Nos.11575237 and 11775258)the National Magnetic Confinement Fusion Science Program(No.2015GB101001)the International Scientific and Technological Cooperation Project of Anhui(No.1704e1002207)
文摘The SC200 proton therapy superconducting cyclotron was developed by ASIPP (Hefei, China) and JINR (Dubna, Russia). A measurement system was designed to assess the average radial component of the magnetic field (Brav) with 15 search coils in the median plane. The winding differences of the search coils affect the measurement accuracy of the Brav. Based on the electromagnetic induction principle, to measure the Brav accurately, this paper focuses on the design and commissioning of the Brav measurement system. The preliminary results confirm that the system design is reasonable and suitable. After testing the search coil at different speeds, the optimal speed was determined as 2.5 mm/s. The relative error was approximately 0.1% under the maximum radial component of the magnetic field Br of 7 G. The measurement precision was up to 1.0×10^-3, which can provide the required measurement tolerance of 3–7 G for Br in the median plane. The commissioning of the Brav measurement system is an important step for Br measurement. It can check and adjust the asymmetry of the superconducting coils (SCs).
基金Project supported by the National Natural Science Foundation of China (Grant No. 10964007)the Natural Science Foundation of Inner Mongolia,China (Grant No. 2009MS0110)
文摘The cyclotron mass of magnetopolarons in wurtzite InxGa1-xN/GaN quantum well is studied in the presence of an external magnetic field by using the Larsen perturbation method. The effects of the built-in electric field and different phonon modes including interface, confined and half-space phonon modes are considered in our calculation. The results for a zinc-blende quantum well are also given for comparison. It is found that the main contribution to the transition energy comes from half-space and interface phonon modes when the well width is very small while the confined modes play a more important role in a wider well due to the location of the electron wave function. As the well width increases, the cyclotron mass of magnetopolarons first increases to a maximum and then decreases either with or without the built-in electric field in the wurtzite structure and the built-in electric field slightly reduces the cyclotron mass. The variation of cyclotron mass in a zinc-blende structure is similar to that in a wurtzite structure. With the increase of external magnetic field, the cyclotron mass of polarons almost linearly increases. The cyclotron frequency of magnetopolarons is also discussed.
基金supported by the National Basic Research Program of China (No. 2008CB717800)National Natural Science Foundation of China (No. 10335060)+2 种基金Grants from the Ministry of Education and the Chinese Academy of SciencesCAS-JSPS Core University Program in Plasma and Nuclear Fusionby the PRC-US Fusion Cooperation Program (Plasma Physics, Project A-5)
文摘An upgraded electron cyclotron emission imaging （ECEI） system consisting of new optics lenses with necessary electronics for receiving and processing signals for two dimension （2D） ECEI diagnostics was installed on EAST. Hyperboloid lens were adopted in the new system to optimize the spatial resolutions. The mixers array of sixteen elements measured the plasma electron cyclotron emission at eight frequencies simultaneously, and the profiles of the electron temperature and its fluctuation in an area of 20 cm （vertical） × 6 cm （horizontal） could then be analyzed. Evolution of sawtooth precursor and crash in EAST was observed.
文摘This paper considers the coupling analysis of phased antenna array designed to excite fast wave in the ion cyclotron range of frequency. The coupling of the antenna is calculated in slab geometry. The coupling code based on the variational principle gives the self-consistent current flowing in the antenna, this method has been extended so that it can be applied to a phased antenna array. As an example, this paper analyses the coupling prosperities of a 2 × 2 phased antenna array. It gives the optimum geometry of antenna array. The fields excited at plasma surface are found to more or less correspond to the antenna current phasing.
文摘For ion cyclotron resonance heating, the current on the antenna surface exists in a form of standing wave, and the phase of the poloidal current standing wave affects significantly on the performance of the coupling. In this paper, a coupling calculation is carried out based on a practical model for the loop antenna. The ion cyclotron wave coupling performance depends greatly on the antenna current propagation constant and the phase of standing wave. For a small antenna-current-propagation constant, the antenna coupling performance is more sensitive to a π/2 change in the phase of standing wave.
基金supported by National Natural Science Foundation of China(No.61671431)
文摘Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion equation considering both cyclotron resonance and Cherenkov resonance in a staggered double metallic grating traveling wave tube is deduced.Through the reasonable selection for geometric and electrical parameters, the numerical calculation and analysis of the ‘hot’ dispersion equation shows that the beam–wave interaction gain and frequency band with the cyclotron resonance enhancement effect are higher than those with only Cherenkov resonance radiation.
基金Supported by the National Natural Science Foundation of China under Grant No 11302225the China Postdoctoral Science Foundation under Grant Nos 2014M560820 and 2015T81071
文摘A fully superconducting electron cyclotron resonance （ECR） ion source （SECRAL ID is currently being built in the Institute of Modern Physics, Chinese Academy of Sciences. Its key components are three superconducting solenoids （Nb-Ti/Cu） and six superconducting sextupoles （Nb-Ti/Cu）. Different from the conventional supercon- ducting ECR magnetic structure, the SEC17AL Ⅱ includes three superconducting solenoid coils＇ that are located inside the superconducting sextupoles. The SECRAL Ⅱ can significantly reduce the interaction forces between the sextupole and the solenoids, and the magnets can also be more compact in size. For this multi-component SECRAL Ⅱ generating its self field of -8 T and being often exposed to the high self field, the mechanical analysis has become the main issue to keep their stress at 〈200 MPa on coils. The analytical and experimental results in mechanics are presented in the SECRAL Ⅱ structure. To improve the accuracy and efficiency of analysis, according to the composite rule of micromechanics, the equivalent uniform windings are used to simulate the epoxy-impregnated Nb-Ti/Cu coils. In addition, using low temperature strain gauges and a wireless fast strain acquisition system, a fundamental experiment on the based on our analysis, the stresses and deformations optimized. strains developments of a sextupole is reported. Finally, for its assembly of each SECRAL Ⅱ coil will be further
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10675124,10775041 and 10775045)
文摘During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors： electroh cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Grant Nos.2011GB102000,2012GB103000,2013GB106001,and2015GB102003)the National Natural Science Foundation of China(Grant Nos.11175206 and 11305211)+1 种基金the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(Grant No.11261140328)the Fundamental Research Funds for the Central Universities of China(Grant No.JZ2015HGBZ0472)
文摘The optimized synergy conditions between electron cyclotron current drive （ECCD） and lower hybrid current drive （LHCD） with normal parameters of the EAST tokamak are studied by using the C3PO/LUKE code based on the under- standing of the synergy mechanisms so as to obtain a higher synergistic current and provide theoretical reference for the synergistic effect in the EAST experiment. The dependences of the synergistic effect on the parameters of two waves （lower hybrid wave （LHW） and electron cyclotron wave （ECW））, including the radial position of the power deposition, the power value of the LH and EC waves, and the parallel refractive indices of the LHW （Nr） are oresented and discussed.
基金supported by National Natural Science Foundation of China (Nos.40725013,40674093)the Open Research Program Foundation of State Key Laboratory for Space Weather,Chinese Academy Sciences
文摘With one-dimensional （l-D） hybrid simulations we investigate the nonlinear evolu- tion of the ion cyclotron waves excited by the H＋ and He2＋ temperature anisotropies, and analyze the evolution by using the wavelet analysis method. The results show that the proton cyclotron waves with the dominant frequency higher than the helium gyro-frequency （ΩHe = 0.5Ωp, with Ωp and ΩHe the proton and helium gyro-frequencies respectively ） are firstly excited, and then the helium cyclotron waves with the dominant frequency lower than the helium gyro-frequency are excited. The relation of our simulation results to the BIF（bifurcated） （there are two peaks in the wave spectrum： one above and one below ΩHe） and CON（continuous） （continuous spectrum from 0.1 Ωp to 1.0 Ωp） wave spectra observed in the magnetosheath are discussed.
基金National Key R&D Program of China (Nos. 2016YFA0400600, 2016YFA0400602, 2016YFA0400603, 2017YFE0300500 and 2017YFE0300503)the National Magnetic Confinement Fusion Science Program of China (No. 2015GB102003)the National Natural Science Foundation of China (Nos. 11675214, 11775259).
文摘A number of simulations of electron cyclotron current drive (ECCD) have been carried out for the China Fusion Engineering Test Reactor (CFETR) using the C3PO/LUKE code to investigate the performance and optimize schemes of power injection for the design of the launcher.The operation ranges of the toroidal field,cutoff density,and resonance layer location are given at different source frequencies in CFETR phases Ⅰ and Ⅱ.A comparison of ECCD performance between the horizontal and top port launch is presented.ECCD efficiency (γEC) estimated for CFETR phase Ⅰ is γEC =0.21 for top port launch and γEC =0.20 for horizontal port launch.The ECCD efficiency and second-harmonic absorption is calculated at different wave frequencies (from 170 to 230 GHz) in CFETR phase Ⅱ.It is found that the highest driven efficiency is obtained at 210 GHz with the toroidal field of 6.5 T,and the second-harmonic absorption increases rapidly with the increase of frequency.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDA17010201)supported by Thousand Young Talents Program of China and Chinese NSFC grant (41525016, 41474155, 41661164034, 41621004, 41374180, 41774188)+1 种基金cofunded by EU. Asupported by the Fund for Scientific Research (F.R.S.FNRS)
文摘Proton cyclotron waves(PCWs)can be generated by ion pickup of Martian exospheric particles in the solar wind.The solar wind ion pickup process is highly dependent on the“IMF cone angle”—the angle between the solar wind velocity and the interplanetary magnetic field(IMF),which also plays an important role in the generation of PCWs.Using data from 2.15 Martian years of magnetic field measurements collected by the Mars Atmosphere and Volatile Evolution(MAVEN)mission,we have identified 3307 upstream PCW events.Their event number distribution decreases exponentially with their duration.A statistical investigation of the effects of IMF cone angle on the amplitudes and occurrence rates of PCWs reveals a slight tendency of PCWs’amplitudes to decrease with increasing IMF cone angle.The relationship between the amplitude and IMF cone angle is weak,with a correlation coefficient r=–0.3.We also investigated the influence of IMF cone angle on the occurrence rate of PCWs and found that their occurrence rate is particularly high for intermediate IMF cone angles(~18°–42°)even though highly oblique IMF orientation occurs most frequently in the upstream region of the Martian bow shock.We also conclude that these variabilities are not artefacts of temporal coverage biases in MAVEN sampling.Our results demonstrate that whereas IMF cone angle strongly influences the occurrence of PCWs,IMF cone angle may also weakly modulate their amplitudes in the upstream region of Mars.
基金supported by the National Natural Science Foundation of China(Grant Nos.:21976168,22127810,and 22004113)Key Research and Development Program of Guangdong Province(Grant No.:2020B1111350002)+1 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.:2019A1515110420)GDAS0 Project of Science and Technology Development(Grant No.:2021GDASYL-20210103034).
文摘A rapid and sensitive method for analyzing trace b-blockers in complex biological samples,which involved magnetic solid-phase extraction(MSPE)coupled with Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS),was developed.Novel nanosilver-functionalized magnetic nanoparticles with an interlayer of poly(3,4-dihydroxyphenylalanine)(polyDOPA@Ag-MNPs)were synthesized and used as MSPE adsorbents to extract trace b-blockers from biological samples.After extraction,the analytes loaded on the polyDOPA@Ag-MNPs were desorbed using an organic solvent and analyzed by FTICR-MS.The method was rapid and sensitive,with a total detection procedure of less than 10 min as well as limits of detection and quantification in the ranges of 3.5-6.8 pg/mL and 11.7-22.8 pg/mL,respectively.The accuracy of the method was also desirable,with recoveries ranging from 80.9%to 91.0%following the detection of analytes in human blood samples.All the experimental results demonstrated that the developed MSPE-FTICR-MS method was suitable for the rapid and sensitive analysis of trace b-blockers in complex biological samples.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41974192 and 41821003)Work at Los Alamos was performed under the auspices of the U.S.Department of Energy(Contract No.89233218CNA000001)was partially funded by an NSF grant(Grant No.IAA2027951).
文摘Electromagnetic ion cyclotron(EMIC)waves are widely believed to play an important role in influencing the radiation belt and ring current dynamics.Most studies have investigated the effects or characteristics of EMIC waves by assuming their left-handed polarization.However,recent studies have found that the reversal of polarization,which occurs at higher latitudes along the wave propagation path,can change the wave-induced pitch angle diffusion coefficients.Whether such a polarization reversal can influence the global ring current dynamics remains unknown.In this study,we investigate the ring current dynamics and proton precipitation loss in association with polarization-reversed EMIC waves by using the ring current-atmosphere interactions model(RAM).The results indicate that the polarization reversal of H-band EMIC waves can truly decrease the scattering rates of protons of 10 to 50 keV or>100 keV in comparison with the scenario in which the EMIC waves are considered purely left-handed polarized.Additionally,the global ring current intensity and proton precipitation may be slightly affected by the polarization reversal,especially during prestorm time and the recovery phase,but the effects are not large during the main phase.This is probably because the H-band EMIC waves contribute to the proton scattering loss primarily at E<10 keV,an energy range that is not strongly affected by the polarization reversal.
基金supported by one of the projects of the National 14th Five-Year Plan:“Compilation of the Volume on History of Science and Technology of the New General History of China”(《(新编)中国通史》科学技术史卷)。
文摘The transmission of science and technology from the Soviet Union to People’s Republic of China in the mid-twentieth century is an important research area of contemporary history of science and technology.This paper takes the construction of the cyclotron in Lanzhou,China as the case to discuss the characteristics of technology transfer from the Soviet Union to China.The review of extensive archives reveals that the construction of cyclotron took place in the framework of China’s nuclear weapons development.Although the transmission of science and technology from the Soviet Union to China fit into the one-way transmission-reception model in general,both the Chinese demand and the Soviet response had key influences on the transmission.In the early cyclotron construction,the Chinese side relied on the Soviets,and the mode of the cooperation between Soviet and Chinese engineers can be described as one of expertstudent.In the early 1960 s,the relationship between China and the Soviet Union broke down.The Soviet engineers were required to withdraw with the technical data,which created conflicts in the roles played by the Soviet engineers,most of whom chose to set the sense of professional responsibility as their highest priority.After the departure of the Soviet experts,Chinese physicists played the leading role in the project,using scientific knowledge they had,relying on the technical materials left by Soviet experts,and cooperating fully with local engineers,thus completing the cyclotron.This case can provide us with valuable clues for the understanding of transnational history of science and technology.The seemingly one-way transmission-reception model is actually influenced by the needs of both sides.While the transnational flow of knowledge is inevitably affected by political factors from both sides,the process is far more complex than it appears.
基金supported by the National Natural Science Foundation of China(Nos.11775258 and 11575237)the International Scientific and Technological Cooperation Project of Anhui(No.1704e1002207)+2 种基金the Research Initiation Foundation of Anhui Polytechnic University(No.2018YQQ001)the Pre-Research National Natural Science Foundation of China of Anhui Polytechnic University(No.2019yyzr13)the Natural Science Foundation of Anhui(No.1908085QA25)
文摘The superconducting cyclotron SC200 is intended to generate a 200 MeV, 400 nA proton beam for future particle therapy. The internal hot-cathode-type Penning ionization gauge (PIG) ion source for the SC200 is designed for the generation of hydrogen ions. A brief description of the design of ion source and test bench, which are used in SC200, is given in this paper. The ion source has been verified on the test bench, and the results indicated that the designed ion source meets the expected requirements. The lifetime of the filament exceeded 100 h in the test. In addition, the extraction voltage and the gas flow that influence the extracted ion current intensity have been tested in the experiment.
文摘Theoretical calculation and experimental results for a polarizer with sinusoidal grooves used in the electron cyclotron resonance heating （ECRH） system of the HL-2A tokamak are presented. The calculation is based on an integral method developed in the vector theory of diffraction gratings, and the polarization characteristics obtained with a low-power test are in good agreement with the numerical calculated results. With the polarizer assembled in a miter bend in the ECRH transmission line, pure ordinary mode （O-mode） and extraordinary mode （X-mode） polarized waves are also expected in the high-power experiment, depending on the polarizer rotation angle and the toroidal injection angle of the electron cyclotron （EC） wave beam. Second-harmonic X-mode experiments were successfully explored in HL-2A. Experimental result revealed that the electron temperature increased from 0.8 keV （Ohmic heating phase） to 1.5 keV （second X-mode heating phase）.
