According to the physics of tokamak start-up,this study constructs a zero-dimensional(0D)model applicable to electron cyclotron(EC)wave assisted start-up in NCST spherical torus(spherical tokamak)and CN-H1 stellarator...According to the physics of tokamak start-up,this study constructs a zero-dimensional(0D)model applicable to electron cyclotron(EC)wave assisted start-up in NCST spherical torus(spherical tokamak)and CN-H1 stellarators.Using the constructed 0D model,the results obtained in this study under the same conditions are compared and validated against reference results for pure hydrogen plasma start-up in tokamak.The results are in good agreement,especially regarding electron temperature,ion temperature and plasma current.In the presence of finite Ohmic electric field in the spherical tokamak,a study on the EC wave assisted start-up of the NCST plasma at frequency of 28 GHz is conducted.The impact of the vertical magnetic field B_(v)on EC wave assisted start-up,the relationship between EC wave injection power P_(inj),Ohmic electric field E,and initial hydrogen atom density n_(H0)are explored separately.It is found that under conditions of Ohmic electric field lower than ITER(~0.3 V m^(-1)),EC wave can expand the operational space to achieve better plasma parameters.Simulating the process of28 GHz EC wave start-up in the CN-H1 stellarator plasma,the plasma current in the zerodimensional model is replaced with the current in the poloidal coil of the stellarator.Plasma startup can be successfully achieved at injection powers in the hundreds of kilowatts range,resulting in electron densities on the order of 10^(17)-10^(18)m^(-3).展开更多
Through theoretical analysis,we construct a physical model that includes the influence of counter-external driven current opposite to the plasma current direction in the neoclassical tearing mode(NTM).The equation is ...Through theoretical analysis,we construct a physical model that includes the influence of counter-external driven current opposite to the plasma current direction in the neoclassical tearing mode(NTM).The equation is used with this model to obtain the modified Rutherford equation with co-current and counter-current contributions.Consistent with the reported experimental results,numerical simulations have shown that the localized counter external current can only partially suppress NTM when it is far from the resonant magnetic surface.Under some circumstances,the Ohkawa mechanism dominated current drive(OKCD)by electron cyclotron waves can concurrently create both co-current and counter-current.In this instance,the minimal electron cyclotron wave power that suppresses a particular NTM was calculated by the Rutherford equation.The result is marginally less than when taking co-current alone into consideration.As a result,to suppress NTM using OKCD,one only needs to align the co-current with a greater OKCD peak well with the resonant magnetic surface.The effect of its lower counter-current does not need to be considered because the location of the counter-current deviates greatly from the resonant magnetic surface.展开更多
Anomalous ion heat transport is analyzed in the T-10 tokamak plasma heated with electron cyclotron resonance heating(ECRH) in second-harmonic extra-ordinary mode. Predictive modeling with empirical scaling for Ohmical...Anomalous ion heat transport is analyzed in the T-10 tokamak plasma heated with electron cyclotron resonance heating(ECRH) in second-harmonic extra-ordinary mode. Predictive modeling with empirical scaling for Ohmical heat conductivity shows that in ECRH plasmas the calculated ion temperature could be overestimated, so an increase of anomalous ion heat transport is required. To study this effect two scans are presented: over the EC resonance position and over the ECRH power. The EC resonance position varies from the high-field side to the low-field side by variation of the toroidal magnetic field. The scan over the heating power is presented with on-axis and mixed ECRH regimes. Discharges with high anomalous ion heat transport are obtained in all considered regimes. In these discharges the power balance ion heat conductivity exceeds the neoclassical level by up to 10 times. The high ion heat transport regimes are distinguished by three parameters: the ratio Te/Ti, the normalized electron density gradient R/■, and the ion–ion collisionality νii~*. The combination of high Te/Ti, high νii~*, and R/■=6-10 results in values of normalized anomalous ion heat fluxes up to 10 times higher than in the low transport scenario.展开更多
This paper describes the experimental analysis and preliminary investigation of the predictability of pitch angle scattering(PAS) events through the electron cyclotron emission(ECE)radiometer signals at the ADITYA-Upg...This paper describes the experimental analysis and preliminary investigation of the predictability of pitch angle scattering(PAS) events through the electron cyclotron emission(ECE)radiometer signals at the ADITYA-Upgrade(ADITYA-U) tokamak. For low-density discharges at ADITYA-U, a sudden abnormal rise is observed in the ECE signature while other plasma parameters are unchanged. Investigations are done to understand this abrupt rise that is expected to occur due to PAS. The rise time is as fast as 100 μs with a single step and/or multiple step rise in ECE radiometer measurements. This event is known to limit the on-axis energy of runaway electrons. Being a repetitive event, the conditions of its repetitive occurrence can be investigated, thereby exploring the possibility of it being triggered and surveyed as an alternate runaway electron mitigation plan. Functional parameterization of such events with other discharge parameters is obtained and the possibility to trigger these events is discussed.PREDICT code is used to investigate the possible interpretations for the PAS occurrence through modeling and supporting the ECE observations. The trigger values so obtained experimentally are set as input criteria for PAS occurrence. Preliminary modeling investigations provide reliable consistency with the findings.展开更多
The electron cyclotron emission(ECE)diagnostic system has been developed on the ENN spherical torus(EXL-50).The ECE system is designed to detect radiation emitted by energetic electrons,rather than conventional 1D ele...The electron cyclotron emission(ECE)diagnostic system has been developed on the ENN spherical torus(EXL-50).The ECE system is designed to detect radiation emitted by energetic electrons,rather than conventional 1D electron temperature profile measurement,in the frequency range of 4-40 GHz.The system is composed of five subsystems,each covering a different frequency band,including the C-band(4-8 GHz),X-band(8-12 GHz),Ku-band(12-18 GHz),K-band(18-26.5 GHz)and Kα-band(26.4-40 GHz).The system uses heterodyne detection to analyze the received signals.The K-band and Kα-band subsystems are located horizontally in the equatorial plane of the EXL-50,while the C-band,X-band and Ku-band subsystems are located under the vacuum vessel of the EXL-50.To direct the microwaves from the plasma to the antennas for the horizontal detection subsystems,a quasi-optical system has been developed.For the vertical detection subsystems,the antennas are directly attached to the port located beneath the torus at R=700 mm,which is also the magnetic axis of the torus.The system integration,bench testing and initial experimental results will be thoroughly discussed,providing a comprehensive understanding of the ECE system s performance and capabilities.展开更多
This study investigates the single-pass absorption(SPA) of ion cyclotron range of frequency(ICRF) heating in hydrogen plasma of the EXL-50U spherical tokamak,which is an upgraded EXL-50 device with a central solenoid ...This study investigates the single-pass absorption(SPA) of ion cyclotron range of frequency(ICRF) heating in hydrogen plasma of the EXL-50U spherical tokamak,which is an upgraded EXL-50 device with a central solenoid and a stronger magnetic field.The reliability of the kinetic dispersion equation is confirmed by the one-dimensional full-wave code,and the applicability of Porkolab's simplified theoretical SPA model is discussed based on the kinetic dispersion equation.Simulations are conducted to investigate the heating effects of the fundamental and second harmonic frequencies.The results indicate that with the design parameters of the EXL-50U device,the SPA for second harmonic heating is 63%,while the SPA for fundamental heating is 13%.Additionally,the optimal injection frequencies are 23 MHz at 0.9 T and 31 MHz at 1.2 T.The wave vector of the antenna parallel to the magnetic field,with a value of k_‖=7.5 m^(-1),falls within the optimal heating region.Simulations reveal that the ICRF heating system can play an important role in the ion heating of the EXL-50U.展开更多
Stabilization of tearing modes and neoclassical tearing modes is of great importance for tokamak operation.Electron cyclotron waves(ECWs)have been extensively used to stabilize the tearing modes with the virtue of hig...Stabilization of tearing modes and neoclassical tearing modes is of great importance for tokamak operation.Electron cyclotron waves(ECWs)have been extensively used to stabilize the tearing modes with the virtue of highly localized power deposition.Complete suppression of the m/n=2/1 tearing mode(TM)by electron cyclotron resonance heating(ECRH)has been achieved successfully on the J-TEXT tokamak.The effects of ECW deposition location and power amplitude on the 2/1 TM suppression have been investigated.It is found that the suppression is more effective when the ECW power is deposited closer to the rational surface.As the ECW power increases to approximately 230 k W,the 2/1 TM can be completely suppressed.The island rotation frequency is increased when the island width is reduced.The experimental results show that the local heating inside the magnetic island and the resulting temperature perturbation increase at the O-point of the island play dominant roles in TM suppression.As the ECW power increases,the 2/1 island is suppressed to smaller island width,and the flow shear also plays a stabilizing effect on small magnetic islands.With the stabilizing contribution of heating and flow shear,the 2/1 TM can be completely suppressed.展开更多
A power-supply system was developed for Ohmic heating(OH)to double×10^(18)the amount of change magnetic flux in the primary central solenoid(CS)on the QUEST spherical tokamak.Two power supplies are connected with...A power-supply system was developed for Ohmic heating(OH)to double×10^(18)the amount of change magnetic flux in the primary central solenoid(CS)on the QUEST spherical tokamak.Two power supplies are connected with stacks of insulated-gate bipolar transistors,and sequentially operated to generate positive and negative CS currents.This bipolar power-supply system is controlled via a field-programmable gate array,which guarantees the safety of the entire system operation.The new OH system,assisted by electron cyclotron heating,enables the stable generation of plasma currents exceeding 100 k A.Moreover,the achieved electron density over the wide range in the major radial direction exceeds the cut-off density for one of the highpower microwave sources in QUEST.This strategy yields target plasmas for future experiments with the electron Bernstein wave.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
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
基金supported by the National Key Research and Development Program of China(Nos.2022YFE03070000 and 2022YFE03070003)National Natural Science Foundation of China(Nos.12375220 and 12075114)。
文摘According to the physics of tokamak start-up,this study constructs a zero-dimensional(0D)model applicable to electron cyclotron(EC)wave assisted start-up in NCST spherical torus(spherical tokamak)and CN-H1 stellarators.Using the constructed 0D model,the results obtained in this study under the same conditions are compared and validated against reference results for pure hydrogen plasma start-up in tokamak.The results are in good agreement,especially regarding electron temperature,ion temperature and plasma current.In the presence of finite Ohmic electric field in the spherical tokamak,a study on the EC wave assisted start-up of the NCST plasma at frequency of 28 GHz is conducted.The impact of the vertical magnetic field B_(v)on EC wave assisted start-up,the relationship between EC wave injection power P_(inj),Ohmic electric field E,and initial hydrogen atom density n_(H0)are explored separately.It is found that under conditions of Ohmic electric field lower than ITER(~0.3 V m^(-1)),EC wave can expand the operational space to achieve better plasma parameters.Simulating the process of28 GHz EC wave start-up in the CN-H1 stellarator plasma,the plasma current in the zerodimensional model is replaced with the current in the poloidal coil of the stellarator.Plasma startup can be successfully achieved at injection powers in the hundreds of kilowatts range,resulting in electron densities on the order of 10^(17)-10^(18)m^(-3).
基金Project supported by the National Key R&D Program of China(Grant Nos.2022YFE03070000 and 2022YFE03070003)the National Natural Science Foundation of China(Grant Nos.12375220 and 12075114)+3 种基金the Hunan Provincial Natural Science Foundation(Grant No.2021JJ30569)the Doctoral Initiation Fund Project of University of South China(Grant No.190XQD114)the Hunan Nuclear Fusion International Science and Technology Innovation Cooperation Base(Grant No.2018WK4009)the Hengyang Key Laboratory of Magnetic Confinement Nuclear Fusion Research(Grant No.2018KJ108)。
文摘Through theoretical analysis,we construct a physical model that includes the influence of counter-external driven current opposite to the plasma current direction in the neoclassical tearing mode(NTM).The equation is used with this model to obtain the modified Rutherford equation with co-current and counter-current contributions.Consistent with the reported experimental results,numerical simulations have shown that the localized counter external current can only partially suppress NTM when it is far from the resonant magnetic surface.Under some circumstances,the Ohkawa mechanism dominated current drive(OKCD)by electron cyclotron waves can concurrently create both co-current and counter-current.In this instance,the minimal electron cyclotron wave power that suppresses a particular NTM was calculated by the Rutherford equation.The result is marginally less than when taking co-current alone into consideration.As a result,to suppress NTM using OKCD,one only needs to align the co-current with a greater OKCD peak well with the resonant magnetic surface.The effect of its lower counter-current does not need to be considered because the location of the counter-current deviates greatly from the resonant magnetic surface.
文摘Anomalous ion heat transport is analyzed in the T-10 tokamak plasma heated with electron cyclotron resonance heating(ECRH) in second-harmonic extra-ordinary mode. Predictive modeling with empirical scaling for Ohmical heat conductivity shows that in ECRH plasmas the calculated ion temperature could be overestimated, so an increase of anomalous ion heat transport is required. To study this effect two scans are presented: over the EC resonance position and over the ECRH power. The EC resonance position varies from the high-field side to the low-field side by variation of the toroidal magnetic field. The scan over the heating power is presented with on-axis and mixed ECRH regimes. Discharges with high anomalous ion heat transport are obtained in all considered regimes. In these discharges the power balance ion heat conductivity exceeds the neoclassical level by up to 10 times. The high ion heat transport regimes are distinguished by three parameters: the ratio Te/Ti, the normalized electron density gradient R/■, and the ion–ion collisionality νii~*. The combination of high Te/Ti, high νii~*, and R/■=6-10 results in values of normalized anomalous ion heat fluxes up to 10 times higher than in the low transport scenario.
文摘This paper describes the experimental analysis and preliminary investigation of the predictability of pitch angle scattering(PAS) events through the electron cyclotron emission(ECE)radiometer signals at the ADITYA-Upgrade(ADITYA-U) tokamak. For low-density discharges at ADITYA-U, a sudden abnormal rise is observed in the ECE signature while other plasma parameters are unchanged. Investigations are done to understand this abrupt rise that is expected to occur due to PAS. The rise time is as fast as 100 μs with a single step and/or multiple step rise in ECE radiometer measurements. This event is known to limit the on-axis energy of runaway electrons. Being a repetitive event, the conditions of its repetitive occurrence can be investigated, thereby exploring the possibility of it being triggered and surveyed as an alternate runaway electron mitigation plan. Functional parameterization of such events with other discharge parameters is obtained and the possibility to trigger these events is discussed.PREDICT code is used to investigate the possible interpretations for the PAS occurrence through modeling and supporting the ECE observations. The trigger values so obtained experimentally are set as input criteria for PAS occurrence. Preliminary modeling investigations provide reliable consistency with the findings.
基金performed under the auspices of National Natural Science Foundation of China(No.11605244)supported by the High-End Talents Program of Hebei Province,Innovative Approaches towards Development of CarbonFree Clean Fusion Energy(No.2021HBQZYCSB006)。
文摘The electron cyclotron emission(ECE)diagnostic system has been developed on the ENN spherical torus(EXL-50).The ECE system is designed to detect radiation emitted by energetic electrons,rather than conventional 1D electron temperature profile measurement,in the frequency range of 4-40 GHz.The system is composed of five subsystems,each covering a different frequency band,including the C-band(4-8 GHz),X-band(8-12 GHz),Ku-band(12-18 GHz),K-band(18-26.5 GHz)and Kα-band(26.4-40 GHz).The system uses heterodyne detection to analyze the received signals.The K-band and Kα-band subsystems are located horizontally in the equatorial plane of the EXL-50,while the C-band,X-band and Ku-band subsystems are located under the vacuum vessel of the EXL-50.To direct the microwaves from the plasma to the antennas for the horizontal detection subsystems,a quasi-optical system has been developed.For the vertical detection subsystems,the antennas are directly attached to the port located beneath the torus at R=700 mm,which is also the magnetic axis of the torus.The system integration,bench testing and initial experimental results will be thoroughly discussed,providing a comprehensive understanding of the ECE system s performance and capabilities.
基金supported by the National Magnetic Confinement Fusion Energy Program of China (No.2018 YFE0311300)the High-End Talents Program of Hebei Province, Innovative Approaches Towards Development of Carbon-Free Clean Fusion Energy (No.2021HBQZYCSB 006)the Compact Fusion Project of the ENN Group。
文摘This study investigates the single-pass absorption(SPA) of ion cyclotron range of frequency(ICRF) heating in hydrogen plasma of the EXL-50U spherical tokamak,which is an upgraded EXL-50 device with a central solenoid and a stronger magnetic field.The reliability of the kinetic dispersion equation is confirmed by the one-dimensional full-wave code,and the applicability of Porkolab's simplified theoretical SPA model is discussed based on the kinetic dispersion equation.Simulations are conducted to investigate the heating effects of the fundamental and second harmonic frequencies.The results indicate that with the design parameters of the EXL-50U device,the SPA for second harmonic heating is 63%,while the SPA for fundamental heating is 13%.Additionally,the optimal injection frequencies are 23 MHz at 0.9 T and 31 MHz at 1.2 T.The wave vector of the antenna parallel to the magnetic field,with a value of k_‖=7.5 m^(-1),falls within the optimal heating region.Simulations reveal that the ICRF heating system can play an important role in the ion heating of the EXL-50U.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China(No.2019YFE03010004)the Hubei Provincial Natural Science Foundation of China(No.2022CFA072)National Natural Science Foundation of China(No.51821005)。
文摘Stabilization of tearing modes and neoclassical tearing modes is of great importance for tokamak operation.Electron cyclotron waves(ECWs)have been extensively used to stabilize the tearing modes with the virtue of highly localized power deposition.Complete suppression of the m/n=2/1 tearing mode(TM)by electron cyclotron resonance heating(ECRH)has been achieved successfully on the J-TEXT tokamak.The effects of ECW deposition location and power amplitude on the 2/1 TM suppression have been investigated.It is found that the suppression is more effective when the ECW power is deposited closer to the rational surface.As the ECW power increases to approximately 230 k W,the 2/1 TM can be completely suppressed.The island rotation frequency is increased when the island width is reduced.The experimental results show that the local heating inside the magnetic island and the resulting temperature perturbation increase at the O-point of the island play dominant roles in TM suppression.As the ECW power increases,the 2/1 island is suppressed to smaller island width,and the flow shear also plays a stabilizing effect on small magnetic islands.With the stabilizing contribution of heating and flow shear,the 2/1 TM can be completely suppressed.
基金supported by the NIFS Bilateral Collaboration Research Program(Nos.NIFS19-KUTR136,NIFS22KUTR169)Grant-in-Aid for Scientific Research(C)(No.21K03510)Collaborative Research Program of the RIAM in Kyushu University。
文摘A power-supply system was developed for Ohmic heating(OH)to double×10^(18)the amount of change magnetic flux in the primary central solenoid(CS)on the QUEST spherical tokamak.Two power supplies are connected with stacks of insulated-gate bipolar transistors,and sequentially operated to generate positive and negative CS currents.This bipolar power-supply system is controlled via a field-programmable gate array,which guarantees the safety of the entire system operation.The new OH system,assisted by electron cyclotron heating,enables the stable generation of plasma currents exceeding 100 k A.Moreover,the achieved electron density over the wide range in the major radial direction exceeds the cut-off density for one of the highpower microwave sources in QUEST.This strategy yields target plasmas for future experiments with the electron Bernstein wave.
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.
