Solid-state electrolytes with high oxidation stability are crucial for achieving high power density allsolid-state lithium batteries.Halide electrolytes are promising candidates due to their outstanding compatibility ...Solid-state electrolytes with high oxidation stability are crucial for achieving high power density allsolid-state lithium batteries.Halide electrolytes are promising candidates due to their outstanding compatibility with cathode materials and high Li^(+)conductivity.However,the electrochemical stability of chloride electrolytes is still limited,leaving them unsuitable for ultrahigh voltage operation.Besides,chemical compatibility issue between sulfide and halide electrolytes affects the electrochemical performance of all-solid-state batteries.Herein,Li-ion conductor Li_(3+x)InCl_(6-x)O_(x) is designed to address these challenges.Li_(3.25)InCl_(5.75)O_(0.25)shows a Li-ion conductivity of 0.90 mS cm^(-1)at room temperature,a high onset oxidation voltage of 3.84 V,fewer by-products at ultrahigh operation voltage,and good chemical compatibility with Li_(5.5)PS_(4.5)Cl_(1.5).The Li_(3.25)InCl_(5.75)O_(0.25)@LiNi_(0.7)Co_(0.1)Mn_(0.2)O_(2)-Li_(3.25)InCl_(5.75)O_(0.25)-VGCF/Li_(3.25)InCl_(5.75)O_(0.25)/Li_(5.5)PS_(4.5)Cl_(1.5)/Li-In battery delivers good electrochemical performances at high operating voltage.This work provides a simple,economical,and effective strategy for designing high-voltage all-solid-state electrolytes.展开更多
Explorations into new electrolytes have highlighted the critical impact of solvation structure on battery performance,Classical molecular dynamics(CMD)using semi-empirical force fields has become an essential tool for...Explorations into new electrolytes have highlighted the critical impact of solvation structure on battery performance,Classical molecular dynamics(CMD)using semi-empirical force fields has become an essential tool for simulating solvation structures.However,mainstream force fields often lack accuracy in describing strong ion-solvent interactions,causing disparities between CMD simulations and experimental observations.Although some empirical methods have been employed in some of the studies to address this issue,their effectiveness has been limited.Our CMD research,supported by quantum chemical calculations and experimental data,reveals that the solvation structure is influenced not only by the charge model but also by the polarization description.Previous empirical approaches that focused solely on adjusting ion-solvent interaction strengths overlooked the importance of polarization effects.Building on this insight,we propose integrating the Drude polarization model into mainstream force fields and verify its feasibility in carbonate,ether,and nitrile electrolytes.Our experimental results demonstrate that this approach significantly enhances the accuracy of CMD-simulated solvation structures.This work is expected to provide a more reliable CMD method for electrolyte design,shielding researchers from the pitfalls of erroneous simulation outcomes.展开更多
The application of superconducting(SC)technology enables magnets to excite strong fields with small footprints,which has great potential for miniaturizing proton therapy gantries.However,the slow ramping rate of SC ma...The application of superconducting(SC)technology enables magnets to excite strong fields with small footprints,which has great potential for miniaturizing proton therapy gantries.However,the slow ramping rate of SC magnets results in a low treatment efficiency compared with normal-conducting(NC)gantries.To address this problem,this study proposes a compact proton therapy gantry design with a large momentum acceptance utilizing alternating-gradient canted-cosine-theta(AG-CCT)SC magnets.In our design,a high-transmission degrader is mounted in the middle of the gantry,and the upstream beamline employs NC magnets with small apertures.Downstream of the degrader,large-bore AG-CCT magnets with strong alternating focusing gradients are set symmetrically as a local achromat,which realizes a momentum acceptance of 20%(or 40%in the energy domain).Therefore,only three magnetic working points are required to cover a treatment energy of 70-230 Me V.Owing to the large momentum acceptance,the proton beam after the degrader can be directly delivered to the isocenter without truncating its energy spectrum,which can significantly increase the treatment efficiency but causes severe dispersion effects during pencil beam scanning.Therefore,a compensation method was introduced by tuning the normal and skewed quadrupoles during the scanning process.As a result,the new gantry not only presents a remarkable reduction in the size and weight of the facility but also shows good potential for fast treatment.展开更多
An advanced spectral diagnostic system was developed to measure the electron temperature(T_(e)),electron density(N_(e)),and ion temperature(T_(i))of the Huazhong University of Science and Technology field-reversed con...An advanced spectral diagnostic system was developed to measure the electron temperature(T_(e)),electron density(N_(e)),and ion temperature(T_(i))of the Huazhong University of Science and Technology field-reversed configuration plasma.The system consists of an optic fiber spectrometer with a wide spectral band and a 670 mm focal length high throughout Czerny-Turner monochromator equipped with both a 3600 g mm^(-1)grating and a 2400 g mm^(-1)grating to measure the line spectrum.Accompanying these components is an electronmultiplying charge-coupled device camera to capture spectral data.The relative intensity of the optical fiber spectrometer was calibrated using a standard luminance source,and the wavelength calibration of the spectrometer was accomplished using a Hg/Ar lamp.This diagnostic setup was configured to measure electron density based on the Stark effect of H_γ(n=5→n=2;434.04 nm).Doppler broadening of an OⅢ(2s^(2)2p(^(2)P^(0))3p→2s^(2)2p(^(2)P^(0))3s;375.988 nm)emission line was measured and analyzed to obtain the ion temperature,and electron temperatures were estimated from the relative strength of H_(β)(n=4→n=2;486.14 nm)(D_(β))and H_(γ)(D_(γ))spectral lines when the electron density was obtained from Stark effect measurements.The initial experimental results indicate that the highest electron temperature of the formation region was approximately 8 eV,the electron density of the colliding-and-merging region was approaching 10^(20)m^(-3),and the ion temperature reached about 40 eV.展开更多
The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)conten...The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped formation.When the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.展开更多
On J-TEXT,the temporal evolution of heat flux distribution on the high-field side(HFS)divertor plate has been measured by an infrared(IR)camera during the plasma operation with an island divertor configuration.In expe...On J-TEXT,the temporal evolution of heat flux distribution on the high-field side(HFS)divertor plate has been measured by an infrared(IR)camera during the plasma operation with an island divertor configuration.In experiments,the island divertor configuration is an edge magnetic island chain structure surrounded by stochastic layers,which can be induced by resonant magnetic perturbations(RMPs).The experimental results show that the heat flux distribution on the HFS target plate depends significantly on the edge magnetic topology.Furthermore,the impact of hydrogen fueling using supersonic molecular beam injection(SMBI)on the divertor heat flux distributions is studied on J-TEXT with an island divertor configuration.It has been observed that power detachment can be achieved when the radiation front approaches the last closed flux surface(LCFS)after each SMBI pulse.This result may provide a method of access for divertor detachment on a fusion device with a three-dimensional(3D)boundary magnetic structure.展开更多
Density limit has long been a widely studied issue influencing the operating range of tokamaks.The rapid growth of the m/n=2/1(where m and n are poloidal and toroidal mode numbers,respectively)tearing mode is generall...Density limit has long been a widely studied issue influencing the operating range of tokamaks.The rapid growth of the m/n=2/1(where m and n are poloidal and toroidal mode numbers,respectively)tearing mode is generally regarded as a primary precursor to the density limit disruption.In this experiment,the coupling of the m/n=1/1 mode and the m/n=2/1 mode in highdensity plasma was observed.During a sawtooth cycle,the frequencies of the two modes gradually converge until they become equal.After that,toroidal coupling occurs between the 1/1 and 2/1 modes,resulting in a mutually fixed phase relationship.With the occurrence of toroidal coupling,the 2/1 mode is stabilized.Prior to the disruption,the cessation of the 1/1 and 2/1 mode coupling,along with the rapid growth in the amplitude of the 2/1 mode,can be observed.Additionally,under the same parameters,comparing discharges with or without the 1/1 mode,it is found that the presence of the 1/1 mode leads to higher plasma density and temperature parameters.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
Three-dimensional(3D) equilibrium calculations, including the plasma rotation shielding effect to resonant magnetic perturbations(RMPs) produced by the island divertor(ID) coils, were carried out using the HINT and MA...Three-dimensional(3D) equilibrium calculations, including the plasma rotation shielding effect to resonant magnetic perturbations(RMPs) produced by the island divertor(ID) coils, were carried out using the HINT and MARS-F codes on J-TEXT. Validation of 3D equilibrium calculations with experimental observations demonstrates that the shielding effect will prevent the penetration of the edge m/n = 3/1 mode component when the ID coil current is 4 k A, while change the size of magnetic islands once the current exceeds the penetration threshold. This indicates that equilibrium calculations including the plasma rotation shielding effect to RMPs can lead to better agreements with experimental observations compared to the vacuum approximation method. Additionally, the magnetic topology at the boundary undergoes changes,impacting the interaction between the plasma and the target plate. These results may be important in understanding RMP effects on edge transport and magnetohydrodynamic(MHD)instability control, as well as divertor heat and particle flux distribution control.展开更多
Following the reconstruction of the TEXT tokamak at Huazhong University of Science and Technology in China, renamed as J-TEXT, a plethora of experimental and theoretical investigations has been conducted to elucidate ...Following the reconstruction of the TEXT tokamak at Huazhong University of Science and Technology in China, renamed as J-TEXT, a plethora of experimental and theoretical investigations has been conducted to elucidate the intricacies of turbulent transport within the tokamak configuration. These endeavors encompass not only the J-TEXT device's experimental advancements but also delve into critical issues pertinent to the optimization of future fusion devices and reactors. The research includes topics on the suppression of turbulence, flow drive and damping, density limit, non-local transport, intrinsic toroidal flow, turbulence and flow with magnetic islands, turbulent transport in the stochastic layer, and turbulence and zonal flow with energetic particles or helium ash. Several important achievements have been made in the last few years, which will be further elaborated upon in this comprehensive review.展开更多
Elevating the upper cutoff voltage to 4.6 V could effec-tively increase the reversible capacity ofLiCoO_(2)(LCO)cathode,whereas the irreversible structural transition,unstable electrode/electrolyte interface and poten...Elevating the upper cutoff voltage to 4.6 V could effec-tively increase the reversible capacity ofLiCoO_(2)(LCO)cathode,whereas the irreversible structural transition,unstable electrode/electrolyte interface and potentially induced safety hazards severely hinder its industrial application.Building a robust cathode/electrolyte interface film by electrolyte engineer-ing is one of the efficient approaches to boost the performance of high-voltage LCO(HV-LCO);however,the elusive interfacial chemistry poses substantial challenges to the rational design of highly compatible electrolytes.Herein,we propose a novel electrolyte design strategy and screen proper solvents based on two factors:highest occupied molecular orbital energy level and LCO absorption energy.Tris(2,2,2-trifluoroethyl)phosphate is determined as the optimal solvent,whose low defluorination energy barrier significantly promotes the construction of LiF-rich cathode/electrolyte interface layer on the surface of LCO,thereby eventually suppresses the phase transition and enhancesLi+diffusion kinetics.The rationally designed electrolyte endows graphite||HV-LCO pouch cells with long cycle life(85.3%capacity retention after 700 cycles),wide-temperature adaptability(-60–80℃)and high safety(pass nail penetration).This work provides new insights into the electrolyte screening and rational design to constructing stable interface for high-energy lithium-ion batteries.展开更多
High-performance ion-conducting hydrogels(ICHs)are vital for developing flexible electronic devices.However,the robustness and ion-conducting behavior of ICHs deteriorate at extreme tempera-tures,hampering their use i...High-performance ion-conducting hydrogels(ICHs)are vital for developing flexible electronic devices.However,the robustness and ion-conducting behavior of ICHs deteriorate at extreme tempera-tures,hampering their use in soft electronics.To resolve these issues,a method involving freeze–thawing and ionizing radiation technology is reported herein for synthesizing a novel double-network(DN)ICH based on a poly(ionic liquid)/MXene/poly(vinyl alcohol)(PMP DN ICH)system.The well-designed ICH exhibits outstanding ionic conductivity(63.89 mS cm^(-1) at 25℃),excellent temperature resistance(-60–80℃),prolonged stability(30 d at ambient temperature),high oxidation resist-ance,remarkable antibacterial activity,decent mechanical performance,and adhesion.Additionally,the ICH performs effectively in a flexible wireless strain sensor,thermal sensor,all-solid-state supercapacitor,and single-electrode triboelectric nanogenerator,thereby highlighting its viability in constructing soft electronic devices.The highly integrated gel structure endows these flexible electronic devices with stable,reliable signal output performance.In particular,the all-solid-state supercapacitor containing the PMP DN ICH electrolyte exhibits a high areal specific capacitance of 253.38 mF cm^(-2)(current density,1 mA cm^(-2))and excellent environmental adaptability.This study paves the way for the design and fabrication of high-performance mul-tifunctional/flexible ICHs for wearable sensing,energy-storage,and energy-harvesting applications.展开更多
Lithium metal batteries(LMBs) promise energy density over 400 Wh kg^(-1).However,they suffer severe electrochemical performance deterioration at sub-zero temperatures.Such failure behavior highly correlates to inferio...Lithium metal batteries(LMBs) promise energy density over 400 Wh kg^(-1).However,they suffer severe electrochemical performance deterioration at sub-zero temperatures.Such failure behavior highly correlates to inferior lithium metal anode(LMA) compatibility and sluggish Li^(+) desolvation.Here,we demonstrate that cyclopentylmethyl ether(CPME) based diluted high-concentration electrolyte(DHCE)enables-60℃ LMBs operation.By leveraging the loose coordination between Li^(+) and CPME,such developed electrolyte boosts the formation of ion clusters to derive anion-dominant interfacial chemistry for enhancing LMA compatibility and greatly accelerates Li^(+) desolvation kinetics.The resulting electrolyte demonstrates high Coulombic efficiencies(CE),providing over 99.5%,99.1%,98.5% and 95% at 25,-20,-40,and-60℃respectively.The assembled Li-S battery exhibits remarkable cyclic stability in-20,and-40℃ at 0.2 C charging and 0.5 C discharging.Even at-60℃,Li-S cell with this designed electrolyte retains> 70% of the initial capacity over 170 cycles.Besides,lithium metal coin cell and pouch cell with10 mg cm^(-2) high S cathode loading exhibit cycling stability at-20℃.This work offers an opportunity for rational designing electrolytes toward low temperature LMBs.展开更多
An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant surfaces.We have studied the plasma responses using Fitzpatrick's improved two-fluid model and pr...An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant surfaces.We have studied the plasma responses using Fitzpatrick's improved two-fluid model and program LAYER.We calculated the error field penetration threshold for J-TEXT.In addition,we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration value.However,the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the penetration.By scanning the natural mode frequency,we find that the shielding effect of the plasma decreases as the natural mode frequency decreases.Finally,we obtain the m/n=2/1 penetration threshold scaling on density and temperature.展开更多
The field-reversed configuration(FRC)plasma thruster driven by rotating magnetic field(RMF),abbreviated as the RMF-FRC thruster,is a new type of electric propulsion technology that is expected to accelerate the deep s...The field-reversed configuration(FRC)plasma thruster driven by rotating magnetic field(RMF),abbreviated as the RMF-FRC thruster,is a new type of electric propulsion technology that is expected to accelerate the deep space exploration.An experimental prototype,including diagnostic devices,was designed and constructed based on the principles of the RMF-FRC thruster,with an RMF frequency of 210 kHz and a maximum peak current of 2 kA.Under the rated operating conditions,the initial plasma density was measured to be 5×10^(17)m^(-3),and increased to 2.2×10^(19)m^(-3)after the action of RMF.The coupling efficiency of RMF was about 53%,and the plasma current reached 1.9 kA.The axial magnetic field changed in reverse by 155 Gauss,successfully reversing the bias magnetic field of 60 Gauss,which verifies the formation of FRC plasma.After optimization research,it was found that when the bias magnetic field is 100 Gauss,the axial magnetic field reverse variation caused by FRC is the highest at 164 Gauss.The experimental results are discussed and strategies are proposed to improve the performance of the prototype.展开更多
A large number of runaway electrons(REs)generated during disruption can cause significant damage to next-generation large-scale tokamaks.The influence of three-dimensional(3D)helical magnetic perturbations on the supp...A large number of runaway electrons(REs)generated during disruption can cause significant damage to next-generation large-scale tokamaks.The influence of three-dimensional(3D)helical magnetic perturbations on the suppression of RE generation was explored using a set of 3D helical coils in J-TEXT tokamak,which can excite m/n=-2/2 helical magnetic perturbations.Experimental evidence shows that the-2/2 magnetic perturbations caused by the opposite coil current direct plasma toward the high-field side,simultaneously enhancing the magnetic fluctuations,which would enhance the radial loss of REs and even prevent RE generation.On the other hand,-2/2 magnetic perturbations can also reduce the cooling time during the disruption phase and generate a population of high-energy REs,which can interact with high-frequency magnetic fluctuations and in turn suppress RE generation.The critical helical coil current was found to correlate with electron density,requiring higher coil currents at higher densities.According to the statistical analysis of RE generation at different electron densities,the applied-2/2 magnetic perturbations can increase the magnetic fluctuations to the same level at lower electron densities,which can decrease the threshold electron density for RE suppression.This will be beneficial for RE mitigation in future large tokamak devices.展开更多
Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scannin...Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness.However,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread application.This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions.Preliminary corrections were explored through a combination of data processing analysis and numerical simulations.Furthermore,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability.Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method.Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions.Through the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.展开更多
基金supported by the National Key Research and Development Program of China(2021YFB2500200)the National Natural Science Foundation of China(52177214,52222703)for supporting our workJiangsu Funding Program for Excellent Postdoctoral Talent for the support。
文摘Solid-state electrolytes with high oxidation stability are crucial for achieving high power density allsolid-state lithium batteries.Halide electrolytes are promising candidates due to their outstanding compatibility with cathode materials and high Li^(+)conductivity.However,the electrochemical stability of chloride electrolytes is still limited,leaving them unsuitable for ultrahigh voltage operation.Besides,chemical compatibility issue between sulfide and halide electrolytes affects the electrochemical performance of all-solid-state batteries.Herein,Li-ion conductor Li_(3+x)InCl_(6-x)O_(x) is designed to address these challenges.Li_(3.25)InCl_(5.75)O_(0.25)shows a Li-ion conductivity of 0.90 mS cm^(-1)at room temperature,a high onset oxidation voltage of 3.84 V,fewer by-products at ultrahigh operation voltage,and good chemical compatibility with Li_(5.5)PS_(4.5)Cl_(1.5).The Li_(3.25)InCl_(5.75)O_(0.25)@LiNi_(0.7)Co_(0.1)Mn_(0.2)O_(2)-Li_(3.25)InCl_(5.75)O_(0.25)-VGCF/Li_(3.25)InCl_(5.75)O_(0.25)/Li_(5.5)PS_(4.5)Cl_(1.5)/Li-In battery delivers good electrochemical performances at high operating voltage.This work provides a simple,economical,and effective strategy for designing high-voltage all-solid-state electrolytes.
基金supported by the Science and Technology Project of State Grid Corporation of China(5419-202199552A-0-5-ZN).
文摘Explorations into new electrolytes have highlighted the critical impact of solvation structure on battery performance,Classical molecular dynamics(CMD)using semi-empirical force fields has become an essential tool for simulating solvation structures.However,mainstream force fields often lack accuracy in describing strong ion-solvent interactions,causing disparities between CMD simulations and experimental observations.Although some empirical methods have been employed in some of the studies to address this issue,their effectiveness has been limited.Our CMD research,supported by quantum chemical calculations and experimental data,reveals that the solvation structure is influenced not only by the charge model but also by the polarization description.Previous empirical approaches that focused solely on adjusting ion-solvent interaction strengths overlooked the importance of polarization effects.Building on this insight,we propose integrating the Drude polarization model into mainstream force fields and verify its feasibility in carbonate,ether,and nitrile electrolytes.Our experimental results demonstrate that this approach significantly enhances the accuracy of CMD-simulated solvation structures.This work is expected to provide a more reliable CMD method for electrolyte design,shielding researchers from the pitfalls of erroneous simulation outcomes.
基金supported by the National Natural Science Foundation of China(No.11975107,12205111)。
文摘The application of superconducting(SC)technology enables magnets to excite strong fields with small footprints,which has great potential for miniaturizing proton therapy gantries.However,the slow ramping rate of SC magnets results in a low treatment efficiency compared with normal-conducting(NC)gantries.To address this problem,this study proposes a compact proton therapy gantry design with a large momentum acceptance utilizing alternating-gradient canted-cosine-theta(AG-CCT)SC magnets.In our design,a high-transmission degrader is mounted in the middle of the gantry,and the upstream beamline employs NC magnets with small apertures.Downstream of the degrader,large-bore AG-CCT magnets with strong alternating focusing gradients are set symmetrically as a local achromat,which realizes a momentum acceptance of 20%(or 40%in the energy domain).Therefore,only three magnetic working points are required to cover a treatment energy of 70-230 Me V.Owing to the large momentum acceptance,the proton beam after the degrader can be directly delivered to the isocenter without truncating its energy spectrum,which can significantly increase the treatment efficiency but causes severe dispersion effects during pencil beam scanning.Therefore,a compensation method was introduced by tuning the normal and skewed quadrupoles during the scanning process.As a result,the new gantry not only presents a remarkable reduction in the size and weight of the facility but also shows good potential for fast treatment.
基金supported by National Natural Science Foundation of China(Nos.2017YFE0301804,2017YFE0301803)Technology Innovation Platform Project of Wuhan(No.20200766)。
文摘An advanced spectral diagnostic system was developed to measure the electron temperature(T_(e)),electron density(N_(e)),and ion temperature(T_(i))of the Huazhong University of Science and Technology field-reversed configuration plasma.The system consists of an optic fiber spectrometer with a wide spectral band and a 670 mm focal length high throughout Czerny-Turner monochromator equipped with both a 3600 g mm^(-1)grating and a 2400 g mm^(-1)grating to measure the line spectrum.Accompanying these components is an electronmultiplying charge-coupled device camera to capture spectral data.The relative intensity of the optical fiber spectrometer was calibrated using a standard luminance source,and the wavelength calibration of the spectrometer was accomplished using a Hg/Ar lamp.This diagnostic setup was configured to measure electron density based on the Stark effect of H_γ(n=5→n=2;434.04 nm).Doppler broadening of an OⅢ(2s^(2)2p(^(2)P^(0))3p→2s^(2)2p(^(2)P^(0))3s;375.988 nm)emission line was measured and analyzed to obtain the ion temperature,and electron temperatures were estimated from the relative strength of H_(β)(n=4→n=2;486.14 nm)(D_(β))and H_(γ)(D_(γ))spectral lines when the electron density was obtained from Stark effect measurements.The initial experimental results indicate that the highest electron temperature of the formation region was approximately 8 eV,the electron density of the colliding-and-merging region was approaching 10^(20)m^(-3),and the ion temperature reached about 40 eV.
基金financial support from the Interdisciplinary Fund of the Wuhan National High Magnetic Field Center (No. WHMFC202101)。
文摘The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped formation.When the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China(No.2018YFE0309103)National Natural Science Foundation of China(Nos.12305243 and 51821005)。
文摘On J-TEXT,the temporal evolution of heat flux distribution on the high-field side(HFS)divertor plate has been measured by an infrared(IR)camera during the plasma operation with an island divertor configuration.In experiments,the island divertor configuration is an edge magnetic island chain structure surrounded by stochastic layers,which can be induced by resonant magnetic perturbations(RMPs).The experimental results show that the heat flux distribution on the HFS target plate depends significantly on the edge magnetic topology.Furthermore,the impact of hydrogen fueling using supersonic molecular beam injection(SMBI)on the divertor heat flux distributions is studied on J-TEXT with an island divertor configuration.It has been observed that power detachment can be achieved when the radiation front approaches the last closed flux surface(LCFS)after each SMBI pulse.This result may provide a method of access for divertor detachment on a fusion device with a three-dimensional(3D)boundary magnetic structure.
基金supported by National Natural Science Foundation of China(Nos.12175227 and 51821005)the Fundamental Research Funds for the Central Universities(No.USTC 20210079)the Collaborative Innovation Program of Hefei Science Center,CAS(No.2022HSC-CIP022)。
文摘Density limit has long been a widely studied issue influencing the operating range of tokamaks.The rapid growth of the m/n=2/1(where m and n are poloidal and toroidal mode numbers,respectively)tearing mode is generally regarded as a primary precursor to the density limit disruption.In this experiment,the coupling of the m/n=1/1 mode and the m/n=2/1 mode in highdensity plasma was observed.During a sawtooth cycle,the frequencies of the two modes gradually converge until they become equal.After that,toroidal coupling occurs between the 1/1 and 2/1 modes,resulting in a mutually fixed phase relationship.With the occurrence of toroidal coupling,the 2/1 mode is stabilized.Prior to the disruption,the cessation of the 1/1 and 2/1 mode coupling,along with the rapid growth in the amplitude of the 2/1 mode,can be observed.Additionally,under the same parameters,comparing discharges with or without the 1/1 mode,it is found that the presence of the 1/1 mode leads to higher plasma density and temperature parameters.
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 National Magnetic Confinement Fusion Energy R & D Program of China (No. 2018 YFE0309101)National Natural Science Foundation of China (Nos. 12305243 and 51821005)。
文摘Three-dimensional(3D) equilibrium calculations, including the plasma rotation shielding effect to resonant magnetic perturbations(RMPs) produced by the island divertor(ID) coils, were carried out using the HINT and MARS-F codes on J-TEXT. Validation of 3D equilibrium calculations with experimental observations demonstrates that the shielding effect will prevent the penetration of the edge m/n = 3/1 mode component when the ID coil current is 4 k A, while change the size of magnetic islands once the current exceeds the penetration threshold. This indicates that equilibrium calculations including the plasma rotation shielding effect to RMPs can lead to better agreements with experimental observations compared to the vacuum approximation method. Additionally, the magnetic topology at the boundary undergoes changes,impacting the interaction between the plasma and the target plate. These results may be important in understanding RMP effects on edge transport and magnetohydrodynamic(MHD)instability control, as well as divertor heat and particle flux distribution control.
基金supported by the National Key R&D Program of China (Nos. 2022YFE03100004, 2017YFE0302000, and 2017YFE0301100)National Natural Science Foundation of China (Nos. 12275097, 12275096, 11875292, 11675059, 11905079, 11305071, and 51821005)+5 种基金the Ministry of Science and Technology of China (No. 2013GB112002)the Project of Science and Technology Department of Sichuan Province (No. 2022NSFSC1791)the Natural Science Foundation of Anhui Province (No. 2208085J39)the Fundamental Research Funds for the Central Universities, HUST: (Nos. 2019kfy XMBZ034 and 2021XXJS007)the Initiative Postdocs Supporting Program of China (No. BX20180105)the US Department of Energy, Office of Science, Office of Fusion Energy Sciences (Nos. DEFG02-04ER54738 and DE-SC-0020287)。
文摘Following the reconstruction of the TEXT tokamak at Huazhong University of Science and Technology in China, renamed as J-TEXT, a plethora of experimental and theoretical investigations has been conducted to elucidate the intricacies of turbulent transport within the tokamak configuration. These endeavors encompass not only the J-TEXT device's experimental advancements but also delve into critical issues pertinent to the optimization of future fusion devices and reactors. The research includes topics on the suppression of turbulence, flow drive and damping, density limit, non-local transport, intrinsic toroidal flow, turbulence and flow with magnetic islands, turbulent transport in the stochastic layer, and turbulence and zonal flow with energetic particles or helium ash. Several important achievements have been made in the last few years, which will be further elaborated upon in this comprehensive review.
基金financially supported by National Key Research and Development Program of China(2024YFE0213000)National Natural Science Foundation of China(No.U22A20438)+1 种基金Hubei Natural Science Foundation(2023BAB036,2024BAB103)the Key Research and Development Program of Ningxia Hui Autonomous Region(2024BEE02002).
文摘Elevating the upper cutoff voltage to 4.6 V could effec-tively increase the reversible capacity ofLiCoO_(2)(LCO)cathode,whereas the irreversible structural transition,unstable electrode/electrolyte interface and potentially induced safety hazards severely hinder its industrial application.Building a robust cathode/electrolyte interface film by electrolyte engineer-ing is one of the efficient approaches to boost the performance of high-voltage LCO(HV-LCO);however,the elusive interfacial chemistry poses substantial challenges to the rational design of highly compatible electrolytes.Herein,we propose a novel electrolyte design strategy and screen proper solvents based on two factors:highest occupied molecular orbital energy level and LCO absorption energy.Tris(2,2,2-trifluoroethyl)phosphate is determined as the optimal solvent,whose low defluorination energy barrier significantly promotes the construction of LiF-rich cathode/electrolyte interface layer on the surface of LCO,thereby eventually suppresses the phase transition and enhancesLi+diffusion kinetics.The rationally designed electrolyte endows graphite||HV-LCO pouch cells with long cycle life(85.3%capacity retention after 700 cycles),wide-temperature adaptability(-60–80℃)and high safety(pass nail penetration).This work provides new insights into the electrolyte screening and rational design to constructing stable interface for high-energy lithium-ion batteries.
基金the National Natural Science Foundation of China(11875138,52077095).
文摘High-performance ion-conducting hydrogels(ICHs)are vital for developing flexible electronic devices.However,the robustness and ion-conducting behavior of ICHs deteriorate at extreme tempera-tures,hampering their use in soft electronics.To resolve these issues,a method involving freeze–thawing and ionizing radiation technology is reported herein for synthesizing a novel double-network(DN)ICH based on a poly(ionic liquid)/MXene/poly(vinyl alcohol)(PMP DN ICH)system.The well-designed ICH exhibits outstanding ionic conductivity(63.89 mS cm^(-1) at 25℃),excellent temperature resistance(-60–80℃),prolonged stability(30 d at ambient temperature),high oxidation resist-ance,remarkable antibacterial activity,decent mechanical performance,and adhesion.Additionally,the ICH performs effectively in a flexible wireless strain sensor,thermal sensor,all-solid-state supercapacitor,and single-electrode triboelectric nanogenerator,thereby highlighting its viability in constructing soft electronic devices.The highly integrated gel structure endows these flexible electronic devices with stable,reliable signal output performance.In particular,the all-solid-state supercapacitor containing the PMP DN ICH electrolyte exhibits a high areal specific capacitance of 253.38 mF cm^(-2)(current density,1 mA cm^(-2))and excellent environmental adaptability.This study paves the way for the design and fabrication of high-performance mul-tifunctional/flexible ICHs for wearable sensing,energy-storage,and energy-harvesting applications.
基金supported by the National Natural Science Foundation of China(Nos.21975087,22008082)。
文摘Lithium metal batteries(LMBs) promise energy density over 400 Wh kg^(-1).However,they suffer severe electrochemical performance deterioration at sub-zero temperatures.Such failure behavior highly correlates to inferior lithium metal anode(LMA) compatibility and sluggish Li^(+) desolvation.Here,we demonstrate that cyclopentylmethyl ether(CPME) based diluted high-concentration electrolyte(DHCE)enables-60℃ LMBs operation.By leveraging the loose coordination between Li^(+) and CPME,such developed electrolyte boosts the formation of ion clusters to derive anion-dominant interfacial chemistry for enhancing LMA compatibility and greatly accelerates Li^(+) desolvation kinetics.The resulting electrolyte demonstrates high Coulombic efficiencies(CE),providing over 99.5%,99.1%,98.5% and 95% at 25,-20,-40,and-60℃respectively.The assembled Li-S battery exhibits remarkable cyclic stability in-20,and-40℃ at 0.2 C charging and 0.5 C discharging.Even at-60℃,Li-S cell with this designed electrolyte retains> 70% of the initial capacity over 170 cycles.Besides,lithium metal coin cell and pouch cell with10 mg cm^(-2) high S cathode loading exhibit cycling stability at-20℃.This work offers an opportunity for rational designing electrolytes toward low temperature LMBs.
基金Project supported by the National Natural Science Foundation of China (Grant No.51821005)。
文摘An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant surfaces.We have studied the plasma responses using Fitzpatrick's improved two-fluid model and program LAYER.We calculated the error field penetration threshold for J-TEXT.In addition,we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration value.However,the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the penetration.By scanning the natural mode frequency,we find that the shielding effect of the plasma decreases as the natural mode frequency decreases.Finally,we obtain the m/n=2/1 penetration threshold scaling on density and temperature.
基金supported by National Natural Science Foundation of China (NSFC) (Nos.62201217 and 51821005)。
文摘The field-reversed configuration(FRC)plasma thruster driven by rotating magnetic field(RMF),abbreviated as the RMF-FRC thruster,is a new type of electric propulsion technology that is expected to accelerate the deep space exploration.An experimental prototype,including diagnostic devices,was designed and constructed based on the principles of the RMF-FRC thruster,with an RMF frequency of 210 kHz and a maximum peak current of 2 kA.Under the rated operating conditions,the initial plasma density was measured to be 5×10^(17)m^(-3),and increased to 2.2×10^(19)m^(-3)after the action of RMF.The coupling efficiency of RMF was about 53%,and the plasma current reached 1.9 kA.The axial magnetic field changed in reverse by 155 Gauss,successfully reversing the bias magnetic field of 60 Gauss,which verifies the formation of FRC plasma.After optimization research,it was found that when the bias magnetic field is 100 Gauss,the axial magnetic field reverse variation caused by FRC is the highest at 164 Gauss.The experimental results are discussed and strategies are proposed to improve the performance of the prototype.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China (Nos.2018YFE0309103 and 2019YFE03010004)National Natural Science Foundation of China (Nos.12475222,12205122,and 51821005)Hubei International Science and Technology Cooperation Projects (No.2022EHB003)。
文摘A large number of runaway electrons(REs)generated during disruption can cause significant damage to next-generation large-scale tokamaks.The influence of three-dimensional(3D)helical magnetic perturbations on the suppression of RE generation was explored using a set of 3D helical coils in J-TEXT tokamak,which can excite m/n=-2/2 helical magnetic perturbations.Experimental evidence shows that the-2/2 magnetic perturbations caused by the opposite coil current direct plasma toward the high-field side,simultaneously enhancing the magnetic fluctuations,which would enhance the radial loss of REs and even prevent RE generation.On the other hand,-2/2 magnetic perturbations can also reduce the cooling time during the disruption phase and generate a population of high-energy REs,which can interact with high-frequency magnetic fluctuations and in turn suppress RE generation.The critical helical coil current was found to correlate with electron density,requiring higher coil currents at higher densities.According to the statistical analysis of RE generation at different electron densities,the applied-2/2 magnetic perturbations can increase the magnetic fluctuations to the same level at lower electron densities,which can decrease the threshold electron density for RE suppression.This will be beneficial for RE mitigation in future large tokamak devices.
基金supported by the National Natural Science Foundation of China(Nos.12341501 and 11905074)。
文摘Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness.However,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread application.This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions.Preliminary corrections were explored through a combination of data processing analysis and numerical simulations.Furthermore,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability.Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method.Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions.Through the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.
