Transport of fast ions is a crucial issue during the operation of ITER.Redistribution of neutral beam injection(NBI)fast ions by the ideal internal magnetohydrodynamic(MHD)instabilities in ITER is studied utilizing th...Transport of fast ions is a crucial issue during the operation of ITER.Redistribution of neutral beam injection(NBI)fast ions by the ideal internal magnetohydrodynamic(MHD)instabilities in ITER is studied utilizing the guiding-center code ORBIT(White R B and Chance M S 1984Phys.Fluids 272455).Effects of the perturbation amplitude A of the internal kink,the perturbation frequency f of the fishbone instability,and the toroidal mode number n of the internal kink are investigated,respectively,in this work.The n=1 internal kink mode can cause NBI fast ions transporting in real space from regions of 0<s≤0.32 to 0.32<s≤0.53,where s labels the normalized plasma radial coordinate.The transport of fast ions is greater as the perturbation amplitude increases.The maximum relative change of the number of fast ions approaches 5%when the perturbation amplitude rises to 500 G.A strong transport is generated between the regions of 0<s≤0.05 and 0.05<s≤0.12 in the presence of the fishbone instability.Higher frequency results in greater transport,and the number of fast ions in 0<s≤0.05 is reduced by 30%at the fishbone frequency of 100 k Hz.Perturbations with higher n will lead to the excursion of fast ion transport regions outward along the radial direction.The loss of fast ions,however,is not affected by the internal MHD perturbation.Strong transport from 0<s≤0.05 to 0.05<s≤0.12 does not influence the plasma heating power of ITER,since the NBI fast ions are still located in the plasma core.On the other hand,the influence of fast ion transport from 0<s≤0.32 to 0.32<s≤0.53 needs further study.展开更多
As a promising method for fast ion diagnostics,collective Thomson scattering(CTS)can measure the one-dimensional velocity distribution of fast ions with high spatial and temporal resolution.The feasibility of diagnosi...As a promising method for fast ion diagnostics,collective Thomson scattering(CTS)can measure the one-dimensional velocity distribution of fast ions with high spatial and temporal resolution.The feasibility of diagnosing fast ions in a compact high-field tokamak by CTS was studied in this work,and the results showed that a wide range of probing frequencies could be applied.A high-frequency case and a low-frequency case were mainly considered for fast ion diagnostics in a compact high-field tokamak.The use of a high probing frequency could effectively avoid the refraction effect of the beams,while the application of a low probing frequency allows greater flexibility in the selection of scattering angle which may help to improve the spatial resolution.Based on typical plasma conditions(B_(0)=12.2 T,n_(e0)=4.3×10^(20)m^(-3),T_(e0)=22.2 keV,T_(i0)=19.8 keV)for a compact high-field tokamak,a220 GHz CTS diagnostic that utilizes a small scattering angle ofθ=30°and a 160 GHz CTS diagnostic that utilizes an orthogonal geometry were proposed.Further study showed that the high-frequency case could operate in a wider range of plasma conditions and provide more information on fast ions while the low-frequency case could achieve higher spatial resolution of the poloidal direction.展开更多
Although aqueous zinc ion hybrid capacitors have advantageous integration of batteries and supercapacitors,they still suffer from the inherent problems of dendrite growth and interfacial side reactions on Zn anodes.He...Although aqueous zinc ion hybrid capacitors have advantageous integration of batteries and supercapacitors,they still suffer from the inherent problems of dendrite growth and interfacial side reactions on Zn anodes.Herein,a universal fast zinc-ion diffusion layer on a three-dimensional(3 D)mesh structure model is demonstrated to effectively improve Zn plating/stripping reversibility.The fast ion diffusion alloy layer accelerates the Zn^(2+)migration in an orderly manner to homogenize Zn^(2+)flux and overcomes the defects of the commercial mesh substrate,effectively avoiding dendrite growth and side reactions.Consequently,the proof-of-concept silver-zinc alloy modified stainless steel mesh delivers superb reversibility with the high coulombic efficiency over 99.4%at 4 mA cm^(-2)after 1600 cycles and excellent reliability of over 830 h at 1 mA cm^(-2),Its feasibility is also evidenced in commercial zinc ion hybrid capacitors with activated carbon as the cathode.This work enriches the fundamental comprehension of fast zinc-ion diffusion layer combined with a 3 D substrate on the Zn deposition and opens a universal approach to design advanced host for Zn electrodes in zinc ion hybrid capacitors.展开更多
A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） rippl...A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） ripple and magnetohydro- dynamic （MHD） perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbitdeviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD＇perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses.展开更多
New lithium fast ion conductors of Li1.2 ＋ x - y Yx Ti1.9 - x Al0.1Si0. 1Wy P2.9 - y O12 based on LiTi2（PO4）3 were prepared by high temperature solid state reaction using refined natural kaolinite as a starting mat...New lithium fast ion conductors of Li1.2 ＋ x - y Yx Ti1.9 - x Al0.1Si0. 1Wy P2.9 - y O12 based on LiTi2（PO4）3 were prepared by high temperature solid state reaction using refined natural kaolinite as a starting material. X-ray powder diffraction analysis indicates that a phase with Nasieon-like structure exists together with other phases in the composition range of x =0.1, y≤0.2 and x =0.2,y ≤0.2. AC impedance measurements show that the initial composition with x = 0.10, y = 0.10 possesses the highest ionic conductivity of 1.65 × 10^-5 S·cm^-1 at room temperature, while the sample with initial composition of x =0.20, y =0.10 has the best ionic conductivity of 6. 53 × 10^-3S·cm^-1 at 573 K and decomposes at 3.0 V.展开更多
NBI fast ion losses in the presence of the toroidal field ripple on EAST have been investigated by using the orbit code GYCAVA and the NBI code TGCO.The ripple effect was included in the upgraded version of the GYCAVA...NBI fast ion losses in the presence of the toroidal field ripple on EAST have been investigated by using the orbit code GYCAVA and the NBI code TGCO.The ripple effect was included in the upgraded version of the GYCAVA code.It is found that loss regions of NBI fast ions are mainly on the low field side near the edge in the presence of ripple.For co-current NBIs,the synergy effect of ripple and Coulomb collision on fast ion losses is dominant,and fast trapped ions located on the low field side are easily lost.The ripple well loss and the ripple stochastic loss of fast ions have been identified from the heat loads of co-current NBI fast ions.The ripple stochastic loss and the collisioninduced loss are much larger than the ripple well loss.Heat loads of lost fast ions are mainly localized on the right side of the radio frequency wave antennas from the inside view toward the first wall.For counter-current NBIs,the first orbit loss due to the magnetic drift is the dominant loss channel.In addition,fast ion loss fraction with ripple and collision for each NBI linearly increases with the effective charge number,which is related to the pitch angle scattering effect.展开更多
Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate(EC),propylene carbonate(PC),and ethyl methyl carbonate(EMC) are the most commonly used electrolyte materials in commercial re...Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate(EC),propylene carbonate(PC),and ethyl methyl carbonate(EMC) are the most commonly used electrolyte materials in commercial rechargeable lithium batteries(LIBs) due to their outstanding dissociation ability to lithium salts.However,volatility and fluidity result in their inevitable demerits like leakage and potential safety problem of the final LIBs.Here we for the first time device a subtle method to prepare a novel thermal-stable and non-fluid poly(carbonate) solid-state electrolyte to merge EC with lithium carriers.To this aim,a series of carbonate substituted imidazole ionic plastic crystals(G-NTOC) with different polymerization degrees have been synthesized.The resulting G-NTOC shows an excellent solid-state temperature window(R.T.-115℃).More importantly,the maximum ionic conductivity and lithium transference number of the prepared G-NTOC reach 0.36 × 10^(-3) S cm^(-1) and 0.523 at 30℃,respectively.Galvanostatic cycling test results reveal that the developed G-NTOC solid-state electrolytes are favorable to restraining the growth of lithium dendrite due to the excellent compatibility between the electrode and the produced plastic crystal electrolyte.The fabricated LiIG-NTOCILiFeP04 all-solid-state cell initially delivers a maximum discharge capacity of 152.1 mAh g^(-1) at the discharge rate of 0.1 C.After chargingdischarging the cell for 60 times,Coulombic efficiency of the solid-state cell still exceeds 97%.Notably,the LiIG-NTOCILiFeP04 cell can stably light a commercial LED with a rated power of 0.06 W for more than1 h at 30℃,and the output power nearly maintains unchanged with the charging-discharging cycling test,implying a sizeable potential application in the next generation of solid-state LIBs.展开更多
Perovskite type lithium fast ion conductors of Li 3 x La 0.67- x In y Ti 1-2 y P y O 3 system were prepared by solid state reaction. X ray powder diffraction shows that perovskite solid...Perovskite type lithium fast ion conductors of Li 3 x La 0.67- x In y Ti 1-2 y P y O 3 system were prepared by solid state reaction. X ray powder diffraction shows that perovskite solid solution forms in the ranges of x =0.10～0.12, y ≤0.2. AC impedance measurements indicate that the bulk conductivities and the total conductivities are of 1×10 -4 and 1× 10 -5 S·cm -1 at 25 ℃ respectively. The compositions have low bulk activation energies of 20 kJ·mol -1 in the temperature ranges of 298～523 K and total activation energies of 40 kJ·mol -1 in the temperature ranges of 298～623 K.展开更多
Natural layered aluminosilicate Kaolinite Al 4[Si 4O 10 ](OH) 8 has been used as a starting material for preparing a new system of lithium fast ion conductors by high temperature(1073—1223 K) solid state react...Natural layered aluminosilicate Kaolinite Al 4[Si 4O 10 ](OH) 8 has been used as a starting material for preparing a new system of lithium fast ion conductors by high temperature(1073—1223 K) solid state reactions. X ray powder diffraction and a.c. impedance technique were used to characterize the compositions of the Li 1+2 x Al x Zr 2- x Si x P 3- x O 12 system. A single pure solid solution phase with R3c space group can be formed in the composition range of x ≤0 4. A specimen with x =0 3 possesses a maximum ionic conductivity which reaches up to 1 03×10 -2 s/cm at 723 K and the activation energy is 29 63 kJ/mol.展开更多
Ion cyclotron resonance heating(ICRH),which can produce fast ions,is an important auxiliary heating method at EAST.To analyze the effect of ICRH-induced fast ions on the plasma pressure at EAST,simulations are perform...Ion cyclotron resonance heating(ICRH),which can produce fast ions,is an important auxiliary heating method at EAST.To analyze the effect of ICRH-induced fast ions on the plasma pressure at EAST,simulations are performed using TRANSP and TORIC codes.It is found that the ICRF-induced fast ion pressure cannot be negligible when the ICRF power is sufficiently high.The magnitude of the total ion pressure can be raised up to 60%of the total pressure as the input power rises above 3 MW.The pressure profile is also significantly modified when the resonant layer is changed.It is shown that by changing the wave frequency and antenna position,the total ion pressure profile can be broadened,which might provide an option for profile control at EAST.展开更多
Understanding and modeling fast-ion stabilization of ion-temperature-gradient(ITG)driven microturbulence have profound implications for designing and optimizing future fusion reactors.In this work,an analytic model is...Understanding and modeling fast-ion stabilization of ion-temperature-gradient(ITG)driven microturbulence have profound implications for designing and optimizing future fusion reactors.In this work,an analytic model is presented,which describes the effect of fast ions on ITG mode.This model is derived from a bounce-average gyro-kinetic equation for trapped fast ions and ballooning transformation for ITG mode.In addition to dilution,strong wave-fast-ion resonant interaction is involved in this model.Based on numerical calculations,the effects of the main physical parameters are studied.The increasing density of fast ions will strengthen the effects of fast ions.The effect of wave-particle resonance strongly depends on the temperature of fast ions.Furthermore,both increasing density gradient and the ratio of the temperature and density gradients can strengthen the stabilization of fast ions in ITG mode.Finally,the influence of resonance broadening of wave-particle interaction is discussed.展开更多
The classical prompt loss of fast ions produced by minority ion cyclotron resonance heating(ICRH)is studied by a guiding center orbit following code in the Experimental Advanced Superconducting Tokamak(EAST).It is fou...The classical prompt loss of fast ions produced by minority ion cyclotron resonance heating(ICRH)is studied by a guiding center orbit following code in the Experimental Advanced Superconducting Tokamak(EAST).It is found that the loss of fast ions produced by ICRH mainly appears in both ends of the resonance layer,while the loss of fast ions in the middle resonance layer is very small.The dominant fast loss comes from trapped ions,rather than from passing ions.Controlling the location of resonance layer at the plasma core may be more beneficial to the EAST tokamak ICRH.In addition,the loss distribution of fast ions is studied.The results show that the fast ions are mainly lost near the midplane in the poloidal direction,but almost uniformly in the toroidal direction.Moreover,we investigate the dependence of fast ion loss on the ICRH power.The simulation results show that the loss fraction of fast ions in both ends of the resonance region increases with the ion cyclotron range of frequencies(ICRF)power,but barely affects the loss of fast ions in the middle region.展开更多
The absorption of neutral beam power and the fast ion stored energy in EAST plasmas with neutral beam injection(NBI)is analyzed to improve the calculation of thermal energy confinement time.The neutral beam power abso...The absorption of neutral beam power and the fast ion stored energy in EAST plasmas with neutral beam injection(NBI)is analyzed to improve the calculation of thermal energy confinement time.The neutral beam power absorption and fast ion stored energy are systematically calculated using the TRANSP code,through the investigation of global parameters including plasma current,line averaged density and beam energy.Results have shown that scaling laws for the NBI absorption coefficient and fast ion energy rate are obtained through statistical analysis.A comparison of the confinement improvement factor H98y2 with these new scaling laws against those assuming fixed coefficients is given.展开更多
Beam-ion losses induced by fast-ion-driven toroidal Alfven eigenmodes （TAE） were measured with a scintillator-based lost fast-ion probe （SLIP） in the large helical device （LHD）. The SLIP gave simultaneously the ...Beam-ion losses induced by fast-ion-driven toroidal Alfven eigenmodes （TAE） were measured with a scintillator-based lost fast-ion probe （SLIP） in the large helical device （LHD）. The SLIP gave simultaneously the energy E and the pitch angle X=arccos（v///v） distribution of the lost fast ions. The loss fluxes were investigated for three typical magnetic configurations of Rax-vac=3.60 m, 3.75 m. and 3.90 m, where Rax-vac is the magnetic axis position of the vacuum field. Dominant losses induced by TAEs in these three configurations were observed in the E/X regions of 50-190 keV/40°, 40-170 keV/25°, and 30-190 keV/30°, respectively. Lost-ion fluxes induced by TAEs depend clearly on the amplitude of TAE magnetic fluctuations, Rax-vac and the toroidal field strength Bt. The increment of the loss fluxes has the dependence of （bTAE/Bt）s. The power s increases from s = 1 to 3 with the increase of the magnetic axis position in finite beta plasmas.展开更多
The neutral beam injection is widely adopted in tokamaks as a key heating tool,playing a crucial role in generating burning plasmas.However,the loss of beam ions can damage the first wall and reduce the heating effici...The neutral beam injection is widely adopted in tokamaks as a key heating tool,playing a crucial role in generating burning plasmas.However,the loss of beam ions can damage the first wall and reduce the heating efficiency,resulting in failure to maintain steady-state conditions.In this work,the effect of neutral particles in the edge on fast ions generated by NBI in the Experimental Advanced Superconducting Tokamak(EAST)device is studied using the particle tracer code(PTC).The poloidal distribution of neutral particles is calculated by edge plasma simulation code SOLPS-ITER.In this simulation,four beam lines in EAST are considered:co-current tangential(co-tang),co-current perpendicular(co-perp),counter-current tangential(ctr-tang)and counter-current perpendicular(ctr-perp).It is shown that,in the absence of neutral particles,the loss fraction of ctr-injection is considerably higher than that of the co-injection.When considering the neutral particles,it is found that the ctr-perp injection demonstrates a significant variation in particles loss fraction(ranging from 18.56%to 25.42%)compared to the other three injection configurations.In terms of the loss fraction induced by neutral particles,ctr-injection exceeds co-injection,and perpendicular configuration exceeds tangential configuration.Furthermore,the difference of charge exchange ratios of three different energy(full energy,half energy,one third energy)of the four injections can be attributed to variations in the poloidal trajectories associated with each of these injections.Moreover,approximately half of fast ions which undergo neutralization directly lose to the first wall while the rest re-enter the bulk plasma and re-ionize.Except for the ctr-tang injection,the reionization ions from the other three injections exhibit effective confinement.展开更多
2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha(FIDA)measurements on experimental advanced superconducting tokamak(EAST).To make up for the sparse data and incomplete ve...2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha(FIDA)measurements on experimental advanced superconducting tokamak(EAST).To make up for the sparse data and incomplete velocity-space coverage with the dual-view,we use nonnegativity and null-measurements as prior information to reconstruct the velocity distribution in experiments with co-and counter-current neutral beam injection.An improved reconstructed fast-ion distribution is achieved by combining the existing O-and B-port FIDA measurements with the proposed A-port FIDA view.To further improve the reliability of FIDA-based reconstructions on EAST,based on real multi-view FIDA measurements on EAST in the near future,various bases will be studied further.展开更多
Fast ion conductor materials screening based on high-throughput calculations involves enormous computing tasks.The process usually includes structural optimization,energy calculation,charge analysis and ionic migratio...Fast ion conductor materials screening based on high-throughput calculations involves enormous computing tasks.The process usually includes structural optimization,energy calculation,charge analysis and ionic migration performance estimation.The first one involves looking for the equilibrium atomic positions in huge amount of candidate compounds or derivative structures,and the computational cost is always high because of the task-intensive features.The last one relates to the kinetic problems,for which the time-consuming transition state theory and the molecular dynamics are the main simulation methods.In this work,two predictive models,ionic migration activation energy model and structural optimization model,are developed based on machine learning(ML)techniques to accelerate the process of estimating activation energy and relaxing the doped crystal structures,respectively.By training 3136 energy barrier data calculated by bond valence(BV)method,an ionic migration activation energy model(Ea model)with mean absolute error(MAE)of 0.26 eV on testing data set is obtained.We apply this model and filter LiBiOS as a promising fast Li^(+)conductor from 49 Licontaining hetero-anionic compounds.Although the model-predicted result shows relatively low energy barrier,further analysis indicates that the high carrier formation energy restricts the ionic transportability.Therefore,we substitute fractional Li^(+)with Mg^(2+)in LiBiOS to relieve the large difficulty of forming carriers in the structure.In order to fast explore the optimal doping scheme,we develop the structural optimization model(E-f model)containing the ML-based energy and force prediction to accelerate the structural optimization under various LieMg ratio and doping configurations.Decent doping scheme Li_(1-2x)Mg_(x)BiOS(x=0.1875)shows much better Li^(+)migration performance compared with LiBiOS without substitution.This method of screening fast ion conductor materials and finding optimal doping scheme will extremely accelerate materials explorations.展开更多
A fully kinetic particle-in-cell/Monte Carlo model is employed to self-consistently study the effects of fast-ion injection on sheath potential and electric field profile in collisional magnetized plasma with a floati...A fully kinetic particle-in-cell/Monte Carlo model is employed to self-consistently study the effects of fast-ion injection on sheath potential and electric field profile in collisional magnetized plasma with a floating absorbing wall. The influences of the fast-ion injection velocity and density, the magnetic field and angle t^0 formed by the magnetic field and the x-axis on the sheath potential and electric field are discussed in detail. Numerical results show that increasing fast-ion injection density or decreasing injection velocity can enhance the potential drop and electric field in the sheath. Also, increasing the magnetic field strength can weaken the loss of charged particles to the wall and thus decrease the potential and electric field in the sheath. The time evolution of ion flux and velocity distribution on the wall is found to be significantly affected by the magnetic field.展开更多
The turbulence characteristics of plasmas with internal transport barriers in the HL-2A tokamak are analyzed by means of linear gyrokinetic simulations. It is found that turbulence is dominated by the ion temperature ...The turbulence characteristics of plasmas with internal transport barriers in the HL-2A tokamak are analyzed by means of linear gyrokinetic simulations. It is found that turbulence is dominated by the ion temperature gradient(ITG)mode together with large-scale modes characterized by high-frequency electromagnetic fluctuation, which are destabilized by the steep ion temperature gradient in the weak magnetic shear regime. Comparison with solutions of analytical dispersion relations shows that their linear features match well with the beta-induced Alfvén eigenmode branch of the shear Alfvénic spectrum. It is further clarified that the large population of fast ions in these plasmas plays a stabilization role through the dilution mechanism in high-n ITG mode regimes.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2022YFE03060002,2019YFE03090100)by the Innovation Program of Southwestern Institute of Physics(No.202001XWCXRC001)partly supported by the Youth Science and Technology Innovation Team of Sichuan Province(No.2022JDTD0003)。
文摘Transport of fast ions is a crucial issue during the operation of ITER.Redistribution of neutral beam injection(NBI)fast ions by the ideal internal magnetohydrodynamic(MHD)instabilities in ITER is studied utilizing the guiding-center code ORBIT(White R B and Chance M S 1984Phys.Fluids 272455).Effects of the perturbation amplitude A of the internal kink,the perturbation frequency f of the fishbone instability,and the toroidal mode number n of the internal kink are investigated,respectively,in this work.The n=1 internal kink mode can cause NBI fast ions transporting in real space from regions of 0<s≤0.32 to 0.32<s≤0.53,where s labels the normalized plasma radial coordinate.The transport of fast ions is greater as the perturbation amplitude increases.The maximum relative change of the number of fast ions approaches 5%when the perturbation amplitude rises to 500 G.A strong transport is generated between the regions of 0<s≤0.05 and 0.05<s≤0.12 in the presence of the fishbone instability.Higher frequency results in greater transport,and the number of fast ions in 0<s≤0.05 is reduced by 30%at the fishbone frequency of 100 k Hz.Perturbations with higher n will lead to the excursion of fast ion transport regions outward along the radial direction.The loss of fast ions,however,is not affected by the internal MHD perturbation.Strong transport from 0<s≤0.05 to 0.05<s≤0.12 does not influence the plasma heating power of ITER,since the NBI fast ions are still located in the plasma core.On the other hand,the influence of fast ion transport from 0<s≤0.32 to 0.32<s≤0.53 needs further study.
基金supported by the National MCF Energy R&D Program of China(No.2019YFE03020003)partly supported by the Key Research and Development Program of Hubei Province(No.2021BAA167)National Natural Science Foundation of China(No.51821005)。
文摘As a promising method for fast ion diagnostics,collective Thomson scattering(CTS)can measure the one-dimensional velocity distribution of fast ions with high spatial and temporal resolution.The feasibility of diagnosing fast ions in a compact high-field tokamak by CTS was studied in this work,and the results showed that a wide range of probing frequencies could be applied.A high-frequency case and a low-frequency case were mainly considered for fast ion diagnostics in a compact high-field tokamak.The use of a high probing frequency could effectively avoid the refraction effect of the beams,while the application of a low probing frequency allows greater flexibility in the selection of scattering angle which may help to improve the spatial resolution.Based on typical plasma conditions(B_(0)=12.2 T,n_(e0)=4.3×10^(20)m^(-3),T_(e0)=22.2 keV,T_(i0)=19.8 keV)for a compact high-field tokamak,a220 GHz CTS diagnostic that utilizes a small scattering angle ofθ=30°and a 160 GHz CTS diagnostic that utilizes an orthogonal geometry were proposed.Further study showed that the high-frequency case could operate in a wider range of plasma conditions and provide more information on fast ions while the low-frequency case could achieve higher spatial resolution of the poloidal direction.
基金financially supported by the National Natural Science Foundation of China(51901249,U1904216)。
文摘Although aqueous zinc ion hybrid capacitors have advantageous integration of batteries and supercapacitors,they still suffer from the inherent problems of dendrite growth and interfacial side reactions on Zn anodes.Herein,a universal fast zinc-ion diffusion layer on a three-dimensional(3 D)mesh structure model is demonstrated to effectively improve Zn plating/stripping reversibility.The fast ion diffusion alloy layer accelerates the Zn^(2+)migration in an orderly manner to homogenize Zn^(2+)flux and overcomes the defects of the commercial mesh substrate,effectively avoiding dendrite growth and side reactions.Consequently,the proof-of-concept silver-zinc alloy modified stainless steel mesh delivers superb reversibility with the high coulombic efficiency over 99.4%at 4 mA cm^(-2)after 1600 cycles and excellent reliability of over 830 h at 1 mA cm^(-2),Its feasibility is also evidenced in commercial zinc ion hybrid capacitors with activated carbon as the cathode.This work enriches the fundamental comprehension of fast zinc-ion diffusion layer combined with a 3 D substrate on the Zn deposition and opens a universal approach to design advanced host for Zn electrodes in zinc ion hybrid capacitors.
基金Project supported by the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(NSFC Grant No.11261140328)
文摘A peculiar first orbit loss type was found apart from the normal ones when we use ORBIT code to simulate fast ion orbits in the EAST tokamak. Fast ion orbits were studied in the presence of toroidal field （TF） ripple and magnetohydro- dynamic （MHD） perturbations. We analyzed the properties of the drifted orbits in detail and compared their differences, finding that the combined effects of ripple and magnetic islands are much greater than the effects of either one of them alone. Then we investigated the orbitdeviations as a function of pitch angle in different radial positions. The modeling results demonstrate that the loss of trapped particles is mainly caused by the ripple, while MHD＇perturbation mainly plays an important role in the passing particles. Furthermore we modeled the loss rate using different equilibriums. Results prove that a higher beta can indeed improve the confinement of fast ions, while a little change in the q profile can make the topologies of magnetic islands become quite different and results in quite different total particle losses.
文摘New lithium fast ion conductors of Li1.2 ＋ x - y Yx Ti1.9 - x Al0.1Si0. 1Wy P2.9 - y O12 based on LiTi2（PO4）3 were prepared by high temperature solid state reaction using refined natural kaolinite as a starting material. X-ray powder diffraction analysis indicates that a phase with Nasieon-like structure exists together with other phases in the composition range of x =0.1, y≤0.2 and x =0.2,y ≤0.2. AC impedance measurements show that the initial composition with x = 0.10, y = 0.10 possesses the highest ionic conductivity of 1.65 × 10^-5 S·cm^-1 at room temperature, while the sample with initial composition of x =0.20, y =0.10 has the best ionic conductivity of 6. 53 × 10^-3S·cm^-1 at 573 K and decomposes at 3.0 V.
基金supported by National Natural Science Foundation of China(No.11775265)。
文摘NBI fast ion losses in the presence of the toroidal field ripple on EAST have been investigated by using the orbit code GYCAVA and the NBI code TGCO.The ripple effect was included in the upgraded version of the GYCAVA code.It is found that loss regions of NBI fast ions are mainly on the low field side near the edge in the presence of ripple.For co-current NBIs,the synergy effect of ripple and Coulomb collision on fast ion losses is dominant,and fast trapped ions located on the low field side are easily lost.The ripple well loss and the ripple stochastic loss of fast ions have been identified from the heat loads of co-current NBI fast ions.The ripple stochastic loss and the collisioninduced loss are much larger than the ripple well loss.Heat loads of lost fast ions are mainly localized on the right side of the radio frequency wave antennas from the inside view toward the first wall.For counter-current NBIs,the first orbit loss due to the magnetic drift is the dominant loss channel.In addition,fast ion loss fraction with ripple and collision for each NBI linearly increases with the effective charge number,which is related to the pitch angle scattering effect.
基金the financial support of the National Natural Science Foundation of China (21961044, 22169024)the Yunnan University’s Research Innovation Fund for graduate students (2021Y394)。
文摘Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate(EC),propylene carbonate(PC),and ethyl methyl carbonate(EMC) are the most commonly used electrolyte materials in commercial rechargeable lithium batteries(LIBs) due to their outstanding dissociation ability to lithium salts.However,volatility and fluidity result in their inevitable demerits like leakage and potential safety problem of the final LIBs.Here we for the first time device a subtle method to prepare a novel thermal-stable and non-fluid poly(carbonate) solid-state electrolyte to merge EC with lithium carriers.To this aim,a series of carbonate substituted imidazole ionic plastic crystals(G-NTOC) with different polymerization degrees have been synthesized.The resulting G-NTOC shows an excellent solid-state temperature window(R.T.-115℃).More importantly,the maximum ionic conductivity and lithium transference number of the prepared G-NTOC reach 0.36 × 10^(-3) S cm^(-1) and 0.523 at 30℃,respectively.Galvanostatic cycling test results reveal that the developed G-NTOC solid-state electrolytes are favorable to restraining the growth of lithium dendrite due to the excellent compatibility between the electrode and the produced plastic crystal electrolyte.The fabricated LiIG-NTOCILiFeP04 all-solid-state cell initially delivers a maximum discharge capacity of 152.1 mAh g^(-1) at the discharge rate of 0.1 C.After chargingdischarging the cell for 60 times,Coulombic efficiency of the solid-state cell still exceeds 97%.Notably,the LiIG-NTOCILiFeP04 cell can stably light a commercial LED with a rated power of 0.06 W for more than1 h at 30℃,and the output power nearly maintains unchanged with the charging-discharging cycling test,implying a sizeable potential application in the next generation of solid-state LIBs.
文摘Perovskite type lithium fast ion conductors of Li 3 x La 0.67- x In y Ti 1-2 y P y O 3 system were prepared by solid state reaction. X ray powder diffraction shows that perovskite solid solution forms in the ranges of x =0.10～0.12, y ≤0.2. AC impedance measurements indicate that the bulk conductivities and the total conductivities are of 1×10 -4 and 1× 10 -5 S·cm -1 at 25 ℃ respectively. The compositions have low bulk activation energies of 20 kJ·mol -1 in the temperature ranges of 298～523 K and total activation energies of 40 kJ·mol -1 in the temperature ranges of 298～623 K.
文摘Natural layered aluminosilicate Kaolinite Al 4[Si 4O 10 ](OH) 8 has been used as a starting material for preparing a new system of lithium fast ion conductors by high temperature(1073—1223 K) solid state reactions. X ray powder diffraction and a.c. impedance technique were used to characterize the compositions of the Li 1+2 x Al x Zr 2- x Si x P 3- x O 12 system. A single pure solid solution phase with R3c space group can be formed in the composition range of x ≤0 4. A specimen with x =0 3 possesses a maximum ionic conductivity which reaches up to 1 03×10 -2 s/cm at 723 K and the activation energy is 29 63 kJ/mol.
基金The authors would like to thank Doctors Guosheng Xu,Damao Yao,and Yongliang Li for helpful discussionsThis work was supported by the National Key R&D Program of China(Nos.2017YFE0300400,2017YFE0300406)National Natural Science Foundation of China(Nos.11575239,11775265).
文摘Ion cyclotron resonance heating(ICRH),which can produce fast ions,is an important auxiliary heating method at EAST.To analyze the effect of ICRH-induced fast ions on the plasma pressure at EAST,simulations are performed using TRANSP and TORIC codes.It is found that the ICRF-induced fast ion pressure cannot be negligible when the ICRF power is sufficiently high.The magnitude of the total ion pressure can be raised up to 60%of the total pressure as the input power rises above 3 MW.The pressure profile is also significantly modified when the resonant layer is changed.It is shown that by changing the wave frequency and antenna position,the total ion pressure profile can be broadened,which might provide an option for profile control at EAST.
基金National Natural Science Foundation of China(Nos.11822505,11835016 and 11675257)the Youth Innovation Promotion Association CAS,the Users with Excellence Program of Hefei Science Center CAS(No.2019HSC-UE013)+1 种基金the Fundamental Research Funds for the Central Universities(No.WK3420000008)the Collaborative Innovation Program of Hefei Science Center CAS(No.2019HSC-CIP014)。
文摘Understanding and modeling fast-ion stabilization of ion-temperature-gradient(ITG)driven microturbulence have profound implications for designing and optimizing future fusion reactors.In this work,an analytic model is presented,which describes the effect of fast ions on ITG mode.This model is derived from a bounce-average gyro-kinetic equation for trapped fast ions and ballooning transformation for ITG mode.In addition to dilution,strong wave-fast-ion resonant interaction is involved in this model.Based on numerical calculations,the effects of the main physical parameters are studied.The increasing density of fast ions will strengthen the effects of fast ions.The effect of wave-particle resonance strongly depends on the temperature of fast ions.Furthermore,both increasing density gradient and the ratio of the temperature and density gradients can strengthen the stabilization of fast ions in ITG mode.Finally,the influence of resonance broadening of wave-particle interaction is discussed.
基金supported by National Natural Science Foundation of China (No. 11805239)the Natural Science Foundation of Hunan Province (No. 2019JJ50011)
文摘The classical prompt loss of fast ions produced by minority ion cyclotron resonance heating(ICRH)is studied by a guiding center orbit following code in the Experimental Advanced Superconducting Tokamak(EAST).It is found that the loss of fast ions produced by ICRH mainly appears in both ends of the resonance layer,while the loss of fast ions in the middle resonance layer is very small.The dominant fast loss comes from trapped ions,rather than from passing ions.Controlling the location of resonance layer at the plasma core may be more beneficial to the EAST tokamak ICRH.In addition,the loss distribution of fast ions is studied.The results show that the fast ions are mainly lost near the midplane in the poloidal direction,but almost uniformly in the toroidal direction.Moreover,we investigate the dependence of fast ion loss on the ICRH power.The simulation results show that the loss fraction of fast ions in both ends of the resonance region increases with the ion cyclotron range of frequencies(ICRF)power,but barely affects the loss of fast ions in the middle region.
基金Numerical computations were performed on the ShenMa High Performance Computing Cluster in Institute of Plasma Physics,Chinese Academy of SciencesThe work is supported by National MCF Energy R&D Program of China(Nos.2018YFE0302100,2017YFE0301100)+1 种基金National Natural Science Foundation of China(Nos.11775262,11975274,11805237,11705239)the National Magnetic Confinement Fusion Science Program of China(No.2015GB102000).
文摘The absorption of neutral beam power and the fast ion stored energy in EAST plasmas with neutral beam injection(NBI)is analyzed to improve the calculation of thermal energy confinement time.The neutral beam power absorption and fast ion stored energy are systematically calculated using the TRANSP code,through the investigation of global parameters including plasma current,line averaged density and beam energy.Results have shown that scaling laws for the NBI absorption coefficient and fast ion energy rate are obtained through statistical analysis.A comparison of the confinement improvement factor H98y2 with these new scaling laws against those assuming fixed coefficients is given.
基金supported in part by the Grant-in-Aid for Scientific Research from MEXT (No. 16082209)from JSPS (Nos. 21360457, 21340175,and 22-7912)+1 种基金the LHD project budget (NIFS09ULHH508)partially supported by the JSPS-CAS Core-University program in thefield of‘Plasma and Nuclear Fusion’
文摘Beam-ion losses induced by fast-ion-driven toroidal Alfven eigenmodes （TAE） were measured with a scintillator-based lost fast-ion probe （SLIP） in the large helical device （LHD）. The SLIP gave simultaneously the energy E and the pitch angle X=arccos（v///v） distribution of the lost fast ions. The loss fluxes were investigated for three typical magnetic configurations of Rax-vac=3.60 m, 3.75 m. and 3.90 m, where Rax-vac is the magnetic axis position of the vacuum field. Dominant losses induced by TAEs in these three configurations were observed in the E/X regions of 50-190 keV/40°, 40-170 keV/25°, and 30-190 keV/30°, respectively. Lost-ion fluxes induced by TAEs depend clearly on the amplitude of TAE magnetic fluctuations, Rax-vac and the toroidal field strength Bt. The increment of the loss fluxes has the dependence of （bTAE/Bt）s. The power s increases from s = 1 to 3 with the increase of the magnetic axis position in finite beta plasmas.
基金supported by the National Key R&D Program of China(No.2022YFE03090000)National Natural Science Foundation of China(No.11975068).
文摘The neutral beam injection is widely adopted in tokamaks as a key heating tool,playing a crucial role in generating burning plasmas.However,the loss of beam ions can damage the first wall and reduce the heating efficiency,resulting in failure to maintain steady-state conditions.In this work,the effect of neutral particles in the edge on fast ions generated by NBI in the Experimental Advanced Superconducting Tokamak(EAST)device is studied using the particle tracer code(PTC).The poloidal distribution of neutral particles is calculated by edge plasma simulation code SOLPS-ITER.In this simulation,four beam lines in EAST are considered:co-current tangential(co-tang),co-current perpendicular(co-perp),counter-current tangential(ctr-tang)and counter-current perpendicular(ctr-perp).It is shown that,in the absence of neutral particles,the loss fraction of ctr-injection is considerably higher than that of the co-injection.When considering the neutral particles,it is found that the ctr-perp injection demonstrates a significant variation in particles loss fraction(ranging from 18.56%to 25.42%)compared to the other three injection configurations.In terms of the loss fraction induced by neutral particles,ctr-injection exceeds co-injection,and perpendicular configuration exceeds tangential configuration.Furthermore,the difference of charge exchange ratios of three different energy(full energy,half energy,one third energy)of the four injections can be attributed to variations in the poloidal trajectories associated with each of these injections.Moreover,approximately half of fast ions which undergo neutralization directly lose to the first wall while the rest re-enter the bulk plasma and re-ionize.Except for the ctr-tang injection,the reionization ions from the other three injections exhibit effective confinement.
基金supported by National Natural Science Foundation of China(No.11975276)Anhui Provincial Natural Science Foundation(No.2008085J04)+3 种基金Anhui Provincial Key R&D Programmes(No.202104b11020003)the National Key Research and Development Program of China(No.2019YFE03020004)the Excellence Program of Hefei Science Center CAS(No.2021HSC-UE015)。
文摘2D fast-ion velocity-space distributions have been reconstructed from two-view fast-ion D-alpha(FIDA)measurements on experimental advanced superconducting tokamak(EAST).To make up for the sparse data and incomplete velocity-space coverage with the dual-view,we use nonnegativity and null-measurements as prior information to reconstruct the velocity distribution in experiments with co-and counter-current neutral beam injection.An improved reconstructed fast-ion distribution is achieved by combining the existing O-and B-port FIDA measurements with the proposed A-port FIDA view.To further improve the reliability of FIDA-based reconstructions on EAST,based on real multi-view FIDA measurements on EAST in the near future,various bases will be studied further.
基金We acknowledge the National Natural Science Foundation of China(grant number 52022106)SAMSUNG Research China for financial support and idea explorationwell as Tianjin Supercomputer Center for providing computing resources.
文摘Fast ion conductor materials screening based on high-throughput calculations involves enormous computing tasks.The process usually includes structural optimization,energy calculation,charge analysis and ionic migration performance estimation.The first one involves looking for the equilibrium atomic positions in huge amount of candidate compounds or derivative structures,and the computational cost is always high because of the task-intensive features.The last one relates to the kinetic problems,for which the time-consuming transition state theory and the molecular dynamics are the main simulation methods.In this work,two predictive models,ionic migration activation energy model and structural optimization model,are developed based on machine learning(ML)techniques to accelerate the process of estimating activation energy and relaxing the doped crystal structures,respectively.By training 3136 energy barrier data calculated by bond valence(BV)method,an ionic migration activation energy model(Ea model)with mean absolute error(MAE)of 0.26 eV on testing data set is obtained.We apply this model and filter LiBiOS as a promising fast Li^(+)conductor from 49 Licontaining hetero-anionic compounds.Although the model-predicted result shows relatively low energy barrier,further analysis indicates that the high carrier formation energy restricts the ionic transportability.Therefore,we substitute fractional Li^(+)with Mg^(2+)in LiBiOS to relieve the large difficulty of forming carriers in the structure.In order to fast explore the optimal doping scheme,we develop the structural optimization model(E-f model)containing the ML-based energy and force prediction to accelerate the structural optimization under various LieMg ratio and doping configurations.Decent doping scheme Li_(1-2x)Mg_(x)BiOS(x=0.1875)shows much better Li^(+)migration performance compared with LiBiOS without substitution.This method of screening fast ion conductor materials and finding optimal doping scheme will extremely accelerate materials explorations.
基金supported by the National Basic Research Program of China (Nos. 2010CB832901, 2008CB717801)the Fundamental Research Funds for the Central Universities (No. DUT10ZD111)the Program for New Century Excellent Talents in University (NCET-08-0073)
文摘A fully kinetic particle-in-cell/Monte Carlo model is employed to self-consistently study the effects of fast-ion injection on sheath potential and electric field profile in collisional magnetized plasma with a floating absorbing wall. The influences of the fast-ion injection velocity and density, the magnetic field and angle t^0 formed by the magnetic field and the x-axis on the sheath potential and electric field are discussed in detail. Numerical results show that increasing fast-ion injection density or decreasing injection velocity can enhance the potential drop and electric field in the sheath. Also, increasing the magnetic field strength can weaken the loss of charged particles to the wall and thus decrease the potential and electric field in the sheath. The time evolution of ion flux and velocity distribution on the wall is found to be significantly affected by the magnetic field.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFE0301201)partially by the National Natural Science Foundation of China (Grant Nos. U1967206 and 11775069)。
文摘The turbulence characteristics of plasmas with internal transport barriers in the HL-2A tokamak are analyzed by means of linear gyrokinetic simulations. It is found that turbulence is dominated by the ion temperature gradient(ITG)mode together with large-scale modes characterized by high-frequency electromagnetic fluctuation, which are destabilized by the steep ion temperature gradient in the weak magnetic shear regime. Comparison with solutions of analytical dispersion relations shows that their linear features match well with the beta-induced Alfvén eigenmode branch of the shear Alfvénic spectrum. It is further clarified that the large population of fast ions in these plasmas plays a stabilization role through the dilution mechanism in high-n ITG mode regimes.
