利用蒙特卡罗方法,模拟计算了不同线性能量传输(liner energy transfer,LET)的重离子在碳化硅中的能量损失,模拟结果表明:重离子在碳化硅中单位深度的能量损失受离子能量和入射深度共同影响;能量损失主要由初级重离子和次级电子产生,非...利用蒙特卡罗方法,模拟计算了不同线性能量传输(liner energy transfer,LET)的重离子在碳化硅中的能量损失,模拟结果表明:重离子在碳化硅中单位深度的能量损失受离子能量和入射深度共同影响;能量损失主要由初级重离子和次级电子产生,非电离能量损失只占总能量损失的1%左右;随着LET的增大,次级电子的初始角度和能量分布越来越集中;重离子诱导产生的电荷沉积峰值位置在重离子径迹中心,在垂直于入射深度方向上呈高斯线性减小分布.利用锎源进行碳化硅MOSFET单粒子烧毁试验,结合TCAD模拟得到不同漏极电压下器件内部电场分布,在考虑电场作用的蒙特卡罗模拟中发现:碳化硅MOSFET外延层的电场强度越大,重离子受电场作用在外延层运动的路径越长、沉积能量越多,次级电子越容易偏向电场方向运动导致局部能量沉积过高.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
A mechanism for energy transfer from the solar wind to the Martian ionosphere through open magnetic flux rope is proposed based on the observations by Mars Atmosphere and Volatile EvolutioN(MAVEN).The satellite was lo...A mechanism for energy transfer from the solar wind to the Martian ionosphere through open magnetic flux rope is proposed based on the observations by Mars Atmosphere and Volatile EvolutioN(MAVEN).The satellite was located in the dayside magnetosheath at an altitude of about 70o km above the northern hemisphere.Collisions between the hot solar wind protons and the cold heavy ions/neutrals in the subsolar region can cool the protons and heat the heavy ions.As a result,the magnetosheath protons are siphoned into the ionosphere due to the thermal pressure gradient of protons and the heated heavy ions escape along the open magnetic field lines.Although direct collisions in the lower-altitude region were not detected,this physical process is demonstrated by MAVEN measurements of enhanced proton density,decreased proton temperature and oppositely directed motions of hot and cool protons within the flux rope,which are very different from the observational features of the flux transfer events near the Earth's magnetopause.This mechanism could universally exist in many contexts where a collisionless plasma region is connected to a collisional plasma region.By reconstructing the magnetic geometry and the cross-section of the flux rope using the Grad-Shafranov technique,the ion loss rates are quantitatively estimated to be on the order of 1023 s-l,which is much higher than previously estimated.展开更多
A spray-drying assisted solid-state method to prepare spherical layer-structured H_(2)TiO_(3) ion sieve(LSTIS)particles is reported herein.The effects of synthesis parameters(calcination temperature,calcination time,a...A spray-drying assisted solid-state method to prepare spherical layer-structured H_(2)TiO_(3) ion sieve(LSTIS)particles is reported herein.The effects of synthesis parameters(calcination temperature,calcination time,and the lithium-titanium molar ratio)on adsorption-desorption performance(the delithiation ratio,titanium dissolution loss,and the adsorption capacity)were investigated.The as-prepared LSTIS exhibited an equilibrium adsorption capacity of 30.08 mg·g^(-1)(average of 25.85 mg·g^(-1) over 5 cycles)and ultra-low titanium dissolution loss of less than 0.12%(average of 0.086%over 5 cycles).The LSTIS showed excellent selectivity toward Li^(+) in Na^(+),K^(+),Mg^(2+),and Ca^(2+) coexisting saline solutions where its adsorption capacity reached 27.45 mg·g^(-1) and the separation factors of Li^(+) over the coexisting cations exceeded 100.The data suggests that the LSTIS is promising to competitively enrich Li^(+) from saline solutions.展开更多
Nonlinear evolution of multiple toroidal Alfven eigenmodes(TAEs) driven by fast ions is self-consistently investigated by kinetic simulations in toroidal plasmas.To clearly identify the effect of nonlinear coupling on...Nonlinear evolution of multiple toroidal Alfven eigenmodes(TAEs) driven by fast ions is self-consistently investigated by kinetic simulations in toroidal plasmas.To clearly identify the effect of nonlinear coupling on the beam ion loss,simulations over single-n modes are also carried out and compared with those over multiple-n modes,and the wave-particle resonance and particle trajectory of lost ions in phase space are analyzed in detail.It is found that in the multiple-n case,the resonance overlap occurs so that the fast ion loss level is rather higher than the sum loss level that represents the summation of loss over all single-n modes in the single-n case.Moreover,increasing fast ion beta β_h can not only significantly increase the loss level in the multiple-n case but also significantly increase the loss level increment between the single-n and multiple-n cases.For example,the loss level in the multiple-n case for β_h=6.0% can even reach 13% of the beam ions and is 44% higher than the sum loss level calculated from all individual single-n modes in the single-n case.On the other hand,when the closely spaced resonance overlap occurs in the multiple-n case,the release of mode energy is increased so that the widely spaced resonances can also take place.In addition,phase space characterization is obtained in both single-n and multiple-n cases.展开更多
A magnetically insulated transmission line （MITL） is used to transmit high power electric pulses in large pulse power systems. However, current loss is unavoidable, especially when the current density is up to 1 MA/...A magnetically insulated transmission line （MITL） is used to transmit high power electric pulses in large pulse power systems. However, current loss is unavoidable, especially when the current density is up to 1 MA/cm. In the paper, the current loss of an MITL made of stainless steel, which is usually used in large pulse power generators, is experimentally studied, and possible mechanisms to explain the current loss of the MITL are analyzed and discussed. From the experimental results, the relationship between loss current density and input current density follows approximately a power law. The loss is also related to the configuration of the MITL.展开更多
铜电解液中的As、Sb、Bi离子含量是影响阴极铜质量的重要因素,现有的电解沉积法电耗高、铜损失量大,萃取方法和离子交换法存在液量大的缺陷。本文利用SO_(2)还原As^(5+)和Sb^(5+)、H_(2)O_(2)氧化As3+和Sb3+调整化合价,促使砷锑铋形成...铜电解液中的As、Sb、Bi离子含量是影响阴极铜质量的重要因素,现有的电解沉积法电耗高、铜损失量大,萃取方法和离子交换法存在液量大的缺陷。本文利用SO_(2)还原As^(5+)和Sb^(5+)、H_(2)O_(2)氧化As3+和Sb3+调整化合价,促使砷锑铋形成沉淀阳极泥的原理,进行了二氧化硫和双氧水并流沉淀方法降低铜电解液中砷锑铋杂质离子的实验研究,结果表明:一定条件下,单独向铜电解液中通入SO_(2)可以降低Sb离子浓度,但As、Bi离子浓度的变化幅度不大;单独向铜电解液中通入H_(2)O_(2)可以降低As、Sb离子浓度,但也会降低Cu、Bi离子浓度,严重时导致阳极钝化;在最佳条件下,H_(2)O_(2)采用滴加方式、加入量为4 m L/L、SO_(2)进气浓度为0.125 g/L、搅拌速度为250 r/min、反应温度为50℃,并流沉淀技术可以实现降低铜电解液中砷锑铋杂质离子的目的,且不会出现阳极钝化现象。展开更多
文摘利用蒙特卡罗方法,模拟计算了不同线性能量传输(liner energy transfer,LET)的重离子在碳化硅中的能量损失,模拟结果表明:重离子在碳化硅中单位深度的能量损失受离子能量和入射深度共同影响;能量损失主要由初级重离子和次级电子产生,非电离能量损失只占总能量损失的1%左右;随着LET的增大,次级电子的初始角度和能量分布越来越集中;重离子诱导产生的电荷沉积峰值位置在重离子径迹中心,在垂直于入射深度方向上呈高斯线性减小分布.利用锎源进行碳化硅MOSFET单粒子烧毁试验,结合TCAD模拟得到不同漏极电压下器件内部电场分布,在考虑电场作用的蒙特卡罗模拟中发现:碳化硅MOSFET外延层的电场强度越大,重离子受电场作用在外延层运动的路径越长、沉积能量越多,次级电子越容易偏向电场方向运动导致局部能量沉积过高.
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National Natural Science Foundation of China(42122061)the Science and Technology Development Fund of Macao SAR(0002/2019/A1)Macao Foundation,and the pre-research project on Civil Aerospace Technologies No.D020308 and D020104 funded by China National Space Administration.C.M.thanks the Austrian Science Fund(FWF):P31521-N27.C.J.F.thanks NASA grant:80NSSC19K1293.A basic version of the Grad-Shafranov reconstruction method in Matlab is available at https://github.com/cmoestl/interplanetarygrad-shafranov.We acknowledge the MAVEN contract for support.All MAVEN data are available on the Planetary Data System(https://pds.nasa.gov).
文摘A mechanism for energy transfer from the solar wind to the Martian ionosphere through open magnetic flux rope is proposed based on the observations by Mars Atmosphere and Volatile EvolutioN(MAVEN).The satellite was located in the dayside magnetosheath at an altitude of about 70o km above the northern hemisphere.Collisions between the hot solar wind protons and the cold heavy ions/neutrals in the subsolar region can cool the protons and heat the heavy ions.As a result,the magnetosheath protons are siphoned into the ionosphere due to the thermal pressure gradient of protons and the heated heavy ions escape along the open magnetic field lines.Although direct collisions in the lower-altitude region were not detected,this physical process is demonstrated by MAVEN measurements of enhanced proton density,decreased proton temperature and oppositely directed motions of hot and cool protons within the flux rope,which are very different from the observational features of the flux transfer events near the Earth's magnetopause.This mechanism could universally exist in many contexts where a collisionless plasma region is connected to a collisional plasma region.By reconstructing the magnetic geometry and the cross-section of the flux rope using the Grad-Shafranov technique,the ion loss rates are quantitatively estimated to be on the order of 1023 s-l,which is much higher than previously estimated.
基金financially supported by the Prospective Joint Research Project of Industry,University and Research in Jiangsu Province(BY2016005-11)National Science and Technology Support Plan(No.2013BAE111B03)。
文摘A spray-drying assisted solid-state method to prepare spherical layer-structured H_(2)TiO_(3) ion sieve(LSTIS)particles is reported herein.The effects of synthesis parameters(calcination temperature,calcination time,and the lithium-titanium molar ratio)on adsorption-desorption performance(the delithiation ratio,titanium dissolution loss,and the adsorption capacity)were investigated.The as-prepared LSTIS exhibited an equilibrium adsorption capacity of 30.08 mg·g^(-1)(average of 25.85 mg·g^(-1) over 5 cycles)and ultra-low titanium dissolution loss of less than 0.12%(average of 0.086%over 5 cycles).The LSTIS showed excellent selectivity toward Li^(+) in Na^(+),K^(+),Mg^(2+),and Ca^(2+) coexisting saline solutions where its adsorption capacity reached 27.45 mg·g^(-1) and the separation factors of Li^(+) over the coexisting cations exceeded 100.The data suggests that the LSTIS is promising to competitively enrich Li^(+) from saline solutions.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFE0301900)the National Natural Science Foundation of China(Grant No.11675083)the Fundamental Research Funds for the Central Universities of China(Grant No.DUT18ZD101).
文摘Nonlinear evolution of multiple toroidal Alfven eigenmodes(TAEs) driven by fast ions is self-consistently investigated by kinetic simulations in toroidal plasmas.To clearly identify the effect of nonlinear coupling on the beam ion loss,simulations over single-n modes are also carried out and compared with those over multiple-n modes,and the wave-particle resonance and particle trajectory of lost ions in phase space are analyzed in detail.It is found that in the multiple-n case,the resonance overlap occurs so that the fast ion loss level is rather higher than the sum loss level that represents the summation of loss over all single-n modes in the single-n case.Moreover,increasing fast ion beta β_h can not only significantly increase the loss level in the multiple-n case but also significantly increase the loss level increment between the single-n and multiple-n cases.For example,the loss level in the multiple-n case for β_h=6.0% can even reach 13% of the beam ions and is 44% higher than the sum loss level calculated from all individual single-n modes in the single-n case.On the other hand,when the closely spaced resonance overlap occurs in the multiple-n case,the release of mode energy is increased so that the widely spaced resonances can also take place.In addition,phase space characterization is obtained in both single-n and multiple-n cases.
基金supported by National Natural Science Foundation of China(No.10905047)
文摘A magnetically insulated transmission line （MITL） is used to transmit high power electric pulses in large pulse power systems. However, current loss is unavoidable, especially when the current density is up to 1 MA/cm. In the paper, the current loss of an MITL made of stainless steel, which is usually used in large pulse power generators, is experimentally studied, and possible mechanisms to explain the current loss of the MITL are analyzed and discussed. From the experimental results, the relationship between loss current density and input current density follows approximately a power law. The loss is also related to the configuration of the MITL.
文摘铜电解液中的As、Sb、Bi离子含量是影响阴极铜质量的重要因素,现有的电解沉积法电耗高、铜损失量大,萃取方法和离子交换法存在液量大的缺陷。本文利用SO_(2)还原As^(5+)和Sb^(5+)、H_(2)O_(2)氧化As3+和Sb3+调整化合价,促使砷锑铋形成沉淀阳极泥的原理,进行了二氧化硫和双氧水并流沉淀方法降低铜电解液中砷锑铋杂质离子的实验研究,结果表明:一定条件下,单独向铜电解液中通入SO_(2)可以降低Sb离子浓度,但As、Bi离子浓度的变化幅度不大;单独向铜电解液中通入H_(2)O_(2)可以降低As、Sb离子浓度,但也会降低Cu、Bi离子浓度,严重时导致阳极钝化;在最佳条件下,H_(2)O_(2)采用滴加方式、加入量为4 m L/L、SO_(2)进气浓度为0.125 g/L、搅拌速度为250 r/min、反应温度为50℃,并流沉淀技术可以实现降低铜电解液中砷锑铋杂质离子的目的,且不会出现阳极钝化现象。
