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Landau damping of electrons with bouncing motion in a radio-frequency plasma

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Chinese Physics B 2021年第12期30卷 484-494页

作者： Jun Tao nong xiang Yemin Hu Yueheng Huang Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China Advanced Energy Research Center Shenzhen UniversityShenzhen 518060China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

One-dimensional particle simulations have been conducted to study the interaction between a radio-frequency electrostatic wave and electrons with bouncing *** is shown that bounce resonance heating can occur at the first few harmonics of the bounce frequency(nω_(b),n=1,2,3,...).In the parameter regimes in which bounce resonance overlaps with Landau resonance,the higher harmonic bounce resonance may accelerate electrons at the velocity much lower than the wave phase velocity to Landau resonance region,enhancing Landau damping of the ***,Landau resonance can increase the number of electrons in the lower harmonic bounce resonance *** electrons can be efficiently *** result might be applicable for collisionless electron heating in low-temperature plasma discharges.

关键词： first few harmonics bounce resonance Landau resonance resonance overlaps

Effects of fast ions produced by ICRF heating on the pressure at EAST

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Plasma Science and Technology 2020年第2期22卷 38-46页

作者： Zhen ZHENG nong xiang Cheng YANG Yingfeng XU Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China Center for Magnetic Fusion Theory Chinese Academy of SciencesHefei 230031People's Republic of China

Ion cyclotron resonance heating(ICRH),which can produce fast ions,is an important auxiliary heating method at *** analyze the effect of ICRH-induced fast ions on the plasma pressure at EAST,simulations are performed using TRANSP and TORIC *** is found that the ICRF-induced fast ion pressure cannot be negligible when the ICRF power is sufficiently *** magnitude of the total ion pressure can be raised up to 60%of the total pressure as the input power rises above 3 *** pressure profile is also significantly modified when the resonant layer is *** 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.

关键词： ICRH equilibrium fast ion pressure minority heating

Geometric field theory and weak Euler-Lagrange equation for classical relativistic particle-field systems

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Frontiers of physics 2018年第4期13卷 209-220页

作者： Peifeng Fan Hong Qin Jian Liu nong xiang Zhi Yu Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 China Science Island Branch of Graduate School University of Science and Technology of China Hefei 230031 China Department of Modern Physics University of Science and Technology of China Hefei 230026 China Center for Magnetic Fusion Theory Chinese Academy of Sciences Hefei 230031 China Plasma Physics Laboratory Princeton University Princeton NJ 08543 USA

A manifestly covariant, or geometric, field theory of relativistic classical particle-field systems is devel- oped. The connection between the space-time symmetry and energy-momentum conservation laws of the system is established geometrically without splitting the space and time coordinates; i.e., space- time is treated as one entity without choosing a coordinate system. To achieve this goal, we need to overcome two difficulties. The first difficulty arises from the fact that the particles and the field reside on different manifolds. As a result, the geometric Lagrangian density of the system is a function of the 4-potential of the electromagnetic fields and also a functional of the particles＇ world lines. The other difficulty associated with the geometric setting results from the mass-shell constraint. The standard Euler-Lagrange （EL） equation for a particle is generalized into the geometric EL equation when the mass-shell constraint is imposed. For the particle-field system, the geometric EL equation is further generalized into a weak geometric EL equation for particles. With the EL equation for the field and the geometric weak EL equation for particles, the symmetries and conservation laws can be established geometrically. A geometric expression for the particle energy-momentum tensor is derived for the first time, which recovers the non-geometric form in the literature for a chosen coordinate system.

关键词： relativistic particle-field system different manifolds mass-shell constraint geometric weakEuler-Lagrange equation symmetry conservation laws

Calorimetric Studies on Enthalpy Relaxation in Maltitol Glass Transition Based on Phenomenological Models

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Chemical Research in Chinese Universities 2012年第6期28卷 1078-1085页

作者： YE Bin GAO Cai YANG Suo LIU xiang-nong JIANG Bin School of Mechanical and Automotive Engineering Hefei University of Technology Hefei 230009 P. R. China

To investigate the enthalpy relaxation behavior of maltitol glass system,differential scanning calorimetry（DSC） was used to obtain the specific heat capacity[C p（T）] near the glass transition temperature（T g） at different cooling rates ranged between 1 and 20 K/*** phenomenological models of enthalpy relaxation,ToolNarayanaswamy-Moynihan（TNM） model,Adam-Gibbs-Vogel（AGV） model and Gómez Ribelles（GR） model,were used to simulate the experimental *** models＇ parameters were obtained via a curve-fitting *** results indicate that TNM and AGV models gave the almost identical prediction powers and can reproduce the curves of experimental C p（T） very ***,the prediction power of GR model evolved from configurational entropy approach is not so good as those of TNM and AGV *** particular,the metastable limit state parameter（δ） introduced by Gómez Ribelles has insignificant effect on the enthalpy relaxation of the small molecular hydrogen-bonding glass system.

关键词： Differential scanning calorimetry(DSC) Maltitol Glass transition Enthalpy relaxation Tool-Narayanaswamy-Moynihan(TNM) model Adam-Gibbs-Vogel(AGV) model Gómez Ribelles(GR) model Dynamic fragility

Relativistic effect on synergy of electron cyclotron and lower hybrid waves on EAST

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Plasma Science and Technology 2021年第12期23卷 32-41页

作者： Longhao MA nong xiang Yueheng HUANG Yemin HU Xuemei ZHAI Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China Advanced Energy Research Center Shenzhen UniversityShenzhen 518060People's Republic of China Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic EngineeringShenzhen UniversityShenzhen 518060People's Republic of China

In recent experiments on EAST,the electron temperature at the center can be raised to 9.7 ke V by injecting electron cyclotron(EC)and lower hybrid(LH)waves *** such strong core electron heating,the relativistic effect could play an important role in the interactions between the plasma and *** order to explore the relativistic effect on synergy between the EC and LH waves on EAST,ray-tracing/Fokker-Planck simulations are conducted to investigate electron heating for a typical discharge with a center electron temperature of 9.7 ke *** is found that the relativistic effect can cause the EC wave to deposit its power deeper in the plasma core,where the synergy between the EC and LH waves occurs and enhances the absorption of the LH *** a result,a high center electron temperature can be achieved.

关键词： electron cyclotron waves lower hybrid waves synergy effect relativistic effect

Parametric decay instabilities of lower hybrid waves on CFETR

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Chinese Physics B 2022年第9期31卷 386-396页

作者： Taotao Zhou nong xiang Chunyun Gan Guozhang Jia Jiale Chen Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China Centre of Magnetic Fusion Theory Chinese Academy of SciencesHefei 230031China

The lower hybrid current drive is a potential candidate for sustaining plasma current in tokamak steady-state oper-ations,which could be used in China Fusion Engineering Test Reactor(CFETR)with input power up to a few tens of *** high input power could trigger the well-known parametric instabilities(PIs)at the plasma edge affect-ing the propagation and absorption of the lower hybrid pump *** analytically solving the nonlinear dispersion relation describing PIs,an explicit expression of the PI growth rate is obtained and analyzed in *** is found that pressure is the key parameter determining the PI *** sound quasi-mode is the dominant decay channel in the low-pressure regime,while the ion cyclotron quasi-mode(ICQM),as well as its harmonics,becomes dominant in the intermediate *** the high-pressure regime,only one mixed channel is found,which is related to Landau damping by free-streaming *** expressions of growth rates of these decay channels are also obtained to show the parameter dependence at different pressure *** above analytical results are used to estimate the PIs on a typical profile of CFETR,and verified by corresponding numerical *** is found to be the strongest decay channel with a considerable growth rate for CFETR.

关键词： lower hybrid parametric instability CFETR

Estimation of tungsten production from the upper divertor in EAST during edge localized modes

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Chinese Physics B 2019年第12期28卷 223-230页

作者： Jing Ou nong xiang Zong-Zheng Men Ling Zhang Ji-Chan Xu Wei Gao Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China Magnetic Fusion Theory Chinese Academy of SciencesHefei 230031China

During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of e V in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium(D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon(C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.

关键词： sheath edge localized modes impact energy

Numerical study on the loss of fast ions produced by minority ion cyclotron resonance heating in EAST

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Plasma Science and Technology 2021年第11期23卷 1-8页

作者： Dingzong ZHANG Youjun HU nong xiang Cheng YANG Wei SHEN Yanqing HUANG Hongbo LIU College of Physics and Electronic Engineering.Hengyang Normal University Hengyang 421008People's Republic of China Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People's Republic of China

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 *** dominant fast loss comes from trapped ions,rather than from passing *** the location of resonance layer at the plasma core may be more beneficial to the EAST tokamak *** addition,the loss distribution of fast ions is *** results show that the fast ions are mainly lost near the midplane in the poloidal direction,but almost uniformly in the toroidal ***,we investigate the dependence of fast ion loss on the ICRH *** 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.

关键词： ion cyclotron resonance heating the loss of fast ions EAST

Effect of kinetic ions on the toroidal double-tearing modes

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Chinese Physics B 2023年第2期32卷 366-371页

作者：张睿博叶磊 Yang Chen 项农杨小庆 Hefei Institutes of Physical Science Chinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China Center for Integrated Plasma Studies University of Colorado at BoulderBoulderColorado 80309USA

We investigate the effects of kinetic ions on double-tearing modes(DTMs) using the gyrokinetic particle-in-cell simulation code GEM with a gyrokinetic ion/fluid electron hybrid model. It is found that the ion kinetic effects can decrease the growth rate of the DTMs. This effect is more significant for stronger coupling of DTMs with smaller distance between the rational surfaces. Kinetic ions can also enhance the coupling effect between the two rational surfaces. Energy transfer analyses between particles and wave fields show that the stabilizing effect of kinetic ions comes mainly from the perpendicular magnetic drift of ions in the coupling region and around the outer rational surface.

关键词： double-tearing modes kinetic ions coupling effect