检索结果-南通市图书馆

高能量粒子测地声模与Dimits区漂移波相互作用

在线全文

学校读者我要写书评

暂无评论

物理学报 2022年第1期71卷 155-165页

作者：魏广宇陈凝飞仇志勇浙江大学物理学系聚变理论与模拟中心杭州310027 Center for Nonlinear Plasma Science and ENEA C.R.Frascati FrascatiItaly

基于包含驱动和阻尼的三波非线性相互作用模型,构建了一个描述高能量粒子测地声模(EGAM)与Dimits区漂移波湍流相互作用的系统,并在系统的线性增长及非线性振荡阶段分别进行了解析和数值研究.更进一步的数值结果表明,在忽略EGAM的贡献时... 详细信息

基于包含驱动和阻尼的三波非线性相互作用模型,构建了一个描述高能量粒子测地声模(EGAM)与Dimits区漂移波湍流相互作用的系统,并在系统的线性增长及非线性振荡阶段分别进行了解析和数值研究.更进一步的数值结果表明,在忽略EGAM的贡献时,该系统具有随着线性驱动/阻尼率等参数的变化,从极限环振荡经历倍周期分岔最终进入混沌的行为特征.在此基础上,形式上构建了本系统的非线性饱和Dimits区,并研究了EGAM对Dimits区漂移波的影响.结果表明,对于不同幅度和频率的EGAM,被调制后的漂移波将表现出受到激发或抑制的效果.对此,采用相空间分析的方法给出了相应的解释.

关键词：漂移波带状流高能量粒子测地声模三波非线性耦合

nonlinear excitation of a geodesic acoustic mode by reversed shear Alfvén eignemodes

在线全文

学校读者我要写书评

暂无评论

plasma science and Technology 2022年第2期24卷 57-61页

作者：王亚辉王涛魏士朝仇志勇 Institute for Fusion Theory and Simulation and Department of Physics Zhejiang UniversityHangzhou 310027People's Republic of China Center for Nonlinear Plasma Science and ENEA C.R.Frascati Frascati 65-00044Italy

The parametric decay process of a reversed shear Alfvén eigenmeode(rSAE)into a geodesic acoustic mode and a kinetic rSAE is investigated using nonlinear gyrokinetic theory.The excitation conditions mainly require the pump rSAE amplitude to exceed a certain threshold,which could be readily satisfied in burning plasmas operated in steady-state advanced scenario.This decay process can contribute to thermal plasma heating and confinement improvement.

关键词： reversed shear Alfvén eigenmode geodesic acoustic mode gyrokinetic theory nonlinear mode coupling burning plasmas alpha channelling

nonlinear dynamics of the reversed shear Alfvén eigenmode in burning plasmas

在线全文

学校读者我要写书评

暂无评论

plasma science and Technology 2024年第5期 6-21页

作者：王涛魏士朝 Sergio BrIGUGLIO Gregorio VLAD Fulvio ZONcA 仇志勇 Institute for Fusion Theory and Simulation and School of Physics Zhejiang University center for nonlinear plasma science ENEA C.R.Frascati 3. Fusion and Nuclear Safety DepartmentENEA C.R.Frascati

In a tokamak fusion reactor operated at steady state, the equilibrium magnetic field is likely to have reversed shear in the core region, as the noninductive bootstrap current profile generally peaks off-axis. The reversed shear Alfvén eigenmode(rSAE) as a unique branch of the shear Alfvén wave in this equilibrium, can exist with a broad spectrum in wavenumber and frequency,and be resonantly driven unstable by energetic particles(EP). After briefly discussing the rSAE linear properties in burning plasma condition, we review several key topics of the nonlinear dynamics for the rSAE through both wave-EP resonance and wave-wave coupling channels,and illustrate their potentially important role in reactor-scale fusion plasmas. By means of simplified hybrid MHD-kinetic simulations, the rSAEs are shown to have typically broad phase space resonance structure with both circulating and trapped EP, as results of weak/vanishing magnetic shear and relatively low frequency. Through the route of wave-EP nonlinearity, the dominant saturation mechanism is mainly due to the transported resonant EP radially decoupling with the localized rSAE mode structure, and the resultant EP transport generally has a convective feature. The saturated rSAEs also undergo various nonlinear couplings with other collective oscillations. Two typical routes as parametric decay and modulational instability are studied using nonlinear gyrokinetic theory, and applied to the scenario of spontaneous excitation by a finite amplitude pump rSAE. Multiple rSAEs could naturally couple and induce the spectral energy cascade into a low frequency Alfvénic mode, which may effectively transfer the EP energy to fuel ions via collisionless Landau damping. Moreover, zero frequency zonal field structure could be spontaneously excited by modulation of the pump rSAE envelope, and may also lead to saturation of the pump rSAE by both scattering into stable domain and local distortion of the continuum structure.

关键词：

A Gyrokinetic simulation model for low frequency electromagnetic fluctuations in magnetized plasmas

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2021年第4期64卷 90-95页

作者： Liu chen HaoTian chen Fulvio Zonca Yu Lin Institute for Fusion Theory and Simulation and Department of Physics Zhejiang UniversityHangzhou 310027China Department of Physics and Astronomy University of CaliforniaIrvineCalifornia 92697USA Institute of Space science and Technology Nanchang UniversityNanchang 330031China center for nonlinear plasma science and c.r.enea frascati-c.P.65 Frascati 00044Italy Physics Department Auburn UniversityAuburn AL 36849USA

We present a new model for simulating the electromagnetic fluctuations with frequencies much lower than the ion cyclotron frequency in plasmas confined in general magnetic configurations.This novel model(termed as GK-E&B)employs nonlinear gyrokinetic equations formulated in terms of electromagnetic fields along with momentum balance equations for solving fields.It,thus,not only includes kinetic effects,such as wave-particle interaction and microscopic(ion Larmor radius scale)physics;but also is computationally more efficient than the conventional formulation described in terms of potentials.As a benchmark,we perform linear as well as nonlinear simulations of the kinetic Alfvén wave;demonstrating physics in agreement with the analytical theories.

关键词： plasma kinetic equations Gyrokinetics Gyrokinetic simulations particle orbit and trajectory

Oxidation in ca/K-1144 iron-based superconductors polycrystalline compounds

在线全文

学校读者我要写书评

暂无评论

Superconductivity 2023年第4期8卷 9-17页

作者： Zuhawn Sung Anastasiya Duchenko Giuseppe celentano Jaeyel Lee Xiaobing Hu Nicola Pompeo Francesca Varsano Andrea Masi Fermi National Accelerator Laboratory BataviaIL 60510USA Universitàdegli Studi roma Tre Dipartimento di Ingegneria IndustrialeElettronica e MeccanicaVia Vito Volterra 6200146 RomaItaly enea C.R.FrascatiVia Enrico Fermi 4500044 FrascatiItaly Department of Materials science and Engineering Northwestern UniversityEvanstonIL 60208USA The NUANcE center Northwestern UniversityIL 60208USA enea C.R.CasacciaVia Anguillarese 30100123 RomaItaly

Iron‐based superconductors(IBScs)are a class of material under investigation for the development of superconducting wires in the low‐temperature‐high magnetic fields power application.Among the various families of IBScs,the 1144 caKFe_(4)As_(4) compound is a promising material able to achieve outstanding superconducting properties with a cheap and simple chemical composition.Oxidation,in these compounds,is considered an obstacle for high intergranular critical current density,J_(c,GB).A study devoted to the evaluation of oxidation phenomena and their effects on the superconducting properties is thus needed in order to fully understand the involved mechanisms.From the evaluation of polycrystalline samples obtained by a mechanochemically assisted synthesis route,a degradation of the critical temperature and critical currents has been observed concurrently with oxygen accumulation at grain boundaries in open porosities.However,the crystalline structure at an atomic level seems not affected,as well as intragranular superconducting properties assessed by means of calorimetric methods.These results suggest that loss of superconducting properties in ca/K‐1144 compounds following oxidation is significantly associated with the worsening of grain connectivity.

关键词： Grain boundaries Superconductivity Oxidation Microstructure Iron based superconductors

Non-Perturbative Guiding center and Stochastic Gyrocenter Transformations:Gyro-Phase Is the Kaluza-Klein 5^(th) Dimension also for reconciling General relativity with Quantum Mechanics

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Physics 2018年第4期9卷 701-752页

作者： claudio Di Troia enea Fusion and Nuclear Safety DepartmentC.R.FrascatiItaly

The non perturbative guiding center transformation is extended to the relativistic regime and takes into account electromagnetic fluctuations. The main solutions are obtained in covariant form: the gyrating particle and the guiding particle solutions, both in gyro-kinetic as in MHD orderings. Moreover, the presence of a gravitational field is also considered. The way to introduce the gravitational field is original and based on the Einstein conjecture on the feasibility to extend the general relativity theory to include electromagnetism by geometry, if applied to the extended phase space. In gyro-kinetic theory, some interesting novelties appear in a natural way, such as the exactness of the conservation of a magnetic moment, or the fact that the gyro-phase is treated as the non observable fifth dimension of the Kaluza-Klein model. Electrodynamics becomes non local, without the inconsistency of self-energy. Finally, the gyrocenter transformation is considered in the presence of stochastic e.m. fluctuations for explaining quantum behaviors via Nelson’s approach. The gyrocenter law of motion is the Schrödinger equation.

关键词： Guiding center Transformation Gyrocenter Transformation Kaluza-Klein General relativity Higher Dimensions Stochastic Quantum Mechanics Schrodinger Equation Lorentz’s Force Law

Self-consistent kinetic theory with nonlinear wave-particle resonances

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

plasma science and Technology 2019年第12期21卷 6-12页

作者： Liu cHEN Fulvio ZONcA Institute for Fusion Theory and Simulation and Department of Physics Zhejiang UniversityHangzhou 310027People's Republic of China Department of Physics and Astronomy University of CaliforniaIrvineCA 92697-4575United States of America enea C.R.FrascatiVia E.Fermi 45I-00044 Frascati(Rome)Italy

We have developed, based on the oscillating-center transformation, a general theoretical approach for self-consistent plasma dynamics including, explicitly, effects of nonlinear(higherorder) wave-particle resonances. A specific example is then given for low-frequency responses of trapped particles in axisymmetric tokamaks. Possible applications to transport as well as nonlinear wave growth/damping are also briefly discussed.

关键词： gyrokinetics nonlinear phenomena:waves wave propagation and other interactions(including parametric effects,mode coupling,ponderomotive) fusion products effects(e.g.alpha-particles,etc) fast particle effects particle orbit and trajectory perturbative methods

Unexpanded nonlinear electromagnetic gyrokinetic equations for magnetized plasmas

在线全文

学校读者我要写书评

暂无评论

plasma science and Technology 2020年第10期22卷 1-4页

作者：陈骝 Fulvio ZONcA 陈昊天 Institute for Fusion Theory and Simulation and Department of Physics Zhejiang UniversityHangzhou 310027People’s Republic of China Department of Physics and Astronomy University of CaliforniaIrvineCA 92697United States of America enea Fusion and Nuclear Safety DepartmentC.R.FrascatiVia E.Fermi 4500044 Frascati(Roma)Italy Institute of Space science and Technology Nanchang UniversityNanchang 330031.People's Republic of China

nonlinear electromagnetic gyrokinetic equations have been constructed without expanding the field variables into background and finite but small-amplitude fluctuating components. At the long-wavelength limit, these unexpanded nonlinear gyrokinetic equations recover the wellknown drift-kinetic equations. At the expanded limit, they recover the usual nonlinear gyrokinetic equations. These equations can therefore be applied to long-term simulations covering from microscopic to macroscopic spatial scales.

关键词： gyrokinetic theory plasma turbulence nonlinear phenomena

Theoretical and numerical studies of chorus waves: A review

在线全文

学校读者我要写书评

暂无评论

science china Earth sciences 2020年第1期63卷 78-92页

作者： Xin TAO Fulvio ZONcA Liu cHEN Yifan WU cAS Key Laboratory of Geospace Environment Department of Geophysics and Planetary SciencesUniversity of Science and Technology of ChinaHefei 230026China cAS center for Excellence in comparative Planetology Hefei 230026China enea centro ricerche frascati CP 65-00044 FrascatiItaly Institute of Fusion Theory and Simulation and Department of Physics Zhejiang UniversityHangzhou 310027China Department of Physics and Astronomy University of CaliforniaIrvineCA 92697USA

Theoretical and numerical models of chorus waves are reviewed in this paper. Specifically, we focus on the nonlinear wave particle interactions and the current understanding of the frequency chirping of rising tone chorus waves. Various other related topics, such as the optimal excitation condition of chorus, the formation of subpackets, and the non-adiabaticity of the nonlinear interaction are also discussed. We end this review paper with a short list of questions of chorus waves that are still under research and debate.

关键词： chorus waves Frequency chirping Triggered emissions