首页|Nonlinear dynamics of the reversed shear Alfvén eigenmode in burning plasmas

Nonlinear dynamics of the reversed shear Alfvén eigenmode in burning plasmas

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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,andillustrate 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.

reversed shear Alfvén eigenmodeenergetic particlenonlinear gyrokinetic theorysaturationburning plasma

王涛、魏士朝、Sergio BRIGUGLIO、Gregorio VLAD、Fulvio ZONCA、仇志勇

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Institute for Fusion Theory and Simulation and School of Physics,Zhejiang University,Hangzhou 310027,People's Republic of China

Center for Nonlinear Plasma Science,ENEA C.R.Frascati,Frascati 00044,Italy

National Institute for Fusion Science,Toki,Gifu 509-5292,Japan

Fusion and Nuclear Safety Department,ENEA C.R.Frascati,Frascati 00044,Italy

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国家自然科学基金国家自然科学基金国家自然科学基金Italian Ministry for Foreign Affairs and International Cooperation Project国家重点研发计划国家重点研发计划Users of Excellence program of Hefei Science Center CASEuropean Union via the Euratom Research and Training Programme

122052511227523612261131622CN23GR022019YFE030200032017YFE03019002021HSC-UE016101052200-EUROfusion

2024

10.1088/2058-6272/ad15e0

等离子体科学和技术(英文版)
中国科学院合肥物质科学研究所 中国力学学会

等离子体科学和技术(英文版)

EI
影响因子：0.297
ISSN：1009-0630
年,卷(期)：2024.26(5)
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