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Alfvén Instabilities Excited by energetic particles in a Parameter Regime Similar to EAST Operation

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Plasma Science and Technology 2013年第8期15卷 750-754页

作者：王军胡纯栋胡双辉吴斌丁斯晔 Institute of Plasma Physics Chinese Academy of Sciences College of Science Guizhou University

The kinetic excitation of ideal magnetohydrodynamic （MHD） Alfvén instabilities is investigated for operations at the EAST tokamak. The instabilities include α-induced toroidal Alfvén eigenmodes （αTAE; here, α =-q2 Rdβ/dr, with q being the safety factor, β the ratio between the plasma and magnetic pressures, R the major radius, and r the minor radius）, toroidicity-induced Alfvén eigenmodes （TAE）, and the energetic particle continuum mode （EPM）. The αTAE, trapped by α-induced potential wells along the magnetic field line, can be readily destabilized by energetic particles due to negligible continuum damping via wave energy tunneling. It is shown for the geometry and the parameters similar to those of the EAST equilibrium that αTAE is different not only from the EPM by the potential-well determined frequency, but also from the TAE by the broad frequency spectrum outside the toroidal frequency gap.

关键词： energetic particles Alfvén wave MHD instability

Kinetic Theories of Geodesic Acoustic Modes：Radial Structure,Linear Excitation by energetic particles and Nonlinear Saturation＇

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Plasma Science and Technology 2011年第3期13卷 257-266页

作者： QIU Zhiyong(仇志勇) Fulvio ZONCA CHEN Liu(陈骝) Institute for Fusion Theory and Simulation Zhejiang UniversityHangzhou 310027China Associazione Euratom=ENEA sulla Fusione C. P. 65 -I-00044-Frascati. Italy Dept. of Physics and Astronomy Univ. of California Irvine CA 92697-4575 USA

Geodesic acoustic modes（GAMs）are oscillating zonal mode structures unique to toroidal plasmas and are capable of regulating microscopic turbulence and associated ***,three important aspects of GAM dynamics are investigated,namely（1） GAM continuous spectrum and its mode conversion to kinetic GAM （KGAM）;（2） 1inear excitation of energetic particle induced GAM （EGAM） and its coupling to the GAM continuum, and （3） nonlinear ***

关键词： geodesic acoustic mode continuum energetic particles wave particle trapping

Analysis of the energetic particles Around the Chili Earthquake of M8.8

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Earthquake Research in China 2011年第2期25卷 166-172页

作者： Huang Jianping Liu Jing Ouyang Xinyan Li Wenjing Institute of Earthquake Science CEA Beijing 100036China Tangshan Deformation Observation Station of the First Crust Monitoring Center CEA Tangshan 063001 China

Based on the IDP data from the French DEMETER satellite,global distribution is shown,which corresponds to three precipitation zones:the aural precipitation zone,the mid-high latitude precipitation zone and the South Atlantic precipitation *** the Chili earthquake with M8.8 which occurred on February 27,2010 is taken as an *** IDP fluxes from repeat orbits are compared and the results show that there is a clear enhancement on February 26,2010,just one day ahead of the Chili *** the south zone with L=2.1～2.7,the flux on February 26 is higher than that on previous *** in the north zone with L=2.1～2.7,there is no clear change during the day but great enhancement during the night,which is close to the time of the *** the same time,the flux on February 26 near the equator is far lower than that on previous days.

关键词： Chili earthquake DEMETER IDP flux energetic particles Repeat orbits

Equatorial aurora: the aurora-like airglow in the negative magnetic anomaly

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National Science Review 2020年第10期7卷 1606-1615页

作者： Fei He Yong Wei Weixing Wan Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences

The most fantastic optical phenomena in the Earth’s upper atmosphere are the auroras. They are highly informative indicators of solar activity, geomagnetic activity, upper atmospheric structures and dynamics,and magnetospheric energetic particles. An area where the geomagnetic field differs significantly from the expected symmetric dipole, such as at the South Atlantic Anomaly, where the magnetic field intensity is low,gives rise to stronger precipitation of energetic particles into the upper atmosphere. Impact excitation and the subsequent airglow emissions exhibit aurora-like dynamic signatures. Nomenclatures of nonpolar aurora or equatorial auroras are similar to those used with the polar auroras owing to their similar excitation mechanisms. This paper provides an overview of the knowledge and the challenges concerning auroral activity at the South Atlantic Anomaly, or more generally, at the negative magnetic anomaly. We emphasize systematic investigation of the equatorial auroras to reveal the temporal and spatial evolution of the magnetic anomaly and the behaviour of energetic particles in near-Earth space.

关键词： aurora geomagnetic field South Atlantic Anomaly negative magnetic anomaly energetic particles

The CASTOR-K Code,Recent Developments and Applications

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Plasma Science and Technology 2015年第2期17卷 89-96页

作者： F.NABAIS D.BORBA R.COELHO A.FIGUEIREDO J.FERREIRA N.LOUREIRO P.RODRIGUES Associao EURATOM/IST Instituto de Plasmas e Fuso Nuclear-Instituto Superior TcnicoUniversidade de Lisboa

The CASTOR-K code is a hybrid magnetohydrodynamic （MHD）-drift kinetic code developed for the study of MHD modes in the presence of energetic ion populations. It allows a fast assessment of the linear stability of the modes, as well as an accurate calculation of damping due to thermal species （Landau damping）. These capabilities make the code an invaluable tool for parametric studies and data analysis. In recent years, CASTOR-K has been mostly used to analyze JET data, including the identification of mechanisms involved in the expulsion of energetic ions from the plasma. However, in order to prepare the code to be used for a wider range of tokamaks including ITER, the code is being subject to a series of important improvements. These improvements aim not only to introduce new physics in the code but also to make it capable of exchanging data with other codes through its integration in modelling infrastructures. In this paper a description of the CASTOR-K code is presented, as well as a summary of the most important results obtained with this code and a description of the new improvements being implemented.

关键词： controlled fusion tokamaks plasma instabilities magnetohydrodynamics(MHD) Alfven waves energetic particles

Discrete Alfvén eigenmodes in the CFETR steady-state scenario

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Chinese Physics B 2023年第5期32卷 544-553页

作者：兰源丹胡双辉欧阳思杰朱万坡黄旋格 College of Physics Guizhou UniversityGuiyang 550025China

The stability features of discrete Alfvén eigenmodes(αTAEs) trapped by α-induced potential wells are explored in the China Fusion Engineering Test Reactor(CFETR) advanced steady-state operation environment, where α denotes a measure of the pressure gradient. For the reversed magnetic shear(RS) H-mode scenario with an enhanced internal transport barrier(ITB), the αTAEs are trapped in the electron cyclotron(EC) power deposition region and the effects of different pedestals on αTAEs are analyzed. For the negative off-axis magnetic shear scenario, the αTAEs are discussed, and the effect of different magnetic shears on the α TAEs is presented. Finally, the effects of beam energies and pitch-angle distributions onαTAE stability are also presented.

关键词： Alfvén wave energetic particles plasma instability

Mode structure symmetry breaking of reversed shear Alfvén eigenmodes and its impact on the generation of parallel velocity asymmetries in energetic particle distribution

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Plasma Science and Technology 2022年第2期24卷 17-27页

作者： Guo MENG Philipp LAUBER Xin WANG Zhixin LU Max-Planck-Institut fiir Plasmaphysik D-85748 GarchingGermany

In this work,the gyrokinetic eigenvalue code LIGKA,the drift-kinetic/MHD hybrid code HMGC and the gyrokinetic full-f code TRIMEG-GKX are employed to study the mode structure details of reversed shear Alfvén eigenmodes(RSAEs).Using the parameters from an ASDEXUpgrade plasma,a benchmark with the three different physical models for RSAE without and with energetic particles(EPs)is carried *** agreement has been found for the mode frequency and the growth *** structure symmetry breaking(MSSB)is observed when EPs are included,due to the EPs’non-perturbative *** is found that the MSSB properties are featured by a finite radial wave phase velocity,and the linear mode structure can be well described by an analytical complex Gaussian expressionФ(s)=e^(-σ(s-s_(0))^(2))with complex parametersσand s_(0),where s is the normalized radial *** mode structure is distorted in opposite manners when the EP drive shifted from one side of qminto the other side,and specifically,a non-zero average radial wave number with opposite signs is *** initial EP density profiles and the corresponding mode structures have been used as the input of HAGIS code to study the EP *** parallel velocity of EPs is generated in opposite directions,due to different values of the average radial wave number,corresponding to different initial EP density profiles with EP drive shifted away from the qmin.

关键词： reversed shear Alfvén eigenmode symmetry breaking energetic particles non-perturbative effects

Effects of q-profiles of a weak magnetic shear on energetic ion excited q=1 mode in tokamak plasmas

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Chinese Physics B 2016年第1期25卷 690-696页

作者：李泽宇王先驱王晓钢 State Key Lab of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China Institute of Fusion Science.School of Physical Science and Technology Southwest Jiaotong UniversityChengdu 610031China Department of Physics Harbin Institute of TechnologyHarbin 150001China

In this paper, we study the effect of safety factor profiles, particularly with a very weak magnetic shear, on the m/n = 1 mode excited by energetic ions in tokamak plasmas. It is found that the profile plays a significant role in the onset of the mode, and the thresholds for the instability are also derived. The numerical results for configurations with conventional or reversed non monotonic magnetic shears are discussed. The effects of radial location of rational surfaces, edge q value, and flatness of q-profile on the energetic ion excited mode are further analyzed in detail.

关键词： safety factor profile magnetohydrodynamics tokamak energetic particles

Highly energetic and flammable metallic glasses

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Science China(Physics,Mechanics & Astronomy) 2020年第7期63卷 68-72页

作者： BangSheng Yu YongHao Sun HaiYang Bai WeiHua Wang Institute of Physics Chinese Academy of SciencesBeijing 100190China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBejing 100049China Songshan Lake Materials Laboratory Dongguan 523808China

energetic materials are solids that release a large amount of energy in combustion. The evaluation depends on both combustion heat and ignition temperature. Conventional non-metallic materials have low ignition temperature but small combustion heat,whereas metals have large combustion heat but high ignition temperatures. We show that many metallic glasses, combining the merits of both metals and non-metals, have large combustion heat, approximately twice that of the non-metals, and low ignition temperature that is several hundreds of Kelvin lower than that of the metals. The ease in igniting metallic glass results from the low thermal conductivity of the materials and the storage of energy in their liquid-like atomic structure. Metallic glass ribbons outweigh metallic nanoparticles due to their high production efficiency, low cost and nontoxicity. The findings suggest that metallic glasses are alternative energetic materials.

关键词： metallic glass energetic particles combustion fast ignition nanoscale materials