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Nonlinear dynamics of the reversed shear Alfvén eigenmode in burning plasmas
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作者 王涛 魏士朝 +3 位作者 Sergio BRIGUGLIO Gregorio VLAD Fulvio ZONCA 仇志勇 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第5期1-16,共16页
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 revers... 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. 展开更多
关键词 reversed shear Alfvén eigenmode energetic particle nonlinear gyrokinetic theory saturation burning plasma
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Unexpanded nonlinear electromagnetic gyrokinetic equations for magnetized plasmas
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作者 Liu CHEN Fulvio ZONCA Haotian CHEN 《Plasma Science and Technology》 SCIE EI CAS CSCD 2020年第10期1-4,共4页
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 un... 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. 展开更多
关键词 gyrokinetic theory plasma turbulence nonlinear phenomena
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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
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作者 Claudio Di Troia 《Journal of Modern Physics》 2018年第4期701-752,共52页
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 a... 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 Schr&ouml;dinger equation. 展开更多
关键词 Guiding Center Transformation Gyrocenter Transformation KALUZA-KLEIN General Relativity Higher Dimensions Stochastic Quantum Mechanics Schrodinger Equation Lorentz’s Force Law
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Kinetic theory of geodesic acoustic modes in toroidal plasmas:a brief review
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作者 Zhiyong QIU Liu CHEN Fulvio ZONCA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2018年第9期24-49,共26页
Geodesic acoustic modes(GAM) are oscillating zonal structures unique to toroidal plasmas,and have been extensively studied in the past decades due to their potential capabilities of regulating microscopic turbulence... Geodesic acoustic modes(GAM) are oscillating zonal structures unique to toroidal plasmas,and have been extensively studied in the past decades due to their potential capabilities of regulating microscopic turbulences and associated anomalous transport.This article reviews linear and nonlinear theories of GAM;with emphases on kinetic treatment,system nonuniformity and realistic magnetic geometry,in order to reflect the realistic experimental conditions.Specifically,in the linear physics,the resonant wave-particle interactions are discussed,with the application to resonant excitation by energetic particles(EPs).The theory of EP-induced GAM(EGAM) is applied to realistic devices for the interpretation of experimental observations,and global effects due to coupling to GAM continuum are also discussed.Meanwhile,in the nonlinear physics,the spontaneous GAM excitation by microscale turbulences is reviewed,including the effects of various system nonuniformities.A unified theoretical framework of GAM/EGAM is then constructed based on our present understandings.The first-principle-based GAM/EGAM theories reviewed here,thus,provide the tools needed for the understanding and interpretation of experimental/numerical results. 展开更多
关键词 geodesic acoustic mode kinetic theory nonlinear physics energetic particle physics
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Time-of-flight methodologies with large-area diamond detectors for ion characterization in laser-driven experiments 被引量:1
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作者 M.Salvadori G.Di Giorgio +14 位作者 M.Cipriani M.Sciscio C.Verona P.L.Andreoli G.Cristofari R.De Angelis M.Pillon N.E.Andreev P.Antici N.G.Borisenko D.Giulietti M.Migliorati O.Rosmej S.Zahter F.Consoli 《High Power Laser Science and Engineering》 SCIE CAS CSCD 2022年第1期53-63,共11页
The time-of-flight technique coupled with semiconductor detectors is a powerful instrument to provide real-time characterization of ions accelerated because of laser-matter interactions.Nevertheless,the presence of st... The time-of-flight technique coupled with semiconductor detectors is a powerful instrument to provide real-time characterization of ions accelerated because of laser-matter interactions.Nevertheless,the presence of strong electromagnetic pulses(EMPs)generated during the interactions can severely hinder its employment.For this reason,the diagnostic system must be designed to have high EMP shielding.Here we present a new advanced prototype of detector,developed at ENEA-Centro Ricerche Frascati(Italy),with a large-area(15 mm×15 mm)polycrystalline diamond sensor having 150 μm thickness.The tailored detector design and testing ensure high sensitivity and,thanks to the fast temporal response,high-energy resolution of the reconstructed ion spectrum.The detector was offline calibrated and then successfully tested during an experimental campaign carried out at the PHELIX laser facility(E_(L)~100 J,τ_(L)=750 fs,I_(L)(1-2.5)×10^(19)W/cm^(2))at GSI(Germany).The high rejection to EMP fields was demonstrated and suitable calibrated spectra of the accelerated protons were obtained. 展开更多
关键词 diamond detector ion diagnostics laser-matter interaction time of flight
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