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The nonlinear three-wave interaction process at the heart of the parametric decay process is studied by launching counter-propagating Alfv\'en waves from antennas placed at either end of the Large Plasma Device (LAPD). A resonance in the…

Plasma Physics · Physics 2013-05-08 S. Dorfman , T. A. Carter

Employing both nonlinear gyrokinetic simulations and theoretical analyses, we have discovered the novel result that, with energetic particle dynamics kept linear, the nonlinear suppression and eventual saturation of reversed-shear Alfv\'en…

Plasma Physics · Physics 2025-12-11 Ruirui Ma , Pengfei Liu , Liu Chen , Fulvio Zonca , Zhiyong Qiu

Nonlinear generation of high frequency mode (HFM) by toroidal Alfven eigenmode (TAE) observed in HL-2A tokamak is analyzed using nonlinear gyrokinetic theory. It is found that, the HFM can be dominated by $|nq-m|=1$ perturbations with…

Plasma Physics · Physics 2019-09-04 Shizhao Wei , Peiwan Shi , Liming Yu , Wei Chen , Ningfei Chen , Zhiyong Qiu

Conditions for net fast ion drive are derived for beam-driven, co-propagating, sub-cyclotron compressional (CAE) and global (GAE) Alfv\'en eigenmodes driven by the Landau resonance with super-Alfv\'enic fast ions. Approximations applicable…

Plasma Physics · Physics 2023-02-10 J. B. Lestz , N. N. Gorelenkov , E. V. Belova , S. X. Tang , N. A. Crocker

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…

Plasma Physics · Physics 2019-06-26 Zhiyong Qiu , Liu Chen , Fulvio Zonca

A workflow is developed based on the ideal MHD model to investigate the linear physics of various Alfv\'en eigenmodes in general axisymmetric toroidal geometry, by solving the coupled shear Alfv\'en wave (SAW) and ion sound wave (ISW)…

Plasma Physics · Physics 2024-04-10 Guangyu Wei , Matteo Valerio Falessi , Tao Wang , Fulvio Zonca , Zhiyong Qiu

Following the analysis on linear spectra of shear Alfv\'en fluctuations excited by energetic particles (EPs) in the Divertor Tokamak Test (DTT) facility plasmas [T. Wang et al., Phys. Plasmas 25, 062509 (2018)], in this work, nonlinear…

Plasma Physics · Physics 2019-01-30 Tao Wang , Xin Wang , Sergio Briguglio , Zhiyong Qiu , Gregorio Vlad , Fulvio Zonca

Generation of zonal ow (ZF) by energetic particle (EP) driven toroidal Alfven eigenmode (TAE) is investigated using nonlinear gyrokinetic theory. It is found that, nonlinear resonant EP contri- bution dominates over the usual Reynolds and…

Plasma Physics · Physics 2016-10-12 Zhiyong Qiu , Liu Chen , Fulvio Zonca

Electron acoustic waves (EAWs) are nonlinear plasma modes characterized by electron trapping, which suppresses the usual Landau damping. Despite being predicted in the 1990s, their excitation and decay mechanisms remain a subject of active…

Plasma Physics · Physics 2025-03-24 F. Valentini , T. M. O'Neil , D. H. Dubin

A recent model coupling the shear-Alfv\'{e}n and acoustic continua, which depends strongly on the equilibrium shaping and on elongation in particular, is employed to explain the properties of Alfv\'{e}nic activity observed on JET plasmas…

Using two-dimensional hybrid-kinetic simulations, we explore the nonlinear "interruption" of standing and traveling shear-Alfv\'en waves in collisionless plasmas. Interruption involves a self-generated pressure anisotropy removing the…

Plasma Physics · Physics 2017-12-14 J. Squire , M. W. Kunz , E. Quataert , A. A. Schekochihin

The magnetic energy of nonlinear Alfven waves in compressible plasmas may be ponderomotively coupled only to ion-acoustic quasi-modes which modulate the wave phase velocity and cause wave-front steepening. In the collisionless plasma with…

Astrophysics · Physics 2009-10-31 M. V. Medvedev

Toroidal Alfven eigenmodes (TAEs) excited in purely ohmically heated plasmas without any auxiliary heating have been identified for the first time in the SUNIST spherical tokamak. The TAE modes are observed during minor disruptions and have…

Plasma Physics · Physics 2016-12-26 Yangqing Liu , Yi Tan , Zhe Gao , Yuhong Xu , Youjun Hu , Song Chai , Yanzheng Jiang , Rui Ke , Heng Zhong , Wenhao Wang

The aim of the present study is to analyze the saturation regime of the Toroidal Alfven Eigenmodes (TAE) in the LHD plasma, particularly the MHD burst. The linear and nonlinear evolution of the TAEs are simulated by the FAR3d code that uses…

Plasma Physics · Physics 2023-04-18 J. Varela , D. A. Spong , Y. Todo , L. Garcia , Y. Ghai , J. Ortiz , R. Seki

Turbulence in tokamaks generates radially sheared zonal flows. Their oscillatory counterparts, geodesic acoustic modes (GAMs), appear due to the action of the magnetic field curvature. The GAMs can be driven unstable by an anisotropic…

Alfven Eigenmodes (AE) can be destabilized by energetic particles in neutral beam injection (NBI) heated plasmas through inverse Landau damping and couplings with gap modes in the shear Alfven continua. We describe the linear evolution of…

Plasma Physics · Physics 2017-10-11 J. Varela , D. Spong , L. Garcia

The rising need for hybrid physical platforms has triggered a renewed interest for the development of agile radio-frequency phononic circuits with complex functionalities. The combination of travelling waves with resonant mechanical…

A Hamiltonian two-field gyrofluid model for kinetic Alfv\'en waves (KAWs) in a magnetized electron-proton plasma, retaining ion finite-Larmor-radius corrections and parallel magnetic field fluctuations, is used to study the inverse cascades…

Plasma Physics · Physics 2021-04-01 George Miloshevich , Dimitri Laveder , Thierry Passot , Pierre-Louis Sulem

This work presents the results of a multi mode ITER study on Toroidal Alfven Eigenmodes, using the nonlinear hybrid HAGIS-LIGKA model. It is found that main conclusions from earlier studies of ASDEX Upgrade discharges can be transferred to…

Plasma Physics · Physics 2017-07-11 Mirjam Schneller , Philipp Lauber , Sergio Briguglio

Neutral-beam-driven, sub-cyclotron compressional (CAE) and global (GAE) \Alfven eigenmodes are routinely excited in spherical tokamaks such as NSTX(-U) and MAST, have been observed on the conventional aspect ratio tokamak DIII-D, and may be…

Plasma Physics · Physics 2021-08-11 J. B. Lestz