Related papers: Low-frequency shear Alfv\'en waves at DIII-D: theo…
The resonant and non-resonant effects of core plasma on the excitation of low frequency modes with $\omega < \omega_{BAE}$, such as Beta-induced Alfv\'en Acoustic Eigenmodes (BAAEs) and Kinetic Ballooning Modes (KBMs) are examined in the…
Complete asymptotic expansions are developed for slow, Alfv\'en and fast magnetohydrodynamic waves at the base of an isothermal three-dimensional (3D) plane stratified atmosphere. Together with existing convergent Frobenius series solutions…
Alfven Eigenmodes are destabilized at the DIII-D pedestal during transient beta drops in high poloidal beta discharges with internal transport barriers (ITBs), driven by n=1 external kink modes, leading to energetic particle losses. There…
An experimental investigation of nonlinear interactions between shear Alfv\'{e}n waves in a laboratory plasma is presented. Two Alfv\'{e}n waves, generated by a resonant cavity, are observed to beat together, driving a low frequency…
Analytical expressions for the dispersion relations and polarizations of low-frequency waves in magnetized plasmas based on two-fluid model are obtained. The properties of waves propagating at different angles (to the ambient magnetic field…
We present a gyrokinetic theory for the electromagnetic waves and instabilities with frequencies much lower than the ion cyclotron frequency in finite-$\beta$ anisotropic uniform plasmas. Here, $\beta$ is the ratio between plasma and…
A part analytical, part numerical ideal MHD analysis of low-frequency Alfven wave physics in the H-1 stellarator is given. The three-dimensional, compressible ideal spectrum for H-1 is presented and it is found that despite the low beta…
Alfven Eigenmodes and magneto-hydrodynamic modes are destabilized in DIII-D reverse magnetic shear configurations and may limit the performance of the device. We use the reduced MHD equations in a full 3D system, coupled with equations of…
Reduced fluid models including electron inertia and ion finite Larmor radius corrections are derived asymptotically, both from fluid basic equations and from a gyrofluid model. They apply to collisionless plasmas with small ion-to-electron…
In many discharges at ASDEX Upgrade fast particle losses can be observed due to Alfv\'enic gap modes, Reversed Shear Alfv\'en Eigenmodes or core-localized Beta Alfv\'en Eigenmodes. For the first time, simulations of experimental conditions…
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…
In this paper, we study the weakly-compressive high-frequency plasma waves which are superposed on a large-amplitude Alfv\'en wave in a multi-fluid plasma consisting of protons, electrons, and alpha particles. For these waves, the plasma…
In the approximation of linear dissipative magnetohydrodynamics (MHD) it can be shown that driven MHD waves in magnetic plasmas with high Reynolds number exhibit a near resonant behaviour if the frequency of the wave becomes equal to the…
Evolution of the parametric decay instability (PDI) of a circularly polarized Aflv\'en wave in a turbulent low-beta plasma background is investigated using 3D hybrid simulations. It is shown that the turbulence reduces the growth rate of…
Linear properties of kinetic Alfv\'{e}n waves (KAWs) and kinetic slow waves (KSWs) are studied in the framework of two-fluid magnetohydrodynamics. We obtain the wave dispersion relations that are valid in a wide range of the wave frequency…
Using one-dimensional numerical simulations, we study the elementary process of Alfv\'{e}n wave reflection in a uniform medium, including nonlinear effects. In the linear regime, Alfv\'{e}n wave reflection is triggered only by the…
We report on first evidence of wave activity during neutral beam heating in KSTAR plasmas: 40 kHz magnetic fluctuations with a toroidal mode number of n=1. Our analysis suggests this a beta-induced Alfven eigenmode resonant with the q=1…
We describe the interaction of parallel-propagating Alfv\'en waves with ion-acoustic waves and other Alfv\'en waves, in magnetized, high-$\beta$ collisionless plasmas. This is accomplished through a combination of analytical theory and…
Nonlinear excitation of low frequency zonal structure (LFZS) by beta-induced Alfven eigenmode (BAE) is investigated using nonlinear gyrokinetic theory. It is found that electrostatic zonal flow (ZF), rather than zonal current, is…
We study the nonlinear evolution of very oblique small-scale Alfv\'en waves with $k_\perp d_i\gtrsim 1$. At these scales, the waves become significantly compressive, unlike in MHD, due to the Hall term in the equations. We demonstrate that…