Search engine for discovering works of Art, research articles, and books related to Art and Culture
Javascript must be enabled to continue!
Ellipticity induced Alfvén eigenmodes
View through CrossRef
It is shown that noncircularity of tokamak flux surfaces leads to frequency gaps in the magnetohydrodynamic Alfvén continuum. Within these gaps discrete modes having macroscopic structure are shown to exist and have many common features with toroidicity induced Alfvén eigenmodes. The present work focuses on ellipticity. Since κ−1>ε in many tokamaks the ellipticity induced Alfvén eigenmode may indeed be a more robust mode. The most global mode couples the m=1, n=1 and m=3, n=1 ‘‘cylindrical’’ eigenmodes. The region of strong coupling occurs at the q(r)=2 surface and the width of the coupling region is finite and of order (κ−1)a. Furthermore, for typical limiter q(r) profiles satisfying 1≲q≲3, the dominant mode harmonics do not intersect the continuum Alfvén spectrum.
Title: Ellipticity induced Alfvén eigenmodes
Description:
It is shown that noncircularity of tokamak flux surfaces leads to frequency gaps in the magnetohydrodynamic Alfvén continuum.
Within these gaps discrete modes having macroscopic structure are shown to exist and have many common features with toroidicity induced Alfvén eigenmodes.
The present work focuses on ellipticity.
Since κ−1>ε in many tokamaks the ellipticity induced Alfvén eigenmode may indeed be a more robust mode.
The most global mode couples the m=1, n=1 and m=3, n=1 ‘‘cylindrical’’ eigenmodes.
The region of strong coupling occurs at the q(r)=2 surface and the width of the coupling region is finite and of order (κ−1)a.
Furthermore, for typical limiter q(r) profiles satisfying 1≲q≲3, the dominant mode harmonics do not intersect the continuum Alfvén spectrum.
Related Results
On nonlinear evolution of low-frequency Alfvén waves in weakly-expanding solar wind plasmas
On nonlinear evolution of low-frequency Alfvén waves in weakly-expanding solar wind plasmas
A multi-dimensional nonlinear evolution equation for Alfvén waves in weakly-expanding solar wind plasmas is derived by using the reductive perturbation method. The expansion of sol...
Enhanced brain structure-function tethering in transmodal cortex revealed by high-frequency eigenmodes
Enhanced brain structure-function tethering in transmodal cortex revealed by high-frequency eigenmodes
AbstractThe brain’s structural connectome supports signal propagation between neuronal elements, shaping diverse coactivation patterns that can be captured as functional connectivi...
Eigenmodes of fractal drums: A numerical student experiment
Eigenmodes of fractal drums: A numerical student experiment
“Can one hear the shape of a drum?” was a question posed (and made famous) by mathematician Mark Kac in the mid-1960s. It addresses whether a deeper connection exists between the r...
Reflection of Alfvén waves from boundaries with different conductivities
Reflection of Alfvén waves from boundaries with different conductivities
The reflection of Alfvén waves from the ionosphere plays a crucial role because the reflected wave can reduce or enhance the electric field pattern of the incident wave. The ionosp...
The nonsequential double ionization of argon atoms with elliptically polarized laser pulse
The nonsequential double ionization of argon atoms with elliptically polarized laser pulse
With elliptically polarized laser pulse, the nonsequential double ionization (NSDI) of argon atoms is investigated using fully classical ensemble. The results show that the yield o...
Enhanced brain structure-function tethering in transmodal cortex revealed by high-frequency eigenmodes
Enhanced brain structure-function tethering in transmodal cortex revealed by high-frequency eigenmodes
AbstractWhile the link between brain structure and function remains an ongoing challenge, the prevailing hypothesis is that the structure-function relationship may itself be gradua...
Kinetically modified parametric instabilities of circularly polarized Alfvén waves: Ion kinetic effects
Kinetically modified parametric instabilities of circularly polarized Alfvén waves: Ion kinetic effects
Parametric instabilities of parallel propagating, circularly polarized, finite amplitude Alfvén waves in a uniform background plasma is studied, within a framework of one-dimension...
Learning about coronal heating from solar wind observations
Learning about coronal heating from solar wind observations
Vlasov theory describing the interaction of Alfvén-cyclotron fluctuations and ions in the collisionless solar wind predicts that alpha particles should be strongly scattered perpen...