English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In ideal MHD, shear Alfv\'{e}n eigenmodes may experience dissipationlessdamping due to resonant interaction with the shear Alfv\'{e}n continuum. Thiscontinuum damping can make a significant contribution to the overallgrowth/decay rate of shear Alfv\'{e}n eigenmodes, with consequent implicationsfor fast ion transport. One method for calculating continuum damping is tosolve the MHD eigenvalue problem over a suitable contour in the complex plane,thereby satisfying the causality condition. Such an approach can be implementedin three-dimensional ideal MHD codes which use the Galerkin method. Analyticfunctions can be fitted to numerical data for equilibrium quantities in orderto determine the value of these quantities along the complex contour. Thisapproach requires less resolution than the established technique of calculatingdamping as resistivity vanishes and is thus more computationally efficient. Thecomplex contour method has been applied to the three-dimensional finite elementideal MHD code CKA . In this paper we discuss the application of the complexcontour technique to calculate the continuum damping of global modes in tokamakas well as torsatron, W7X and H1-NF stellarator cases. To the authors'knowledge these stellarator calculations represent the first calculation ofcontinuum damping for eigenmodes in fully three-dimensional equilibria. Thecontinuum damping of global modes in W7X and H1-NF stellarator configurationsinvestigated is found to depend sensitively on coupling to numerous poloidaland toroidal harmonics.

Calculation of continuum damping of Alfv\'en eigenmodes in 2D and 3D cases