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

Conditions for net fast ion drive are derived for beam-driven,co-propagating, sub-cyclotron compressional (CAE) and global (GAE) Alfv\'eneigenmodes driven by the Landau resonance with super-Alfv\'enic fast ions.Approximations applicable to realistic neutral beam distributions and modecharacteristics observed in spherical tokamaks enable the derivation ofmarginal stability conditions for these modes. Such conditions successfullyreproduce the stability boundaries found from numerical integration of theexact expression for local fast ion drive/damping. Coupling between the CAE andGAE branches of the dispersion due to finite $\omega/\omega_{ci}$ and$k_\parallel/k_\perp$ is retained and found to be responsible for the existenceof the GAE instability via this resonance. Encouraging agreement isdemonstrated between the approximate stability criterion, simulation results,and a database of NSTX observations of co-CAEs.

Analytic stability boundaries for compressional and global Alfv\'en eigenmodes driven by fast ions. II. Interaction via Landau resonance