2014/10/24 by R J F Sgalla, Sgalla, R J F
Physics and Astronomy · #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Magnetic confinement fusion research #Plasma Physics (physics.plasm-ph) #Solar and Space Plasma Dynamics #physics.plasm-ph
paper · pdf · doi:10.48550/arxiv.1410.6827
20 pages, 1 figure
openalex publication_date 2014/10/24 · arxiv created 2014/10/29 · arxiv updated 2014/10/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A two fluid model with parallel viscosity is employed to derive the dispersion relation for electromagnetic geodesic acoustic modes (GAMs) in the presence of drift (diamagnetic) effects. Concerning the influence of the electron dynamics on the high frequency GAM, it is shown that the frequency of the electromagnetic GAM is independent of the equilibrium parallel current but, in contrast with purely electrostatic GAMs, significantly depends on the electron temperature gradient. The electromagnetic GAM may explain the discrepancy between the f∼ 40 kHz oscillation observed in TCABR [Yu. K. Kuznetsov et al., Nucl. Fusion \bf52, 063044 (2012)] and the former prediction for the electrostatic GAM frequency. The radial wave length associated with this oscillation, estimated presently from this analytical model, is λr∼ 25 cm, i. e., an order of magnitude higher than the usual value for zonal flows (ZFs).