2004/10/22 by Tohru Hada, Hada, Tohru, Shuichi Matsukiyo +4
Physics and Astronomy · #Dust and Plasma Wave Phenomena #FOS: Physical sciences #Ionosphere and magnetosphere dynamics #Magnetic confinement fusion research #Plasma Physics (physics.plasm-ph) #physics.plasm-ph
paper · pdf · doi:10.48550/arxiv.physics/0410203
12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France)
arxiv created 2004/10/22 · openalex publication_date 2004/10/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The linear dispersion relation of a finite amplitude, parallel, circularly polarized Alfvén wave in a relativistic electron-positron plasma is derived. In the nonrelativistic regime, the dispersion relation has two branches, one electromagnetic wave, with a low frequency cutoff at √(1+2ωp2/Ωp2) (where ωp=(4πn e2/m)1/2 is the electron/positron plasma frequency), and an Alfvén wave, with high frequency cutoff at the positron gyrofrequency Ωp. There is only one forward propagating mode for a given frequency. However, due to relativistic effects, there is no low frequency cutoff for the electromagnetic branch, and there appears a critical wave number above which the Alfvén wave ceases to exist. This critical wave number is given by ckc/Ωp=a/η, where a=ωp2/Ωp2 and η is the ratio between the Alfvén wave magnetic field amplitude and the background magnetic field. In this case, for each frequency in the Alfvén branch, two additional forward propagating modes exist with equal frequency. A simple numerical example is studied: by numerically solving the coupled system of fluid and Maxwell equations, normal incidence of a finite amplitude Alfvén wave on an interface between two electron-positron plasmas of different densities is considered.