2025/11/18 by M. Goossens, Marcel Goossens, Iñigo Arregui +11 · 1 voice
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Geomagnetism and Paleomagnetism Studies #Ionosphere and magnetosphere dynamics #Solar and Space Plasma Dynamics
paper · doi:10.1007/s41614-025-00207-5
crossref issued 2025/12/02 · crossref published 2025/12/02 · crossref published-online 2025/12/02 · openalex created_date 2025/12/02 · openalex publication_date 2025/12/02 · crossref created 2025/12/02 · crossref deposited 2025/12/02 · crossref indexed 2025/12/02 · openalex updated_date 2026/07/23
Non-uniformity plays an important role for MHD waves. For a uniform plasma of infinite extent the MHD waves can be subdivided in two classes with distinct properties. The first class contains the Alfvén waves. The Alfvén waves are incompressible and propagate parallel vorticity. They do not have a parallel component of displacement, they do not cause variations in pressure and are driven by magnetic tension only. The second class contains the magneto-sonic waves. They are compressible and have a parallel component of displacement. They do not propagate parallel vorticity and are driven by pressure and magnetic tension. In non-uniform plasmas the situation can be very different. The clear division between Alfvén waves and magneto-sonic waves is no longer present. In a given part of the equilibrium an MHD wave can strongly resemble a magneto-sonic wave with little or no resemblance to Alfvén waves; while in another part of the equilibrium the MHD wave is practically an Alfvén wave, which has the amazing property of being accompanied by variations in pressure.