Dispersion und Absorption transversaler Schallwellen im Magnetfeld

The propagation velocity and absorption of transverse ultrasonic waves have bsen measured in a polycristalline metallic probe as functions of a magnetic field parallel to the direction of propagation. In agreement with the macroscopic theory, these measurements showed, that the propagation velocity was increased by the magnetic field for frequencies below a transition frequency characteristic for the medium. In case of high frequencies the magnetic field causes an absorption. In the dispersion region characterized by the transition frequency, the magnetohydrodynamic Reynolds number is of order one and the magnetically induced changes in propagation velocity and absorption are strongly frequency dependent.