Magnetohydrodynamic waveguide/resonator for Pc3 ULF pulsations at cusp latitudes
© The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences. 1999
Received: 9 April 1999
Accepted: 3 June 1999
Published: 6 June 2014
We present a possible theoretical model for the generation of travelling Alfven waves by external compressional disturbances in a two-dimensional inhomogeneous plasma. The transformation of a compressional wave mode into Alfven waves guided by the magnetic field is considered in a region with decreased Alfven velocity. This region represents, on the one hand, a waveguide for compressional oscillations, and on the other hand, a resonator with opaque boundaries for Alfven waves. The wave transformation is most effective in a resonant case, when the frequency of a compressional mode approaches the local Alfven frequency of a resonator. This model is applied to the interpretation of Pc3 observations in the cusp region. The mechanism can ensure the selective amplification of magnetosheath turbulence in the Pc3 band in the high-latitude cusp.