Abstract


  FAST SPATIAL DAMPING BY RESONANT ABSORPTION OF COUNTER-STREAMING WAVES IN SLOW FLOWS

  M. Goossens, KU Leuven, Marcel.Goossens@wis.kuleuven.be
  R. Soler, UIB, roberto.soler@uib.es
  T. Van Doorsselaere, KU Leuven, tom.vandoorsselaere@wis.kuleuven.be

This presentation reports on an analysis of the spatial damping by resonant absorption of propagating MHD Alfvenic waves in the presence of flows. Propagating waves are ubiquitous in the solar atmosphere. A recent development is the detection of propagating MHD waves in the presence of flows. Both forward and backward propagating (or counter-streaming)waves have been observed. It turns out that counter-streaming waves are difficult to observe. Our analysis shows that the spatial damping by resonant absorption is different for forward and backward propagating waves. It is far stronger for counter-streaming waves than for forward propagating waves. Even for slow sub-Alfvenic flows the damping length of the backward propagating wave is substantially shorter than that of the forward propagating wave. This provides a natural explanation for the scarcity of observations on counter-streaming Alfvenic waves.