  The anisotropy due to a magnetic field is shown to result in significant
changes in Langmuir collapse. Using a variational approach, the quasi-classical
collapse phenomenon is investigated analytically.
  A hierarchy of quasi-classical collapses is determined, along with the
structure of a field in the proximity of a stationary singularity that is
sustained by the continuous absorption of wave energy from a wave packet.

Plasma Physics;Pattern Formation and Solitons