Nonlinear Two-dimensional potential plasma wake waves
  The condition for potential description of the wake waves,generated by flat or cylindrical driving electron bunch in cold plasma is derived.   The two-dimensional nonlinear equation for potential valid for small values of that is obtained and solved by the separation of variables. Solutions in the form of cnoidal waves,existing behind the moving bunch at small values of vertical coordinate,are obtained.In particular,at some boundary conditions,corresponding to blow-out regime in the underdense plasma,the solution represents by a solitary nonlinear wave.   Approximate solution is also obtained using the method of multiple sacales.   The indications are obtained that the dependense of the amplitudes on longitudinal coordinate determines essentially,even in the first approximation,by driving bunch charge distribution.The wake wave amplitude can increase at some conditions along the longitudinal distance from the rear part of the bunch. 
A. Amatuni