Investigation of the longitudinal component of an electron   electromagnetic field under condition of the shadowing effect
  In this paper we present the method and experimental results of the investigation of a longitudinal component of relativistic electron electromagnetic field in the shadow area of a transversal component. We show experimentally, that in a region, comparable with the formation length area no shadowing effect of the longitudinal component of relativistic electron electromagnetic field appears. This is important for understanding of possibility of the shadowing effect in Smith-Purcell radiation and some other radiation types. 
G.A. Naumenko, L.G. Sukhikh, Yu.A. Popov, M.V. Shevelev
physics.acc-ph physics.class-ph