Electro-Optic Sampling of Transient Fields from the passage of   High-Charge Electron Bunches
  When a relativistic electron bunch traverses a structure, strong electric fields are induced in its wake. We present measurements of the electric field as a function of time as measured at a fixed location in the beam line. For a 12 nC bunch of duration 4.2 ps FWHM, the peak field is measured >0.5 MV/m. Time resolution of ~5 ps is achieved using electro-optic sampling with a lithium tantalate (LiTaO_3) crystal and a short-pulse infrared laser synchronized to the beam. We present measurements under several different experimental conditions and discuss the influence of mode excitation in the structure. 
M. J. Fitch, A. C. Melissinos, P. L. Colestock, J.-P. Carneiro, H. T.   Edwards, W. H. Hartung