Experimental Observation of Energy Modulation in Electron Beams Passing   Through Terahertz Dielectric Wakefield Structures
  We report observation of a strong wakefield induced energy modulation in an energy-chirped electron bunch passing through a dielectric-lined waveguide. This modulation can be effectively converted into a spatial modulation forming micro-bunches with a periodicity of 0.5 - 1 picosecond, hence capable of driving coherent THz radiation. The experimental results agree well with theoretical predictions. 
S. Antipov, C. Jing, M. Fedurin, W. Gai, A. Kanareykin, K. Kusche, P.   Schoessow, V. Yakimenko, A. Zholents
physics.acc-ph