Resonant Plasma Wave Growth and Monoenergetic Electron Beam Production   using Collinear High-Intensity Ultrashort Laser Pulses
  The resonant generation of relativistic plasma waves and plasma wave guiding by two co-propagating laser pulses has been studied. By proper timing between guiding and driver pulses, a resonant interaction occurs, which generates a high-amplitude plasma wave over a longer length than is possible with either of the laser pulses individually. The growth of the plasma wave is inferred by the measurement of monoenergetic electron beams with low divergence that are not measured by using either of the pulses individually. This scheme can be easily implemented, and allows more control of the interaction than is available to the single pulse scheme. 
A. G. R. Thomas, C. D. Murphy, S. P. D. Mangles, A. E. Dangor, P.   Foster, J. G. Gallagher, D. A. Jaroszynski, P. A. Norrey...