Controlling the generation of high frequency electromagnetic pulses with   relativistic flying mirrors using an inhomogeneous plasma
  A method for the controlled generation of intense high frequency electromagnetic fields by a breaking Langmuir wave (relativistic flying mirrors) in a gradually inhomogeneous plasma is proposed. The wave breaking threshold depends on the local plasma density gradient. Compression, chirping and frequency multiplication of an electromagnetic wave reflected from relativistic mirrors is demonstrated using Particle-In-Cell simulations. Adjusting the shape of the density profile enables control of the reflected light properties. 
Mathieu Lobet, Masaki Kando, James K. Koga, Timur Zh. Esirkepov,   Tatsufumi Nakamura, Alexander S. Pirozhkov, and Sergei V....
physics.plasm-ph