Phase matched plasma wakefield photon acceleration

We present Phase Matched Plasma Wakefield Photon Acceleration (PMPA), a scheme for dephasingless photon acceleration in a particle-beam-driven wake. Electromagnetic radiation seeing a decreasing plasma gradient shifts up in frequency. In PMPA, a laser pulse is situated in the wake of a relativistic electron bunch so that it sees a decreasing density gradient. Using a tapered density profile to keep witness laser pulse at the phase in the wake where the density is decreasing, simulations suggest that the frequency of the witness pulse can be shifted up by a factor of 5-10.