Beam Coupling to Optical Scale Accelerating Structures

Current research efforts into structure based laser acceleration of electrons utilize beams from standard RF linacs. These beams must be coupled into very small structures with transverse dimensions comparable to the laser wavelength. To obtain decent transmission, a permanent magnet quadrupole (PMQ) triplet with a focusing gradient of 560 T/m is used to focus into the structure. Also of interest is the induced wakefield from the structure, useful for diagnosing potential accelerator structures or as novel radiation sources.