Longitudinal Beam Shaping and Compression Scheme for the UCLA Neptune Laboratory

We are developing a new beamline which will serve as a venue for future beamplasma interaction experiments using the 14MeV electron beam produced by the UCLA Neptune 1.625-cell photoinjector and PWT linac. An examination of the first and second-order optics indicates that when certain nonlinear effects are minimized through the use of sextupole magnets, the longitudinal dispersion is dominated by a negative R56Simulations using the matrix transport code ELEGANT indicate that for an appropriately chirped initial beam, this beamline can be used to create a ramped picosecond to sub-picosecond beam that is ideal for driving large amplitude wake fields in a plasma and producing high transformer ratios.