[en] A conceptual design for a soft x-ray free-electron laser (FEL) using a short-pulsed, high energy near infrared laser undulator and a low-emittance modest-energy (∼170 MeV) electron beam is described. This low-cost design uses the laser undulator beam in a nearly copropagating fashion with respect to the electron beam, instead of the traditional ‘head-on’ fashion. The nearly copropagating geometry reduces the Doppler shift of scattered radiation to yield soft, rather than hard x-rays. To increase the FEL gain a sheared laser pulse from a Ti : sapphire or other broadband laser is used to extend the otherwise short interaction time of the nearly copropagating laser undulator beam with a relativistic electron beam. (paper)

[en] We review experimental observations of space-charge effects and collective phenomena in charged particle beams for accelerator applications. These include halo formation and emittance growth, bunch profile evolution, space-charge waves, and longitudinal instabilities. We also report on the development of the University of Maryland Electron Ring for the study of space-charge physics in a circular lattice