G Travish, P. Frigola, J. Lim, J. Rosenzweig
Next-generation advanced-accelerators such as the PWFA, and beam-radiation interactions such as inverse-Compton scattering, depend on increased beam-density to achieve superior results. The photoinjector has enabled the production of high-brightness beams that are desirable for experiments with critical dependencies on bunch length and emittance. Along with the production of shorter and lower-emittance beams, comes the need to produce shorter focal-lengths (beta-functions). An approach to creating strong focusing-channels using high field, small-bore permanent-magnet quadrupoles (PMQs) has been followed by the authors. A focusing system using three PMQs, each composed of 16 Nd-Fe-B sectors in a Halbach geometry has been installed in the PLEIADES inverse-Compton experiment. As the magnets are of a fixed field-strength, the focusing system is tuned by adjusting the position of the three magnets along the beamline axis. This presentation covers the details of the focusing system, experimental experience, and implications for future experiments with an emphasis on advanced accelerators.
R. J. England, P. Musumeci, G. Travish, J. B. Rosenzweig, R. Yoder
A ramped electron bunch (i.e. one having a current density which rises linearly from the head to the tail and then drops sharply to zero) has been predicted to be an ideal drive beam for the plasma wake field accelerator due to the large transformer ratio it is capable of generating. A scheme was recently proposed for the creation of a relativistic electron bunch that approximates a ramped current profile [England, et al., AIP Conf. Proc. 647, p.884 (2002)], using a dogleg or dispersionless translating section as a bunch compressor. An experiment is underway at the Neptune laboratory using this scheme to create such a beam. The diagnostic being developed for measuring the temporal profile of the beam is an X-Band transverse deflecting mode cavity.