DESIGN CONSIDERATIONS FOR A NEW WEAK-FIELD SOFT-X-RAY UNDULATOR FEL DRIVER FOR PEP

Design considerations and projected performance parameters for a novel variable-field undulator are reviewed. The design, which has no moving parts, features the absence of permeable or permanent magnet (PM) materials and is capable of generating light of arbitrary polarization with negligible coupling between the vertical and horizontal phase space distributions. The attainable field precision of the (iron-free) electromagnetic structure makes it suitable for high energy (> 4 GeV) FEL or optical klystron (OK) applications in straight sections approaching several hundred meters in length. While non-optimal in the amount of power required for rated operation, the configuration features maximal mechanical simplicity, resulting in a significantly less expensive structure than a conventional PM design.