*** 9704039 Sobenin This Small Business Innovation Research Phase II project is for the construction/testing of an accelerating-focusing Rectangular Cavity Biperiodic Structure (RCBS) to be used in an electron Race Track Microtron (RTM). Circular cross section cavities produce weak radial focusing of relativistic electrons. In rectangular cross section cavities, the balance between transverse electric and magnetic forces acting on these electrons is changed so that there is substantially increased focusing in one transverse direction and weak defocusing in the other. In Phase I the rectangular cavity focusing strengths were further increased by replacing circular beam holes with rectangular beam slots. Methods were also developed to optimize these rectangular accelerating-focusing structures by varying both the cavity and beam aperture dimensions, thus allowing a beam to be tailored to a specific application. Introducing a RCBS into an RTM allowed the so-called 1st orbit problem to be elegantly solved and assisted in obtaining appropriate beam optics, while the impact of space charge effects were few and negligible. Thus, in Phase II the RCBS design parameters will be optimized for a compact 70 MeV prototype RTM. This structure will be manufactured, tuned, and its electrodynamic characteristics measured and then it will be subjected it to a full range of field tests. Commercial applications of RCBS in addition to those in RTMS, include high-power Continuous Wave Electron Linacs (CWEL), high charge-per-bunch Free Electron Laser (FEL) drivers, and electron-positron linear colliders.
