Operation and Performance of the University of Wisconsin - Physical Sciences Laboratory Electron Storage Ring

A 240 MeV electron storage ring has been in operation at the Physical Sciences Laboratory of the University of Wisconsin for one year. The storage ring injector is a 50 MeV FFAG electron synchrotron. The bunched beam from the synchrotron is injected into the storage ring in a single turn. Radio-frequency capture is accomplished by using the signal from the bunched beam as the master oscillator during capture. Using this method, high capture efficiency is achieved. A useful consequence of the method of radio-frequency capture is the damping of the coherent synchrotron oscillation instability. The beam may be accelerated, or decelerated, to any energy within the capability of the ring - 10 MeV to 240 MeV. The vacuum system operates at a pressure in the mid 10-10 range allowing lifetimes of many hours for low intensity beams. During the first year of operation several interesting effects have been observed. Among these were photo etching of metal from the vacuum chamber by synchrotron radiation and enhanced beam loss due to scattering from ions trapped in the electron beam. The beam also exhibits a transverse coherent instability that violates the Courant-Sessler criteria for stability.