| The results of a comprehensive set of measurements on the first purposeful 1.21 GeV high tune, high field damping ring for the SLAC Linear Collider are reported.; Current dependent effects such as parasitic mode losses, head tail instabilities, synchrotron and betatron frequency shifts were measured to estimate the impedance. All results agree reasonably well with expectations and indicate no limitations to the design performance. A current of 55 mA (4 (.) 10('10) particles), which represents 80% of the design intensity, has been successfully stored in the ring with no sign of instabilities.; Some changes to the optics design that are being incorporated into the positron and electron damping rings now under construction are described. They are based on the operating experience with the present electron damping ring and include an improvement of the bending magnets and strengthening of the chromaticity correction scheme. As a consequence, the normalized equilibrium transverse emittance of the beam is expected to be 16 (mu)m rad.; Some properties of possible lattices for a future very high energy linear collider damping ring are discussed in the appendices. |
