TOP-UP OPERATION OF SPring-8 STORAGE RING WITH LOW-EMITTANCE OPTICS

We have succeeded in providing stable and three-times more brilliant x-ray beams to users by combining top-up operation with low-emittance optics. The optics with the low emittance of 3nmrad was firstly applied to the user operation in November 2002. Although the low emittance provided the brilliant x-ray, the extremely short beam lifetime much disturbed the precise experiments. Moreover, the aborted electron beam damaged the part of vacuum chamber at the beam injection section. The low-emittance operation was thus suspended in October 2003. By improving design of the vacuum chamber and introducing the top-up injection, the problems for the stable operation were resolved and then, the top-up operation with the low-emittance optics has been firstly achieved at SPring8. This paper illustrates how we achieved this sophisticated operation by explaining the following three essential subjects: (1) our concept of increasing brilliance of x-ray beams and solution to some problems in realizing the lowemittance optics, (2) protection of vacuum chamber from aborted electron beam, and (3) introduction of top-up injection. The obtained performance is also described in the paper.