Possible upgrading of the SLS RF system for improving the beam lifetime

The RF system which was adopted for the SLS (Swiss Light Source) initial phase is based on the choice of conventional, already well-proven equipment. The use of superconducting (sc) cavities has been ruled out as a starting solution. However, for improving the beam lifetime in the storage ring (SR) when operating at very high brightness, the initial normal conducting (nc) system could be further complemented with idle (only-beam-driven) sc cavities. Within that scheme, two different approaches have been investigated: either doubling the fundamental RF voltage using one 500 MHz sc cavity, or lengthening the bunches with one (possibly two) third harmonic sc cavity(ies). These upgrading options are discussed here.