Simultaneous Multi-length Bunch Operation Mode Study For Hefei Light Source

The research about short bunches is more and more popular these years, result in the need for short bunches in storage rings. The traditional way to get short bunches in storage rings is to decrease the momentum compaction factor α by low-alpha optics, but the total current would decrease a lot to μA by the so-called "Low-Alpha" mode. Recently, a scheme with two superconducting RF cavities is designed to upgrade electron storage rings to multi-length bunches. With two new superconducting RF cavities, we could get multi-length bunches and a higher total current at the same time. However, there are different numbers of buckets in different storage rings in the world, which resulting some difference in realizing the scheme.In this paper, the Hefei Light Source (HLS) is given as an example for multi-length bunches design.At the same time, we find that the frequency and voltage of HLS is in a low value, leading to realizing the superconducting cavities by a single-cell structure, while most of other storage rings need a multi-cell structure. The single-cell structure could simplify the high order mode (HOM) problems, and also save a lot of money in building the superconducting cavities. Thus, Hefei Light Source could be the first storage ring to realize multi-length bunch design in the world.