Theoretical analysis of BLM system for HLS II

Hefei Light Source (HLS) is being upgraded to HLS II. Its emittance will be much lower than before, therefore the Touschek scattering will increase significantly and become the dominant factor of beam loss. So it is necessary to build a new beam loss monitoring (BLM) system differed from the old one to obtain the quantity and position information of lost electrons. This information is useful in the commissioning, troubleshooting and beam lifetime studying for HLS II. This paper analyzes the distribution features of different kinds of lost electrons, introduces the new machine's operation parameters and discusses the way to choose proper monitoring positions. Base on these comprehensive analysis, a new BLM system for HLS II is proposed.