Transverse beam stacking injection system for synchrotron light source booster synchrotrons

Beam intensity is a key performance parameter for particle accelerators. Modern high-performance storage rings demand injectors that can deliver large currents per injection cycle, which translates to an increase in machine size and consumed power. Therefore, it is justifiable to look for ways to increase the injector's performance while minimizing the size increase. We have investigated a number of ways to accumulate charge in a booster synchrotron and applied one of them to the NSLS-II booster. We have designed a scheme to transversely stack two bunch trains from the injector linac in the booster. In this paper we discuss this stacking scheme. The relevant booster dynamics are studied. The charge transport efficiency of the stacking scheme is studied in detail at injection and through a full booster ramp. Pulsed magnet requirements for the injection system and methods to achieve them are discussed. We show that the charge transport efficiency of the stacking scheme is similar to a single bunch train in the booster. This has become a critical design feature of the NSLS-II booster.