To reduce filling times and enable advanced injection schemes, it is desirable for the Diamond-II booster to provide high charge in both single and multi-bunch modes. The single bunch charge will be limited by short range wakefields in the booster, and long-range wakefields limit the charge for the multi-bunch trains. Due to the relatively low 100 MeV injection energy into the booster, the injected beam is susceptible to instabilities due to the very weak synchrotron radiation damping. In this paper, we present the simulation results carried out to estimate the single and multi-bunch charge thresholds in the Diamond-II booster including short and long range wakefields, RF cavity HOMs, and with physical apertures applied. Simulations results will also be presented that demonstrate the extracted multi-bunch charge could be increased by installing a transverse multi-bunch feedback (TMBF).

Boosters in synchrotron injector systems have traditionally had more relaxed designs than storage rings, and consequently impedance has not been considered an important factor in their designs. In 4th generation light sources like Diamond-II, it is desirable to increase the extracted charge per shot to reduce filling times and enable advanced injection schemes. As such, the vacuum chamber impedance becomes a significant design parameter. An impedance database has been created for the Diamond-II booster, using the same AT-style lattice concept as for the storage ring, to be used as input into particle tracking and other simulations. We present here an overview of the database, including details of significant components and current progress on engineering designs.