ANL, Argonne, Illinois, USA
Three s-band RF guns are installed at the front end of the Advanced Photon Source (APS) linac: two thermionic cathode guns (RG2 and RG1), and one Photo-Cathode Gun (PCG). During normal operations, RG2 provides electron beams for the storage ring to generate x-rays for APS users. The PCG generates high brightness electron beams that can be accelerated through the APS linac and transported into the Linac Extension Area (LEA) for advanced accelerator technology and beam physics experiments. The alternating acceleration of the RG2 and PCG beam in the linac is possible, as most of the time, RG2 beam is only needed for ~20 seconds every two minutes. This mode of interleaving operation of RG2 and PCG beams through the APS linac requires some modifications/additions to several systems of the linac, including RF, magnets, controls and Access Control Interlock System etc. In this paper we report our interleaving design and present the commissioning results of the two beam interleaving operation.
ANL, Argonne, Illinois, USA
BNL, Upton, Long Island, New York, USA
Fermilab, Batavia, Illinois, USA
Next-generation, high-performance storage ring light sources based on multibend achromat optics will require on-axis injection because of the extremely small dynamic aperture. Injectors will need to supply full-current bunch replacement in the ring with high single-bunch charge for swap-out. For upgrades of existing light sources, such as the Advanced Photon Source Upgrade (APS-U), it is economical to retain the existing injector infrastructure and make appropriate improvements. The challenges to these improvements include achieving high single-bunch charge in the presence of instabilities, beam loading, charge stability and reliability. In this paper, we discuss the rationale for the injector upgrades chosen for APS-U, as well as backup and potential alternate schemes. To date, we have achieved single-bunch charge from the injectors that doubles the original design value, and have a goal to achieve about three times the original design value.
