The Advanced Photon Source Upgrade (APS-U) will replace the more than 25 year old storage ring with a multibend achromat lattice. To alleviate beam lifetime and emittance concerns, the new storage ring will include a passive superconducting bunch-lengthening cavity whose voltage will be regulated via slow cavity tuning control. The reduction of the synchrotron tune will make the beam more susceptible to 60Hz line-harmonic related rf amplitude and phase noise in the main rf system, which will be addressed using LLRF adaptive notch filters. In the injectors, up to 10 times more charge must be provided with a Booster circumference that will no longer be rationally related to that of the storage ring. Upgrades to the LLRF in the injector chain include those for the fundamental and harmonic systems in the Particle Accumulator Ring as well as for the Booster, that will be compatible with the new timing scheme for bunch transfers. An overview and status update of the APS-U LLRF systems will be presented.
work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357