ANL, Argonne, Illinois, USA
The new orbit feedback system required for the APS multi-bend acromat (MBA) ring must meet challenging beam stability requirements. The AC stability requirement is to correct rms beam motion to 10 \% the rms beam size at the insertion device source points from 0.01 to 1000 Hz. The vertical plane represents the biggest challenge for AC stability which is required to be 400 nm rms for a 4 micron vertical beam size. In addition long term drift over a period of 7 days is required to be 1 micron or less at insertion device BPMs and 2 microns for arc bpms. We present test results of the MBA prototype orbit feedback controller (FBC) in the APS storage ring. In this test, four insertion device BPMs were configured to send data to the FBC for processing into four fast corrector setpoints. The configuration of four bpms and four fast correctors creates a 4-bump and the configuration of fast correctors is similar to what will be implemented in the MBA ring. We report on performance benefits of increasing the sampling rate by a factor of 15 to 22.6 kHz over the existing APS orbit feedback system, limitations due to existing storage ring hardware and MBA orbit feedback design.
ANL, Argonne, Illinois, USA
The Advanced Photon Source (APS) is developing the design of a multi-bend achromat (MBA) lattice based storage ring as the next major upgrade, featuring a 20-fold reduction in emittance. Combining the reduction of beta functions, the electron beam sizes at bend magnet sources may be reduced to reach 5 - 10 μm for 10% vertical coupling. The x-ray pinhole camera currently used for beam size monitoring will not be adequate for the new task. By increasing the operating photon energy to 120 keV or higher, the pinhole camera's resolution is expected to reach below 4 μm. The peak height of the pinhole image will be used to monitor relative changes of the beam sizes and enable the feedback control of the emittance. We present the computer simulation and the design of a prototype beam size monitor for the APS storage ring.