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A C C E L E R A T O R A N D S O U R C E

The Accelerator and Source Division (ASD) is in charge of the production of synchrotron light from the Extremely Brilliant Source (EBS), the Phase- II Upgrade of ESRF s 6 GeV storage ring. For over two years, since 25 August 2020, the EBS has been operating in User Service Mode (USM), following its successful construction and commissioning. With the efforts of the ASD, and of the Instrumentation and Services Development Division (ISDD) and the Technical Infrastructure Division (TID), and thanks to preventive maintenance on all the hardware systems that consolidate USM operation, remarkable results in the USM operation of EBS have been achieved, with the beam availability increasing from 96.35% in 2021 to 99.06% in 2022. The Mean Time Between Failures (MTBF) also reached 88.5 hours in the period of USM operation in 2022, and the Mean Duration of a Failure (MDF) was less than one hour (~50 mins). A total of 5490 hours of beam was officially scheduled for delivery to users in 2022, which also reaches the level of beam delivery time before the pandemic. However, 2022 was the first year of EBS with a full USM operation schedule in the pandemic period. In addition to EBS operation, much of the Division s development work in 2022 has focused on the consolidation and sustainability of EBS operation and improvements in beam performance.

With the aim of reaching nominal beam currents in the timing modes (4-bunch and 16-bunch filling patterns), the ASD replaced the four injection kickers (which were found to be problematic in terms of heating when the single- bunch current was increased) with re-coated ceramic chambers with much lower resistances than the original ones. This measure led to an increase in beam current from 35 mA to 75 mA in 16-bunch mode and from 20 mA to 40 mA in 4-bunch mode in 2022. The procurement of the newly designed kicker and shaker ceramic chambers was contracted to the company SOLCERA for manufacture, after technical problems encountered on the prototype were resolved.

The Hotswap system, which covers all the power supplies to the quadrupoles around the storage ring, and which was already connected within the current power supply system in 2021, was deemed ready for deployment in full operation by the end of 2022, after tests carried out during machine-dedicated time (MDTs). The development of the TANGO controls and user interface for the Hotswap system were completed in 2022, resulting in the improvement of the robustness of the system.

The replacement of the klystrons operating with the RF cavities in the storage ring of EBS, the solid state amplifier (SSA) project, is still in the procurement stage of SSAs. The whole project is making good progress, with infrastructure related to the SSAs also under construction. A fourth harmonic RF system is still in its design stage, although some of the technical challenges were overcome in 2022. It will be helpful to increase the Touschek beam lifetime in the operation of the timing modes with nominal beam currents, and, in the meantime, to reduce the parasitic heating on the accelerator vacuum elements.

The injection perturbation and the injection efficiency are crucial to users and are continually tuned after the re-alignment of the TL2 transfer line, and to lower the RF voltage of the booster. As a result, an injection efficiency of 80% was resumed. The physics design, together