Diamond Annual Review 2021/22

108 109 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 1 / 2 2 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 2 1 / 2 2 Figure 5. Prototype gradient bending magnet undergoing magnetic measurement using a stretched wire bench. Machine Operation and Development RichardWalker, Technical Director 2 021/22 was our 15 th year of operation, and like the previous year, continued to be influenced by the ongoing pandemic. The first Run of the period continued the restricted schedule of the previous year, with User Mode running from 09:00 Tuesday to 09:00 Saturday, with start-up/Machine Development on Mondays. However inmid-June, we resumed standard 6-day running, from 09:00Wednesday to 09:00 Tuesday interspersed with Machine Development days. A total of 189 days (4532 hours) were scheduled for User Mode operation, including 5 beamline start-up days. All operation was in standard multibunch mode (900 bunch train) with total current of 300 mA, there was no “hybrid”or “low-alpha”operation. The annual operating statistics are shown in Figure 1. The overall MTBF continued to be good at almost 108 hrs, and each of the five operating Runs achieved a MTBF in excess of 72 hrs, which is the target minimum. However, the 97.4% uptime was disappointingly below the target of 98%. We suffered from a few extended downtimes, two events associated with the cryo-plant accounted for 42% of the total downtime, while three further issues in other parts of the RF system contributed 23%, and a couple of power distribution events contributed 8%. Three-quarters of all beam trips were recovered in under 2 hrs, but with the above longer outages the overall MeanTimeTo Repair (MTTR) was 2.5 hours. Radiofrequency Developments Significant progress has been made with the RF upgrade programme which is aimed at increasing the resilience of machine operation. A 60 kW solid state amplifier has been installed and commissioned and will be used to power the already installed second booster RF cavity. The third normal conducting HOM-damped cavity was installed in the storage ring in March 2022. This will be powered by a new 120 kW solid state amplifier. Owing to travel restrictions, the Factory Acceptance Test of the amplifier which took place in December 2021 was witnessed via video link (Figure 2, left). As shown, full power operation was demonstrated even with 18 power transistors disconnected. The amplifier has now been installed at Diamond (Figure 2, right) and awaits the Site Acceptance Test. Insertion Device Developments Cryogenic permanent magnet undulators (CPMUs) provide an increase in photon flux for beamlines, especially in the hard X-ray region, by providing more magnetic field for a given operating gap using the enhanced performance of new permanent magnet materials at temperatures down to 77K (-196°C). Since the first Diamond designed and built device, CPMU-1, was installed for beamline I24 (ID24) in March 2020, three further CPMUs have been completed, and a fifth is under construction. CPMU-2 was installed as ID03 (see Figure 3), while CPMU-3 has replaced CPMU-1 as ID24, due to some unexpected problems with that device. CPMU-4 will shortly be installed as ID04 and CPMU-1, following repair, will be re-deployed as ID11 later this year. Figure 4 shows the improved X-ray flux from CPMU-2 compared to the previous insertion device for beamline I03, especially at higher photon energies. Diamond-II Update Significant progress has been made with the design of the Diamond-II machine upgrade in the last year during the TDR (Technical Design Report) phase, which is now nearing completion. The TDR was successfully reviewed at the beginning of March 2022 by the Diamond-II Machine Advisory Committee and is currently undergoing final editing. Several key decisions have been made in the last year: • the injection scheme will be a conventional 4-kicker + “thick/thin” septum for commissioning, refilling the machine and as a backup, while single bunch aperture sharing will be used during user operation for improved transparency of injection. • the standard fill pattern will consist of 5 bunch trains with 5 gaps of 7 buckets. • the 3rd harmonic cavity will be a passive superconducting “Super3HC”- type cavity. • the girders will be motorised under local control. • the linac energy will be increased from 100 MeV to 150 MeV, using 3 new shorter accelerating sections, tuned to the new storage ring and booster RF frequency. Prototyping of some of the key components for Diamond-II is underway. A prototype gradient dipole magnet has been built and is undergoing magnetic measurements (Figure 5). A full-scale prototype girder has been delivered and vacuum vessels for a complete girder vessel string have been ordered. Figure 1. Mean Time Between Failures (MTBF) and Uptime by operating year. Figure 2. left - 120 kW solid state amplifier Site Acceptance Test witnessed via video link, right – amplifier installed at Diamond. Figure 3. Insertion Device Group and CPMU-2 installed as ID03. Figure 4 . Photon intensity measured on the I03 beamline with CPMU-2 (black curves) and with the previous insertion device (red lines).