Elettra | Machine Elettra Parameters In 2024 and in the first semester of 2025 Elettra operated 24 hours/day, seven days a week delivering synchrotron light from IR to hard x-rays to 24 operating beam lines of which 9 were served from dipoles and 15 from many types of insertion devices such as such as planar, polarizing, superconducting including canted APPLE II type undulators occupying all the eleven available long straights while a dispersive short straight was also used for short insertion devices such as the one of 1 m long serving the TwinMic being an adjustable phase double short undulator (APU). Due to the increase of the energy costs also in 2024 the scheduled functioning time of Elettra was reduced to about 59%, thus the usual 5000 hours given to the experiments have been reduced to 2929 hours. At about 75% of users dedicated time Elettra operates at 2 GeV while for the remaining 25% at 2.4 GeV being the only facility to operated at two energies (both in top-up). The main operating modes were multi-bunch with a dark gap of 42 ns and hybrid (at 42% of the total user beam time) i.e. multi-bunch with one (for time resolved experiments) or two single bunches (distant 40 ns in a dark gap of 120 ns for pump and probe experiments). The operating intensities were 310 mA at 2 GeV and 160 mA at 2.4 GeV with 5 mA single bunch (es) added when in hybrid mode. In Fig. 1, the total availability including surges (interruptions of the power grid, green bars) is shown for the past 10 years of top-up operation. Another important number indicative of the reliability of a light source is the mean time between failures (mtbf, red bars). The number of surges is shown by the solid blue line (right y axis). Although the uptime for 2024 was as good as in previous years, an increase of the mtbf, indicating a very smooth functioning of the machine has been measured. Note that in 2018 the mtbf decreased due to balance loss of the magnet cooling system after a general maintenance; however, the beam dumps were of very small duration thus not affecting much the total uptime. In 2019 a decreased total availability was observed mainly because of an abnormal increase of power net surges due to unusually stormy weather. The longest period without a beam dump for 2024 was 200 hours. The top-up availability to the total user time for 2024 was 87% due to calibration drifts of the beam current DCCT thus the machine was functioning in the decay mode for 13% of the user beam time. However, it is considered to be downtime when in decay mode and below a given threshold of intensity (270 mA at 2 GeV and 130 mA at 2.4 GeV). The injectors themselves did not give any real downtime. The top-up contributed also to very good long- and short-term orbit stability. Currently the long term (2 to 5 days) was at ±5μm maximum while the short term (24 hours) at 2% of the beam size (1.7 horizontally and 1.2 μm vertically). A series of changes and developments were performed due to the Elettra 2.0. Those developments were identified as the ones that can serve both the actual and the next machine including: · Tests of the new spare gun electronics done with success, the new gun reached 80 kV with 1 A peak current and will also be used in Elettra 2.0, including also the functionality requests in grab cavities mode and is scheduled to replace mechanically the actual gun during the dark period (July 2024 - August 2026) . · Eight novel electron BPM front ends (E2BPM) with submicron resolution based on pilot tone compensation for Elettra 2.0 were installed in section 6 of Elettra and successfully used with beam within the control system. · A new and more powerful version of the actual global orbit feedback that is developed for Elettra 2.0 (GOF 2.0) was used on Elettra. This version acquires data up to 100 kHz and therefore corrects the orbit much more efficiently. · Many improvements in the injector chain including installation of spark detectors for the bpms of the BTS transfer line for a higher accuracy of the reading of the orbit, were implemented permitting thus to include the BBA technique also in the BTS. Also, the emittance swap technique in the booster was successfully tested on Elettra in view of its use for injecting Elettra 2.0. The Linac was completely refurbished with new wave guides, new high voltage power supplies, new gun electronics and new timing, including also the complete remake of the SF6 system. Developments Status The operational parameters of the Italian 2.4/2.0 GeV third generation light source Elettra are presented together with the latest developments. Elettra Highlights 2024–2025 144
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