Overview of the Beams from the Injectors

The injectors have delivered different beam types for luminosity production in the LHC during the 2017 run. Besides the nominal beam with 25 ns spacing and 72 bunches at PS extraction, the batch-compression-merging-splitting (BCMS) beam with multiples of 48 bunches at extraction from the SPS has been produced. The reduced number of bunches per batch from the PS is compensated by almost twice as smaller transverse emittance. The vacuum related issues in the LHC (16L2 cell) could be mitigated by switching to the so-called 8b4e beam, where mini- batches of 8 bunches are followed by 4 empty bunch positions in between. Thanks to the flexibility of the injectors, a higher brightness version of the 8b4e has been prepared to quickly react to the needs of the LHC. In this paper, an overview of the beams from the injector complex is given, describing how the beams are produced and summarizing their characteristics, achieved performance and specific limitations. In view of the operation in 2018, the expected beam parameters are presented, as well as a reminder of possible alternative beam types from the injectors.