Beam orbit correction in the CLIC main linac using a small subset of correctors

Beam orbit correction in future linear colliders, such as the Compact Linear Collider (CLIC), is essential to mitigate the effect of accelerator element misalignment due to ground motion. The correction is performed using correctors distributed along the accelerator, based on the beam position monitor (BPM) readout from the preceding bunch train, with a train repetition frequency of 50 Hz. This paper presents the use of the MICADO algorithm [1] to select a subset of $N \approx 10$ correctors (from a total of 576) to be used for orbit correction in the designed 380 GeV centre-of-mass energy first-stage of CLIC. The optimisation of the number $N$ of correctors, the algorithm’s gain and the corrector step size is described, and the impact of a number of BPMs and correctors becoming unavailable is addressed. The application of a MICADO algorithm to perform dispersion free steering, by reducing the beam orbit difference between two beams with different energies, is discussed.