Design of low-impact impedances devices: the new proton synchrotron booster absorber scraper (PSBAS)

At CERN the HL-LHC (High Luminosity Large Hadron Collider) and the LIU (LHC Injection Upgrade) projects call for an increase in beam parameters such as energy, intensityand brightness. To achieve this goal the whole accelerator complex will be upgraded. Systems, equipment and devices need to be redesigned and rebuilt accounting for the demanding new beam features. In this framework device impedance is a key parameter. It is essential to evaluate and to minimize the impedance of the component during its early design phase. This avoids beam instabilities and minimizes beam losses and induced heating. In this paper we outline general guidelines for a low-impedance design and we show how to implement them in a real case, taking as example the design of the new Proton Synchrotron Booster Absorber Scraper (PSBAS). This is a key component aimed to remove the beam halo at the beginning of the LHC accelerator chain.