Novel Adjustable Permanent Magnet Quadrupoles for the CLIC Drive Beam Decelerator

The CLIC Drive Beam Decelerator (DBD) requires 41,848 quadrupoles to keep the beam focused along its length. Due to the stringent heat load requirements of the CLIC tunnel, a permanent magnet (PM) design is under investigation in a collaboration between CERN and STFC Daresbury Laboratory. The design incorporates a novel method of adjustment based on moving PMs. To cover the full length of the decelerator, two families of quadrupoles have been designed. This paper outlines the challenges of building an adjustable PM quadrupole, and explains the features of the two designs and how they will meet the demanding specifications of the CLIC DBD.