Control Systems Design for LCLS-II Fast Wire Scanners at SLAC National Accelerator Laboratory

One of the primary diagnostic tools for beam emittance measurement at the Linac Coherent Light Source II (LCLS-II), an upgrade of the SLAC National Accelerator Laboratory’s Linac Coherent Light Source (LCLS) facility, is the wire scanners. LCLS-II’s new Fast Wire Scanner (FWS) is based on a similar mechanical design of linear servo motor with position feedback from an incremental encoder as that for LCLS. With a high repetition rate of up to 1MHz from the superconducting accelerator of LCLSII, it is no longer sufficient to use point-to-point EPICScontrolled moves from wire to wire, as continued exposure will damage the wires. The system needs to perform onthe-fly scans, with a single position versus time profile calculated in advance and executed in a single coordinated motion by Aerotech Ensemble motion controller. The new fast wire scanner control system has several advantages over LCLS fast wire scanner controls with the capability to program safety features directly on the drive and integrate machine protection checks on an FPGA. This paper will focus on the software architecture and implementation for LCLS-II Fast Wire Scanners.