Author: Rendahl, T.F.
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Skywalker: Python Suite for Automated Photon Alignment at LCLS  
  • T.F. Rendahl, A.P. Rashed Ahmed, T.A. Wallace
    SLAC, Menlo Park, California, USA
  For the first seven years of its existence, the Linear Coherent Light Source (LCLS) at SLAC has been aligned manually by a combination of accelerator and beamline operators. In an effort to improve both the accuracy and speed of the initial delivery of X-ray light, a Python based automation suite Skywalker has been created to handle beam pointing to five unique experimental end stations. The module uses a configurable system identification algorithm to probe the parameter space of the mirror set, quickly building an accurate model without interrupting operation. The result is a robust model capable of precise movements without predefined assumptions. We will present the basic concepts and modules underlying Skywalker, analysis of the performance of the system at LCLS, and plans to extend the feature set to accommodate more intricate optical configurations.  
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THPHA129 Automated Contols for the Hard X-Ray Split & Delay System at the Linac Coherent Light Source 1678
  • A.P. Rashed Ahmed, M.C. Browne, D.L. Flath, K. Gumerlock, T.K. Johnson, L. Lee, Z.L. Lentz, T.F. Rendahl, H.S. Shi, H.H. Slepicka, Y. Sun, T.A. Wallace, D. Zhu
    SLAC, Menlo Park, California, USA
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
The hard x-ray split and delay (HXRSnD) system at the Linear Coherent Light Source (LCLS) was designed to allow for experiments requiring two-pulse based x-ray photon correlation spectroscopy. The system consists of eight silicon crystals split between two optical branches, with over 30 degrees of freedom. To maintain system stability and safety while easing system operation, we expand the LCLS Skywalker software suite to provide a python-based automation scheme that handles alignment, operations and engineer notification. Core safety systems such as collision avoidance are processed at the controller and Experimental Physics and Industrial Control System (EPICS) layer. Higher level functionality is implemented using a stack of open-source python packages (ophyd, bluesky, transitions) which provide a comprehensive and robust operational environment consisting of virtual motors, plans and finite state machines (FSM).
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