Measurement, Control and Minimization of Thermal Shift in Superconducting Devices

Abstract

Matthew T. Kasa, Jaromir M. Penicka, Emil M. Traktenberg, Scott N. Wesling (APS), Zachary A. Conway, Sang-Hoon Kim, and Peter N. Ostroumov (ATLAS), Argonne National Laboratory uperconducting (SC) magnetic and SC radio-frequency (SRF) devices designed for use in particle accelerators present challenging alignment problems. These devices are assembled and aligned at room temperature but operate at 2 to 4 Kelvin (K), with thermal offsets being large relative to the desired alignment tolerances. Unique solutions have been developed for controlling and minimizing the thermal shift, including utilization of materials that expand under cooling to compensate for contraction and kinematic couplings. Measurement of the thermal shift within SC devices is performed using both optical telescopes and laser instruments, typically through a parallel plate vacuum glass window. This article presents techniques developed at Argonne National Laboratory for measuring, controlling, and minimizing thermal shift in SC devices at both the Advanced Photon Source (APS) and the Argonne Tandem Linear Accelerator System (ATLAS). 4 THE JOURNAL OF THE CMSC/AUTUMN 2015