IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 29, NO. 5, AUGUST 2019 4100405 Power Test of the Second-Generation Compact Linear Collider (CLIC) Nb 3 Sn Damping Wiggler Short Model Michal Duda , Franco Mangiarotti , Marta Bajko , Axel Bernhard , Vincent Desbiolles, Paolo Ferracin , Jerome Feuvrier, Laura Garcia Fajardo , Jose Lorenzo , Jacky Mazet, Juan Carlos P´ erez, Daniel Schoerling , and Gerard Willering Abstract—In the frame of the compact linear collider project, a high-field short-period superconducting damping wigglers will be required to reduce the emittance of the electron and positron beams. The use of Nb 3 Sn as superconducting material is being investigated, as a valid option for its smaller size and increased working margin. At CERN, Geneva, Switzerland, a second Nb 3 Sn damping wiggler short model has been developed, assembled, and tested. In this paper, the cold power test of that magnet is discussed in terms of training, quench detection, protection, endurance, and other tests. Index Terms—Superconducting damping wigglers, cold powering tests, quench protection. I. INTRODUCTION T HE Compact Linear Collider (CLIC) is a concept for future high luminosity two-beam accelerator colliding electrons and positrons. To achieve its design energy of several TeV at the collision point, the emittance of the beams must be reduced in the Damping Rings [1], [2]. It has been already confirmed that use of superconducting damping wigglers in a compact ring within the machine pulse of 20 ms will meet all the requirements [3]–[5]. The first Nb 3 Sn five-coil damping wiggler model has been developed, manufactured, and tested at CERN in 2012. Because of its insufficient electrical insulation, shorts to ground were detected and the tests were interrupted for safety reasons [6]. The second model with reduced period length and increased Manuscript received October 30, 2018; accepted January 29, 2019. Date of publication January 31, 2019; date of current version February 21, 2019. (Corresponding author: Michal Duda.) M. Duda is with the Henryk Niewodnicza´ nski Institute of Nuclear Physics, Polish Academy of Sciences, Krakow 31-342, Poland, and also with CERN, Geneva 1211, Switzerland. (e-mail:, michal.duda@ifj.edu.pl). F. Mangiarotti, M. Bajko, V. Desbiolles, P. Ferracin, J. Feuvrier, J. Mazet, J. C. P´ erez, D. Schoerling, and G. Willering are with CERN, Geneva 1211, Switzerland. A. Bernhard is with the Karlsruhe Institute of Technology, Karlsruhe 76131, Germany. L. Garcia Fajardo is with Lawrence Berkeley National Laboratory, Berkeley, CA 94720 USA. J. Lorenzo was with CERN, Geneva 1211, Switzerland. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TASC.2019.2896774 Fig. 1. The five-coil wiggler model: (left) 3D view, (right) final wiggler model before cold powering test. peak field in the gap was designed and produced in 2016 [7]. This paper presents results of the first power test of a new design model performed end of 2017. II. MAGNET CHARACTERISTICS A. Magnet Fabrication The wiggler coils were wounded with a single OST-RRP Nb 3 Sn wire of 0.85 mm diameter with a 70 μm S2-glass braid electrical insulation. The fraction of superconductor in this wire is 45.5% with a filament size of 48 μm. In order to improve electrical separation between iron poles and coils, an additional layer of 500 μm fiberglass was used. The five coils were aligned and clamped together using a dedicated assembly tooling and later impregnated with epoxy resin (see Fig. 1). The details of the upgraded design and improved manufacturing process are discussed in [7]. B. Magnet Parameters The five-coil wiggler model has a width of 0.3 m, a length of 0.1 m, and weights 10 kg. The short sample limits for the wire at 4.2 K and 1.9 K are 1120 A and 1200 A respectively; it corresponds to the maximum stored energy of 15-17 kJ, and a peak field of 9.4 T (see Fig. 2). From the technological point of view the magnet working point should be below 80% of the critical current and therefore maximum operating current is 850 A and ultimate current of 896 A [7]. The design inductance 1051-8223 © 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications standards/publications/rights/index.html for more information.