Lee, S.H. Doran, D.S. Jansma, W.G. Siy, A.E. Sorsher, S. Suthar, K.J. Trakhtenberg, E. Waldschmidt, G.J. Zholents, A. JACoW Publishing Geneva, Switzerland 2673-5520 978-3-95450-229-5 10.18429/JACoW-MEDSI2020-WEPB05 English 276-278 vacuum GUI wakefield quadrupole electron Contribution to a conference proceedings 2021 2021-10 https://doi.org/10.18429/JACoW-MEDSI2020-WEPB05 https://jacow.org/medsi2020/papers/wepb05.pdf Argonne National Laboratory is developing a Sub-THz AcceleRator (A-STAR) for a future multiuser x-ray free electron laser facility. The A-STAR machine will utilize a compact collinear wakefield accelerator (CWA) based on a miniature copper (Cu) corrugated waveguide as proposed*. The accelerator is designed to operate at a 20-kHz bunch repetition rate and will utilize the 180-GHz wakefield of a 10-nC electron drive bunch with a field gradient of 100 MVm’1 to accelerate a 0.3-nC electron witness bunch to 5 GeV. In this paper, we discuss specific challenges in the mechanical design of the CWA vacuum chamber module. The module consists of series of small quadrupole magnets with a high magnetic field gradient that houses a 2-mm diameter and 0.5-m-long corrugated tubing with brazed water-cooling channels and a transition section. The 45-mm-long transition section is used to extract the wakefield and to house a beam position monitor, a bellows assembly and a port to connect a vacuum pump. The CWA vacuum chamber module requires four to five brazing steps with filler metals of successively lower temperatures to maintain the integrity of previously brazed joints.