Analysis and testing of an alignment monitoring system for PIP-II superconducting cryomodules at Fermilab

Proton Improvement Plan II (PIP-II) is Fermilab’s plan to upgrade the particle accelerator complex. The linear accelerator (linac) consists of superconductive cavities, which accelerate the particles, and solenoids, needed to steer and to focus the beamline. Cavities and solenoids (also called coldmass assembly) are inserted into a unit called cryomodule (CM). CMs cool and insulate the coldmass assembly from the external environment at room temperature. Superconducting cryomodules use an optical monitoring system to check the alignment of internal components during assembly, testing and operation. This system consists of cameras, known as Boston CCD Angle Monitor “type H” (H-BCAM), and highly reflective targets installed on cavities and solenoids. H-BCAMs track the targets, tracing translations and rotations of the coldmass assembly, which must not exceed design constraints to not affect the cryomodules ability to increase the particles energy. In this thesis, the integration of the H-BCAMs and targets into the prototype High Beta 650 cryomodule (pHB650 CM) is discussed, along with the analysis of the data acquired to monitor the alignment. H-BCAMs and targets were also used during the test of a Single Spoke Resonator “type 2” cavity (SSR2), which takes place in the Spoke Test Cryostat (STC) facility at Fermilab. The test aims at checking the cavity functionality under nominal working conditions before its insertion into the CM. This contribution presents the integration of the H-BCAMs into the STC, which are tested for the first time under cryogenic conditions. Thermal and structural analyses were used, with Finite Element Method (FEM), to predict the cavity displacements, and to evaluate the power to supply to two film heaters to ensure that the H-BCAMs could be at room temperature during the test. Results showed that H-BCAMs need a proper installation and calibration to be a reliable instrument to check the alignment of superconductive cryomodules. Further development is needed to improve the cameras measurements for future cryomodules assembly. Prediction methods, based on Finite Element Analyses (FEA), proved to be corroborated techniques which can be used to estimate the quality of experimental data acquisitions.