Vibration Analysis of Cryogenically Cooled Accelerating Structures

Program Document ·

OSTI ID:2371576

Dhar, Ankur ^[1]

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1. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States), TID RFAR Applied Electromagnet

The Cool Copper Collider (C3) represents a novel path for achieving a future collider within the near future. Its conceptual design pushes the lim- its of NCRF technology, through the use of both distributed coupling and cryogenically cooled structures. These accelerating structures are cooled via liquid nitrogen vaporization, which can generate minute displacements to the structure’s alignment. Characterizing sources of misalignment from ex- ternal vibrations is a crucial process for this accelerator’s design. In order to accurately characterize these displacements, we validated techniques for measuring displacement of a structure immersed in liquid nitrogen. We used a prototype C3 structure with a hollow dielectric rod threaded with resis- tive molybdenum wires inserted along the beam pipe running the full length of the structure. Displacement measurements were then conducted as the dissipated power was slowly increased up to 2000 W of heat. Based on ac- celerometer data, we found that as heater power is increased, significant displacement around 40 Hz, 150 Hz, and 300 Hz would increase as well. None of these peaks are of major concern, since the 40 Hz peak can be corrected for with beam based feedback, while the other peaks were significantly lower in magnitude compared to lower frequency perturbations. These initial exper- iments were the first step in understanding the types of perturbations that liquid nitrogen bubbling can induce on a submerged accelerating structure due to RF heating. These initial results show displacements of less than 1 µm when up to 2000 W is dissipated within a meter-long copper structure.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States), TID RFAR Applied Electromagnet
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 2371576
• Report Number(s): SLAC-PUB-17776
• Country of Publication: United States
• Language: English