Ground Vibration Induced Motion of the Filter Cavity Tube (FCT) Baffles

Document #:

LIGO-T2000280-v2

Document type:

T - Technical notes

Abstract:

Ground vibrational motion induces motion of the baffles within the filter cavity tube (FCT), which in turn may cause scattered light noise in the frequency dependent squeezed light system. The purpose of this memo is to present a dynamic analysis of the FCT, including its supports and installed baffles, in order to calculate the baffle motion response to ground vibration. The measured ground motion spectrum at the LIGO observatories, LIGO-T1500224, was used to estimate the motion of the FCT baffles.

This version of the dynamic analysis of the FCT assembly is based on the conceptual design of the baffles, LIGO-E2000177-v1 and LIGO-D1900424-v2, and the conceptual design of the FCT supports, LIGO-T2000002. As the designs mature this analysis may be updated.

Note: To see the mode shape videos, open the MS Word document (not the pdf).

Files in Document:

• T2000280-v2 ground vibration induced motion of the Fil...pdf (1.8 MB)

Other Files:

• FEA A+ FCT assy 3-tubes, spring bellows with baffles ...wbpz (49.7 MB)
• FEA FCT assy 3 with baffles (no bolts).zip (1.8 MB)
• T2000280-v2 FCT baffle psds.xlsx (3.2 MB)
• T2000280-v2 ground vibration induced motion of the Fi...docx (22.3 MB)

Topics:

• System Engineering
• Vacuum

Authors:

• Dennis Coyne

Notes and Changes:

initial release (CDR level)
The Y-axis of Figures 14 through 19 was corrected to be 'ASD (m/rHz)'.
The Ansys archive file (*.wbpz) is without results included. (If results are included then the file is 9.5 GB in size.)
--> Service Request for cylinder supports question created by StephenA 2020.05.13 -SR 1958425111 by sappert@ligo.caltech.edu

Related Documents:

• LIGO-T2000002: A+ Filter Cavity Tube, Expansion Joints and Tube Supports: Conceptual Design and Requirements.

Referenced by:

• LIGO-T2000431-v4: Filter Cavity Tube (FCT) Support Loads