LLO MC2 Violin Mode Q

Document #:

LIGO-T1200418-v4

Document type:

T - Technical notes

Abstract:

This is a writeup of a quick calculation to understand the measured violin mode Q of the MC2 suspension at LLO but is applicable to all HSTS. The interesting conclusion is that the violin mode Q is dominated by thermoelastic damping which has its peak nearby.

Files in Document:

• T1200418-v4.pdf (1.9 MB)

Other Files:

• T1200418-v3.nb (417.0 kB)
• T1200418-v4.docx (1.4 MB)
• hststhermalnoise.pdf (17.7 kB)
• frequency vs. sus thermal noise displacement ("Stock" parameters) (TripleLite2_mark_barton_20120120hstsMC2damp_stockTN.m, 62.3 kB)
• frequency vs. sus thermal noise displacement (Fit to measurement) (TripleLite2_mark_barton_20120120hstsMC2damp_fittedTN.m, 62.3 kB)

Topics:

• Subsystem Test
• Integration
• Suspensions
• Modelling

Authors:

• Mark Barton
• Keiko Kokeyama

Keywords:

MC2 HSTS SUS suspensions violin_mode

Notes and Changes:

Various refinements suggested by Jeff K, including a calculation of net thermal noise. Incorporate refitted Q’s from LLO alog 5280.

v4: Corrected typo error in equation (1.8) in docx and pdf files (radius has been replaced by diameter). This does not affect results. (Norna, 9th August 2014)

Related Documents:

• LIGO-T070101: Dissipation Dilution
• LIGO-T080096: Wire Attachment Points and Flexure Corrections
• LIGO-T0900435: HAM Small Triple Suspension (HSTS) Final Design Document
• LIGO-D020700: HSTS Overall Assembly

Referenced by:

• LIGO-T1300926-v2: HLTS Violin Mode Q
• LIGO-T1300876-v4: Violin Mode Frequency/Q Summary as predicted by Models