Active damping of suspension wire violin modes in gravitational wave detectors

✍ Scribed by S.D Killbourn; K.D Skeldon; D.I Robertson; H Ward

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 458 KB
• Volume: 261
• Category: Article
• ISSN: 0375-9601
• DOI: 10.1016/s0375-9601(99)00596-4

✦ Synopsis

A technique is described to actively damp the fundamental violin mode resonances of the suspension wires used in the high-Q multi-stage pendulum systems found in interferometric gravitational wave detectors. The damping procedure utilises sensing signals and actuators that already exist in the control topology for such interferometers, making for very convenient practical implementation. An experimental demonstration of the damping technique applied to the double pendulum suspensions used in the Glasgow 10 m prototype interferometer is presented. The decay times of the violin modes associated with these suspensions, which occured typically at around 400 Hz, were reduced from of order 100 seconds to around 1 second or less without degrading the interferometer noise performance.