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An investigation of eddy-current damping of multi-stage pendulum suspensions for use in interferometric gravitational wave detectors

Plissi, M. V. and Torrie, C. I. and Barton, M. and Robertson, N. A. and Grant, A. and Cantley, C. A. and Strain, K. A. and Willems, P. A. and Romie, J. H. and Skeldon, K. D. and Perreur-Lloyd, M. M. and Jones, R. A. and Hough, J. (2004) An investigation of eddy-current damping of multi-stage pendulum suspensions for use in interferometric gravitational wave detectors. Review of Scientific Instruments, 75 (11). pp. 4516-4522. ISSN 0034-6748. http://resolver.caltech.edu/CaltechAUTHORS:PLIrsi04

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Abstract

In this article we discuss theoretical and experimental investigations of the use of eddy-current damping for multi-stage pendulum suspensions such as those intended for use in Advanced LIGO, the proposed upgrade to LIGO (the US laser interferometric gravitational-wave observatory). The design of these suspensions is based on the triple pendulum suspension design developed for GEO 600, the German/UK interferometric gravitational wave detector, currently being commissioned. In that detector all the low frequency resonant modes of the triple pendulums are damped by control systems using collocated sensing and feedback at the highest mass of each pendulum, so that significant attenuation of noise associated with this so-called local control is achieved at the test masses. To achieve the more stringent noise levels planned for Advanced LIGO, the GEO 600 local control design needs some modification. Here we address one particular approach, namely that of using eddy-current damping as a replacement or supplement to active damping for some or all of the modes of the pendulums. We show that eddy-current damping is indeed a practical alternative to the development of very low noise sensors for active damping of triple pendulums, and may also have application to the heavier quadruple pendulums at a reduced level of damping.


Item Type:Article
Additional Information:©2004 American Institute of Physics (Received 27 May 2004; accepted 25 July 2004; published online 29 October 2004) The authors would like to thank Bill Edelstein, David Shoemaker, and Jim Faller for their helpful advice and interest in this work. The authors acknowledge the financial support of the University of Glasgow and the PPARC. N.A. Robertson was supported by the National Science Foundation under NSF Grant PHY-0140297. C.I. Torrie, M. Barton, P.A. Willems, and J.H. Romie were supported by the National Science Foundation under NSF Grant No. PHY-0107417.
Subject Keywords:gravitational wave detectors; damping; light interferometry; pendulums; eddy currents; transfer functions; thermal noise
Record Number:CaltechAUTHORS:PLIrsi04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:PLIrsi04
Alternative URL:http://dx.doi.org/10.1063/1.1795192
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5029
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:22 Sep 2006
Last Modified:26 Dec 2012 09:03

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