LIGO Document T970191-x0

Test Mass Transmissibility

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Document type:
T - Technical notes
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16 Jul 2010, 08:37
Although the internal resonances of the test mass are beyond the Length Sensing and Control (LSC) control bandwidth, any (unintended) magnetic coil drive currents at the test mass resonances will be amplified by the high Q of the test mass. The transmissibility of applied force at the magnet positions to displacement response of the front surface of the LIGO test mass is calculated via finite element analysis. Based upon the transmissibility, the gain attenuation required in the length control system, in order to prevent driving the test mass motion at resonance beyond acceptable limits, may be established.
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Notes and Changes:

Rev T970191-03-D:
- Full document number: LIGO-T970191-03-D
- Author(s): Dennis Coyne
- Document date: 1998-02-10
- Document received date: 1998-03-23
- Document entry date: 1998-03-23

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