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Type-A SAS Local Control Simulation (Current Status)

JGW-G1402200-v1. Type-A SAS Local Control Simulation (Current Status). T. Sekiguchi. 2014/01/22. Local Control Strategy. (based on Virgo control scheme). During interferometer operation: Resonances of pendulum modes are damped by IP control to reduce RMS.

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Type-A SAS Local Control Simulation (Current Status)

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  1. JGW-G1402200-v1 Type-A SASLocal Control Simulation(Current Status) T. Sekiguchi 2014/01/22

  2. Local Control Strategy (based on Virgo control scheme) During interferometer operation: • Resonances of pendulum modes are damped by IP control to reduce RMS. • No longitudinal damping is applied at IM. • Pitch & yaw of TM are controlled by optical levers. For lock acquisition: • Resonances of internal modes are damped by using local sensors (OSEMs) at IM.

  3. IP Control • We have not yet achieved required TM RMS displacement (= 1e-7 m). • Two disturbing points: • Notch at 0.16 Hz in actuator response of IP • Glowing sensor noise of geophone at low frequencies http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/DocDB/ShowDocument?docid=2132

  4. IP Control • Open loop gain Notch at 0.16 Hz

  5. IP Control • Sensor Blending

  6. Optical Lever Control • Optical lever control is applied to reduce RMS of mirror pitch & yaw: Preliminary

  7. OpLev Sensor Noise Contribution • Assuming optical lever sensing noise of 3e-11 rad/rtHz (at 10 Hz).(estimated from analogue electronics noise used in i-KAGRA) • Pitch and yaw: OK, but noise coupling to Z is large. • Large coupling from pitch actuation to zTM: can it be mitigated by actuator diagonalization?? 10 times larger than requirement

  8. OpLevSensor Noise Contribution • Pitch OK

  9. OpLevSensor Noise Contribution • Yaw OK

  10. Local Damping with OSEM • Check damping time of resonances (Z and Pitch) GAS Filter Tilt Mode

  11. Displacement Noise During Damping • Assuming OSEM sensitivity of 2e-10 m/rtHz @10 Hz (measured in prototype at room temperature)

  12. Future Works TBD • Requirement for inertial sensor noise • Requirement for local sensor noise at IM (used for damping) • Requirement for actuator noise • Simulation about other DoFs (transversal, vertical, roll, yaw)

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