Nov ’01, page 1 Current Work on Hydraulics for LIGO 1 and Advanced LIGO Rich Abbott, Graham Allen, Daniel DeBra, Joe Giaime, Giles Hammond, Marcel Hammond, Corwin Hardham, Jonathan How, Wensheng Hua, Brian Lantz, Ken Mason, Rich Mittleman, Jamie Nichol, Joshua Phinney, Gerry Stapfer JILA, LLO, LSU, MIT, Stanford

Nov ’01, page 2 Functional Description of the System ~10 -6 m rms above 0.1Hz ~10 -8 m rms above 1Hz, ~ m/√Hz at 10 Hz ~10 -7 m rms (0.1Hz), ~10 -8 m rms (1Hz), ~ m/√Hz m rms differential, m/√Hz (10 Hz) ~10 -7 m rms (0.1Hz), ~ m rms (1Hz), m/√Hz (10 Hz)

Nov ’01, page 3 View of the LIGO vacuum tanks HAM BSC

Nov ’01, page 4 Motivation for an External Stage Isolation –From the micro-seismic peak to 10 Hz Alignment –Seasonal Temperature Changes Control Reallocation –Reduce control effort / noise from inner stages High Impedance Support –Inner stages react against stiff, damped foundation

Nov ’01, page 5 Performance Requirements Range of Motion –Mechanical Adjustment: 5 mm. –Active Control: +/- 1 mm. Response –Initial Response: 1 mm. in 10 sec. –Bandwidth: Hz. Resolution and Noise –Reduce the ground motion by 10 from 0.1 to 3 Hz

Nov ’01, page 6 Differential Bellows for Quiet Actuator 1) Pump 2) Differential Flapper Valve 3) Bellows Supply 4) Differential Bellows 5) Actuation Plate

Nov ’01, page 7 The Quiet Hydraulic Actuator Current Design Current Design Implemented On LIGO Pier Bellows Actuation Plate Servo Valve Displacement Sensor

Nov ’01, page 8 Conditioning a Pressure Source Servo Valve Compensator Pressure Sensor Pump Reservoir Accumulator Active and Passive Suppression of Pressure Fluctuations

Nov ’01, page 9 Pressure Noise at the Actuator

Nov ’01, page 10 The Test Platform at Stanford Vertical Actuator Displacement Sensor Seismometer (Geotech S-13) Seismometer (Streckeisen STS-2) 800 lb Test Mass Horizontal Actuator Vertical Actuator

Nov ’01, page 11 Sensor Correction zgzg z m - z g STS2 Filter Compensator + External Alignment Input +

Nov ’01, page 12 Vertical Isolation

Nov ’01, page 13 Horizontal Isolation

Nov ’01, page 14 New Pumping Stand Build new system with improved low freq range, and capacity to drive 8 actuators. Allow Stanford and LASTI to order identical stations (easier debugging). Reservoir Motor and pump Granite block (isolation)

Nov ’01, page 15 New Pump Station is Progressing Motor Pump Motor controller Bypass valve Pressure sensor Accumulator Filter

Nov ’01, page 16 Candidate Actuators Hydraulic Force Velocity Displacement Stiction Mechanical Noise Hysteresis Stiffness HighMed High LowMedLow High Low High Low HighLow High Low High Piezo or Magnetostriction Linear Motor Ball Screw High

Nov ’01, page 17 Equations of Motion Valve Volumes Flow Mass