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Virgo+ Commissioning Status

Virgo+ Commissioning Status. Main upgrades and activities. Laser system: from 10  25 watt output power at the IMC TCS: ring + Central Heating Electronics: ADCs and DSP replacement, Global Control Viewports replacement NE mirror replacement CB electrical net and Grounding

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Virgo+ Commissioning Status

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  1. Virgo+ Commissioning Status

  2. Main upgrades and activities • Laser system: from 10  25 watt output power at the IMC • TCS: ring + Central Heating • Electronics: ADCs and DSP replacement, Global Control • Viewports replacement • NE mirror replacement • CB electrical net and Grounding • Infrastructure works to noise reduction (EE room)

  3. “Affected” Viewports From inside Broken viewport • The windows are: • standard viewports off the catalogue • supplied by Varian, Italy, in 2002 • built by Instrument Technology Limited, UK • glass 7056, with a thickness of 6.2 mm, with a view diameter of 137 mm, mounted on 8.0” CF-F flanges • designed to withstand a bake out Damaged viewport From outside STAC Meeting, Nov08 3

  4. Damages • The mirror has been scratched by the spray of glass fragments projected by the broken viewport • The reference mass has been damaged with grows and glass fragments fused in the Aluminum surface Other components in the NE tower have been damaged: STAC Meeting, Nov08 4

  5. Viewports replacement • In Virgo the total number of viewports to be finally changed is 91 = 41 He-coated + 48 uncoated + 2 YAG coated • Taking into account delivery + installation time complete substitution  15 December • Some are “historical viewports” for visual inspection, others will be no needed before some months (photon calibration) • Mounting only the really needed viewports for correct ITF working the number is reduced to 55 – these viewports have been progressively mounted (tower by tower) leaving at least two reference positions to maintain the beam aligned. • Viewports no more in the critical path in 15 October

  6. Central Building Electrical net (old) • In the years the electrical net has grownby “additions” • in the scheme red lines are UPS lines – blue lines are ENEL (Italian Electrical distributor) lines

  7. Central Building electrical net (new) • Shut down during this week to complete replacement

  8. Grounding • The ground net has been reviewed, rationalized, mostly re-cabled • Work ends during this week shut down

  9. Environmental noises Noise from EIB (May 6th) • Good modeling of the coupling of diffused light to DF => Non negligible contribution 40 Hz • Improvements planned: - Optics: Continue ‘cleaning’ Better beam dumps NE transmission /4 - Reduce the motion of benches:  Improve benches mechanics  Resonance dampers  Electronics racks removed from Laser Laser in the new EEroom - Improve AC: shutdown work in central building

  10. Works of CE hall HVAC Thanks to P.Popolizio, D.Soldani and the EGO infrastructure group. • The machine is designed to provide an high air flux (42.000 m^3/h). This is to high for normal operations. So the flux had been brought to need (23.000 m^3/h) by partially closing (70%) an intermediate air grid. This was a cause of increased air turbulence and noise (see Elog #20278). • Between Sept. 29 and Oct 4 we reduced the fans speed (by -25%) by replaceing the engines (48 poles: half rmp, half power) and changing pulleys • We tested 4 sets of pulleys (fan speed from 118 Hz). Left running with set n.4. • We also fully opened the intermediate air grid, and kept it opened.

  11. Injection: Modifications of LB and EIB for Virgo+ Goal : Increase the laser power up to 50 W (at the output of the laser bench).

  12. The Laser & injection system layout for Virgo+ http://wwwcascina.virgo.infn.it/optics/layouts/VirgoLayout/VirgoPlus_01_2.pdf

  13. Virgo+ new laser and ISYS most relevant steps • Pre Mode-Cleaner cavity integration (june) • Seed power = 19W  Power incident on PMC = 60.3W  TPMC=87.7%  PoutPMC = 52.9 W. • New IMC end mirror has been installed • The commissioning of ISYS loops has started (BMS, IB AA and MC AA up to maximum power (27 W transmitted by the IMC)). • IMC and SIB faraday isolator thermal effects checks. • SIB Faraday isolation improvement by adding an halfwave plate between the first polarizer and the Magneto-optic crystal.  ISYS commissioning completed by the end of october.

  14. Evidences of thermal effects in the IMC cavity • We measured RFC contrast defect at different powers  Thermal lensing in the faraday is present but we have also some thermal lensing in the IMC cavity since with the same amount of power travelling through the faraday, RFC contrast defect is worse when there is more power inside the IMC cavity. PR mirror

  15. Lock acquisition sequence is working again up to final state (step 12) Full control architecture has been tested Different thermal behavior of the interferometer More robust than before Allowed a reduction of acquisition time from 25 to 15 minutes Sensitivity: noise hunting not yet started Not yet accurately calibrated High frequency: oscillator phase noise Mid frequency: frequency noise (servo not yet re-tuned) Low frequency: longitudinal control noise (servos not yet re-tuned) Commissioning status

  16. Simulation Mirror properties • Ellipticity of CO2 beam • Centering accuracy • Radius annulus • Thickness annulus • Central Heating Spot size Temperature distribution in the mirror (function of time) Step1 TCS Optical Bench Setup - Central heating issue- Optical setup dof - axicon defects / aberrations CO2 beam shape • Ansys (A. Rocchi) • Matlab code (R. Day) • Matlab code (B. Swinkels) • Analytical analysis (J-Y. Vinet) • Zemax (A. Rocchi, R. Day, E. Genin, P. La Penna) Step2 Step3 • Interferometer setup • LMA Phase maps transmission • LMA Phase maps reflection • - single cavity • double cavity • ITF • locking signals behaviour • SB recycling gains • phase camera images • Phase maps • Excess optical path • Coupling losses • Thermo-optic effect • Thermo-elastic effect • Elasto-optic effect • Depolarisation effect • DarkF (M. Pichot, R. Day) • Finesse (E. Calloni, M. Parisi, J. Marque) • Ansys (A. Rocchi) • Matlab code (R. Day) • Matlab code (B. Swinkels) • Analytical analysis (J-Y. Vinet)

  17. YAG/CO2 - Temperature distribution, Excess optical path (Analytical, Matlab) Excess optical path computed also for the CO2 beam

  18. Coupling loss, recycling gains evolution (DarkF, Matlab) TCS “switched on” when lock is acquired Coupling losses (comparison between distorted wavefront and the undistorted one) and recycling gains are good figures of merit for the thermal compensation correction. Central heating spot is required not to undergo hours of thermal transitions.

  19. TCS • Use of the central heating • Install first the TCS with only the ring heating

  20. Virgo ADC Pr RIO Pr_Gc - Fb RTPC DAQ\RIO Gc RIO – C36 Sc DSP Virgo DAC DAQ Electronic upgrades • New control electronics: • Functional tests of whole chain (ADC, Gc software, timing) • Put in use and validate ADCs for monitoring channels • Install a DSP in the WI tower and test - Inertial Damping • The rest of electronics : ADCs for angular and longitudinal controls, new DSP on all towers, will be installed and commissioned progressively Signals sent via the new Optical link (TOLM) - Test of Frame Builder and Global control on Real Time PC Control DOL link DAQ DOL link TOLM link

  21. Main steps toward VSR2 • First Virgo+ Locking (8 watt) 2) Aberrations free interferometer (1 8 watt) 3) High sensitivity @full power

  22. 1 – Reasonable hot ITF sensitivity • Retuning of demodulation phases for locking up to step 8. Retuning of locking and alignment phases and gains. (2 weeks) • Reaching step 8 (1 week) • Output Mode cleaner recovering – step 9 (1/2 week) • Low noise locking filter retuning –step 10 (1/2 week) • Force reallocation on the marionette and low noise on suspensions – step 11 - (1/2 week) • Retuning of noise control suppressions (a,b,g) – step 12 – (1/2 week) • Noise hunting towards a reasonable sensitivity – (3 weeks) Total time to reach status 1  8 weeks. Notice: in this scheme it is assumed that the GC used is still the old one, as well as control and sensing ADCs.

  23. 2 – Aberrations free interferometer (ref. sol) • TCS commissioning and standard configuration. The goal is to reach a status of the interferometer defined as the working at 8 watt power and with fast lock recovering. This configuration is called standard. Tests up to 25 watts • 2.1) Characterization of cold interferometer. The input power is 1 watt. The goal is to define the working point of the ITF, measure the sidebands aberrations in cold state, compare with simulations. • 2.1.1) Locking Phases and gains retuning to reach step 8 – 1 week – • 2.1.2) Sidebands aberrations measurements. Maps of working point – 1/2 week • 2.1.3) Optical characterization and ITF working point definition – 1/2 week • 2.1.4) TCS Transfer function measurement and characterization – 1 week • 2.2) Power rising to 8 watts maintaining the ITF controlling aberrations. Implementation of central spot for fast lock recovering  standard configuration • 2.2.1) Input power rise to 2 watt. Thermal effect measurement and TCS control with annular and central spot – 1 week • 2.2.2) Power to 4 watts. Thermal effects and fast recovering - 1/2 week • 2.2.3) Power to 8 watt. Thermal effects control. – 1/2 week • 2.2.4) Thermal effect control at 8 watts. Tests at 16 watts – 1 week • 2.2.5) Power to 8 watt - Fast recovering procedure identification. 25 watts tests – noise hunting - 1 week • 2.2.6) Standard configuration definition. 25 watts tests- noise hunting - 1 week - Total time to reach status 2, the standard configuration  8 weeks.

  24. Amplitude Y Carrier Phase Sidebands Aberrations free ITF (alter. Sol) 1-2 days problem of macthing when rising input power TCS characterization • Phase camera 1 will provide a fundamental tool to calibrate TCS effect Use phase camera to measure “distorted” phase of sidebands using “cleaned” carrier from FP cavity as reference Use single Fabry-Perot cavity This way we measure distortion of each input mirror separately Input mirror deforms traversing wavefronts One of two cavities misaligned PR misaligned RF demodulated (R. Day) DC Phase camera X

  25. 3 – High sensitivity @ full power • Low noise full power. Science Mode definition.The activities will be devoted to obtain a 25 watt input power configuration in ITF working point as defined by standard configuration. • 3.1) 25 watt - annular thermal effects control. Noise hunting – 2 weeks • 3.2) Fast lock recovering. Noise hunting - 2 weeks • 3.3) Noise hunting and SM definition– 6 weeks • Total time to reach status 3, ITF in SM  10 weeks.

  26. Hardware upgrades Hardware to be upgraded: • Phase camera (Phase 1) • New coil drivers (during phase 2) • Installation of ADCs for detection and control (during phase 2) • New DSPs (phase 1 & phase 2) • Photodiodes under vacuum (to be decided) • AC noise mitigation (CB machine isolation TBD) • Cryotrap reservoir Total time: 6 weeks of non-parallel works (exclusive ITF use)

  27. Conclusion • Commissioning has restarted • The highest uncertainties on date for VSR2 comes for periods of noise hunting. • VSR2 should start at the end of June.

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