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LISA Pathfinder Preventivi 2013 Gruppo di Trento

LISA Pathfinder Preventivi 2013 Gruppo di Trento. Principal investigator della missione LISA Pathfinder Testing a terra del sensore gravitazionale con pendoli di torsione Testing a terra della fase di rilascio in volo della test mass. Scopo di LISA PAthfinder. Sensitivity of LISA.

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LISA Pathfinder Preventivi 2013 Gruppo di Trento

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  1. LISA PathfinderPreventivi2013 Gruppodi Trento Principalinvestigator della missione LISA Pathfinder Testing a terra del sensore gravitazionale con pendoli di torsione Testing a terra della fase di rilascio in volo della test mass

  2. Scopo di LISA PAthfinder Sensitivityof LISA Laser link Laser link • Soppressionedelleaccelerazioniparassite a megliodi 3×10-14 ms-2√Hz • (10 volte menostringentedi LISA)

  3. LISA PF a Trento LISA PF in Europa France: Laser modulator Germany: Co - PI, LTP Architect (Astrium), Laser Italy: PI, Inertial Sensor (ISS), Caging Mechanism Netherlands: ISS SCOE Spain: Data Diagnostics System, Data Management Unit Switzerland: ISS Front End Electronics United Kingdom: Optical Bench, Phase-meter, Charge Management LISA PF in Italia Collaborazione INFN LISA PF AQ, FI, NA,RM2 eTN: circa 30 persone (19 FTE)

  4. ATTIVITA’ DEL GRUPPO di TRENTO Principalinvestigator della missione LISA Pathfinder • ----- Il monitoraggio dello sviluppo del programma e delle prestazioni • -----Attività di “shadowengineering” : • supporto all’indagine/soluzione delle non-conformances riportate sull’hardware consegnato • ------ Supporto alla missione: • sostegno alla MissionCritical Design Review, supporto all’analisi degli aspetti critici della missione • ------ Sviluppo dell’esperimento in orbita e dell’analisi dati • ------Sviluppo dei tool di analisi dati: nel 2012 Release 3.0 del software di analisi dati LTPDA • ------ Preparazione delle operazioni di LISA PF Testing a terra del sensore gravitazionale con pendoli di torsione Testing a terra della fase di rilascio in volo della test mass

  5. Stato di avanzamento di LISA Pathfinder • LTP status: allpartsdelivered and workingtospecsexceptsfor: • - EH repairingactivityunderway (guardringdetachmentduringvibration test) • - Charge management sistemunderperforming: fix under finalisation • TM launchlock: foundtechnicallyfeasiblesolutions; CDR isunderway. Science Module: H/W complete - except -LTP Coreassembly -Micro-propulsion system: identified more that one viable alternatives, including a cold-gas based one with off-the-shelf maturity that is now the likely adopted baseline. Final decision in 2012. • In 2011 a quite important test of all the optical metrology integrated into the complete spacecraft (except for the inertial sensor) and within a full space simulator, has been performed. The test has been a success. LANCIO NEL 2014

  6. GRS on groundtestingwithtorsionpendulum

  7. GRS prototypes and LPF-like Test Masses : increasing representativeness NOW ! GRS 4 mm gaps, LPF geometry Mo / Shapal EM LPF FM-replica Mo / Sapphire LPF EM LPF-like TM nmroughness ! Lightweight : empty TM in goldcoated Al Same FM TM finishing

  8. GRS on groundtestingwithtorsionpendulums Results 2011-2012 • GRS Flight Model Replica and 4 mass pendulum: • Studyof UV discharge performance afterbakeout at 110° C completed , demonstratingmarginal performance (stillallows “useasis” in flight) • Testsofdcstrayelectrostaticbias, temperature gradienteffects (radiometer, radiationpressure, temperature dependetoutgassing), and Browniannoisecompleted: alleffects are withinrequirements • GRS prototype and 1 mass pendulum (high sensitivitypendulum): • Experimentalinvestigationof TM chargeinteractionwithstrayelectrostaticfields inside GRS • with upper limitsbelowfor the surfacepotentialfluctuations 12 mV/Hz1/2 between 5 cm2 patches on a Au surface at 1 mHz • Refinedtechniquefordirectlymeasuringstray DC fieldcouplingto TM charge in flight on LPF / LISA • [PRL 108, 181101 (2012)] • Measurementofelectrostaticdissipation in nominally-vacuum gap capacitors inside GRS •  detection oftransientforcesassociatedwithdissipation at 10-17 Nmlevel • meausuementof loss angle d ≈ 3 10-7 for 2 electrodepairs, consistentwithfrequencyindependent loss model • sufficientlysmallfor LISA • Developmentofnrad-interferometricangularreadoutfortorsionpendulum • Bench top preliminary (in air) measurementswithinfactor 10 of goal • Vacuumtesting and pendulumintegrationupcoming

  9. GRS on groundtestingwithtorsionpendulums • Activity 2012-2013 • Torsionpendulumupgrades: integrationofnew (1 TM) torsionpendulumwithinterferometricangularreadout • (willallowformeasurementofforcenoisefrom GRS at levelsbeyond LPF goal and Improvedmeasurementofstraypotentialfluctuations) • Completionof test campaignwithcurrent-baselineflight-model GRS Flight model replica + flight-representative TM (upper limitof the overallforcedisturbanceform the GRS) • Integration in the 4 TM pendulumof a new TM withAuPtinserts+ GRS with the samecleaning procedure of the FilghtModel ( particularlyrelevantfor the UV discharge procedure performances) • Supportfordefinition / testingof LPF flight measurementsequence (including free fall mode) • and associated data analysisproceduresusing LTPDA toolbox

  10. On ground Test Mass releasetesting • Attività gennaio-giugno 2012 • Misura del trasferimento di quantità di moto utilizzando l’attuatore attualmente a disposizione (PILine)con i mock-up intermedio (100g) e pesante (1kg) di test mass. • Elaborazione dei dati sperimentali raccolti al fine di ricavare la legge forza-elongazione del legame adesivo • Lavorazione di inserti Au/Pt con morfologia superficiale rappresentativa del recesso piramidale della test mass di volo per successive prove di trasferimento di quantità di moto in assenza di coating d’oro o in presenza di coating antiadesivo • Attività previste 2012-2013 • Misura del trasferimento di quantità di moto utilizzando l’attuatore attualmente a disposizione (PILine)con il mock-up pesante (1kg) di test mass impiegando inserti Au/Pt privi di coating d’oro o dotati di coating antiadesivo • Misura del trasferimento di quantità di moto installando il GPRM nella facility.

  11. The Test Mass release testing • The Grabbing Positioning and Release Mechanism (GPRM) is designed to hold and release the TM into free fall. • The release is performed by quick retraction of two tips. • The TM may be captured by the capacitive actuation system if its residual velocity after release is less than 5 micron/s (10-5 Ns impulse). • Gold coated surfaces (tip/TM) develop strong adhesive bonds. • Adhesion between the tips and the TM produces a pull (a momentum transfer) during release. • The verification of the requirement of residual velocity is part of the LISA PF ground testing activities. • The Transferred Momentum Measurement Facility is developed to characterize the TM release velocity

  12. Composizione LISA PF Trento Richieste 2013 (preliminare) Nessuna richiesta ai Servizi

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  14. Thermalgradientrelatedforces: LPF GRS replica afterbake-out at 110 C Radiation pressure Tempdependent outgassing Radiometer Slope affected by the accuracy of the Ion P gauge, which is nominally 15% Closeto the expected @293 K @ P=2e-8 mbar Radiometer 23 pN/K  5 pN/K T dependentOutgassingprobablydominates

  15. Brownian noise LPF FM-replica Same FM TM finishing The GRS contributionisobtainedasdifferencebetweenthisvalue and the simulatedonefor 4TM pendulumwithout GRS Simulationwithout GRS

  16. Random TM chargingandDCstraypotential: LISA Pathfinder GRS replica Compensazione dcbias -Vcomp -Vcomp +Veq +Veq -Veq -Veq +Veq-Vcomp=0 +Veq-Vcomp=0 -Veq+Vcomp=0 +Vcomp -Veq+Vcomp=0 +Vcomp Force Force Force Force Force Force Force +Veq-Vcomp=0 +Veq-Vcomp=0 -Vcomp -Vcomp +Veq +Veq -Veq+Vcomp=0 -Veq+Vcomp=0 +Vcomp +Vcomp -Veq -Veq compensationto <1 mVdemonstrated Error due toshearforcecompensationnotpresentwith TM charge, orderof 10 mV controlwithreal TM chargevariation

  17. Interactionofstrayelectrostaticfields and TM charge • Upper limits on surfacepotentialfluctuations • < 12 mV/Hz1/2 at 1 mHz on 5 cm2 Au surfaces • < 2 fm/s2/Hz1/2for LISA /LPF TM • Directmeasurementofstray DC fieldcouplingtonoisy TM charge • refinesin-flighttechniquetonullingsurfacepotentialdifferencesto < 1 mV

  18. Experimentalinvestigationofelectrostaticdissipation Thermodynamicforcenoise source for LISA and experimentalgravitation Stochasticsurfacepotentialfluctuationsfromsurfacedissipationmixeswithstaticpotentialdifferencestogiveforcenoise vn dV • Squarewavemodulationtechnique, 10-17Nmtransienttorqueresolution • Detect loss angle d≈ 3 10-7for 2 electrodepairs smallenoughfor LISA! • Waveform and distancedependenceconsistentwithdindependentoffrequency

  19. Angularinterferometer: nrad/Hz1/2 sensingforsub-fNforce detection Bench-topdevelopment • Status: • Workingheterodynemodulationbench, homemadephasemeter, and single bounceMach-Zehnder IFO • In vacuumrotationalnoise test summer 2012, torsionpendulumintegrationFall-Winter 2012-2013 2 1 Preliminaryin-airnoisemeasurements 3 4 “Rotation cancelling” phasecombination

  20. Test performed exploring different directions of retraction searching the maximum impulse • With 100g TM dummy the max measured impulse is 3.5×10-5N*s (3.5 times the requirement) • Possible margin hidden by the “slow” tip retraction performed in the experiment wrt the GPRM Grabbing Positioning and Release Mechanism (GPRM) Impulse (N*s) vs. tiporientation Impulse (N*s) vs. tiporientation • Extrapolation to in-flight release made with the identified mathematical model of the mechanism shows compliance with the requirement (2.6 margin factor) • Due to the criticality of the release, the testing of the GPRM EQM in the TMMF is foreseen for improved representativeness

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