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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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Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

Scopo di LISA PAthfinder

Sensitivityof LISA

Laser link

Laser link

  • Soppressionedelleaccelerazioniparassite a megliodi 3×10-14 ms-2√Hz

  • (10 volte menostringentedi LISA)


Lisa pathfinder preventivi 2013 gruppo di trento

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)


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

  • 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


Lisa pathfinder preventivi 2013 gruppo di trento

GRS on groundtestingwithtorsionpendulum


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

  • 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


Lisa pathfinder preventivi 2013 gruppo di trento

  • 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


Lisa pathfinder preventivi 2013 gruppo di trento

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.


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

Composizione LISA PF Trento

Richieste 2013 (preliminare)

Nessuna richiesta ai Servizi


Extra

extra


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

Brownian noise

LPF FM-replica

Same FM TM finishing

The GRS contributionisobtainedasdifferencebetweenthisvalue and the simulatedonefor 4TM pendulumwithout GRS

Simulationwithout GRS


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

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


Lisa pathfinder preventivi 2013 gruppo di trento

  • 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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