Post on 02-May-2015
transcript
1
LISA PathfinderPreventivi 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
Padova, 09/07/2012
2
Scopo di LISA PAthfinder
Laser
link
Laser link
Soppressione delle accelerazioni parassite a meglio di 3×10-14 ms-2√Hz
(10 volte meno stringente di LISA)
Sensitivity of LISA
Padova, 09/07/2012
3
LISA PF a TrentoRICERCATORIDolesi Rita associato Ricercatore 90Giuliana Russano associato Dottoranda 100Vitale Stefano associato Prof. Ordinario 80Weber William associato Ricercatore 90Antonucci Federica associato Assegnista 100Tu Hai Bo associato Assegnista 100Congedo Giuseppe da associare Assegnista 100Ferroni Valerio da associare Assegnista 100Wen Shyang da associare Assegnista 100Cavalleri Antonella da associare Ricercatore (CNR FBK) 90
Tot RICERCATORI (FTE) 9,5
Hueller Mauro Non associabile Co Co Co 50
TECNOLOGIBenedetti Matteo associato Ricercatore 40Bortoluzzi Daniele associato Prof. Associato 70Bosetti Paolo associato Ricercatore 10Cristofolini Ilaria associato Ricercatore 10De Cecco Mariolino associato Prof. Associato 10Da Lio Mauro associato Prof. Ordinario 10Mezzena Renato associato Tecnologo E.P. 10
Tot TECNOLOGI (FTE) 1,6Tot TECNOLOGI (FTE) >10% 1,1
France:Laser modulator Germany: Co - PI, LTP Architect (Astrium), LaserItaly: PI, Inertial Sensor (ISS), Caging MechanismNetherlands: ISS SCOESpain: Data Diagnostics System, Data Management UnitSwitzerland:ISS Front End ElectronicsUnited Kingdom: Optical Bench, Phase-meter, Charge Management
LISA PF in ItaliaCollaborazione INFN LISA PFAQ, FI, NA,RM2 eTN: circa 30 persone (19 FTE)
LISA PF in Europa
Padova, 09/07/2012
4
ATTIVITA’ DEL 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
----- Il monitoraggio dello sviluppo del programma e delle prestazioni
----- Attività di “shadow engineering” : • supporto all’indagine/soluzione delle non-conformances riportate
sull’hardware consegnato
------ Supporto alla missione: • sostegno alla Mission Critical 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
Padova, 09/07/2012
5
Stato di avanzamento di LISA Pathfinder
LTP status: all parts delivered and working to specs excepts for:- EH repairing activity underway (guardring detachment during vibration test)- Charge management sistem underperforming: fix under finalisation-TM launch lock: found technically feasible solutions; CDR is underway.
-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.
Padova, 09/07/2012
LANCIO NEL 2014
Science Module: H/W complete - except -LTP Core assembly -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.
6
GRS on ground testing with torsion pendulum
TM
Autocollim ator beam
X sensing electrodes
shaft
fiber
Padova, 09/07/2012
7
Mo / Shapal EM Mo / Sapphire LPF EM
GRS prototypes and LPF-like Test Masses :
increasing representativeness
Padova, 09/07/2012
Lightweight : empty TM in gold coated Al
GRS4 mm gaps,
LPF geometry
LPF-like TM
nm roughness !
LPF FM-replica
Same FM TM finishing
NOW !
8
GRS on ground testing with torsion pendulums
Results 2011-2012
GRS Flight Model Replica and 4 mass pendulum:
• Study of UV discharge performance after bakeout at 110° C completed , demonstrating marginal performance (still allows “use as is” in flight)
• Tests of dc stray electrostatic bias, temperature gradient effects (radiometer, radiation pressure, temperature dependet outgassing), and Brownian noise completed: all effects are within requirements
GRS prototype and 1 mass pendulum (high sensitivity pendulum ):
• Experimental investigation of TM charge interaction with stray electrostatic fields inside GRS with upper limits below for the surface potential fluctuations 12 mV/Hz1/2 between 5 cm2 patches on a Au surface at 1 mHz Refined technique for directly measuring stray DC field coupling to TM charge in flight on LPF / LISA[PRL 108, 181101 (2012)]
• Measurement of electrostatic dissipation in nominally-vacuum gap capacitors inside GRS detection of transient forces associated with dissipation at 10-17 Nm level meausuement of loss angle d ≈ 3 10-7 for 2 electrode pairs, consistent with frequency independent loss model sufficiently small for LISA
• Development of nrad-interferometric angular readout for torsion pendulum Bench top preliminary (in air) measurements within factor 10 of goal Vacuum testing and pendulum integration upcoming
Padova, 09/07/2012
9
GRS on ground testing with torsion pendulums
Activity 2012-2013
Torsion pendulum upgrades: integration of new (1 TM) torsion pendulum with interferometric angular readout(will allow for measurement of force noise from GRS at levels beyond LPF goal and Improved measurement of stray potential fluctuations)
• Completion of test campaign with current-baseline flight-model GRS Flight model replica + flight-representative TM (upper limit of the overall force disturbance form the GRS)
• Integration in the 4 TM pendulum of a new TM with AuPt inserts+ GRS with the same cleaning procedure of the Filght Model ( particularly relevant for the UV discharge procedure performances)
• Support for definition / testing of LPF flight measurement sequence (including free fall mode) and associated data analysis procedures using LTPDA toolbox
Padova, 09/07/2012
10
On ground Test Mass release testing
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.
Padova, 09/07/2012
11
The Test Mass release testing
Padova, 09/07/2012
• 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
Richieste 2013 (preliminare)Nessuna richiesta ai Servizi
RICERCATORI
Dolesi Rita Ricercatore 90
Giuliana Russano Dottoranda 100
Vitale Stefano Prof. Ordinario 80
Weber William Ricercatore 90
Antonucci Federica Assegnista 100
Tu Hai Bo Assegnista 100
Congedo Giuseppe Assegnista 100Ferroni Valerio Assegnista 100
Wen Shyang Assegnista 100Cavalleri Antonella Ricercatore (CNR FBK) 90
Tot RICERCATORI (FTE) 9,5
Hueller Mauro Co Co Co 50
Composizione LISA PF Trento
Missioni 8000Consumo Ricerca 9000Manutenzione 6000
I nventariabile (pompa turbo 400 l/s, lettore di pressione calibrato, RGA, 4 controller per motor, posizionatore lineare piezoelettrico) 33000Costruzione apparati (specchi per interferometro e per pendoli, refurbishment GRS Replica) 30000Totale Richieste 2013 86000
Cavalleri Antonella
TECNOLOGI
Benedetti Matteo Ricercatore 40
Bortoluzzi Daniele Prof. Associato 70
Bosetti Paolo Ricercatore 10
Cristofolini Ilaria Ricercatore 10
De Cecco Mariolino Prof. Associato 10
Da Lio Mauro Prof. Ordinario 10
Mezzena Renato Tecnologo E.P. 10
Tot TECNOLOGI (FTE) 1,6Tot TECNOLOGI (FTE) >10% 1,1
Padova, 09/07/2012
13Padova, 09/07/2012
EXTRA
14
Thermal gradient related forces:
2
04
0
3
0
05
20
03
00
293
1034.1
)(40
29327
293
1018
)(3
8
4)(
T
K
KsnJTQ
K
pN
K
Tk
K
pN
T
K
Pa
Pk
K
pN
TTAQT
ck
T
PAk
Td
dF
rpR
rpRx
x Radiometer
Radiationpressure
Temp dependentoutgassing
LPF GRS replica after bake-out at 110 C
0 0.5 1 1.5 2 2.5
x 10-6
0
1
2
3
4
5
6
7x 10
-10
dF
orc
e/d
T (
N/K
)
Pressure (mbar)
Slope affected by the accuracy of the Ion P gauge, which is nominally 15%
T(K) Slope (N/K/mbar)
stat. error(N/K/mbar)
Intercept(pN/K)
stat. error(pN/K)
289.20 2.47e-4 2e-6 26 3295.46 2.39e-4 3e-6 36 1304.30 2.75e-4 4e-6 53 4
Close to the expected @293 K
@ P=2e-8 mbar
Radiometer 23 pN/K 5 pN/KT dependent Outgassing probably dominates
Padova, 09/07/2012
15
Brownian noise
LPF FM-replica
Same FM TM finishing
The GRS contribution is obtained as difference between this value and the
simulated one for 4TM pendulum without GRS
Simulation without GRS
Padova, 09/07/2012
16
Compensazione dc bias
Random TM charging andDC stray potential: LISA Pathfinder GRS replica
mHz 1 /s1000mV 10
fN/Hz 2.02 2/1
1/22
2/1 f
x
C
C
eS EFFx
xT
EFFF
ForceForceForceForce
+Veq
+Veq
-Veq
-Veq
Force
+Veq
+Veq
-Veq
-Veq
+Veq-Vcomp=0
+Veq-Vcomp=0
-Veq+Vcomp=0
-Veq+Vcomp=0
+Veq-Vcomp=0
+Veq-Vcomp=0
-Veq+Vcomp=0
-Veq+Vcomp=0
-Vcomp
-Vcomp
+Vcomp
+Vcomp
ForceForce
-Vcomp
-Vcomp
+Vcomp
+Vcomp
compensation to <1 mV demonstratedError due to shear force compensation not present with TM charge,
order of 10 mV control with real TM charge variation Padova, 09/07/2012
17
Interaction of stray electrostatic fields and TM charge
Upper limits on surface potential fluctuations• < 12 mV/Hz1/2 at 1 mHz on 5 cm2 Au surfaces• < 2 fm/s2/Hz1/2 for LISA /LPF TM
Direct measurement of stray DC field coupling to noisy TM charge• refines in-flight technique to nulling surface potential differences to < 1 mV
Padova, 09/07/2012
18
Experimental investigation of electrostatic dissipationThermodynamic force noise source for LISA and experimental gravitation
n vVd
CF
CTkv B
4n
vn
dV
Stochastic surface potential fluctuations from surface dissipation mixes with static potential differences to give force noise
0 0.2 0.4 0.6 0.8 1 1.2 1.40
0.5
1
1.5
2
2.5
3
3.5
capacitance (pF)
fre
q-i
nd
E
S *
107
1N/2S
slope = 2.44(0.03)e-7 /pFchi2 = 1.1 (2 DOF)
0 500 1000 1500-0.6
-0.4
-0.2
0
0.2
0.4
0.6
time (s)
co
ntr
ibu
tio
n t
orq
ue
(fN
m)
averaged residual torque (1N/2S electrodes,from 200 modulation cyc)
averaged torqueafter LPFilter (f
cut=10mHz)
VMOD
(f=1.25mHz,amp=8V)
theroretical Prediction ( ES
=3.48e-7)
TMOD
• Squarewave modulation technique, 10-17 Nm transient torque resolution
• Detect loss angle d ≈ 3 10-7 for 2 electrode pairs small enough for LISA!
• Waveform and distance dependence consistent with d independent of frequencyPadova, 09/07/2012
19
Angular interferometer: nrad/Hz1/2 sensing for sub-fN force detectionBench-top development
Status: • Working heterodyne modulation bench, homemade phasemeter, and single bounce Mach-Zehnder IFO
• In vacuum rotational noise test summer 2012, torsion pendulum integration Fall-Winter 2012-2013
1 234
3421 “Rotation cancelling” phase combination
Preliminary in-air noise measurements
Padova, 09/07/2012
20Padova, 09/07/2012
Impulse (N*s) vs. tip
orientation
• 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
• 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
Grabbing Positioning and Release Mechanism (GPRM)
Impulse (N*s) vs. tip
orientation