The Test Mass - INFN

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
Padova, 09/07/2012
1
Scopo di LISA PAthfinder
Sensitivity of LISA
Soppressione delle accelerazioni parassite a meglio di 3×10-14 ms-2√Hz
(10 volte meno stringente di LISA)
Padova, 09/07/2012
2
LISA PF a Trento
RICERCATORI
Dolesi Rita
Giuliana Russano
Vitale Stefano
Weber William
Antonucci Federica
Tu Hai Bo
Congedo Giuseppe
Ferroni Valerio
Wen Shyang
Cavalleri Antonella
Hueller Mauro
TECNOLOGI
Benedetti Matteo
Bortoluzzi Daniele
Bosetti Paolo
Cristofolini Ilaria
De Cecco Mariolino
Da Lio Mauro
Mezzena Renato
associato
associato
associato
associato
associato
associato
da associare
da associare
da associare
da associare
Non associabile
associato
associato
associato
associato
associato
associato
associato
LISA PF in Europa
Ricercatore
Dottoranda
Prof. Ordinario
Ricercatore
Assegnista
Assegnista
Assegnista
Assegnista
Assegnista
Ricercatore (CNR FBK)
90
100
80
90
100
100
100
100
100
90
Tot RICERCATORI (FTE)
9,5
Co Co Co
50
Ricercatore
Prof. Associato
Ricercatore
Ricercatore
Prof. Associato
Prof. Ordinario
Tecnologo E.P.
40
70
10
10
10
10
10
Tot TECNOLOGI (FTE)
Tot TECNOLOGI (FTE) >10%
1,6
1,1
LISA PF in Italia
Collaborazione INFN LISA PF
AQ, FI, NA,RM2 eTN: circa 30 persone (19 FTE)
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
3
Padova, 09/07/2012
Management
ATTIVITA’ DEL GRUPPO di TRENTO
Principal investigator della missione LISA Pathfinder
Testing
a terra
del sensore
gravitazionale
----- Il monitoraggio dello
sviluppo
del programma
e delle
prestazioni
con pendoli di torsione
----- Attività di “shadow engineering” :
•supportoTesting
all’indagine/soluzione
sull’hardware
a terra delladelle
fasenon-conformances
di rilascio in voloriportate
della test
mass
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
4
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.
Science Module: H/W complete - except
-LTP Core assembly
-Micro-propulsion system: identified more that one viable alternatives, including a coldgas 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.
LANCIO NEL 2014
The test has been a success.
Padova, 09/07/2012
5
GRS on ground testing with torsion pendulum
fiber
Autocollimator beam

TM
shaft
X sensing electrodes
Padova, 09/07/2012
6
GRS prototypes and LPF-like Test Masses :
increasing representativeness
NOW !
GRS
4 mm gaps,
LPF geometry
Mo / Shapal EM
Mo / Sapphire LPF EM
LPF-like TM
LPF FM-replica
nm roughness !
Lightweight : empty TM in gold coated Al
Padova,FM
09/07/2012
Same
TM finishing 7
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
8
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
9
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
10
Issue:
Int. ref.:
Date:
Sheet:
GPRM
sign Description
2
573DD0001
25.04.2007
6 of 33
The Test Mass release testing
•
+Z
The Grabbing Positioning and Release Mechanism (GPRM)
is designed to hold and release the TM into free fall.
TM
Electrode
housing
•
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).
-Z
•
d grabbed positions of the Grabbing finger
Gold coated surfaces (tip/TM) develop
strong adhesive bonds.
•
Adhesion between the tips and the TM
produces a pull (a momentum transfer)
during release.
t title
echanism assembly GPRM procurement
nt
of work for the GPRM
Issue
•
The verification of the requirement of
Date
3
Nov. 06
1
25.10.2005
residual velocity is part of the LISA PF
ground testing activities.
•
t title
The Transferred Momentum Measurement
Issue
Date
release task group report
1
21.07.2005
finger alignment budget
3
7.3.2007
rabbing devices accuracy analysis
1
12.10.2006
E vibration test report
2
29.11.06
B test report
Padova, 09/07/20121
Facility is developed to characterize the TM
release velocity
9.11.06
11
Composizione LISA PF Trento
RICERCATORI
Dolesi Rita
Giuliana Russano
Vitale Stefano
Weber William
Antonucci Federica
Tu Hai Bo
Congedo Giuseppe
Ferroni Valerio
Wen Shyang
Cavalleri Antonella
Hueller Mauro
TECNOLOGI
Benedetti Matteo
Bortoluzzi Daniele
Bosetti Paolo
Cristofolini Ilaria
De Cecco Mariolino
Da Lio Mauro
Mezzena Renato
Ricercatore
Dottoranda
Prof. Ordinario
Ricercatore
Assegnista
Assegnista
Assegnista
Assegnista
Assegnista
Ricercatore (CNR FBK)
90
100
80
90
100
100
100
100
100
90
Tot RICERCATORI (FTE)
9,5
Co Co Co
50
Hueller Mauro
Co Co Co
50
TECNOLOGI
Benedetti Matteo
Bortoluzzi Daniele
Bosetti Paolo
Cristofolini Ilaria
De Cecco Mariolino
Da Lio Mauro
Mezzena Renato
Ricercatore
Prof. Associato
Ricercatore
Ricercatore
Prof. Associato
Prof. Ordinario
Tecnologo E.P.
40
70
10
10
10
10
10
Tot TECNOLOGI (FTE)
Tot TECNOLOGI (FTE) >10%
1,6
1,1
Richieste 2013 (preliminare)
Nessuna
40 richiesta ai Servizi
Ricercatore
70
Prof. Associato
Missioni
10
Ricercatore
Consumo
Ricerca
10
Ricercatore
Manutenzione
10
Prof. Associato
Inventariabile
Prof. Ordinario(pompa turbo 40010l/s, lettore di pressione
calibrato,
RGA,
10 posizionatore
Tecnologo
E.P.4 controller per motor,
lineare piezoelettrico)
Costruzione apparati (specchi per interferometro e per
Tot TECNOLOGI (FTE)
1,6
pendoli, refurbishment GRS Replica)
Tot TECNOLOGI
1,1
Totale
Richieste (FTE)
2013 >10%
8000
9000
6000
33000
30000
86000
Padova,
09/07/2012
12
EXTRA
Padova, 09/07/2012
13
Thermal gradient related forces:
LPF GRS replica after bake-out at 110 C
Radiometer
Radiation
pressure
Temp dependent
outgassing
dFx
AP
8

 kR
 k rp T03  AQ(T0 ) 2
d (Tx )
4T0
3c
T0


2

pN  P   293K 
pN  T0 
pN Q(T0 ) 
   293K 


  27

 18
k R  5  
k rp 
  40
 
4
nJ
K
K
K  1.4
 3 10 K   T0 
 10 Pa   T0 
 293K 


s 

3
-10
7
x 10
T(K)
6
289.20
295.46
304.30
dForce/dT (N/K)
5
Slope
(N/K/mbar)
2.47e-4
2.39e-4
2.75e-4
stat. error
(N/K/mbar)
2e-6
3e-6
4e-6
Intercept
(pN/K)
26
36
53
stat. error
(pN/K)
3
1
4
Slope affected by the accuracy of the Ion P gauge, which is nominally 15%
4
Close to the expected @293 K
3
2
@ P=2e-8 mbar
1
0
0
0.5
1
1.5
Pressure (mbar)
2
2.5
-6
x 10
Radiometer 23 pN/K  5 pN/K
T dependent Outgassing probably dominates
Padova, 09/07/2012
14
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
15
Random TM charging andDC stray potential: LISA Pathfinder GRS
replica
1/ 2
2
Compensazione dc bias
S
1/ 2
F
2e EFF C
  x   EFF 

 x  0.2 fN/Hz 1/2  


CT
x
 10 mV   1000 /s 
-Vcomp
+Veq
+Veq-Vcomp=0
 f 


 1 mHz 
-Veq
-Veq+Vcomp=0
+Vcomp
Force
+Veq-Vcomp=0
-Vcomp
+Veq
-Veq+Vcomp=0
+Vcomp
-Veq
compensation to <1 mV demonstrated
Error due to shear force compensation not present with TM charge,
order of 10 mV control with real TM charge variation
Padova, 09/07/2012
16
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
17
Experimental investigation of electrostatic dissipation
Thermodynamic force noise source for LISA and experimental gravitation
Stochastic surface potential fluctuations
from surface dissipation mixes with static
potential differences to give force noise
v n  4 k BT
vn
F 
V
3
VMOD (f=1.25mHz,amp=8V)
theroretical Prediction (  ES=3.48e-7)
0.2
TMOD
0
-0.2
2.5
slope = 2.44(0.03)e-7 /pF
chi2 = 1.1 (2 DOF)
2
1.5
1
0.5
-0.4
-0.6
0
1N/2S
averaged torque
after LPFilter (fcut=10mHz)
0.4
C
V vn
d
3.5
freq-ind ES * 107
 contribution torque (fNm)
averaged residual torque (1N/2S electrodes,from 200 modulation cyc)
0.6

C
500
1000
time (s)
1500
0
0
0.2
0.4
0.6
0.8
capacitance (pF)
1
1.2
1.4
• Squarewave modulation technique, 10-17 Nm transient torque resolution
• Detect loss angle  ≈ 3 10-7 for 2 electrode pairs  small enough for LISA!
• Waveform and distance dependence consistent with  independent
of frequency
Padova, 09/07/2012
18
Angular interferometer: nrad/Hz1/2 sensing for sub-fN force detection
Bench-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 FallWinter 2012-2013
Preliminary in-air noise measurements
1 2
4 3
  1  2   4  3 
“Rotation cancelling”
phase
combination 19
Padova,
09/07/2012
•
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
Impulse (N*s) vs. tip orientation
•
Extrapolation to in-flight release
Grabbing Positioning and
Release Mechanism (GPRM)
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
LISA Pathf
CVM
CVM Design R
LISA CVM
Padova, 09/07/2012
8
BUDGETS
20