Bonding as an assembly technique in upgrades to aLIGO and detectors like ET and KAGRA R. Douglas 1,...
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Bonding as an assembly technique in upgrades to aLIGO and detectors like ET and KAGRA R. Douglas 1, A. A. van Veggel 1, K. Haughian 1, D. Chen 2, L. Cunningham
Bonding as an assembly technique in upgrades to aLIGO and
detectors like ET and KAGRA R. Douglas 1, A. A. van Veggel 1, K.
Haughian 1, D. Chen 2, L. Cunningham 1, R. Glaser 3, G. Hammond 1,
G. Hofmann 3, J. Hough 1, M. Masso Reid 1, P. Murray 1, R. Nawrodt
3, M. Phelps 1, S. Reid 4, S. Rowan 1, Y. Sakakibara 2, T. Suzuki
5, C. Schwarz 3, K. Yamamoto 2 1 SUPA, Institute for Gravitational
Research, University of Glasgow, Glasgow, UK 2 ICRR, University of
Tokyo, Tokyo, Japan 3 Friedrich Schiller University, Jena, Germany
4 SUPA, University of the West of Scotland, Paisley, UK 5 High
Energy Accelerator Research Organisation, Tokyo, Japan Amaldi
Gwangju, June 2015
Slide 2
LIGO-G1500838 GEO600, aLIGO, and advanced VIRGO use
quasi-monolithic fused silica test mass suspensions with superior
thermal noise performance at room temperature Hydroxide catalysis
bonding (HCB) is used in all to attach interface pieces to the
mirrors, allowing attachment of the fibres (which are welded) We
are considering upgrades to detectors at room temperature (A+ and
ET- HF) and various cryogenic temperatures (Voyager, ET-LF, KAGRA)
Introduction 2
Slide 3
LIGO-G1500838 Chemistry 3 This method can create strong,
durable bonds. Chemistry of bonding between silica surfaces:
Dehydration Polymerisation Hydration and Etching Bonding solution
with an excess of free OH - ions being released from into the
Slide 4
LIGO-G1500838 Feasibility study: how? 4 Can we bond sapphire
and silicon using HCB? Yes, we can Silicon surfaces must be
oxidised to facilitate reliable bonding Chemistry is different for
sapphire: aluminate chains Are there other jointing techniques that
may be suitable? Indium bonding but only under compression and if
suspension is not baked out What is the strength of bonds in
conditions consistent with those of cryogenic suspension, assembly
and operation?
Slide 5
LIGO-G1500838 Bond Strength 5 Two types of strength tests
carried out: 4 point bend tester to measure tensile strength and a
torsional shear strength tester. Load, F Bond 4 contact points d L
Bonded sample Where T is the torque, a is the length and b is the
width of the cross-section of the sample Where b is the breadth of
the sample l
Slide 6
LIGO-G1500838 Temperature 120 100 80 60 40 20 0 Shear strength
[MPa] R.T.77 K 6 Cryogenic strength of HCBs between sapphire
40x10x5 mm samples, 10x5 mm M-to-M-plane bond in the centre Results
published Douglas et al., CQG, 2014 Room temperature pH 12 Pristine
samples M-to-M 120 100 80 60 40 20 0 Shear strength [MPa] Sodium
aluminate Sodium hydroxide Potassium hydroxide Sodium silicate
Bonding solution Load, F Bon d 4 line contacts d L l Bonde d sampl
e Tensile strength [MPa]
Slide 7
LIGO-G1500838 Bond strength: sapphire, curing time 7 Load, F
Bon d 4 line contacts d L l Bonded sample Curing time for bonds
between silica has been found to be ~4 weeks. All C-C samples broke
clean across the bond. Strength within error the same for the 3
different curing times. Curing time of sapphire doesnt appear to be
longer than 4 weeks. Investigations are ongoing. Strength for A-A,
M-M and C- C within error the same. Bonded sapphire sample 5x5x40
mm. C-C plane. 5x5 mm bonding surface
Slide 8
LIGO-G1500838 Bond strength: silicon, thermal cycling 8 Load, F
Bon d 4 line contacts d L l Bonde d sampl e Check the effect of
thermal cycling on the strength of bonds as suspended silicon
masses are likely to go through multiple thermal cycles in their
lifetime. 40 bonds tested in set 1, 28 bonds tested in set 2.
Thermal cycling done in Jena ~4 K ~293 K, 2 hours per cycle.
Oxidised silicon sample 10x5x20 mm Boron doped P-type ~150 nm dry
thermal oxide Observations: Overall average strength doesnt change
Two strength groups (thought to be linked to bond quality).
Slide 9
LIGO-G1500838 Bond strength: questions remaining? Silicon What
is the minimum oxide layer thickness for ion-beam sputtered
coatings? What is causing difference in strength between different
sets of bonds: bond quality? How can we best to assess this? Can
strength/mechanical loss be improved through heat/vacuum treatment?
What is the curing time? Sapphire Influence of thermal expansion
differences between different crystal orientations on bond strength
when bonding e.g. c-a plane or c-m plane? Influence of polishing
process/surface damage on strength. Literature study suggests
surface reactivity higher for mechanically polished surfaces as
opposed to pristine surfaces Can strength/mechanical loss be
improved through heat/vacuum treatment? Bond strength of sapphire
not polished or cut on specific crystal plane? 9
Slide 10
LIGO-G1500838 Thermal conductivity 10 T1T1 T2T2 Heater used to
induce heat flow Heater and temperature sensor used to thermally
stabilise the clamp LL Clamped silicon sample Thermal conductivity
has now been measured of: 1.Silicon-silicon HCB bonded cylinders (
25 mm x 76 mm) down to 30 K (Lorenzini, ET meeting Jena, 2010)
2.Silicon-silicon HCB bonded samples (5x5x40 mm) down to 8 K
3.Sapphire-sapphire HCB bonded samples (Poster C. Schwarz, D. Chen,
ET meeting 2014, Lyon). 4.Sapphire-sapphire indium bonded sample
Results suggest drop in thermal conductivity is very small.
Slide 11
LIGO-G1500838 Summary 11 HCB between silicon and sapphire have
been extensively demonstrated to be strong enough for typical
gravitational wave detector suspensions Thermal cycling of HCB
bonded silicon does not negatively impact strength of bonds but
more work is needed to be able to assess bond quality Thermal
conductivity measurements of HCB and indium bonds appear to be high
enough for suspension attachments. Aim: Understand better the
influence of cross-sectional size on thermal conductivity For more
information see Marielle van Veggels recent GWADW talk
(LIGO-G15008) which includes details on loss measurements.
Slide 12
LIGO-G1500838 Thank you for your attention 12 Thank you for
your attention Any questions?
Slide 13
LIGO-G1500838
Slide 14
Bond strength: what do we know? Silicon In Glasgow we bond with
sodium silicate solution. (Potassium hydroxide is also possible,
see Dari et al., CQG, 2010) Using a wet thermal oxide layer, we
need 50 nm oxide layer to get reliably strong bonds (Beveridge et
al., CQG, 2011) Strengths tested at R.T. and at 77 K Ion beam
sputtered oxide layer is an excellent and probably more practical
alternative (Beveridge et al., CQG, 2013) Average strength values
are 2040 MPa (depending on type of material, crystal orientation,
temperature of test. Strength at 77 K higher than at R.T. Recent
thermal cycling tests (3,10 and 20 times down to ~8 K) of - silicon
(2 sets tested), suggest that the average stays constant. We are
developing techniques to assess the quality of bonds during the
bonding procedure to ensure only high quality bonds are accepted.
14
Slide 15
LIGO-G1500838 Stress due to thermal expansion differences
15
Slide 16
LIGO-G1500838 Bond mechanical loss, overview Silica-silica HCB
bond made with sodium silicate solution @ RT Bond loss: 0.11 0.02
(Cunningham, CQG, 2010) Silica-silica HCB bond (same as above)
after 3 years and after heat treatment 150 C for 48 hours. Bond
loss: 0.06 0.01 (Haughian, thesis, 2012) Silicon-silicon HCB bond
made with sodium silicate solution @ RT. Not an ideal bond
(offset). Bond loss: 0.27-0.52 (Haughian, thesis, 2012)
Sapphire-sapphire HCB made with sodium silicate solution @ RT
temperature Bond loss @ R.T. 0.03 0.01 Bond loss @ 20 K (3 - 7)x10
-4 1x10 -4 Sapphire-sapphire indium bond Bond loss @ 20 K (2 3)x10
-3 (Talk K. Yamamoto, ET meeting 2014, Lyon). 16
Slide 17
LIGO-G1500838 17 Thermal noise associated with HCBs in aLIGO
Hild, S., CQG. 29 (2012) 124006 In aLIGO thermal noise arising from
bonds was to be 10% of the total thermal noise budget @ 100 Hz
Thermal noise budget @ 100 Hz is 2.5 10 -24 / Hz Bond thermal noise
budget per test mass 7 10 22 m/Hz, (T010075- 01,2009) Calculated:
5.4 10 22 m/Hz ) assuming bond loss of 0.11 at 293 K Assumptions
for calculations following: bond thermal noise budget < 10% of
overall thermal noise budget @ 100 Hz Ear size (where unknown):
same ratios and average shear stress (0.17 MPa) as aLIGO.
Slide 18
LIGO-G1500838 Thermal noise from bonds for cryogenic detectors
18 Name detectorA+ 2 ET-LF 1 (option 1)ET-LF 1 (option 2) TM
materialSilicasiliconsapphire Temperature TM [K]29310 Bond area 1
ear [mm x mm]39x11845x136 Assumed bond thermal noise requirement
[m/ Hz] 3 10 -22 2 10 -22 Bond loss [-] *1.1 10 -1 **1.1 10 -1 *7
10 -4 Calculated expected thermal noise (15%) [m/ Hz] 5.3 10 -22
1.4 10 -22 1.2 10 -23 ** Assumed value (bond loss) silica-silica
bond @ R.T* Measured value