alignment status & plans
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1 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment status & plansAlignment status & plans
2 Commissioning meeting, Cascina 02.04.2007H. Heit mann
22ndnd modulation frequency modulation frequency
Virgo mod. (6.26 MHz)
2nd mod. (8.35 MHz)
2nd modulation frequency:absolute (demodulated) reference for common end alignment
(not available with one fmod)
Previously aligned with ITF reflection Q21_DC
IMC mod. (22.4 MHz)
2nd mod. on the same EOM => line forest => difficult
Solution: 2nd EOM=> Much less problemsbut modulation must be weak (m=0.01 instead of 0.17)for avoiding perturbations => to be investigated
3 Commissioning meeting, Cascina 02.04.2007H. Heit mann
22ndnd f fmodmod layout layout
6.26 MHz8.35 MHz
WSR10 alignment layout
4 Commissioning meeting, Cascina 02.04.2007H. Heit mann
22ndnd f fmodmod: results: results
8 MHz modulation is working Low modulation index => Q22 signal noisy => use at LF
Common end loop adaptedError signal remains Q21_DCAbsolute Q21 position set by shifting until Q22_AC = 0
(Alp loop; stopped in science mode)
Alternative possibility“Mix” Q22_AC (LF) <=> Q21_DC (HF)
One error signal; filters in sensing matrix
Advantage: absolute DC reference is kept during science mode
Q21_DCQ22_8 MHz
5 Commissioning meeting, Cascina 02.04.2007H. Heit mann
B7_q1
B7_q2
B7
B8_q2
B8
B8_q1
WE
WI
NI NE
BS
PR
End mirror beam centering - beforeEnd mirror beam centering - before
BeforeDSP Drift controlQD error signalB8_q1_DC B8_q2_DCB7_q1_DCB7_q2_DC
6 Commissioning meeting, Cascina 02.04.2007H. Heit mann
B7_q1
B7_q2
B7
B8_q2
B8
B8_q1
WE
WI
NI NE
BS
PR
End mirror beam centering - nowEnd mirror beam centering - now
NowAlp Drift controlAlp error signal7...8 Hz line on NE/WE tx/tyLocking correction in z=> control input mirrorsNoise reductionbut: upconversion 10-15 Hz ?!
10 Hz
beforeafter
(high ISYS noise!)
7 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment noise in dark fringeAlignment noise in dark fringe
Differential end mirror tx mode almost limiting=> more power on Q1p diode + whitening filter=> alternative: improve corrector cut-off (but: need all margin for high LF gain)
G. Vajente Automated alignment noise projections (10 min.)
Coherence
8 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Recent Gc-Ali upgradesRecent Gc-Ali upgrades
Sensing – Filtering – Driving availableDriving switch needed during thermal transient(switch NE-WE => Common-Differential)
Noise injection For measurement of open loop transfer functions
Filtering gain change on-flyFor migrating all gain changes from DSP to Gc
Sensing Filtering DSP
Global control
Driving
Noise
9 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment OL transfer function measurementsAlignment OL transfer function measurementsDifferential end tx
Excellent fit with Matlab model
Gain adjustment => matrix calibration
Differential end ty
? Less excellent fit
But still good in the important region (a few Hz)
10 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Other improvementsOther improvements
Thermal transient robustnessImproved by switching on 1. differential 2. common end alignmentDriving matrix NE/WE => NE+WE/NE-WE after thermal transientPR alignment acts on reference mass
Local control on marionette remains on
High gain filters (end mirror control)Further tuning needed Sometimes more gain than needed
=> Rather invest in HF cut-off
HistogramDiff end tx error signal
11 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Plans up to scientific run IPlans up to scientific run I
Improve alignment stability (filter work)Sometimes oscillations during thermal transientCheck stability in bad weather conditions
Reduce alignment noise10-50 Hz: alignment noise starts becoming important
Error signal improvement (B1p: more light + preshaping)
Filter tuning (LF gain / HF cutoff trade-off)
Continue transfer function measurementsLine injections for better coherence
Understand model deviationsMeasure resonance frequencies: rad. pressure effects?
Update sensing matrix
Continue alignment globalizationMore logical system: all gain adjustments in Gc, …
12 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Plans up to scientific run IIPlans up to scientific run II
Common mode error signal improvementCreate composite error signal (mix Q22_ACLF + Q21_DCHF)
Observe beam centering loopsImprove if needed (up-conversion, better centering, …)
Centering of input mirrors?TBC
13 Commissioning meeting, Cascina 02.04.2007H. Heit mann
To be done if neededTo be done if needed
Switch BS/ISYS <-> NI/WI controlLA on NI/WI mirrorsBS/ISYS steer beams in arms
Globalize other LA degrees of freedomPR, BS
PR alignmentKeep LC on marionette on?
Optimize IMC alignment filtersReduce LF beam jitter (higher gain)
Increase 8 MHz modulation indexFirst understand where locking signal perturbation comes from
End
15 Commissioning meeting, Cascina 02.04.2007H. Heit mann
Alignment configurationsAlignment configurations
C7 14/09 – 19/09/2005
tx IB PR BS NI NE WI WE ty IB PR BS NI NE WI WE
10 d.o.f. fast alignment
WSR1 08/09 – 11/09/2006
tx BM PR BS NI NE WI WE ty BM PR BS NI NE WI WE
6 d.o.f. fast alignment; input beam and BS control
WSR10 09/03 – 12/03/2007
tx BM PR BS NI NE WI WE ty BM PR BS NI NE WI WE
7 d.o.f. fast alignment; input beam and BS control
XX Linear alignmentXX LA (ref. mass)XX Drift controlXX Local controlXX DC error signalXX DC + AC err.sig.
16 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 sensing matrixWSR10 sensing matrix
BMS PR BS NI NE WI WE ThetaX 0.5 B1p_q1_ACq4 B2_q1_ACp 2 B5_q1_ACq -0.5 B8_q1_ACp -1.5 B2_q1_DC 1 B7_q1_DC -1.5 B7_q2_DC 1 B8_q1_DC -0.8 B8_q2_DC
BMS PR BS NI NE WI WE ThetaY -0.6 B1p_q1_ACq4 B2_q1_ACq 2 B5_q1_ACq 0.4 B8_q1_ACq 4 B2_q1_DC 1 B7_q1_DC -1 B7_q2_DC 1 B8_q1_DC -0.7 B8_q2_DC
* Filtered in Gc sensing
17 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 alignment control overviewWSR10 alignment control overview
Beam
Diode
Demod.
Loop
Arm diff.
B1p Q Fast
Arm common
B2 12 for
centering
- Fast
PR B5 1 Q Fast
BS B8 1 P (tx)Q
(ty)
Fast (tx)Drift (ty)
NI B7 1+2 - Drift
WI B8 1+2 - Drift
BMS B2 1 P (tx)Q
(ty)
Drift
18 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 alignment filteringWSR10 alignment filtering
Sensing Filtering DSP
Sensing Filtering 1DC
Filtering 2Initial
Filtering 3Boost
DSP
PR tx--- --- --- --- Ref.mass
+ mario LC
PR ty--- --- --- --- Ref.mass
+ mario LC
End tx--- --- INITIAL BOOST ---
End ty--- --- INITIAL BOOST ---
Global control
Driving
19 Commissioning meeting, Cascina 02.04.2007H. Heit mann
WSR10 alignment drivingWSR10 alignment driving
Sensing Filtering DSP
Driving 1Initial_Driving
Driving 2Driving
CommonEnd => NE => NE+WE
Differ.End => WE => NE-WE
Global control
Driving
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