jeffrey.kissel@LIGO.ORG - posted 15:26, Wednesday 16 April 2014 - last comment - 15:47, Wednesday 16 April 2014(11392)
H1 SUS ETMY UIM & PUM Coils Balanced
J. Kissel Thanks to Thomas' incremental improvements to the H1 SUS ETMY optical lever (see LHO aLOGs 11356 & 11387), he got the noise low enough that we were comfortable pushing forward with the large suite of measurements needed to get the QUAD ready for ISC use. the first on this list is the coil balancing on the middle two stages, which has now been completed (following instructions in LHO aLOGs 9453, 9079 and parameters taken from LHO aLOG 10493) with the results below. The final balanced gains are H1 SUS ETMY Channel Balanced COILOUTF Gain L1 UL -0.957 L1 LL +1.021 L1 UR +0.976 L1 LR -1.042 L2 UL +0.964 L2 LL -1.039 L2 UR -0.959 L2 LR +1.034 The SNR was particular good this time around (thanks to TBetter instead of TCrappy filters on the ISI? [Less wind/ better ground motion]), so I was able to determine these values to 0.25% (instead of the usual 0.5%). The first page of each attachment shows the ASDs of the optical lever signals during a pringle drive at each respective stage, before and after balancing. The second page compares the coherence between blanaced and unbalanced. In summary, DOF Reduction Factor @ 4.1 [Hz] L1 Pringle to L3 P > 9.4 (peak is in the noise, and only ~70% coherent) L1 Pringle to L3 Y 38 L2 Pringle to L3 P > 1.8 (peak is in the noise, totally incoherent) L2 Pringle to L3 Y 33 Now we begin measuring L P Y of each stage to P&Y of the test mass, to gather all data necessary for - iStage L to test mass P&Y for frequency dependent length to angle decoupling, - iStage P to test mass Y & iStage Y to test mass P for frequency dependent alignment decoupling, and - iStage P to test mass P & iStage Y to test mass Y for alignment plant compensation.
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Measurement Details
-------------------
Coil Driver Configuration:
BIO State Compensation
UIM 1 ON
PUM -2 OFF
Demodulator filters used:
SIG band pass: BP4.0Hz = butter("BandPass",2,3.5,4.0)
DEMOD I & Q low-pass: CLP50mHz = cheby1("LowPass",2,3,0.05)
Demodulator Drive Parameters (for both measurements)
Freq [Hz] Amp [ct] Sin [ct] Cos [ct]
P 4.0 115000 10000 10000
Y 4.0 115000 10000 10000
SEI Configuration (for both measurements):
HPI: Level 1 Isolation, "Pos" position sensor only blend filters
ST1: Level 3 Isolation, "TBetter" blend filters (in all DOFs)
ST2: Level 3 Isolation, "TBetter" blend filters (in all DOFs)
Measured using a 200 second average (shorter than yesterday) of the demodulated signals, i.e.
tdsavg 200 H1:SUS-ETMX_LKIN_P_DEMOD_I_OUT H1:SUS-ETMX_LKIN_P_DEMOD_Q_OUT H1:SUS-ETMX_LKIN_Y_DEMOD_I_OUT H1:SUS-ETMX_LKIN_Y_DEMOD_Q_OUT
H1 ETMX L1
Demod Phase [deg] Unbalanced Value [ct] Balanced Value [ct]
P 77 I +1.311 pm ~0.2 -0.017 pm ~0.2
Q -0.157 pm ~0.2 -0.132 pm ~0.2
Y 78 I -9.510 pm ~0.2 -0.063 pm ~0.2
Q -0.243 pm ~0.2 -0.236 pm ~0.2
H1 ETMX L2
Demod Phase [deg] Unbalanced Value [ct] Balanced Value [ct]
P -33.5 I -0.243 pm ~0.5 -0.044 pm ~0.5
Q -0.060 pm ~0.5 -0.003 pm ~0.5
Y -33.5 I -3.874 pm ~0.5 -0.041 pm ~0.5
Q 0.267 pm ~0.5 -0.121 pm ~0.5
note that the quote pm values are the by-eye, peak-to-peak amplitude of the demodulated signal which oscillates with a ~25 sec period. I quote values to a much higher precision because I'm averaging over 200 seconds.
To perturb the PIT or YAW balancing by 5%, 1%, 0.5%, and then by 0.25%:
/ligo/svncommon/SusSVN/sus/trunk/Common/PythonTools/perturbcoilbalance_fourosem.py H1 ETMX L1 [PIT/YAW] [0.05/0.01/0.005/0.0025]
/ligo/svncommon/SusSVN/sus/trunk/Common/PythonTools/perturbcoilbalance_fourosem.py H1 ETMX L2 [PIT/YAW] [0.05/0.01/0.005/0.0025]
Exact balanced values:
Measured using a simple command line caget, i.e.
caget H1:SUS-ETMX_L2_COILOUTF_UL_GAIN H1:SUS-ETMX_L2_COILOUTF_LL_GAIN H1:SUS-ETMX_L2_COILOUTF_UR_GAIN H1:SUS-ETMX_L2_COILOUTF_LR_GAIN
H1 ETMX L1
Coil COILOUTF Gain
UL -0.957006
LL +1.02136
UR +0.976339
LR -1.04199
H1 ETMX L2
Coil COILOUTF Gain
UL -0.964279
LL +1.03047
UR +0.95947
LR -1.03428
Of course, these values are set at arbitrary precession, they're rounded to the values quoted in the main entry (a) because the measurement uncertainty is no better than 0.25%, and (b) the MEDM screen does not display out to higher precession, so further precision would not be visible.