model restarts logged for Sat 29/Nov/2014
2014_11_29 14:44 h1fw0
2014_11_29 23:26 h1fw1
both unexpected restarts. Conlog frequently changing channel reports attached.
Sheila, Elli, Dave, Stefan We spent some time to automate the transition to a CARM offset of 30ppm. In particular: - The DRMI looks ok with the new TCS settings. We did not retune the loop gains - that should probably still be done. - Noticed that with the new TCS central heating on ETMX the WFS loops in DRMI behave differently. - We increased the gain of PRM pitch WFS loop by 10 to H1:ASC-PRC1_P_GAIN = -0.06 - We increased the gain of PRM yaw WFS loop by 20 to H1:ASC-PRC1_Y_GAIN = 0.02 - We turned off the SRM WFS loops - they seem to be unstable with the new TCS heating. - We moved the transition to RF DARM to a setpoint of sqrt(TR_X+TR_Y)=1 (was 2). This seems more robust. - We tweaked the PREP_TR_CARM state to give the Beckhoff servo some time to converge - We rewrote the transition to CARM_TR in Guardian - it's now really smooth. - We added and commissioned the states RF_DARM, CARM_30pm, TR_QPD_TRANSITION and CARM_20PM. They do what was discussed in alog 15318. - The challenge is at the CARM_20PM step - it doesn't want to stay there fore too long... The only troublesome spot is the ALS_COMM CARM fringe finder. It often grabs the wrong one, and advances to DIFF before the serve setled. Definitely needs work. The the CARM reduction steps from DRMI_LOCKED to TR_QPD_TRANSITION worked twice in a row flawlessly.
Let it locked in TR_QPD_TRANSITION at 1:07am , just to see how stable the whole thing is.
One of the PSL AC units outside the control room/LVEA was pulled out of its anchors and blown over sideways.
Last Wednesday we reset the HEPI length actuator which is used for tidal correction back to zero. The accumulated value at this point was 0.40 mm. The apparent tilt seen by the optical lever was –7.1 µrad in pitch and +5.9 µrad in yaw. However, most of this apparent tilt is due to longitude-to-angle coupling in the optical levers; for ETMX E1200836 lists 20.9 µrad/mm in pitch and 11.9 µrad/mm in yaw. With 0.40 mm we expect to see 8.4 µrad in pitch and 4.8 µrad in yaw.
After resetting the tidal actuator the cavity was locked and realigned. The misalignment was mostly in yaw where we adjusted by -1.6 µrad which is also seen in the optical lever. This was required for both ETMX and TMSX. The pitch alignment was minor with 0.5 µrad for ETMX and nothing for TMSX.
Summarizing, the observed longitude-to-angle coupling is within 15% of what we expect and the ETMX HEPI length-to-yaw coupling is about –4.0 µrad/mm.
The weather has been somewhat violent this weekend. Daniel was asking about the temperatures in the LVEA/VEAs so I attach a recent plot.
Note that the ZONE Average is the LVEA average of ~64 sensors so I also include the worst looking zone, ZONE3B, which is the Y beam manifold area. The most remote sensor of this zone is down by the cryopump near the exit vestibule - this sensor is affected by north winds which leak through the doors. Perhaps an oplev in that region is suffering.
YEND is not as stable as XEND.
I restored the ODC monitoring threshold settings (they were somehow lost). I noticed that the H1:PSL-FSS_MIXER_OUTPUT took a jump around 6/19/2014, and was slowly trending upward since. For now I increased the ODC threshold H1:PSL-ODC_FSS_MIXER_LT_TH to 1.3.
no restarts reported. conlog frequently changing channels report attached.
Here is a plot of wind at EY today. Shown is 10 hours of the mean and max.
Dave O, Stefan, Elli
Yesterday Stefan and Kiwamu turned on the ITMX CO2 laser was turned on to 440mW and the simple michelson was left locked. See alog 15328.
Today we looked at the effect this had on the contrast defect. When the CO2 laser was turned on, the contrast defect improved untill it was almost zero after about 35 mins. The contrast defect then got worse as the ITM continued to heat up. The ITM takes >4hrs to reach thermal equilibrium after the CO2 laser is switch on, as measured in alog 14742.
Using Aidan's measurments from alog 14742, we re-calculated the power needed to minimise the contrast defect to be 255mW. To do this, we fitted a curve to the time dependent behaviour of the spherical power (see picture). This fit was
y=aexp(-bx)+c
where
a=-8.14e-5
b=-4.27e-4
c=7.9e-6
We adjusted the ITMX CO2 laser power to 255mW. The michelson broke lock early this morning possibly due to strong winds. We were unable to relock the Michleson interfereometer possilbly because of ongoing strong winds and hence could not see the change in the contrast defect, that is the next step. We have left the CO2 power on at 255mW and so the next time the michelson locks we will have the optimum contrast defect.
Relocked the dark Michelson at 2:55pm. But it still often drops lock due to the current wind conditions. Attached is another plot that better shows the y-axis scale. For reference: the dark counts in H1:LSC-ASAIR_B_LF_OUT_DQ are -1.78cts. The best values in the cureve are about -0.2cts. The freely swinging Michelson peaks at 1890cts, suggesting an achievable contrast defect of 8.5e-4.
The winds are gusting to 55-60mph. I leave the MICH loop off, because it just keeps saturating.
With the new heating (0.255W) H1:LSC-ASAIR_B_LF_OUT_DQ bottoms out at 0.25cts. The dark offset is -1.8cts. We started off (before the heating exercise) with about 3cts. Thus we improved the contrast by a factor of (0.25+1.8)/(3+1.8)=0.43 = 1/2.3.
Expected sideband power:
tM = sin 2πfMla/c
PM = Γ2/2 tM2 Pin
With la = 0.05 m, fM = 45.5 MHz, Γ = 0.28, and Pin = 1890 cts, we get
tM = 0.048,
PM/Pin = 90 ppm and
PM = 0.17 cts.
This gives a contrast defect of 0.99 x 10–3 at 225 mW.
no restarts reported. Conlog frequently changing channel list attached.
J. Kissel In summary: (1) Turn on X, Y, and Z sensor correction for HAMs 2 and 5, using the standard Hua Filter scheme (see T1200285), with tuned gains. (2) Use LLO's M1 OSEM Damping filters and gains. (3) Turn off optical lever damping so we don't have worry about maintaining optical levers to as great care. ------- This continues (and hopefully resolves) the study of why PR3 and SR3 (both HLTSs) are angularly noisy, began by Kiwamu (see LHO aLOG 15048), and continued in a prior aLOG by me (see LHO aLOG 15154). I had started today thinking that I would do the usual full modeling suite, and this time include the optical lever damping. But after a little bit of exploring, I found that the L1 HLTS, H1 PR3, and H1 SR3 were using in various, completely different damping schemes, the performance of the optical levers are radically different, so a noise projection would be difficult, and the L1 vs. H1 HAM ISIs perform significantly different. So, since a "representative" model seemed impossible, as did the thought of making an individual model for all four suspensions and comparing, I've just spent the time gathering proof of what we need to do to make them much better. Once we get all of the above three steps completed *then* I'll make a full model suite of the performance. Here's the details explaining how I can to these conclusions. They're supported by the first and only attachment. (3) Turn off optical lever damping. Pages 1 and 2 of the attached show the wide variety of performance on the optical levers. Page 3 and 4 show the H1 the levers are in loop, but only with a bandwidth from 0.4 to 1 [Hz] (see design for SR3 in LHO aLOG 14719). There seems to be some effort toward rolling off the noise, but it seems quite unrelated to the actually noise performance of the levers at high frequency. LLO *had* used optical lever damping sporadically on L1 PR3, but they're currently not using it and haven't since Oct 17 2014. Given that the damping is so much strong and the input motion is so much smaller, this makes sense that its not needed. Further -- even with L1 SR3 aligned, the location to which, presumably, the optical lever has been centered -- the performance of the optical lever spectra is not limited by residual ground motion of the optic. So it's most certainly unusable for control. Including optical levers in the local damping scheme complicates the remaining dynamics of the suspension (and perhaps more to the point, the subsequent modeling of it), and getting used to relying on them means they'll be left on and most certainly reinject noise above their bandwidth unless the loops are custom tailored to the ever-evolving optical lever noise. So if we can achieve the same level of local damping with the top mass OSEMs, and improve the performance of the ISIs, let's do it. (1) Turn on X, Y, and Z sensor correction for HAMs 2 and 5, using the standard Hua Filter scheme (see T1200285), with tuned gains. Pages 5 through 7 compare the performance of the HAM2 and HAM5 ISIs, highlighting the degrees of freedom which contribute to L, P and Y at the optic. Remember, the L at the suspension point is the dominant contributor to L *and* P at the test mass, at all frequencies (see pgs 5 and 33 of the second attachment to LLO aLOG 7907). In turn, X and RY (for PR3) and Y and RX (for SR3) are the dominant contributors to L at the suspension point. Y at the optic is all Y at the susp. point, which is all RZ of the table. Though I'm not sure what the H1 HAMs have worse performance than the L1 HAMs between 2 and 8 [Hz] (that should be investigated further), I certainly know that the *drastic* difference between 0.3 [Hz] and 1 [Hz] is because LLO has sensor correction for all DOFs turned on. Poking around at LLO, I've found that the sensor correction is nothing particularly fancy -- it's just the standard Hua filter scheme, with a single, gain only Match filter at the output to tune better match STS gain to the displacement sensors (those gains are a correction of ~10-20%, matched to a ridiculously high precision [where its unclear if the precision is needed]). HAM2 uses the HAM2 STS (STS A), and HAM5 uses the HAM5 STS (STS C), as expected. At the first L and P resonances of the HLTS, there's a possibility for the following improvement if we get to LLO's level of isolation: Frequency [Hz] Table DOF Performance Ratio 0.64 HAM2 X 6.23 / 0.11 = 56.6 HAM5 Y 5.29 / 0.08 = 66.1 0.74 HAM2 X 1.87 / 0.03 = 62.3 HAM5 Y 1.42 / 0.02 = 71.0 and as we know by now, its these lowest resonance frequencies that dominate the RMS motion of the optic. All this being said, except for between 0.2 [Hz] and 0.6 [Hz], LLO is kicking the snot out of the "requirements." Nice job! I'm very confident that we can do just as well here at LHO. The trick will be to get the HAM2 and HAM3 sensor correction up at the same time, so that we don't introduce and relative low frequency noise in the recycling cavities. P.S. There're some pretty nasty sharp features and associated harmonics in the L1 HAM5 ISI's RX and RZ spectrum ... we should get that fixed -- they're obviously electronic, particularly ugly, and might affect pulsar searches. (2) Use LLO's M1 OSEM Damping filters and gains. Pages 8 and 9 highlight the DRASTIC difference in damping loop filters. I hesitate to call the H1 HLTS filters a "design," because I know they were copied from the QUADs (hence the 0.43 [Hz] and 0.56 [Hz] resonant gains in the L and P filters, respectively). There's no reason at all we shouldn't just switch to the LLO design immediately -- these aren't under global control so we need not worry about changing any global control transfer functions, and though I haven't modeled it (yet) the increase in gain at just about all frequencies, especially what's focused at the *actual* first L and P modes of the HLTS. With the switch, we would get a factor of 16.2 increase in gain at 0.75 [Hz] in the L loop (which presumable will hit the same mode in P as well), and a factor of 44 increase in gain at the first, 1 [Hz], Y resonance. With steps (1) and (2) complete, that means we can expect to improve the Y and P motion at the optic, at the main resonances by as much as three orders of magnitude.
I attach a screenshot of the configuration the L1 HLTS damping filters are in that replicate page 8 of the above attachment. Note that there are two filters in FM6 and FM7, called "Plant" and "x[number]," where "number" is the equivalent EPICs gain. These are useful to copy over because they represent, well the plant and the EPICs gain. BUT there're never meant to be turned on in-loop, they're only for offline foton study. In page 8 of the attachment, for example, I have the "x[number]" filters on for both sites, so their overall gain can be easily compared. We can, of course, turn on the "x[number]" filters and keep all of the EPICs gain at -1.0, which I prefer, in the future.
I've added the Hua filters to all the HAM ISI's. There was a BSC script to do this that I spent some time modifying, so we now don't have to copy and paste from other chambers. Currently the top level script lives in the HAM4 control scripts folder (called Loading_Sensor_Correction_Filters_H1_ISI_HAM4.m), but there were some subroutines from the BSC that needed modifying to work with HAM, as well as a master FIR file in the HPI userapps filterfile folder, all of which I copied and made HAM specific. None of the original files were changed, I just made HAM specific versions. I'll try turning stuff on at HAM6 first, and get some plots, then talk to commissioners about times to try turning this on elsewhere and making measurements with cavities to try to optimize, if they'll let me.
Jim: we do *not* want to use Hua sensor correction filters in any DOF for the BSCs, see the third item in SEI aLOG 645. So, don't worry about getting them into the BSC filter banks.
As per Jeff's suggestion (2) above, and with the commissioning crew's approval, I have loaded new filters into the empty filter bank slots on all 6 Damping DOF's of both the PR3 and SR3 M1 stages. None of the new filters have been enabled, and the damping loops are currently unchanged. They/we might try enabling the damping filters later tonight or tomorrow. At Kiwamu's suggestion, I'll also look at gathering comparison data for the different damping regimes now that they are available here at LHO on PR3, as well as installing them on SR3. Attached are the screen snapshots of the PR3 and SR3 DAMP loops with the existing set of filters enabled, and new slots filled. Note, before they are used, the available gain filters in FM7 needs some tweeking as the LLO gains do not match the LHO loop gains.
I did not copy the FM1, FM2, FM5, or FM10 filters.
Betsy and I have enabled the new M1 damping filters (see attachment).
The gains have not been changed.
The SR3 oplev damping has been turned off. It may have to be retuned because of the M1 changes.
Stefan, Kiwamu,
Today we had high seismic due to high wind. This lead to a difficult situation in ALS DIFF where the ETMX actuators saturated more frequently than usual. So we were not able to get to the same point as yesterday.
We moved on to the TCSX test. We engaged ASWFS_B_RF45_Q to align BS with the simple Michelson locked. We then activated the TCS X laser at around 17:45:00 local time and adjusted to the power to 0.444 W as requested by Aidan. We are leaving the Michleons locked.
Kiwamu, Stefan, Dave O, Elli
Power spectrum from last night's lock attempt as detailed in alog entry 15323.
Comparing BSC and SRM control signals at cavity buildup of 75 at GPS 1101128136 and cavity buildup of 115 at GPS 1101128173.
There is a broadband increase in both control signals, including an increase at the 60Hz periscope peak.
Kiwamu, Lisa, Matt, Stefan - First we verified that the CARM to transmitted light transition still works today (arm power 0.32*single arm). - Next we repeated the transition to AS_45_Q, and turned on the gain scaling (arm power 2.0*single arm). - We also immediately turn on AS_45_Q gain scaling with TR_X (arm power 2.0*single arm). - Then we turned on the DHARD WFS (arm power 2.0*single arm): whitening gain of 9dB: H1:ASC-AS_B_RF45_WHITEN_GAIN 3 H1:ASC-AS_B_RF45_Q_PIT_GAIN and H1:ASC-AS_B_RF45_Q_YAW_GAIN gain to 0.1 input matrix AS_B_RF49Q to DHARD H1:ASC-INMATRIX_P_8_6 1e-4, same for yaw H1:ASC-DHARD_P_GAIN 0.3 , same for yaw control filter modules FM1 (integrator) and FM5 (Low pass LP0.2) output matrix: H1:ASC-OUTMATRIX_P_7_8 = 1 , H1:ASC-OUTMATRIX_P_8_8 = -1 , H1:ASC-OUTMATRIX_Y_7_8 = 1 , H1:ASC-OUTMATRIX_Y_8_8 = 1 - Then we went to a hgher arm power (arm power 32*single arm). - We noticed that TR_X starts saturating right around there, so we intended to switch to the QPDS, but had an unreasonable amount of trouble for this simple operation. - Still trying... Attached is a plot of the CARM transfer function. It also includes a transmitted power ratio of the QPD's and the LSC PD's.
The message is that we increased the build up in the arms up to ~30 times the single arm power (CARM offset ~ 40pm). The first plot shows a trend of the arm power transmission. In the first (incredibly stable!) lock we made several attempts to reduce the CARM offset further, but the IFO started to become unstable, so Stefan was quickly going back to a larger offset to prevent unlocking. It turned out that the problem was a saturation in the X TR diode (clearly visible in the second attachment). The following locking attempts were killed by the (in principle) straightforward task of switching to the in-vac TR QPDs. The problem turned out to be that the signals that we were carefully matching were one before power normalization, and the other one afterwards..
Later, we reduced the CARM offset further down to approximately 20 pm at which point the arm build up was 100 times higher than that of the single arm.
As reported in Stefan's previous log, we were having a difficulty in switching the TR sensor from TR_X(Y)_A to ASC_QPD_Bs. Keeping using TR_A actually introduced a broad noise peak at around 70 Hz which showed up all the LSC loops. Stefan then carefully adjusted their relative gains and therefore the transiotion went very smooth. We did not see an obvious transient in any of the LSC signals during the transition of the TR sensors. Then we further reduced the TR_CARM offset to -15 counts without a problem. We did not see a gain peaking or any sign of significant change in the optical gain of DARM. So we did not have to chage the DARM gain. At this point we saw REFL_DC almost going down as low as 50% and also POP_DC increasing significantly. We kept running the DHARD ASC loops.
We stayed at this point for a while, but then it seemed that the DRMI dropped the lock. Before the lock loss, RMS of the SRCL control signal slowly kept increasing. It could be a coupling from CARM which was contaminating the SRCL control. We may want to decrease the SRCL UGF in order to prevent the SRM suspension from saturating.
Nice going, you are almost there. (The old grouch (for Lisa's benefit)