david.barker@LIGO.ORG - posted 08:22, Wednesday 21 May 2014 (12005)
CDS model and DAQ restart report, Tuesday 20th May 2014
model restarts logged for Tue 20/May/2014
2014_05_20 12:14 h1sussr2
model restarts logged for Tue 20/May/2014
2014_05_20 12:14 h1sussr2
Chris, Kiwamu, Lisa, Stefan
After the 45MHz 12.6dB boost this morning we recommissioned the interferometer:
- We realigned the whole interferometer.
- We added ND0.4 filter on REFLAIR_A to avoid saturation.
- We adjusted gains and phases to match REFLAIR_A_RF45, REFLAIR_B_RF27 and REFLAIR_B_RF135.
- First we tried approaching the fringe from the left side. We were hampered by weird demod phases in RF45, as well as the appearance of a resonance in transmission of the y-arm. This probably is the 20 mode of the 45MHz.
- We then decided to approach from the right side of the fringe. There REFLAIR_A_RF45 had the same demod phase as PRMI only.
- We acquired 700 red Hz off resonance.
- We decided to use both its I and Q for PRCL and MICH, because they looked cleaner at low frequency.
- We transitioned at 700 red Hz to RF135.
- We needed the following settings:
REFLAIR_A_RF45 147deg (same for PRMI, and with arms)
MICH GAIN 1.2 (UGF 6Hz), PRCL GAIN 0.8 (UGF 25Hz)
- Next we started walking in. We needed to update the REFLAIR_B_RF135:
73deg (PRMI),
58deg (1kHz offset),
51deg (and MICH GAIN from 1.2 to 1.0)(450Hz CARM offset)
42deg (250Hz CARM offset)
unlocked at 75Hz (up to 1 in ETMY transmission)
- Next attempt identical, but no unlock
40deg (160Hz CARM offset)
At 125Hz CARM offset we noticed that only the y-arm was building up, so we fine-tuned the DARM offset until the arms were symmetrical.
37deg (60Hz CARM offset)
- Then we marched across the river.
Some observations:
- We had ad least a factor of 10 buildup. We should get more, but we were still moving across the fringe rapidly.
- We looked at REFLAIR_A_RF9 but it was puzzling: only a large offset in I.
- We then tried a pure DARM fringe offset, but this made the 3f signals flaky.
- The 3f signals were fine across the resonance.
Attached is a mode scan of the y-arm cavity (ring heater on). Both the DARM offset and the frequency counter are calibrated in mircons for the y-arm. - Our ALS-DIFF calibration is a factor of 3 off - I needed about 3 micron per count from H1:ALS-C_DIFF_PLL_CTRL_OUT, which advertises to be calibrated in micron. - The expected transverse mode spacing for the y-arm is 8.5 kHz (Ritm=2307m Retm=2238.9m, The ITM is also currently being heated weigh the ring heater.). The mode scan measurement is consistent with 8.5kHz, with an or or of about 500Hz. - The problem with that is that the 45MHz sideband is 16261Hz off the resonance, bringing the 20mode nominally to 738Hz . - We suspect the the first side we tired to approach from (left side on the COMM offset slider) was contaminated by this mode. We're now trying the other side.
Thomas, Greg, David HWS - X-end of table continued to be aligned. TCSX - - managed to get the FLIR camera to be connected up to a laptop. Will look to mount on-table tomorrow. - measurements made to calibrate the on-table output power meter. Maximum power of 2.36W for a rotation angle of 82.5degrees. - maximum measured power after the two polarizers was 40.85W. - maximum measured power after the mask was 10.1W --> this would indicate that a maximum power of ~5W could be incident on the CP. Will investigate further. TCSX laser will be left operating overnight.
The low transmission through the central mask is because - that mask was designed for use in the central heating path - the beam size in the annular heating beam path is ~2.5x larger than in the central heating path.
HAM 4
0905 - Richard working on ETM ESD in control room.
915 - Gerardo + John to MY to relieve pressure on valved out vacuum gauge (currently presenting 6e-5 torr)
925 - Jeff & Andres - Live at the H2 Enclosure one night only for OFI move to HAM5 Area and OFI Install.
945 - Travis & Margot & Fil - ACB staging area in LVEA (test stands)
1045 - Praxair delivery
1102 - KingSoft onsite
1130 - Filiberto climbing on top of HAM 1 & 2
1330 - OFI install halted while Arnaud runs some TFs on HAM5
This morning (9:20am-ish) I turned the purge air back up that is plumbed into the East side of HAM4. It had been reportedly turned down yesterday. Soft covers which were weakly billowing are back to full billow.
I re-ennabled the path from SR2 WD to HAM4-ISI WD in h1sussr2.mdl, then re-compiled and restarted it.
The new model is commited under the svn -r8034
Work was perfomed under WP # 4639 which is now closed.
This morning, I aligned the 3 stages of OSEMS (14 in total). This involved some clean filing of one fo the middle stage brackets. A month ago, we noticed that this bracket held the AOSEM already at an extreme in height range, however after beating the streets to see what could be done (via SUS engineering and SUS LLO), we decided to leave it and hope we didn't need more range. The recent SRM mass alignment has sent a small differential pitch up the chain causing this AOSEM to now need more height range. Dam*. The bracket itself has slots for additional height adjustment, however the bracket then runs into the side of the AOSEM itself (hence the poor design statement above). Since we can't do much at this point to fix the range, I disassembled the bracket, removed the AOSEM and filed the bracket down where it hits the AOSEM. I used a Class B file. There is another AOSEM hugging the edge of the mechanical range, but I'm leaving it for now.
With improved mechanical range on this one AOSEM, I was able to align it and the rest of the OSEMs. I've run quick TFs in V, L, and R - all look good so the chamber is ready for OFI installation (and for Jason to post final alignment numbers of SRM).
This is how the magnet looked in the UR M2 AOSEM before bracket "attitude adjustment".
This is the bracket-AOSEM mechanical intereference that didn't work today. (Note, we've reported that on many of our HSTS suspensions at LHO these brackets are at the end of their range, it just bit us this time. I do not know why they are all high at this stage, but the suspension pendulum modes match the model so the pendulum lengths are correct. Our last round of diagnosis on this many months ago was hand washed off that the LHO suspension structures were possibly from a different batch than the LLO ones and therefore there is a mechanical difference in how these AOSEMs are mounted.)
And this is the bracket with my hand-crafted AOSEM relief shape which shoulda been in the bracket in the first place.
Added a ZHL-1A RF amplifier to the 45MHz RF signal which goes to the EOM. The RF power measured at the patch panel in the LVEA is now 25.3dBm from 12.7dBm. There is a 6dB attenuator in front of the RF amplifier which can be replaced with a 12dB one, if the gain is too high. The modulation depth was measured in alog 9395. There seems to be a 2dB loss between the LVEA patch panel and the EOM. If correct, the modulation depth is now 0.3 and the 3f-signal strength about 70 times higher. With a little bit of cable and barrel magic the phase was restored to within 1 degree.
Arnaud and I have made some changes to the SUS guardian. We broke up the graph such that the requestable states are now idle states that don't actually change the state of the suspension:
The dark blue states, which are the requestable states, now only check the alignment and watchdog status. The reason for this change is so that guardian being in e.g. the ALIGNED state actually indicates that suspension is fully aligned. Previously guardian would enter the ALIGNED state, even before the offsets had fully wrapped to their alignment values. Other guardian nodes that might be watching the SUS guardians for optic alignment would therefore be misled. This just makes the state more explict.
I also removed the goto flag from the RESET (was SAFE) state due to a bug I discovered in guardian. The bug is that if there is a goto on the graph, then the INIT state will not be executed. This is something I need to fix in guardian. In the mean time, I just made all the desired transitions explicit.
I wanted to mention a couple more changes that Arnaud and I made to the main SUS guardian module:
Arnaud will write another follow-up comment once these changes are all committed.
The changes were commited under the svn. Details can be found under the OpsManual
On friday night, the wind was high(~25mph), and the arm was hard to lock. Although the angular motion of the test masses was not particularly different than on a quiet night. First attachement shows the oplev spectra from friday night, when the wind was ~25mph. second attachement shows spectra from yesterday night with a 5mph wind.
To note :
We tracked down the problems we had in the past windy nights to be related with the ALS tidal tuning , but it is still good to make these plots with the OpLEv signals.
However, I think your plots didn't turn out the way you wanted to. There is only YAW in the second attachment.
Also, it would be easier to make a comparison if you put windy/quiet curves for each DOF in the same plot. Thanks!
thanks for noticing!
Attached are some other plots :
1. wind at corner and endy stations between may 17th/may 20th. High winds references are marked in orange, low winds is in green
2. Spectra comparison of ground sensors (HEPI STS) at end and corner stations with different winds. Blue and pink curves are during high winds (blue = may 17th, pink = may 18th). Red is during low winds (may 19th). From top to bottom rows : ETMX ETMY and ITMY. From left to right : X Y Z degrees of freedom.
3. Spectra comparison of oplevs during high winds (may 18th blue curve) and low winds (may 19th red curve) for ETMx ETMy and ITMy top to bottom. Left column is pitch, right column is yaw.
Resonant arms and words of wisdom.
It seems that some of the length degrees of freedom had an offset. It is not clear at this point which DOF was off from the operating point. The POP DC basically did not show a buildup at all when the arm was at a high value. The REFL DC did not become a smaller value. Plus, the demodulated signals at 1fs had an offset without any PDH-looking waveform during the arm was flashing. The attached shows the moment of the lock loss. You can see how they behaved odd.
After the people left, I made a few more attempts of this locking procedure last night. It worked robustly. The funny REFL9I offset was also seen consistently.
After the CARM offset was completely removed, I then got rid of the 135I and 135Q offsets to see if this helps the power buildup in the arm cavities. This actually made them worse --- the buildup in the arm cavities decreased by a factor 2 or so. Since the interferometer dropped the lock afterwards, I did not explore a bigger offset in the 135 signals.