One of Two Bounce/Roll Mode Dampers Tuned for H1 ITMY

J. Kissel, T. Sadecki, S. Appert

The Bounce/Roll Mode Dampers (BRDs, D1500228) are to be pre-tuned to the measured highest vertical (a.k.a. "bounce") and roll resonances of the QUADs. CIT has graciously pre-tuned them for us following the procedure, T1700142, but unfortunately tuning is a graceful art of wiggling the masses around within the slop of the screws and it's *very* sensitive, and vulnerable to change with shipping.

As such, we wanted to 
    - get some practice tuning them ourselves, because we'll have to do so for the three new test masses we're getting,
    - check that the resonance frequencies survived shipping to us, and
    - adjust the bounce frequency for ITMY, because they were tuned to a typo frequency.

After some fumbling for about an hour with the B&K pulse software, Stephen helped us just create a new template in the PULSE B&K system that did what we wanted.
However, since we only need to measure the frequency, and our method of storage of the answer is just writing it down, I'm going to switch to using an SR785 tomorrow. The B&K software is overly complex with far too many distracting / confusing bells and whistles to just take a spectrum. Further, we're going to need the B&K laptop for measuring HAM-ISI blade, new baffle, suspension cages resonances chamber side with the hammer and accelerometer configuration, and I don't want to lose that much time again to dragging around the system and reconfiguring it. I can tune both the BRDs and the ISI TMDs with the SR785 + Laser Vibrometer setup quietly in the optics lab, and leave the B&K + Accelerometer + Hammer set up out on the floor.

The tuning process itself took us about 3-4 hours for one. We half to tune 2 per test mass.
Thankfully the tuning is spaced out by quite a bit, and we can knock out ITMY's now.

Eventually our results will end up in E1700285, but for now, 
BRD S/N  007
  Blade                     Bounce (Hz)      Roll (Hz)   Freq Resolution (mHz)
  ITMY Target                9.831            13.93          10 mHz
  As Received                9.813            13.938         50 mHz
  After Tuning               9.863            13.938         20 mHz
(Target - After) / Target     0.3%             0.05%

We acknowledge that the bounce frequency is not great, but we had already spent 2 hours on tuning it, then switched to the roll side, tuned that for an hour, and just *measured* the bounce again, and found it had changed. Likely from the many iterations of on-vs-off of the measurement stand and the adjustment jig while tuning the roll side was enough to disturb the bounce side.

Since the target matching is to 1% the bounce frequency looks fine.
Good work.

35W Front End NPRO Swap - Day 3

J. Oberling, E. Merilh

Short Version

The new NPRO is now aligned through the 35W FE, with a final output power of 39.0 W.  We will change the pump diode currents for the NPRO and MOPA so the output power is closer to 35 W (this will increase the lifetime of both the NPRO and the FE diode box).  The final steps for tomorrow are:

• Measure beam profile of FE, adjust mode matching if necessary.
• Check FE alignment through HPO, adjusting as necessary.
• Injection lock HPO to FE.
• Recover PSL subsystems (PMC, FSS, ISS).

Long Version

We began the day by aligning the new NPRO to the EOM, AOM, and FI; the NPRO diode current remained at 0.900 A through this process.  The beam height of this NPRO was not too dissimilar to the old one, but the elevation angle was different, to the point that the beam, when centered on the EOM and AOM, would not pass the lens in front of the FI (FE_L2).  To get the beam through the FI, we had to adjust the lens after the initial polarization optics (it has no designation on the PSL table drawing, so I'll call it FE_L0 for the purposes of this alog), at the same time adjusting the EOM and AOM to follow the beam.  Once we got the beam through the FI we started aligning to the new irises we placed on Tuesday using mirrors FE_M2 and FE_M3.  Most of the adjustment was done vertically (adjusting the beam up), with very little horizontal adjustment needed (adjusting left if looking in the direction of propagation).  At one point we had to adjust lens FE_L0 again as we were clipping on the FI, but needed to continue to move the beam up to get through the irises; this then required another adjustment of the EOM to prevent clipping.  Once the beam was through the irises, we measured the NPRO power after FE_L0 and at the entrance to the MOPA:

• After FE_L0: 66.8 mW
• MOPA entrance: 48.0 mW

The NPRO diode current was then turned up to it's nominal value of 2.35 A and the same measurements were taken; we also measured the power at the MOPA exit (all measurements done with an Ophir 10W power meter):

• After FE_L0: 1.94 W
• MOPA entrance: 1.72 W
• MOPA exit: 0.129 W

I adjusted mirrors FE_M4 and FE_M5 to get the beam through the MOPA; the final power meter reading was 1.40 W.  We then installed the 30W power meter as the next step would finish with a FE output power > 10 W.  We turned the MOPA pump diodes on at 10 A and measured the output power, and stepped them up to a final value of 30 A:

• 0 A: 1.32 W
• 10 A: 1.32 W
• 15 A: 1.82 W
• 20 A: 2.76 W
• 30 A: 6.12 W

Ed then aligned the NPRO beam through the MOPA using mirrors FE_M4 and FE_M5; at the end of this alignment the output power was 16.35 W.  We then had to install the 200 W power meter (this is what happens when you don't think ahead, we should have used the same power meter for these measurements).  The FE diode currents were increased to their nominal operating values of 46.3 A for D1 and D2 and 49.7 A for D3 and D4 (the pump diodes are chained in pairs), with a stop at 40 A along the way.  The output power of the FE was measured at each point:

• 30 A: 17.3 W
  • This is why we should have used the same power meter, simply changing the meter gave us a 1 W "increase" in the output power of the FE...
• 40 A: 29.9 W
• Operating currents: 36.3 W

Ed then aligned the NPRO beam through the MOPA using the same mirrors; after this alignment the FE is outputting 39.0 W (Go Ed!).  We can decrease the operating current of both the NPRO and the MOPA so the output power is closer to 35 W; this is beneficial as it will extend the lifetime of both the NPRO and the MOPA diode box.  At this point we called it a day, as we were both starting to get tired.  The final steps for tomorrow are:

• Measure the beam profile of the FE and adjust the mode matching if necessary.
• Check FE alignment through HPO, adjusting as necessary.
• Injection lock HPO to FE.
• Recover PSL subsystems (PMC, ISS, FSS).

Removed IP8

Kyle R., Gerardo M., Mark D., Tyler G. 

We vented IP8, removed it and installed a zero-length reducer having a 1.5" angle valve pump port.  The gate valve leaked at a comparable leak rate as that of IP7's gate valve but this is of little consequence as we used a pump cart to evacuate the volume between the closed gate and the 1.5" pump port valve.  I will leave the Main Turbo pumping the Diagonal volume overnight.  

Ops Shift Summary

TITLE: 09/14 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning

Jason and Ed are still in the PSL enclosure.

LOG:

16:05 UTC Jason and Ed to PSL to start alignment
16:16 UTC Gerardo to end Y to take pictures
17:02 UTC Jeff B. to cleaning area
17:31 UTC Corey to optics lab
17:41 UTC Jeff B. back
17:51 UTC TJ to optics lab to retrieve item
17:52 UTC Hugh to LVEA to lock the HAM3 HEPI
18:39 UTC Corey back
19:10 UTC Karen to mid Y to clean
19:39 UTC Karen leaving mid Y and going to mid X
19:46 UTC Hugh to LVEA to reseat HAM3 CPS cards due to excess noise
20:00 UTC Travis to LVEA to drop off equipment
20:08 UTC Karen leaving mid X
20:13 UTC Travis back
20:18 UTC Jeff K. and Travis to optics lab
20:38 UTC Jason and Ed back to PSL
22:07 UTC Sheila to squeezer bay

23:24 UTC Jason and Ed done for the day

23:29 UTC Travis and Jeff K. done in optics lab

Sheila is back

Optical Lever 7 Day Trands

variations due to vent and ISI trip/recovery

Added new idle state in manager path

Jim asked if I could add a requestable state for the ISIs to be damped but HEPI isolation loops off. This is in the path, but there is no requestable state there. I added it for both the HAMs and BSCs and tested it before loading it into all of the SEI managers.

This is common code and will be brought up at tomorrows SEI meeting. It is not changing any functionality, just adding a stopping place.

SEI_ETMX graph attached.

LY pressure

After hard closing corner station beam tube boundary gate valves (GV 5,7) on Tuesday, noticed the pressure at LY went up from ~ 3e-9 Torr to 7e-9 Torr (LX did not rise). A leak, whether external, annulus o-ring, or surface outgassing, has been known for a long time (Kyle made log entries of early {inconclusive} leak hunting). In an effort to troubleshoot, I soft closed GV6 this morning to bound CP1. The pressure at PT-124 (beam tube side of GV6) fell after closing this valve. I will leave it closed for the day to see how the pressure trends, but it looks like there could be a leak somewhere in CP1 or maybe in a flange inner o-ring. Will leak check as time permits.

Unfortunately CP1's pressure gauge has been off since closing valves on Tuesday due to some weird grounding (?) issue with Beckhoff? I reset it but this particular CC is taking a while to turn back on. It is a known problem that when we toggle the LOTO switch on valve, it trips the gauge (x and y side). 

 

Ringdown Q measurements of the 6th and 7th harmonic for the QUAD violin modes - After Earthquake

These ringdown measurements, of the LHO QUAD suspensions violin mode 6th and 7th harmonics, were obtained 2 days after the big Earthquake hitting LHO on the 20170706. For this analysis I used 17 hours of detector data in Low noise state from "20170708 06:30:00" UTC. None of the 6th and 7th harmonics were being actively damped or excited. Although clearly the Earthquake excited these harmonics well enough to get very nice ringdowns.

In this analysis, a line tracker (iWave) was applied over each of the identified 6th and 7th harmonic frequencies, locking onto them.

I give next the results for those frequencies that show ringdowns. I also attach 'png' plots which shows; in each column the mode monitored with the top plot being the frequency tracked as a function of time, the middle plot is the 'log(Amplitude)' (natural logarithm of the mode's amplitude). The red dashed lines are respectively the median of the tracked frequency and the fitted first order polynomial to the 'log' of the mode's ringdown. The plot at the bottom shows the Phase deviation respect to the linear fit.

6th Harmonic

Mode frequency (Hz)          Q  

2836.347                           792664427

2837.676                           735427842

2839.189                           667931233

2841.245                           645741246

2842.507                           503371109

2843.141                           669024332

2843.431                           659048452

2844.486                           715255321

2846.824                           675302066

2847.020                           608809212

2848.206                           659351953

2849.444                           534289274

2849.583                           405660077

2850.597                           574906401

2853.482                           712952420

2853.710                           401649469

2857.727                           724216344

2858.379                           624072692

2864.457                           770311177

2866.174                           671254082

2868.132                           427751583

2878.644                           498367912

2878.701                           429105364

2880.567                           621008999

2880.854                           614386214

2882.491                           585658907

 

The 7th harmonic values will be added below in the comments.

H1 ISI CPS Sensor Noise Spectra Check - Weekly FAMIS #6915

Everything looks normal save for HAM3 which shows a slight elevated CPSINF_H2.

Removed IP7

Kyle R., Gerardo M., Mark D. (Apollo), Tyler G. (Apollo) 

Spun-up and valved-in Diagonal Turbo pump (NOTE: Valve only partially opened as actuator mechanism is galling and will stick permanently soon).  Isolated and vented IP7 with room air.  Removed IP7 from isolation gate valve.  Installed zero-length reducer with 1.5" pump port valve and evacuated volume between closed gate and zero-length reducer.  Installed blank flange on IP7.  

Leaving the Turbo valved-in overnight and will only close following the removal of IP8 tomorrow so as to minimize valve cycling -> hopefully valve will close one more time before failing completely.  

2500 L/sec large ion pumps (IPx) are being removed as opportunities arise so as to be refurbished.

35W Front End NPRO Swap Progress - Days 1 and 2

J. Oberling, E. Merilh, J. Bartlett

Progress report on the last 2 days of NPRO swap work.

Day 1

Day 1 was more of a prep day than anything.  In the morning we began by shutting down the HPO and 35W Front End (FE) lasers.  We then turned on only the NPRO and measured the current output power; measured 1.35 W.  We then checked the current alignment through the 2 irises in the 35W FE, and found them both to be off; both were off to the right (if looking in the direction of beam propagation) by 1-2 beam diameters.  In addition, the beam was low on iris 1 by ~1 beam diameter and high on iris 2 by ~1 beam diameter.  We set 2 additional irises in the beam path to capture the current beam alignment, seeing as how the pre-installed ones were so far off.  We then proceeded to check the current alignment through the irises in the HPO (each mode matching lens has an iris attached to it).  The beam was slightly low and to the right on the iris on MM1, and very slightly high on the iris on MM2 (once again assuming one is looking in the direction of beam propagation).  At this point we broke for lunch.  The afternoon was devoted to the install of the new PSL water manifold, detailed here.

Day 2

Part of the morning was spent finishing up the manifold install.  Once that was completed, we checked the NPRO beam alignment through the EOM and the Faraday isolator (FI) in the FE.  We found the beam low and to the right on the EOM, almost clipping on the bottom of the entrance aperture.  It was hard to judge how the beam was going into the Faraday, but on the output side it was exiting high by ~3-4 mm.  I then installed another iris at the end of the mode matching rail in the HPO; not sure how useful this one will be, but it is at least capturing the current alignment.  I would have liked to install a 2nd one, but there was no room in a space that would be visible.  At this point we began discussing how to remove the NPRO without dismantling the FE box.

We ended up taking off the side panel by the NPRO (to access the clamp on the back leg of the NPRO) and removed 4 screws from the back panel of the FE box; we also removed the PD that monitors the NPRO power.  We then carefully bent the back panel just enough to give us room to maneuver the NPRO out of the box.  We removed the feet from the old NPRO and installed them onto the new one.  The new NPRO was then slid into the FE box, being careful to not get caught up in the cables that route underneath it.  We then broke for lunch and the 1pm safety meeting.

Once back in the PSL enclosure we hooked up the new NPRO (S/N GDP.1235944.7974), using the old power supply and cable, and set the settings on the power supply to match the data sheet for the new NPRO.  For the record, these are:

• NPRO crystal temperature: 26.50 °C
• Diode Current: 2.35 A
• Diode A temperature: 18.30 °C
• Diode B temperature: 16.00 °C

The NPRO was then turned on, and there was light (yay!).  After a warm up period, we measured the output power of the NPRO to be 1.864 W.  To account for differences in output polarization between the 2 lasers, we then adjusted the quarter- and half-wave plates that sit directly in front of the NPRO to maximize the output power.  The most we could get was 1.894 W.  For alignment purposes, the operating current of the NPRO was then reduced to 0.900 A, which yielded an output power of 52 mW.  The beam alignment was checked at the EOM, AOM, shutter, and FI: the beam was low and left on the EOM, low and right on the AOM, high on the shutter, and did not reach the FI (best I can guess it was bouncing off the roof of the shutter and scattering out).  Not too bad for a rough "by eye" placement.  The NPRO position was then carefully adjusted until the beam was horizontally centered on the EOM.  Due to beam height differences between the 2 NPROs (no 2 are exactly alike), the only way to adjust the beam height on the EOM was to either move the EOM or the lens responsible for focusing the laser onto the EOM.  I elected to move the lens, and centered the beam on the EOM entrance aperture.  The beam was now low and centered on the AOM, and high on the shutter (but not as high as previously); a slight output through the FI can now be seen, so, progress!  We called it a day at this point, alignment will continue in the morning.

Ops Day Shift Summary

TITLE: 09/13 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
LOG:

Jeff B. in PSL enclosure working on H2O manifold
14:41 UTC Visitor through gate for safety audit
14:43 UTC Karen to warehouse
Richard working by HAM6
15:08 UTC Richard back
15:29 UTC Richard and Filiberto to HAM6
15:33 UTC John showing visitors from India around
15:53 UTC Chandra to LVEA
15:54 UTC Ed to CER to help Filiberto terminate cables
15:58 UTC Visitor through gate to see Chandra
16:21 UTC Christina starting cleaning of HAM2
16:23 UTC Hugh to LVEA to lock HEPIs
16:26 UTC Jason to PSL
16:39 UTC ISI HAM2 WD tripped. Cleaning chamber.
16:57 UTC Contractor through gate to do insulation work for Bubba
17:04 UTC Ed to PSL to help Jason with alignment
h1nds crashed, kernal panic, Carlos restarted
17:20 UTC Contractor through gate to do insulation work for Bubba
17:36 UTC Travis to LVEA to look for tooling
17:39 UTC Richard to LVEA with Albert L. and Tim N.
17:43 UTC Travis back
17:49 UTC Richard back
17:52 UTC Richard to LVEA to see Filiberto
18:01 UTC Richard back
18:48 UTC Visitor through gate to see Marc P.
18:57 UTC Hugh back
19:49 UTC Betsy to LVEA
20:00 UTC All hands safety meeting
20:15 UTC Visitor through gate to see Betsy
21:35 UTC Hugh to LVEA to lock HEPIs
21:43 UTC Richard to LVEA, CER
21:45 UTC Ed and Jason back to PSL
22:12 UTC Marc to CER
22:16 UTC Marc back
22:59 UTC Hugh back
23:07 UTC Ed back, Jason still in PSL enclosure

WHAM5 HEPI Now Locked on Stops

All LVEA HEPIs are now locked except HAM3.

Install PLS Chiller Manifold

Jason, Jeff B.,

   Yesterday we installed the new PSL chiller manifold. After fixing several small fitting leaks this morning the PSL chiller is back up and running. The flows and pressures all look good. 

   In order to fit the manifold under the table, I need to change the manifold supply and return fittings from 3/4" straight FNPT to 3/4" barb to, 3/4" elbow (90)FNPT to 3/4" barb. Finding this fitting that is safe for use in a DI water system is proving to be a bit of a challenge. I have several queries out right now. 

         

AS72 revised. Might actually be okay?

TVo, Hang

Yesterday I said that the AS72 scheme might not be working based on that the Q-phase signals vanished for SRM when we applied 600mW ITMX CO2 power (nominal 300mW). However, this might not be a fair claim, as the current scheme could not hold the IFO locked for more than 1 hour under 600mW CO2X power either. More importantly, it would be unlikely for the IFO to be parked at such a bad TCS setting in the future. Therefore we redid the measurements, focusing on examining the stability in the vicinity of the nominal TCS setting, and it seemed that the AS72 scheme had a decent performance if the TCS was not way off. 

 

CONCLUSIONS:

1. The AS72 scheme works for the current IFO.  (A possible sensing matrix: A_Q -> SRM, B_Q -> BS).

2. The AS72 scheme for SRM is more robust than AS36 if the TCS is at least good-ish (within +- 100mW from nominal)

3. BS signals are in general more robust against thermal lensing than SRM signals. This is the case for both AS36 and AS72.

4. The current SRM ASC using AS_A_RF36_I seemed not a great choice. The B_RF36 sensor had a much better response. 

 

DETAILS: 

    i). We measured SRM/BS response at different CO2X power levels, ranging from 200mW to 500mW w/ 100mW stepsize. The nominal sensing matrix with 300mW CO2X was shown below. As a reference point, the noise level for the AS72 is about 0.3. As a caveat, so far we only measured the response amplitude; the sign is not yet available and will be provided with offline analysis. 

300mW IX CO2 power

		A_I	A_Q	B_I	B_Q
SRM	RF36	88	190	780	800
	RF72	2.0	1.3	0.77	0.52
BS	RF36	110	2800	1150	2200
	RF72	0.36	0.73	1.2	1.1

where the bold-orange numbers are the ones used in current RF36 ASC, the red-italic numbers are possible error signals for the RF72 scheme.

    ii). How the sensing signals varies under different TCS setups are shown in the first two plots attached (first one for SRM, second for BS). 

    iii). Because we needed to drive SRM/BS in angle hard enough to see the signal in RF72, the drive cross-coupled to length loops even we notched the ASC loops. Therefore we also drive the SRCL/MICH in length to match the cross-coupled amplitude from angular excitations. The l2a leakage was below the noise floor for RF72 so it should not contaminate our measurements significantly. For RF36, the SRCL to SRM pitch leakge seemed as large as the angular signal itsef for A_I, the one currently used (!!!).

    iv). In case people are interested in seeing how the TCS affecting other loops, in the third figure we show the data trend where we changed the ITMX CO2 power from 300mW to 500mW. The SRM/SR2 can drift as much as 2-3 urads due to thermal effects. Also ~1h after the CO2 laser power change, the IFO became unhappy and we have to revert the CO2 power back to 300mW to remain locked.

AS72 WFS adjustments; 118MHz mod depth measurements.

1. Matching the gain of each quadrant:

When we reached DRMI locked last night, we adjusted the gain of each AS72 WFS quadrant s.t. the 205 Hz line after the first demod all having roughly the same amplitude. 

2. Adjusting the phase:

We drove SRM in length at 4Hz last night from 04:40:00 to 04:47:00, Sep 08, 2017 (UTC). Then offline we computed the transfer function from AS_AorB_RF72_I1_DEMOD_I to AS_AorB_RF72_Ij_DEMOD_I at 4Hz. Each quadrant's phase is then adjusted to compensate for the tf phase. For future reference, the tf phase were:

Relative phase for AS72 WFSs

	seg 1	seg 2	seg 3	seg 4
A	0	8.6	-4.1	-15.0
B	0	3.8	7.6	4.3

3. 118MHz mod depth measurement:

We also use the driven line to measure 118MHz SB's mod depth relative to 9MHz. 

	optical gain	PD resp.	whitening	anti-whitening	filter gain	final resp in cnts/rtHz @ 4Hz
AS36	gamma_9	-12dB	12dB	-12dB	2.8	132
AS72	0.5*10*gamma_118	-24dB	45dB	-24dB	1.	0.42

where in the opt. gain, the 0.5 accounts for that the AS72 has one more demod (half of the signal lost at 2xf_dmd), 10 for 118MHz DRMI transmission relative to 9MH (assuming dithering SRM in length only changes 45MHz and 9/118 serves as a static reference field); the PD resp was from T1300488; the final cnts had a bw of 1/256 sec. 

We thus have gamma_9/gamma_118 ~ 1, 600, consistent with what Kiwamu measured in 37061.