HAM6 Vent Plan for the Week of April 4, 2016

B. Weaver, H. Radkins, V. Sandberg

 

LHO WHAM6 Vent Plan for 2016 April 04 - 08

DCC Document: E1600092, “HAM6 - ISI Damper Install”

https://dcc.ligo.org/LIGO-E1600092

 

APPROVED work to be done in order of importance:

Install HAM ISI Dampers assemblies (Jim W., Nutsinee K.). 

Retune Tuned Mass Dampers (TMDs).

 

DCC Vent Documents referenced in this plan:

• E1600084, “Installation and Testing Procedure for HAM ISI Dampers”

a)   D1500469 Drawing documents for ham blade dampers

b)   D1600085  Drawing documents for GS13 dampers

c)   D1500200  Drawing documents for flexure dampers

d)   D0900703  Drawing documents for Tuned Mass Dampers (TMDs)

e)   E1100963  Retuning the TMDs

f)   T1500580 HAM ISI Damping Study - Mittleman

g)   G1500880  Damping Tests on Flexture Demo - Lantz

• E1100742 Payload layout update for HAM6
• D0901822 HAM6 Top Level Chamber Assembly
• E1201035 aLIGO Chamber Entry & Exit Procedures
• M1100039 Hanford Checklist - HAM Door Removal
• M1300464 Procedure for preparing aLIGO IFO for pumpdown

 

SCHEDULE

MON  April 4, 2016  (possibly prior if time allowed)

1)    Transition to LASER SAFE

2)    Turn cleanrooms on around HAM6

3)    Mark and move ISCT6 out of the way to facilitate door removal

4)    Clean area, door flange, and cleanrooms

5)    Stage supplies and equipment

a)     Contamination control kit

b)    B&K hammer setup and computer

c)     Various ISI damper assemblies

d)    ISI tool kit, TMD table setup

e)     ISI parts as per E1600084

f)     Septum viewport cover D1200448

6)    Confirm dust monitor is working

7)    Lock HEPI

8)    Confirm purge air is on at HAM6

9)    Vent HAM6

 

TUES  April 5th, 2015

10)     Remove ALL 3 CHAMBER DOORS – Review and follow M1100039 “ Hanford checklist – HAM Door Removal”

11)     Entry chamber checklist items: Pick up floor CC wafers.  Take particle counter measurements and record:

12) SEI Lock ISI 

13) Entry chamber checklist items: Pick up table top CC wafers. 

14)Install Septum Window Cover

15) Evaluate, mark and Move Beam Diverter ONLY IF ABSOLUTELY NEEDED for ISI work.  IF CABLES of Beam Diverter get removed, a test of the Beam Diverter function will need to be made before closeout.

16)     Start ISI damper install work. 

a) ISI Wall units need to be moved for this work. 

Note, DO NOT REMOVE ANY TABLE TOP OPTICS.  Confer with Keita before hand if this is needed.

b) Remove Tuned Mass Dampers (TMDs)

c) Install new spring damper assemblies

d) Measure new spring modes using the B&K System

e) Retune TMDs with new info

f) Reinstall TMDs

 

WED  April 6th, 2016

17) Continue ISI damper install work.

18) Take particle measurements and record:

 

THUR  April 7th, 2016

19)  Finish ISI damper install work

20)  Check Beam Diverter functionality

21)  Quick check of ISI Balance and clean TF

22)  Remove Septum Window Cover

23)  Chamber closeout – perform applicable exit checklist tasks E1201035.

24)  Take particle count measurements and record:

25)  Replace 1 HAM6 door if possible

 

FRI,  April 8th, 2016

26)  Replace remaining HAM6 Doors

27)  Begin pump down

              28)  Reset ISCT6

 

BRS-2 Installation DAY 9: BRS-2 Tilt data during last nights earthquake

Michael, Krishna

There has been very little wind since we have had BRS-2 up and running so I'm posting some interesting data from the earthquake last night. The attached ASD plot, shows the spectra from the Mag 6.0 earthquake in Japan last night. The data set was about 10k secs and centered around peak of the earthquake.

The first blue line is the BRS-2 raw rX data showing the resonance at 7.6 mHz. The green line shows the BRS rX OUT from the filter banks. The third shows the ground seismometer's Y measurement showing the big peak at 50 mHz from the earthquake. Notice that there is absolutely no such signal in the BRS-2 output. This is because the acceleration coupling is very small as shown by the fourth line. Also, the real angular signal expected from the surface waves from this earthquake were not big enough to be resolved by BRS-2. We need a bigger earthquake to resolve the angular motion of the ground from them.

I've also attached the matlab code for this data set.

Monthly Env Data for 3IFO Storage

   These are the temperature and RH data for the 3IFO Desiccant Cabinet in the LVEA and the two Dry Boxes in the VPW. There were some temperature fluctuation during the month but the RH remained constant and very low.     

Pressures near CP3

Pressure profiles over 1 day and 60 day attached

Current pressures (Torr):

PT-243:  1.05e-9
PT-244:  1.35e-9
PT-210:  1.35e-9

Pressure spike on 60 day plot on March 18th at 6pm local time likely from opening GV 1, 5 on March 18th after beam manifold vent.

H1 Status: Friday AM: 1 April

1 April 2016

 

Site Activities: as of 15:26UTC (8:26PT)

• 15:45 JeffB - LVEA - 3IFO
• 15:53 JeffB - out of LVEA
• 15:20 Kirshna, Michael - EY BRS-2
• 15:20 Aiden, DaveB - EY Hartman testing code
• 15:38 Water delivery, going to EX first

Morning Meeting:

• Three Major Activities: April 4th-9th - PSL high power, HAM6 vent, TCS Rotation Stage Commissioning
• priority: PSL High Power Oscillator: Peter, Jason
• priority: HAM6 vent: ISI damping - blade spring dampers, flexure dampers, dampers GS13 3 horizontal-3vertical
• priority: TCS rotation stage
• Vent plan is posted in DCC, E1600092, and posted on white board in CR, currently -v2
• PSL shuttered out from the IFO during high power oscillator work
• for vent: all 3 doors on HAM6 need to come off
• late in HAM6 vent, ISC test of in-vacuum fast shutter
• LVEA will be laser safe
• gate valves to arms will be closed
• viewport protectors will be installed on the septum viewports during HAM6 work
• BRS-2 work will continue off and on as Kirshna and Michael are on-site
• OTHER parasitic work next week, as approved through Work Permits

Major Activities by day of the week:

Monday:

• vent prep, break bolts on all 3 HAM6 doors
• PSL shuttered out - high power work starts

Tuesday:

• HAM6 doors come off

Wed: ...

Coming Up:

• ER9 May 18th-29th, LHO only
• ER10 July-ish, getting ready for O2

Questions that came up:

• HAM6 HEPI locked this Friday or first thing Monday morning?  Need Commissioner feedback about weekend use of H1.

Pressures near CP3

6 am reading (torr) 

PT243 -  1.07 x 10-9
PT244 -  1.39 x 10-9 
PT210 -  1.40 x 10-9

Pressures near CP3

4 am reading (torr) 

PT243 -  1.08 x 10-9
PT244 -  1.42 x 10-9 
PT210 -  1.43 x 10-9

Pressures near CP3

2 am reading (torr) 

PT243 -  1.09 x 10-9
PT244 -  1.45 x 10-9 
PT210 -  1.45 x 10-9

Pressures near CP3

12 am reading (torr) 

PT243 -  1.12 x 10-9
PT244 -  1.48 x 10-9 
PT210 -  1.48 x 10-9

Pressures near CP3

10 pm reading (torr) 

PT243 -  1.13 x 10-9
PT244 -  1.50 x 10-9 
PT210 -  1.50 x 10-9

Note: time stamp of site overview different by two hours from Chandra's last entry yet same values 

My 8pm reading turned into 9:30 because I forgot to look at 8. But my alarm is set for midnight, so get some sleep!

Pressures near CP3

8 pm reading (torr) 

PT243 - 1.13 x 10-9 
PT244 - 1.50 x 10-9 
PT210 - 1.50 x 10-9

No magical success with centering spots on ITMs

Tonight I moved the power recycling cavity axis around to try to center the spots on the ITMs.  I was moving PR2 around, and the IFO's ASC followed me.  It was a pretty significant move - enough that we no longer had green hitting the transmission cameras at the vertex.  The carrier power recycling gain never really changed, but the sideband recycling gain decreased.  I couldn't seem to recover this, even by moving the input beam (IM3 and a little IM2), so I have to think more about this.

Anyhow, when I tried to increase the power from 12W to 15W, I saw the ~0.5Hz pitch oscillations that Sheila describes in alog 26367. In general, the ASC loops are stable, however as we saw last night, it's very hard to get any coherence right near this peak, so I can't say for sure that we don't have a loop issue. 

Big EQ in Japan, so we're calling it an early night.

BRS-2 Installation DAY 8: BRS-2 Tilt data

Michael, Krishna

Today, we changed some parameters which correct for pixel-level non-linearities in the CCD. This improved the noise in the BRS-2 output.

We also improved several error-handling features of the code and created the Status signal (the 4th channel going in to SEI), which is set to have the following states: Good (5V), Damping On (2V) and Bad (0V). In the near future, there will be several other more detailed states on the BRS model screen indicating the specific problem, if it is in a bad state, which will help debug the problem. Detailed documentation on this will be prepared soon. We also filled out some of the filter banks for processing the BRS-2 data and for tilt-subtraction. More on that in the future.

The first attachment shows the BRS-2-rX signal in comparison to the STS2-Y seismometer on the ground close to it. The data is converted in to displacement units and was measured with low wind speeds on the order of 2-3 mph. The next page shows the coherence between the sensors. The instrument is still drifting and settling, so the low-frequency noise will improve over time.

We noticed that there may have been some excess noise in BRS-2, especially at higher frequencies, due to aliasing from the high frequency spikes (30, 80 Hz). Therefore we lowered the software low-pass corner frequency from ~50 Hz to 10 Hz. This does introduce phase-loss at ~few Hz but since this sensor is primarily used at ~10-500 mHz, this shouldn't be a problem.

The second attachment shows the output of BRS-2 after the improved low-pass.

Pressures near CP3

6:00 pm reading (torr) 

PT243 - 1.11 x 10-9 
PT244 - 1.45 x 10-9 
PT210 - 1.45 x 10-9

summarizing csoft pit oscillation information

We have an oscillation in H1 that has been with us for a long time, is not understood, and can be mitigated by moving alignment offsets, and gets worse at high power.  All the information in this alog is elsewhere in the log, this is just a summary.

For about 6 months we didn't change our soft loop offsets because when we did we would get the oscillation, this is how we stayed stable through O1.  The main symptom is that the pitch optical levers move at frequencies around 0.45 Hz, all in phase with each other, and if you look at the relative sign of the optical levers it looks like CSOFT motion. the POP and arm transmitted powers also oscillate. Now that our soft loops are working again, we are probably in a position to again tune the soft loop offsets to be stable at 20 Watts, but it seems like this won't be a great solution as we try to increase the power even further. 

There have been many alogs about this, but I wanted to summarize some of the recent things we have looked at. 

It seems like the torque that moves the test masses isn't coming from any of the arm ASC loops, or the optical lever damping.  The first screenshot shows this, this is from Tuesday night when we powered up several times in slightly different configurations and repeatedly saw the same size of oscillation.    The solid lines here show what was our normal configuration before Tuesday, with ITM optical lever damping on and ETM optical lever damping off.  The dashed lines show the test configuration, where we added notches to the soft loops that reduce the actuation by about a factor of 100 at the oscillation frequency, and lowered the CHARD gains by a factor of 10. You can see that in the test configuration we also have about 5 and a half times less DHARD drive in the test configuration than in the normal one.  Since all of these ASC drives are smaller in the test configuration but the oscillation is about the same, it seems like the force that moves the test masses must not be from these control signals. 

It seems like the fluctuating radiation pressure due to changes in circulating power alone can't provide enough torque.

In the attached matlab script I estimated the miscentering we would need on each optic so that the approx 900 W changes in circulating power we see during the oscillation could provide the radiation pressure torque.  These are way too large, ranging from 8-33 cm on the different optics.  As a sanity check I also assumed that the alignment shift we see powering up before the soft loops get a changce to correct is due to radiation pressure (which it may not be).  From that I estimate miscenterings ranging from 0.5-3 cm. I used the moment of interias from Evan Hall's alog , which he tells me are slightly wrong but not enough to matter.

The oscillation frequency does seem to depend on circulating power

The evidence for this may be a little shaky since it is hard to get enough cycles of the oscillation to get a spectrum with nice resolution, but the second attached screen shot shows a spectrum of ETMX optical lever pit for 3 different circulating powers.  These circulating powers are based on Dan Hoak's calibration and the TR XB QPD.  The frequency of the lower two powers is the same within the resolution of my spectra. This may not hang together perfectly because I have included a little bit of time when we were powering up or down in the spectrum.

frequency	circulating power	time
0.44	23.6kW	30/03/2016 03:53:05
0.44	34.3 kW	30/03/2016 03:53:38
0.515	52.9 kW	31/03/2016 04:13:30

Other ideas?

We have also tried putting a resonant gain the DARM loop(no impact), changing A2L feedforward (no impact), and centering on the ETMs (improvement).  One possible test we could try to understand this better would be to drive the laser intensity and see if we can produce angular motion.  

ASC better with non-broken QPD

We've had much more success tonight with the non-broken Xarm Trans QPD.  We once again re-centered the spots on the ETMs, although they didn't need much moving.  We are able to sit at 10W and 12W just fine now.  Now, we're running into regular ol' loop oscillations, so we've been measuring loops at different powers, and trying to re-tune them. 

CHARD Y seemed the most egregious, so we created a new control and boost filter combo, which live in FMs 4 and 5.  Unfortunately, these filters are totally unuseable at 2W, although they improve our stability at 10W, so right now the guardian still only engages the old loop shape filters.  We'll have to re-think the 2W filter situation to make sure we can transition between these filters.  Right now, we were by-hand turning off the CHARDY loop, changing the filters, then re-engaging the loop.  Attached is an open loop gain for the new loop.

PRC2 pitch we've decided is kind of okay if we use a factor of 2 less gain.

Now, we're seeing oscillations that also show up in AS 90, so we suspect either the MICH or SRC angular loops.  Unfortunately, there's something going on with NDS/the lockloss plotter/something, such that I can't get data from the last ~5 locklosses.  The ones before that, I can still get and plot, but it can't find data for the last several even if it's been an hour since that lockloss. 

So, next up:  Measure the MICH and SRC loops at 10W to see if they're close to unstable.  Measure again at 15W, and then think about going from there.

I feel I should know this already, but what is known about the QPD failure (circumstance at failure, failure mode, etc.)

I am designing the input circuitry for the ITM PI Driver using the same input chip as that used on the ETM PI AA, so I will hedge our bets by including some input protection circuitry (current limit and clamp) to avoid this if that turns out to be the case.

Daniel is correct.  The chips used on the input to the PI filters have internal input protection diodes that will (up to the limit of their current handling capacity, which is not much over 10mA or so) clamp the voltage from the QPD amplifier to something around a volt.

This is not a problem if the PI BPF is powered, which is the normal state of the system.  This event prompted a redesign of the differential input to the ITM ESD Driver to avoid this in the future.  Another case of incremental learning.

List of Front-end Model Updates Today; Work (though hopefully univasive) will continue into Tomorrow

J. Kissel, B. Weaver, H. Radkins, D. Barker, J. Batch

Here's a list of all of the upgrades we were involved in today. There will be more details of the upgrade, more debugging, associated MEDM screen changes, svn commits, and other clean up tomorrow as we continue to explore what we've installed and debug. Bear with us, and thanks for your patience.

1) Fixed UIM coil driver path's automatic compensation bug by updating CD_STATE_MACHINE.c. See Int. Issue 1178.
2) Installed ISI GS13's projection to SUSPOINT Euler basis projection into the SEI models. See ECR E1600028.
3) Sent the Euler Basis Longitudinal DOF for each SUS involved in a cavity over various IPC (PCIE and RFM) and models (ISI, End-station PEM, H1OAF) to be collected in OAF. See ECR E1600028.
8) Removed the excess RFM channels from End-Station ALS models (noteably *not* the excess channels in the ISC models). This made room for 3). See LHO aLOG 25216
4) Added various rotational sensor correction paths to the BSC ISIs (GND BRS to ST1, and ST1 to ST2). (Prototyping, this stuff, no ECRs just yet)
5) Removed the L4C sensor correction path. See SEI aLOG 666
6) Added new infrastructure for the EY BRS. (Most Copied from EX, covered by ECR E1500246)
7) Reverted the BSC SUS's coil driver monitors to store the NOISEMON in the frames (and pushed the FASTIMON to the commissioning frames). Also, we put filter modules in front of the NOISEMONs (like was done for the FASTIMONs the last time we touched this) in case we ever wish to calibrate them. See ECR E1600033 and LHO aLOG 26313

Because we haven't built MEDM screens and actually *used* any of these paths yet, there's still potential for bugs and we haven't explored and/or fixed all of the collateral damage. Stay tuned as we continue to work on all of these updates tomorrow.

J. Kissel

I've documented all of the front-end model changes that were necessary for items 2, 3, 5, 6, and 7 (i.e. all of the SEI model changes). Check out G1600795.

As indicated in LHO aLOG 26321, all of the simulink model changes have been committed to the repository.

J. Kissel, H. Radkins

Here're the updated MEDM screens that correspond to the above SEI model updates.

I'll work on the Cavity Basis OAF MEDM screen tomorrow.


The following screens where changed and/or added:
/opt/rtcds/userapps/release/isi/common/medm/bscisi
A         ISI_CUST_CHAMBER_ST1_ROT_SENSCOR_FIR_ALL.adl
A         ISI_CUST_CHAMBER_ST1_ROT_SENSCOR_IIRHP_ALL.adl
A         ISI_CUST_CHAMBER_ST1_ROT_SENSCOR_MATCH_ALL.adl
A         ISI_CUST_CHAMBER_ST2_ROT_SENSCOR_FIR_ALL.adl
A         ISI_CUST_CHAMBER_ST2_ROT_SENSCOR_IIRHP_ALL.adl
A         ISI_CUST_CHAMBER_ST2_ROT_SENSCOR_MATCH_ALL.adl
Sending        ISI_CUST_CHAMBER_ST1_SENSCOR_OVERVIEW.adl
Sending        ISI_CUST_CHAMBER_ST2_SENSCOR_OVERVIEW.adl
Sending        ISI_CUST_CHAMBER_OVERVIEW.adl=

CC gauge at CP8 won't start

Reset a few times, but won't turn on.

This gauge was cycled as the result of a CDS reboot.