kyle.ryan@LIGO.ORG - posted 15:37, Tuesday 26 August 2014 - last comment - 16:53, Tuesday 26 August 2014(13606)
~1525 hrs. local -> Valved-in IP11 @ Y-end, Valved-out turbo
At request of Borja
At request of Borja
S. Karki, Dave Barker Troubleshooting low freq Mic at ENDY and CS: 1. The power to the DAQ (sitting on top of each microphone) was reset by pugging off the power supply cable and plugging it back in. 2. The signal cable were switched to a known working channel. Both resulted in no difference to the signal output suggesting that the microphone itself could have been damaged. The signal from the mic seemed to have stopped since the last power glitch.
Switching from the currently used CS microphone to the extra one sitting on the floor solved the problem, suggesting that microphone is bad.
Removed the Ring Heater Assembly from the ITMy quad structure going into 3IFO storage. Before starting I noticed the lower ring heater assembly had a crack in the glass former. Not sure when the break happened, but this one also displayed a lot of movement inside the ring heater shield. The pictures show how the former has pushed pretty far out of position. The ring heater cables were also removed. This includes the "antlers" (D1001755) but not the plate (D1002420) which the earthquake stop is attached to. The assemblies removed were: ASSY-D1001895-V5 #001 (lower ring heater, broken) ASSY-D1001517-V7 #612 (cable assembly) ASSY-D1001838-V6 #005 (upper ring heater)
That should read ITMx (not y) and ASSY-D1001838-V6 #002 (upper ring heater) not #005. typos.
Note, when the 40kg optics are installed and removed from the QUAD lower structures that these ring heaters are mounted to, there is some torquing of the structure (and therefore the RH). Possibly this adds to these failure modes.
One more fix. The lower ring heater should be: ASSY-D100195-108 Made a mistake with a V5 and V6 part.
This last occurred at EndY 5 Aug but it wasn't restarted until 11 August. So barely 24 hours later it dropped out again. 14 August was the power outage and it appears no restart attempt was made at EndY. EndX is running at this time. Borja is taking data at the moment and asks the optic not be disturbed. This restart will require a trip to the EndY MR.
Dave just reminded me of the power glitch at 2355utc 12 August and this is when the pump stopped. I can see that EndX also saw the glitch but appears to ride it out and was quickly restarted after the power outage. All assumptions as I've found no logs about HEPI restarts before or after the power outage.
Filiberto, Kiwamu (WP4816)
We have installed three analog cameras that are going to monitor the signal-recycling mirrors (i.e. SR2, SR3 and SRM) on HAM4 and HAM5. We put a good TV lens on each of them and adjusted the aperture and focus.
The detailed location of the cameras are described in the viewport final design document (page 54 and 55 in DCC-T1000746-v7) and we followed it.
no restarts reported.
Maintenance: Reset HEPI overflow counters for HAM2, HAM3, HAM4, HAM5, ITMX, and ITMY
Attendees: Gerardo, Filiberto, Keita, Koji, Kiwamu, Jim, Jeff B, Ed, Peter, Justin, Aaron, etc … Today's Tasks: • Viewports installation on HAM6 – Gerardo • Running power cables for illuminators and analog cameras in LVEA – Filiberto • SR3 Optical Lever work continues in LVEA - Jason • Cameras installation on SR2, SR3, and SRM (LVEA) - Filiberto • Dust monitor work in LVEA – Jeff B • ISC table to be moved (LVEA) – Keita • Cable pulling all around the LVEA – Aaron • Moving 3IFO (Quad#8) to its proper location in LVEA – Jeff B
The performance of the intensity stabilisation servo (ISS) will not be measured this week due to some problems with the servo. I am not sure what the cause of the problems are but the servo has problems locking. The diffracted power as indicated in the MEDM screen, switches between two states, regardless of whether the servo is attempts to lock in either automatic or manual mode. The relative power noise measurement is close to the reference measurement. It is slightly better below 10 Hz and slightly better above ~5 kHz. Both are well within the requirement for the laser. Both the control and error signals in the frequency noise measurement are better than the reference measurement. The error signal looks strange below about 60 Hz with a number of steps present. The beam pointing measurement is not as good as the last one performed on August 12th, with the 1x and 1y error signals being a factor of 3 higher. The control signal in both cases is about the same as the previous measurement. The power incident on the reflection photodiode is about the same. The mode scan does not look all that different from the previous two scan measurements. The relative peak heights look the same to the eye. The higher mode content has increased by 2%, with the higher order mode power increasing by 0.2%. The cavity finesse is the same within the errors.
I checked the Crystal Chiller this morning. The water level was fine.
Borja
Yesterday's results in ETMX although positive from aLIGO operation point of view (no charging mechanism was observed based on green light and ion pump) however it was discouraging from the point of view of providing answers to the big charge changes that were observed in ETMY. If the ion pump was not charging the mass then what was doing it? Is this unexplained behaviour in ETMY charge changes casting a shadow over the charge measurements methodology? Fortunately a new set of measurements in ETMY that were taken during the experiments at ETMX confirms that the measurement method is reliable and it also tells us what is charging ETMY. For a period of 62 hours 6 charge measurements were taken on ETMY, for all these measurements the ion pump gate valve was closed. The results are remarkable in their consistency and stationarity of the charge values for all quadrants and for both orientations (pitch and yaw) within no more than 20Volts (less depending on the quadrant and orientation). The charge values agree with the last measurement taken just before closing the ion pump gate valve.
The amount of measurements make it impractical to show a summary table like in my previous aLog so this time I go for a more friendly graphical display. As always attached are the measurement documents and the standard VBIAS vs normalised deflection plots comparing each measurement with the ion pump gate valve closed with the first one, and the first one with the one previous to closing the valve.
So what is different between X and Y regarding the charging effect of the ion pump? mainly 3 differences:
1) The Earth magnetic field
2) The pressure being different by an order of magnitude. The pressure in end-X is 2.7e-7 torr while in end-Y is 4.8e-8 torr. A higher preasure will reduce movement of the ions, but at the same time the higher the pressure the more charge is emitted by the ion pump (see attached document "charged_particle_emiss_ion_pumps.pdf").
3) Both ion pumps were costume made to the same specifications. They are made of 50 smaller ion pumps so maybe the way these were configured is different for each final ion pump.
Next I show the summary plots of all measurements taken so far both for ETMX and ETMY. Each mass has 2 set of plots; Veff and slope of normalised deflection vs VBIAS. Each set of plot is divided in 2 subplots, one per deflection orientation (pitch and yaw).
ETMX:
ETMY:
The numbers in the plots represent the major changes that took place at the time of the measurements. These are summarised next:
1) 1st ionizer discharge.
2) 2nd ionizer discharge.
3) Wire swap to right configuration: BIAS going through the ESD LP filter box.
4) Wire swap to wrong configuration: LL quadrant driver going through the ESD LP filter box.
5) Wire swap to right configuration and Final: BIAS going through the ESD LP filter box.
I'm not sure if this plays a roll in this study, but for the record the ETMx, ITMx, and ITMy test masses and reaction masses had the long ~9 minute deionozation blow off before chamber close out earlier this month. The ETMy and it's reaction mass did not because it was not opened for this vent. The ETMy only had the quick ~1-2 minute blow off when the First Contact was pulled from it's surfaces earlier in the year. As well, the ERMy FC was pulled many weeks before the ETMy FC was pulled, so these short deionization blow offs were also widely separated in time.
I saw the measurement status indicator blinking in the SRM screen, but no excitations. According to trend, this has been on all the time in the past three or four days. So I assumed that this is something Arnaud forgot to turn off and therefore I switched it off.
I have spent some time today trying to get decent interferometer alignment.
The goal today was to get good PRMI alignment while maintaning the POP beam at ISCT1. I could obtain good alignment only in pitch. The yaw alignment still needs to be touched up.
(background)
Even though we managed to get the POP beam extracted at ISCT1 (see alog 13547), this resulted in bad alignment in the PRMI. We basically could not flash the PRMI without loosing the POP beam if we touch a single optic to align the PRMI. So a combination of some optics needed to be touched up.
(What I did)
Since the Michelson had been already (kind of) aligned, I assumed that ITMX is well-aligned. Also, I assumed PRM and IM4 to be already aligned (this may not be true -- I should have carefully checked IM4 and perhaps other IMs). Under these assumptions, I tried to aligning PRX. Note that I misaligned ITMY and BS during the process. I touched PR3 and PR2 in pitch to find an optimum alignment. Doing some iteration, I got a good alignment. The attached is the resultant alignment. This alignment maintains all the signal ports including REFL, POP and AS. However, since only pitch is optimized, this configuration does not allow the PRMI to flash yet. In order to flash the PRMI, one needs to steer yaw of some optics. For example, one can change yaw of PR2 from 3640 urad to 2179 urad to flash the PRMI. No pitch adjustment is required.
Also, I tried the same iteration process in yaw. But this did not seem successful for some reason. As I aligned the combination of PR2 and PR3, it seemed that the beam started hitting the right hand side of the PR3 cage. And indeed the amplitude of the demodulated signals decreased at REFL. The work continues.
~1610 hrs. local -> Began pumping HAM5/6 annulus
model restarts logged for Sun 24/Aug/2014
2014_08_24 06:26 h1fw1
unexpected restart of h1fw1
I locked and unlocked the ISI to confirm it's position shift remains in spec, it does. While locked, I unbolted three of the 10kg masses and set them on three 1/2x1/2x1/8" viton. The position on these damped masses is on the as-built redline I have added to the D1201388 DCC record.
0845 - HAM6 close-out work. Hugh, Kiwamu and Keita verifying all cables properly grounded and doing final survey for class B tools and parts
900 - LVEA transitioned to laser SAFE by Keita/Kiwamu for door hanging and crane work.
1000 - Kyle, Gerardo prepping for hanging N, S doors on HAM 6. Removing viewport emulator.
1011 - Jason working on SR3 oplev
1030 - Besty working in West Bay LVEA
1038 - Christina/Sudarshan working at EX
1225 - Patrtick working on Conlog...system offline
1250 - Conlog recovered
1310 - Doors going on HAM 6
yesterday we noticed that ITMX has been tripping, it seems to happen within a minute or so of becoming fully isolated. HEPI seems to have position loops running, there is no feedback from ISC to the suspension or HEPI. The last few trips have been just stage 2, actuator trips. It looks like something is ringing up.
The stage 2 blends were on Tbetter expect RZ, which was on Tcrappy for the two trips plotted in the first screenshot attached. I've tried setting stage 2 blends to start, this also caused a trip which is the second attached screenshot.
Now I have set the guardian to isolated_damped, so that stage 1 is isolated and stage 2 is damped. So far its not tripped.
For the last 20 minutes or so, stage 2 has been isolated level 1 with no problems.
It seems that the level 3 controllers for X are the problem. It was fine with stage 2 on level one controllers, and it stayed isolated with all DOFs other than X at level 3. It tripped even when I used no boost for X.
From looking at the trends it seems as though the ITMX ISI hasn't really been isolated since the first week of june. Jeff suggests that the problem could be that the plant has changed durring the vent, and now the controllers designed before the vent aren't stable (for X). Here is a screen shot of a spectrum just before one of these trips. The problem seems to be at 147 Hz. The filter is also plotted here, with the cursor at 147 Hz.
Hugh also reported a problem on August 8th, at 320 Hz. (alog 13294 )
It looks like this loop needs some TLC. For now I'm leaving the guardian at ISOLATED_DAMPED, but it can be semi isolated by going to the command scripts, and turning on the level three controller for all DOFs except X.
I worked on these loops a bit this morning. I ended up adding a notch in the ST2 X isolation loop at 147, and now everything turns on. I wouldn't say everything is happy, as the drives are still quite high, so it would be good to get an in-vac tf and re-visit the loop design. It's been running for the last 20 minutes or so. Will talk to commissioners about a convenient time to do further work on this.
Thanks a lot Kyle for the very quick response.