1455 - 1520 hrs local -> To and from Y-mid Exhaust check-valve bypass opened, LLCV bypass valve opened 1/2 turn -> LN2 at exhaust in 55 seconds -> Restored valves to as found state. Next CP3 Over-fill to be in < 72 hours.
Jeff B. informed us this morning that he had to add 400mL of water to the PSL crystal chiller, while last night it was fine. Doing a humdity trend of the HPO box showed a sharp spike, indicating a possible water leak. We immediately shut down the laser and chillers and went out to investigate. Upon opening the HPO box we saw water covering the floor of the box and dripping out of the connection from the head 1 ASE dump to the head 1 flow meter (Hose_as_found_20160420.jpg); the hose had failed, causing a major water leak (in the picture you can see where the red covering ripped away due to the water pressure). We mopped up all the water we could, drained the laser head water circuit, and removed the failed hose connection (Hose_failure_closeup_20160420.jpg). Luckily the hose was long enough that all we had to do was cut off the failed portion and reattach the hose. I took the failed section and removed the red outer covering and found a small hole in the silicon in what looks to be the area where the hose seals on the fitting (Hose_failure_point_20160420.jpg). I think that the repeated loosening and tightening of this connection we have had to do over the last week, probably combined with the age of the hose, weakened the hose at this point causing its eventual failure.
We performed a preliminary inspection of the optics and it appears we may have lucked out; no water is visible on the surface of any of the optics in the HPO box. We are currently letting the HEPA fans and the AC run for a copule hours to dry the HPO box out completely, and will then do a more thorough inspection of the optic surfaces of the HPO.
Filed FRS 5318.
Went in after lunch and inspected the optic surfaces with a green flashlight. Everything looked good, no water spots. Started up the chiller and after several minutes did not observe a water leak. The inside of the HPO box is still wet, so we are leaving the fans and AC running overnight to continue to dry it out. While this is happening the laser is being left OFF. We will go in and assess everything in the morning, and bring the laser back up if all is in good health.
I think Jason meant "assess".
Good catch, thanks Peter. Fixed.
A BSC-ISI model update about a month ago changed the St1-2 feedforward and sensor correction infrastructure. Before, there were independent feedforward and sensor correction paths, each receiving both L4C and T240 signals, meaning each sensor was getting sent twice. Now, there is a single path that gets shared to both the St1-2 feed forward and sensor correction banks, which means if we want to do both sensor correction and feedforward, we need a blend filter. For now, I've cannibalized the Quite_90 filters to do this, but it's likely this will need some more thought.
What I've done for now is taken the Quite_90 high pass (the L4C component) and used the relationship (low_pass) + (high_pass) =1 to design a complementary low pass filter. I started by taking the Quite_90 high pass and multiplying it by the L4C response to get it in a complementary form. In addition, the blend filters do the integration of the seismometer signals, which I don't need, so I had to multiply the high pass by a zero at 0 to convert it from (nm)/(nm/s) to (nm/s)/(nm/s). The complementary low pass is then just 1 - (high pass).
My first plot compares the resulting filters with the originals, where green (FFB L4C) and blue (FFB T240) are the Feedfoward blend filters and brown (Quite 90 L4C) and red (Quite 90 T240) are the St1 blend filters.
The second plot shows the complementarity of the FFB filters, showing that (low_pass) + (high_pass) =1. The final high pass then needed the L4C inversion added back in, to account for the L4C's frequency response.
The third plot shows how accurately the blend filters sum the two signals. To check, I looked at the St1 T240 signal (solid lines), and compared that to ST2 FIR IN (dashed), which gets the output of the blend banks. For this measurement, I turned off all feedforward and sensor correction to ST2.
-The red traces are with the FFB blends turned on, so the dashed red line is the blended sum of the L4C and T240 signal. Seems pretty good.
-The blue line is with the FFB blends turned off, but the inputs and outputs turned on, so the dashed blue is just the sum of the L4C and T240 signals. Compare this to the solid blue, you can see this is clearly wrong above a hz. Below a hz the L4C acts like it's own high pass, so it doesn't contribute much here, as you'll see soon.
-The green traces are with the L4C alone. Remember, the solid line is the T240, but in this case, the dashed line is just the L4C. The response below 1 hz is low, because this motion is below the L4C's resonance, so the L4C is less sensitive to motion at these frequencies. This is why blends invert sensor responses.
The fourth plot shows the St1 T240 & St2 GS13 performance on ETMX in Z, the only dof where I'm currently running both feedforward and sensor correction. The red traces are with St1-2 FF and SC on, the brown traces are off. Again, seems to work like it should. The fifth plot is the suppression (the ratio of St2 motion to ST1) for the on and off configurations.
While I was taking these measurements, I realized that the St1 performance is limited by T240 sensing noise at around 1-3 hz, see my last plot. I don't know if we can do anything about it, but it's interesting.
These filters are now installed and running on all BSCs, on all dofs. This has been captured in the appropriate snaps, as well.
Now that X-mid has been upgraded to Beckhoff, transducer read back values which exceed 100% are displayed as 100%. I found this to be an important detail when trying to interpret why CP6's level wasn't shown as reducing as a function of time with the stated conditions.
1330 hrs. local -> Magnehelic between 43" and 44"? No change? Also, I briefly valved-out the instrument air to the LLCV actuator and perceived no valve stem stroke, i.e. the current manual setting of 5.00% open is the same as if 0.00% open.
The IM alignment shifts have caused locking issues, and so I asked TJ to add an alignment notification for IM1, IM2, and IM3 in DIAG_MAIN.
I've set the notification levels at:
These levels reflect roughly twice the drift in a recent 60 day trend.
Nominal alignment values in the notifications are:
IM3 yaw nominal value may need to be updated in about a month, since it has a sustained downward drift that was present through O1 and continues.
- TJ, Cheryl
To clarify:
Limits on alignment shifts:
Limits on alignment Notifications must be larger:
The Notifications are only intended to allert Operators and Commissioners to an IM alignment shift that may have happened during a time when the CR was not staffed.
What is always true regarding the IM alignments:
When HAM2 ISI trips, it continues to be necessary to trend IM1, IM2, and IM3 alignments to check for shifts that need to be corrected, regardless of the Notifications appearance or lack of appearance on DIAG_MAIN.
Set H0:VAC-MX_CP5_LIC300_LLCV_POS_CTRL_PCT_DEAD_BAND and H0:VAC-MX_CP6_LIC350_LLCV_POS_CTRL_PCT_DEAD_BAND to 0.5.
We seem to have 2-3 times the amount of light into the fiber and available at the end stations. The photodiode measuring the light after the reference cavity and Faraday is saturated and needs a factor of 2 attenuation.
The RF max limits were increased by 2dB on the discriminators. The RF crystal frequencies are about 120MHz lower than before. Around -110MHz and -180MHz in X and Y, respectively. Before they were around 0MHz and -60MHz. Both ALS end station PLLs are locked.
Updated the web page displaying vacuum screen detail to use the correct MEDM screen for MX vacuum detail.
Killed old Met One 227b IOC, started new Met One gt521s IOC for diode room. Dust monitor still needs to be connected properly and powered up.
This fixed the communication error.
CDS - Continue vac upgrade, also swap in mech room.
Vac - stuck cryo valve at MX
Facilites - Landscapers spraying, timbleweed cleanup. Fans are greased, but swaping out some filters.
PSL - Laser is working but some things aren't working as they should.
Work permits reviewed. Safety meeting most likely.
TITLE: 04/20 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
Wind: 5mph Gusts, 2mph 5min avg
Primary useism: 0.02 μm/s
Secondary useism: 0.17 μm/s
QUICK SUMMARY: IMC is locked, ITMX ISI tripped most likely from a handful of large earthquakes in the past 6 hours.
(Foggy memory) I think, the manual settings for CP5, CP6 and CP7 are currently lower than needed to maintain pump levels (more like 80%, 60% and 80% respectively?).
Chandra is contacting Dave to see if they can be changed from offsite.
Kyle - yes on those values. I trended the data over 30 days. Manual values were set very low. I am at the lab. I've been simulating a PID with manual control of valve opening while watching real time trends. I manually filled CP5 as soon as I got here. Took about 19 min. to get to 100%. Then I adjusted valve settings in control room and decided to manually fill CP6 because it was dropping to below 85% (after raising valve level to 65%). I turned bypass valve half turn (with bypass exhaust valve open). The bypass LLCV is stuck open! I cannot close it. So I currently have the LLCV set to 0% and the bypass exhaust valve open. Pressure reads 0.0 psi. I'm waiting and hoping the liquid level falls below 100%. I'm not sure how 1/2 turn equates to LLCV percentages.
I went back out to CP6. When bypass exhaust valve is closed, pressure reads 0.7 psi. I left it half way open. Pressure reads 0.1 psi. Level is still 100%+ with LLCV bypass valve stuck 1/2 turn open. I am guessing it is frozen open. The pipes there are really cold. Exhaust pipes are frosty.
Chandra - you're kind of weird chick - I like you. We can now deal with this in the morning! Keep in mind that we have past data to suggest that 60% full doesn't translate into off-gassing and that the pumps boil-off at ~2.5%/hour when LN2 flow is stopped altogether so we don't need to go full "Kyle" just yet. Still, it i comforting to know that someone else is "sick" with worry about getting caught off guard regarding the 80K pumps!
I am breaking records for trips to CP6 in one night. Bad idea to partially close bypass exhaust valve. Lots of N2 vapor and liquid started pouring out both ends (pressure is ok). So I closed the main Dewar valve. Then I opened it just a half turn. Back to liquid and vapor pouring. So it's now fully closed. *Everything* is cold so I think the system will be safe until crew arrives in morning to try to thaw bypass LLCV. -Oh, just read your data, Kyle. Great! 2.5%/hr loss when main valve is closed tells me I can go home to bed!
09:00 local time. I drove out to MIDX to check on the frozen valve. It is now free as the transfer line has warmed up overnight.
I left the dewar shutoff in the closed position and will leave it there until the CP6 level falls below 100%.
