FRS7394

Hugh, Dave:

We replaced the last calls to perl scripts (wd_dackill_reset.pl) with direct PV access. I think we have now completely decommissioned perl scripts from IFO operations.

I looked at a couple times when power into the IMC was increased, and the power change shows up on sensors, specifically IO GigE 2 (IMC_IN), IMC-WFS_A_DC_PIT, and IM4_TRANS_YAW. The IMC mirror alignment and PZT also respond.  Plots attached are 1) power to 10W, 2) power to 27W, both with sensors, and 3) power to 27W showing IMC mirror alignment.

  Inspected the foam sealant around the 7 cable ports (two between the Enclosure and the Anti-room, and five between the laser room and the LVEA) in the PSL laser room. A couple of the ports had almost no foam sealant installed, and in a few other ports the foam sealant had fallen out.

  Installed, replaced, and renewed the foam sealant around all 7 cable ports in the PSL enclosure. The laser room is now much better sealed. This should increase positive pressure inside the laser room by a small amount.   

WP 7784

I have updated the PLC code for the remote control of the motorized fiber polarization controller to help deal with the fact that it does not save the position of the paddles between power cycles if those positions are set through the remote interface. There is now a 'Restore' button next to the power buttons on the medm screen. This will set the positions of each of the paddles to their last read position. The intention is for this button to be clicked after the power is turned back on to move the positions of the paddles to what they were before the power was turned off.

seed/pump Co-resonance temperature set to 41 C. Double checked with seed transmission scan using the homodyne. The manual flipper weren't flipped up before LVEA went laser safe so we have no camera to look at the transmitted seed beam.

Pump laser has to be taken off PSL due to an on-going work that would trip off the laser locking constantly. Cranked up OPO common path gain to 0 to tighten the loop a bit. This left us with 13 deg phase margin. So much for that idea. High peak around UGF. Back to -18dB as usual.

I also went out and unplugged the fast PZT output from TTFSS as it produces 232 Hz harmonics when TTFSS is not locked so the PZT doesn't get overdriven. Forgot to post an alog about this investigation.

Seed fluctuates a lot. At least 40% fluctuation or so.

    The skies look clearer and the smoke haze, with the help from some nice winds, has been somewhat reduced. The current map (www.airnow.gov) shows our air quality in the moderate category. There are large areas of unhealthy air to our west and north. Wind direction over the next couple of days will influence our local air quality. If you are concerned about the air quality; or are feeling the effects of the current conditions, please consult your physician or contact site safety.

08:00 Particle Counts

The LVEA has transitioned to LASER SAFE.

    This is to facilitate vacuum work

    The TCSX CO2 laser has been switched off.  The TCSY CO2 laser is to remain off during this period.

    This transition is under work permit 7785.

Hang, Sheila, Stefan

We closed some more WFS loops:

A) MICH_P/MICH_Y loop:
 - We phased and compared the AS_A_36 against the 72 signals. Since the AS_A_36 had a cleaner error signal, we decided to use AS_A_36_Q for the BS for now. That loop is now engaged at the beginning of the CARM reduction sequence, and never turned off.
 - Also, so far we drive DHARD to ETMs only. We will have to enable the ITM feed-back as well.
 - We also turned on INP1 (gain -1) and PRC2 (gain 500). PRC2 slightly draws down the recycling gain at the moment, but closes just fine.
 - Next we closed CHARD with low gain (engaged at 0.03, then increased to 0.3). But when we tried the +46dB we got a gain oscillation in pitch. SO for now we stay at low gain in CHARD.  

 - We tried to put all of that in Guardian (REFL_POP_WFS), but the PRC2 and CHARD engagement gave us some problems. So for now Guardian doesn't engage PRC2/CHARD.

We have seen one of our bounce modes, which we hadn't seen until today since the installation of the bounce mode dampers.  

The mode we see is at 9.726Hz, and seems to be ITMX.  

Jim W suggested that ITMX might be the problem since the suspension was left damped overnight while the ISI was isolated, which we know causes problems.  I tried the same phase as the O2 damping: -90 degrees, gain of 1

Originally from alog 30737:

ezcareadpast:
=============

From the shell command line:

ezcareadpast.py H1:ASC-PRC1_Y_GAIN 1161131166
 

Or in pyhton:

import ezcareadpast as e
value=e.ezcareadpast('H1:ASC-PRC1_Y_GAIN',1161131166)


wfsreliefpast:
==============

Set all optic to the alignment they had at the specified GPS time - uses both alignment and top stage output:

wfsreliefpast.py 116114000



Both scripts are available in /opt/rtcds/userapps/release/asc/h1/scripts/, as well as in /opt/rtcds/userapps/release/isc/h1/scripts/.
They are also made available globally through a soft link in /ligo/cds/userscripts.

I took the TF of the OPO TEC Loop, with the plot attached below.

The blue curve is the original loop, with UGF @30mHz, and a phase margin of ~44deg.

I increased the gain by a factor of 1.9, making the Gain = 1.33 in the LOOP SHAPE manual in MEDM. (Other filters unchanged)

Now we have a UGF@50mHz, and a phase margin of 50deg. This should make the loop more stable and faster. (Red curve.)

For the SHG, the loop looks good enough with UGF @25mHz, and phase margin ~50deg.

Notes on how to take the loop TF:

OPO/SHG TEC servo screen --> little screen under Excitation

Set the frequency and amplitude (10E-3V worked well) --> Switch on --> Click reset

You will need to integrate for a good while until the number stops fluctuating.

If you change the frequency or amplitude, you need to hit reset.

We should make sure these excitations are off after taking the measurements.

Peter, Fil, Jason, TJ, TVo

We started the day thinking the laser head could be the issue, but once we swapped the cables and plumbing to a brand new laser, it didn't solve our problem of not being able to lase.  Peter found that if he wiggled and loosened an RF cable that goes from the Sine-to-Square wave comparator box to the 4-way splitter box, then we start to actually lase intermittently.  This confused us for a while and we decided to inject our own square wave with a function generator and bypass the comparator box, with 0-5V peak to peak @ 40.68 MHz and it started lasing at 55 Watts.  Then we added the comparator box and it still worked using our own source. 

This lead us further upstream towards the RF distribution box D1000124 and found that there was a bad cable.  The comparator box is expecting at least 4-5 volts peak to peak but was only getting approximately 40mV.  This fooled us because it looked like a decently shaped RF signal and we thought it was OK, but the power was all wrong.  Once we replaced the cable, it worked pretty well.

Tomorrow we'll replace the plumbing and cabling to make sure the old laser and old RF driver still works and return the spare laser and RF driver to storage, so we're not fully out of the woodwork but I think we found a big missing puzzle piece and we have at least one laser that works.  Not sure why this cable went bad all of a sudden.

It's been pretty windy all afternoon, but the last hour or two it's a teeny bit more windy than it had been, and we've struggled to hold ALS lock (green arms are okay, but locking to the PSL is not okay).  So, I changed the ISI Config guardian to MORE_WINDY at about 18:05 Pacific (01:05 UTC). 

At the same time, I did an initial alignment (just in case).  Between these 2 changes, and the wind is a teeny bit better again, we're holding lock a little better. 

Edgard B.

Following up on LHO:43512 and LHO:43513, I continued gathering transfer functions for designing QUADs the full Length-Pitch ISIFF filter.

I took almost all of the transfer functions needed for the ISIFF in every single QUAD.The only pair missing are M0 drive P in ETMY and ITMY. 

_________________________________________________________________________________________

All of the templates+measurements are saved with date of Aug 19 in:

/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/[]/Common/Data/
   2018-08-19_H1SUS[]_M0_ISIFF_FilterDesign_ST2L_M0_TF.xml
   2018-08-19_H1SUS[]_M0_ISIFF_FilterDesign_ST2L_M0_TF.xml

Where [] is either ITMY, ETMY, ITMX or ETMX.

Summary: Previously we detected no contamination of ADC channels by fans or from magnetic fields from the on-board power supply, but saw drifting lines. After powering I/O and AA chassis with linear supplies, the drifting lines were much reduced. There are three remaining more subtle issues: 1) Coherence between blank ADC channels in a 0.94 Hz comb, produced by a flashing LED that indicates link state, 2) A 1.000 Hz comb in the duotone channel that is coherent with some blank ADC channels, 3) An occasional drifting line, that produces coherence between blank channels, suggesting a rouge oscillator in the AA or I/O chassis.

A previous log noted that the new I/O chassis has much lower contamination from fans and power supply magnetic fields than previously tested I/O chassis, but that there were drifting intermodulation peaks, possibly associated with the 24V power from a Sorenson switching power supply ( https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=42907 ).

During the DetChar f2f, we powered the I/O chassis with a linear supply and found that the drifting peak features were mostly gone. I have since been looking into more subtle features in the blank channels of the I/O chassis. Figure 1 shows that the blank channel spectra are smoother (no evidence of drifting peaks) and the coherence between channels is significantly less than it was before replacement of the 24V switching supply (compare Figure 1 to https://alog.ligo-wa.caltech.edu/aLOG/uploads/42907_20180715170051_Figure4-CoherenceBetweenEmptyADCChannels.pdf ). But Figure 1 also shows that there are features associated with LED flashes.

The odd harmonic series in the magnetometer signal of Figure 1 appears more strongly in the magnetometer signal when the magnetometer is near to flashing LEDs (link indicators) on the ADNACO-R1BP1B board (photos are also included in Figure 1). The coherence at LED frequencies between the magnetometer and the blank ADC channels reaches 0.1. The blank ADC channels are coherent with each other at the LED frequencies even when there is no magnetometer  connected, so the signal on the blank channels isn’t cross talk, and is probably associated with the periodic load on the power supply.

Dave B. notes that if the system were working as expected, the link LEDs should not be flashing.

In addition to the near-1 Hz comb, there was also a 1.000 Hz comb. Figure 2 shows that a 1.000 Hz peak, appears strongly (1 count) in ADC channel 31 (the duotone channel), and less strongly in other ADC channels (coherence reaching 0.01).  The LED flash peak is also apparent at 0.94 Hz in Figure 2, though all ADC channels are blank. Both peaks have an associated comb, odd harmonics for the LED peak and all harmonics for the 1 Hz peak.

The second page in Figure 2 shows that the duotone signals are at about 10^4 times the size of the 1 count peak at 1 Hz. The direct cross talk of the 960 and 961 Hz lines in, say, channel 15, visible in the power spectrum plot of the second page of Figure 2 at about 4e-2 counts, does not seem large enough to produce the 1 Hz comb in channel 15 through the same 1e-4-scale non-linear mechanism.  It may be that the 1 Hz comb on other channels has a different source or mechanism. We might be able to modify the duotone, such as by avoiding the zero cross region, to further study this. Since search groups had problems  with1.000 Hz and near-1.000 Hz combs in DARM during O2, I think it is important to understand/eliminate these peaks.

A final issue was that, although drifting peaks were reduced when the I/O and the AA chassis were placed on linear supplies, I found drifting peaks (Figure 3) in a couple of many spectra. I suppose that this peak could be associated with some rouge oscillator in the chassis.

Dave Barker, Sumeet Kulkarni, Philippe Nguyen, Robert Schofield

J. Kissel

Using the lock stretch that Sheila called out in LHO aLOG 43263, I gathered data that shows the new violin mode forest after we've replaced ETMX, ETMY, and ITMX (with ITMY been exposed to air for ~9 months, which undoubtedly also changes the violin mode frequencies). Attached are comparisons of the Fundamental (~500 Hz), 1st Harmonic (~1000 Hz), and 2nd Harmonic (~1500 Hz) DARM ASDs from O2 (after the July 2017 EQ) and this most recent lock stretch.

I've begun to update the LHO violin mode table (Violin_Mode_Table_v2) in prep for identification of this new forest. I've used the in-air data from LHO aLOGs 40525, 42180, 38857.

So far, I can identify 29 of the fundamental 32 modes, with a 2 mHz resolution. They're tabulated below (and not yet in the table), since I've not yet associated them with a test mass (though some appear to be "obvious" given the large separation).

In hopes to identify the mode Sheila calls out as the worst, I've pushed a 503.085 Hz filter to all new test masses, on MODE 1. This way when we do get a decent lock stretch, we can identify the mass "passively" by turning on the filter with some small gain, to see on which test mass we get action. As before, we'll started by assuming the mode is controllable by driving in Pitch.

In order to gather this data, I just used the standard violin mode templates from O2 (see LHO aLOG 37921), which are linked off of the VIOLIN MODE monitor MEDM screen.