Something is wrong with ITMX HWS. I need help from experts.

As I wrote yesterday (26185), because the HWS codes were not running, I had restarted both ITMX and ITMY HWS codes. Today I checked the output, in particular the spherical power, and noticed that the noise level was way too high (+/- 200 uD !). I restarted the code with a new reference image to see if it helps, but it actually made the noise level worse. Now it fluctuates as big as 0.03 uD. Looking at the camera image itself, I saw a beam on the center and assumed that it was the right one. Also I steered the ITMX compesantion plate (which is now intentionally steered by approximately 500 urad due to the green view port issue, 26164) back to the zero-offset angle, but this did not help at all. The laser power has dropped to 1.1 mW which used to 1.4 mW on March 1st (25806), but I believe that this should not increase the noise level such drastically.

One suspicious thing I found is the number of centroids which now reads only 65. In the past it was 400. In summary, I have no idea what has gone wrong.

[Stefan, Sheila, Jenne, Kiwamu, Hang]

Tonight ended up being a night of retuning the PRC2 loops, to make them sensible.  Now they have UGFs around 2 Hz, rather than ~20mHz. 

The thought was that perhaps this 0.4Hz oscillation that we regularly see is a result of not holding the PRC2 loops tight enough. If the PRC isn't following the motion of the SOFT loops (which move when we power up due to radiation pressure), then we're getting a modulation in the amount of power coupled in to the arms from the PRC.  This power modulation makes the SOFT oscillation even worse.  If we force the PRC to follow the arm pointing, then we won't have this power modulation, so we will hopefully only have to deal with "regular" angular instabilities.

In the end, we tuned the shape of the PRC2 pitch and yaw loops while sitting at ASC_PART3 by compensating the PR3 suspension resonances.  This made the loops beautifully stable, so we cranked up the gain.  For the PRC2_Pit loop, we use the new shape (although low gain) for DRMI_ASC.  For the PRC2_Yaw loop, we use the old loop shape and gain during DRMI_ASC, and then use the new loop shape for the main ENGAGE_ASC steps.  Recall that all DRMI ASC loops except for MICH are turned off after offloading the alignments, and are left off for the carm offset reduction sequence.  Also, during DRMI_ASC, the PRC2 loops actuate on PR2, while they actuate on PR3 in the final state, so it's not quite as weird as it sounds to be using different shapes at different states.

See the attached PRC2 open loop measurements for the OLG after our retuning and gain increases.  All of these sequences have been added to the guardian. 

Now however, when we try to go from 12W to 15W, we see an oscillation in PRC1 Yaw.  We should probably retune the PRC1 loops, including actuating on the lower mass in addition to the top mass of the PRM (right now we only push on the top mass).  We leave this for another day. 

ASC plan for tomorrow:  Run Hang's A2L script, and find SOFT offsets that put us at our actuation nodes.  Hopefully this will reduce the angular effects of increasing the power, and help us get back to 20W.

* Alog title courtesy Stefan

I added H1:VAC-LX_X2_PT170_PRESS_TORR and H1:VAC-LY_Y2_PT180_PRESS_TORR to the exclude channel list and rescanned. 528 channels were added and 2 were removed (see attached). H1:PEM-CS_DUST_LAB1_ENABLE and H1:PEM-CS_DUST_LAB2_ENABLE are still unmonitored.

Corey, Daniel, Stefan

We moved one of the two AS56/45 WFS from the AS port in-air table (ISCT6) to the REFL port in-air table (ISCT1). (Serial number S1300512)

The WFS was connected to the RF cables for the REFLAIR B WFS, and powered by the third slot on the WFS interface chassis.

One thing to note (again) is that those 5-channel RF connetors are impossible to plug in - in fact the only way to guarantee that all connecions are good is to remove both the connector backshell and the WFS box cover, and idividually checking that every channel pin and shield makes a good contact. Corey has some pictures of this.

Also, we quickly wanted to check the RF transfer functions from test in to each channel, but they looked broken. The chain definitely needs to be checked out again.

End Station PI models WP5785

Terra, Betsy, Jim, Dave:

The end station PI models (h1susetmxpi and h1susetmypi) models were changed this morning to permit them to drive the PI inputs to the ESD drives. Prior to this change these channels were being driven by the main quad models. The process was:

remove the drive of the last two channels of the last DAC from ETM[X,Y]

restart the ETM[X,Y] model (to free up the DAC channels)

add the last two DAC channels to the ETM[X,Y]PI model

restart the ETM[X,Y]PI models

Now that the PI models are driving the ESD low voltage inputs, it was important that they stop driving if the main Quad model has stopped driving its DAC channels through either a MASTERSWITCH switch to OFF, or a WATCHDOG trip. This requires two shared memory IPC channels to be added to the ETM[X,Y] models. To get the MASTERSWITCH channel out of the QUAD_MASTER.mdl model, this was changed to add an output port. For the end station models this was plugged into the SHMEM IPC senders, for the corner station ITM[X,Y] this was terminated.

Code checked into SVN r12907

First Version of ITM PI model installed at LHO

Dave:

The first version of the corner station SUS PI model was installed on h1susb123 in the remaining core. This is a 'work in progress' as it does not have any input or outputs and at the moment is essentially a place-holder. This completes the increase in H1 models (along with h1ngn) and brings H1 model total to 104

DAQ Restart

Jim, Dave:

The DAQ was restarted at 14:57 PDT to:

• sync up with SUS ETM[X,Y]PI changes
• add new H1SUSITMPI model
• add DAQ and FEC EDCU entries for the new h1susitmpy and h1ngn models

The DAQ restarted cleanly with no problems.

Filiberto, Patrick, Richard

WP 5784

The major issue encountered was that the X4 PT525 and X5 PT526 BPG402 EtherCAT gauges reported 0 torr after being connected to the end X vacuum chassis. I have not yet been able to figure out why. These gauges have been moved back to h1ecatx1 for now. All of the status information that I could find for them seemed to indicate that they were fine, and that the hot cathode ion gauge was in use (active sensor: 2). Richard measured the voltage directly from the pins on one of the gauges and it reported around 1.72 V, which would have been in the right range. I tried a factory reset by writing to CoE index FBF0 0x01, but it is unclear if a reset occurred. If one did, it did not help. I tried changing the units readback to counts and got a large changing number, but strangely the linked variable still read 0. I will connect a spare BPG402 gauge to the end Y chassis in the EE lab and do some more testing.

In regards to the other changes, I trended the pressure and high voltage for IP 12 and it is back to around what it was before the change to Beckhoff. It is hard to tell at this point if the smoothing for the CP8 pump level is noticeable or improving the PID control.

Now that the commissioners start to use CO2Y I want it to be obvious if it trips.

Kiwamu, Nutsinee

In order to understand the characteristic of the COY rotation stage I ran Kiwamu's script with TCS CO2 channels asking the rotation stage to turn to random angles. The result is attached below. The first plot shows that CO2Y rotation stage works 85%-93% of the time (out of 300 samples). Changing the rotational state speed by 50% didn't make much difference (if not worse). The nominal speed is 100%. When the rotation stage didn't go to the requested angle the difference is always roughly 30 degree. In comparison I attached the second plot showing data from CO2X rotation stage that has quite a nice behavior. The requested angles and measured angles agree within half a degree (out of 100 samples). 

John, Chandra

Connected aux pumping carts to the following annuli:

1. HAM 7/8, with secondary turbo
   Pressure:  3.4e-5 Torr
2. HAM 11/12, with secondary turbo
   Pressure:  9.5e-5 Torr
3. HAM 9, no secondary turbo
   Pressure:  7.0e-4 Torr

Still need to connect BSC4 annulus. 

Two annuli systems are leaking, based on the attached plot of diagonal gauge PT-140. Leak rate (O) e-3 Torr-l/s.

The lock out/tag out for the HPO power supplies was removed.

Both the internal and external shutters of the HPO had their flags replaced.  The
position of the flags were also adjusted so that the magnetic position sensor was
triggered when the shutter was opened/closed.  TwinCAT uses the position sensor
for animation on the user screen.

Each of the four laser heads was powered up, one at a time and with 5 amp increments
up to the nominal pump power (50 A).  No problems were observed with the fibre bundles.
The diode currents were set back to zero.

As we were closing up, a small pool of water was observed on the base plate.  Fortunately
none of it was spraying anywhere.  The source was traced to the flow sensor in head 3.
It was removed, its PTFE tape redone and re-installed.  No leak was observed for a period
of time afterwards but this should be monitored and kept in mind if the crystal chiller
keeps complaining about low water level or a flow sensor problem.

If the front end laser trips out and you do not know how to bring it back on line,
PLEASE ASK or get someone who knows how to do it.



Jason, Peter

I reset the 35W FE power watchdog at 20:52 UTC (13:52 PDT).

re aLog 26140

Here are snaps of 0-120hz spectra for HAMs 2 thru 6 with the reference traces from 13 March (before the switch last week,) and the current traces from this morning at 3am.  Not even really suttle differences so I'd say at least no harm done from the switch to the common timing source.