Borja, Sheila, Gerardo
As per original plan, and after taking another set of charge measurements in X and Y, today at about UTC 2014-08-20 23:00:00 we turned on the green laser light with a measured power of 57.5mW going into the periscope that injects the beam into the ETMX chamber. In parallel Gerardo turned on the turbo pumps in ETMY and closed the gate valve of the ion pump.
model restarts logged for Tue 19/Aug/2014
2014_08_19 08:56 h1isietmx
2014_08_19 12:00 h1susetmy
2014_08_19 12:00 h1sustmsy
2014_08_19 16:33 h1hpibs
2014_08_19 16:33 h1iopseib2
2014_08_19 16:33 h1isibs
2014_08_19 16:35 h1hpiham4
2014_08_19 16:35 h1hpiham5
2014_08_19 16:35 h1iopseih45
2014_08_19 16:35 h1isiham4
2014_08_19 16:35 h1isiham5
2014_08_19 21:37 h1dc0
2014_08_19 21:38 h1dc0
2014_08_19 21:42 h1dc0
2014_08_19 21:43 h1broadcast0
2014_08_19 21:43 h1fw0
2014_08_19 21:43 h1fw1
2014_08_19 21:43 h1nds0
2014_08_19 21:43 h1nds1
2014_08_19 21:46 h1dc0
2014_08_19 21:47 h1dc0
2014_08_19 21:48 h1broadcast0
2014_08_19 21:48 h1fw0
2014_08_19 21:48 h1fw1
2014_08_19 21:48 h1nds0
2014_08_19 21:48 h1nds1
maintenance work on ISI ETMX and SUS ETMY. Unexpected restarts of SEI B2 and H45. Restart of DAQ following maintenance.
Borja, Sheila
We turned on the laser at end X, so that Borja can do a charging measurement after having green light on for 1 day. To do this Rai would like 50mW of 532nm light on the optic. When we turned on the laser the setttings were 1.843 Amps 31.8 C and for the SHG crystal 33.83 C (set value 33.81C). We measured 54 mW of green out of the laser and 34 mW going into the chamber.
Borja adjusted the doubling crystal temperature to 33.53C actual value (33.51C set value) and the power going into the chamber increased to 38.5mW.
Borja then turned the laser current up to 1.912Amps and the power going into the chamber stabilized at 57.5mW.
We plan to reset the current to the old value after the charging measurement is done, but leave the doubling crystal temperature at this setting.
In order to figure out what is going on with the IMC cavity pole, I made a comparison between a recent and past IMC open-loop transfer functions.
If the cavity pole really dropped to 7.7 kHz from 8.8 kHz, this would cause a measurable change in the open-loop transfer function. According to the comparison, I did not see a large change. This result supports the hypothesis that the IMC cavity pole stayed (almost) the same.
The plot below shows the IMC open-loop transfer functions: one is taken yesterday shown in in blue, and the other was measured on February 7th with the same servo board configuration but with a higher laser power.
As shown in the plot, they look similar to each other except for the gains. The difference in the gains must be due a combination of the different laser power and non-carefully adjusted gain on the IMC servo board. In addition, there is a large discrepancy at high frequencies above 80 kHz, but this is pretty much out of our interested frequency band. So we don't care about it.
* * * *
If the cavity pole really dropped from 8.8 to 7.7 kHz, this would decrease the response above 7.7 kHz by about 12 % in amplitude and also give an extra retardation in the phase by 3-4 degrees at around 8 kHz. In order to check if there is such change between the two transfer functions, I took a ratio of the two TFs -- the plot below shows a transfer function of (recent TF) / (past TF).
Even though the data does not look super smooth, we can already see that there is no 12% drop above 8 kHz in the amplitude or no 3-4 degrees retardation in its phase at around 8 kHz. It rather looks as if the IMC stayed almost the same since February. Also I am attaching a matalb fig file of the same plot in case somebody wants to play with it.
Here are the raw data.
08:33 Tim to EY for B&K cleanup
09:05 Sheila unlocking PMC momentarily
09:45 HAM6 crew to work
09:59 Krishna to EX to check pressure
10:04 Jason to LVEA for SR3 OpLev work
10:19 Gerardo to EX to swap power supply for ion pump
10:50 Andres to LVEA on parts hunt
10:56 Tim to LVEA to check for parts
11:20 Jordan, Paul, and Sudarshan to EX high bay
12:35 Krishna to EX CER
13:51 Jordan, Paul, and Sudarshan to EY high bay
14:30 Jason starting work on HAM3 OpLev
15:05 Dave restarting DAQ
15:06 Borja to EX to turn on green laser
15:57 Jason out of LVEA
I restarted the DAQ to fix a duplicated IOP ini file entry in the master and reinstalled the H1EDCU_GRDLITE.ini file (minus duplicated channels which I accidentally added yesterday). The EDCU is now GREEN, and if it goes PURPLE we should investigate the cause.
Since we have been struggling to understand our measurements of the IMC cavity pole, I had a look at the power in different ports of the IMC.
The IMC visibility is 96%.
MC2 transmitts 1.3mW, where 1.4mW are expected
Paul calibrated the MC2 trans QPD in uW ( alog 9716), there is a 90% splitter between the QPD and MC2, so with the QPD sum at 127.7uW-1.4uW dark offset we have MC2trans=1.26mW. With 1.622Watts input power (measured by PSL periscope PD) we expect 1.622Watts *166( expected IMC build up)*5.1e-6 (MC2 transmission)=1.4mW
The cavity pole measurement (alog 13381 ) would indicate that the IMC build up should be 178, (instead of the expected 168) which would require the transmission of MC2 to have decreased to 4.2ppm.
The IMC throughput is also OK, based on Kiwamu's IM4 trans measurement yesterday (alog 13495 )and assuming the input Faraday has 3% losses, we have an IMC throughput of 90%. If the cavity pole measurement were correct this would require MC3 transmission to have dropped from 0.58% to 0.48%.
The simplest explanation here seems to be that the cavity pole measurement is wrong, and that the IMC hasn't changed.
I centerred the IM4 trans QPD in HAM2 using a picomotor. I moved it from (X,Y) = (0, 0) to (500, 19000). Before I centered it, the beam was not hitting the segment 1 and 2.
Also, I plugged the IO_CAB_243 (see D1200666-v11) to the first input of the picomotor controller box #5. This cable had been disconnected for some reason.
Alexa, Dan, Koji
Using a laser pointer we were able to verify that the four quandrants on each OMC QPD were behaving correctly. We found that the diodes were rotated 90deg from the expected orientation. Koji says this should not be possible given the pinout structure of the diodes, maybe there's something in the cabling between the diode and the ADC.
With confidence in the diodes, we used OM2 and OM3 to walk the beam through the OMC. We observed that the flashes we saw on QPDA yesterday were due to some terrible clipping of the main beam inside the OMC, and using a card and IR viewer we were able to bring the correct beam into the QPD path and center the beam on the OMC QPDs. Success! The sliders on OM2 and OM3 are in the hundreds of counts, which is not terrible but needs to be offloaded eventually.
Right now the beam to the OMC cavity is off in yaw, and the OMC REFL beam is too high in pitch, enough that we can't compensate with the mirrors on the table. We may need to adjust the fixed steering mirror (in a lens holder).
We are close to using the OMC PZT, so we'll need the high voltage to be enabled.
J. Kissel Krishna tried using Brian's /ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/asd2.m function, which requires a prior version of the function, /ligo/svncommon/SeiSVN/seismic/Common/MatlabTools/asd.m however, using the controls account, he ran into problems with a shadowed function in the mDV directory: /ligo/apps/linux-x86_64/mDV/extra/asd.m which is also in the control matlab path (because we need that directory for other useful mDV tools). As such, I've moved the mDV function, /ligo/apps/linux-x86_64/mDV/extra/asd.m to the same location, but with a different name, /ligo/apps/linux-x86_64/mDV/extra/asd_mDV.m It's unclear whether anyone uses this function, but to those people, I'm sorry ahead of time. This directory is not under any sort of repository or version control, so this only changes LHO's local copy of this function. More apologies. This merely reiterates a point recently made that someone needs to maintain and support a library of semi-basic Matlab functions used regularly by commissioners, like asd2, get_data, tfe2, coh2, get_schroeder_tf, autoquack, specexplain, sos2freqresp, readFilterFile, vectfit, etc.
One suggestion had been to import all the 40m stuff under mDV in their CVS. However, this included several MATLAB functions that had identical names to ones in the standard MATLAB libraries. This was why we did not include these at LLO. So we need a repository (likely scrubbed by CDS sys-admins) to hold these (and of course a standard directory for links, as we have for scripts, Perl, etc.)
J. Kissel, K. Venkateswara
The ion pump current this morning was 0.25 mA, which should correspond to a pressure of ~ 5E-7 torr. Looks normal so far and the low pressure should ensure a long lifetime for the pump (~ 5 years).
The data from Tuesday night looks quite good. Unfortunately, we forgot to reset the filters FM1 and FM2 (described in alog 13448 ) for the transfer function correction. This is why the BRS/tiltmeter resonance is visible in Tuesday nights data.
The first plot of the first file shows the ASD of the reference mirror, BRS, STS and the PEM Guralp seismometer. The plot below it shows the coherence between BRS and STS. The wind speeds were about ~ 10 mph.
The second file shows a comparison of the ASD's from Monday and Tuesday nights for the BRS and the STS. There is a clear elevation of the noise floor between few mHz to ~ 0.6 Hz on Tuesday compared to Monday.
All known AA/AI & Whitening chassis that are currently stored in the "H2" building have been opened up and inspected for version6 filter boards. Those with less than version6 that can be updated have been removed and stored in bins in the EE Lab until further action can be taken. A number of filter boards that are marked version5 and then removed to find version6 mods have been done already, have remained removed and a great deal of these boards are being shipped to LLO. Approximately 306 boards have been removed in total for update. It is my understanding that there are some much earlier revisions that may not undergo this modification. There are currently approximately 223 boards in 64 chassis that remain intact for India. All AA/AI & Whitening chassis, regardless of filter board status have received new insulation for the Negative side of the +/- 5V regulator modules.
Attendees: Fred, Keita, Daniel, Robert, Koji, Jodi, Patrick, Ed, Filiberto, Jason, Kiwamu, Krishna, JimW, JeffB, Tim, Gerardo, Terry, Alexa, Aaron, JeffK, Dan
It has been a couple of days without updates on the charge measurements side which does not mean that the activity stopped, actually the total opposite. I will try now to summarize where we are and what is being planned for the very near future.
First of all this entry reports on measurements that follow up the measurements reported here and the previous measurements chronologically compiled here.
Up until now we have only reported on ETMY charge measurements because only this mass has been available. This has recently changed so I will be able to report here the first set of ETMX charge measurement.
But let's continue with ETMY for the moment, although I will once again include a compilation of previous measuremnts, all properly numbered:
1) ETMY was considerably charged before the ionised gas discharge runs were used.
2) Two ionised gas discharge runs were applied to ETMY. The first one had a considerable discharge effect, although not so much the 2nd one which slightly increased the charge. The first discharge run was not ideal with a big ratio between injected positve and negative ions. The second discharge run succesfully increase the total number of ions injected but it failed on its intention to reduce the ration between the negative and positive ions. In order to do this the second discharge run was done with a much reduced aperture of the gate valve at the ETMY chamber. It is now believed that this caused the ionised gas to pass through the labyrinth at the "O" ring and so have a chance for the ions of opposite sign to cancel each other. A third discharge run will be done sometime in September which will correct all this problems.
3) During the ETMY measurements I noticed that I was not able to drive one of the ESD quadrants (labelled LL on the CDS screens). The reason for this is that the LL driving cable was going through the ESD low pass filter box which was actually intended to filter frequencies above 1 Hz of the ESD BIAS. As the driving signal was at 4Hz then it was highly attenuated. This was fixed.
4) The ion pump at ETMY was turned ON. After 4 hours a run a charge measurements and noticed an increase of the ETMY charge to levels observed before any discharge was done. Several issues could be causing it; ion pump, cold cathode on top of the ETMY mass, iluminators pointing to the ETMY and finally a change in the electric field configuration at the ETMY due to the ESD drive cable swap.
5) Keeping the ESD drive cables as in the previous measurement I repeated charge measurement 1 day after (this measurement is identified as "after23", which means measurement 3 after discharge run 2 I will keep this labeling from now on) and the charges increased even further with one quadrant (labeled UR) changing sign in the charge.
6) In order to see the effect of ESD driving cables we swap the LL quadrant driving cable to go again through the ESD LP filter box and then measure charge 1 day after the previous measurement (new measurement is labeled "after24" the related aLOG is here). Between this measurement and previous measurement the charge values did not change for most of the quadrants (which may indicate that swaping the cables has no effect on these measurements) with one exception the quadrant labeled UR (the one which changed charge sign previously has changed sign again to the same sign as the rest of quadrants.
7) On the 14th of August we had the scheduled power cut to LHO, this caused everything to be turned off. However I confirmed that iluminators, cold cathode and ion pump came back shortly after.
8) Each full measurement takes about 1.5 hours. This is mainly due to the high bin resolution used to calculate the spectrum of the pitch and yaw oplev signals. Up until now this resolution is BW = 0.01Hz. To speed up the measurement process I tested that reducing the resolution by half would not have much effect on the standard deviation of consecutive measurements. I drove a single quadrant (UR) at a single VBIAS = +390V and repeated 4 measurements for 3 different BW values (0.01, 0.02 and 0.04). Each measurement is done with Averages = 3, I show next measurement values for pitch and yaw including mean and STD for each BW value. The conclusion of these measurements is that BW values has not a dominant effect on the STD observed so from this point on I will be using BW = 0.02Hz
|
BW |
1 |
2 |
3 |
4 |
Mean |
STD |
||||||
|
Pitch |
Yaw |
Pitch |
Yaw |
Pitch |
Yaw |
Pitch |
Yaw |
Pitch |
Yaw |
Pitch |
Yaw |
|
|
0.01 |
9.3088e-3 |
8.3217e-3 |
9.8845e-3 |
8.756e-3 |
10.777e-3 |
9.0433e-3 |
11.229e-3 |
9.728e-3 |
10.300e-3 |
8.962e-3 |
8.65e-4 |
5.90e-4 |
|
0.02 |
8.2067e-3 |
6.7879e-3 |
8.4317e-3 |
7.0868e-3 |
8.3749e-3 |
7.1369e-3 |
8.3915e-3 |
7.396e-3 |
8.351e-3 |
7.102e-3 |
0.992e-4 |
2.494e-4 |
|
0.04 |
6.0939e-3 |
5.352e-3 |
6.1968e-3 |
5.356e-3 |
6.0822e-3 |
5.4248e-3 |
6.304e-3 |
5.2534e-3 |
6.169e-3 |
5.346e-3 |
1.035e-4 |
0.705e-4 |
9) NOW IS WHERE THE NEW MEASUREMENTS ARE BEING REPORTED: In light of the point above I wanted to confirm that the ESD cabling configuration had definitively no effect on these measurements. So I repeated measurement with the same cable configuration as "after24" (this is provided here attached and labeled "after25") the immediately I changed the cable configuration to the proper version where we can drive the LL quadrant. Unfotunately I was never able to complete that final measurement because the ESD HVA power supply turned off twice during the measurements (the first time I went to turn it on but I decided not to do so the 2nd time just in case something serious was happening). For completeness I attach here the uncomplete measurements which I took ("after26") but the injections were weak most of the time and so I will not include this measurement in the analysis. I compared next the results from this measurement ("after25") with the previous 2 measurements ("after24") and ("after23") and this is what we observe:
Table summary of Veff and slopes for the 3 sets of measurements (notice that the measurement with suffix 23 is in red, the one with suffix 24 is blue and the current one 25 is in green):
|
|
UL - 23 |
UL - 24 |
UL - 25 |
UR -23 |
UR - 24 |
UR - 25 |
LR -23 |
LR - 24 |
LR - 25 |
|
Veff PITCH [V] |
228 |
226 |
220 |
-169 |
-11 |
-184 |
153 |
164 |
169 |
|
PITCH slope [10-7 µrad/V] |
-2.6059 |
-2.6014 |
-1.8133 |
2.3050 |
2.2564 |
1.5825 |
-2.6351 |
-2.6454 |
-1.8588 |
|
Veff YAW [V] |
320 |
305 |
320 |
-11 |
33 |
-71 |
227 |
201 |
242 |
|
YAW slope [10-7 µrad/V] |
-2.2264 |
-2.2153 |
-1.5542 |
2.48879 |
2.4904 |
1.6861 |
2.3077 |
2.3825 |
1.6895 |
The results of these measurements are again interesting. We noticed that the common sign charge quadrants (labeled UL and LR) report a consistent charge in pitch and yaw within a few percent, however the other quadrant (UR) with opposite sign charge it did suffer again a new change in charge sign and an increase respect to previous measurements. I do not fully understand what is causing this charge sign change but the other quadrants at least report a consistent charge saturation. Another important thing to considere is that if you look at the Yaw and Pitch deflection vs VBIAS plots attached which compare the measurements in the table above we notice that "after25" has different slopes per quadrant than for any previous measurement, this was never the case before. This slope is related to the dielectric constant and relative dielectric constant of the test mass, the spacing between test mass and electrodes, and geometry of the electrode pattern, the mass of the test mass and the injection frequency. Certainly none of these parameters should have change with maybe the exception of the spacing between the electrodes and the test mass.
10) The strange results in measurement "after25" happened after the big power cut in the observatory and we know that the ESD HVA was having issues. Yesterday (18th of August) Richard and Filiberto had a look to the ESD HVA power supply and saw no obvious issue. They tested the different ESD HVA outputs and all was fine. However it was suspected that the reason for the powering off of the ESD HVA power supply was that the cold cathode of the pressure system dedicated to the ESD HVA power supply did not turn on since the power cut so this would be enough reason to trigger the power shut of the ESD HVA power supply. Once Richard and Filiberto restarted the cold cathode the ESD was running fine again so I took another measurement of ETMY charge with the proper cable configuration, this is labeled "after27". Again the measurements results are attached to this entry. The results are summary in the next table and compared with the last measurement (after25):
|
|
UL - 25 |
UL - 27 |
UR - 25 |
UR -27 |
LR - 25 |
LR -27 |
|
Veff PITCH [V] |
220 |
172 |
-184 |
66 |
169 |
141 |
|
PITCH slope [10-7 µrad/V] |
-1.8133 |
-1.8914 |
1.5825 |
1.4807 |
-1.8588 |
-1.9162 |
|
Veff YAW [V] |
320 |
244 |
-71 |
59 |
242 |
186 |
|
YAW slope [10-7 µrad/V] |
-1.5542 |
-1.5477 |
1.6861 |
1.6539 |
1.6895 |
1.6863 |
The plots attached here show that the slops are again parallel to previous measurements. So it may be safe to think that something related with the ESD HVA drive affected the measurements labeled "after25". If we ignore those measurements then we observe that the charge of the quadrant that changed sign (UR) as been increasing, while the other quadrants (UL and LR) have decreased charge slightly consistently both in pitch and yaw. However the ion pump is still running and the same is the case of the iluminators and the cold cathode. Why the mass being discharge then? It can still be the effect of the ion pump on the ETMY charge trying to reach an equilibrium.
11) If charge measurements in ETMY was not headache enough, I finally got ETMX available for measurements so I run two measurements 3 days apart. This time no problem was obserbed on the driving of any of its ESD quadrants. And even better; there are no iluminators, the ion pum gate valve was closed since the venting that took place at ETMX between 3 and 4 ago, however the cold cathode is ON. Attached here are the results of the measurements for ETMX, including comparison plots but next I show the summary table:
|
|
UL - 1 |
UL - 2 |
UR – 1 |
UR - 2 |
LR - 1 |
LR - 2 |
LL - 1 |
LL - 2 |
|
Veff PITCH [V] |
27 |
47 |
24 |
27 |
42 |
44 |
42 |
45 |
|
PITCH slope [10-7 µrad/V] |
-1.5217 |
-1.4957 |
-1.4697 |
-1.4823 |
1.1381 |
1.1597 |
1.320 |
1.3208 |
|
Veff YAW [V] |
31 |
50 |
20 |
21 |
43 |
33 |
36 |
40 |
|
YAW slope [10-7 µrad/V] |
-1.7726 |
-1.7629 |
1.5631 |
1.5270 |
1.5498 |
1.6476 |
-1.7523 |
-1.7287 |
All is good news in this comparison table. First, the ETMX charge is very small and second, the charge measurements are repeatable even after three days. Only quadrant UL seems to show an appreciable charge increase equally consistent in both Pitch and Yaw. So this results seems to indicate that the cold cathode does not charge the masses.
After the above results, ETMX has become a very good test bed to confirm ion pump charger hypothesis, but also we will be able to verify if the green light is capable of charging the mass.
12) NEAR FUTURE MEASUREMENT PLAN: As Rai W. pointed out the best shot at getting the most information from EMTX is to do the green light first followed by the ion pump. The green light is a pretty unlikely charger while the ion pump is almost expected to make trouble. That way we most likely get two usefult tests.
So hopefully tomorrow (20th August) I will be turning on green light at ETMX at a power of 50mW (espected resonant power of green light during aLIGO operation). The green light will be running for 1 day and then I will take measurements on the 21st August. At the same time we need to replace the power supply for the ion pump in ETMX which died on the 15th of August after the power cut. Kyle has found a replacement so this will be possible to be done tomorrow. So that on the 21st of August I will be able to turn off the green light and open the gate valve of the ion pump keep it open for 1 day and then meausre charge on the 22nd August.
Also tomorrow we will be turning on the turbo pumps in ETMY and close the gate valve of the ion pump and then monitor the effect that this has on the charge of the ETMY mass.
So hopefully by Saturday the 23rd August I will make a new aLOG entry with the compilation of all these new measurements, and hopefully we will have a more clear picture of what is going on.
Another thing that will give us more light on the various hypotheses about the physics that might be going on at the surface of the test mass, is to find out the sign of the charge on the test mass. This is something I am working on at the moment. Knowing the charge which was partially neutralized by the ioninzed gas injection can give us a clue whether it is electrons from photoeffect or slow disintegration of the injected negative nitrogen ions or positive ions coming from the ion pump.
The DAQ is back up after it was shutdown for a reconfiguration restart at 19:32 PDT. For some reason the monit autostarter failed to restart daqd on h1dc0. This was further compounded by the maintenance changes made this morning which left duplicate slow channels in the configuration. So after a few false restarts I was able to get the system stable.
Here is the data gap on both frame writers.
-rw-r--r-- 1 controls controls 750947268 Aug 19 19:32 H-H1_R-1092537088-64.gwf
-rw-r--r-- 1 controls controls 753765993 Aug 19 21:49 H-H1_R-1092545280-64.gwf
J. Kissel, T. MacDonald We measured a final exploration of ETMY HEPI today to identify the exact mode shape of the 8 [Hz] resonance, given that there were still some ambiguities in yesterdays results. Peppering the piers, boots, housings, crossbeams, and support tubes with hit points, we've nailed it down. The bending point is the crossbeam foot (D020195, see green highlighted part in 2014-08-19_HEPIBoot.pdf attachment) -- the connection point of the suspended stage with the Euler springs. Inward of this foot, everything else is moving in concert -- the crossbeam, the support tubes, and everything else inside the chamber. We took two sets of measurements, one involving tons of points on one pair of piers and crossbeam (that's where we identified the foot as the problem, see HitPattern.pdf), and the other with all four cross beams involved focused more on the crossbeam foot -- as many data points into which we could squeeze the hammer. The "single_side.avi" is the first measurment with only one crossbeam system, and the four "*_both.avi" show the measurement with the whole system. Check out all the visual aides, and be sure to loop your video, since the B&K software doesn't export more than once cycle.
[Alexa Dan Koji]
- We aligned the OM1 transmission path again. The AS_C QPD alignment was reestablished. We can use this QPD as the alignment reference.
- The alignment of the fast shutter was revisited and now we can accommodate the beam without the extra legs. We removed the 20mm leg extentions and the placed the beam dump at the designated place.
- OM2 and OM3 were moved so that we can see the spots on the QPDs.
- We think the beams are on the diodes. In fact the diode SUM outputs are responding to the beam.
However these QPD outputs do not give us linear response to the input alignment.
- We checked the electronics outside of the chamber including the cables from the feedthrough.
They don't show any misbehavior. (Basically we swapped the electronics between OMC QPDs and AS_C.
- We'll investigate the QPD functionality tomorrow.
- We'll want to shake the PZT of the OMC sometime soon.
