Displaying reports 48261-48280 of 85578.Go to page Start 2410 2411 2412 2413 2414 2415 2416 2417 2418 End
Reports until 10:02, Monday 28 August 2017
H1 AOS
paul.marsh@LIGO.ORG - posted 10:02, Monday 28 August 2017 (38395)
PCalY Rx Signal Stability

Based on some concern about various clipping possibilities in EndY, Travis S. removed irises in the EY Rx side on Aug 15 (see WP 7111; this says EX but was fixed to say EY in paper book). When Sudarshan evaluated calibration data after this (alog 38235), he found that Rx calibration values had returned to "non-clipping" values from prior to end of May.

I wanted to confirm that this was true over time, not just on the day of calibration, so I pulled up the last 6 months on Dataviewer; see results in the attached photo. It seems the Rx PD does flatten out over the 2 weeks since iris removal.

Rick, Travis, and I are currently under the assumption that this indicates clipping at the iris due to small apertures being aligned at high incidence angles. However, this is far from conclusive and will need to be monitored for several more weeks or months. This also does not provide any clues as to the cause of the monotonic drop in output voltage since June.

Images attached to this report
H1 AOS (TCS)
thomas.vo@LIGO.ORG - posted 22:51, Sunday 27 August 2017 (38392)
Both ETM HWS Measurements Done

First I got the IFO to DC Readout so that IR is resonant in both arms, then opened the ALS shutters and misaligned PZT2 on each arm according to  ALOG 35979.

The reference images were taken at 04:13:00 UTC (21:13 PST) on 2017-08-28.  Then power up occurred at 04:21:50 UTC and reached nominal power at 04:24:30 UTC. 

I've shuttered the ALS at  05:42:00 UTC and reset the PZT loops to their nominal bias values.

H1 SUS
sheila.dwyer@LIGO.ORG - posted 19:42, Sunday 27 August 2017 - last comment - 09:51, Wednesday 20 September 2017(38387)
in lock charge measurements

On friday Thomas and I ran excitations on all 4 ESDs in order to measure the 4 coefficients in this equation for the force applied by the ESDs (G1600699) Equation 2:

F = α (V_b-V_s)2 +β (V_b+V_s)+ β _2(V_b-V_s)+γ (V_b+V_s)2

The first 2 excitations for each suspension were on the bias path with no signal voltage so that the linear response is:

F = [β+β_2+2(α+γ)V_b] δV_b

The bias path was excited twice, first with the normal bias of 380 V on and second with no bias. Then the script excited the signal path which gives a linear response of:

F = [β-β_2+2(α+γ)V_b+2(α-γ)V_s] δV_s

This path is excited 3 times, once with no DC offset on any electrodes, once with an offset of 7.6Volts on the signal electrodes, and once with the bias at its normal value of 380V.

The first 4 of these measurements allow us to make a complete measurement of all four coefficents, α, β β_2, and γ The fifth measurement is redundant and could be skipped, I used it as a sanity check.  I am still worried that I have some signs wrong which are making these results confusing.  

  ETMX ETMY ITMX ITMY
α (N/V^2) 2.1e-10 2.0e-10 8e-11 5.5e-11
β(N/V) -9.9e-10 2.0e-8 1.0e-8 5.6e-9
β_2 (N/V) 2.8e-9 3.2e-8 -4.2e-9 -8.5e-9
γ 1.5e-10 1.2e-10 -4.0e-11 -1.2e-11
V_eff = (beta-Beta2)/(2*(alpha-gamma)) -31 V -75 V 60 V 105 V

All of the scripts needed for taking the measurement and getting the coefficents are in userppas/sus/common/quad/scripts/InLockChargeMeasurements/

Non-image files attached to this report
Comments related to this report
sheila.dwyer@LIGO.ORG - 20:01, Monday 28 August 2017 (38409)

The table above is wrong because of multiple minus signs (which are different between the ITM and ETM ESD drivers) being wrong.  Here is a corrected table:

  ETMX ETMY ITMX ITMY
α (N/V^2) 9.6e-11 8.7e-11 4.9e-11 5.8e-11
β(N/V) -1e-9 2e-8 -1e-8 -5.6e-9
β_2 (N/V) 2.8e-9 3.2e-8 4.2e-9 8.5e-9
γ 2.6e-10 2.3e-10 -9.2e-12 -1.5e-11
V_eff = (beta-Beta2)/(2*(alpha-gamma)) 12 38 -124 -97

 

sheila.dwyer@LIGO.ORG - 09:51, Wednesday 20 September 2017 (38718)

The values in this table still had some calibration errors.  New log coming soon. 

LHO General
kyle.ryan@LIGO.ORG - posted 19:18, Sunday 27 August 2017 (38390)
Tourists from Czech Republic on site unescorted
1515 -1915 hours local -> Kyle R. on site

At around 1800 hrs. local as I was walking between the VPW and the OSB, I happened upon 15 non-escorted people, all wearing matching T-shirts taking a group photo by the BT section display outside of the exterior OSB Control Room Hallway door.  They said that were with "AldeBaran alph Tau" from the Czech Republic and were touring the Western USA - mostly scientific points of interest. They demonstrated a familiarity with LIGO and had already made it past the "ISIS" gate, so I gave them an impromptu tour.  I escorted them into the Control Room (Sheila D. present) then on to the overpass.  Afterwards, I walked them to their cars.  They hoped to call on Monday and arrange for an "actual" tour.  They also said that LHO was their last stop before flying out of Portland OR. in two days time.  
H1 CDS (DAQ, ISC, SUS)
david.barker@LIGO.ORG - posted 16:45, Sunday 27 August 2017 - last comment - 20:27, Sunday 27 August 2017(38388)
h1lsc, h1omc, h1susitmx and h1susitmy model changes, DAQ restart

WP7120 Sheila and Dave:

The h1lsc model was modified to add two new SHMEM IPC senders. The h1omc model was modified to add two new SHMEM receivers (for the new h1lsc channels) and two new PCIE (Dolphin) sender channels. Each of the SUS ITM models were modified to add one new PCIE receiver channels to receive from h1omc.

The models were compiled and installed, the modifications to H1.ipc is shown below.

The models were restarted in the order: h1lsc, h1omc, h1susitmx, h1susitmy.

Because IPC receivers had been added, their slow channels were added to the DAQ INI file, requiring a DAQ restart.

After the DAQ was restarted, I discovered two things:

1. I forgot to check the write status of h1tw1 before restarting. I have checked that h1tw1 was writing raw minute trends every 5 minutes.

2. The EDCU did not come back to a GREEN status. The reason is that a new Guardian node ALS_DIFF_ETMY_ESD had been created (and added to the Guardian DAQ INI file) but is not being ran. We'll fix this tomorrow, for now the EDCU is RED, and it is missing these 19 guardian channels. The disconnected channel list is shown below.

ALS_DIFF_ETMY_ESD Guardian DAQ channels (disconnected):

H1:GRD-ALS_DIFF_ETMY_ESD_VERSION

H1:GRD-ALS_DIFF_ETMY_ESD_EZCA

H1:GRD-ALS_DIFF_ETMY_ESD_OP

H1:GRD-ALS_DIFF_ETMY_ESD_MODE

H1:GRD-ALS_DIFF_ETMY_ESD_STATUS

H1:GRD-ALS_DIFF_ETMY_ESD_WORKER

H1:GRD-ALS_DIFF_ETMY_ESD_LOAD_STATUS

H1:GRD-ALS_DIFF_ETMY_ESD_ERROR

H1:GRD-ALS_DIFF_ETMY_ESD_CONNECT

H1:GRD-ALS_DIFF_ETMY_ESD_EXECTIME

H1:GRD-ALS_DIFF_ETMY_ESD_STALLED

H1:GRD-ALS_DIFF_ETMY_ESD_NOTIFICATION

H1:GRD-ALS_DIFF_ETMY_ESD_NOMINAL_N

H1:GRD-ALS_DIFF_ETMY_ESD_REQUEST_N

H1:GRD-ALS_DIFF_ETMY_ESD_STATE_N

H1:GRD-ALS_DIFF_ETMY_ESD_TARGET_N

H1:GRD-ALS_DIFF_ETMY_ESD_OK

H1:GRD-ALS_DIFF_ETMY_ESD_ARCHIVE_ID

H1:GRD-ALS_DIFF_ETMY_ESD_TIME_UP

H1.ipc additional channels:

[H1:LSC-OMC_ITMX]

ipcType=SHMEM

ipcRate=16384

ipcHost=h1lsc0

ipcModel=h1lsc

ipcNum=59

desc=Automatically generated by IPCx.pm on 2017_Aug_27_13:36:33

 

[H1:LSC-OMC_ITMY]

ipcType=SHMEM

ipcRate=16384

ipcHost=h1lsc0

ipcModel=h1lsc

ipcNum=60

desc=Automatically generated by IPCx.pm on 2017_Aug_27_13:36:33

 

[H1:OMC-ITMX_LOCK_L]

ipcType=PCIE

ipcRate=16384

ipcHost=h1lsc0

ipcModel=h1omc

ipcNum=385

desc=Automatically generated by IPCx.pm on 2017_Aug_27_16:09:43

 

[H1:OMC-ITMY_LOCK_L]

ipcType=PCIE

ipcRate=16384

ipcHost=h1lsc0

ipcModel=h1omc

ipcNum=386

desc=Automatically generated by IPCx.pm on 2017_Aug_27_16:09:43

 

Comments related to this report
david.barker@LIGO.ORG - 16:47, Sunday 27 August 2017 (38389)

Here is the start log for this afternoon's changes:

2017_08_27 16:16 h1lsc

2017_08_27 16:18 h1omc

2017_08_27 16:18 h1susitmx

2017_08_27 16:20 h1susitmy

2017_08_27 16:23 h1broadcast0

2017_08_27 16:23 h1dc0

2017_08_27 16:23 h1fw0

2017_08_27 16:23 h1fw1

2017_08_27 16:23 h1fw2

2017_08_27 16:23 h1nds0

2017_08_27 16:23 h1nds1

2017_08_27 16:23 h1tw1

 

sheila.dwyer@LIGO.ORG - 20:27, Sunday 27 August 2017 (38391)

These model restarts were intended to allow us to send the DARM signal to the ITMs.  Previously, the LSC model had PCIE IPCs to the ITMs, while for the ETMs the LSC had shared  memory IPCs to send the signals to the OMC model, where they are summed with the DARM signals and send to the end stations using RFM IPC.  

Today Dave and I modified the models so that the ITM signals would be routed in a way more similar to the ETMs, so that the LSC has PCIE SHM IPCs to send the signals to the OMC model, then PCI IPCs to send the signals to the ITMs.  

We were able to relock fine after this, but the LSC feedforward which is routed through the new IPCs is not well tuned.  For MICH,  we used to operate with a filter gain of -15.9, today I got some decent MICH subtraction (not well tuned) with a gain of +600.  For SRCL we started to get a small amount of subtraction with a gain of around 22, while our nominal gain was -1.  

I don't understand why this is happening, but will leave the IFO to Thomas Vo for some Hartman tests.  Hopefully we look at what happened early in the morning. 

H1 SEI (SEI)
sheila.dwyer@LIGO.ORG - posted 14:48, Saturday 26 August 2017 - last comment - 13:49, Monday 28 August 2017(38382)
BS ST1 CPS trips

I came in to lock the IFO for Adam's injections which are scheduled for 2 hours from now, (38380), but have had about 4 BS ISI ST1 CPS trips in the last hour. 

Two of these might have happened while the BS was isolating stage 2 (I have not double checked) but at least one happened while we were just sitting in CHECK_IR (no feedback to the BS sus, ISI state should not have been changing).  The screenshot attached is for that most recent trip in CHECK_IR

Edit:  Made it to a fully locked interferometer and was engagning ASC when it happened again, again it was a glitch in the ST1 H3 CPS.  Second screenshot 

Edit again: This seems very similar to the situation described in 37499, 37522 the third screenshot shows the glitches getting worse over the last 1:40 minutes.  Jim describes power cycling the satlite racks which seemed to make the problem go away last time. 

Another update: I power cycled the 3 top chassis in the CER rack SEI C5, these are labeled BSC ISI interface chassis and have cables going to BSC2 CPSs, GS13s and L4C's.  The ISI has not tripped in about 20 minutes, I am relocking but paused to damp violin modes.

Images attached to this report
Comments related to this report
hugh.radkins@LIGO.ORG - 13:49, Monday 28 August 2017 (38403)

No glitches since ~2230utc 26 Aug.  Made note in FRS 8517.

H1 CDS (DAQ)
david.barker@LIGO.ORG - posted 09:45, Saturday 26 August 2017 (38381)
CDS O2 restart report: Thursday 24th - Friday 25th August 2017

Last O2 report:

model restarts logged for Fri 25/Aug/2017
2017_08_25 17:06 h1sysecatc1plc1sdf
2017_08_25 17:06 h1sysecatc1plc2sdf
2017_08_25 17:06 h1sysecatc1plc3sdf
2017_08_25 17:06 h1sysecatx1plc1sdf
2017_08_25 17:06 h1sysecatx1plc2sdf
2017_08_25 17:06 h1sysecatx1plc3sdf
2017_08_25 17:07 h1sysecaty1plc1sdf
2017_08_25 17:07 h1sysecaty1plc2sdf
2017_08_25 17:07 h1sysecaty1plc3sdf
2017_08_25 17:09 h1pslopcsdf
2017_08_25 17:13 h1hpipumpctrlsdf

50 minutes after the end of O2, h1build froze up and required a reboot. The Beckhoff SDF models were then restarted.

model restarts logged for Thu 24/Aug/2017 No restarts reported

 

H1 INJ (DetChar, INJ)
adam.mullavey@LIGO.ORG - posted 07:18, Saturday 26 August 2017 - last comment - 08:16, Thursday 07 September 2017(38380)
Another attempt at Detchar Safety Injections

Sheila plans to come in and lock the IFO this afternoon, so that I can try to finish these detchar safety injections. I've schedule 7 injections, the first one will begin at 16:06:22 PDT, and the last at 16:51:22 PDT. Here is the update to the schedule:

1187824000 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt
1187824450 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt
1187824900 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt
1187825350 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt
1187825800 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt
1187826250 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt
1187826700 H1 INJECT_DETCHAR_ACTIVE 0 1.0 detchar/detchar_27July2017_PCAL_{ifo}.txt

The IFO should be left out of observation mode. Also, I'm not sure if the PCALX 1500Hz line gets turned back on, but this also needs to be turned off. Simply typing the following on the command line will do the trick:

caput H1:CAL-PCALX_PCALOSC1_OSC_SINGAIN 0
caput H1:CAL-PCALX_PCALOSC1_OSC_COSGAIN 0

Comments related to this report
sheila.dwyer@LIGO.ORG - 15:56, Saturday 26 August 2017 (38383)

The interferometer is locked in Nominal low noise and the PCAL X 1500 kHz line is off as of 22:55 UTC.  I hope that the BS ISI will not trip during the injections.  (alog 38382)

sheila.dwyer@LIGO.ORG - 16:42, Saturday 26 August 2017 (38384)

The interferometer unlocked just before 1187825964, so I think that 4 or 5 of these injections would have completed before it unlocked.  I don't know why it unlocked.

adam.mullavey@LIGO.ORG - 20:39, Saturday 26 August 2017 (38385)

According to the guardian log (see attached), the first 5 of these injections made it in. The fifth one ended at 1187825913 (about 50secs before the lockloss). This should be enough injections for now. Thank you Sheila for coming in on a Saturday afternoon and locking the IFO for us!

joshua.smith@LIGO.ORG - 04:43, Monday 28 August 2017 (38393)DetChar

Short version: I made omega scans for the 5 sets of injections that were done above andyou can find them here: https://ldas-jobs.ligo-wa.caltech.edu/~jrsmith/omegaScans/O2_detchar_injections/ (note that after the first set the rest of sub-directories of the start time for each set). 

Long version: The Injection files are here: https://daqsvn.ligo-la.caltech.edu/svn/injection/hwinj/Details/detchar/. These are timeseries sampled at 16384 Hz and they start at the injection times listed in the original entry above. Times of the injections start 0.5s after times given in alog, and are separated by 3s each. Some simple Matlab to plot (attached) the injection file and print a list of times is: 

% Plot hardware injections
fnm = 'detchar_27July2017_PCAL_H1.txt';
data = load(fnm);
t = 0:1/16384:(length(data)-1)*1/16384;

figure;
plot(t,data)
xlabel('time [s]')
ylabel('amplitude [h]')
title(strrep(fnm,'_','\_'))
orient landscape
saveas(gcf,'injections.pdf')

% Print times of injections
t_start = 1187824000+0.5;
times = t_start:3.0:t_start+106;
fprintf('%.2f
',times)

To submit the omega scans I used wdq-batch like so: (gwpysoft-2.7) [jrsmith@ldas-pcdev1 O2_detchar_injections]$ wdq-batch -i H1 times-1.txt, then submitted the resulting dag to Condor. 

OmegaScan results are here: https://ldas-jobs.ligo-wa.caltech.edu/~jrsmith/omegaScans/O2_detchar_injections/

These will take some hours to run and we will then look at the results to see if there are any obvious unsafe channels. In addition we'll look statistically using hveto. 

Images attached to this comment
thomas.abbott@LIGO.ORG - 14:10, Wednesday 30 August 2017 (38458)

This is the equivalent comment to the comment for L1's detchar injections hveto safety analysis on page 35675

I ran hveto_safety on the injections mentioned above, looking for coincidences within 0.1sec time window. 

The results of the analysis using >6 SNR omicron triggers can be found here: https://ldas-jobs.ligo-wa.caltech.edu/~tabbott/HvetoSafety/H1/O2/safetyinjections/D20170826/results/H1-HVETO_omicron_omicron-1187823990-125/safety_6.html

The configuration for the analysis can be found here: https://ldas-jobs.ligo-wa.caltech.edu/~tabbott/HvetoSafety/H1/O2/safetyinjections/D20170826/results/H1-HVETO_omicron_omicron-1187823990-125/H1-HVETO_CONF-1187823990-125.txt

 

 

thomas.abbott@LIGO.ORG - 08:16, Thursday 07 September 2017 (38548)

I missed that there we 4 extra sets of injections, so I've redone the hveto safety analysis on the complete set of 180 injections.

Results: https://ldas-jobs.ligo-wa.caltech.edu/~tabbott/HvetoSafety/H1/O2/safetyinjections/D20170826/results/H1-HVETO_omicron_omicron-1187823990-1925/safety_6.html

H1 ISC (TCS)
sheila.dwyer@LIGO.ORG - posted 22:31, Friday 25 August 2017 (38379)
first sets of measurements post O2

Thomas Vo, Sheila Dwyer

We started out pre vent/discharging measurements in tonight.  

Non-image files attached to this report
H1 CDS
jonathan.hanks@LIGO.ORG - posted 17:18, Friday 25 August 2017 (38378)
Restart h1build due to a kernel panic

The CA sdf systems stopped.  After a quick investigation it was found that the server running the SDF systems had locked up.  H1build had suffered a kernel panic and needed to be restarted.

I manually started the following SDF models:

h1sysecatc1plc1sdf 
h1sysecatc1plc2sdf 
h1sysecatc1plc3sdf 
h1sysecatx1plc1sdf 
h1sysecatx1plc2sdf 
h1sysecatx1plc3sdf 
h1sysecaty1plc1sdf 
h1sysecaty1plc2sdf 
h1sysecaty1plc3sdf
h1pslopcsdf 
h1hpipumpctrlsdf 

LHO General
corey.gray@LIGO.ORG - posted 16:48, Friday 25 August 2017 (38377)
And At The Strike Of 3pm PDT, H1 (& L1 & V1) Were Done With O1!!!!

Attached are photos for our End Of O2 Toast at LHO!  :)

Images attached to this report
LHO General
patrick.thomas@LIGO.ORG - posted 16:38, Friday 25 August 2017 - last comment - 09:23, Monday 28 August 2017(38376)
Ops Day Shift Summary
TITLE: 08/25 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY: Last shift of O2! No issues until Beckhoff SDF died during Adam's detchar safety injections. Jonathan has restarted h1build and it is currently running a file system check. Intention bit set to commissioning. Observatory mode set to commissioning. IFO at NLN.
LOG:

16:02 UTC Powercycled video2. MEDM screen updates were intermittent.
16:07 UTC Restarted the range integrand DMT that is displayed on video0. It had been running locally on video0 instead of through ssh on nuc6.
17:23 UTC Gave Adam M. remote access to cdsssh and h1hwinj1.
18:50 UTC GRB verbal alarm. Confirmed with LLO.
15:00 UTC End of O2! Set observatory mode to calibration. Changed INJ_TRANS guardian node to INJECT_SUCCESS.
22:43 UTC Adam M. starting detchar safety injections. Set intent bit to commissioning. HFD to mid X to check on RFAIR box.
~23:09 UTC Beckhoff SDF died. IFO_LOCK guardian node went into error (lost connection to SDF channels). Adam's injections interrupted. Jonathan investigating.
23:23 UTC Jonathan restarted h1build and it is running a file system check. Adam canceling remainder of injections. Transitioned observatory mode to commissioning.
Comments related to this report
patrick.thomas@LIGO.ORG - 09:23, Monday 28 August 2017 (38394)
15:00 UTC should be 22:00 UTC.
LHO VE
kyle.ryan@LIGO.ORG - posted 19:22, Tuesday 22 August 2017 - last comment - 10:09, Sunday 27 August 2017(38315)
TMDS training session at X-end
Rai W., Mike Z., Daniel S., Jeff K., Chandra R., Kyle R. 

Today the TMDS Gas Delivery Table was transported to the X-end VEA and set it up for operation.  The actual Surface Discharge Ionizer was mounted on a stand for today's demonstration purposes.  Nominally, it would be mounted to the dedicated TMDS port of BSC9's East Door.  The Vent/Purge air supply was ran and dry air supplied to the TMDS setup.  Prior to exposing the Ionizer to the conditioned air supply, the plumbing connection at the Ionizer was decoupled and connected to a test setup that facilitated the measurement of > 0.3 micron and > 0.5 micron particulate in the conditioned air. The air line was then re-coupled to the Ionizer.  An approximate 50/50 mix of Ethylene Glycol to Alcohol along with "chunks" of dry ice was used as a cold trap to the path.  

Rai W. gave an overview of the theory and a detailed tutorial as to the operation of the setup.  Daniel S. and Jeff K. noted details related to the ion production while Kyle R. and Chandra R. noted detail related to the vacuum related issues.  

The Ionizer setup performed satisfactorily (with caveats) at making comparable amounts of positive and negative ions.  

The plan now is to connect the Ionizer to BSC9 and perform an actual discharge of the ETMx during next Tuesday's maintenance day.  

My notes from today; 

1. Oscillations were noted and attributed to electronics design -> Daniel S. will address.  
2. Rai W. requested that we provide a means of support to take the weight of the Ionizer when mounted to the 1 1/2" valve on the BSC -> Kyle R. will address.  
3. Confirmation of the preferred means to pump to rough vacuum the X-end VE between cycles of discharge gas admission -> Chandra R. will address.  

Non-image files attached to this report
Comments related to this report
chandra.romel@LIGO.ORG - 09:53, Wednesday 23 August 2017 (38327)

We will use the QDP80 to pump down the chamber between discharge cycles, with the turbo spun down and, as needed, use purge air to regulate the pump-side pressure to match the chamber pressure as to not break the 10" gate valve rated for 10 Torr differential pressure. Attached is a plot from LLO discharge. They spun up and down the turbo between cycles, but decided later it was not worth the trouble.

Images attached to this comment
jeffrey.kissel@LIGO.ORG - 20:30, Thursday 24 August 2017 (38358)CDS, DetChar, ISC, SUS, SYS, VE
Refer to Figure 1 of T1400713, TMDS design document for elements of setup.

A couple of useful videos of the oscilloscope readouts during the experiment:

Lesson 1: Control and readback of the electrometer from the TMDS inferface chassis, D1500152.
    Rai has set up the readback of the electrometer with the square-wave input shown on the blue trace, and the electrometer readback in yellow. One is looking for an even balance in voltage from the positive and negative ions. The electrometer has a negative voltage bias at the time of recording, so it appears as though we're getting more positive than negative ions, but, rest assured, we're good. 

Lesson 2: Demonstration of ionic discharge against TMDS chamber walls, if HV supply to ion generator is too high.
    The readback of the HV current is shown on the yellow trace. The video starts out with the ion generator discharging, as is evident by the rattiness of the waveform. At the last few seconds of the video, he reduces the VARIAC HV transformer gain, bringing the ion generator back to the desired level.

Lesson 3: Demonstration of electrometer readback once HV voltage is reduced
    Once the HV is tuned with the VARIAC, with the initial max amplitude of the square wave generator, then the square wave amplitude may be reduced to ~ 3 V pkpk (assuming a flow rate of about 30-50 [mL/s ?? not sure about those units]). Once we did this, we saw evidence for a ~3 MHz oscillation on the electrometer readback. Investigating the circuit drawing for the electrometer board (D1500061), Daniel and Mike agreed to replace the readback's output resistors R9 & R10 with ~100 [ohm] resistors. 
This has been done already, and the electrometer has been reinstalled

Lesson 4: Final setup of readback / monitor system, in the "ready to discharge into chamber" configuration.
    Once again, Rai demonstrates the control of the HV VARIAC and the desire to keep the ion generator current readback from any rattiness in its waveform, which is indicative of ionic breakdown discharge against the TMDS chamber walls.

I attach a ton more pictures of the setup as well. Hopefully the filenames are a good enough caption.
Images attached to this comment
kyle.ryan@LIGO.ORG - 10:09, Sunday 27 August 2017 (38386)
Desired gas flow rate 30 - 50 Liters per Minute (LPM)
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