Below are a basic diagram of what the RTD measurement circuit logically looks like and an example schematic of the actual wiring. The schematic wiring will be placed internally into a chassis, connected to the RTDs via DB25 cable.

cleaning cleanroom and particle count

• 3:37 pm: started particle count
  • zone 3:
    • 0.3 u: 1205
    • 0.5 u: 748
    • 1.0 u: 249
• zone 4:
  • 0.3 u: 1496
  • 0.5 u: 748
  • 1.0 u: 290
• 3:57 pm: began surface check and wipedown, including softwalls. NOTE: vacuum chamber insulation crumbling at edges, dropping loose flakes. Scatters residue whenever jostled, so wiping it down just releases more. Not enough flakes are being released for it to be a major issue, but definitely something to keep an eye on.
• 4:18 pm: started vacuuming the floor
• 4:29 pm: finished vacuuming the floor
• 4:30 pm: started mopping the floor
• 4:35 pm: finished mopping the floor
• 4:36 pm: started cleaning the buckets
• 4:41 pm: started mopping with IPA wipes
• 4:52 pm: finished mopping with IPA wipes
• 4:52 pm: changed sticky floor mats
• 4:53 pm: started particle count
  • zone 3:
    • 0.3 u: 3367
    • 0.5 u: 1787
    • 1.0 u: 914
• zone 4:
  • 0.3 u: 1039
  • 0.5 u: 498
  • 1.0 u: 249

As a follow up ELOG 261, I have received advice from one of the vacuum experts at LIGO Hanford on best practices for our RGA:

1. For future RGA degassing, definitely keep the main volume isolated, since it could contaminate the main volume with everything that just got cooked off of the filament. So the procedure should be to (i) close both gate valves, (ii) ensure the angle valve on the bypass line is open, (iii) initiate the degas cycle on the RGA, (iv) pump the RGA volume through the bypass line, until its pressure returns to its pre-degas level.

2. Repeated degassing of the filament will definitely wear it down much faster, so do this operation sparingly.

3. As long as the pressure of the RGA volume is in the UHV range (~1e-9 torr), best practice is to leave the filament on. This keeps it hot which helps prevent particulate from settling on it. However the electron multiplier should stay off when not actively taking scans, as it will wear down if left on all the time.

[Jon, Shane, Luis]

My repair of the internal ribbon connecting the ADC to the adapter board resolved the timing signal problem. After this repair, we were able to start the front-end IOP model and checked out the RTS diagnostic screens (pictured below). All indicator lights were green except for the DK flag (indicating the DAC outputs are not enabled) and the DAQ flag (indicating that the system is recording data to disk). Those were both as expected, because the DAQD data acquisition service was not set up yet and the DAC outputs are not enabled until at least one user model (which outputs signals to the DAC) is started. I created and installed a simple user model (C1MSC) and confirmed that the DK flag clears once this model starts.

I later attempted to set up the DAQD service, which is needed to save data, but am yet to successfully debug it. I have received some guidance from one of LIGO's CDS experts and will try it at my next opportunity for lab work.

After initial analysis from last week on a single RTD, I then extended to looking at all 8 in series with R_ref (set to 1 kOhm). Shown below are the edge cases for the setup:

• RTDs are all at ambient lab temperature. This would correspond to a minimum resistance value.
• RTDs all read out 400 C. This gives the maximum resistance value.

The results show that indeed only a few mA of current is drawn even at room temperature (a little above 5.5 mA), and this will continue to decrease with increasing temperature. The voltage across a single terminal, at a maximum, is only about 5.4 V.

1. Run a second RGA degas cycle, but next time with the main volume valved off with only the RGA volume being pumped (through the bypass line). This will prevent "boiled off" particulate from entering the main chamber and will also increase the pumping rate for the RGA volume, reducing the amount of particulate that resettles on the RGA filament.
   
   
2. I also noticed that the SRS manual states that the filament is designed to be long-lived and it is recommended to leave it on any time the RGA is on. By leaving the filament on all the time (i.e., hot), we could reduce the amount of particulate that is evidently settling on it between scans. I am checking whether LIGO Lab does this in their own chambers.

cleaning cleanroom and particle count

• 12:30 pm: Tyler and Aiden started organizing cables in cleanroom
• 12:35 pm: started particle count in flow bench
• 0.3 u: 11681
• 0.5 u: 3284
• 1.0 u: 1039
• 12:50 pm: started cleanroom particle count
  • zone 3:
    • 0.3 u: 14549
    • 0.5 u: 10351
    • 1.0 u: 6194
• zone 4:
  • 0.3 u: 10808
  • 0.5 u: 4655
  • 1.0 u: 1953
• 1:07 pm: began surface check and wipedown, including softwalls
• 1:19 pm: started vacuuming the floor
• 1:28 pm: finished vacuuming the floor
• 1:29 pm: started mopping the floor
• 1:33 pm: finished mopping the floor
• 1:34 pm: started cleaning the buckets
• 1:37 pm: started mopping with IPA wipes
• 1:39 pm: finished mopping with IPA wipes
• 1:40 pm: changed sticky floor mats
• 1:41 pm: started particle count
  • zone 3:
    • 0.3 u: 8397
    • 0.5 u: 5071
    • 1.0 u: 2618
• zone 4:
  • 0.3 u: 6651
  • 0.5 u: 4323
  • 1.0 u: 2120

[Jon, Tyler, Shane, Peter, Luis]

Today we completed the first phase of lab clean-up. Activities included:

• CF/KF parts stored under the cleanroom table were removed and transferred to Physics 1129
• Cleanroom workbench cleared, with all FROSTI hardware collected into one of the large SS bins
• High surfaces outside the cleanroom (lights, table enclosure frames, rack, cabinets) wiped down with IPA wipes
• Floor HEPA-vacuumed outside the cleanroom
• Sticky mats changed throughout the lab

Tomorrow, we will complete turn-over of the cleanroom (HEPA vacuuming of floors, mopping of floors, IPA wiping of softwalls and work surfaces). Shane will post a forthcoming measurement of the cleanroom particulate levels, post-turnover.

Preliminary RTD calculations are shown below, given an input of 10 V and desiring a few mA of current. It looks like R_ref should be at least 1 kOhm (refer to plots/circuit below), keeping in mind we need to have <10 V input for the ADC.

RP: The Red Pitaya Software was updated to OS 2.00. All examples on the RP website should run without issue.

• Topmost Sorensen: +24V (reserved for FROSTI)
  • Positive terminal:
  • unconnected for now
  • Negative terminal: [negative terminal is grounded]
  • jumper to Sorensen ground screw
• Sorensen 2nd from the top: +18V
  • Positive terminal:
  • white power cable wire for AA chassis
  • white power cable wire for AI chassis
  • white power cable wire for BI chassis
  • white power cable wire for BO chassis
  • Negative terminal: [negative terminal is grounded]
  • jumper to Sorensen ground screw
  • black power cable wire for AA chassis
  • black power cable wire for AI chassis
  • black power cable wire for BI chassis
  • black power cable wire for BO chassis
• Sorensen 3rd from the top: -18V
  • Positive terminal:[positive terminal is grounded]
  • jumper to Sorensen ground screw
  • green power cable wire for BI chassis
  • green power cable wire for BO chassis
  • Negative terminal:
  • green power cable wire for AA chassis
  • green power cable wire for AI chassis
• Bottommost Sorensen: +6V
  • Positive terminal:
  • white power cabe wire for timing chassis
  • Negative terminal: [negative terminal is grounded]
  • jumper to Sorensen ground screw
  • green power cable wire for timing chassis
  • black power cable wire for timing chassis

FLIR: After some adjustments, the plot generated from the FLIR measurements look much more symmetric (see attachment). There are more included grid points, which smooths out the curve as compared to last week.

Red Pitaya: It looks like a new OS update was released for the RP, which includes a new Python API (was previously only available in C). I'm going to try and update the one we have currently running in lab.

By 5:30 pm Friday, the pressure had reached 8.6e-8 torr and was continuing to fall. So it seems we are OK to proceed with permanentizing this configuration (cable routing, heater tape reinstallation).

cleaning cleanroom and particle count

• 3:16 pm: started particle count.

  NOTE: we are not within the ISO class 5 standard for any size ranges in zone 3. ~6000 above limit in 0.3 u, ~2000 above in 0.5, ~200 above in 1.0

  • zone 3:
    • 0.3 u: 16,711
    • 0.5 u: 5612
    • 1.0 u: 1039
• zone 4:
  • 0.3 u: 6817
  • 0.5 u: 2369
  • 1.0 u: 249
• 3:35 pm: began surface check and wipedown, including softwalls
• 3:50 pm: started vacuuming the floor
• 4:00 pm: finished vacuuming the floor
• 4:01 pm: started mopping the floor
• 4:06 pm: finished mopping the floor
• 4:07 pm: started cleaning the buckets
• 4:08 pm: started mopping with IPA wipes
• 4:14 pm: finished mopping with IPA wipes
• 4:15 pm: changed sticky floor mats
• 4:18 pm: started particle count
  • zone 3:
    • 0.3 u: 23,113
    • 0.5 u: 9686
    • 1.0 u: 1371
• zone 4:
  • 0.3 u: 7191
  • 0.5 u: 2951
  • 1.0 u: 290

Took some RGA data when we came into the room. The pressure of the chamber was 8.63e-8 Torr before turning on the RGA filament. We saw the usual spike in pressure when the filament was initially turned on. Took some data and saw that the chamber was definitely dirtier since the vacuum upgrade. See figures below.

Put the heater tape back onto the section that was removed. We may need to rearrange the heater tape again as there was not much heater tape to go around the upgraded section. We also tried to get some of the extra insulation around this section and we able to get some on around the 6-8 inch reducer.

We then took off the electronics for the gauges and the RGA, added the new extension cords to the PID controllers, and then started bake 6 which will go to 120 degC and stay that way until most likely Monday. The pressure before starting the bake was 8.28e-8 Torr.

Continued tightening bolts on the turbo pump and 6"-8" reducer to reduce the leak. The final leak test values for the turbo pump flange was 3.0 e-9 and the other 6"-8" reducer flange was 4.0 e-9.

We will continue to let it pump down as the screws could not be tightened anymore. Looks like new gaskets will be needed to reduce the leaking on these flanges.

[Jon, Tyler, Aiden, Peter]

Upgrade of the UHV system to a larger turbo pump began today. After obtaining a final RGA scan in the old configuration (Aiden to post), we vented all three volumes and proceeded to disassemble the 4.5"-diameter pump line. We completed installation of the new 6"-diameter pump line to the point where the new turbo pump will attach. This includes a 6" manual gate valve, 6"/2.75" reducing cross, and 6"/8" conical reducing nipple, as pictured below. Strain relief was also installed due to the longer length and greater weight of the new fittings.

Tomorrow we will continue with attaching the Varian TV 551 pump and perform a pump-down test. If this pump is confirmed to be operable, then we will relocate the entire system ~18" closer to the middle of the table and permanentize the setup.

Today's CyMAC work:
• Finished assembling external power supply cable for the timing chassis (see attached image)
• Also did some debugging of AA and AI chassis re: power issues. After testing voltages at various test points on the power regulator board (TP1-TP6) in the AA chassis, it seems like it's the source of the problem. Used bench DC power supply to test, running 15V, and the correct voltage is coming in to the board but something significantly smaller is being output. We're also getting unexpected negative signs on voltage at certain test points, with leads in correct positions
• Upon further examination, it looks like the lights on the filter boards are actually turning on (in both the AA and AI chassis), though it's only 2/4 lights on each board and they are very faint
• Corrected DC on/off switch spade lug orientation in AI chassis.
• Tested AI chassis power regulator board to see if the problem was the same, and found again that voltage coming in was correct, and voltage going out was not.
• In case of interest in exact numbers, results were as follows:
  • Voltage difference between TP1(+Vin) and TP6(-Vin) is ~30V
  • Voltage difference between grounded chassis wall and TP1 (+Vin) is ~15V
  • Voltage difference between grounded chassis wall and TP6(-Vin) is ~-15 V
  • voltage difference between TP2(+Vout) and TP5(-Vout) is ~3V
  • Voltage difference between TP3 (gnd) and TP2(+Vout) is -0.065V
  • Voltage difference between TP5(-Vout) and ground is ~3V

cleaning cleanroom and particle count

• 10:06 am: ran zero count test on particle counter
• 10:07 am: started particle count
  • zone 3:
    • 0.3 u: 2203
    • 0.5 u: 831
    • 1.0 u: 540
• zone 4:
  • 0.3 u: 374
  • 0.5 u: 124
  • 1.0 u: 124
• 10:25 am: began surface check and wipedown
• 10:34 am: started vacuuming the floor
• 10:44 am: finished vacuuming the floor
• 10:45 am: started mopping the floor
• 10:49 am: finished mopping the floor
• 10:50 am: started cleaning the buckets
• 10:57 am: started mopping with IPA wipes
• 11:01 am: finished mopping with IPA wipes
• 11:02 am: changed sticky floor mats
• 11:03 am: started particle count
  • zone 3:
    • 0.3 u: 2535
    • 0.5 u: 374
    • 1.0 u: 166
• zone 4:
  • 0.3 u: 581
  • 0.5 u: 41
  • 1.0 u: 0