[Luke, Luis, Cinthia, Michal, Tyler]

On the 26th Cinthia, Michal, and I took off the insolation on the vacuum chamber and re-routed it to include the new RGA volume. 

The next day Luis and I finished up the last of the flanges to be attached. We attached the Pirani gauge with a conical reducing nipple to the 2.75" port on the vacuum chamber. We then preformed the Helium leak testing, both flanges were quite low the 2.75" flange had a leak of 1.68e-10 torr and the 1.33" flange of 5.5e-12 torr. The leak on the 1.33" flange was so low it was difficult to know how much of it was real and how much was just noise.

[Luke, Tyler, Jon]

On the 3rd we set up the pid controllers for the heater tapes and after putting on the insulation we started heating them up. We first brought it to ~50C and let it stabilize, there was about a 6-7 degree difference between the RGA and the barrel temperature, with the barrel being higher. We then brought it to 60 then 70C it still maintained the slight difference between the RGA and barrel temperatures.

Here is a table of the temperatures of the flanges connected to electronics as I left it.

Notes: I removed the electronics from the pressure gauge (main volume) because while it was below the required threshold it was still quite high compared to the other flanges.

The timing chassis used for the cymac has been shut off due to an unknown issue causing its supplied current to fluctuate. All real-time models will be suspended until a solution is found.

On the 5th I had tried to start baking the vacuum chamber however certain parts of the chamber were getting too hot and causing the controllers to shut off. So I turned them off so that the next day I could rearrange the temperature probes. I then on the 6th set them up so that instead of overshooting the temperature they would be a little low in places.

After being left over night the cooler parts of the vacuum chamber got much closer to the desired temperature of 120C.

Here is a table of the temperatures of the sections of the chamber. Note: After these measurements were taken the PID controllers were set to 125C.

Here is a table of temperature of the flanges that have electronics.

Other temperatures of note:

The optical table was about 38C

The cleanroom was around 33C (~91F)

I measured the temperature of the flanges and reconnected the RGA turning on its filament. I then turned off the PID controllers.

Here is a table that has the temperature of the different parts of the vacuum chamber.

[Luis, Luke}

Three RGA scans were taken. The improvement in the amount of HC in the vacuum is visible across the different measurements. Images are attached.

Below is the dark noise spectrum of the Red Pitaya, which was measured over the course of a weekend. Additionally, I have successfully measured a signal from the photodetectors with the FROSTI as the IR source, so it seems there shouldn't be any worry of these particular detectors not being feasible for the RIN measurement.

Ringheater Update

If the link does not work here is the file.

A quick update on the effective emissivity analysis for the CIT FROSTI testing:

I was able to (roughly) match the OPD data to a referenced COMSOL model, with an applied power of 12.6 W (as seen below). However, when changing the emissivity of the ETM in COMSOL, the dT profiles do not seem to change much. I am not sure as to why this is the case at the moment, and will continue to look further.

Additionally attached are the current RIN measurements of the FROSTI prototype. Shown is the PSDs of both channels, in reference to their individual backgrounds.

The following images compare the RGA scans from 9/23/24, after the first bake with the new vacuum system, with those from 3/14/24, after bake 12 with the old system.

The first image shows a graph of the raw data and includes the calibrated leak for both curves. As we can see, our new system meets LIGO standards of cleanliness.

The second graph contains the plot of the normalized data.

Power point slides

cleaning cleanroom and particle count

• 12:25 pm: started particle count
  • zone 3:
    • 0.3 u: 4614
    • 0.5 u: 872
    • 1.0 u:83
• zone 4:
  • 0.3 u: 2411
  • 0.5 u: 415
  • 1.0 u: 83
• 12:48 pm: began surface check and wipedown, including softwalls
• 1:20 pm: started vacuuming the floor
• 1:30 pm: finished vacuuming the floor
• 1:34 pm: started mopping the floor
• 1:40 pm: finished mopping the floor
• 1:40 pm: started cleaning the buckets
• 1:42 pm: started mopping with IPA wipes
• 1:50 pm: finished mopping with IPA wipes
• 1:51 pm: changed sticky floor mats
• 3:44 pm: started particle count
  • zone 3:
    • 0.3 u: 3207
    • 0.5 u: 624
    • 1.0 u: 83
• zone 4:
  • 0.3 u: 916
  • 0.5 u: 83
  • 1.0 u: 0

I tried adjusting the gain settings on the photodetectors to check if this would help improve the RIN spectra measurements. Overall, it doesn't look like it does, and if anything, looks worse. I assume this is so because as the gain is lowered, the amount of detectable signal from the FROSTI becomes smaller and smaller.

I conducted separate tests on the '5015' and '3010a'. When powered individually, the '5015' outputs a signal at 33.55 MHz with an amplitude of 608 mV. It draws 1 A of current from the power source. The input signal for the '3010a' is 33.54 MHz with an amplitude of 670 mV (peak-to-peak) and a 15 mV DC offset. The output signal from channel 1 is a 65.5 kHz square wave with an amplitude of 3.28 V. The '3010a' draws 0.1 A of current.

Both the '5015' and '3010a' work fine when powered separately. However, when both are powered together, the power source behaves as if there is a short circuit. The current theory is that the switch or breaker is tripping, as it has a 1 A current rating. Since the combined current demand of both devices exceeds 1 A, this may be causing the issue.

Slides for 10/16/2024 Group Meeting

The following figure displays data acquired on 10/09, and it shows that we are no longer below the cleanliness standard. Also, the system's pressure went up to 1.9x10^-8 Torr (approximately 7x10^-9 Torr previously). This might be due to a leak somewhere in the system. More tests will be performed later.

[Ma, Luis, Shane]

Working theory for the timing chassis issues had been that the 1A breaker was tripping and causing the failure of the Valon 5015 and 3010 to output the timing signal correctly. We just tried bypassing the breaker, running 6 V on the benchtop power supply (set the current limit to 1.5A), with the 5010 generating the sine wave to pass to the 3010. All worked correctly, and there were no issues. Square wave outputted by the 3010 was exactly as desired (image attached) at the correct frequency, and this confirms the issue was the breaker, not the valon 5015. Ready to go ahead with ordering a new replacement breaker.

[Luke, Luis, Mary, Ma]

On 10/22/24 Luke, Ma, Mary and myself ran a leak test, the results are displayed below. The overall pressure of the vacuum was 2.0e-8 and the temperature readings were 26C for the RGA and 25C for the main volume.

[Luke, Luis, Mary, Ma]

On 10/22/24 Luke, Ma, Mary and myself ran a RGA scan, the results are displayed below. The overall pressure of the vacuum was 2.0e-8 and the temperature readings were 26C for the RGA and 25C for the main volume.

As we can see, the vacuum is passing cleanliness standards again.

PowerPoint slides new

PowerPoint slides older

We replaced the 1A breaker in the timing chassis today with a 4A one, and tested that all is working well. The chassis successfully outputted the correct signal (image attached). The real time models have also been restarted and the CyMAC diagnostics screen is showing all green flags. Timing chassis has been closed up and reinstalled in the server rack.

The Red Pitaya ecosystem has been upgraded to OS 2.00-35, with a key feature being greater freedom in adjusting the sampling frequency for signal analysis. Before, decimation factors could only be applied if they were a power of 2 (i.e 2,4,8,16,...) up to 65536. Now, the factors can be any power of two up to 16, and any whole number greater than 16 up to 65536. Further information can be found here.

[Luke, Luis]

On Friday, 11/1/24, the MR was unpackaged and cleaned under the flow bench. We noticed an ink stain on one of the corners of the material. After wiping it down with IPA and Vector Alpha wipes, the stain was removed. However, the material showed some wear.

After cleaning, we placed it in the bake station and applied a stainless steel baking protocol. On Tuesday, 11/4/24, the material was removed from the furnace and packaged in a static shielding bag. The MR was wrapped in Vector Alpha wipes.

[Luis, Luke, Ma Michael]

The isolation test was conducted on the vacuum system. Every pump was turned off under vacuum, and pressure measurements were taken every minute for 15 minutes. The results are displayed in the sheet linked at the end of this report. The pressure of the main volume dropped very slowly.

The pressure of the RGA Volume dropped in an exponential manner. The test had to be paused at 11 minutes due to concerns about the pressure exceeding the lowest permitted level for the RGA filament.

After the ISO test was performed, we attempted to tighten the bolts of the small turbo pump on the RGA Volume. However, we noticed that the pressure had increased by nearly an order of magnitude, going from 3.27 × 10^-9 Torr to 1.45 × 10^-8 Torr when both volumes were separated. We conducted a leak test for that particular flange and found a concerning leak of 2.15 × 10^-8 Torr, which had previously been 1.9 × 10^-9 Torr. We believe the copper seal was damaged during the ISO test.

View the results sheet

We've added two low-pass filters in hopes of reducing any potential aliasing that may be introducing additional noise into the power spectra for the RIN measurements. It still looks like the noise levels are too high. Attached below are some recent measurements taken with the FROSTI powered on and off.

slides

Chamber temperature: 23C

Chamber Initial Pressure: ~1.8e-8 main, ~3.5e-8 rga

Did another leak test after monday's work to check how the seal was holding up initial leak was 5.5e-9. I then tried to tighten the bolts a bit more the leak rose to 1.9e-8 about a factor of 4 change.

I checked another flange to confirm that I was preforming the test properly. I measured the elbow to pressure sensor to be 2.2e-11 aproximatly what it was earlier in the month (1.9e-11). 

I ran another isolation test. It is still exponetial. Graph attached.

Thoughts:

I belive at this point that it is a knife edge issue when replacing the gasket I checked both flanges and the new gasket. The tp knife edge seemed perfectly fine, the gasket had very minor scratches, and the reducing cross had very small imperfections on its edge. 

We may want to try and use the liquid sealant or get annealed gaskets for 4.5"

[Luke, Luis]

After the gasket replacement performed on Monday (11/18/24) we let the vacuum pump down to UHV pressure for a couple days. Today (11/20/24) we measured the pressure to be 5.30*e^-9 with a temperature of 22C, and we performed a leak test and RGA Scan.

Here are the results:

We have tested the heater to find emissivity, mounted the heater system to the optical table, and have taken irradiance maps of the heater projected onto the screen.

The heater's emissivity was determined by using a thermocouple in conjunction with the FLIR's temperature calibration. To attach the thermocouple to the heater initially, I used Kapton tape and ran both the wires of the heater and the thermocouple through the heater bridge. This allowed for the heater to rest on an optical post and be observed without anyone directly holding it, but there were some measurement issues. The thermocouple had a very wide range of temperatures it was reading, which may have been due to intermittent contact or a short between the two legs of the thermocouple. To solve this and make the temperature measurements more stable, we pried apart the two ends of the thermocouple (to ensure there was no short) and put tape on either side, leaving the end connection bare. This was then taped to the heater, and the thermocouple was much more stable. We also used a K-type thermocouple that has an adhesive tape on it already, which assisted with the intermittent contact as well. With the thermocouple measuring the temperature of the heater, we could point the FLIR directly at the heater and calibrate the emissivity until the FLIR and the thermocouple agreed. Cassidy's emissivity calculator was also used, as I could input a temperature and observe what the emissivity of an area was based on that temperature. We found the emissivity of the heater to be 0.57.

As a note, when observing the heater with the FLIR, it appeared that there was a hot spot in the center, where the Kapton tape sat. Because the Kapton has a different emissivity than the 304 stainless steel of the heater, the FLIR will read it as having a different temperature than it actually does. When using the FLIR in the future, be sure to ascertain whether there is a temperature difference somewhere or if there may be different emissivities.

Additionally, the first heater that I used was taken to a very high temperature and oxidized. The emissivity of this oxidized heater is not known, but could be good information for knowing how oxidation affects these heaters specifically.

To mount the heater system in front of the screen, I used 1/2'' optical posts and the mount I designed using COMSOL's CAD program. The heater was originally 2.5 inches away from the screen, and has since been moved back by an additional two inches so that we could observe the heater side of the screen with the FLIR. We wanted to see what temperature the heater side of the screen was when irradiated by the heater, and how that compared to the camera side of the screen. When the heater ran at 1.12 W of input power, the heater side of the screen had a max temperature of around 29.7 C, and the camera side of the screen read at about 29.5 C. This means that there is very little thermal loss between the two sides of the screen, and any insulation that the screen's adhesive may have is largely negligible. Additionally, the camera was placed at an angle and undetermined distance for these tests, confirming that the temperature measurements compensate well/don’t depend on changes in angle or distance between the camera and the screen. However, there was spots on the back of the screen that the camera was measuring as hot spots where there shouldn’t have been any. I have included an example below. It would be useful to run a test where the camera is directly on the back of the screen without the heater to characterize the screen and see if the hot spots are physically present on the screen or if this is an artifice of the camera because of something like angle of viewing.

Taking irradiance maps of the screen was straightforward. After checking that the emissivity of the screen is 0.99 by viewing it at room temperature, we monitored the max temperature while slowing increasing the wattage the heater was running at. There is not a large change until the heater is at around 95 C, at which point the screen began to rise in temperature from 27 C to 28 C. We took measurements of this while the heater was 2.5 and 4.5 inches away from the screen. The irradiance map has a very symmetrical and circular shape, but does not have the ring pattern that we expected. There may be a few reasons for this: there could be some conduction between the two sides of the screen that is causing the pattern to spread further, the heater setup may not be as ideal as it was modeled to be, or there could be a different, unknown issue.

TO DO:

- It would be useful to run a test of the camera in multiple different positions to ensure our conclusion that the camera’s measurements don’t depend on angle or distance (or that these factors are well accounted for in the current temperature calculations) is correct.

- Measure the back of the screen straight on to identify bright spots and possible reasons as to their appearance.

- Recalibrate camera to ensure it is still correct after testing in multiple positions.

- Take another irradiance map of the screen at a higher input power, as well as moving the heater close/further away to try and replicate the COMSOL irradiance maps. It would be useful to also redo the COMSOL modeling at lower powers and variable distances.

Pictures included of full table setup, the heater mount, the heater with Kapton tape attaching the thermocouple as well as FLIR's measured irradiance map.