[Luis, Luke]

RGA Volume: T = 21°C, P = 1.74e-9 Torr
Main Volume: T = 22°C, P = 5.60e-9 Torr

We performed an RGA scan of the system. As we can see, we met cleanliness standards. The S/N ratio was roughly calculated and it is about 100. I will update the code to make this calculation and to have it displayed on the plot in the next scan we perform.

After this, we closed the RGA to the main volume valve, degassed the filament, and after the pressure came down to what it was initially, we reopened the valve. After the degassing, we took another scan. The overlaid plots are attached below.

The noise floor seemed to be about the same. I will take another scan tomorrow to verify whether it was the same or if the system just needed a little more time to be completely clean.

[Luis]

RGA Volume: T = 23°C, P = 1.71e-9 Torr
Main Volume: T = 22°C, P = 5.71e-9 Torr

On 12/13 I took another RGA scan to verify the state of the vacuum system and to see whether the degassing of the filament had worked. The results of the scan shows that we did get an overall improvement of the noise levels, though we still have some peaks that are higher than the rest.

Also, while I was around, I transferred the Viton O-rings to a bag and labeled it properly. They are ready to be put into the clean room.

[Luis, Luke]

The MR material was placed in the vacuum chamber following standard procedures to ensure the vacuum remained as clean as possible. During this process, we only opened the main volume while keeping the gate valve between the two volumes closed to maintain the UHV in the RGA section.

An RGA scan was taken before this process, this will be used to compare the state of the vacuum with the sample inside to determine whether the MR material is vacuum compatible.

[Luis]

The vacuum system is being baked. I disconnected the digital gages and the magnets, opened the Ar leak and started the bake by taking the temperature from 60C-90C-125C waiting about 15-20 minutes between each interval. The RGA electronics were left on since the temperature of the flange was 36.6C (bellow the 60C threshold)

I have begun the (hopefully) final RIN measurements at 3:30 PM today. If you need to go into the cleanroom at any time between now and Sunday (the 22nd), please do not touch the FROSTI, the Red Pitaya, the photodetectors, or any of the wiring.

The vacuum chamber has stopped baking. 

Current state as of 11:40, 12/19/2024:

The gate valve is open, and the filament of the RGA is on.

The temperatures were steady at:

PID right: barrel upper: 129°C,  RGA volume: 125°C

PID left: barrel lower: 125°C, Lid: 114°C

The RGA flange was 37°C

Cleanroom was 26°C

Note the upper barrel was very close to the emergency shut off temp of 130°C. In the future we may want to either rewire some of the heating tape or lower the set temperature of the right PID controller.

Luis and I are planning on taking an RGA scan of the MR on Sunday before the campus shuts down for the holidays.

[Luis, Luke]

RGA Volume: T = 23°C, P = 3.0e-9 Torr
Main Volume: T = 22°C, P = 9.90e-9 Torr

After letting the vacuum cool down for a couple days, we reattached the magnets and sensors, then we performed a RGA scan of the vacuum system, now containing the MR sample. The results are attached below. Something to notice is that we are technically not under UHV, though Luke and I believe the reading of the sensor is not completely accurate since it was still coming to a steady state, further test will be performed when the physics building is open again.

[Luis, Luke]

RGA Volume: T = 22°C, P = 2.10e-9 Torr
Main Volume: T = 21°C, P = 5.71e-9 Torr

Measurements of the current state of the vacuum systems were taken today, now that the system had reached UHV status, the results are attached bellow. The first plot overlays the data of the empty chamber taken on 12/16/24 before inserting the MR material, and the data of the system today, with the MR inside. The second plot displays the S/N Ratio of the system. The last plot displays the data of the system with the Ar leak open and closed. Notice that it is common for the Ar leak close data to fail due to the calculation of the gas flux per unit ion current, which is dependent on the Ar peak.

Attached below are updated plots for the FROSTI RIN measurements for Jan 14 group meeting.

On Tuesday, we prepared the FROSTI for disassembly in anticipation of the APS filming that is set to take place in the labs. The FROSTI has been unbolted from the optical table in the cleanroom, with its wires weighted down and the majority of its screws removed to ensure an easy removal of the reflectors during the filming process.

On Tuesday (Jan 21), we took the FROSTI apart in front of a filming crew. It was a success! The footage is going to be used in an APS video detailing the experimental cosmology research conducted in the department.

The FROSTI reflectors, heater elements, and legs were all bagged separately and a currently being stored in the cleanroom. If you need to do any work in there, please be mindful of these parts. The elements are currently on the shelf above the optical table, and the reflectors are placed on the table in the back corner.

Here is a quick update on some of the things I have been working on regarding my project. 

[Ma, Cece, Luke, Mary, Shane]

On Friday (Jan 24), we installed the heater elements on the stand. The heater elements are arranged from 1 to 8, oriented from right to left as shown in Attachment 1. Each wire has been labeled according to its corresponding element number and type (e.g., RTD connections, heater connections).

Note: We currently do not have enough PEEK zip ties, so standard zip ties have been used temporarily. These must be replaced with PEEK zip ties before the setup is placed in the vacuum chamber.

[Ma]

Installed all the pins to the peek DB 25 connectors

[Ma] Wed 1/29/2025

No short circuit between heater element ✓

No short circuit to ground on any pin ✓

No short circuit between connectors ✓

[Ma]

changed all zip ties to peek zip ties, and grouped wires together. The setup is ready to go into the chamber.

[Luis, Ma]

Feb/10/25 4:00pm

Bake was stopped.

[Luis]

Feb/11/25 9:30am

Pressure gages were connected.

[Luis, Luke, Ma]

February 12, 2025 - 4:00 PM

We performed an RGA scan with the vacuum system containing the heater elements. The results are attached below.

As we can see, we are not yet under cleanliness standards. The passing threshold is 4 × 10⁻¹⁰, and we are currently measuring nearly double this value. We will continue performing scans to monitor any changes in these readings.

Over the last couple weeks I have been working on finding the optimal position of the ringheater's thermal profile. 

Today I would like to give an update of where I am at and my next steps.

Using the python COMSOL interface I have been able to run and save deformation data sweeping through a great deal of potential combinations of widths and positions.

I then calculated their zernike coefficients and using a very simple "quality" function (02 - (40)*10 - (4-4)*10), where 02 stands for the zernike mode of quadratic deformation, I was able to generate a heat map of comparing the "quality" verses the width and position used. 

Seen below are four plots. The first is simply the 02 coefficient of the decomposition followed by the negative of 40 and 4-4 then the "quality."

This 'quality' function was an arbitrary choice on my part. I believe that my next step would either be defining a more useful function or using finesse to model the actual effects of this surface deformation.

[Ma, Pooyan, Tyler]

On Friday, we connected the vacuum chamber with the Cymac.

https://docs.google.com/presentation/d/1WiV2VqS0BzXNCK6VYYQ-Ty8xlHnzXatQaFbMf1-0rsY/edit?usp=sharing

Below is a preview of the final RIN figure that will be included in the FROSTI instrument paper. A quick summary of what is shown below:

The original RIN CSD measurement is shown on the top panel in red. Frequency bins that exhibit external electronics noise (ex. ADC, photodetector noise, etc.) are identified and shaded in gray. These noisy bins are then excluded from the dataset before beginning the next step in the analysis process: rebinning. Here, the resolution of the spectrum can be changed by averaging frequency bins together within a specified interval, with the goal of pushing the measurement curve closer to the A+ requirement shown in the figure. For demonstration below, the spectrum goes from a resolution of ~0.93 Hz to 14.90 Hz.

Debugging update for vac system serial communications: we were able to successfully connect the smaller turbo pump to the Varian (manufacturer) software today by plugging the controller db9 directly into spica, and verified that the pump was able to send and receive information. Still no success on communication with the larger pump via python serial code, though. Issue potentially lies in the pinout mapping of the connectors, as the pinouts we'd been using work successfully for the small pump which only requires 3 connections (RXD, TXD, GND), but the large pump may require more. Tried to test this on the big pump by keeping the pinout setup for the small pump, and incrementally adding the remaining 6 connections on a one to one scale (Pin 1 matched to Pin 1, etc) between the controller DB9 and the field DB9 connected to the IOLAN ethernet cable. After each new connection was added, I retried running the serial connection code. None of the additional connections yielded any results, and the large pump remained unable to connect through the code. Next step is further looking into documentation on the pinouts to see if the large pump requires a different connection setup than the small pump.

[Ma, Luis]

February 20, 2025 - 3:30 PM

Ma performed an RGA scan with the vacuum system containing the heater elements. The results are attached below.

As we can see, we are not yet under cleanliness standards. The passing threshold is 4 × 10⁻¹⁰, we are very close to it.

These are some plots:

The first shows the convergence of the 02 mode reducing the size of the mesh. The second shows the the numerical error of the zernike.

The first is found by sweeping a parameter that changes the size of the mesh. The HR surface was set to half a cm for all values.

The second by taking the inner product of a zernike mode with its self and calculating its deviation from pi for varying fineness of the mesh.

[Ma, Luis]

February 24, 2025 - 1:00PM

Ma performed an RGA scan with the vacuum system containing the heater elements. The results are attached below.

1424039912.625576 2025/02/19 22:38:14 UTC Time start

24V 2.8A right after start all 8 elements

1424044804.902443 2025/02/19 23:59:46 UTC Time stop

24V 1.8A right before stop all 8 elements

0.1A right before start and right after stop

note: turned on briefly to check current right before stop

2/20 RGA Scan

spikes??

1424129207.857777 2025/02/20 23:26:29 UTC Time start

24V 2.9A right after start all 8 elements

1424140789.856096 2025/02/21 02:39:31 UTC Time stop

24V 1.7A right before stop all 8 elements

0.1A right before start and right after stop

2025/02/21 02:43:19 UTC

Main chamber pressure: 1.54e-8

RGA chamber pressure:5.06e-9

spikes are due to loose connection between connectors.

1424210410.173863 2025/02/21 21:59:52 UTC Time start

24V 2.9A right after start all 8 elements

1424218357.96404 2025/02/22 00:12:19 UTC Time stop

24V 1.7A right before stop all 8 elements

each elements: 0.3A (0.2A increment)(all)

0.1A right before start and right before stop

2/24 RGA Scan

1424467918.129082 2025/02/24 21:31:40 UTC Time start

12V 2A right after start all 8 elements

1424478936.635821 2025/02/25 00:35:18 UTC Time stop

12V 1.6A right before stop all 8 elements

each elements: 0.4A (0.2A increment)(all)

0.2A right before start

rise time: A(1-exp(-t/tau))+B

fall time: Aexp(-t/tau) +B

1424564097.243212 2025/02/26 00:14:39 UTC Time start

12V 2A right after start all 8 elements

1424564478.079428 2025/02/26 00:21:00 UTC Time stop

12V 1.8A right before stop all 8 elements

1424564832.211584 2025/02/26 00:26:54 UTC Time start

12V 1.9A right after start all 8 elements

1424565208.359935 2025/02/26 00:33:10 UTC Time stop

12V 1.8A right before stop all 8 elements

1424565573.565066 2025/02/26 00:39:15 UTC Time start

12V 1.8A right after start all 8 elements

1424565931.242394 2025/02/26 00:45:13 UTC Time stop

12V 1.7A right before stop all 8 elements

1424566292.67104 2025/02/26 00:51:14 UTC Time start

12V 1.8A right after start all 8 elements

1424566648.619952 2025/02/26 00:57:10 UTC Time stop

12V 1.7A right before stop all 8 elements

1424566996.312246 2025/02/26 01:02:58 UTC Time start

12V 1.8A right after start all 8 elements

1424567381.748943 2025/02/26 01:09:23 UTC Time stop

12V 1.7A right before stop all 8 elements

1424567756.528736 2025/02/26 01:15:38 UTC Time start

12V 1.7A right after start all 8 elements

0.2A right before start

spikes!?

1424643001.864687 2025/02/26 22:09:43 UTC

change c_0(VEXC0 & VCXC0) to 2V (why is it on 5V ?)

2025/02/26 22:18:51 UTC

Main chamber pressure:5.92e-9

RGA chamber pressure:1.98e-9

1424650528.240947 2025/02/27 00:15:10 UTC Time start (increase voltage)

24V 2.1A right after start all 8 elements

disconnect and reconnect (exc 1-4)(out 9-12) & (exc 5-8)(out 13-16)

2025/02/27 19:34:26 UTC

Main chamber pressure:1.34e-8

RGA chamber pressure:4.33e-9

Main chamber temp: 29

RGA chamber temp:29

2025/02/28 18:02:29 UTC

Main chamber pressure:1.05e-8

RGA chamber pressure:3.53e-9

Main chamber temp: 29

RGA chamber temp:30

1424801097.374902 2025/02/28 18:04:39 UTC Time stop

24V 1.8A right before stop all 8 elements

0.1A right after stop

1424827460.71372 2025/03/01 01:24:02 UTC Time start

24V 2.9A right after start all 8 elements

0.1A right before start

2025/03/01 01:25:34 UTC

Main chamber pressure:5.98e-9

RGA chamber pressure:2.06e-9

Main chamber temp:27

RGA chamber temp:27

2025/03/03 20:28:03 UTC

Main chamber pressure:7.8e-9

RGA chamber pressure:2.64e-9

Main chamber temp:27

RGA chamber temp:27

Spikes Appear Again, need to address it systematically.

Power on and off before reaching steady state ✔

At 12V, the rise and fall time of heater elements are different from 24V.

Initial guess is due to temperature in the chamber. However, it does not seem to be the case, 24V with 30c have the same hall time as 24V at lower temperature.

Attached are some graphs for rise and fall time

After a weekend of powering on, the main chamber pressure stabilized in the UHV region.

Temperature in the chamber seems also not to change.

[Shane, Jon]

Update on the serial interfacing with the vacuum system: both turbo pumps are now able to successfully communicate through the code. The older pump, for unknown reasons, required a newer version of the communication syntax (despite the newer, small pump being able to communicate fine with the old communication format). We have also confirmed that the newer pump works with this new format as well. Next step is interfacing the pressure gauge.

[Shane, Jon]

Continue investigation in the spikes

Pulsed ADC with a function generator and find no spikes. Rules out ADC for causing the spikes

Loopback test that bypasses the FROSTI Chassis shows spikes (spikes happened on all channels at the same time)

Next step is to bypass the AI Chassis to find the source of the spikes

Upon final review of the FROSTI analysis included in the (hopefully) soon-to-be submitted instrument paper, I've made some adjustments to the reflectivity analysis that estimates the amount of power delivered to the test mass by the FROSTI. Initially, as detailed in elog 447, the delivered power was approximated to be 12.6 W (later adjusted to 12.9 W), with roughly 18% of this power being reflected by the test mass. After some final adjustments, this value now is closer to 12.0 W, with 10.2 W absorbed (15% power reflection). Below is a table showing the updated values for the FROSTI prototype tests:

The result from AI Chassis bypass test showed that the AI Chassis may be the problem. There are no spikes from DAC's direct output.

All chassis except timing chassis are turned off. Power supplies for 24V, 18V, and -18V are turned off

The AI chassis has been taken out of the rack for further inspection

https://dcc.ligo.org/LIGO-E2300117

https://dcc.ligo.org/cgi-bin/private/DocDB/ShowDocument?.submit=Identifier&docid=D2300124&version=

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.