After meeting and discussing the current state of our work with Prof. Fulda a few weeks ago, we have decided that the best next step for the gtrace project is its integration into finesse work. Our first step towards this integration involved creating a sequential beam trace in contrast to the previous non sequential gtrace simulations. A sequential beam trace not only allows for faster runtimes of the simulation (<1 second) but also allows for more direct reading of certain beam parameters (beam size, gouy phase, and angle of incidence). The sequential model was created alongside a yaml output which provides values of parameters, now including the angle of incidence on a mirror.

Last Monday, Pooyan gave a report to the Cosmic Explorer optical design team on the current state of our project and the ultimate goal of our work. During the same meeting another group working in the optical design team presented their own work with gtrace and optical design, focusing more on optimization of parameters based on desired beam sizes at each mirror. It might be a good idea to begin attempting to bring our individual projects together to allow for collaboration and further developments.

Currently, only the crab1 layout has a sequential trace model. Pooyan is currently working on creating a finesse model for crab1 to serve as a proof of concept for how gtrace could be integrated with finesse by providing useful values such as angles of incidence.

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.

[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.

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.

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

After Jon's comment yesterday that some of the connection did not seem to have good metal-metal contact, in particular the gate valve connection, I went through the ConFlat connections today and retighten them. I found a lot of the CF connections are not particularly tightened and there were a lot of range left that can be tightened with the wrench. After re-tightening, the copper gaskets are not visible anymore. For example, see the attached images for the difference before and after tightening.

Note for future installation of CF

• After tightening the bolts/ screws in jumping order (to provide uniform torque) and there is resistance appearing in further tightening, start going through each screw/ bolts in a direction, each time applying a small torque until it resists to further tightened
• After each time going all the bolts/ screw and returning to the starting point, one will find they can further tighten the screws/ bolts. Repeat the process until no further tightening can be achieved
• The copper gasket should not be clearly visible at the connection

• I collected data to plot a calibration with the heater. I took measurements with current and temperature (the thermocouple - thermometer) to compare with the FLIR measurements.
• I made a plot with this data and we can see how temperature vs current behaves. Note: This data I measured manually.

• I noticed that these measurements have some issues with the weather on different days. We can see in the photo attached below how different the temperatures are on different days, I took the data with the same procedure every day, but we can see the differences between them.
• To Do: I will do a new data collection using FLIR and thermocouple at the same time to plot comparison between both.

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.

Luis and Aiden vented the chamber today. We closed off the RGA section and then proceeded to open the the vent on the main body after turning off the turbo and backing pump. We then opened the lid and placed in all the stainless steel hardware that will be used in evaluating the FROSTI optics and heater elements. We also inspected the weldments before closing it up. Check the clean and bake data base where there is now a new section outlining the parts in each test. We then closed the lid, tightened the bolts, turned the backing pump back on and let the pressure drop until it was below 1e-1 torr. Then turned the turbo pump back on and after a few hours the pressure was back down to 4.16e-7 torr. The RGA was turned off during all of this and was turned back on when done even though we closed both valves to keep the RGA volume under vacuum.

Installed a Synology NAS server (Synology RackStation RS1221) in lab room 1129, with host name “scribe” and ip “192.168.1.17”. It is mounted on the rack and each of its 8 storage bays has a 2TB SSD disk. It will be used to set up automated backups of all the lab machines (e.g., chimay, logrus, megatron).

One shared storage is set on it with SHR-2 as its RAID type. It can tolerate the failure of two disks and has 10.4TB of total capacity. 

We can use both rsync and dd to create backups of the system. A suggested backup schedule could be daily rsync backups and bi-weekly disk snapshots using dd. 

[Luke, Luis]

Update of current state of vacuum chamber

Current temp: 24°C

Current pressure: Main 1.77e-8, RGA 5.3e-9 [torr] (Gate valve open)

Summary of recent work-->

To try and reduce the leak in the turbo pump by reducing cross-connection, we replaced the copper gasket. This made no improvement to the leaks.

Initially: 1.9e-9 --->

Left side: 1.33e-9, Right side: 3.37e-9 (Gate valve open)

This is still a significant leak. We have tried to tighten the bolts further, but they are as tight as reasonably possible. 

Things of note: While examining the knife edges, we found some very slight imperfections on the reducing cross's flange as seen in 474. This could be the source of our leak. We have replaced this gasket 1-2 times already and consistently have a slight leak. This imperfection is on the right side of the flange, which would be consistent with the measurements above. 

Unless we want to use the liquid sealant or replace the gasket with an annealed gasket, we could try baking the system again, as this allowed us to reach UHV in the main volume before. It also allowed us to pass the RGA scan, which we are currently failing. (see attached)

Drawings and CAD models of the straight-edge designs are exported, and are visualized in SOLIDWORKS. Two are attached. One is a single edge of the evenly spaced polygon design with 16 edges, and the other is the 8x2 design, with two neighboring edges grouped together to replace the original single curved heater.

For the straight edge design in COMSOL, ray power detectors were placed at the heater's front surface. The irradiance is shown in figure. The amount of light rays deposited back to the heater is small when close to the center, where it is closer to the original ring. The ray power increases as we move further away from the center toward the edges. In addition, the total power integrated at the heater's front surfaces is about 21% of the original heater's emitted power. This could account for the power efficiency difference between the straight edge design and the ring design, as shown in plot for instance.

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.

Update Slides

[Luke, Luis]

The vacuum chamber is currently baking. 

We stepped up to 125°C by increments of 30°C starting at 60°C. Everything went fine. After about 20 minutes of the PID controllers being set to 125°C, the flange closest to the RGA was 38°C, so we left it connected. 

Current state as of 4:15:

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

The temperatures are as follows:

PID right barrel upper: 105°C,  RGA volume: 125°C

PID left barrel lower: 125°C, Lid: 82°C

The lower temperatures should climb as the whole system heats up. 

I will come in Saturday afternoon to turn them off so that we can look at the pressures on Monday. 

[Luke, Luis]

The vacuum chamber is currently baking. 

We stepped up to 120°C by increments of 30°C starting at 60°C. We took about an hour break at 90°C to let the temperatures equilibrate.  

Current state as of 12:20:

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

The temperatures are as follows:

PID right barrel upper: 113°C,  RGA volume: 120°C

PID left barrel lower: 121°C, Lid: 114°C

The lower temperatures should climb as the whole system heats up. 

Fuse replacement

• Replace blown 10A fuse in ucontroller outside cleanroom
• Replace 10 A fuse in main power connection slot of the controller unit inside cleanroom
• Pamella wiped down unit outside cleanroom.
• Controller units turned on and temperature setpoint set to be 80 deg C
• Temperature settle in approx. 15 minutes(as recorded by the RTD). No problems with fuses observed
• Recording of pressure gauges (in Torr) :
  1. Before turning heater on :
     1. Gauge 1(main chamber): 3.73E-7
     2. Gauge 2(RGA line): 3.65E-7
     3. Gauge 3(Pump line): 3.8E-4
  2. After 15 minutes :
     1. Gauge 1(main chamber): 7.07E-7
     2. Gauge 2(RGA line): 6.12E-7
     3. Gauge 3(Pump line): 3.8E-4
• Reduce setpoint temperature to 60 deg C due to Pinrani gauge (Gauge 3) temperature limit
• Upon returned to lab to reduce temperature (35 minutes after turned on):
  1. Gauge 1(main chamber): 1.22E-6
  2. Gauge 2(RGA line): 9.98E-7
  3. Gauge 3(Pump line): 3.8E-4
• Once temperature has settled to 60 C (approx 20 mins after changing setpoint), pressure readout showed:
  1. Gauge 1(main chamber): 1.37E-6
  2. Gauge 2(RGA line): 1.10E-6
  3. Gauge 3(Pump line): 3.8E-4
• Heater left on for the whole afternoon, pressure readout upon returning to lab at 5:30 pm:
  1. Gauge 1(main chamber): 3.43E-6
  2. Gauge 2(RGA line): 2.61E-6
  3. Gauge 3(Pump line): 3.8E-4

• Today I tried get data the heater with the black screen but doesn't looks possible have just one "energy" point straight to FLIR camera. Tyler and I tried different current and temperatures but keep very bad data. I attached a snap below.
• I attached a photo about the new setup below. The FLIR is in the most close point possible/safety with the heater. The heater is very close to the black wall but is not touch the screen so is safety.

Attached is a brief recap PDF file. A video file showing separate HOMs plots for the cavity scan with ETM08 surface map is also attached.

The codes are available at https://git.ligo.org/uc_riverside/hom-rh/-/tree/main/SIS

Ringheater Update

If the link does not work here is the file.

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.

Power point slides

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

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.