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.

Update Slides

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)

Power point slides

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slides

[Luke, Luis, Michael]

cleaning cleanroom and particle count

• 8:30 am: started particle count
  • zone 3:
    • 0.3 u: 1195
    • 0.5 u: 177
    • 1.0 u: 132
• zone 4:
  • 0.3 u: 619
  • 0.5 u: 0
  • 1.0 u: 0
• 9:00 am: began surface check and wipedown, including softwalls
• 9:35 am: started vacuuming the floor
• 9:43 am: finished vacuuming the floor
• 9:45 am: started mopping the floor
• 9:55 am: finished mopping the floor
• 9:56 am: started cleaning the buckets
• 10:00 am: started mopping with IPA wipes
• 10:05 am: finished mopping with IPA wipes
• 10:20m: started particle count
  • zone 3:
    • 0.3 u: 2213
    • 0.5 u: 398
    • 1.0 u: 0
• zone 4:
  • 0.3 u: 1150
  • 0.5 u: 177
  • 1.0 u: 44

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]

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)

[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]

We couldn't access the bake log on the wiki. (see attached) So we looked in the documentation provided on the DCC to find at what temperature to bake the Viton O-rings. We found that we should bake Viton at 180°C for 24 hours. 

So we sonic-washed the O-rings, dried them, and then put them in the oven set to the following:

100°C in 15 minutes

100°C for 30 minutes

180°C in 30 minutes

180°C for 24 hours

30°C in 2 hours

Other things of note:

We refilled the water container as it was running out.

The nitrogen used to dry the clean and baked objects is now critically low.

The helium used in leak testing is also quite low (~400 psi).

Regarding the vacuum chamber:

I reattached the pressure gauges to the chamber and gave them about an hour to stabilize. They read out main 8.7e-9, RGA 2.6e-9. Please note these pressures should lower more as we only stopped baking on Saturday afternoon. 

[Luke, Tyler, Cynthia, Shane, Michael]

Summary of Cleaning Activities:

We began cleaning Room 1119 at 2:00 PM.

At 2:30 PM, we moved to Room 1129 and continued cleaning.

Cleaning tasks included wiping down dust-collecting surfaces and vacuuming the floors.

Once the labs were clean, we proceeded to the cleanroom. 

• Wiping down surfaces and soft walls
• Vacuuming, mopping the floor, and finishing with IPA wipes

Particle Count Measurements:

• Pre-cleaning (2:30 PM):
  • Zone 3:
    • 0.3 µm: 973
    • 0.5 µm: 354
    • 1.0 µm: 132
  • Zone 4:
    • 0.3 µm: 486
    • 0.5 µm: 177
    • 1.0 µm: 0
• Post-cleaning (4:10 PM):
  • Zone 3:
    • 0.3 µm: 619
    • 0.5 µm: 132
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 397
    • 0.5 µm: 0
    • 1.0 µm: 0

[Luke, Liu]

Over the winter break I have been working on this desmos toy model of the Frosti. There are still a few rough spots but I belive that it is a good visual representation of a 2D slice of the frosti. 

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

[Luke, Cece, Luis]

Particle Count Measurements:

• Pre-cleaning (12:15 PM):
  • Zone 3:
    • 0.3 µm: 1325
    • 0.5 µm: 265
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 618
    • 0.5 µm: 132
    • 1.0 µm: 44

• Started Cleaning (3:20 pm)
• Finished Cleaning (4:20 pm)

• Post-cleaning (4:35 PM):
  • Zone 3:
    • 0.3 µm: 1106
    • 0.5 µm: 221
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 530
    • 0.5 µm: 44
    • 1.0 µm: 0

[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. 

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.

[Luke, Mary, Luis]

Particle Count Measurements:

• Pre-cleaning (8:40 am):
  • Zone 3:
    • 0.3 µm: 441
    • 0.5 µm: 44
    • 1.0 µm: 0
  • Zone 4:
    • 0.3 µm: 353
    • 0.5 µm: 176
    • 1.0 µm: 44

• Started Cleaning (3:16 pm)
• Finished Cleaning (4:10 pm)

• Post-cleaning (4:15 pm):
  • Zone 3:
    • 0.3 µm: 574
    • 0.5 µm: 265
    • 1.0 µm: 132
  • Zone 4:
    • 0.3 µm: 177
    • 0.5 µm: 44
    • 1.0 µm: 0

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.

I have redone the width and location optimization with a 40kg test mass. This was to see where the nominal ring heater would fall in this optimization map see attached.

There are two concerns I have with this modeling:

1. I am using normalized power only imparting 1W, which may effect the single pass scattering used for optimization.
2. I am only looking at the surface deformation and I believe that looking at OPD may also be something that is important to consider. 

Note z_RH is measured from the HR surface and w_RH is the half width of the target plane

I have created two more plots. One on the transmitted power for a specific configuration. This was done by taking the product of the efficiency and the power released by surface area of the source plane for a configuration assuming it is at 300C. The second is a plot of how close the reflector is to the test mass I have included a contour line at 2mm the nominal proximity constraint. Both of these plots are generated for a 2cm wide target plane.

Somethings of note: Because the proximity requires no modeling and can be determined purely mathematically it is easy to re-generate this plot of other target widths. If you increase the target width the proximity contour moves upward and downwards if reduced.

We will be configuring the RGA line to remove the spherical cube from the system. Currently our plan for the new design is to connect a 4.5" to 2.75" Reducing Cross to the gate valve on the vacuum system. It will be orientated vertically with the turbo pump on top coming off the end will be a 90 deg elbow. On the bottom there will be a 4.5" to 2.75" Zero length reducer attached to that will be a Tee on one side the pressure sensor and the other the RGA. Connected to the elbow will be the calibrated leak. 

The only parts not readily available are the ZLR and the 2.75" gaskets

[ Luke, Cynthia, Michael, Xuesi, Anthony ]

Started work around 12:45

We vented the chamber first and once it reached atmospheric pressure we started taking apart the RGA line.

We removed the parts in this order: Calibrated leak, RGA, Pressure gauge, 2.75" Blank on Tee, 2.75" Tee, all 1.33" Blanks on the cube, 4.5" feed through port, and finally the cube. Everything went smoothly after every part was taken off we covered the ends in Aluminum foil to maintain cleanliness. 

We then started the assembly of the new line. The parts were added in this order: Reducing cross, ZLR, Tee, Cal leak, RGA, 90 deg Elbow, and Pressure sensor.

We left off the Turbo pump as of now because we weren't able to find a 1" post not in use and we didn't want to put too much weight on the cross. We also noticed that the RGA might not fit on its probes because of a slight tilt to the cross and by extension the Tee. If this ends up being a problem we might need to remove all the parts connected to the cross so that we can reposition it so that the 2.75" rotating flange is connected to the gate valve.

Ended work around 4:00

[ Luke, Jon ]

Started work at 11:00

As mentioned in my previous post the RGA was not clearing the table because of a tilt in the cross. So I removed the 90 deg elbow, loosened the bolt securing the Tee to the ZLR, and removed the cross from the gate valve. I then spun around the Tee on the bottom so that the cal leak would be pointing in the right direction and connected the rotating 2.75" flange of the cross to the gate valve. I then added the small turbo pump to the top of the cross. 

Then with the help of Dr. Richardson, we made some adjustments to how the Tee was oriented with respect to the cross and how the cross was with respect to the table. So that the cal leak and RGA would fit on the table. After that we made some changes to the bolting of the ZLR to reducing cross replacing the 2.00" bolts and nuts with 1.75" bolts and nut plates. We did face some difficulty with half of the 2.00" bolts which required a bit of torque to get them out. 

Finished work at 2:20 

Things to do:

Before we start pumping down the system again Dr. Richardson wanted two other changes to be made. To replace the 2.75" to 1.33" conical reducer with a zero length reducer. He also wants the bolts that hold the main turbo pump to be replaced with nut plates. 

I plan on starting this work on Friday (7/12) before pumping down over the weekend

After the feedback from last meeting and Liu's help narrowing down what I should do to improve the model. I made some changes: First with Liu's help I made the proportions of the test mass and ring heater much more reasonable and parametrized by constants. Second from Cao's paper "FROSTI Nonimaging Reflector Design" Liu showed me what I should do to define the elliptical mirrors. Third during Friday's modeling/programming meeting walked me through getting the different irradiance plots to work. 

Today, I borrowed a bolt extractor drill bit from the machine shop to remove some stuck bolts from the zlr. Before starting, I laid down a sheet of aluminum foil on the work table and wiped down all the tools I was going to use. I began by drilling a small pilot hole and then enlarged it with a 5/32 drill bit. However, when I attempted to use the bolt extractor, it didn't grip the bolt effectively. Our bolts were too seized, causing the extractor bit to repeatedly slip instead of gaining traction.

[Luke, Luis, Jon, Tyler]

On the 22nd Dr. Richardson showed Luis, Tyler and I how to preform a leak test with the RGA. We did the initiall test and found a few leaks two were particuarly bad highlighted in orenge below. To try and remidy this we planned on replacing the copper gaskests on the leaking flanges. We then began taking the two problem flanges off, but seven of the eight bolts holding on the turbo pump were over tightened and had seized. So after we got them off we postponed the rest of the work to the next day.

On the 23nd Luis and I reattached the badly leaking flanges with new copper gaskets. We then preformed the Helium leak test with the RGA. As seen in the table below we weren't able to majorly changed the leaks in the two flanges.

[Luke, Tyler]

On the 27th Tyler and I ran the RGA leak test again with the electron multiplier on. These were the leaks we measured. The chamber's overall pressure was at ~6e-8 torr.