Leak tested each flange and weld and only found two flanges to have noticeable leaks with the electron multiplier on. These were the turbo pump flange and the RGA flange that connects to the cross. The RGA one is rather new as it has not had a measurable leak before and it was around 2 e-8. We then applied the new sealant to these two flanges as directed by the instructions on the packaging.

Then after waiting a few minutes for the sealant to dry we started the bake. We got the PID controllers set to 120 after many steps and we checked the temperature of the flanges throughout this increase. The flanges never reached 70C with the electronics still left on it. The RGA was left on as well.

The temperature of the flange connecting to the turbo pump after reaching equilibrium is 74 degC. This means that it is safe to proceed with raising the temperature from 120 degC to 150 degC.

Raised the set temperature of the chamber from 120 degC to 150 degC in 15 deg steps.

Checked on the system today.

The flange on the turbo pump has reached an equilibrium temperature of 87 degC when set at 150 degC. While the main body of the chamber has reached an equilibrium temperature of 142 degC.

Checked on the vacuum system today to change the PID controls back to their default values in order to try and get the temperature of the cross in front of the turbo pump higher. Currently it is sitting at 90 degC before changing the controls. While the main body is at 146 degC.

Will update again tomorrow on new equilibrium with the default PID settings.

Checked on the vacuum system and it looks like it will either need to be increased in temperature or baked for a longer time. The main body is at 146C while the cross is at 91C.

Started to cool down the chamber today. Final temperature readings of the chamber were 146C and 91C for the body and cross respectively.

The insulation on the lid of the vacuum chamber has some discoloration and it may be wise to place a sensor closer to this spot in future bakes.

Moved the temperature sensor on the PID controller to one of the switch backs on the lid.

Also started the next bake with both PID controllers set to 150 degC. When leaving the temperature sensors above the chamber read 119 C and 83 C. These sensors are on the chamber wall and flange in front of the turbo pump respectively.

[Dr. Richardson, Aiden]

DO NOT TOUCH ANY VALVES ON THE CHAMBER. THERE IS A PRESSURE DIFFERENTIAL BETWEEN THE RGA LINE, TURBO PUMP LINE AND THE MAIN VOLUME. THE TURBO PUMP WILL BE DESTROYED IF OPENED.

Closed the valves to the turbo pump line and RGA line. Turned the turbo pump back on and saw that the pressure in the RGA Line and Turbo pump line was going down so there was no large leak within that line or with the valves as the main body pressure stayed constant. Then raised the pressure of the main body of the chamber as we suspect the viton o-ring has failed and needs to be changed. The bolts to the lid of the chamber were also removed but the lid was left on.

Then performed a helium leak test on the section of the system that was under vacuum. We found two flanges that had small but significant leaks compared to the others in the lines. The flange connecting the full range gauge to the cross and the flange connecting the stainless steel tube to the valve under the cross. These showed large spikes when sprayed with helium and were then tightened to hopefully fix it. After tightening, the flange under the full range gauge was fixed as the bolts were pretty loose and tightening reduced any spike seen on leak test. The other flange on the SS tube could not be fixed with tightening and it still shows signs of helium leaking through. This flange will need to have its gasket changed to fix this leak. Then left the system where it is in the picture for further changes tomorrow August 11. Again, DO NOT TOUCH THE VALVES ON THE RGA LINE AND TURBO PUMP LINE AS THERE IS A PRESSURE DIFFERENTIAL AND IT WILL DESTROY THE TURBO PUMP IF OPENED.

Note: We also found that the pump under the table had flipped the breaker and needed to be turned back on. This may be something to look into.

[Dr. Richardson, Aiden] Large Update

Removed most of the insulation on the chamber in order to pull back some of the heater tape to get to the flange connecting the bypass line to the valve under the RGA line. Most of the heater tape on the bottom half of the chamber was pulled off and the rest will need to be removed as well in order to place the start of the heater tape on the barrel of the chamber rather than one of the flanges.

Engaged the valve under the RGA line to prevent it from getting more contaminated. Turned off the turbo pump. Turned off the scroll pump. Let the turbo pump sit for a few minutes to let the fans stop. Then leaked the turbo pump volume by turning the knob slowly on top of the turbo. Then proceeded to unscrew the bypass line after done leaking the volume. Replaced the copper gasket and then proceeded to screw it on while maintaining a circular path to ensure equal pressure on the gasket. BEWARE THAT REUSING SILVER PLATED SCREWS HAS A HIGH CHANCE OF STRIPPING THE SCREW AND WILL RESULT IN A LOT OF WORK TO GET THEM OFF. IT IS RECOMMENDED TO USE NEW SILVER SCREWS. HOWEVER WE HAVE NONE LEFT SO DO NOT TRY TO REUSE ANY SCREWS UNTIL WE HAVE SPARES. We were able to use the remaining two spare screws to tighten the flange to a point where it will not tighten anymore.

Then the lid was removed in order to inspect the inside of the chamber and the Viton O-Ring. The chamber had no physical damage and the viton had some visual damage that may correlate to the failure observed during bake 3. Note that some metal chips were found inside of the o-ring groove and needed to be removed. We changed out the o-ring for a new one and placed the old one inside of an anti static bag labeled "Viton O-Ring". Put the lid back on after inspecting for damage and put the bolts on hand tightened. Started to pump down again by turning on the scroll pump first until full range gauge 1 read below 1 torr and then began to turbo pump. The turbo pump was running for 1.5 hours until it plateaued around 3e-4 torr. We then realized the bolts on the lid needed to be tightened more with a wrench. After further tightening the pressure quickly dropped to 6e-6 torr. In the future the bolts should be tightened with a wrench from the begining.

Then proceeded to Helium leak test every weld, flange, and valve. Two of the flanges needed a little more tightening such as the 2 6" flanges. Other than that the only noticeable leak was from the flange just fixed today, however the leak is 10 times less than how it was yesterday and will most likely not hold the chamber back from reaching low 10e-8 torr pressures.

After the bake is done on Saturday it will be cooled down and RGA data will be taken to measure the out gassing rate of the stainless steel fasteners inside the chamber. Then on Tuesday we will plan to vent and open the chamber again to put the macor inside and repeat the another low temp bake and then test the macor early in week 11. Then the next material will be the aluminum mounting hardware for mounting the heaters and that should hopefully be done before the end of week 11 so the heaters can be tested afterwards after being cleaned with vector alpha wipes.

Came into the lab in the morning to check on the chamber heating. I decided to set the PID controllers to 110C rather than 120C as the chamber lid and wall were reading near 140C. With the PID controllers at 110C the chamber lid and wall now read 126C and 132C. Currently the PID controllers are placed on the cross in front of the RGA and the reducing nipple in front of the turbo pump. I believe this is a good equilibrium and will leave the tape on until Saturday when it will be turned off to cool down.

Turned off the heating tape today in anticipation to take more RGA data on Sunday or Monday morning before the meeting.

Did some further testing to determine if it was within reason to increase the temperature of the chamber. I used a thermometer and pulled back some insulation to test many points on the chamber. Mainly focused on the barrel and the bottom lid of the chamber to see if it was possible to increase the temperature of just the PID controller that is powering the bottom half of the chamber.

Found that the barrel of the chamber seems to be hotter than what the sensor is saying, 125 C. Found many points on the barrel that reached 140 C. I believe this is because the sensor is taped on top of the heater tape rather than in between the aluminum and the heater tape.

Also measured many points on the bottom lid as it has the same configuration the top did before it damaged the insulation. It seemed to be consistently at 150 C but I was able to find a couple points that were hotter around 160 C. These hotter spots were most likely the heater folds. There is not much we can do about this as removing the insulation for fixing would required a very invasive procedure to do it safely.

Then moved to the stainless steel tube that connects the RGA and Turbo pump lines. This tube was around 150 C but many points on it were hotter around 160 C. Before another bake I think some of the tape around the tube may need to be pulled back and relocated to avoid damaging insulation while also providing more heat to the main body of the chamber.

Measured a couple more points on the cross that connects the RGA and the full range gauge and found it to be around 130-140 C which means this section could be hotter as the electronics of the full range gauge can reach 150 C.

Over all I believe that the chamber temperature should not be increased in its current state as the bottom lid is a concern with what happened with the top in the second bake. Some optimizations could be made for a fourth bake however. Moving the temperature sensors to be between the heater tape and chamber. Pulling some of the heater tape from the stainless steel tube and relocating it to the main body of the chamber. Moving the PID temperature sensor on the tube to be on the bottom lid or another hotter spot. These are some changes I would make for a fourth bake but maybe this bake could be the last with how the second bake went.

Vacuum Chamber equilibrium temperature for bake 3 are 126 C and 88 C for the chamber wall and turbo pump flange respectively. There were reached with the PID controllers both being set to 150 C.

Also noticed some discoloration around the port insulation. It could be burned from being exposed to the heater tape directly without insulation or it could be that the insulation, which looks much different, is depositing something around the ports.

The turbo pump overheated and the heating tape had to be turned off in order to get the pump back online. It was unusually hot at 52 C. Hottest it got in bake 2 was 38 C.

Pulled off the rest of the heater tape along with the aluminum tape left behind. The aluminum tape adhesive left behind a ton of junk on the walls of the chamber. This is probably due to excessive heating. In order to get the adhesive off I sprayed a vector alpha wipe with acetone and wiped down the walls. This took a lot of acetone to get it off.

When removing some of the aluminum tape I noticed small sections that seemed to have been melted to the silicone part of the heater tape and would have been damaging to try and forcefully remove it.

The heater tape is now ready to be put on again but now with the start of the tape placed on the other side so that the PID controllers can be placed on the shelf above the chamber and be seen outside of the curtain.

Put the heating tape back on and made sure to have 4 coils around the barrel of the chamber. To make this happen I did not put any heater tape on the ports but made sure to place some of the heater no more than 1 inch away from the ports. Also re-placed some of the heating sensors. For the PID controllers there is one sensor placed on the lid and one sensor placed on the barrel. For the temperature alarms one sensor was placed near the flange of the turbo pump and another placed on the cross in the RGA line. Note that all four of these sensors were placed under the heating tape compared to the last few bakes where they were on top.

The insulation was also put back on and now the chamber should be ready for a low temperature bake after some RGA data is taken before for comparison.

Took more data today and the chamber and elements are showing an even lower HC level than we have gotten before. It is safe to say that the elements are not contaminated and out gassing HC into the chamber.

Today, I was able to make some adjustments to the FLIR camera angle, suggested by Dr. Richardson, and we got small possible movements keeping the same pattern in the shapes of the triangles. I have attached photos below. I was able to move left and right as well as up and down and it worked in four points that I marked on the table.

The only problem is that it only worked on a part of the screen, if I try to place it farther to the right or to the left, we are back to the same problem as yesterday.

[Luis, Luke, Tyler]

Vacuum chamber parts were finally received and assembled. After whipping down the parts, the blank was removed from the reducing cross. Then, the zero-length reducer was attached. Lastly, we installed the T that had the argon leak and RGA. The final pump down showed signs of an improved seal since the pressure dropped quite fast. This pressure is well bellow the limit required to use the RGA, argon test leak could be performed some time next week.

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.