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.

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.

[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.

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.

Came in to take RGA data and found the turbo pump drawing .38 Amps. This was much higher than what it was on Friday. I investigated and found that the breaker had flipped controlling the power strip that the scroll pump was on. The scroll pump was thus not running. I flipped the breaker back and turned the scroll pump back on. I do not know if this will be a reoccurring problem as this has happened before, or if this was due to the storm. Either way the scroll pump is running and the turbo pump is now only drawing .18 Amps at 31 C.

Below are the graphs for the RGA scan that I took before starting bake 4. I have not overlaid them yet so the first one is for Argon leak closed and the second is the Argon leak open. It seems that the chamber had gotten dirtier since the leak and there is still a lot of water left in the chamber. I assume the water will go away after the low temp bake but the HC count may not go down without a longer baker. I also measured the pressure before starting the bake and it was 4.16 e-7 and 3.31 e-7 torr for t he main body volume and RGA volume respectively.

When starting the bake I noticed that the temperature sensor placed on the cross in the RGA volume was reading 40 C hotter that what the PID controller was reading for the lid. I had to remove some of the heater tape from the cross as it was way too hot compared to the lid. After removing the second strip across the cross it is still much hotter than most parts due to it being such a small part compared to the large lid. I hope that after a little bit of equilibration time that the difference between these numbers will go down. Both PID controllers were set to 120 C. The RGA cross was reading 130 C and the Turbo pump cross was reading 76 C.

Continued tightening bolts on the turbo pump and 6"-8" reducer to reduce the leak. The final leak test values for the turbo pump flange was 3.0 e-9 and the other 6"-8" reducer flange was 4.0 e-9.

We will continue to let it pump down as the screws could not be tightened anymore. Looks like new gaskets will be needed to reduce the leaking on these flanges.

Took some RGA data when we came into the room. The pressure of the chamber was 8.63e-8 Torr before turning on the RGA filament. We saw the usual spike in pressure when the filament was initially turned on. Took some data and saw that the chamber was definitely dirtier since the vacuum upgrade. See figures below.

Put the heater tape back onto the section that was removed. We may need to rearrange the heater tape again as there was not much heater tape to go around the upgraded section. We also tried to get some of the extra insulation around this section and we able to get some on around the 6-8 inch reducer.

We then took off the electronics for the gauges and the RGA, added the new extension cords to the PID controllers, and then started bake 6 which will go to 120 degC and stay that way until most likely Monday. The pressure before starting the bake was 8.28e-8 Torr.

[Aiden, Luis]

Tested every weld and flange to find leaks. Only found that the flange on the turbo pump and reducing nipple was still at 2e-9 torr on the leak. The chamber still rose in pressure when the two gate valves were closed but no noticeable leak could be found on the lid or welds.

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.

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.

Took some RGA data of the chamber after it has been cooling down. I do not believe that this data accurately shows the HC levels in the chamber as the pressure is still above where it was at before the bake and was still falling. I believe more time is needed to let the pressure fall and for the RGA filament to remain on to return to a point where the data can be trusted.

1. Turn off the RGA filament and disconnect it.

2. Record the pressure and then close the angle valve and gate valve on the RGA line to isolate it from the system.

3. Turn off the backing and turbo pump and let the turbo pump spin to a stop by slowly leaking the chamber. The slower the safer.

4.Slowly open the vents on the chamber and the turbo pump. Making sure not to raise the pressure too fast.

5. Once done venting the chamber, open the lid by removing the bolts and prying the lid open with a long flat head screw driver.

6. Removed previous parts and placed them into clean bags. Place new parts inside of the chamber and group them together close to the center.

7. Place the lid back onto the chamber and tighten the bolts in a circular pattern until tightened all the way with the wrench.

8. Make sure all vents are closed and turn the backing pump back on.

9. The turbo pump can be turned back on when the pressure reaches e-1 torr.

10. Wait until the chamber reaches a pressure of e-6 torr before opening the angle and gate valve on the RGA line. After the RGA line is open and the pressure is still below e-6 torr, the RGA filament can be turned on and a leak test of the lid should be performed.

11. After the leak test shows no leaks, proceed with starting the low temp bake.

I measured the temperature of the flanges where some of the electronics will go and I found that the RGA flange was at 55C and the two full range gauges were at 65C. I also stopped bake 9 to cool down for measurement.

Installed the heater elements into their fixture and prepped the cables by twisting the wires into pairs. We also installed the pins onto the wires and placed them into the peek DB 25 connector. The installation tool we had did not fit the pin size we had so the pins needed to be installed by hand by opening the connector and holding them in place. In the future we will need to make sure we twist the wires together, group them, and then splice them all to the same size for easier installation. We then grouped all the twisted pairs into a bundle and zipped them together. On the left with two peek zip ties is the power and on the right is the RTD with one peek zip tie. This orientation remains true when looking at the feed through flange from the outside with the power port on closest to the wall.

We also installed the heater elements numbered 1-8 starting from the left in image 3. These elements have numbers as resistance data was taken before as to identify the heaters after they are in the chamber. After installing the DB 25 connectors we tested that the pins were in the right orientation by using a volt meter and testing the resistance where the cable runs into the the actual power supply. It seems that all the pins were properly installed and the resistance values all match with each one gaining about 2 Ohms from the cable itself.

Then the pump down was started. The pump was very slow and we suspected a leak but after changing the o-ring pump down was not any faster and we decided to leave it over break as it seemed to just be water outgassing from the aluminum. The chamber is now able to be RGA scanned and leak tested before the next bake as it is low enough pressure.

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.