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.

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.

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.

[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.

[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.

I delivered new NEMA 5-15 (120V / 15 A) power cables to the lab for the following items:

• WS2 (cleanroom) cart - 10ft cable
• Electronics workbench overhead LED - 10ft cable
• Both PI heater controller sets - (2) 6ft cables

I installed the new cables on the WS2 cart and the workbench myself, and left the two 6ft cables (as pictured below) for Aiden to install on the PID controllers after the current bake is finished.

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.

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.

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.

Changed the pre filter inside of the 3 stage HEPA system next to the soldering station. It was rather dirty and I have attached images with a clean filter on the left and the used one on the right. I reset the pre filter age on the system. I tried to see if I could tell if the HEPA filter was dirty but I could not see it. I did not reset the age of the HEPA or UV stations. They are currently 378 days old.

Dr. Richardson and I took off the insulation on the lid again to add more insulation in-between the heater tape folds in addition to what was added on top of the tape after discovering discoloration. Also cleaned the lid with IPA wipes.

Also took more RGA data, one with the leak closed and one with the leak open. The graphs below this show that the SNR is improving with the ratio now looking to be around 3. The chamber is still too dirty to be commissioned and we will need to be baked again soon.

Plugged the temperature sensor back in after getting another extension cord. Removed the electronics box for the RGA as well as the full range gauge above the RGA line.

1. I was able to plot the final result with the data to the heater. I attached below the "3Combined_HighTemp_Gaussian_Plot." in this plot we can see better behavior on the Gaussian compared to the plot in ELOG 169, I was using the same data but with a different approach. On the ELOG 169, we have the center point isolated data and this new plot is the temperature more than 70 C isolated because we have a very good heater temperature distinguish do background. For the all data I got I was using a power current of 0.20A. To get the data I waited for 30 minutes until the heater became stable and after that, I started to take snaps, I took more than one snap for each one different 6 positions on the screen, and We can see the positions on ELOG 167.
2. Also I attached the calibration plot ("calibration_plot") between the measurements with the FLIR camera and thermocouple and we can see looks good if we compare the final plot.
3. For better analyses I attached a plot of the calibration line on the Gaussian plot.
4. To do: I will finish the final report.

Took some more data to look at the HC count. Initial data was from leaving the Argon leak closed and then left it open for 15 minutes and then took data for the open scenario. Attached are the graphs for these where attachment 1 is the closed scenario and attachment 2 is the open scenario.

From these graphs it looks like the signal-noise ratio of our calibration line is poor with the ratio between these two being 1.3. This means that the calibrated leak is barely being detected over the background. This should improve with more baking and pumping. I have also now attached overlayed graphs comparing the chamber when the leak is closed versus when it is open. As well as one comparing the chamber right after the bake versus the most recent data both with the leak open.

cleaning cleanroom and particle count

• 11:08 am: started particle count
  • zone 3:
    • 0.3 u: 4198
    • 0.5 u: 1080
    • 1.0 u: 581
• zone 4:
  • 0.3 u: 1247
  • 0.5 u: 623
  • 1.0 u: 415
• 11:24 am: break for removal of vac chamber insulation (pictures attached), with counts before removal as seen above, and counts after removal/replacement for zone 3 as follows:
  • zone 3:
    • 0.3 u: 2993
    • 0.5 u: 415
    • 1.0 u: 207
• 12:02 pm: began surface check and wipedown
• 12:13 pm: started vacuuming the floor
• 12:25 pm: finished vacuuming the floor
• 12:26 pm: started mopping the floor
• 12:32 pm: finished mopping the floor
• 12:32 pm: started cleaning the buckets
• 12:37 pm: started mopping with IPA wipes
• 12:43 pm: finished mopping with IPA wipes
• 12:45 pm: changed sticky floor mats
• 12:47 pm: started particle count
  • zone 3:
    • 0.3 u: 2951
    • 0.5 u: 290
    • 1.0 u: 41
• zone 4:
  • 0.3 u: 290
  • 0.5 u: 0
  • 1.0 u: 0