| [Jon, Cao]
Summary : We resolved problems with heaters tripping power and were able to proceed with chamber baking
1. Circuit connection adjustment
After yesterday elog 137, today we resolved most of these issues. After Jon contacted Facilities, the LP3B 6 circuit was reset and the cleanroom filter & light panels resumed to work as normal.
Regarding the connection of the heaters. we made the following adjustments:
- High-temperature controller powering lid + upper volume heater: connect to LP3B 8 circuit (clean room sides, 2 outlets)
- High-temperature controller powering bottom + lower volume heater : connect to LP3B 4 circuit (workstation side, 2 outlets)
2. Replacement of vacuum nipple insulation
We had also received new insulation pieces from Worbo today to replace the existing insulation with the new ones (see images). These cover the 2 4" tubes (for 6" flanges ) and the 4 1.5" tubes (for 2.75" flanges). The new insulations fit perfectly on these tubes.
I also placed all insulation taken off from the last elog back onto the chamber ( these are insulations for the pumps and RGA lines).
3. Baking
We started ramping up chamber temperature at 1:41 pm over the course of two hours:
- Starting set point: 40 deg C
- Step increase: 10 deg C up to 80 deg C, 5 deg C from 80 deg to 120 deg C
- At each step, the temperature readouts show approx. 2.1 deg C overshooting, wait to settle back to approx 1.5 deg C overshoot before increase the set point again
We noticed some smoke emanating from flexible bypass line insulation but none from other locations that were previously smoking . We think this is because the high winding density around the bypass line for such a small volume. Adjustment for next bake: Change the location of PID controller RTD to the bypass line . For now, we remove the insulation around bypass to prevent insulation overheating and encourage convection cooling (see image)
The temperature of the chamber reached as stable 120 deg C without any power issues at 3:45 pm. I waited another 15 minutes to verify its stability and the official baking duration started at 4:00 pm Jun 29 2023. Since we are baking at 120 deg C instead of the standard 150 deg C for Aluminium, the duration for the bake will be over three days until Monday morning, upon which we will slowly ramp down the the temperature.
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