Ask JC Anything

Here we list the questions to JC.

  1. What are the N2 cylinders used for? Why do they trigger the Vacuum Interlocks?
  2. Why are you so good at your job?

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Ask Steve Anything

Here we list the questions to Steve. (remember that we want a video of the Q&A, Hunter Thompson style)

  1. What limits the pressure in our system after a week of turbo?
  2. Why do we need to use N2 for the vacuum valves? Isn't compressed air not enough?

    • A: (transcribed by Gautam, as described to Jon and me): Steve's concern was that air compressors would have non-negligible transmission of oil-content to the compressed air, which in turn could dirty the VEA (although he thinks the inside of the vacuum envelope itself would be sufficiently well isolated). He thinks that a compressor based solution will be viable iff we can find a dry air compressor unit. A related question was "Why do we have to replace the nitrogen cylinders ~every 3 days?". Steve thinks that this rate of leaking from the valve is consistent with how it is spec'ed to work (although I myself have not seen a datasheet/spec).

    • Rana still thinks we should look into getting one of these. We can find a few options and get Steve to sign off on one of them.
  3. Do we need these huge isolation transformers next to Steve's desk and under the HP printer?
  4. Why can't we get good Sugar Napoleons at the Red Door cafe anymore?
  5. What is the safe way to clean the cryo pump if we want to use it again?
  6. VC2 may have been accidentally cycled during the vacuum upgrade. What (if any) are the implications?
  7. What are safe conditions to turn the RGA on?

    • A: 2e-5 torr should be okay to run an RGA scan. Steve recommends a thorough bakeout of the RGA, by redoing the heating tape assembly as well.

  8. How high can we allow the temperatures of TP1, TP2 and TP3 to go during pumpdown? In the elog, I've seen numbers as high as 38 C, but for the July 2018 pumpdown it peaked at 32 C, but the Varian manual says 60 C is when the in-built shut-off cuts in. Presumably if there is risk of damage to the pump it will automatically shut off (which is possibly bad for TP1?). What is the quantitative way to decide?

    • A: Since we have the digital readbacks, Steve reckons its okay to go up to 40C, but he recommends being conservative compared to the specs in the manual. Regarding the pumping speed, the lower RPM mode (a.k.a. Standby) is preferred because it can handle a sudden jump in the pressure better than at the higher RPM setting. Steve said that the two types of turbo-pumps we have (small capacity and the OSAKA) have different modes of operation.

  9. What do we do about the low oil level in RP1 and RP3? We found the machining oil, but should we refill it? To what level? How do we minimize risk of pumping some of the hydrocarbons into the main volume after the refill?
  10. Rana: Where are the spare green optics (removed from X end) now?
  11. Why are there so many ants in the lab?
  12. Rana: What kind of driver do we need for the Big Ling? (the red one)

Ask_Steve_Anything (last edited 2022-10-25 18:20:47 by FranciscocarcobaATligoDOTorg)