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Message ID: 2552     Entry time: Fri Apr 9 09:37:26 2021
Author: Stephen 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Started cooldown with shielding, workpiece Si cantilever 

2021.04.08, StephenA

Karthik had completed in-chamber alignment efforts during a prior visit. In air alignment also completed following viewport move.

0) Removed lid for access to chamber.

--> posted demo video to ligo.wbridge QIL Cryostat HowTo Playlist.

1) Mounted RTDs to final positions - locations are Heater (cryo varnish+cigarette paper, pictured in IMG_8558 curing under weight of upsidedown bolt), Inner Shield (cryo varnish+cigarette paper, pictured in IMG_8559), Cold Finger (spring clamp), and Workpiece (spring clamp).

--> Final chamber layout may be viewed in IMG_8562

--> Note that Karthik's Si cantilever, mounted vertically in the right of the image, is NOT bolted down to the baseplate (just located on baseplate by dog clamps, held down via gravity). This will need to be investigated to enable workpiece cooling.

2) Installed radiation shield lids - no bolts to expedite the process and to see if there is any bulk motion during pumpdown and thermal cycling.

--> note that the lid for the outer radiation shield seems to interface with the current shield orientation perfectly; if there was a mismatch, it would point toward the inverted orientation being intended, but this seemed pretty definitive.

3) Installed the cryostat lid - final positioning and alignment made easier by teflon rails!

--> posted demo video to ligo.wbridge QIL Cryostat HowTo Playlist.

4) Pumped down - single button press to turn on pumping station.

--> note that it took about 1 hour for both gauges to reach a few mTorr.

5) Confirmed function of heater - set PID setpoint to 350 K and enabled outputs, observed temperature rise in heater RTD.

--> note that PID autotuning should be done at steady state with workpiece RTD, before enabling outputs again!

6) Turned on cryocooler - flip power lever and turn on green system switch.

--> start time was 10 am.

7) Started temperature datalogging to USB - press dull red indicator dot on upper right corner of CTC-100 once, and note that indicator is now bright red.

8) Remaining photos posted to the ligo.wbridge QIL Cryostat Photo Album

Attachment 1: IMG_8558.JPG  2.939 MB  Uploaded Fri Apr 16 11:35:26 2021  | Hide | Hide all
Attachment 2: IMG_8559.JPG  2.274 MB  Uploaded Fri Apr 16 11:40:10 2021  | Hide | Hide all
Attachment 3: IMG_8562.JPG  2.867 MB  Uploaded Fri Apr 16 11:51:36 2021  | Hide | Hide all
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