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Entry  Wed Apr 21 00:08:15 2021, Koji, Update, PSL, PSL Table (sort of) covered / HEPA "chimney" 20210420235324_IMG_0560.jpeg20210420235304_IMG_0559.jpeg20210420235243_IMG_0558.jpeg20210420235344_IMG_0562.jpeg
    Reply  Wed Apr 21 01:14:03 2021, Koji, Update, PSL, PSL Table (sort of) covered / HEPA "chimney" P_20210421_005056.jpgP_20210421_005114.jpgP_20210421_005302.jpg
Message ID: 16056     Entry time: Wed Apr 21 00:08:15 2021     Reply to this: 16057
Author: Koji 
Type: Update 
Category: PSL 
Subject: PSL Table (sort of) covered / HEPA "chimney" 

Shutdown Procedure:
PSL Shutter closed / MC Autolocker disabled / PSL mechanical shutter closed / Laser injection current turned to zero / Laser turn off (red button) / Laser key turned off

The laser stat before the shutdown:
- LD Temp A: Set 22.07 (Untouched)
- LD Temp B: Set 21.03(Untouched)
- Laser Injection Current: Dial 9.53, Actual 2.100 -> Dial was moved to zero upon shutting down
- Laser Crystal Temp: Dial 3.34 (untouched)  Set 30.57 Actual 30.60 (Untouched)

PSL Table covering

- Because of the so many cables going up and down, sealing the PSL table with the metalized sheet was not easy. Therefore, the sheets have been just softly laid above the optics. (Attachment 1)
- The largest sheet which covers the east half of the table was taped to the table at the bottom, so that the air from the chimneys (see below) does not come up to the table

- The large dust could come from the opening of the enclosure during the filter replacement. So it was considered to be easier to seal the openings. (Attachment 2)
- Of course, the HEPAs are going to be tested after the maintenance work. It means that vent paths were needed so that the seals do not explode with the pressure (together with dust).
- Thus, the tubes of the sheets are attached to the seals to form "chimneys" for guiding the airflow beneath the table. (Attachment 2/3/4)
- This configuration was not meant to be sufficiently strong for a continuous run of the fans. Long running of the HEPAs may cause the failure of the seal tapes.
  Therefore the HEPA test should be done with a low flow rate and/or a short period of high flow.

- Once the work has been done, all the sheets should be carefully removed without scattering the fallouts onto the optics.


Attachment 1: 20210420235324_IMG_0560.jpeg  556 kB  Uploaded Wed Apr 21 01:09:01 2021  | Show | Hide all | Show all
Attachment 2: 20210420235304_IMG_0559.jpeg  653 kB  Uploaded Wed Apr 21 01:09:49 2021  | Hide | Hide all | Show all
Attachment 3: 20210420235243_IMG_0558.jpeg  579 kB  Uploaded Wed Apr 21 01:10:02 2021  | Show | Hide all | Show all
Attachment 4: 20210420235344_IMG_0562.jpeg  577 kB  Uploaded Wed Apr 21 01:10:02 2021  | Hide | Hide all | Show all
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