40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  PSL  Not logged in ELOG logo
Entry  Sat Mar 9 11:38:10 2013, Evan, DailyProgress, Vacuum, Cavities inserted; chamber pumping down 
    Reply  Tue Mar 12 18:20:21 2013, tara, DailyProgress, Vacuum, Cavities inserted; chamber pumping down IMG_0815.JPG
       Reply  Wed Mar 13 10:50:31 2013, Koji, DailyProgress, Vacuum, Cavities inserted; chamber pumping down 
          Reply  Wed Mar 13 23:52:12 2013, tara, DailyProgress, Vacuum, Cavities inserted; chamber pumping down 
             Reply  Thu Mar 14 17:27:42 2013, Koji, DailyProgress, Vacuum, Cavities inserted; chamber pumping down 
Message ID: 1114     Entry time: Tue Mar 12 18:20:21 2013     In reply to: 1112     Reply to this: 1116
Author: tara 
Type: DailyProgress 
Category: Vacuum 
Subject: Cavities inserted; chamber pumping down 

After pumping the chamber down for two days, I disabled the turbo pump and turned on the ion pump. The initial current was 7mA. After a day now it is 0.38 mA. It was better before, see PSL842, (started the ionpump at 1mA, and operated at less than 0.1 uA). If this is true, this means the pressure will be about a factor of 0.38mA/0.1uA ~ 3800 higher than before. (the calculation is based on this equation, where the current is directly proportional to the pressure.

 

The flanges do not flatly touch each other. There's a tiny bit of something in the middle that causes a gap as shown below. This might be the reason why the ion pump current is high, or it might be some out-gasing problems of the in-vac materials. I think we can try to spray isopropanol around the flange to see if the current comes up, but I think it is a bad idea for the ion pump. I'll ask Steve or Koji for their opinions.

 IMG_0815.JPG

The pictures during the installation can be found onpicasapage

Quote:

 [Tara, Koji, Evan]

Tara and Koji spent the better part of yesterday afternoon inserting the new cavity assembly into the vacuum chamber. In the process of putting the window back on the chamber, the old copper gasket may or may not have hit the inner surface of the window, so Koji performed a drag wipe. Tara and Koji then inspected the window under a high-power bulb, and I think the consensus is that there's no visible damage.

The chamber is currently pumping down. Unfortunately, there appears to be a small speck of something trapped between the window and chamber flanges, so there's a small gap on one side of the joint. We'll see if we can achieve high vacuum.

 

ELOG V3.1.3-