Log entry time 09:38:55 on April 14, 2012

Entry number 374348

This entry is a followup to: 374340

Followups:

• 374353 04/14/12 09:56 duve [target]

If the microwaves and the beam are steady, as it looks like it may be, 
you can also get polarization jumps from changes in the flow from the run 
valve.

We've had a bit of trouble with the nose level probe sticking now and 
again. If the run valve is opened a bit too much by the PID controlling 
it, the level rises in the nose, while the level probe could be stuck 
around 50%.  When the level probe catches up, it will read 80% all of a 
sudden, for example.  The PID loop will then close down the run valve to 
get the level back to 50%.

When we are down at very low temperatures, flow from the run valve acts 
to raise the pressure and thus the temperature in the nose.  With the run 
valve closed, the temperature drops and the polarization increases.  Once 
it opens, the polarization will drop back down.

I wouldn't worry about polarization jumps on the order of a couple 
percent.  If the TO can correlate the polarization jumps with the run 
valve or main flow, then we really aren't worried.