Hi all,
today I have no mysterious problem but a funny observation, which looked
like a mysterious problem.
What happened?
Locking and shimming was fine. If I opened the spectrometer room
door very fast, the lock decreased by about 30%. If I closed
the door very fast, the lock level reached the previous value.
O.K. a pressure dependency, which might happen, if the
helium pressure is coupled to the air pressure in the room
using a simple exhaustive valve.
But that was not true. That spectrometer works with a constant
helium pressure.
Let's continue.
If I opened the spectrometer room door very soft nothing
happened.
And now the combinations ....
Open the door very fast and close it softly.
- Lock decreases but doesn't come back to the previous
level
Repeat this procedure.
- Lock continues to decrease but still doesn't come
back
Open the door very careful and close it suddenly
- Lock level improves
Repeat this procedure
- Lock level improves once again
Unfortunately this procedure was not suited to improve the lock
to an unlimited level. ;-)
What happened?
The temperatur gas flow was as high to allow the sample to
come down. If I lowered the room pressure suddenly by
opening the door very fast, the sample moved upwards
parts of a millimeter. Due to adhesion (no spinning)
the spinner remained in that position. The exception was a sudden
increase of the air pressure, which forced the spinner to move
down.
Of course this was easy to correct using a different gas flow.
But the story continues a little bit.
The helium pressure is constant but the same isn't true for
the nitrogen pressure. I increased it a little bit simply by blowing
into the nitrogen tank. Unfortunately the lock changed during
this operation. I never made this attempt before.
That observation means, that in spite of the constant helium pressure
the magnet is sensitive against the external air pressure changes. -(
Have a nice day.
Rainer
Received on Tue Apr 11 2006 - 16:58:34 MST