Hello again,
many thanks for all of the helpful input. Unfortunately it wasn't helpful for
the magnet. The magnet quenched during last weekend.
Nevertheless I believe, I should summarize all of the valueable responses.
==========
Slowly increasing field
==========
Mostly I got the hint this might be due to Z2 or Z0 cryoshims. I had a look
into the magnet manual. There are X, Y and Z cryoshims only.
Ulrike had the idea of a broken REF unit. Indeed the REF unit is the heart of the console.
Every single Hertz of frequency shift, every single degree of phase shift is generated
from one single base frequency of 10 MHz using only digital procedures.
If this value of 10 MHz moves to lower values, this means the field apparen tly increases.
We checked the REF unit using the 10 MHz output of a second spectrometer. This resulted
in a proton shift of about 70 Hz, which means, the 10 MHz reference frequency between both
spectrometers differs by approximately 3 Hz. That's an excellent value, I believe.
Finally I have no idea about the true reason of the temporarily increasing field strength.
==========
expinstall and missing topspin1d2h data set
==========
That's rather easy. expinstall takes the data sets in ...../par.Avance modifies them
and puts the modified data sets into the ...../par directory. One input for expinstall
is the spectrometer routing. If there is no deuterium routing defined, the corresponding data
sets are not taken into account.
==========
user defined data sets
==========
They are not touched at all by expinstall.
==========
Inactivity after failure of the helium sensor
==========
Yes, of course you are totally right, it's a strong alert signal getting wrong values from the
helium sensor. I am retired and wasn't aware of this issue. People called me, if it even was
impossible to insert the helium transfer line.
To remove the ice here was a little bit time consuming, but finally no real challenge. To get the
dip stick into the magnet, I used a long copper rod with about 3 mm diameter to remove the ice.
Finally I assume, that this copper rod made a channel into the ice, with exactly the diameter of
the dip stick. Maybe this channel together with the dip stick formed a longer "virtual dip stick",
which gave wrong results manually measuring the helium level. But that's only an assumption.
Once again many thanks. Even as an old man, there is always something to learn.
Greetings from Munich
Rainer
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Received on Sun Apr 21 2024 - 09:32:29 MST