Elekta Neuromag NM21283A, Руководство пользователя

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3 Basic tuning operations
14 NM21283A-A
hearing resistors, so that this can be easily achieved by feeding a suitable
current pulse into the resistor. Note that each sensor unit contains three
SQUIDs, so three channels are always heated together.
To heat a single sensor that contains a particular channel:
1. Select the view channel by entering the channel name to the selection
box of the working point controls at the left side of the display area.
Press return and check that the name of the channel appear on the top
of the display.
2. Select
Command
>
Heat sensor
from the menus.
To heat all the sensors:
1. Select Command > Heat all sensors from the menus.
If you are making a noise measurement, you need also reset the electron-
ics after heating. See “Resetting channels” on page 13.
3.5 About saving and loading settings
Tuning settings can be saved on disk and loaded back to magnetometer
later on. Recommended practice is that there should be two or three stan-
dard settings files that contain carefully made good values for normal
usage and some special situations like using the device just after helium
filling or when the helium level is very low. In normal conditions one
good setting file should be enough.
If the automatic fine tuning of the system does not succeed, one should try
first to heat bad channels and if that is not enough, load a well known tun-
ing setting file. If this tuning still fails, contact your system administrator
to find out what has changed.
It is not recommended that the tuning settings are saved after each fine
tuning and then reloaded when tuning is needed next time, since then the
tuning settings files tend to “drift” and nobody really knows how the sys-
tem should perform when some particular file is used. It is usually better
to have fixed files that are saved only by the administrative personnel so
that the expected performance is known and possible changes in the sys-
tem can be detected.
To load tuning settings into tuner and magnetometer:
1. Select
File > Load tunings
from the menu. A dialog will pop up.
2. If the file suggested by the dialog is the one you want to load, press OK
to load the file. Otherwise press Load other to pop up an ordinary file
selection box and use it to select the file you want to load. See “Using
file selection boxes” on page 6.