3B SCIENTIFIC U192001, Инструкция

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8
•
Check the locking pin of the cover for any dam-
age.
•
Check that the leaded glass dome and brass
collimator are free of damage and firmly se-
cured.
•
Check that the mains indicator lamp is function-
ing correctly by closing the cover, connecting the
equipment to the mains, setting the timer and
turning on the key switch. The indicator lamp
should then light. The high voltage indicator
should not be lit.
•
Check that the timer is working properly by turn-
ing on the key switch and setting a time.
•
Check the timer relay by setting the timer to 0.
The mains indicator should not be lit even if the
equipment is plugged in.
•
Check the high voltage indicator lamp. Set a time
on the timer with the cover closed and locked
(locking pin in centre position) and turn on the
key switch. The high-voltage indicator lamp
should not light up at this stage. Switch on the
high voltage using the ON/OFF button. The indi-
cator lamp and the light-ring of the button
should then light up.
•
Check the switching function of the safety device
in the cover hinge as follows: with the high volt-
age switched on, slide the cover sideways with-
out opening it, so that the locking knob remains
within one end of the dumbbell-shaped slot. The
high voltage should switch off automatically, so
that the high-voltage indicator lamp and the
light-ring also go off.
8.2 Putting the X-ray apparatus into operation
8.2.1 Opening, closing and locking the cover
•
To open the cover towards the side where the
measuring arm is located, push it sideways and
lift it open.
•
To close the cover, insert the locking pin into the
dumbbell slot on the side where the measuring
arm is located.
•
Push the cover sideways so that the locking pin
audibly snaps into the centre position.
The cover is now secured against any unintentional
opening. The high voltage supply may now be
switched on.
8.2.2 Turning on the X-ray apparatus
•
Select a time on the timer.
•
Turn on the X-ray apparatus using the key
switch.
The mains indicator lamp should now light up. Once
the time is up, the machine should switch itself off.
8.2.3 Closing the cover and switching on the high
voltage
•
Once the mains is connected, select the high
voltage supply U = 20 kV/30 kV via the slide
switch.
•
Close the cover and lock it with the locking pin
in the centre position.
•
Press the high voltage button.
The high-voltage indicator lamp and the light-ring of
the ON/OFF button light up, and X-radiation is gen-
erated.
•
Check for the presence of an X-ray beam using
the fluorescent screen, ionisation chamber or
Geiger-Müller tube.
8.2.4 Setting and measuring emitter current
•
Connect a voltmeter with a measurement range
of 10 V DC to the jack socket using an adapter
cable.
•
Use a screwdriver to set the desired emitter cur-
rent on the trim potentiometer.
The following relationship applies:
I
A
[A] = U
A
[V] / 10
5
[Ohm]
Thus, for example, a DC voltage of 8 V indicated on
the voltmeter corresponds to a tube current of 80
µA.
1
8.2.5 Switching off the high voltage and opening the
cover
•
Press the high-voltage ON/OFF button, allow the
delay time needed for the unlocking of the cover
safety catch, and slide the cover sideways.
8.2.6 Sample holder
Monocrystals (NaCl, LiF, etc.) can be attached to the
sample holder (see Fig. 5). The clamp and base can
be removed by undoing the relevant screw.
•
Fix the monocrystal into the sample holder with
the clamp thus defining the angular alignment
of the crystal. The rough side of the crystal
should point towards the X-ray tube.
•
Read off the angle
θ
between the sample holder
and the beam axis.
8.2.7 Measuring arm
The measuring arm has 18 slots for experiment ac-
cessories and detectors. An angle between measuring
arm and X-ray beam of 2
θ
can be read on the arm's
protractor scale. For accurate measurement of angle
there is also a vernier scale. It is used as follows:
•
Set the arm to the next whole marking for 2
θ
.
•
Set the fine adjustment trimmer against the
thread tension to 0 while holding the measuring
arm.
The arm can be set by an extra
±
4° using the fine
adjustment trimmer.