3B Scientific Teltron Critical Potentials Tube S with He-Filling - Manual (Page 4)

4
numerical values for t
1
and t
2
in s
determined as above.
• Set up a graph with the quantity E on the x-
axis and the quantity I on the y-axis. (See
Fig. 3).
• In order to display the ionisation curve,
reverse the polarity of the collector voltage.
HERTZ TUBE CONSOLE
60
V
A
+
1
RING
2
SLOW
RUN
MIN
MAX
V
A SET
3
4
1 SLOW 2 1 2 FAST
0...±1 VOLT OUT 0...±1 VOLT OUT
OUT 3
4
200 mV !
+ I
in
A
U out
A
U in
A
+
U out
B
U in
B
+
Channel
Rate
Store Date/Time
On/Off
Fig. 2 Connection of 3B NETlog TM to the control unit for critical potential tubes
Fig. 3: Determination of critical potentials for helium atoms (curve recorded using 3B NETlog TM )
7.2.2 Procedure with an oscilloscope
• Connect output Fast1 on the control unit to
Channel 1 (X deflection) on the oscilloscope
and output Fast 2 to Channel 2 (Y deflec-
tion). (See Fig. 4)
• Set the minimum voltage output V
A
on the
control unit to approximately 10 V and the
maximum voltage to about 35 V. Use a mul-
timeter to measure the voltage between
socket 3 and ground or socket 4 and
ground, which will be a factor of 1000 times
smaller.
• On the DC power supply, set the heater
voltage to 3.5 V.
Oscilloscope settings:
Channel 1: 50 mV/div
Channel 2: 0.2 V/div
Time-base: 5 ms
Trigger on Channel 1
• Vary the heating voltage, the upper and lower
limits of the accelerating voltage and the os-
cilloscope parameters until the best curve can
be seen.
• In order to display the ionisation curve, re-
verse the polarity of the collector voltage.
• Zur Aufzeichnung der Ionisationskurve die
Polarität der Kollektorspannung vertau-
schen.