3B Scientific Teltron Luminescence Tube D User Manual
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3
sufficient infra-red emission from the cooling
filament to partially quench phosphorescence.
•
Set the voltage to about 4500 V and note
the current flowing (typically 0.02 µA due to
leakage on or through the glass bulb).
•
Illuminate the phosphors with ultra-violet
light and note that there is no change in cur-
rent.
Since there is no change in current, it is clear
that the emission from the phosphorous materi-
als is due to excitation processes and not to
ionisation.
5.3 Phosphorescence and quenching
•
Remove all connecting leads from the tube
(refer to fig. 3).
•
Set up a ultra-violet light source so that the
gun side of the screen can be illuminated.
•
Set up a infra-red light source so that the
backside of the screen can be illuminated.
•
Illuminate the phosphors with ultra-violet
light until the green phosphor has built up to
full intensity.
•
Switch off the ultra-violet light source and
immediately switch on the infra-red light
source.
The phosphorescence of the unprotected half of
the green phosphor is quenched while the other
half remains unaffected.
DC POWER SUPPLY 0 ... 5 kV
0
1
2
3
4
5
KV
0 ... 5 kV
U
F
U
A
-
Fig. 1 Excitation by cathode ray bombardment