3B Scientific Teltron Maltese Cross Tube D - Manual

3B SCIENTIFIC® PHYSICS
1
Maltese Cross Tube D 1000649
Instruction sheet
09/13 ALF
2 3 5 6
-
7
4 1
1 4-mm sockets for filament and
cathode
2 Heater filament
3 4-mm plug for connecting anode
4 Boss
5 Maltese cross
6 Fluorescent screen
7 Boss with 4-mm plug connected to
the Maltese cross
1. Safety instructions
Hot cathode tubes are thin-walled, highly
evacuated glass tubes. Treat them carefully as
there is a risk of implosion.
• Do not subject the tube to mechanical stresses.
• Do not subject the connection leads to any
tension.
• The tube may only be used with tube holder D
(1008507).
If voltage or current is too high or the cathode is
at the wrong temperature, it can lead to the tube
becoming destroyed.
• Do not exceed the stated operating parameters.
• Only change circuits with power supply
equipment switched off.
• Only exchange tubes with power supply
equipment switched off.
When the tube is in operation, the stock of the
tube may get hot.
• If necessary, allow the tube to cool before
dismantling.
The compliance with the EC directive on elec-
tromagnetic compatibility is only guaranteed
when using the recommended power supplies.
2. Description
The Maltese cross tube is used to demonstrate
how cathode rays propagate in straight lines in
the absence of any electric or magnetic field.
This is shown by placing a Maltese cross in the
path of the beam to throw a shadow on a fluo-
rescent screen. The tube is also used to show
how beams can be focussed by magnetic fields.
This serves as an introduction to electron optics.
The Maltese cross tube is a highly evacuated
tube with an electron gun consisting of a pure
tungsten, 'hairpin' heater filament and a cylindri-
cal anode all contained in a clear glass bulb.
The electron gun emits a diverging beam which
is detected by a luminescent screen. An alumin-
ium Maltese cross is suspended in the centre of
the bulb. The lower limb of the cross has a small
hole 3-mm in diameter so that the orientation of
the shadow can be distinguished when it is af-
fected by a magnetic field.