3B Scientific Electron Deflection Tube D - Manual

3B SCIENTIFIC® PHYSICS
1
Electron-Beam Deflection Tube D 1000651
Instruction sheet
11/12 ALF
5
7
2 1
-
4
6
2
1
1
2
10 9 8 7 6 5 4 3 2
3
1 Fluorescent screen
2 Lower deflection plate
3 Boss with 4-mm plug for
connecting deflection plates
4 Electron gun
5 4-mm sockets for connecting
heater supply and cathode
6 4-mm plug for connecting
anode
7 Upper deflection plate
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 circuit 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 electron-beam deflection tube is intended
for investigating the deflection of electron beams
in electrical and magnetic fields. It can be used
to estimate the specific charge of an electron
e
/m and to determine the electron velocity v.
The electron-beam deflection tube comprises an
electron gun which emits a narrow, focussed
ribbon of cathode rays within an evacuated,
clear glass bulb. A tungsten 'hairpin' filament hot
cathode is heated directly and the anode takes
the form of a cylinder. The deflection of rays can
be achieved electrostatically by means of a built-
in plate capacitor formed by the pair of deflec-
tion plates or magnetically with the help of the
Helmholtz coils D (1000644) magnetically. The
cathode rays are intercepted by a flat mica
sheet, one side of which is coated with a fluo-
rescent screen and the other side of which is
printed with a centimetre graticule so that the
path of the electrons can be easily traced. The
mica sheet is held at 15° to the axis of the tube
by the two deflecting plates.