Maltese Cross Tube D

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Experiment Topics:_..

The following topics can be discussed with this highly evacuated tube:
• Linear propagation of cathode rays / of electron beams
• Electrostatic charging effects
• Electron deflection by a magnetic field
• Introduction to electron optics

Product Information:_..

The Maltese cross tube is a highly evacuated tube with an electron gun consisting of a pure tungsten, 'hairpin' heater filament and a cylindrical anode all contained in a clear glass bulb. The electron gun emits a diverging beam which is detected by a fluorescent screen. An aluminium 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 affected by a magnetic field.
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 fluorescent screen. The tube is also used to show how beams can be focussed by magnetic fields. This serves as an introduction to electron optics.

Specifications:_..

Filament voltage U_F:	max. 6,3 V AC/DC
Anode voltage U_A:	2000 V – 5000 V
Anode current I_A:	typ. 180 µA at U_A = 4000 V
Voltage at cross:	2000 V – 5000 V
Current at cross:	typ. 75 μA at U_A = 4500 V
Glass bulb:	130 mm Ø, approx
Fluorescent screen:	85 mm Ø
Total length:	260 mm approx