Fine Beam Tube (Neon-Filled) with Connector Base

The Fine Beam Tube is used for investigating the deflection of cathode rays in uniform magnetic field produced by pair of 300 mm Helmholtz coils. In addition, it can also be used for quantitative determination of the specific charge of an electron e/m.
Located inside glass bulb with neon residual gas atmosphere is an electron gun, which consists of an indirectly heated oxide cathode, Wehnelt cylinder and perforated anode. The gas atoms are ionised along the path of the electrons and narrow, well-defined, luminescent beam is produced. Incorporated measurement marks facilitate parallax-free determination of the diameter of the circular path of the beam deflected in the magnetic field. The Fine Beam Tube is mounted on base with coloured connectors. In order to protect the tube, protective circuit is built into the base, which shuts off any voltage in excess of the base's pre-set cut-off voltage. The protective circuit prevents excessive voltages from damaging the heater filament and ensures "smooth" switch-on response once the voltage is applied. Requires 0-300 DC power supply and 300 mm Helmholtz coils.

• Filament voltage: to 12 DC
• Filament current: 300 to 450 mA
• Anode voltage: 200 to 300 V
• Anode current: 0.3 mA
• Diameter of fine beam path: 20 to 120 mm
• Division spacing: 20 mm
• Tube diameter: 160 mm
• Total height incl. base: 260 mm
• Base plate: 115 115 35 mm
• Weight: approx. 820 g