Lorentz Force Demonstrator

Description

PLEASE NOTE: Advanced Physics Equipment is built-upon-order. We do not stock these items in house, but order them built when an order is placed. Build orders take approximately 90 days.

Compact, All-In-One Apparatus for Investigating Electron Beam Behavior
Show Magnetic and Electrostatic Deflection, measure elm
Light-Shielding Enclosure Allows Use in Lighted Room

The Lorentz Force Demonstrator is a "fine beam tube" device in which a sharply focused electron beam is projected into a vacuum containing a trace of inert gas. Ionization of the gas around the electron beam creates a glowing discharge marking the path of the electrons and helping to maintain the sharp focus of the beam. The demonstrator shows deflection of the beam by transverse electric fields and by magnetic fields of various orientations. The value of elm can be found by bending the electron beam into a circular path with a homogeneous magnetic field and measuring the accelerating voltage of the electron gun, the strength of the magnetic field and the radius of the circular beam path.

The equipment consists of a vertically oriented vacuum tube and a pair of Helmholtz coils mounted on a base which contains all the necessary power supplies and measuring instruments to operate the tube and demonstrate the properties of an electron beam. The entire apparatus is mounted in a light shielding case with a mirror and scale for no-parallax measurements and a detachable front panel for storage. Binding posts on the rear panel allow external multimeters to be attached for more precise measurement.

The vacuum tube contains an electron gun assembly oriented to project the electron beam horizontally and carries a pair of electrodes for electrostatic deflection in the vertical direction. The tube socket is mounted on the top of the power supply unit, and it can be rotated 180 degrees about hte vertical axis to vary the orientation of the electron beam to the Helmholtz coils. A scale and pointer indicate the position of the tube.

The Helmholtz coils are also permanently mounted on the top of the power supply unit and carry and adjustable and removeable transparent scale for measuring the diameter of the electron beam's circular path. A mirror is mounted on the back of the case to eliminate parallax in determining the electron beam, position. Two red LED's mounted on the Helmholtz coil frame indicate the direction of th current through the coils.

The power supply provides the filament power, the grid and accelerating voltages, and the electrostatic deflection voltages to the electrode assembly, and also the current for the Helmholtz coils. The accelerating voltage and the Helmholtz coil current are indicated on built-in panel meters and are adjusted by two knobs on the front panel. The electrostatic deflection voltage is adjusted by a separate knob. Both the deflecting electrodes and the coils are provided with three position switches for controlling the polarity of the voltages and turning them off.

A full operator's manual with experiment description is included.

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