Daedelon E-Beam Unit
Electromagnetic Deflection of Free Electron Beam
Sargent Welch E-Beam Unit
Sargent Welch E-Beam Unit
Electromagnetic Deflection of Free Electron Beam
Electromagnetic Deflection of Free Electron Beam
diagram of apparatus

 

Code Number: 5H30.21

Demo Title: e/m - Electromagnetic Deflection of Free Electron Beam

Condition: Excellent

Principle: Measure e/m of Electrons

Area of Study: Electricity & Magnetism

Equipment: 

Daedelon E-Beam Unit, Sargent Welch Electron Beam Deflection Tube, 12 V DC Power Supply, 5 kV DC Power Supply (2), Helmholtz Coils (2), Keithley Multimeters (2), Large Tube and Coils (2nd Floor), Heathkit Power Supply (2nd Floor), Variac, 6 Volt Transformer, and Amp and Milliamp Meters (2nd Floor).

Procedure:

The Daedelon unit is designed with safeties so that unit is not damaged.  It will go through a 30 second countdown when first switched on to warm up the filament.  Nothing can be done until this countdown is over.  Data on the unit is:  Coil radius = 150mm.  Coil separation = 150mm.  Coil turns = 130.

Assemble the large Sargent Welch apparatus as shown and according to the diagrams enclosed.  The multimeters shown are used if you are going to try to make a measurement and calculation in the classroom.  Trying this before class for practice is a very good idea.  The large setup shown is the one that was used in the labs upstairs.  This is a good one to use in certain cases as you can get the beam to bend full circle.  Be sure to keep the current under 4 amps so as not to burn up the filament.

NOTE: The switch on the Heathkit power supply should be toward the right or B+ output side.  The B+ output knob should be turned up about 1/2 way.  Turn up the variac slowly.  You will not see any movement of the milliamp meter until you reach 3.5 to 4 amps at which time it will move rapidly with small changes of the variac.  A 4.5 amp fuse in the filament circuit would be a good idea when this is used in the classroom.

With the large tube and coils system the Heathkit power supply and some of the meters may be replaced with the current control power supply found in room 250.  The procedure to setting the supply to work with this system is to short the power supply (+ and - terminals) and then apply a little voltage.  Turn the amps up to 4.5 and turn off.  Unplug everything and the power supply should be set to self limit at 4.5 amps.

The electron tube for the large apparatus can still be had from Sargent-Welch.  Item # WL0623.  They usually have them in stock but run a new batch about every year.

References:

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5H30.21 - e / m - Free Electron Beam
5H30.21 - e/m - Spiraling Electron Beam