Magnetic compression of axially symmetric Brillouin-focused electron beams

A study has been made of high-current density Brillouin-focused electron beams formed with magnetic compression. Analysis of the problem was by numerical calculation of electron trajectories using a digital computer. Electrostatic field data were measured using a resistance network analog. The effect of the magnetic field was calculated as an equivalent potential. An experimental system based on the results of the analysis was designed and tested. A Müller-type electron gun was found to provide a more uniform current density than a corresponding Pierce type. Experimental results were in close agreement with design objectives. For an area magnetic compression of 10 to 1, a focused beam approaching ideal Brillouin flow was achieved.