Studies of a magnetically compressed electron beam

Magnetic compression augments the techniques of gun design in areas where voltage breakdown between adjacent electrodes prevents the shaping of the beam by electrostatic fields. The results of pinhole probing experiments of a perveance A/V^3/2beam are reported. Using the beam from a gun with an electrostatic area compression of 80:1 the beam was further compressed by suitable magnetic fields into a stable flow to an area compression of 250:1, 500:1 and 1000:1. The compressed beam has an axially invariant, almost Gaussian cross section which may be analyzed by the Pierce-Walker statistical theory of thermal velocities. Results of a comparison between theory and experiment are given.