A high−voltage telefocus electron gun with remote focusing

Abstract
A new design for a telefocus electron gun is presented. Features include a nearly constant minimum FWHM of 180 μ with beam currents of 1−400 μA at focal distances from 1/2 to 1 1/2 m. The gun is especially designed to operate under adverse vacuum conditions with background pressures as high as 10−4 Torr with accelerating potentials of 10 to 60 keV. In addition tn can be remotely focused and positioned from outside the vacuum chamber in which the gun is used.
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