Experimental Investigation of Emittance Growth in Particle Beams Using Directly Heated Lanthanum Hexaboride Cathodes

摘要

This report presents the theory of nonlinear field energy as applied to emittance growth in a space charge dominated particle beam. An experiment to validate this theory is described and the experimental apparatus and results are presented. The experimental apparatus is designed around a directly heated lanthanum hexaboride (Lab6) cathode which yields a variable radial intensity electron distribution. We report the first use of such an electron gun, and its initial operating characteristics, which compare favorably with predicted theory. Keywords: Emittance growth, Particle beams; Lanthanum hexaboride; Cathodes; Nonuniform radial intensity distribution; Electron gun. (sdw)