Comparison of measured emittance of an H- ion beam with a simple theory

Ion beam phase space is frequently modeled with a simple theory having a few parameters; for example, the Kapchinskii-Vladimirskii (K-V) equations. For a real beam the normalized phase-space density par. delta2i/par. delta x par. delta in one transverse plane x, averaged over the other plane y, is usually far from that of a K-V distribution. We develop a simple theory based on plasma ion temperature that under some conditions gives a good description of the measured emittance of our H- ion beam at about 15 keV