PPM focusing of convergent beams emerging from partially shielded cathodes

Beam entrance conditions were investigated for PPM focusing of a convergent electron beam emerging from a cathode partially shielded from the magnetic field. The investigation was carried out with the aid of an analog computer and has resulted in a useful design procedure. A discussion of the theoretical aspects of the design procedure is presented along with verifying computer results. Experimental results which show close agreement with computer results are also presented.