Electron multiplier with switchable beam confinement structure

Abstract

An electron multiplier includes a plurality of staggered parallel dynodes. The dynodes include spaced confinement bumps along their lengths with active multiplying areas between the bumps. The confinement bumps and active areas therebetween define a plurality of channels which extend from a cathode at one end of the multiplier to the output end. Each channel traverses the staggered parallel dynodes and causes an electron beam to pass therethrough without substantial spreading. The electron multiplier includes additional structure for creating a high gain condition in the channels which are desired to be in an 'on' condition while simultaneously creating a low gain condition in the adjacent channels. Electrical potentials can be simply switched at the dynodes so as to change this first condition into a second condition where the relative gain parameters of the channels are reversed.