Metal-free and gasless space charge compensation of low energy ion beam by using surface-carbonized silicon field emitter array

Abstract

Surface-carbonized silicon field emitter array (Si:C-FEA), basically metal-free and gasless, was applied to a space charge compensation for neon ion beam after 700 mm, running with 0.5 keV and 15 μA. Estimated low energy electrons of 2.7 eV at maximum with current of 7.7 μA extracted from Si:C-FEA electron sources, which consisted of 7164-tip emitter cones and electron deceleration systems, were supplied into the ion beam. Transportation property was evaluated from the distribution of the current density of the ion beam with respect to its emittance. The distribution of the ion current density was narrowed and intensified by the electron supply. The transportation efficiency was improved from 56% to 87% by supplying electrons with the Si:C-FEA electron sources. This result showed the nearly complete space charge compensation similar to the reference result of the filament with transportation efficiency of 91%.