A heavy ion pre-injector for the ICT-ion implanter

A cheap and versatile hollow cathode electron bombardment ion source system including its ion extraction-cum-focussing assembly for obtaining intense heavy ion beams of solids and gases is described. The extractor region is designed to include more than 15deg total beam angle of extracted beam for producing focused ion current densities upto 60mA/cm2 to serve as a pre-injector for the ICT(insulated core transformer) type ion implanter. The extraction-cum-focussing lens is a low aberration strong Einzel lens system of all araldite and metal construction with optical elements of proper quality and location to suit low voltage injection and subsequent ion analysis. The injection can be selected anywhere between 2 to 10 keV for singly charged ions with typical extraction currents of 500/μ, using a ring anode and a source aperture of 20 mil. Einzel lens focussing assembly allows continuous adjustment of the beam convergence to about 5deg and the beam size to approximately 5mm in diameter with about 10 KV central electrode potential. Test results of source characteristics for both the accelerating and decelerating model of beam formation have been made. (author)