Abstract: An ion source 10 for producing a beam of ions from a plasma is disclosed. A plasma is created at the center of an anode 12 by collisions between energetic electrons and molecules of an ionizable gas. The electrons are sourced from a cathode filament 11 and are accelerated to the anode 12 by an applied electric potential. A projection of the anode and a magnetic field having an axis aligned with the axis of the anode act together to concentrate the flow of electrons to the center of the anode 12. The ionizable gas is introduced into an ionization region 13 of the ion source 10 at the point of concentrated electron flow. Ions created in the ionization region are expelled from the ion source as an ion beam centred on the axis of the magnetic field. The surfaces of the anode are coated with an electrically conductive non-oxidising layer of Titanium Nitride to prevent a build up of an insulating layer on the anode.

Abstract: An ion source (10) for producing a beam of ions from a plasma is disclosed. A plasma is created at the center of an annular anode (12) by collisions between energetic electrons and molecules of an ionisable gas. The electrons are sourced from a cathode filament (11) and are accelerated to the anode (12) by an applied electric potential. A magnetic field having an axis aligned with the axis of the anode acts to concentrate the flow of electrons to the center of the anode (12). The ionisable gas is introduced into the ion source (10) at the point of concentrated electron flow. Ions created in the resultant plasma are expelled from the ion source as an ion beam centered on the axis of the magnetic field. The surfaces of the anode are coated with an electrically conductive non-oxidising layer of Titanium Nitride to prevent a build up of an insulating layer on the anode.