An exemplary ion source for creating a stream of ions has a chamber body that at least partially bounds an ionization region of the arc chamber. The arc chamber body is used with a hot filament arc chamber housing that either directly or indirectly heats a cathode to sufficient temperature to cause electrons to stream through the ionization region of the arc chamber. A seals has a ceramic body having an outer wall that abuts the arc chamber body along a circumferential outer lip. The seal also has one or more radially inner channels bounded by one or more inner walls spaced inwardly from the outer wall.