An ion source is disclosed including: a chamber disposed about a longitudinal axis and containing a gas, a magnetic confinement system configured to produce a magnetic field in a confinement region within the chamber, an electron cyclotron resonance driver which produces a time varying electric field which drives the cyclotron motion of electrons located within the confinement region, the driven electrons interacting with the gas to form a confined plasma. During operation, the magnetic confinement system confines the plasma in the confinement region such that a portion of atoms in the plasma experience multiple ionizing interactions with the driven electrons to form multiply ionized ions having a selected final ionization state.