Highly charged ion densities and ion confinement properties in an electron-cyclotron-resonance ion source

Absolute ion densities in an electron-cyclotron-resonance ion source (ECRIS) plasma have been measured using high-resolution x-ray spectroscopy of $(n=2)\ensuremath{\rightarrow}(n=1)$ emission lines from highly charged argon ions. Ion densities have been correlated to extracted currents. The evolution of the ion confinement times with charge state has been investigated for various plasma parameters: a linear increase of the confinement time with charge was found. This result leads to a better understanding of the ion confinement mechanism in ECRIS plasmas.