Time evolution of charge states in an electron cyclotron resonance ion source (abstract)a)

The production of high charge‐state ions in an electron cyclotron resonance ion source has been studied as a function of time using a pulsed Nd:YAG laser to ablate heavy metal (bismuth) ions into the plasma. The time required to produce a charge state has been measured by observing the arrival time of the ions at a Faraday cup after the source analyzing magnet. The results of these measurements have been compared to a simple sequential ionization model and are found to be in good agreement with the data. The data can be used to characterize the plasma electron density, electron temperature, and neutral atom density, since these are the only three adjustable parameters in the model and are sufficient to achieve good agreement for the time evolution of all observed charge states.