Storage and mass-selective control of ions in an electrostatic ion storage ring

An electrostatic ion storage ring designed for atomic and molecular physics has been constructed at Tokyo Metropolitan University. A variety of molecular ions have been successfully stored, sometimes simultaneously, by taking advantage of the fact that circulation in the ring is free from mass limitations. A storage time of several minutes was attained, and several beam handling techniques were developed. The mass spectrum of the stored ions can be obtained by a Fourier transformation of the pick-up signals, mass-selective beam bunching using an RF system, and the dumping of undesired ions by pulsed electric fields. Lifetime measurements of metastable ions and laser merging experiments have demonstrated the TMU E-ring's ability to study molecular dynamics on time scales ranging from several milliseconds to several seconds.