A new multi-passage time-of-flight mass spectrometer at JAIST

A new time-of-flight (TOF) mass spectrometer has been constructed at JAIST. The spectrometer consists of six electrostatic analyzers and the shape of the ion orbit resembles a racetrack oval. Produced ions are injected into the ring and fly around the circular orbit. After an appropriate number of turns, ions are ejected from the ring and directed to an ion detector. The size of the instrument is 2.5 m×3.5 m and the length of the circular orbit is 7.4 m. The mass resolution of a TOF mass spectrometer is directly proportional to the path length of the ion trajectory. Thereby, high mass resolution can easily be achieved in multiple passages in the ring. In order to avoid the spread of the ion bunch in the multiple passages, perfect isochronous focusing and spatial focusing have been introduced by a special ion optic design of the ring. In the middle of the instrument, triple isochronous focusing (displacement, angle, energy) and triple spatial focusing (two-dimensional angles, energy) are satisfied. Moreover, second- and higher-order aberrations are effectively small. The new multi-passage TOF mass spectrometer, therefore, realizes high mass resolution and high ion transmission, simultaneously.