Development of Multi-Turn Time-of-Flight Mass Spectrometers and Their Applications

The mass resolution of a time-of-flight (ToF) mass spectrometer is directly proportional to its total flight path length. We have developed multi-turn ToF mass spectrometers, where ions are stored in a fixed orbit within electrostatic sectors and allowed to propagate the said orbit numerous times. With each successive orbit, the flight path is correspondingly increasing. The first multi-turn ToF mass spectrometer, the MULTUM Linear plus, was developed for cometary exploration. The spectrometer consists of four cylindrical electrostatic sectors and 28 electrostatic quadrupole lenses. The size of the analyzer is 40 cm square. Mass resolution is demonstrated to increase according to the number of ion cycles. A mass resolution of greater than 350,000 was achieved after 501.5 cycles. Another multi-turn ToF mass spectrometer, the MULTUM II, which consists of only four toroidal electrostatic sectors, was also developed in an effort to reduce the number of quadrupole lenses. We are developing various types of mass spectrometer based on the MULTUM II technology, a ToF/ToF mass spectrometer "MULTUM- TOF/TOF", a stigmatic imaging mass spectrometer "MULTUM-IMG" and miniature mass spectrometers of high mass resolving power, the "MULTUM-S" series.