2012 Volume 60 Issue 6 Pages 87-102
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 an electrostatic sector 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 electric sectors and 28 electric 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, was also developed in an effort to reduce the number of quadrupole lenses, which consists of only four toroidal electric sectors. We are developing various types of mass spectrometers 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 ‘MULTUM-S’ series.