Method and apparatus for acceleration and detection of ions in an ion cyclotron resonance cell

A method and apparatus for Fourier transform mass spectrometry is disclosed in which charged particles in a magnetic field are subjected to a high voltage pulse and caused to be accelerated to larger radii of gyration. After the pulse is turned off, the charged particles move in circular orbits at frequencies given by the cyclotron equation, w=qB/m, where B is the magnetic field strength and q/m is their respective charge-to-mass ratios. The excited cyclotron motions induce the transient signal on the plates of an analyzer cell. This signal, which is a composite of all the various cyclotron frqeuencies, is digitized and stored in a computer. A mass spectrum of the ions in the analyzer cell is obtained by subjecting the signal to a Fourier transform analysis to separate the individual cyclotron frequency components. One of the advantages of this method is that the high voltage pulse accelerates all ions in the cell simultaneously.