Charged-particle energy analyzer and mass spectrometer incorporating it

An electrostatic analyzer for dispersing a beam of charged particles according to their energy, said analyzer comprising an upper and a lower group of spaced apart linear electrodes respectively disposed above and below said beam, and means for applying electrical potentials to said electrodes, each said group comprising a pair of electrodes between which one or more central electrodes are disposed, the potential of one electrode of the pair being more positive and the potential of the other electrode of the pair being more negative than the potential at which ions comprised in said beam enter the analyzer, and the potentials of all the electrodes comprising each said group progressively increasing from one electrode to the next, thereby providing in a central plane between said groups of electrodes an electrostatic field which is capable of deflecting said charged particles along different curved trajectories according to their energies.