AbstractA novel ion energy analyser is developed to measure the energy distribution function f(v∩, v|) of ions lost from both ends of FRC (field-reversed configuration) plasmas. Simultaneous measurement of both parallel and perpendicular velocity components is carried out in a straight and static magnetic field. The parallel velocity component of the end-loss ions is analysed by a retarding potential parallel to the magnetic field. Selection of perpendicular energy is made by the difference in particular gyroradius in a given magnetic field. A trial to confirm the applicability has been performed on the end: loss flow from the field-reversed configuration plasma produced by the FIX (FRC injection experiment) machine.