A novel energy/momentum spectrometer consisting of a multigrid ion energy analyzer in tandem with an inflexion focusing magnetic sector momentum analyzer is described. The entire analyzer ion flight path may be negatively biased relative to the outer (grounded) instrument housing, enabling post acceleration (up to a few keV) of grid extracted ions from laser blow‐off plasmas or laser‐initiated vacuum arcs. Used as a time‐of‐flight momentum spectrometer, the instrument is shown capable of unraveling velocity distributions and relative abundances of ions of different charge in expanding laser blow‐off plasmas, even for a few keV initial ion energy spread. Used as a discharge ion analyzer, the high mass resolution of the instrument, (m/&Dgr;m=110), enables ion isotopic species of carbon, iron and copper to be readily separated and energy analyzed. A channeltron collector provides wide dynamic range (∼105) and high time resolution (∼1.0 &mgr;s), enabling detection of low abundance species such as polymer ions in carbon discharges.