The theory and operation of a time‐of‐flight mass spectrometer employing a multichannel electrostatic analyzer are discussed with emphasis placed on laser‐produced plasma studies. It is shown that the finite length of the analyzer leads to enhanced mass resolution. A method ofinsitucalibration of the analyzer channels is described, and measurements of the resolution and beam divergence are presented. Use of the mass spectrometer to calibrate ion‐collecting probes for mass and kinetic energy measurements is also considered.