A new system has been developed for calibration of space plasma analyzers, in particular ion mass spectrometers. The system provides a large‐area (∼250 cm2), highly parallel (±0.5°), and spatially uniform (±5%) beam of ions over the energy per charge range from 5 eV/charge to 100 keV/charge. Other special features include variable energy spread from &Dgr;E∼1 eV to ∼3 keV/charge and multiple charge state ions such as He2+or Xe9+. Among several key ion optical elements are a high‐efficiency electron bombardment ion source capable of delivering ∼10−8A, a 90° crossed electric and magnetic field mass spectrometer designed to produce either a mixed or a mass‐selected beam, and a unique beam expansion system which produces the uniform large‐area beam. The system also includes automatic beam monitoring and control via a feedback loop, as well as provisions for semiautomatic control of angle and energy analysis. Use of the calibration system during its development phases has made possible the rapid calibration of five complex satellite ion mass spectrometers already flown. Data from one of these calibrations are discussed here.