An attachment to the EMV-100L electron microscope is described for irradiation of specimens by separated gas ions with a mass of up to 40 amu and an energy of up to 15 keV. The beam-current density at the target is about 10 mu A/cm**2. Specimens can be heated in the range of 300-1000 degree K. The attachment is designed for study of radiation damage by electron microscopy and electron diffraction.